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Purpose: To present a set of closed‐form analytical equations to create a consistent eye model balance based on clinically measured input parameters in a single step. These models complement the existing iterative approaches in the literature. Methods: Two different approaches are presented, both considering the cornea and lens as equivalent thin lenses. The first, called the Gaussian model, starts by defining the refractive error as the difference between the axial power (or dioptric distance) and the whole eye power, which can be expanded by filling in the formulas for each power. The resulting equation can be solved for either the refractive error, axial length, corneal power, lens power or the distance between the cornea and the lens as a function of the other four parameters. The second approach uses vergence calculations to provide alternative expressions, assuming that the refractive error is located at the corneal plane. Both models are explored for a biometric range typically found in adult human eyes. Results: The Gaussian and vergence models each instantly balance the input data into a working eye model over the human physiological range and far beyond as demonstrated in various examples. The equations of the Gaussian model are more complicated, while the vergence model experiences more singularities, albeit in trivial or highly unlikely parameter combinations. Conclusions: The proposed equations form a flexible and robust platform to create eye models from clinical data. Possible applications lie in creating animal eye models or providing a generic reference for real biometric data and the relationships between the ocular dimensions. [ABSTRACT FROM AUTHOR]

Abstract Background This study investigated patients’ awareness of presbyopia and its management approaches and their preferred methods for near vision correction. Methods In Saudi Arabia, 785 participants (aged between 35 and 60 years) completed a structured survey online, consisting of hard copies and direct interviews. The survey consisted of twenty-eight items divided into three parts. It was designed to record participants’ awareness of and preferences for presbyopia and its refractive corrections. Nonparametric tests and descriptive analyses were conducted to analyse participants’ responses. Result Approximately half of the participants had difficulty with near vision activities, such as reading newspapers or using mobile phones. Among all the participants, 76% were not aware of presbyopia. The prevalence of uncorrected presbyopia was 48% of the 785. The majority (82%) felt that spectacles were acceptable for correction of presbyopia. Most reported that they did not experience social stigma when using reading spectacles (87% of participants). When asked if they were aware of management approaches other than spectacles, 72% responded with not at all. Most participants had no earlier knowledge of the use of multifocal contact lenses or eye drops for presbyopia correction (67% and 82%, respectively). In the present study, some tendencies to use corrective approaches to presbyopia other than spectacles were noted. Finally, participants’ age, sex, region, education, and income had a statistically significant impact on essential parts of their responses (p

Introduction: Topographic measurement of corneal astigmatism is the current standard of care because, in addition to measuring corneal astigmatism, it identifies irregular astigmatism, which may limit optimum surgical results. The present study focuses on the use of topography to measure Surgically Induced Astigmatism (SIA), which is not a routine practice in most institutions, and compares it with keratometry values of corneal astigmatism. The present study highlights the accuracy of topography in the measurement of astigmatism, with its additional benefits being the measurement of irregular astigmatism and assessment of tear film status. Aim: To compare SIA using topography and keratometry in patients undergoing phacoemulsification and Small Incision Cataract Surgery (SICS). Materials and Methods: The present study was a prospective, interventional study conducted in the Ophthalmology Department of Bharti Vidyapeeth (deemed to be University) Medical College and Hospital, Sangli, Maharashtra, India for 18 months (November 2019 to April 2021). A total of 100 cases (100 eyes) with cataracts were randomly divided into Group-A (n=50) and Group-B (n=50), respectively, underwent Phacoemulsification and SICS. Before the surgery, the astigmatism of each patient was noted by both topography and keratometry. On the 45th postoperative day, patients’ Uncorrected Visual Acuity (UCVA), Best Corrected Visual Acuity (BCVA), automated keratometry readings, and corneal topography readings were taken, based on which SIA was calculated by SIA calculator version 2.0. The mean SIA in both groups was calculated and compared. An unpaired t-test was used to compare the mean of different variables in the two groups, Group-A and Group-B. A p-value of

Background One of the most common strabismus types in children is intermittent exotropia, which masks the deviation of one eye outward, mostly in children aged 2-4 years. It may affect visual development and often coexists with refractive mistakes. Unlike esotropia, which usually links to hyperopia, intermittent exotropia might have a different relationship with refractive errors and thus lead to myopia. Methods In this cross-sectional study from August 2021 to December 2023, 179 patients diagnosed with intermittent exotropia were recruited via an outpatient clinic of Najah Al-Quraishi, Baghdad, Iraq. The refractive errors were compared by autorefractometry and retinoscopy after cycloplegic dilation. Data analysis was constructed under the use of IBM SPSS V.26 for the determination of emmetropia, myopia, and hyperopia prevalence. Results The most expected refractive error among the 179 patients was emmetropia, which occurred in 68 patients (38%). Low hyperopia and low myopia were also common, with 64 and 40, respectively. A limited number of patients had moderate/high myopia and moderate/high hyperopia; in detail, the prevalence was following: 5% of patients had moderate myopia, while 0.5% of patients suffered from high myopia; symmetrically, 5% were moderate to high hyperopia. From the data collected, a trend emerged for a low refractive error and symmetric refractive error in both eyes. Conclusion Contrasted to prior conventional wisdom about refractive error in strabismus, it established the greater incidence of emmetropia in patients with intermittent exotropia. The findings call for specific management strategies to be applied in this population.

Background: This study investigated patients' awareness of presbyopia and its management approaches and their preferred methods for near vision correction. Methods: In Saudi Arabia, 785 participants (aged between 35 and 60 years) completed a structured survey online, consisting of hard copies and direct interviews. The survey consisted of twenty-eight items divided into three parts. It was designed to record participants' awareness of and preferences for presbyopia and its refractive corrections. Nonparametric tests and descriptive analyses were conducted to analyse participants' responses. Result: Approximately half of the participants had difficulty with near vision activities, such as reading newspapers or using mobile phones. Among all the participants, 76% were not aware of presbyopia. The prevalence of uncorrected presbyopia was 48% of the 785. The majority (82%) felt that spectacles were acceptable for correction of presbyopia. Most reported that they did not experience social stigma when using reading spectacles (87% of participants). When asked if they were aware of management approaches other than spectacles, 72% responded with not at all. Most participants had no earlier knowledge of the use of multifocal contact lenses or eye drops for presbyopia correction (67% and 82%, respectively). In the present study, some tendencies to use corrective approaches to presbyopia other than spectacles were noted. Finally, participants' age, sex, region, education, and income had a statistically significant impact on essential parts of their responses (p < 0.05). Conclusion: Presbyopia is a highly prevalent age-related ocular disorder, and a significant percentage of cases are uncorrected due to a lack of awareness or reluctance to wear spectacles. More efficient health education about presbyopia and its corrective alternatives is urgently needed. [ABSTRACT FROM AUTHOR]

Introduction: Topographic measurement of corneal astigmatism is the current standard of care because, in addition to measuring corneal astigmatism, it identifies irregular astigmatism, which may limit optimum surgical results. The present study focuses on the use of topography to measure Surgically Induced Astigmatism (SIA), which is not a routine practice in most institutions, and compares it with keratometry values of corneal astigmatism. The present study highlights the accuracy of topography in the measurement of astigmatism, with its additional benefits being the measurement of irregular astigmatism and assessment of tear film status. Aim: To compare SIA using topography and keratometry in patients undergoing phacoemulsification and Small Incision Cataract Surgery (SICS). Materials and Methods: The present study was a prospective, interventional study conducted in the Ophthalmology Department of Bharti Vidyapeeth (Deemed to be University) Medical College and Hospital, Sangli, Maharashtra, India for 18 months (November 2019 to April 2021). A total of 100 cases (100 eyes) with cataracts were randomly divided into Group-A (n=50) and Group-B (n=50), respectively, underwent Phacoemulsification and SICS. Before the surgery, the astigmatism of each patient was noted by both topography and keratometry. On the 45th postoperative day, patients’ Uncorrected Visual Acuity (UCVA), Best Corrected Visual Acuity (BCVA), automated keratometry readings, and corneal topography readings were taken, based on which SIA was calculated by SIA calculator version 2.0. The mean SIA in both groups was calculated and compared. An unpaired t-test was used to compare the mean of different variables in the two groups, Group-A and Group-B. A p-value of <0.05 was considered statistically significant. Results: The majority of cases were in the age group of 61- 70 years, with 23 (46%) cases in Group-A and 27 (54%) in Group-B. In the study, the mean SIA by keratometry in Group-A was 0.43±0.02D and in Group-B was 1.24±0.04D (p<0.0001), and the mean SIA by topography in Group-A was 0.49±0.02D and in Group-B was 1.28±0.03D (p<0.0001), indicating that phacoemulsification causes less SIA compared to SICS. Upon comparing the mean SIA calculated by keratometry and topography in both study groups, it was found that p<0.02 in Group-A and p<0.4 in Group-B, suggesting that both p-values are not significant. This indicates that both keratometry and topography will give similar results and can be used for determining SIA. Conclusion: The study showed that phacoemulsification produces less mean SIA compared to SICS, leading to better visual outcomes and early visual rehabilitation in contrast to the SICS group. The present study also concluded that both keratometry and corneal topography can be used for the calculation of SIA as both give similar results, although topography remains an important tool in the calculation of Intraocular Lens (IOL) power in patients with corneal pathologies and post-refractive surgeries. [ABSTRACT FROM AUTHOR]

Purpose: To compare axial length (AL) growth curves in East Asian (EA) and non‐EA emmetropes. Methods: A meta‐regression of 28 studies with emmetrope‐specific AL data (measured with optical biometry) was performed. Emmetropia was defined as spherical equivalent refraction (SER) between −0.50 and +1.25 D, determined under cycloplegia if the mean age was ≤20 years. The AL growth curve (mean AL vs. mean age) was first fitted to the full dataset using a weighted nonlinear mixed‐effects model, before refitting the model with ethnicity as a two‐level grouping variable (EA vs. non‐EA). Ethnic differences in growth curve parameters were tested using the Wald test. Results: A total of 3331 EA and 1071 non‐EA emmetropes (mean age: 6.5–23.1 years) were included. There was no evidence of an ethnic difference in either final AL (difference: 0.15 mm, 95% CI: −0.04 to 0.35 mm, p = 0.15) or initial AL, as represented by the amount that the final AL needed to be offset to obtain the y‐intercept (difference: −2.77 mm, 95% CI: −10.97 to 5.44, p = 0.51). Likewise, AL growth rate (curve steepness) did not differ between ethnic groups (difference: 0.09, 95% CI: −0.13 to 0.31, p = 0.43). Collectively, AL growth rate decreased from 0.24 mm/year at 6 years of age to around 0.05 mm/year at 11 years of age, after which it dipped below the repeatability of optical biometry (±0.04 mm) and practically plateaued around 16 years of age (final AL: 23.60 mm). Conclusions: EA and non‐EA emmetropes have comparable AL growth curves. [ABSTRACT FROM AUTHOR]

Purpose: To report variation of the axial length (AL) and anterior chamber depth (ACD) among keratoconic (KC) eyes compared to myopic and emmetropic eyes in an African population sample. Study Design: Cross sectional observational. Place and Duration of Study: Al-Faisal Eye Hospital at Khartoum state of Sudan from January 2022 to September 2022. Methods: One-hundred and twenty-four eyes of 62 patients were divided into KC group (n =17, eyes = 34), myopic group (n = 28, eyes = 56), and an age/gender matched emmetropic group (n = 17, eyes = 34). Central corneal thickness (CCT) was measured using ultrasonic pachymeter, AL, ACD and keratometry readings (K-reading) were recorded for each patient using non-contact partial coherence interferometry with an IOL Master. Results: Mean age of the sample population was 22.27 ± 6.05 (range; 10 - 40 years). KC patients had the highest spherical equivalent of refraction (SER) (-6.19±3.91 dioptres), highest k-reading (48.98±5.68 dioptres) and the thinnest CCT. Myopic participants had a longer AL compared to other refractive error groups (AL = 24.99 ± 2.39, p < 0.001). KC patients exhibited a larger ACD in comparison to emmetropes and myopes (ACD=3.69 ± 0.26, p < 0.001). Among all participants, SER exhibited the highest correlation with AL (r = -0.71, p < 0.001) followed by a weaker correlation with ACD (r= -0.26, p = 0.003). However, among KC patients, SER exhibited a weaker correlation with AL compared to myopes (r = -0.55, p = 0.001), and a higher correlation with ACD compared to myopes (r= -0.38, p = 0.03). Conclusion: ACD and corneal curvature were the most significantly detrimental parameters in KC. KC participants demonstrated a lower correlation between SER and AL and higher correlation between SER and ACD. [ABSTRACT FROM AUTHOR]

Background. Determining the biomechanical properties of the cornea is an urgent applied scientific task of modern clinical ophthalmology, since the cornea is a marker of changes in the biomechanical behavior of the eye. A number of studies show that corneal biomechanics changes in patients with myopia and depends on its degree. The aim of our study was to determine the influence of corneal rigidity on intraocular pressure (IOP) indicators with different types of tonometry in patients with emmetropia and myopia of varying degrees. Materials and methods. One hundred and ninety- four patients (372 eyes) with emmetropia (60 eyes) and myopia (312 eyes) of varying degrees participated in the study. Their average age was 25 ± 2 years. Among the examined, there were 95 men (48.97 %) and 99 women (51.03 %). Determination of biomechanical properties, the coefficient of corneal rigidity (KER) was carried out using the formula and method for assessing the corneal rigidity (Sergienko M.M., Shargorodska I.V., 2008). For each eye, we calculated the intraocular pressure with the coefficient of corneal rigidity — IOP(k) and the correction factor taking into account the coefficient of corneal rigidity — k. Results. The analysis of the results demonstrated the influence of the central corneal thickness (CCT) on tonometry indicators when determining IOP in emmetropic eyes by the Maklakov method (r = 0.532, p < 0.05), ricochet tonometry (r = 0.334, p < 0.05) and especially pneumotonometry (r = 0.611, p < 0.05). The effect of CCT on tonometry was smallest in Goldman applanation tonometry (r = 0.186, p < 0.05). The results show the absence of a correlation between the coefficient of corneal rigidity in emmetropic eyes and the central corneal thickness, the independence of this indicator from the level of intraocular pressure, which was confirmed by the determination of IOP by various methods, and the effect of CCT on KER. It was found that the coefficient of corneal rigidity of myopic eyes depended on the CCT and correlated with the degree of myopia. At the same time, there was a lack of correlation between KER of myopic eyes and the central corneal thickness. The values of IOP obtained using ricochet tonometry on eyes with mild and moderate myopia almost did not differ from that of Goldmann applanation tonometry and were significantly lower with severe myopia (t = –2.63, p = 0.005). Conclusions. As a result of the conducted research, it was found that determining the biomechanical properties of the cornea is of great importance for accurate measurement of intraocular pressure. A more effective technique is the intravital calculation of the coefficient of corneal rigidity and its consideration as an adjustment when determining the estimated IOP in emmetropic eyes and eyes with varying degrees of myopia. [ABSTRACT FROM AUTHOR]

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Background and Objectives: Hyperopia is a refractive error which affects cognitive and social development if uncorrected and raises the risk of primary angle-closure glaucoma (PACG). Materials and Methods: The study included only the right eye—40 hyperopic eyes in the study group (spherical equivalent (SE) under pharmacological cycloplegia over 0.50 D), 34 emmetropic eyes in the control group (SE between −0.50 D and +0.50 D). A complete ophthalmological evaluation was performed, including autorefractometry to measure SE, and additionally we performed Ocular Response Analyser: Corneal Hysteresis (CH), Corneal Resistance Factor (CRF); specular microscopy: Endothelial cell density (CD), Cell variability (CV), Hexagonality (Hex), Aladdin biometry: Anterior Chamber Depth (ACD), Axial Length (AL), Central Corneal Thickness (CCT). IBM SPSS 26 was used for statistical analysis. Results: The mean age of the entire cohort was 22.93 years (SD ± 12.069), 66.22% being female and 33.78% male. The hyperopic eyes had significantly lower AL, ACD, higher SE, CH, CRF. In the hyperopia group, there are significant, negative correlations between CH and AL (r −0.335), CRF and AL (r −0.334), SE–AL (r −0.593), ACD and CV (r −0.528), CV and CRF (r −0.438), CH (r −0.379), and positive correlations between CCT and CH (r 0.393) or CRF (r 0.435), CD and ACD (r 0.509) or CH (0.384). Age is significantly, negatively correlated with ACD (r −0.447), CH (r −0.544), CRF (r −0.539), CD (r −0.546) and positively with CV (r 0.470). Conclusions: Our study suggests a particular biomechanical behavior of the cornea in hyperopia, in relation with morphological and endothelial parameters. Moreover, the negative correlation between age and ACD suggests a shallower anterior chamber as patients age, increasing the risk for PACG. [ABSTRACT FROM AUTHOR]

Purpose. To investigate the influence of the axial length of eyes on the average macular thickness and to develop a method for assessing this optical coherence tomography (OCT) parameter in patients with refractive errors. Material and methods. The study involved 132 patients (132 eyes) over 40; of these, 43 patients with hyperopia (axial length 20–22 mm), 38 patients with myopia (axial length 25–28 mm) and 51 healthy subjects with emmetropia with similar gender and age distribution (axial length 22.5–24.5 mm). OCT was performed on a Cirrus HD-OCT device (Carl Zeiss Meditec, USA). Results. The average macular thickness in the emmetropia group was 282.4 ± 10.2 (261–304) μm. In patients with myopia, it was on average 7 μm less (274.9 ± 10.5; from 250 to 296 μm, p = 0.005), and in patients with hyperopia it was almost 6 μm thicker (288.2 ± 12.5; from 258 to 313 μm, p = 0.032). In the emmetropia group, normative data for the average macular thickness were determined. For eyes with the axial length of 20–22 and 25–28 mm, corrections for calculating the average macular thickness in emmetropic eyes have been developed, allowing comparison with the normative data. Conclusion. The average macular thickness decreases with the increase of the axial length of the eye. An original technique for assessing the average macular thickness in patients with refractive errors, adapted to the Cirrus HD-OCT device, was developed. For this device, the normative database of healthy subjects with emmetropia aged of 41–80 years has been compiled.

Abstract Background We aimed to investigate children with an emmetropic non-cycloplegic refraction (NCR) to compare the difference in progression of NC spherical equivalent (SE) over 2 years between the children with emmetropic and hyperopic cycloplegic refraction (CR) values. Methods Through a retrospective medical record review, 59 children aged under 10 years were evaluated. Refractive error was calculated as the average of the SE values of both eyes. According to the CR results, children with emmetropia (-0.50 to 1.00 diopter [D]) were assigned to group 1 (n = 29), and those with hyperopia (≥ 1.00 D) were assigned to group 2 (n = 30). The prevalence of myopia and SE progression were compared over 2 years. Correlations between final SE progression and baseline age and refractive error were analyzed and multiple regression analysis was conducted. Receiver operating characteristic curves that achieved the best cutoff points to distinguish between the groups were calculated. Results Group 1 showed significantly myopic SE changes compared to baseline at the 1-year follow-up, and group 1 was significantly myopic compared with group 2 at the 2-year follow-up. Myopia prevalence was 51.7% in group 1 and 6.7% in group 2 after 1 year, and 61.1% and 16.7% after 2 years, respectively. In the correlation analysis, baseline age, baseline CR, and difference between CR and NCR showed significant correlations with the 2-year SE progression (r = -0.359, p = 0.005; r = 0.450, p

Purpose: To evaluate the normal refractive state in horses in NCSU and ECMR and determine the prevalence of naturally occurring refractive errors and their association with breed, age, coat color, iris color, sex, and geographic location. Methods: Horses from NCSU (January 2009–November 2012) and ECMR (January 2013–September 2016) underwent ophthalmic examination and streak retinoscopy. Location, color, breed, sex, and iris color were recorded. Gross and net refractive values for each meridian (horizontal and vertical), spherical refraction, astigmatism for both eyes, and anisometry were recorded, and statistical analyses were performed. Results: There is excellent agreement in refraction between the eyes of the same horse (ICC = 0.89). The median net horizontal (H), vertical (V), and spherical refraction for the total population (n = 690) were H: +0.25 D (min. −6.50 D, max. +2.34 D), V: +0.25 D (min. −7.13 D, max. +2.75D), and spherical: +0.25 D (min. −6.82 D, max. +2.17 D), all with interquartile ranges of −0.25 to 0.25 D. Emmetropia (>−0.50 D and <+0.50 D; >−0.75 D and <+0.75 D) was present in 769/1380 eyes (55.7%) and 926/1380 eyes (67.1%), respectively. Anisometropia was present in 86/690 horses (12.5%). Sex, iris color, and location were significantly associated with refraction values, whereas age, breed, and coat color were not. Conclusions: Most eyes evaluated are emmetropic, or shifted myopically, with excellent agreement between eyes of the same horse. Sex, iris color, and geographic location appear to impact refraction in horses. Support: None. [ABSTRACT FROM AUTHOR]

The purpose of the study was to evaluate the occurrence and range of refractive errors in dogs of different ages. A total of 99 clinically healthy, mixed-breed mesocephalic dogs were included in the study and divided into three different age groups according to the current human/pet analogy chart: 40 adults (23 males, 17 females, 1-8 years old, 3-70 kg), 21 seniors (14 males, 7 females, 6-11 years old, 7-42 kg), and 38 geriatrics (22 males, 16 females, 8-13 years old, 5-45 kg). All the dogs underwent an ophthalmic examination, including Schirmer tear test, tonometry, biomicroscopy, and ophthalmoscopy. Neither eye drops nor pharmacological sedatives were administered before the autorefractometry. The refractive states were assessed bilaterally using a hand-held Retinomax 3 (Righton) autorefractor. The results underwent statistical analysis using Statistica v12 software (ANOVA and t-test). A P-value -0.5 D and < +0.5 D, was found in 36% of the adult, 43% of the senior, and 38% of the geriatric patients. Anisometropia was found in 1% of the adult, 9.5% of the senior and 5.5% of the geriatric dogs when the refractive power of the two eyes differed ≥ 1.0 myopia ≤ -0.5 D and hyperopia ≥ +0.5 D were found in 23% and 41% of the adult eye globes as well as 24% and 33% in the senior dogs and 15% and 47% in the geriatric dogs, respectively. The maximal values of the myopia in the adult and geriatric dogs were -2.5 D and -2.75 D, respectively. The maximal values of the hyperopia in the adult and geriatric dogs were 1.75 D and 2.5 D, respectively. No statistically significant correlation was found between the groups. Ametropia is a common refractive state for dogs of different ages. The most frequent refractive state in ametropic mixed-bed dogs in all age groups is hyperopia.

Purpose: To investigate the diurnal variation in subfoveal choroidal thickness (SFCT) during the waking period over three consecutive days in different degrees of myopia and emmetropia. Methods: A total of 60 adult volunteers were grouped into low, moderate, high myopia, and emmetropia subgroups. SFCT, axial length (AL), anterior chamber depth (ACD), and intraocular pressure (IOP) were measured every 2 h from 8 AM to 8 PM for three successive days. Results: The mean values of daily change amplitude were 3.18 mmHg (IOP), 0.05 mm (AL), 0.17 mm (ACD), and 13.51 mm (SFCT). The values of AL and ACD increased simultaneously with spherical equivalent refraction (SER), but SFCT was the opposite. IOP had a diurnal variation, and there was no difference among the four groups. AL of the high myopia group, ACD of the emmetropia group, and SFCT of each myopia group had diurnal variation over three consecutive days. AL had a high mean value at noon every day, and SFCT had a low mean value at noon every day. Conclusion: The choroid thickness of subjects with different degrees of myopia had a significant diurnal variation. The change of diurnal variation between emmetropic and myopic subjects may be one of the causes of myopia. [ABSTRACT FROM AUTHOR]

OBJECTIVE: The purpose of this study was to investigate the relationship between corneal biomechanics and ocular morphology in myopic children and adolescents. PATIENTS AND METHODS: The study included 170 right eyes, from 170 patients under the age of 18 years, who underwent a complete ophthalmologic examination, gathering the following data: spherical equivalent (SE) (under pharmacological cycloplegia), biomechanical parameters - corneal hysteresis (CH) and corneal resistance factor (CRF), structural parameters - axial length (AL) and central corneal thickness (CCT). RESULTS: The average age of the patients was 15.26 years old (55.29% girls, 44.70% boys). Out of the 170 eyes, 111 were myopic eyes and 59 were emmetropic. Myopic eyes had a significantly lower CH (p=0.001), CRF (p=0.002) and CCT (p=0.009), and higher AL (p<0.001) than emmetropic eyes. The AL and CCT were significantly higher in myopic males, compared to myopic females (p<0.001 and 0.001). In myopes, we found statistically significant negative correlations between AL and CH (Pearson's r=-0.218), CRF (r=-0.226) and also SE (r=-0.539), and positive between SE and either CH (r=0.193) or CRF (r=0.201). CONCLUSIONS: Corneal biomechanical properties are significantly related to myopia parameters in children. [ABSTRACT FROM AUTHOR]

Background: We aimed to investigate children with an emmetropic non-cycloplegic refraction (NCR) to compare the difference in progression of NC spherical equivalent (SE) over 2 years between the children with emmetropic and hyperopic cycloplegic refraction (CR) values. Methods: Through a retrospective medical record review, 59 children aged under 10 years were evaluated. Refractive error was calculated as the average of the SE values of both eyes. According to the CR results, children with emmetropia (-0.50 to 1.00 diopter [D]) were assigned to group 1 (n = 29), and those with hyperopia (≥ 1.00 D) were assigned to group 2 (n = 30). The prevalence of myopia and SE progression were compared over 2 years. Correlations between final SE progression and baseline age and refractive error were analyzed and multiple regression analysis was conducted. Receiver operating characteristic curves that achieved the best cutoff points to distinguish between the groups were calculated. Results: Group 1 showed significantly myopic SE changes compared to baseline at the 1-year follow-up, and group 1 was significantly myopic compared with group 2 at the 2-year follow-up. Myopia prevalence was 51.7% in group 1 and 6.7% in group 2 after 1 year, and 61.1% and 16.7% after 2 years, respectively. In the correlation analysis, baseline age, baseline CR, and difference between CR and NCR showed significant correlations with the 2-year SE progression (r = -0.359, p = 0.005; r = 0.450, p < 0.001; r = -0.562, p < 0.001, respectively). However, NCR refractive error showed no significant correlation (r = -0.097, p = 0.468). In multiple regression analysis, baseline age (β= -0.082), and CR-NCR difference (β= -0.214) showed a significant effect on SE progression for 2 years. When an NCR value of 0.20 D was set as the cut-off value to distinguish between the groups, a sensitivity of 70% and specificity of 92% were obtained. Conclusion: Even if NCR showed emmetropia, children with baseline CR values of emmetropia showed greater SE progression compared with those with hyperopia. Cycloplegia is essential to confirm the correct refractive status in children. It may be useful for predicting prognosis of SE progression. [ABSTRACT FROM AUTHOR]

In the context of ocular development and eye growth regulation, retinal defocus and/or image contrast appear key variables although the nature of the signal(s) relayed from the retina to the sclera remains poorly understood. Nonetheless, under optimal visual conditions, eye length is brought into alignment with its optical power to achieve approximate emmetropia, through appropriate adjustment to eye growth. The retinal pigment epithelium (RPE), which lies between the retina and choroid/sclera, appears to play a crucial role in this process. In the investigations reported here, we used a chick model system to assess the threshold duration of exposure to lens-imposed defocus and form-deprivation necessary for conversion of evoked retinal signals into changes in BMP gene expression in the RPE. Our study provides evidence for the following: 1) close-loop, optical defocus-guided (negative and positive lenses) bidirectional BMP gene expression regulation, 2) open-loop, form-deprivation (diffusers)-induced down-regulation of BMP gene expression, and 3) early, transient up-regulation of BMP gene expression in response to both types of lens and diffuser applications. The critical exposure for accurately encoding retinal images as biological signals at the level of the RPE is in the order of minutes to hours, depending on the nature of the visual manipulations.

In the context of ocular development and eye growth regulation, retinal defocus and/or image contrast appear key variables although the nature of the signal(s) relayed from the retina to the sclera remains poorly understood. Nonetheless, under optimal visual conditions, eye length is brought into alignment with its optical power to achieve approximate emmetropia, through appropriate adjustment to eye growth. The retinal pigment epithelium (RPE), which lies between the retina and choroid/sclera, appears to play a crucial role in this process. In the investigations reported here, we used a chick model system to assess the threshold duration of exposure to lens-imposed defocus and form-deprivation necessary for conversion of evoked retinal signals into changes in BMP gene expression in the RPE. Our study provides evidence for the following: 1) close-loop, optical defocus-guided (negative and positive lenses) bidirectional BMP gene expression regulation, 2) open-loop, form-deprivation (diffusers)-induced down-regulation of BMP gene expression, and 3) early, transient up-regulation of BMP gene expression in response to both types of lens and diffuser applications. The critical exposure for accurately encoding retinal images as biological signals at the level of the RPE is in the order of minutes to hours, depending on the nature of the visual manipulations.

Purpose:To investigate differences in sensitivity to myopia-inducing stimuli of two strains of pigmented guinea pigs. Methods:Eleven-day-old animals (New Zealand [NZ], n = 24 and Elm Hill strains [EH], n = 26) wore either a +2 or -2 diopter (D) lens over one eye and a plano lens over the fellow eye for 5 days; other 10-day-old EH (n = 9) and 7-day-old NZ (n = 9) animals were monocularly form-deprived (FD) for 28 days. Choroidal thickness and axial length were measured using A-scan ultrasonography at baseline and after 1 and 5 days for optical defocus treatments, and at baseline and after 28 days for the FD treatment. Refractive errors were measured by retinoscopy. Choroids of untreated animals were also evaluated using spectral-domain optical coherence tomography. Results:One day of optical defocus induced bidirectional (optical sign-dependent) choroidal responses in EH animals only (P < 0.01). Similar responses were detected in NZ animals after 5 days (P < 0.01), with concordant spherical equivalent refraction changes (P < 0.01). Compared with NZ animals, EH animals developed minimal myopia with FD after 28 days (-4.58 ± 0.97 vs. -0.69 ± 0.75 D for NZ versus EH, P < 0.001). Yet, EH animals showed paradoxical choroidal thickening, 20 ± 9 vs. -8 ± 8 μm for EH versus NZ, P < 0.001. Untreated EH animals also had significantly thicker choroids than NZ animals (147 ± 19 vs. 132 ± 16 μm, P < 0.05), with well-defined layering. Conclusions:As previously reported in chicks, guinea pigs show strain-related differences in response to myopia-inducing stimuli. The finding of a thicker, multilayered choroid in the strain showing decreased sensitivity to FD is provocative, suggesting a possible protective role of the choroid.

AIM: To examine the prevalence and composition of refractive errors in Hungary. METHODS: Nationwide cross-sectional data collected between 2014 and 2019 were analysed from the Comprehensive Health Screening Program of Hungary, which provided spectacle dioptric power and autorefractometry data for 68 227 people (35 850 women and 32 377 men). Their age distribution, 18-99y, was similar to the national demographic distributions. RESULTS: Of the total population, 16.50% of the refractive errors exhibited hyperopia, 40.05% emmetropia, and 43.45% myopia. Myopia was 3 times more frequent (58.7%) in younger ages (18-35y of age) compared to older age groups (19.4% of those 56-70y of age; P

Background: Body mass index (BMI) uses a person's weight and height to estimate body fat as an indication of an individual's health status. Several studies have suggested that BMI (calculated as weight in kilograms divided by the square of height in metres) was related to central corneal thickness (CCT) in non-emmetropic subjects; however, there is limited information about the possible correlation between BMI and the CCT in healthy emmetropic eyes. Aim: This study aimed to investigate the correlation between CCT and BMI in healthy emmetropic eyes. Setting: The study was performed by the GIAVAL research group of the Faculty of Medicine and Odontology, University of Valencia, Spain. Methods: The emmetropic eyes of 81 (mean age ± standard deviation [s.d.]: 21.8 ± 1.8 years) adults were included in this retrospective study. Ophthalmic CCT measurements were measured using non-invasive scanning-slit corneal topography. The height and weight of all subjects, using a standard tape measure and weight scale, were recorded, and BMI was calculated. Results: There were no significant correlations between CCT and the BMI values in the 81 emmetropic adults (r = 0.16; p = 0.135), between CCT values and BMI (18.5 to < 25) (r = 0.21; p = 0.724) and between CCT values and BMI (25.0 to < 30) (r = -0.28; p = 0.465). In addition, no correlation occurs between the CCT values and BMI in both women (r = 0.22; p = 0.160) and men (r = -0.14; p = 0.412). A weak negative correlation does seem to present with age and CCT (r = -0.29; p < 0.05). However, the coefficient of determination suggests that only 8% (r² = 0.08) of the variance is shared between age and CCT. Conclusion: The results do not show a correlation between CCT and BMI values in young subjects with healthy emmetropic eyes. Contribution: This study has revealed that the CCT values are not correlated with the BMI values in healthy emmetropic eyes of young subjects without obesity. In addition, normative data for the CCT in normal anatomic eyes has been reported, which will serve as a baseline for future comparative studies in non-emmetropic eyes. [ABSTRACT FROM AUTHOR]

The purpose of the study was to evaluate the occurrence and range of refractive errors in dogs of different ages. A total of 99 clinically healthy, mixed-breed mesocephalic dogs were included in the study and divided into three different age groups according to the current human/pet analogy chart: 40 adults (23 males, 17 females, 1–8 years old, 3–70 kg), 21 seniors (14 males, 7 females, 6–11 years old, 7–42 kg), and 38 geriatrics (22 males, 16 females, 8–13 years old, 5–45 kg). All the dogs underwent an ophthalmic examination, including Schirmer tear test, tonometry, biomicroscopy, and ophthalmoscopy. Neither eye drops nor pharmacological sedatives were administered before the autorefractometry. The refractive states were assessed bilaterally using a hand-held Retinomax 3 (Righton) autorefractor. The results underwent statistical analysis using Statistica v12 software (ANOVA and t-test). A P-value < 0.05 was considered as significant. Emmetropia, defined as a refractive state > −0.5 D and < +0.5 D, was found in 36% of the adult, 43% of the senior, and 38% of the geriatric patients. Anisometropia was found in 1% of the adult, 9.5% of the senior and 5.5% of the geriatric dogs when the refractive power of the two eyes differed ≥ 1.0 myopia ≤ −0.5 D and hyperopia ≥ +0.5 D were found in 23% and 41% of the adult eye globes as well as 24% and 33% in the senior dogs and 15% and 47% in the geriatric dogs, respectively. The maximal values of the myopia in the adult and geriatric dogs were −2.5 D and −2.75 D, respectively. The maximal values of the hyperopia in the adult and geriatric dogs were 1.75 D and 2.5 D, respectively. No statistically significant correlation was found between the groups. Ametropia is a common refractive state for dogs of different ages. The most frequent refractive state in ametropic mixed-bed dogs in all age groups is hyperopia. [ABSTRACT FROM AUTHOR]

Purpose: To compare the stereoacuity in patients with anisometropia, isometropia, and emmetropia.Methods: A cross-sectional study was conducted on 1403 subjects (range: 5-45 years) divided into anisometropes (n = 403), isometropes (n = 500), and emmetropes (n = 500). There were 258 amblyopic eyes among anisometropes and 156 amblyopic eyes among isometropes. Stereoacuity was measured using the Titmus stereo test consisting of a combination of contour targets.Results: There were 675 males and 728 females. A significant (P < 0.001) reduction in stereoacuity was found in anisometropes as compared to isometropes and emmetropes. The stereoacuity was even worse in amblyopes as compared to non-amblyopes. Most patients with anisometropia of <3.0 D had fair stereoacuity. However, as the degree of anisometropia increased to >3.0 D, stereoacuity deteriorated gradually. Marked reduction of stereoacuity was observed in severe degree of anisometropia (>6.0 D). Overall, an anisometropia of ≥2.12 D was associated with reduced stereoacuity. Among the anisometropes, it was found to be the poorest in myopia, followed by myopia with astigmatism, hypermetropia with astigmatism, and hypermetropia.Conclusion: The level of stereoacuity was worse in anisometropes as compared to isometropes and emmetropes. Amblyopes had a greater reduction in stereoacuity than non-amblyopes. Stereoacuity decreased as the degree of anisometropia increased. Among the anisometropes, myopes had worst stereoacuity than hypermetropes. [ABSTRACT FROM AUTHOR]

Background and Objectives: Hyperopia is a refractive error which affects cognitive and social development if uncorrected and raises the risk of primary angle-closure glaucoma (PACG). Materials and Methods: The study included only the right eye—40 hyperopic eyes in the study group (spherical equivalent (SE) under pharmacological cycloplegia over 0.50 D), 34 emmetropic eyes in the control group (SE between −0.50 D and +0.50 D). A complete ophthalmological evaluation was performed, including autorefractometry to measure SE, and additionally we performed Ocular Response Analyser: Corneal Hysteresis (CH), Corneal Resistance Factor (CRF); specular microscopy: Endothelial cell density (CD), Cell variability (CV), Hexagonality (Hex), Aladdin biometry: Anterior Chamber Depth (ACD), Axial Length (AL), Central Corneal Thickness (CCT). IBM SPSS 26 was used for statistical analysis. Results: The mean age of the entire cohort was 22.93 years (SD ± 12.069), 66.22% being female and 33.78% male. The hyperopic eyes had significantly lower AL, ACD, higher SE, CH, CRF. In the hyperopia group, there are significant, negative correlations between CH and AL (r −0.335), CRF and AL (r −0.334), SE–AL (r −0.593), ACD and CV (r −0.528), CV and CRF (r −0.438), CH (r −0.379), and positive correlations between CCT and CH (r 0.393) or CRF (r 0.435), CD and ACD (r 0.509) or CH (0.384). Age is significantly, negatively correlated with ACD (r −0.447), CH (r −0.544), CRF (r −0.539), CD (r −0.546) and positively with CV (r 0.470). Conclusions: Our study suggests a particular biomechanical behavior of the cornea in hyperopia, in relation with morphological and endothelial parameters. Moreover, the negative correlation between age and ACD suggests a shallower anterior chamber as patients age, increasing the risk for PACG.

Purpose: To compare the stereoacuity in patients with anisometropia, isometropia, and emmetropia. Methods: A cross-sectional study was conducted on 1403 subjects (range: 5–45 years) divided into anisometropes (n = 403), isometropes (n = 500), and emmetropes (n = 500). There were 258 amblyopic eyes among anisometropes and 156 amblyopic eyes among isometropes. Stereoacuity was measured using the Titmus stereo test consisting of a combination of contour targets. Results: There were 675 males and 728 females. A significant (P < 0.001) reduction in stereoacuity was found in anisometropes as compared to isometropes and emmetropes. The stereoacuity was even worse in amblyopes as compared to non-amblyopes. Most patients with anisometropia of 3.0 D, stereoacuity deteriorated gradually. Marked reduction of stereoacuity was observed in severe degree of anisometropia (>6.0 D). Overall, an anisometropia of ≥2.12 D was associated with reduced stereoacuity. Among the anisometropes, it was found to be the poorest in myopia, followed by myopia with astigmatism, hypermetropia with astigmatism, and hypermetropia. Conclusion: The level of stereoacuity was worse in anisometropes as compared to isometropes and emmetropes. Amblyopes had a greater reduction in stereoacuity than non-amblyopes. Stereoacuity decreased as the degree of anisometropia increased. Among the anisometropes, myopes had worst stereoacuity than hypermetropes.

Purpose: To determine whether accommodative errors in emmetropes and myopes are systematically different, and the effect of using different instruments and metrics. Methods: Seventy‐six adults aged 18–27 years comprising 24 emmetropes (spherical equivalent refraction of the dominant eye +0.04 ± 0.03 D) and 52 myopes (−2.73 ± 0.22 D) were included. Accommodation responses were measured with a Grand Seiko WAM‐5500 and a Hartmann–Shack Complete Ophthalmic Analysis System aberrometer, using pupil plane (Zernike and Seidel refraction) and retinal image plane (neural sharpness—NS; and visual Strehl ratio for modulation transfer function—VSMTF) metrics at 40, 33 and 25 cm. Accommodation stimuli were presented to the corrected dominant eye, and responses, referenced to the corneal plane, were determined in the fellow eye. Linear mixed‐effects models were used to determine influence of the refractive group, the measurement method, accommodation stimulus, age, race, parental myopia, gender and binocular measures of heterophoria, accommodative convergence/accommodation and convergence accommodation/convergence ratios. Results: Lags of accommodation were affected significantly by the measurement method (p < 0.001), the refractive group (p = 0.003), near heterophoria (p = 0.002) and accommodative stimulus (p < 0.05), with significant interactions between some of these variables. Overall, emmetropes had smaller lags of accommodation than myopes with respective means ± standard errors of 0.31 ± 0.08 D and 0.61 ± 0.06 D (p = 0.003). Lags were largest for the Grand Seiko and Zernike defocus, intermediate for NS and VSMTF, and least for Seidel defocus. Conclusions: The mean lag of accommodation in emmetropes is approximately equal to the previously reported depth of focus. Myopes had larger (double) lags than emmetropes. Differences between methods and instruments could be as great as 0.50 D, and this must be considered when comparing studies and outcomes. Accommodative lag increased with the accommodation stimulus, but only for methods using a fixed small pupil diameter. [ABSTRACT FROM AUTHOR]

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The vitreous humor (VH) is a transparent gelatin-like substance that occupies two-thirds of the eyeball and undergoes the most significant changes during eye elongation. Quantitative proteomics on the normal growth period in the VH could provide new insights into understanding its progression mechanism in the early stages of myopia. In this study, a data-independent acquisition (SWATH-MS) was combined with targeted LC-ESI-MS/MS to identify and quantify the relative protein changes in the vitreous during the normal growth period (4, 7, 14, 21 and 28 days old) in the chick model. Chicks were raised under normal growing conditions (12/12 h Dark/light cycle) for 28 days, where ocular measurements, including refractive and biometric measurements, were performed on days 4 (baseline), 7, 14, 21 and 28 ( n = 6 chicks at each time point). Extracted vitreous proteins from individual animals were digested and pooled into a left eye pool and a right pool at each time point for protein analysis. The vitreous proteome for chicks was generated using an information-dependent acquisition (IDA) method by combining injections from individual time points. Using individual pool samples, SWATH-MS was employed to quantify proteins between each time point. DEPs were subsequently confirmed in separate batches of animals individually on random eyes ( n = 4) using MRMHR between day 7 and day 14. Refraction and vitreous chamber depth (VCD) were found to be significantly changed ( p < 0.05, n = 6 at each time point) during the period. A comprehensive vitreous protein ion library was built with 1576 non-redundant proteins (22987 distinct peptides) identified at a 1% false discovery rate (FDR). A total of 12 up-regulated and 26 down-regulated proteins were found across all time points compared to day 7 using SWATH-MS. Several DEPs, such as alpha-fetoprotein, the cadherin family group, neurocan, and reelin, involved in structural and growth-related pathways, were validated for the first time using MRMHR under this experimental condition. This study provided the first comprehensive spectral library of the vitreous for chicks during normal growth as well as a list of potential growth-related protein biomarker candidates using SWATH-MS and MRMHR during the emmetropization period.

Aim: To evaluate the effects of 0.5% tropicamide on anterior segment parameters with the CASIA2 imaging device in emmetropic, myopic, and hyperopic eyes. Methods: In this prospective study, a total of 125 subjects (34 emmetropic subjects, 57 myopic subjects, and 34 hyperopic subjects) at the Shanghai Eye and ENT Hospital of Fudan University were recruited from June 2021 to September 2021. The 0.5% tropicamide solution was used once every 5 min a total of 5 times for cycloplegia. The anterior segment parameters were recorded by CASIA2 before and after cycloplegia. Changes in anterior segment parameters were compared among the three refractive groups. Results: Crystalline lens rise (CLR) and crystalline lens thickness (CLT) significantly decreased in all three refractive groups after cycloplegia (all p < 0.01). The anterior radius of lens (ARL) and anterior chamber depth (ACD) significantly increased in all three refractive groups after cycloplegia (all p < 0.01). Posterior radius of lens (PRL) significantly increased in hyperopic eyes after cycloplegia (p < 0.01) while it remained unchanged in emmetropic eyes and myopic eyes. Central corneal thickness (CCT), anterior chamber width (ACW), lens decentration (LD), and lens tilt (LT) remained unchanged after cycloplegia in all three refractive groups (all p > 0.05). Changes in CLR, CLT, ARL, PRL, and ACD in hyperopic eyes were greater than those in emmetropic eyes and myopic eyes (all p < 0.05). Conclusion: Apart from various changes in anterior segment parameters after application by 0.5% tropicamide in all three refractive groups, significant changes in CLR, CLT, ARL, PRL, and ACD in hyperopic eyes should be noted for proper clinical interpretation. [ABSTRACT FROM AUTHOR]

Introduction: To investigate changes in refractive error in schoolchildren before and during the coronavirus disease 2019 (COVID-19) pandemic. Methods: This study included 2792 students, who underwent a 3-year follow-up from 2018 to 2020. All participants underwent yearly noncycloplegic refraction and ocular examinations. Time-related changes in sphere, cylinder, and spherical equivalent (SE) measurements in both genders were analyzed. Results: The myopic sphere (− 0.78 ± 1.83 vs. − 1.03 ± 1.91 D; P = 0.025) and SE (− 1.04 ± 1.90 vs. − 1.32 ± 1.99 D; P = 0.015) progressed significantly from 2018 to 2019. Female participants had a significantly greater change in SE than male participants (P < 0.05), and the low hyperopia, emmetropia, and mild myopia groups significantly deteriorated (P < 0.001) from 2018 to 2019. Significant differences in sphere change (− 0.21 ± 0.97 vs. − 0.36 ± 0.96 D; P < 0.001) and SE change (− 0.23 ± 0.99 vs. − 0.38 ± 0.98 D; P < 0.001) were noted between 2019–2018 and 2020–2019, respectively. The respective changes in cylinder were statistically similar (− 0.03 ± 0.53 vs. − 0.05 ± 0.62 D; P = 0.400). Conclusions: The refractive status of schoolchildren showed an increasing myopic shift trend before and during the COVID-19 pandemic. The low hyperopia, emmetropia, and mild myopia groups were more sensitive to environmental changes during COVID-19 than before. The myopic shift was greater in female participants than male participants. [ABSTRACT FROM AUTHOR]

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PURPOSE: Our article aims to assess the accuracy of modified and commonly used formulas of intraocular lens (IOL) power calculation after excimer laser corneal refractive surgery. METHODS: This is a retrospective study, with data retrieved for 50 eyes of 32 patients who underwent uncomplicated cataract surgery after excimer laser corneal refractive surgery. The expected spherical equivalent was calculated using the American Society of Cataract and Refractive Surgeons (ASCRS) IOL power calculator for Shammas and Barrett True‑K, using three‑fourth generation formulas (Haigis‑L, Barrett True‑K no history, and Holladay 2), and using three‑third generation formulas (SRKT, Holladay 1, and Hoffer Q) with single k, as a reference, and adjusting these formulas by calculating the keratometry readings by two methods (Jarade’s index and formula). The mean refractive error and mean absolute refractive error (MARE) were calculated at the 1 postoperative month. RESULTS: When all data was available (eight eyes), 13 formulas were compared. Holladay 1 as modified by Jarade’s index and formula, and Hoffer Q as modified by Jarade’s formula resulted in MARE <0.75D (P < 0.05). In the group of 25 eyes with only ablation available, the formulas with MARE <0.75D were Haigis L, Barrett TK (from ASCRS), Hoffer Q, and the three conventional formulas in Jarade’s index (P < 0.001). In the group of 17 eyes with no available prerefractive data, only Haigis‑L and Barret TK (no history) had a MARE <0.75 D. CONCLUSION: The use of Hoffer Q or Holladay 1, when prerefractive data are available, gives reliable results with Jarade’s index. [ABSTRACT FROM AUTHOR]

Objectives: To investigate and determine the choroidal thickness (CT) in healthy emmetropic Turkish subjects aged between 20 and 40 years using Enhanced Depth Imaging Spectral-Domain Optical Coherence Tomography (EDI-OCT). Methods: This study included 194 eyes of 194 healthy emmetropic subjects. All participants underwent a detailed ophthalmologic examination. Axial length (AL) was measured with optical biometry. CT measurements were performed at subfoveal, 1.0 mm temporal, and 1.0 mm nasal using the EDI-OCT. Central macular thickness (CMT) measurements were also performed at the same time. Participants were divided into two groups; Group 1 (age between 20 and 30 years) and Group 2 (age between 31 and 40 years). CT and CMT were compared among two groups. Results: The mean age of all the subjects was 26.61±6.08 years, the mean AL was 23.44±0.72 mm, and the mean spherical equivalent was -0.11±0.28 Diopter. The mean subfoveal, nasal, and temporal CT was 389.27±86.61 pm, 354.54±86.86 μm, and 368.25±78.69 pm, respectively. Subfoveal and nasal CT of female participants were found thinner than male participants (p=0.013 and p=0.008, respectively). CT and CMT were found similar between Group 1 and Group 2. Conclusion: This study showed that mean subfoveal CT and CMT was 389.27±86.6lpm and 268.I7±I8.76 pm, respec- tively, among healthy emmetropic Turkish subjects. Females had thinner CT in subfoveal and nasal quadrants. In addition, age did not affect CT between 20 and 40 years. [ABSTRACT FROM AUTHOR]

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AIM: To investigate the proportion and characteristic of emmetropia in schoolchildren aged 6-11, especially estimate the normal value of ocular biometric parameters of emmetropia. METHODS: A population-based cross-sectional study was conducted on children aged 6-11y in Shenzhen. Totally, 2386 schoolchildren from two primary schools were involved. The axial length (AL) and the corneal radius of curvature (CRC) were measured by partial coherence laser interferometry. Noncycloplegic refraction and refractive astigmatism (RA) was measured using autorefraction. The axial length-to-corneal radius of curvature ratio (AL/CRC), corneal astigmatism (CA) and spherical equivalent refraction (SER) were calculated. RESULTS: The proportion of emmetropia in elementary school students was 41.30%. This percentage decreased gradually from 6 to 11 years of age and decreased rapidly after 9 years of age. The mean and 95%CI of each parameter were provided for boys and girls aged 6 to 11 years of age with emmetropia according to each age group. The change trend of parameters of boys and girls are similar. After 7 years of age, the AL of non-emmetropia started to increase faster than that of emmetropia. The change trend of AL/CRC was the same as that of AL. The other parameters tend to be stable after 7 years of age. CONCLUSION: The age of 7-9 is an important period for the changes of refractive state and ocular biometric parameters of primary school students, and it is a special focus period for children myopia prevention. The normal value and variation of ocular biometric parameters of emmetropia can provide the basis for the clinical judgment of whether or not children’s ocular biometric parameters obtained by single measurement and changes obtained by multiple measurements are abnormal.

Purpose: To document one‐year changes in refraction and refractive components in preschool children. Methods: Children, 3–5 years old, in the Jiading District, Shanghai, were followed for one year. At each visit, axial length (AL), refraction under cycloplegia (1% cyclopentolate), spherical dioptres (DS), cylinder dioptres (DC), spherical equivalent refraction (SER) and corneal curvature radius (CR) were measured. Results: The study included 458 right eyes of 458 children. The mean changes in DS, DC and SER were 0.02 ± 0.35 D, −0.02 ± 0.33 D and 0.01 ± 0.37 D, while the mean changes in AL, CR and lens power (LP) were 0.27 ± 0.10 mm, 0.00 ± 0.04 mm and − 0.93 ± 0.49 D. The change in the SER was linearly correlated with the baseline SER (coefficient = −0.147, p < 0.001). When the baseline SER was at 1.05 D (95% CI = 0.21 to 2.16), the change in SER was 0 D. The baseline SER was also linearly associated with the change in LP (coefficient = 0.104, p = 0.013), but not with the change in AL (p = 0.957) or with the change in CR (p = 0.263). Conclusion: In eyes with a baseline SER less than +1.00 D, LP loss was higher compared to axial elongation, leading to hyperopic shifts in refraction, whereas for those with baseline SER over this range, loss of LP compared to axial elongation was reduced, leading to myopic shifts. This model indicated the homeostasis of human refraction and explained how refractive development leads to a preferred state of mild hyperopia. [ABSTRACT FROM AUTHOR]

To compare spherical and cylindrical equivalent, and pupillometry measurements between non-amblyopic myopic, emmetropic, and hyperopic children. The study was conducted prospectively and cross-sectionally in a single-centered eye clinic. Three non-amblyopic groups were included in the study: myopic (Myopia Group), emmetropic (Emmetropia Group), and hyperopic (Hyperopia Group) children. The groups were compared in terms of best-corrected visual acuity (BCVA), intraocular pressure (IOP), spherical equivalent (SE), and pupillometry measurements, including minimum dynamic pupillometry, maximum dynamic pupillometry, mesopic pupillometry, and photopic pupillometry. The correlation analysis was also performed between the measurements. We noted significant differences in mean SE values between the three groups and between the paired groups (p<0.001 for all). Similar mean cylindrical equivalent values were observed between the three groups and between the paired groups (p>0.05 for all). The hyperopia group had the lowest mean minimum dynamic pupillometry, maximum dynamic pupillometry, mesopic pupillometry, and photopic pupillometry values (1.97±0.57, 5.23±051, 4.96±0.41, and 3.30±0.54, respectively). We found significant differences in all pupillometry measurements between the three groups (p<0.05 for all). However, similar results were obtained in all pupillometry measurements between the paired comparison of emmetropia and hyperopia groups (p>0.05 for all). We also did not observe any correlation between the pupil diameter and age or gender (p>0.05 for both). Our study might be unique regarding the comparison of pupillometry measurements in non-amblyopic children with refractive errors. Myopia in the pediatric population may have potential pupillometric effects when compared to emmetropia and hyperopia. This should be considered in terms of the clinical relevance of pediatric refractive examination under different illumination conditions. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to determine the influence of age and gender on pupil size under different illuminance conditions in emmetropic and myopic healthy eyes using Keratograph 4 topography. Methods: This study investigated 221 eyes of 221 subjects. After complete ocular examination, the undilated pupil diameters were measured using a pupilometer and Keratograph 4 software (OCULUS, Wetzlar, Germany) with a sequence of 9.8 seconds of the scotopic stimulus (0.1 lux) and 0.2 seconds of the photopic stimulus (150 lux) repeated 5 times automatically. At the end of the procedure, the software provided maximum and minimum values (scotopic and photopic) of the pupil diameter. The age, gender, and refraction related changes of the pupil size were evaluated in different illuminance conditions. Results: Out of 221 participants in this study, 122 (85 female) and 99 (66 female) cases were myopes (MSE: -2.18±1.69 D, age: 26.03±6.98 years) and emmetropes (MSE: -0.11±0.27 D, age: 28.05±10.17 years), respectively. Considering refractive groups, pupil size was larger in myopes, compared to the emmetropes in both illuminance conditions (p

Background: Working dogs, such as police dogs and guide dogs, have important roles in the contemporary society by performing specific and demanding jobs. Ocular health and the maintenance of good visual acuity is imperative to strong work performance and thus human safety. Aim: Assess ophthalmic abnormalities and refractive errors in police and guide dogs in Brazil. Methods: Seventy-one dogs (141 eyes) were evaluated. Ten were guide and 61 were police dogs. Work performance was assessed by a questionnaire to each dog´s handler/owner. All dogs underwent a complete ocular examination, and abnormalities were classified by condition, whether they were active or inactive, and if they were located within the visual-axis. Additionally, 62 dogs were evaluated by streak retinoscopy for refractive errors. Results: Ophthalmic abnormalities were detected in 38 (54%) of the dogs, of which 23 were considered inherited, 25 were considered active, and 10 were located within the visual-axis. Incipient cataracts were the most prevalent abnormality. No guide dog had an abnormality within the visual-axis. The most common refractive error was myopia and the median and interquartile range of -0.75 ± 0.75 diopters, among these, police dogs had -1.0 ± 0.5 diopters, whereas guide dogs +0.38 ± 0.75 diopters. Police dogs tended to be slightly myopic and guide dogs were emmetropic. Conclusion: Despite finding a considerable number of ophthalmic abnormalities and refractive error, work performance was good with no signs of visual impairment in any dog. Regular ophthalmic examinations is advised for working dogs, and exclusion of severely affected dogs from breeding programs is recommended.

Clinical Relevance: Expanding practitioner knowledge regarding potential changes in ocular structure of keratoconic eyes will improve the eye care practice and patient management., Background: This study aimed to compare the difference in choroidal thickness between keratoconus patients and two control groups of myopic-astigmatism and emmetropic subjects., Methods: A case-control study was undertaken which included 50 patients with keratoconus, 50 with myopic-astigmatism, 30 with emmetropia aged between 18 and 39 years. Choroidal thickness was measured at three different locations, including the subfoveal, nasal, and temporal (750 micrometres) to the fovea, using a spectral-domain optical coherence tomography with an enhanced depth imaging technique., Results: The mean spherical equivalents were 0.03 ± 0.05, -3.00 ± 0.2, and -3.00 ± 0.3 dioptre in emmetropic, myopic-astigmatism and keratoconus subjects, respectively. The choroid was significantly thicker in keratoconus patients than in myopic-astigmatism and emmetropic subjects in the subfoveal (396 ± 14, 314 ± 12, and 320 ± 18 μm, respectively, p  < 0.001), temporal (405 ± 14, 317 ± 12, and 328 ± 19 μm, respectively, p  < 0.001) and nasal (376 ± 14, 285 ± 12, and 311 ± 18 μm, respectively; p  < 0.001)., Conclusion: Choroidal thickness is increased in keratoconus. The exact mechanism for choroidal thickening in individuals with keratoconus is unknown, but inflammatory responses could be the reason.

Purpose: To study regional variations in choroidal thickness (CT), luminal thickness and stromal thickness of the choroid, and choroidal vascularity index (CVI) in low myopic and emmetropic eyes using wide‐field optical coherence tomography (OCT). Methods: Sixty‐nine healthy young adults between 20 and 38 years of age participated in this study, including 40 low myopes (mean ± SD spherical equivalent (MSE) refractive error: −3.00 ± 1.39 D, range: −6.00 to −0.62 D) and 29 emmetropes (MSE: −0.05 ± 0.09 D, range: −0.25 to +0.12 D). Wide‐field CT, luminal thickness, stromal thickness and CVI were measured across five eccentricities (fovea, parafovea, perifovea; near‐periphery and periphery) and four quadrants (nasal, temporal, inferior and superior), in vertical and horizontal meridians, while controlling for a range of extraneous factors potentially influencing the CT. Custom‐written software was used to segment and binarize the OCT images. Results: Wide‐field CT, luminal thickness and stromal thickness, averaged across all participants, exhibited significant topographical variation, with the foveal (379 ± 8 µm, 200 ± 4 µm, 179 ± 4 µm, respectively) and peripheral (275 ± 8 µm, 161 ± 4 µm, 114 ± 4 µm, respectively) regions presenting the thickest and thinnest regions (all p < 0.001). Wide‐field CVI showed a progressively higher percentage (greater vascularity) with increasing eccentricity from the fovea towards the periphery (p < 0.001). Macular CT and stromal choroidal thickness were significantly thinner in myopes compared to emmetropes (p < 0.05). Myopes (55.7 ± 0.3%) showed a slightly higher CVI compared with emmetropes (54.4 ± 0.4%) (p < 0.05). Conclusions: Low myopia in young adults was associated with significant choroidal thinning across the macular, but not extramacular regions, with this decrease in choroidal thickness mostly attributed to thinning in the stromal component of the choroid, rather than the luminal (vascular) component. [ABSTRACT FROM AUTHOR]

PurposeSpectral domain optical coherence tomography (OCT) was used to examine the influence of refractive error (RE) on foveal retinal and choroidal thicknesses and scleral canal width (SCW). The performance of the Cirrus and Bioptigen spectral domain OCT instruments was compared in the same eyes.MethodsBoth eyes of 40 healthy human subjects, aged 22 to 38 years, were dilated and imaged, with the Cirrus OCT, using 6-mm five-line rasters collapsed into one line, one centered on the fovea and one bisecting the optic nerve head. Seventy-two of the same eyes were imaged with the Bioptigen OCT, using 6- by 6-mm scans, one centered on the fovea and one on the optic nerve head. Subfoveal retinal and choroidal thicknesses and SCW were measured. Axial lengths (ALs) and REs were obtained using an IOLMaster and a Grand Seiko autorefractor, respectively.ResultsOnly right eyes were included in analyses. Spherical equivalent REs ranged from -12.18 to +8.12 diopters (mean [±SD], -3.44 [±4.06] diopters), and ALs ranged from 20.56 to 29.17 mm (mean [±SD], 24.86 [±1.91] mm). Myopia was associated with relatively thin choroids at the fovea (p < 0.05) but normal retinal thickness. Scleral canal width was significantly correlated with AL as measured with the Bioptigen OCT (p < 0.05). Retinal and choroidal thicknesses recorded with the Bioptigen OCT tended to be smaller than values obtained with the Cirrus OCT (mean difference, 5.63 and 24.76 μm, respectively), whereas the converse was true for the SCW (mean difference, 25.45 μm).ConclusionsThe finding that high myopes tend to have a thinner subfoveal choroid is consistent with previous studies. That high myopia was linked to enlarged scleral canals may help to explain the increased risk of glaucoma in myopia. Observed differences obtained with the Cirrus and Bioptigen instruments urge caution in comparing results collected with different instruments.

For eyes to maintain optimal focus, precise coordination is required between lens optics and retina position, a mechanism that in vertebrates is governed by genetics, visual feedback, and possibly intraocular pressure (IOP). 1 While the underlying processes have been intensely studied in vertebrates, they remain elusive in arthropods, though visual feedback may be unimportant. 2 How do arthropod eyes remain functional while undergoing substantial growth? Here, we test whether a common physiological process, osmoregulation, 3 could regulate growth in the sophisticated camera-type eyes of the predatory larvae of Thermonectus marmoratus diving beetles. Upon molting, their eye tubes elongate in less than an hour, and osmotic pressure measurements reveal that this growth is preceded by a transient increase in hemolymph osmotic pressure. Histological evaluation of support cells that determine the lens-to-retina spacing reveals swelling rather than the addition of new cells. In addition, as expected, treating larvae with hyperosmotic media post-molt leads to far-sighted (hyperopic) eyes due to a failure of proper lengthening of the eye tube and results in impaired hunting success. This study suggests that osmoregulation could be of ubiquitous importance for properly focused eyes. [Display omitted] • Post-molt eye growth in insect larvae involves rapid support cell swelling • Support cell expansion coincides with endogenous hemolymph osmotic changes • Interfering with osmotic processes results in farsightedness and behavioral deficits • Osmoregulation may be of ubiquitous importance for properly focused eyes Rathore et al. find that the post-molt rapid growth of camera-type eyes of Thermonectus marmoratus larvae is driven by osmotic processes. Supporting evidence suggests that endogenous hemolymph osmotic changes correlate with support cell swelling. Manipulating the osmotic environment leads to far-sighted larvae with behavioral deficits. [ABSTRACT FROM AUTHOR]

Introduction:To evaluate the visual and refractive outcomes after implantation of a monofocal aspheric yellow chromophore intraocular lens (Eyecryl Plus ASHFY600, Biotech Vision Care Pvt. Ltd., Ahmedabad, India).Methods:Medical records of patients, who underwent cataract surgery and had intraocular lens implantation, were retrospectively analyzed. One eye of each patient was evaluated. Subjective manifest refraction and visual acuity results at 1 week and 1, 3 and 6 months, and intraoperative and postoperative complications were analyzed.Results:Forty-nine eyes (25 right and 24 left) of 49 patients (31 male and 18 female) were included in the study, At postoperative week 1, best corrected distance visual acuity (CDVA) was significantly increased and within an acceptable range. Uncorrected distance visual acuity (UDVA) and best CDVA were stabilized at the 1st month examination, and there was no significant difference in visual acuity between the 1st month and the 3rd and 6th month examinations. The best CDVA and UDVA at 6th months were 20/25 or better in 93% and 79% of patients, respectively. The spherical equivalent of the manifest refraction was within ± 1.00 D emmetropia in 96% of the patients. No complication occurred during or after surgery.Conclusion:CDVA and UDVA and postoperative refractive results were similar to non-chromophore lenses. The implantation of the Eyecryl Plus ASHFY600 intraocular lens has been evaluated as effective and safe.

PURPOSE: The purpose of this study is to compare the contrast sensitivity function (CSF) between eyes of age-matched individuals with aspheric intraocular lens (IOL) and emmetropia. METHODS: A prospective hospital-based case–control study in South India was conducted to study the CSF in the eyes of patients between the ages of 50–60 years. The CSF was compared between those with emmetropia and those implanted with an indigenous aspheric IOL. Twenty-five consecutive patients were recruited in both groups. The independent sample t-test was used for analysis. RESULTS: The mean age was 53.08 ± 1.96 years and 57.68 ± 2.85 years in normal emmetropes and emmetropic pseudophakic with aspheric IOL, respectively. The mean CSF showed a statistically significant difference (P < 0.000) between the normal emmetropic eyes and pseudophakic eyes with the values being 1.91 and 1.572, respectively. CONCLUSION: The CSF was significantly better in the eyes of age-matched normal emmetropes when compared to those with an aspheric IOL implanted.