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Purpose: This pilot study aimed to compare ocular biometric data obtained from Pentacam AXL and IOL Master 700 in patients with keratoconus who underwent intracorneal ring segment (ICRS) implantation. Method: In this pilot study, patients who underwent ICRS implantation (between 2013 and 2021) at Khalili Hospital were assessed using pre-surgical examinations and biometry and keratometry measurements performed with the Pentacam AXL and the IOLMaster 700. The devices were used in random order, and measurements were conducted by expert operators who were blinded to each other's results. Data were analyzed using SPSS version 23. Result: A total of 21 patients (mean age: 35.47 ± 6.43 years) who underwent ICRS implantation surgery were included. Significant mean differences between Pentacam AXL and IOL Master 700 were observed in anterior chamber depth (ACD), mean keratometry (KM), steep keratometry (K2), and white-to-white distance (WTW) (p < 0.05). No significant differences were found for axial length (AL), flat keratometry (K1), K1 and K2 meridians, or intraocular lens (IOL) power calculated using Haigis and SRK/T formulas (p > 0.05). Conclusion: Significant differences in ACD, KM, K2, and WTW were observed between Pentacam AXL and IOL Master 700 in patients with ICRS implantation, while AL, K1, K1 meridian, K2 meridian, and IOL power calculations (Haigis and SRK/T) showed no differences. These findings underscore the importance of device selection tailored to specific clinical and biometric needs and suggest the necessity of larger studies to confirm these results. [ABSTRACT FROM AUTHOR]

Background: Amblyopia is associated with structural differences in ocular biometrics, but existing studies often lack long-term follow-ups. This study compares three-year changes in ocular biometric components in amblyopic and non-amblyopic eyes. Methods: In this prospective cohort, study data were collected in 2015 and 2018 in Shahroud, northeast Iran. The sample comprised 4968 primary students (9935 eyes), including 4931 non-amblyopic students (9893 eyes) and 37 students with amblyopia (42 eyes). Axial length, keratometry, central corneal thickness, lens thickness, pupil diameter, anterior chamber depth, lens power and vitreous chamber depth were measured using Lenstar LS900. Multilevel mixed-effects regression models were used to determine any association between variables. Results: The mean age of children without and with amblyopia at baseline were 9.7 ± 1.7 and 9.9 ± 1.5 years, respectively. The mean axial elongation in amblyopic and non-amblyopic groups over three years was 0.37 (95% CI: 0.34–0.40) and 0.33 mm (95% CI: 0.31–0.34), respectively (p < 0.001). Amblyopic eyes showed greater axial elongation than non-amblyopic eyes (p < 0.001). Anterior chamber depth was constant in amblyopic eyes while it decreased in non-amblyopic eyes by 0.13 mm. Vitreous chamber depth increased significantly in both groups, with a greater increase observed in the amblyopic eyes (0.36 vs. 0.28 mm) (p < 0.001). Flat and steep keratometry increased significantly in amblyopic eyes (p < 0.001), while it was constant in non-amblyopic eyes. Lens power decreased significantly in both groups (p < 0.001). The increase in the axial length and vitreous chamber depth in the amblyopic eye was greater than in the non-amblyopic eyes (p < 0.001). The spherical equivalent change in both groups was − 0.31 D. Conclusions: Amblyopia was associated with significant changes in key biometric parameters, offering valuable insight into the structural alterations underlying the condition. [ABSTRACT FROM AUTHOR]

This prospective cohort study is aimed to investigate circadian variations in corneal parameters, focusing on sleep-deprived subjects. Sixty-four healthy individuals (age range: 21–76 years) actively participated in this study, undergoing examinations at least five times within a 24-hour timeframe. The analysis encompassed keratometric parameters of the cornea's front (F) and back (B) surfaces, refractive power in flattest and steepest axes (K1, K2), astigmatism (Astig) and its axis (Axis), aspheric coefficient (Asph), corneal pachymetry values of thinnest corneal thickness (Pachy Min) and corneal thickness in the center of the pupil (Pachy Pupil), volume relative to the 3 and 10 mm corneal diagonal (Vol D3, Vol D10) and surface variance index (ISV). Circadian changes were assessed using a hierarchical, mixed-effects linear regression adjusted for age and night shift. A total of 1,636 measurements revealed significant circadian changes in various corneal parameters, including K1 F, K2 F/B, Astig F/B, Asph F/B, Pachy Min/Pupil, Vol D3/10, and ISV (p < 0.0001). Moreover, K1 B exhibited a significant circadian change (p = 0.0002), while Axis F/B remained unchanged. Notably, Corneal thickness peaked before 6 o'clock in the morning and reached its minimum after 12 o'clock. Contrary to previous notions linking corneal diurnal changes with eyelid closure during sleep, our study reveals that these changes persist in the absence of sleep. This research contributes valuable insights into the impact of sleep deprivation on corneal properties, warranting further investigations to deepen our understanding of daily variations in visual quality and guide the planning of refractive eye surgery interventions. [ABSTRACT FROM AUTHOR]

Abstract Purpose This pilot study aimed to compare ocular biometric data obtained from Pentacam AXL and IOL Master 700 in patients with keratoconus who underwent intracorneal ring segment (ICRS) implantation. Method In this pilot study, patients who underwent ICRS implantation (between 2013 and 2021) at Khalili Hospital were assessed using pre-surgical examinations and biometry and keratometry measurements performed with the Pentacam AXL and the IOLMaster 700. The devices were used in random order, and measurements were conducted by expert operators who were blinded to each other’s results. Data were analyzed using SPSS version 23. Result A total of 21 patients (mean age: 35.47 ± 6.43 years) who underwent ICRS implantation surgery were included. Significant mean differences between Pentacam AXL and IOL Master 700 were observed in anterior chamber depth (ACD), mean keratometry (KM), steep keratometry (K2), and white-to-white distance (WTW) (p 0.05). Conclusion Significant differences in ACD, KM, K2, and WTW were observed between Pentacam AXL and IOL Master 700 in patients with ICRS implantation, while AL, K1, K1 meridian, K2 meridian, and IOL power calculations (Haigis and SRK/T) showed no differences. These findings underscore the importance of device selection tailored to specific clinical and biometric needs and suggest the necessity of larger studies to confirm these results.

Abstract Background Amblyopia is associated with structural differences in ocular biometrics, but existing studies often lack long-term follow-ups. This study compares three-year changes in ocular biometric components in amblyopic and non-amblyopic eyes. Methods In this prospective cohort, study data were collected in 2015 and 2018 in Shahroud, northeast Iran. The sample comprised 4968 primary students (9935 eyes), including 4931 non-amblyopic students (9893 eyes) and 37 students with amblyopia (42 eyes). Axial length, keratometry, central corneal thickness, lens thickness, pupil diameter, anterior chamber depth, lens power and vitreous chamber depth were measured using Lenstar LS900. Multilevel mixed-effects regression models were used to determine any association between variables. Results The mean age of children without and with amblyopia at baseline were 9.7 ± 1.7 and 9.9 ± 1.5 years, respectively. The mean axial elongation in amblyopic and non-amblyopic groups over three years was 0.37 (95% CI: 0.34–0.40) and 0.33 mm (95% CI: 0.31–0.34), respectively (p

Accurate preoperative determination of biometric parameters of the eye is the key to successful lens surgery, achieving high and predictable functional results. At the preoperative stage of refractive and cataract surgery, special attention is paid to the study of corneal parameters, in particular, optical power – keratometry. Corneal power is one of the important parameters in calculating intraocular lens power, in the selection of patients for surgery, the diagnosis of corneal diseases, monitoring the dynamics of pathological processes in the cornea, and analyzing postoperative results. Keratometry is based on the fact that the anterior surface of the cornea has mirror properties, and the size of the image reflected from it depends on the curvature of the cornea, which indicates the possibility of calculating its refractive power based on the analysis of the displayed image size. However, the methods and principles of keratometry are diverse. In this review, an analysis of literature devoted to the study of methods for determining the optical power of the cornea is carried out in order to systematize the data. The review highlights the historical aspects of keratometry – from the first attempts to measure the radius of the anterior surface of the cornea to the first ophthalmometer, shows the evolution of ophthalmometry technology – from manual keratometry to keratotopography and keratotomography, separately reflects the principles and formulas for calculating the optical strength of the cornea.

Purpose. To analyze changes of the corneal topography in the long-term period after hyperopic FS-LASIK in patients with low, moderate and high hyperopia.Patients and Methods. This retrospective non-randomized study included data of 174 patients (174 eyes). All patients were performed hyperopic FS-LASIK. All patients were divided into three groups. Group I included patients with low hyperopia (34 eyes), group II included patients with moderate hyperopia (97 eyes), group III included patients with high hyperopia (43 eyes). Before the surgery, the mean cycloplegic spherical equivalent in group I was +1.94 ± 0.61 D, in group II +3.8 ± 2.19 D, in group III +5.7 ± 0.9 D. The stability of corneal topography after surgery was analyzed: mean keratometry, Surface Asymmetry Index (SAI), Surface Regularity Index (SRI). The results were evaluated the day after the surgery, 1 month later, 6 months later, 1 year later and 3 years after the surgery.Results. There were no statistically significant changes in keratometry in groups I and II on the first day after surgery and 3 years later (p > 0.05). In group III, there was a statistically significant decrease in keratometry at 6 months after surgery by 1.35 ± 2.48. D (p = 0.003); however, keratometry remained stable for 3 years thereafter (p > 0.05). In groups I and II, SRI increased at all periods after surgery (p < 0.05), in group II there was an increase in SAI (p < 0.05), in group III, SRI and SAI increased at all periods after surgery (p < 0.05). Although the increase in the indices was statistically significant, it slightly exceeded the normal limits.Conclusions. After correction of low and moderate hyperopia by FS-LASIK, corneal topography remains stable for 3 years after surgery. Correction of high hyperopia is associated with gradual flattening of the cornea within six months after surgery, but then keratometry remains stable for 3 years. It is important to take it into account in clinical practice.

Purpose: To evaluate the effect of upper eyelid blepharoplasty with or without the removal of a strip of orbicularis oculi muscle on corneal topographic parameters, anterior segment parameters, intraocular pressure, and ocular biometry. Method: This prospective study examined 428 eyes of 214 patients with dermatochalasis. Patients were divided into two groups randomly: those who underwent orbicularis oculi muscle excision (Group 1) during blepharoplasty and those who did not (Group 2). Following a detailed ophthalmological examination, corneal topography was used to evaluate the eyes anterior chamber depth (ACD), iridocorneal angle (ICA), keratometry measurements, and corneal astigmatism (CA) in the preoperative and postoperative first and third months. Ocular biometry was used to assess axial length (AXL) and intraocular lens (IOL) power. Goldmann applanation tonometry was used to measure intraocular pressure (IOP). Results: The age and gender distribution between the groups were similar (p = 0.595 and p = 0.493, respectively). In Group 1, the mean steep keratometry (K2) value increased by 1.1 D and the mean CA increased by 0.81 D in the first month (p < 0.001 for both comparisons). The increases in K2 and CA were 0.7 D and 0.63 D, respectively, in Group 2 (p < 0.001 and p = 0.004, respectively). At the postoperative third month, both groups demonstrated statistically significant persistent elevations in K2 and CA values (p < 0.05 for all comparisons) compared to preoperative measurements. Group 1 exhibited statistically significant decreases in both IOL power calculations (0.43 D according to the Barrett formula and 0.40 D according to the SRK/T formula, p < 0.001, for both) and ICA (38.1 ± 4.7° vs. 35.8 ± 4.1°, p = 0.009) measurements at the only one-month postoperative follow-up. IOP, AXL, and ACD measurements did not exhibit any significant changes in both groups at the first and third postoperative months. Conclusion: In addition to changes in keratometry and CA, blepharoplasty with muscle excision significantly decreased IOL power and ICA. It may be beneficial to inquire about recent blepharoplasty history and the surgical technique employed in patients scheduled for cataract or refractive surgery. [ABSTRACT FROM AUTHOR]

Background: To describe the refractive outcomes of eyes with high regular corneal astigmatism undergoing age-related cataract surgery. Methods: Astigmatic patients who underwent cataract surgery with implantation of high-power XY1AT HOYA® toric lenses (IOLs) (≥ T5) between March 2020 and June 2022 were included. Patients were divided into 2 groups based on the type of Total Corneal Astigmatism (TCA) used for the toric IOL calculation: group 1 = TCATK− 700 (TCA measured by the Iol Master 700®) and group 2 = TCAAK− 700 (TCA estimated from the anterior keratometry of the Iol Master 700® and using the Abulafia-Koch regression). The best-uncorrected (UDVA) and corrected (CDVA) distance visual acuity, subjective spherical equivalent (SSEq) and subjective residual cylinder (SRC) were assessed at 1 month. The predictability (centroid [CEPA] and mean absolute error in predicted astigmatism [MAEPA]) of the 2 TCA assessment methods was analyzed. Results: 96 eyes of 74 patients were included. In the whole cohort, the UDVA was 0.14 ± 0.19 logMAR, the CDVA was 0.04 ± 0.07 logMAR. Postoperative SSEq was − 0.24 ± 0.53D. Postoperative SRC was − 0.48 ± 0.56D. The UDVA, SSEq and SRC did not significantly differ between groups. The MAEPA was significantly better with TCAAK−700 compared to TCATK−700: 0.58 ± 0.52D versus 0.65 ± 0.55D (p = 0.01). No significant difference was observed for the CEPA (p(x) = 0.09, p(y) = 0.19). Conclusions: XY1AT HOYA® toric IOLs are a very good alternative even in case of high toricity. Residual astigmatism predictability is high, it would be better with TCAAK− 700. This data should be confirmed with a larger sample of patients. Key messages: What is known: • Toric intraocular lenses allow achieving a significant gain in UCVA in astigmatic patients. • The value of anterior corneal astigmatism correlates with that of posterior corneal astigmatism. What is new: • Residual astigmatism in eyes with high astigmatism implanted with the Vivinex® toric intraocular lens is comparable to that of eyes with intermediate astigmatism using the current digital alignment technology. • The use of the Abulafia-Koch regression allows achieving a greater predictability of postoperative refractive outcomes with the Vivinex intraocular lens compared to the direct measurement of total astigmatism using the Swept-Source OCT technology in high-toricity cases. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the associations of tomographic parameters in anterior segment optical coherence tomography (AS-OCT) with sex and age in a cohort study. Study Design: A cohort design. Materials and methods: AS-OCT data from 391 Japanese participants aged ≥ 35 years were obtained using swept-source OCT. In the cornea, the keratometric power at the flat (Kf) and steep (Ks) meridians, maximum keratometric power (Kmax), keratometric cylinder, spherical power, regular astigmatism, asymmetry, higher-order irregularity (HOI) from the anterior and posterior surfaces, and the central and thinnest corneal thicknesses were evaluated. Also, anterior chamber depth (ACD), lens thickness, crystalline lens rise (CLR), and nasal and temporal angle opening distances at 500 μm from the scleral spur (AOD500) were assessed. Sex differences and age-related changes were analyzed. Results: Women exhibited higher anterior Kf, Ks, and Kmax and lower posterior Kf, Ks, and Kmax than men. The ACD and nasal/temporal AOD500 were shorter in women than in men. The CLR was higher in women, whereas the lens thickness did not differ between the sexes, indicating a more anteriorly positioned lens in women. Age-related changes included increased anterior/posterior HOI, increased lens thickness and CLR resulting in decreased ACD and AOD500. Conclusion: This study reveals sex-related differences in corneal shape, anterior chamber conformation, and lens position, as well as age-related changes in tomographic parameters. ACD, CLR, nasal and temporal AOD500 showed significant sex differences in the 50–70 s, whereas lens thickness showed no difference. [ABSTRACT FROM AUTHOR]

Background: To evaluate the repeatability and agreement of two different ocular biometers and Scheimpflug devices in keratoconus eyes. Methods: This prospective, comparative trial took place at the University hospital, Goethe University, Frankfurt am Main, Germany. We included eyes with keratoconus, one eye per patient, randomly selected. Measurements were taken with Galilei G6 (Ziemer, Switzerland) and Pentacam AXL (Oculus, Germany), three consecutive measurements each. Repeatability and agreement were evaluated for simulated keratometry (simK), astigmatism (simA), maximum keratometry (KMax) and its axis, total keratometry (TCP), axial length (AL), anterior chamber depth (ACD), and thinnest pachymetry (TCT). Results: Both devices showed an excellent repeatability with intra class correlation (ICC) of > 0.97 for all parameters. The 95% limits of repeatability (LoR95%) and agreement (LoA95%) were narrow for all parameters. The Galilei G6 had a narrower LoAR95% for TCT (2.1 μm vs. 4.6 μm), but a wider LoR95% for KMax (0.52D vs. 1.18D). No relevant difference was found for the other parameters. Agreement between the devices was good to moderate, especially for simK and TCP. Conclusions: Both devices show excellent repeatability with narrow LoR95% and high ICC for all parameters. The only relevant difference was found for KMax and TCT in favor of Pentacam AXL and Galilei G6, respectively. Agreement was good to moderate, and most parameters should not be considered interchangeable. [ABSTRACT FROM AUTHOR]

Purpose: To report ocular biometric data of patients undergoing cataract surgery in an eye camp in a city of Northern area of Pakistan. Design: Cross-sectional descriptive study. Place and Duration of Study: A surgical eye camp was set up in the month of September 2022 for 6 days in a private hospital in Skardu. Methods: A total of 119 patients were selected with a non-probability consecutive sampling technique. Ocular biometry of permanent local residents with significant cataracts was included. Incomplete biometry data and coexisting diseases like corneal opacity, pterygium, and severe dry eye causing errors in biometry were excluded. Keratometry was done with an automated refracto-keratometer. Axial length was calculated with an A-scan (ultrasound contact method) and intraocular lens (IOL) power was calculated. Results: A total of 119 patients were selected for biometry among 3908 individuals visiting an eye camp. The mean axial length was 22.13 ± 1.25 SD mm. The mean keratometry readings (K1) was 43.28 ± 1.83 Diopter and (K2) 44.26 ± 1.67 D. The mean intraocular lens (IOL) power was 24.78 ± 3.43 D. The mean K readings were more in males as compared to females (p-value <0.005). There was no significant difference in axial length and IOL power among genders. Conclusion: This study gives normative data on ocular biometric parameters of patients undergoing cataract surgery at high altitudes in Skardu, Pakistan. These biometric values can be used as reference values in the local population. [ABSTRACT FROM AUTHOR]

AIM: To evaluate the reliability of measurements of corneal changes with accommodation in healthy eyes using a Scheimpflug imaging-based system and how these measurements distribute in the normal population.METHODS: Prospective, non-randomized, comparative study including 27 healthy subjects(54 eyes), including emmetropia(13 eyes), myopia(17 eyes), hyperopia(4 eyes)and astigmatism(20 eyes)groups. In all cases, a complete eye examination was performed, including the analysis of corneal changes with different accommodative stimuli(+2.00, 0.00 and -3.00 D)using the Pentacam AXL system. The investigation was structured in 2 phases: repeatability analysis and characterization of accommodation-related corneal changes in healthy populations.RESULTS: In the repeatability analysis, the index of height asymmetry(IHA)showed the greatest variability with the three accommodative stimuli, being the results for the rest of parameters acceptable. The group of emmetropes showed significant differences with accommodative changes in the position of maximum keratometry(Kmax; P

Background: Keratoconus (KCN) is considered a bilateral corneal ectatic disorder characterized by cone-like steepening of the cornea and irregular stromal thinning, which can lead to decreased visual acuity. This study aimed to assess the prevalence and risk factors for the KCN development in Kosovo. Methods and Results: This retrospective study was conducted in the Department of Ophthalmology at the University Clinical Center of Kosovo. The study included 131 respondents, with a total of 262 eyes. Keratometry basis parameters, such as flat keratometry (K1), and steep keratometry (K2), and maximal corneal curvature (Kmax) were determined. Corneal pachymetry was applied to measure the thickness of the cornea. Staging of KCN was done according to the adapted Amsler-Krumeich staging classification system (AK) for anterior data and corneal thickness (CT). Of 262 examined eyes, 240 (91.6%) were KCN eyes, 2(0.8%) were suspect for KCN, and 20(7.6%) were normal. KCN Stage 1 on the AK classification was predominant (P

Abstract Purpose To compare the biometric measurements obtained from the Pentacam AXL Wave, IOLMaster 700, and ANTERION and calculate the recommended intraocular lens power using the Barrett Formulae. Methods This was a retrospective cross-sectional study of patients who underwent biometry using the Pentacam AXL Wave, IOLMaster 700, and ANTERION. Flat keratometry (K1), steep keratometry (K2), anterior chamber depth (ACD), and axial length (AL) from each device were measured and compared. These parameters were used to calculate the recommended IOL powers using the Barrett formula. Results The study included 252 eyes of 153 patients. The IOLMaster had the highest acquisition rate among the two biometers. The Pentacam obtained the shortest mean AL, the IOLMaster measured the highest mean keratometry values, and the ANTERION measured the highest mean ACD. In terms of pairwise comparisons, keratometry and axial length were not significantly different between the Pentacam-IOLMaster and ANTERION-IOLMaster groups, while the rest of the pairwise comparisons were statistically significant. In nontoric and toric eyes, 35–45% of patients recommended the same sphere of IOL power. In another 30–40%, the Pentacam and ANTERION recommended an IOL power one step greater than that of the IOLMaster-derived data. 50% of the study population recommended the same toric-cylinder IOL power. Conclusions The Pentacam AXL Wave, IOLMaster 700, and ANTERION can reliably provide data for IOL power calculations; however, these data are not interchangeable. In nontoric and toric eyes, 35–45% of cases recommended the same sphere IOL power, and in another 30–40%, the Pentacam and ANTERION recommended one-step higher IOL power than the IOLMaster-derived data. In targeting emmetropia, selecting the first plus IOL power is advisable when using the Pentacam and ANTERION to approximate the IOL power calculations recommended by the IOLMaster 700.

AIM: To analyze ocular biometric parameters among candidates for cataract surgery.METHODS: This cross-sectional study was conducted on 4 607 cataract patients(4 607 eyes)in Farabi Eye Hospital, Tehran, Iran from January 2017 to September 2021. Axial length(AL), keratometry(Kf, Ks and Km), and anterior chamber depth(ACD)were assessed using IOLMaster 700. All eyes were categorized into three groups based on AL: short eyes(22 mm25 mm)and ACD as follows: low(3.00 mm3.60 mm).RESULTS: The mean age of patients was 60.3±14.1(range 8-95)years [2 243(48.69%)female and 2 364(51.31%)male]. The AL, ACD and mean keratometry ranges were 23.1 to 23.4 mm, 3.1 to 3.2 mm and 44.50 to 45.00 diopter(D), respectively. The mean amount of ACD in the long eyes group was significantly higher than the normal and short eyes group(P

Purpose: To compare the biometric measurements obtained from the Pentacam AXL Wave, IOLMaster 700, and ANTERION and calculate the recommended intraocular lens power using the Barrett Formulae. Methods: This was a retrospective cross-sectional study of patients who underwent biometry using the Pentacam AXL Wave, IOLMaster 700, and ANTERION. Flat keratometry (K1), steep keratometry (K2), anterior chamber depth (ACD), and axial length (AL) from each device were measured and compared. These parameters were used to calculate the recommended IOL powers using the Barrett formula. Results: The study included 252 eyes of 153 patients. The IOLMaster had the highest acquisition rate among the two biometers. The Pentacam obtained the shortest mean AL, the IOLMaster measured the highest mean keratometry values, and the ANTERION measured the highest mean ACD. In terms of pairwise comparisons, keratometry and axial length were not significantly different between the Pentacam-IOLMaster and ANTERION-IOLMaster groups, while the rest of the pairwise comparisons were statistically significant. In nontoric and toric eyes, 35–45% of patients recommended the same sphere of IOL power. In another 30–40%, the Pentacam and ANTERION recommended an IOL power one step greater than that of the IOLMaster-derived data. 50% of the study population recommended the same toric-cylinder IOL power. Conclusions: The Pentacam AXL Wave, IOLMaster 700, and ANTERION can reliably provide data for IOL power calculations; however, these data are not interchangeable. In nontoric and toric eyes, 35–45% of cases recommended the same sphere IOL power, and in another 30–40%, the Pentacam and ANTERION recommended one-step higher IOL power than the IOLMaster-derived data. In targeting emmetropia, selecting the first plus IOL power is advisable when using the Pentacam and ANTERION to approximate the IOL power calculations recommended by the IOLMaster 700. [ABSTRACT FROM AUTHOR]

Purpose: This retrospective study investigated the impact of corneal parameters on surgically induced astigmatism (SIA) in eyes with prior myopic correction undergoing cataract surgery. Setting: Department of Ophthalmology, San Marino Hospital, San Marino, Republic of San Marino. Design: This case–control study analyzed existing data retrospectively, without randomization or masking. Methods: Eighty eyes divided in group 1 (40 eyes previous underwent refractive surgery for myopia) and group 2 (40 myopic eyes) that underwent cataract surgery with intraocular lens (IOL) implantation were included. SIA was calculated using values from the IOL Master Zeiss 700 and mean pupil power (MPP) derived from the CSO Sirius Topographer (based on 3 mm pupil size) with vectorial analysis from doctor Hill software. Results: No significant difference in SIA was observed between eyes with prior myopic photorefractive keratectomy and the control group (p > 0.05). SIA calculations using the IOL Master and CSO Sirius Tomographer yielded similar results. There was no significant correlation between SIA and axial length, corneal curvature, peripheral corneal thickness, or anterior chamber depth (p > 0.05). However, an inverse correlation was found between SIA and horizontal corneal diameter (p < 0.05). Conclusions: Corneal parameters, such as axial length, corneal curvature, peripheral corneal thickness, and anterior chamber depth, showed no significant influence on SIA. The inverse correlation between SIA and horizontal corneal diameter in study group suggests potential influence of white-to-white distance on SIA. These findings highlight the importance of considering corneal parameters for optimizing surgical outcomes. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to estimate the corneal keratometric index in the eyes of cataract surgery patients who received zero-power intraocular lenses (IOLs). Methodology: This retrospective study analyzed postoperative equivalent spherical refraction and axial length, mean anterior curvature radius and aqueous humor refractive index to calculate the theoretical corneal keratometric index value (nk). Data was collected from 2 centers located in France and Germany. Results: Thirty-six eyes were analyzed. The results revealed a mean corneal keratometric index of 1.329 ± 0.005 for traditional axial length (AL) and 1.331 ± 0.005 for Cooke modified axial length (CMAL). Results ranged from minimum values of 1.318/1.320 to maximum values of 1.340/1.340. Conclusion: The corneal keratometric index is a crucial parameter for ophthalmic procedures and calculations, particularly for IOL power calculation. Notably, the estimated corneal keratometric index value of 1.329/1.331 in this study is lower than the commonly used 1.3375 index. These findings align with recent research demonstrating that the theoretical corneal keratometric index should be approximately 1.329 using traditional AL and 1.331 using CMAL, based on the ratio between the mean anterior and posterior corneal curvature radii (1.22). [ABSTRACT FROM AUTHOR]

Background: To compare results from different corneal astigmatism measurement instruments; to reconstruct corneal astigmatism from the postimplantation spectacle refraction and toric intraocular lens (IOL) power; and to derive models for mapping measured corneal astigmatism to reconstructed corneal astigmatism. Methods: Retrospective single centre study involving 150 eyes treated with a toric IOL (Alcon SN6AT, DFT or TFNT). Measurements included IOLMaster 700 keratometry (IOLMK) and total keratometry (IOLMTK), Pentacam keratometry (PK) and total corneal refractive power in 3 and 4 mm zones (PTCRP3 and PTCRP4), and Aladdin keratometry (AK). Regression‐based models mapping the measured C0 and C45 components (Alpin's method) to reconstructed corneal astigmatism were derived. Results: Mean C0 components were 0.50/0.59/0.51 dioptres (D) for IOLMK/PK/AK; 0.2/0.26/0.31 D for IOLMTK/PTCRP3/PTCRP4; and 0.26 D for reconstructed corneal astigmatism. All corresponding C45 components ranged around 0. The prediction models had main diagonal elements lower than 1 with some crosstalk between C0 and C45 (nonzero off‐diagonal elements). Root‐mean‐squared residuals were 0.44/0.45/0.48/0.51/0.50/0.47 D for IOLMK/IOLMTK/PK/PTCRP3/PTCRP4/AK. Conclusions: Results from the different modalities are not consistent. On average IOLMTK/PTCRP3/PTCRP4 match reconstructed corneal astigmatism, whereas IOLMK/PK/AK show systematic C0 offsets of around 0.25 D. IOLMTK/PTCRP3/PTCRP4. Prediction models can reduce but not fully eliminate residual astigmatism after toric IOL implantation. [ABSTRACT FROM AUTHOR]

Purpose: To determine change in biometric values of eye after fasting and to elucidate whether this change is significant enough to delay the refractive and cataract surgeries during fasting. Study Design: Cross sectional observational. Place and Duration of Study: Eye department, DHQ-UTH, Gujranwala, from April 2021 to May 2021. Methods: Thirty subjects of either gender between 20-40 years of age who participated in both phases were enrolled in this study. Phase 1 was conducted one week before Ramadan and 2nd phase in the last week of Ramadan. After routine ophthalmic examination, keratometric(K) values were obtained with Auto Ref-Keratometer (Canon), while Axial length (AL), Anterior chamber depth (ACD), and Intraocular lens power (IOLp)were obtained from Master-Vu A-scan (Sonomed, Model # MV4500). Data was analyzed using SPSS version 25. Results: Out of 30 participants, 66.6% were female and 33.3%were male with mean age of 29.8 years. Mean K1 increased to 43.03 D during fasting from non-fasting reading of 42.24 D, while Mean K2 increased to 43.87 D during fasting from non-fasting reading of 43.28 D with significant p-value (<0.05). Mean ACD was 3.15mm in non-fasting that also increased to 3.21D in fasting state. Mean AL in non-fasting state was 23.41mm that remains the same in fasting state as well. Mean IOLp in non-fasting state was 21.18D that reduced to 20.42D in fasting state with significant p-value. Conclusion: Fasting increased the keratometry and ACD values with no effect on AL but that reduced overall intraocular lens power [ABSTRACT FROM AUTHOR]

Determining the axial length (AL) of the eye is of significant interest in the management of myopia. However, the devices that allow this value to be obtained are either expensive, for example, optical biometers, or inconvenient for use in pediatric population, such is the case with ultrasound biometers. Therefore, this study aimed to develop a mathematical model for estimating the AL value based on easily obtainable variables, with the novel addition of body height to the analysis. A total of 170 eyes of 85 myopic volunteers (mean age of 10.8 ± 1.45 years, ranging from 7 to 14 years) were included in the analysis. Participants underwent anamnesis, keratometry by NVISION-K 5001, subjective refraction by an optometrist, AL measurement by the Topcon MYAH biometer, and body height measurement. Spearman's correlation test was employed to analyze the relationships between AL and keratometry, spherical equivalent, body height (Sperman's correlation, all r ≥ 0.267, all p < 0.001), and age (Spearman's correlation, p = 0.081). Subsequently, multiple regression analysis was conducted on the variables that demonstrated a previous correlation. The mathematical model obtained permits the estimation of AL based on average keratometry, spherical equivalent, and body height. This model is significant (p < 0.001) and explains 82.4% of AL variability. [ABSTRACT FROM AUTHOR]

AIM:To compare the differences of ocular biometric parameters of age-related cataract between Tibetan and Han ethnic groups, and to analyze the distribution characteristics of ocular biometric parameters in Tibetan cataract patients.METHODS:Retrospective cohort study. A total of 661 patients(1 030 eyes)with age-related cataract confirmed in the hospital between January 2019 and December 2020 were enrolled. The parameters of axial length, anterior chamber depth, keratometry, corneal astigmatism and astigmatic axis were measured by IOL Master 500 in 483 cases(739 eyes)of Tibetan age-related cataract patients and 178 cases(291 eyes)of Han patients.RESULTS:The axial length, anterior chamber depth and corneal astigmatism of the Tibetan patients with age-related cataract were 23.33(22.81, 23.86)mm, 3.04(2.79, 3.30)mm and 0.73(0.47, 1.07)D. The mean keratometry was 43.89±1.35 D. The results indicated that Tibetan cataract patients had shorter axial lengths and smaller keratometry compared to Han patients(all P

Abstract Background The precision of anterior segment biometric measurements in eyes has become increasingly important in refractive surgery. The purpose of this study is to assess the repeatability of the automatic measurements provided by a new spectral-domain optical coherence tomograph (SD-OCT)/Placido topographer (MS-39, CSO) and its agreement with a swept-source OCT (SS-OCT) biometer (CASIA SS-1000, Tomey) in patients with myopia. Methods The right eye of 235 subjects was scanned 3 times with both devices. The evaluated parameters included central corneal radius of the steep meridian, central corneal radius of the flat meridian, mean central corneal radius, thinnest corneal thickness, central corneal thickness, anterior chamber depth, corneal volume and diameter. The intraobserver repeatability of the MS-39 measurements was calculated using intraclass correlation coefficient (ICC), within subject standard deviation, coefficient of repeatability, coefficient of variation and repeated-measures analysis of variance of the 3 repeated measurements. The agreement between the two devices was evaluated by 95% limits of agreement (LoA). Results The majority of the parameters acquired from MS-39 showed high repeatability. The repeatability of corneal diameter was slightly lower than the other measurements, although the ICC remained high. Agreement with the CASIA SS-1000 was good, indicated by the Bland-Altman plots with narrow 95% LoA values for all parameters assessed. Conclusions The high repeatability of automatic measurements by the new device supports its clinical application in eyes with myopia, and the good agreement between the two devices indicates they could be used interchangeably for the parameters evaluated.

Cataracts are characterized by the crystalline lens of the eye becoming cloudy, and dry eye disease (DED) is a multifactorial disease in which the homeostasis of the tear film is lost. As the prevalence of both diseases increases with age, there is a high prevalence of DED among patients who are candidates for cataract surgery. In recent years, cataract surgery has evolved from vision restoration surgery to refractive surgery. To achieve good surgical outcomes, it is necessary to minimize postoperative refractive error in intraocular lens (IOL) power calculation, which requires accurate preoperative keratometry measurements. A stable tear film is important for the accuracy and reproducibility of keratometry measurements, and DED may have a deleterious effect. In this study, original articles that focused primarily on findings related to this topic were evaluated. A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Although appropriate DED diagnoses were not presented in the articles evaluated in this review, it was confirmed that the clinical signs of DED, particularly the shortening of the tear film break-up time (TBUT), negatively impact IOL power calculations. Improvement in these clinical signs might mitigate the negative effects on these calculations. [ABSTRACT FROM AUTHOR]

Cataract surgery is one of the most successful surgical procedures, mainly due to the recent developments in surgical instruments and intraocular lens (IOL) measurements. Understanding the nature of axial length (AL) and keratometry readings (K) in patients with cataracts has significant implications for accurate postoperative IOL size selection. This study aimed to measure AL and K in patients undergoing cataract surgery in Saudi Arabia. This retrospective study included patients who underwent cataract surgery in Madinah, Saudi Arabia. The medical records of adult patients between May 2022 and May 2023 were reviewed, and those with a history of retinal detachment, refractive surgery, or trauma were excluded. The AL and K readings were obtained from the patient’s IOL master results. A total of 691 eyes from 451 patients were included in the analysis. The mean age was 64.54 years old. Most of the patients were women (55%). The mean AL, K1, and K2 values were 23.27, 43.42, and 44.69, respectively. Linear regression analysis was used to measure the relationship between AL and K, revealing an inverse relationship in our findings. As AL increased by one unit, the mean K was estimated to decrease by 0.548, with a 95% confidence interval. Our results demonstrated an inverse relationship between AL and K, implying that when AL increases, K decreases, or the corneal curvature becomes flat. Further studies are needed to investigate the biomechanical mechanisms underlying this relationship. [ABSTRACT FROM AUTHOR]

To evaluate prediction accuracy of pre- and post-DMEK keratometry (K) and total keratometry (TK) values for IOL power calculations in Fuchs endothelial corneal dystrophy (FECD) eyes undergoing DMEK with cataract surgery (triple DMEK). Retrospective cross-sectional multicenter study of 55 FECD eyes (44 patients) that underwent triple DMEK between 2019 and 2022 between two centers in USA and Europe. Swept-source optical coherence tomography biometry (IOLMaster 700) was used for pre- and post-DMEK measurements. K and TK values were used for power calculations with ten formulae (Barrett Universal II (BUII), Castrop, Cooke K6, EVO 2.0, Haigis, Hoffer Q, Hoffer QST, Holladay I, Kane, and SRK/T). Mean error, mean absolute error (MAE), standard deviation, and percentage of eyes within ±0.50/±1.00 diopters (D) were calculated. Studied formulae were additionally adjusted using a method published previously (IOLup1D Method), which increases the IOL power by 1D. While both eyes from the same patient were considered for descriptive statistics, we restricted to one eye per individual (44 eyes for statistical comparisons. MAEs for all formulae were lower for post-DMEK K and TK than pre-DMEK K and TK by an average of 0.24 and 0.47 D, respectively. The lowest MAE was 0.49 D for Kane using post-DMEK TK, and the highest MAE was 1.05 D for BUII using pre-DMEK TK. Most IOLup1D formulae had lower MAEs than pre-DMEK K and TK formulae. The IOLup1D Method should be used instead of pre-DMEK K and TK values for triple DMEK in FECD eyes. Using post-DMEK TK values for cataract surgery after DMEK provides better refractive accuracy than any of the three studied methods used for triple DMEK procedures. [ABSTRACT FROM AUTHOR]

Background: This study aimed to compare keratometry and anterior chamber depth (ACD) changes after XEN implantation in primary open-angle glaucoma (POAG) cases over a 3-month follow-up period. Methods: Twenty patients with POAG who underwent XEN63 implantation, either standalone or combined with cataract surgery, were included. Preoperative data, including best-corrected visual acuity (BCVA), refraction, gonioscopy, ophthalmoscopy, intraocular pressure (IOP) evaluation, and axial length, were collected. Corneal topography and ACD measurements were assessed preoperatively and at postoperative days 1, 7, 15, 30, 60, and 90. Each patient's eye that underwent XEN surgery was included in the study group, with the fellow eye serving as a control. Results: In the study group, there was a significant decrease in IOP after XEN stent implantation at all investigated time intervals (p < 0.05). However, changes in mean ACD did not show statistically significant differences at any follow-up examination in both the study and control groups. Additionally, keratometry readings revealed no significant changes in total astigmatism or steep keratometry values in either group. Conclusions: XEN implantation in POAG cases resulted in a significant decrease in IOP over the 3-month follow-up period. However, there were no significant changes observed in mean ACD or keratometry readings, indicating stability in these parameters post-XEN implantation. These findings suggest that XEN implantation may be an effective option for IOP reduction without affecting corneal curvature or ACD in POAG patients. [ABSTRACT FROM AUTHOR]

Background: The precision of anterior segment biometric measurements in eyes has become increasingly important in refractive surgery. The purpose of this study is to assess the repeatability of the automatic measurements provided by a new spectral-domain optical coherence tomograph (SD-OCT)/Placido topographer (MS-39, CSO) and its agreement with a swept-source OCT (SS-OCT) biometer (CASIA SS-1000, Tomey) in patients with myopia. Methods: The right eye of 235 subjects was scanned 3 times with both devices. The evaluated parameters included central corneal radius of the steep meridian, central corneal radius of the flat meridian, mean central corneal radius, thinnest corneal thickness, central corneal thickness, anterior chamber depth, corneal volume and diameter. The intraobserver repeatability of the MS-39 measurements was calculated using intraclass correlation coefficient (ICC), within subject standard deviation, coefficient of repeatability, coefficient of variation and repeated-measures analysis of variance of the 3 repeated measurements. The agreement between the two devices was evaluated by 95% limits of agreement (LoA). Results: The majority of the parameters acquired from MS-39 showed high repeatability. The repeatability of corneal diameter was slightly lower than the other measurements, although the ICC remained high. Agreement with the CASIA SS-1000 was good, indicated by the Bland-Altman plots with narrow 95% LoA values for all parameters assessed. Conclusions: The high repeatability of automatic measurements by the new device supports its clinical application in eyes with myopia, and the good agreement between the two devices indicates they could be used interchangeably for the parameters evaluated. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to evaluate the impact of clear corneal incisions on astigmatism in patients undergoing cataract surgery. The values of corneal astigmatism before and after surgery were compared, and the difference was analyzed. Methods: A total of 50 patients (50 eyes) with regular astigmatism who underwent phacoemulsification due to cataracts were included in this study. The patient's pre-operative corneal astigmatism, keratometry values, and steep axis were calculated. The operation was performed by the same surgeon, and the phacoemulsification clear corneal incision was keratometrically placed on the steep axis. The results of the pre- and post-operative examinations of patients who underwent cataract surgery were retrospectively analyzed at the 1st month of astigmatism. The values of corneal astigmatism before and after surgery were compared, and the difference was examined. Results: The mean age of the patients was 67.9±6.7 years. Of them, 26 (52%) were women and 24 were men (48%). After surgery, the patient's best-corrected visual acuity was 20/20. Furthermore, their mean keratometric steep axis was 108.6°±34.9°. It was observed that the patients' pre- and post-operative corneal astigmatism were 1.24±0.7 diopter (D) and 0.83±0.58 D, respectively. When the values were compared, a difference of 0.41±0.25 D was observed, which was statistically significant (p<0.001). The mean pre-operative flat keratometry was 42.98±0.78 D, and the mean pre-operative steep keratometry was 44.24±0.78 D. On the other hand, the mean post-operative flat keratometry was 42.99±0.79 D, and the mean post-operative steep keratometry was 43.84±0.74 D. Conclusion: Clear corneal incision during cataract surgery flattens the cornea in the meridian of the incision, which potentially lessens pre-existing astigmatism. This method can reduce glass dependence among patients in secondary hospitals with no available toric intraocular lenses. [ABSTRACT FROM AUTHOR]

Abstract Aim To investigate the correlation of angles α and κ with the refractive and biological parameters in children. Methods This case-series study included 438 eyes of 219 children (males/females = 105/114, age: 3–15 years). Ocular biometric parameters, including axial length, corneal radius of curvature (CR), white-to-white distance (WTW), angle κ and angle α, were measured using IOL Master 700; auto-refraction were assessed under cycloplegia. The eyes were assigned to different groups based on CR, WTW, and gender to compare the angles α and κ, and analyze the correlations between the differences of biological parameters on angles α and κ. Results The means of axial length, CR, WTW, angle α, and angle κ were 23.24 ± 1.14 mm, 7.79 ± 0.27 mm, 11.68 ± 0.41 mm, 0.45 ± 0.25 mm, and 0.27 ± 0.22 mm, respectively. Angle α was correlated with CR and WTW (fixed effect coefficient [FEC] = 0.237, p = 0.015; FEC = -0.109, p = 0.003; respectively), and angle κ also correlated with CR and WTW (FEC = 0.271, p = 0.003; FEC = -0.147, p

Abstract Background Several studies have previously reported the normal values of corneal volume (CV) in various populations, whereas little is known about the CV distribution in healthy young Chinese adults. Our study aimed to investigate the distribution of CV and its relationships with other ocular biometric parameters among healthy young Chinese adults. Methods A total of 1645 eyes from 1645 students at Dali University in Yunnan Province, China, were analyzed. Pentacam was used to measure CV. Central corneal thickness (CCT) and biomechanically corrected intraocular pressure (bIOP) were evaluated by Corvis-ST. Other biometrical parameters, including axial length (AL), keratometry, and white-to-white (WTW) distance, were measured using IOL Master. Results The mean age of the study population was 19.01 ± 0.92 years, and 68.81% of them were women. The CV was normally distributed in the whole sample, with a mean value of 61.23 ± 3.22 mm3. CV and CCT were significantly smaller in the Yi ethnic group than in the Han ethnic group (p

Background Keratoconus (KC) is an ectatic corneal disorder characterized by progressive corneal thinning with myopic astigmatism. Intrastromal corneal ring segments (ICRS) have been broadly selected as a surgical intervention for KC correction to delay the need of keratoplasty. The purpose of this study was to evaluate the corneal densitometry changes in the various annuluses and depths in KC corneas after intrastromal corneal ring segment (ICRS) implantation and to correlate those changes with the other optical and refractive outcomes. Methodology This was a prospective interventional study included 56 eyes of 40 patients with KC who underwent femtosecond laser-assisted Keraring ICRS implantation. The uncorrected and best-corrected visual acuities (UCVA and BCVA), refraction, keratometry, Q-value, thinnest corneal location thickness (TCLT), and corneal densitometry in all the annular zones were assessed preoperatively and 90 days after surgery. Results Following the ICRS implantation after 3 months, when compared to preoperatively, the UCVA, BCVA, improved significantly from 0.21±0.12 and 0.44±0.15 to 0.27±0.12 and 0.58±0.15 (P

Purpose: To assess the corneal parameters in rheumatoid arthritis (RA) patients. Methods: We enrolled 64 patients with RA (32 receiving biologic and 32 receiving conventional drugs) and 32 healthy subjects. Keratometric values (anterior flat [K1], steep [K2], and mean keratometry [Km]), corneal thickness from the pupil center (CCT), apex (ACT), and the thinnest point (TCT), and corneal volume (CV) were measured and compared between the groups. Results: K1, K2, and Km values were significantly higher in the RA group (P = 0.013, P = 0.048, P = 0.027, respectively). The means of CCT, ACT, TCT, and CV were significantly lower in RA patients (P < 0.001, P < 0.001, P < 0.001, P = 0.011, respectively). When we divided RA patients into two groups according to the treatment and compared them to controls, the differences in K1, CCT, ACT, TCT and CV were significant (P = 0.030, P = 0.005, P = 0.001, P = 0.001, P = 0.034, respectively). K1 and CV values of RA-biologic group were similar to the control group (P = 0.205 and P = 0.127, respectively). Conclusion: Biologic agents contribute to the improvement of K1 and CV values in patients with RA.