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PURPOSE To provide a descriptive investigation about relevant features of the crested caracara's eye (Caracara plancus) and bony orbit, as well as provide data for ophthalmic tests. METHODS Morphological observations and the following diagnostic tests were performed: Schirmer tear test (STT), conjunctival flora evaluation, corneal touch threshold (CTT), intraocular pressure (IOP), central corneal thickness (CCT), B-mode ocular biometry, palpebral fissure length (PFL), and corneal diameter (CD) in 19 healthy birds, plus two macerated skulls. Not all birds were used for each test. RESULTS STT: 7.84 ± 3.05 mm/min; CTT: 2.46 ± 1.10 cm; IOP: 19.18 ± 3.07 mmHg; CCT: 0.31 ± 0.02 mm; PFL: 13.32 ± 1.06 mm; CD: 10.26 ± 2.43 mm; Axial globe length: 1.89 ± 0.06 cm; Anterior chamber depth: 0.27 ± 0.06 cm; Lens axial length: 4.55 ± 0.06 cm; Vitreous chamber depth: 1.2 ± 0.07 cm. The most frequent conjunctival bacterial isolates were Corynebacterium sp. (10/23.8%), Staphylococcus sp. (9/21.42%), Streptococcus sp. (7/16.6%), and E. coli (7/16.66%). The large lateral part of the palatine bone likely plays a role in the ventral protection of the globe against the impact of prey. Observed results are generally reflective of increased body mass compared to other Falconiformes, with values approaching those of similar sized Accipitriformes. CONCLUSIONS These data may help veterinarians recognize peculiar morphologic features and perform a more accurate diagnosis of eye diseases of this avian species.

Although reduced ambient lighting (“dim” light) can cause myopia in emmetropizing chicks, it does not necessarily lead to myopic changes in emmetropizing rhesus monkeys. Because myopia is rarely spontaneous, a question remained whether dim light would hasten the progression of visually induced myopia. To determine the effects of dim light on the development of and recovery from form-deprivation myopia (FDM), seven 3-week-old infant rhesus monkeys were reared under dim light (mean ± SD = 55 ± 9 lx) with monocular diffuser spectacles until ~154 days of age, then maintained in dim light with unrestricted vision until ~337 days of age to allow for recovery. Refractive errors, corneal powers, ocular axial dimensions and sub-foveal choroidal thicknesses were measured longitudinally and compared to those obtained from form-deprived monkeys reared under typical laboratory lighting (504 ± 168 lx). Five of the seven subjects developed FDMs that were similar to those observed among their normal-light-reared counterparts. The average degree of form-deprivation-induced myopic anisometropia did not differ significantly between dim-light subjects (−3.88 ± 3.26D) and normal-light subjects (−4.45 ± 3.75D). However, three of the five dim-light subjects that developed obvious FDM failed to exhibit any signs of recovery and the two monkeys that were isometropic at the end of the treatment period manifest abnormal refractive errors during the recovery period. All refractive changes were associated with alterations in vitreous chamber elongation rates. It appears that dim light is not a strong myopiagenic stimulus by itself, but it can impair the optical regulation of refractive development in primates.

Background: Myopia is the most prevalent ocular disorder in the world, and corneal parameters have been regarded as key ocular biometric parameters determining the refractive status. Here, we aimed to determine the association of genome-wide association study-identified corneal curvature (CC)-related gene variants with different severity of myopia and ocular biometric parameters in Chinese population.Methods: Total 2,101 unrelated Han Chinese subjects were recruited, including 1,649 myopia and 452 control subjects. Five previously reported CC-associated gene variants (PDGFRA, MTOR, WNT7B, CMPK1 and RBP3) were genotyped by TaqMan assay, and their association with different myopia severity and ocular biometric parameters were evaluated.Results: Joint additive effect analysis showed that MTOR rs74225573 paired with PDGFRA rs2114039 (P = .009, odds ratio (OR) = 4.91) or CMPK1 rs17103186 (P = .002, OR = 13.03) were significantly associated with higher risk in mild myopia. Critically, mild myopia subjects had significantly higher frequency in MTOR rs74225573 C allele than high myopia subjects (P = .003), especially in male subjects (P = .001, OR = 0.49). High myopia subjects carrying MTOR rs74225573 C allele have significant flatter CC (P = .035) and longer corneal radius (P = .044) than those carrying TT genotype.Conclusion: This study revealed that male high myopia subjects are more prone to carry CC-related MTOR rs74225573 T allele, whereas mild myopia subjects are prone to carry the C allele. MTOR rs7422573 variant could be a genetic marker to differentiate mild from high myopia in risk assessment.Abbreviations: ACD: anterior chamber depth; AL: axial length; AL/CR: axial length/corneal radius ratio; ANOVA: analysis of variance; CC: corneal curvature; CCT: central corneal thickness; C.I.: confidence interval; CMPK1: cytidine/uridine monophosphate kinase 1; CR: corneal radius; D: diopter; GWAS: genome-wide association studies; HWE: Hardy-Weinberg equilibrium; LT: lens thickness; MIPEP: mitochondrial intermediate peptidase; MTOR: mechanistic target of rapamycin kinase; OR: odds ratio; PDGFRA: platelet-derived growth factor receptor-α; RBP3: retinol-binding protein 3; SD: standard deviation; SE: spherical equivalence; SNTB1: syntrophin beta 1; VCD: vitreous chamber depth; VIPR2: vasoactive intestinal peptide receptor 2; WNT7B: wingless/integrated family member 7B.

To develop an equation for estimating the vitreous chamber volume in pseudophakic patients based on the axial length of the eye. A consecutive series of patients who underwent vitrectomy surgery for a macular hole or an epiretinal membrane were enrolled. The inclusion criteria were as follows: having pseudophakia, being older than 50 years, and having eyes with axial length ranging from 21 to 26 mm. Before the surgery, the axial length was measured using optical biometry. Pars plan vitrectomy was performed, and, after the fluid-air exchange, the vitreous chamber was filled with Brilliant Blue G (0.005%). The infused volume of each eye was recorded. Then, epiretinal membrane peeling or internal limiting membrane peeling and a new fluid-air exchange were performed. Main outcomes and measures were the vitreous chamber volume and axial length. The sample consisted of 112 patients. The mean [standard deviation (SD), range] age was 71 years (7, 53–90). Sixty-five individuals (58%) were women. In 58 (51.8%) patients, surgery was performed on the right eye. The mean (SD; range) axial length was 23.78 mm (0.93; 21.55–25.26), and the mean (SD; range) vitreous chamber volume was 4.96 mL (0.69; 3.60—6.40). Pearson’s correlation coefficient (r = 0.950; p

The field related to the visual system of wild animals is deeply scarce. Settling anatomical and physiological parameters for these animals is still a descriptive vision for Bradypus variegatus (Schinz, 1825). Thus, our research aimed to determine patterns of normal eye for this species. For this purpose, eight eye bulbs were dissected from the carcasses obtained by natural death, and then performed an overview of ocular anatomical. Rebound tonometry (RBT) and ocular B-mode ultrasonography were also applied for eight eyes in four animals from “Parque Estadual Dois Irmãos”, situated in the city of Recife, state of Pernambuco (PE), to estimate the intraocular pressure and ocular ecobiometry. The ocular morphology of sloth is similar as described for other species, however, with some peculiarities. They present a third eyelid emerging in the nasal region of the inferior conjunctival sac and retina and also contain little differentiated blood vessels. Medium the intraocular pressure (IOP) was 4.25mmHg with no difference for both eyes. Ultrasonography of ocular anatomy is also similar regarding other species. Ecobiometric patterns were evaluated to determine the anterior chamber depth, lens width, vitreous chamber depth, and axial length (AL) of ocular globe and the averaged as shown 0.63±1.11mm, 3.73±0.24mm, 6.15±0.41mm, 3.70±0.27mm, and 8.48±0.22mm, respectively. There was no difference between the right and left eyes. The RBT and ocular B-mode ultrasonography are fast exams and easy for animal testing. This study contributed to the characterization of ocular anatomy as well as settling medium values of IOP and intraocular measures; however, further research on physiology and histology is necessary to better understand the visual function of the species. RESUMO: O campo de estudo relacionado ao sistema visual de animais silvestres é muito escasso. Estabelecer parâmetros anatômicos e fisiológicos para estes animais ainda está restrito a uma visão descritiva, assim ocorre em Bradypus variegatus (Schinz, 1825). Diante deste fato, objetivou-se com este estudo determinar padrões de normalidade oftálmica nesta espécie. Para isto foram dissecados oito bulbos oculares de cadáveres obtidos por morte natural e realizada a descrição anatômica ocular. Além disso, foram realizadas tonometria de rebote (TonoVet®) e ultrassonografia em modo B em oito olhos de quatro animais provenientes do Parque Estadual Dois Irmãos, Recife/PE, para avaliação da pressão intraocular e realização da ecobiometria ocular. A anatomia ocular do bicho-preguiça é semelhante à descrita para outras espécies com algumas particularidades. Apresentam uma terceira pálpebra emergindo na região nasal do saco conjuntival inferior e retina com vasos sanguíneos pouco diferenciados. A pressão intraocular média foi de 4,25mmHg não havendo diferença entre os olhos direito e esquerdo. A anatomia ocular ultrassonográfica é semelhante à encontrada para outras espécies. Os padrões ecobiométricos obtidos foram: profundidade da câmara anterior, espessura do cristalino, diâmetro do cristalino, profundidade da câmara vítrea e comprimento axial do bubo ocular com tamanhos médios de 0,63±1,11mm, 3,73±0,24mm, 6,15±0,41mm, 3,70±0,27mm e 8,48±0,22mm, respectivamente. Não houve diferença entre os olhos direito e esquerdo. A tonometria de rebote e a ultrassonografia ocular em modo B são exames de rápida e fácil execução, sendo bem tolerados pelos animais. Este estudo contribuiu para a caracterização anatômica ocular e para o estabelecimento de valores médios da pressão intraocular e das medidas intraoculares, no entanto são necessárias outras pesquisas na área da fisiologia e histologia para melhor compreensão da função visual da espécie.

Purpose: Assess morphophysiological and functional features of the structure of the zonula lens fibers on the basis of an in-depth analysis consistent with the laws of mechanics. Define the purpose and scope of each portion of the zonula lens fibers. To analyze the results of the research of studies on the structure of the zonula of Zinn in the different authors of the last two centuries. Identify misconceptions about the work of this executive mechanism of accommodation in different phases of accommodation, this includes the uneven accommodation in different meridians. Determine the incorrectness of those theories of accommodation, which are based on erroneous ideas about the functioning of different portions of the zonula fibers. Methods: Theoretical analysis based on the laws of mechanics and assessment of the results of interdisciplinary research by different authors in the field of structural and functional features of the Zinn's zonule of the lens in different phases of accommodation. Results: The lens’s ciliary belt has been found to have three major portions of fiber that perform different functions. Powerful anterior portion of fibers is attached to the anterior surface of the lens bag in a segmented mannered a powerful posterior portion of fibers is attached to the posterior surface of the lens evenly around the circumference and like a cobweb covering the surface of the vitreous chamber. Both these filaments in the eye don’t cross and in all phases of accommodation remain

Purpose: Near work has been linked with myopia development; however, the underlying mechanism remains unclear. Small increases in axial length during accommodation have previously been reported in adults, and therefore, this study aimed to examine if accommodation-induced changes in ocular biometry also occur in school-aged children. Methods: A range of ocular biometric measurements were captured during brief accommodation tasks at four demands (0, 3, 6, and 9 D), in a group of 87 non-myopic, school-aged children using a Badal optometer mounted to a non-contact optical biometer (Zeiss IOLMaster 700, https://www.zeiss.com/meditec/int/product-portfolio/optical-biometers/iolmaster-700.html). Reliable biometry measurements and active accommodation were observed for 76 participants who were included in the analysis. The average central corneal thickness (CCT), anterior chamber depth (ACD), crystalline lens thickness (LT), anterior segment length (ASL), vitreous chamber depth (VCD), and axial length (AL) were determined for each accommodation demand. Raw measurements of AL and VCD were corrected to account for the effect of LT changes during accommodation. Results: On average, AL increased with increasing levels of accommodation (p = 0.005). The mean (SEM, standard error of the mean) AL increase from 0 D to the 3, 6, and 9 D demands was 4 (1), 8 (1), and 15 (2) µm, respectively. All other biometric parameters, except CCT, changed significantly during accommodation. LT and ASL increased, and ACD and VCD decreased significantly with increasing accommodation (all p ≤ 0.02). A longer baseline AL was associated with greater levels of accommodation-induced axial elongation at the 9 D demand (p Conclusions: AL increased significantly during accommodation in children, consistent with previous findings in adults up to a 6 D demand. AL continued to increase for higher levels of accommodation (9 D demand), which children may experience during near tasks. These findings provide further insights into potential mechanisms linking near work, axial elongation, and myopia development. However, no myopic children participated in this experiment; therefore, further research is required.

We present patient characteristics and follow-up results of cases with anterior chamber dexamethasone implant migration. The common feature of all six presented cases was vitrectomized eyes. Four of the patients had sutured intraocular lens (IOL) implantation due to complicated cataract surgery, one had combined retinal detachment surgery with sutured IOL implantation, and one had vitrectomy for diabetic intravitreal hemorrhage cleaning and uncomplicated cataract surgery. Anterior chamber implant migration caused corneal edema in all cases and elevated intraocular pressure in three cases. In two cases, the dexamethasone implant was directed into the vitreous cavity after maximum pupillary dilation and corneal manipulation with cotton tip applicator with the patient in reverse Trendelenburg position. There was no other complication until dexamethasone implant degradation, with clear cornea at final examination. In two cases, the implant was removed from the anterior chamber by aspiration, but keratoplasty surgery was planned due to endothelial cell loss and persistent corneal edema during follow-up. In the last two cases, the dexamethasone implant was redirected into the vitreous chamber with a 23-gauge catheter and anterior chamber maintainer but they migrated into the anterior chamber again. In one of these patients, the implant was aspirated by catheter and corneal transplantation was performed due to corneal edema, while the other patient’s implant was redirected into the vitreous chamber with no further anterior migration. The risk of dexamethasone implants migrating into the anterior chamber of vitrectomized eyes and those with sutured IOL implantation should be kept in mind and the patient should be informed and advised to see an ophthalmologist immediately before permanent corneal endothelial damage occurs. © 2020 by Turkish Ophthalmological Association.

Purpose: To determine the distribution of ocular biometric components, including axial length, lens thickness, and vitreous chamber depth, their relationship with personal characteristics, and spherical equivalent refraction after adjusting axial length and vitreous chamber depth for personal characteristics. Methods: Among 6- to 12-year-old children, urban subjects were selected using random cluster sampling, and in rural areas, all eligible subjects were considered for enrollment. Ocular biometrics were measured using BioGraph. Data were summarized as mean and 95% confidence intervals. Linear regression was used to investigate the relationships between the study variables. Results: Data from 4938 children were analyzed. Mean axial length, lens thickness, and vitreous chamber depth were 23.02 (95% confidence interval: 22.97–23.07) mm, 3.48 (95% confidence interval: 3.47–3.49) mm, and 20.63 (95% confidence interval: 20.59–20.66) mm, respectively. According to the multiple linear regression model, axial length and vitreous chamber depth associated positively with height (β = 0.020, P Conclusion: This cross-sectional study showed a general pattern of ocular biometric components. The axial length value was almost similar to European countries, but less than that in the Eastern and Southeast Asian populations. By increasing age, axial length and vitreous chamber depth increased while lens thickness and spherical equivalent decreased. Among all ocular biometric components, axial length was strongest determinant for spherical equivalent.

Background To evaluate the intraocular pressure (IOP), anterior chamber angle (ACA), and globe biometric parameters in β-thalassemia major children and the correlations of these changes. Materials and methods Eighty-four eyes were included (42 eyes of thalassemia patients and 42 eyes of control). All participates underwent head circumference and height measurements, full ophthalmic examination, anterior segment optical coherence tomography (AS-OCT), and A-scan biometry. Results The temporal angle of anterior chamber (T-ACA) was significantly narrower in thalassemia patients with p value = 0.008. While the nasal angle showed a nonsignificant narrowing with p value = 0.153. This narrowing was positively correlated with the height, and negatively correlated with the head circumference. Intraocular pressure was statistically higher in thalassemia patients with p value = 0.000. The increased IOP was positively correlated with the head circumference and the lens thickness (LT) and negatively correlated with T-ACA, axial length (AL), vitreous chamber depth (VCD), and anterior chamber depth (ACD). Axial length, ACD, and VCD significantly decreased with p value = 0.000 for all with a positive correlation with the height and a negative correlation with the head circumference. The LT increased in thalassemia group with p value = 0.000. This increase was positively correlated with the head circumference and negatively with the height. Also, there was steeper corneal curvature in thalassemia group with p value = 0.023 and 0.015 (for K1 and K2, respectively). No significant change was observed in corneal thickness in both groups with p value = 0.810. Conclusion Narrower T-ACA, increased IOP, shorter (AL, VCD, and ACD), steeper corneal curvature, and thicker lens were found in thalassemia patients. How to cite this article El-Haddad NSM. Anterior Chamber Angle, Intraocular Pressure, and Globe Biometric Parameters in the Children with β-Thalassemia Major. J Curr Glaucoma Pract 2020;14(1):30–36.

The interface between silicone oil and saline layers in a three-dimensional model of the eye chamber was studied under different eye-like saccadic motions in order to determine the stability of the interface and propensity for emulsification in the bulk. The effect of level of fill, saccade amplitude, angular velocity, latency time, and orientation were investigated experimentally in spherical flasks with internal diameters 10, 28, and 40 mm, as well as a 28 mm diameter flask with an indent replicating the lens or the presence of a buckle. The deformation of the interface was quantified in terms of the change in its length in two-dimensional images. The deformation increased with Weber number, We, and was roughly proportional to We for We > 1. The presence of the lens gave rise to higher deformation near this feature. In all cases emulsification was not observed in either bulk fluid. The velocity profile in the spherical configuration was mapped using particle imaging velocimetry and is compared with an analytical solution and a short computational fluid dynamics simulation study. These confirm that the saccadic motion induces flow near the wall in the saline layer and significantly further into the chamber in the silicone oil. Surfactants soluble in the aqueous and oil phases reduced the interfacial tension, increasing deformation but did not lead to emulsification in the bulk.

PURPOSE Exposure to narrow-band red light, which stimulates only the long-wavelength sensitive (LWS) cones, slows axial eye growth and produces hyperopia in tree shrews and macaque monkeys. We asked whether exposure to amber light, which also stimulates only the LWS cones but with a greater effective illuminance than red light, has a similar hyperopia-inducing effect in tree shrews. METHODS Starting at 24 ± 1 days of visual experience, 15 tree shrews (dichromatic mammals closely related to primates) received light treatment through amber filters (BPI 500/550 dyed acrylic) either atop the cage (Filter group, n = 8, 300-400 human lux) or fitted into goggles in front of both eyes (Goggle group, n = 7). Non-cycloplegic refractive error and axial ocular dimensions were measured daily. Treatment groups were compared with age-matched animals (Colony group, n = 7) raised in standard colony fluorescent lighting (100-300 lux). RESULTS At the start of treatment, mean refractive errors were well-matched across the three groups (p = 0.35). During treatment, the Filter group became progressively more hyperopic with age (p

Intraocular injection of silicone oil as a tamponade agent is a commonly used technique for the treatment of retinal detachment. An incompletely understood phenomenon which can occur after injection is the migration of silicone oil from the vitreous chamber to the intracranial space. Because the appearance of silicone oil can mimic hemorrhage or other pathologies on CT and MRI, careful comparison with prior studies is necessary to avoid unnecessary follow-up studies. We report a case of intracranial migration of intraocular silicone oil following repetitive head trauma. Keywords: Silicone oil, Intracranial hemorrhage, Trauma, Retinal detachment

The purpose of this study was to evaluate the effect of interrupting negative lens wear for short periods early or late during the development of lens-induced myopia in marmosets. Sixteen marmosets were reared with a −5D contact lens on their right eye (plano on contralateral eye) for 8 weeks. Eight marmosets had lenses removed for 30 mins twice/day during the first four weeks (early interruption) and eight during the last four weeks (late interruption). Data were compared to treated controls that wore lenses continuously (N = 12) and untreated controls (N = 10). Interocular differences (IOD) in vitreous chamber (VC) depth and central and peripheral mean spherical refractive error (MSE) were measured at baseline and after four (T4) and eight (T8) weeks of treatment. Visual experience during the interruptions was monitored by measuring refraction while marmosets were seated at the center of a 1 m radius viewing cylinder. At T4 the eyes that were interrupted early were not different from untreated controls (p = 0.10) and at T8 had grown less and were less myopic than those interrupted later (IOD change from baseline, VC: +0.07 ± 0.04 mm vs +0.20 ± 0.03 mm, p 4 − T0: 3.67 ± 1.1 µm/day, T8 − T4: 3.56 ± 1.3 µm/day p = 0.96). Peripheral refraction was a predictive factor for the amount of myopia developed only when the interruption was not effective. In summary, interrupting hyperopic defocus with short periods of myopic defocus before compensation occurs prevents axial myopia from developing. After myopia develops, interruption is less effective.

PURPOSE: To evaluate the ocular biological parameter difference between scleral corneal cross-linking (CXL) and control eyes in rhesus monkeys by using a rebound tonometer, A-scan ultrasonography, retinoscopy, optical coherence tomography, and electroretinography (ERG). METHODS: Six rhesus monkeys were used in this study, with ages ranging from 3 to 3.5 years. One eye of each rhesus monkey was randomly selected to receive riboflavin/ultraviolet-A CXL in the temporal quadrant of the equatorial sclera and the contralateral eye served as an intra-individual control. The ocular biological parameters were repeatedly measured in both eyes of the monkeys before scleral CXL and 1 week, 1 month, and 3 months postoperatively. RESULTS: The intraocular pressure, refractive state, total axial length, and axial dimensions of the anterior chamber, crystalline lens, vitreous chamber, and central corneal thickness were not statistically significantly different between the control and cross-linked specimens at the different time periods (each P > .05). No obvious changes in the waveform of the standard full-field ERGs were observed in the control and cross-linked specimens. There were no statistically significant differences between the control and cross-linked specimens in the dark-adapted 0.01 ERG, the dark-adapted 3.0 ERG, the light-adapted 3.0 ERG, and the amplitudes of the a-wave and b-wave for the different time periods (each P >.05). CONCLUSIONS: The scleral CXL laboratory technique might not significantly affect the ocular biological parameters of the rhesus monkey in the early postoperative period, but long-term effects and histological changes still need to be investigated further. [ J Refract Surg . 2019;35(5):333–339.]

We describe an analysis strategy to obtain ultrasonography-matched axial dimensions of small animal eyes using the LenStar biometer. The LenStar optical low-coherence reflectometer is an attractive device for animal research due to its high precision, non-invasiveness, and the ability to measure the axial dimensions of cornea, anterior chamber, lens, vitreous chamber, and axial length. However, this optical biometer was designed for clinical applications in human eyes and its internal analysis provides inaccurate values when used on small eyes due to species-dependent differences in refractive indices and relative axial dimensions. The LenStar uses a near infrared light source to measure optical path lengths (OPLs) that are converted by the LenStar’s EyeSuite software into geometrical lengths (GLs) based on the refractive indices and axial dimensions of the human eye. We present a strategy that extracts the OPLs, determines refractive indices specific for the small animal eye of interest and then calculates corrected GLs. The refractive indices are obtained by matching the LenStar values to ultrasonography values to ultrasonography values in the same eyes. As compared to ultrasounography, we found that the internal calculations of the LenStar underestimate the axial dimensions of all ocular compartments of the tree shrew eye: anterior segment depth by 6.17 ± 4.50%, lens thickness by 1.37 ± 3.06%, vitreous chamber depth by 29.23 ± 2.35%, and axial length by 10.62 ± 1.75%. Using tree shrew-specific refractive indices, the axial dimensions closely matched those measured by ultrasonography for each compartment. Our analysis strategy can be easily translated to other species by obtaining a similar paired data set using ultrasonography and LenStar, and applying our step by step procedures.

Noninfectious uveitis is a potentially blinding ocular condition that often requires treatment with corticosteroids to prevent inflammation-related ocular complications. Severe forms of uveitis such as panuveitis that affects the whole eye often require a combination of topical and either regional or systemic corticosteroid. Regional corticosteroids are currently delivered inside the eye by intravitreal injection (e.g. Ozurdex®, an intravitreal dexamethasone implant). Intravitreal injection is associated with rare but potentially serious side effects, including endophthalmitis, retinal and vitreous hemorrhage, and retinal detachment. Subconjunctival (SCT) injection is a less invasive option that is a common route used for post-surgical drug administration and treatment of infection and severe inflammation. However, it is the water soluble form of dexamethasone, dexamethasone sodium phosphate (DSP), that has been demonstrated to achieve high intraocular penetration with subconjunctival injection. It is difficult to load highly water soluble drugs, such as DSP, and achieve sustained drug release using conventional encapsulation methods. We found that use of carboxyl-terminated poly(lactic-co-glycolic acid) (PLGA) allowed encapsulation of DSP into biodegradable nanoparticles (NP) with relatively high drug content (6% w/w) if divalent zinc ions were used as an ionic “bridge” between the PLGA and DSP. DSP-Zn-NP had an average diameter of 210 nm, narrow particle size distribution (polydispersity index ~0.1), and near neutral surface charge (−9 mV). DSP-Zn-NP administered by SCT injection provided detectable DSP levels in both the anterior chamber and vitreous chamber of the eye for at least 3 weeks. In a rat model of experimental autoimmune uveitis (EAU), inflammation was significantly reduced in both the front and back of the eye in animals that received a single SCT injection of DSP-Zn-NP as compared to animals that received either aqueous DSP solution or phosphate buffered saline (PBS). DSP-Zn-NP efficacy was evidenced by a reduced clinical disease score, decreased expression of various inflammatory cytokines, and preserved retinal structure and function. Furthermore, SCT DSP-Zn-NP significantly reduced microglia cell density in the retina, a hallmark of EAU in rats. DSP-Zn-NP hold promise as a new strategy to treat noninfectious uveitis and potentially other ocular inflammatory disorders.

In chicks, axial length and choroidal thickness undergo circadian oscillations. The choroid is innervated by both branches of the autonomic nervous system, but their contribution(s) to these rhythms is unknown. We used two combination lesions to test this. For parasympathectomy, nerve VII was sectioned presynaptic to the pterygopalatine ganglia, and the ciliary post-ganglionics were cut (double lesion; n = 8). Triple lesions excised the sympathetic superior cervical ganglion as well (n = 8). Sham surgery was done in controls (n = 7). 8–14 days later, axial dimensions were measured with ultrasonography at 4-h intervals over 24 h. Rhythm parameters were assessed using a “best fit” function, and growth rates measured. Both types of lesions resulted in ultradian (> 1 cycle/24 h) rhythms in choroidal thickness and axial length, and increased vitreous chamber growth (Exp-fellow: double: 69 µm; triple: 104 µm; p

PURPOSE MRI is becoming increasingly available within the veterinary profession, and eyes are frequently included as part of a cranial study. The advantages of volumetric imaging are numerous, when compared to traditional two-dimensional imaging, and could be utilised within the veterinary setting. This report describing the normal MRI appearance of the canine eye, aimed to establish a standard reference range on a T1w volumetric acquisition. METHOD This study retrospectively assessed 62 eyes from 31 dogs that had undergone MRI at the Small Animal Hospital, Langford Vets, University of Bristol between 2016 and 2018 using a standardised MRI protocol. Dogs were excluded if they had presented with any reported ocular or orbital abnormalities. Measurements were performed from the 3D T1w volumetric sequence by a single observer using a previously published technique. RESULTS Mean axial globe length was 2.13 cm and equatorial width 2.16 cm. Mean anteroposterior depth of the anterior chamber was 0.40 cm and 0.97 cm for the vitreous chamber. The mean anteroposterior and equatorial distance of the lens was 0.75 cm and 1.15 cm, respectively. Mean optic nerve width was 0.15 cm, and the mean width of the entire optic nerve sheath was 0.43 cm. Statistically significant relationships were noted between age and axial globe length and both lens dimensions. Highly significant relationships were noted between all variables, except lens dimensions and body weight Conclusion: This study provides reference values to assist in the interpretation of ocular structures during MRI on a T1w volumetric acquisition.

SIGNIFICANCE This research found that anterior and posterior biometrics differ in many aspects between fellow eyes of anisometropic children. This might shed light on the mechanisms underlying the onset and progression of anisometropia and myopia. PURPOSE This study aimed to investigate the ocular biometric parameters, peripheral refraction, and accommodative lag of fellow eyes in anisometropic children. METHODS Anisometropic children were recruited. Axial length (AL), vitreous chamber depth (VCD), central corneal thickness, anterior chamber depth (ACD), lens thickness (LT), simulated K readings, central and peripheral refractive errors, and accommodative lag were measured in both eyes. The subfoveal choroidal thickness, average choroidal thickness, and choroid vessel density of the 6 × 6-mm macular area were measured by optical coherence tomography. RESULTS Thirty-two children aged 11.1 ± 1.7 years were enrolled. The average degree of anisometropia was 2.49 ± 0.88 D. The AL, VCD, ACD, and simulated K reading values were significantly larger in the more myopic eyes, whereas the LT value was significantly smaller. Subfoveal choroidal thickness (P = .001) and average choroidal thickness (P = .02) were smaller in the more myopic eyes than in the contralateral eyes, whereas choroid vessel density (P = .03) was larger. The amount of anisometropia had a significant positive correlation with the difference in AL (r = 0.869, P < .001), VCD (r = 0.853, P < .001), and ACD (r = 0.591, P < .001) and a negative correlation with the difference in LT (r = -0.457, P = .009). CONCLUSIONS Ocular biometrics differ in many aspects between the fellow eyes of anisometropic Chinese children, and the difference is correlated with the degree of anisometropia.

Spaceflight is known to cause ophthalmic changes in a condition known as spaceflight-associated neuro-ocular syndrome (SANS). It is hypothesized that SANS is caused by cephalad fluid shifts and potentially mild elevation of intracranial pressure (ICP) in microgravity. Head-down tilt (HDT) studies are a ground-based spaceflight analogue to create cephalad fluid shifts. Here, we developed non-invasive magnetic resonance imaging (MRI)-based techniques to quantify ophthalmic structural changes under acute 15° HDT. We specifically quantified: (i) change in optic nerve sheath (ONS) and optic nerve (ON) cross-sectional area, (ii) change in ON deviation, an indicator of ON tortuosity, (iii) change in vitreous chamber depth, and (iv) an estimated ONS Young's modulus. Under acute HDT, ONS cross-sectional area increased by 4.04 mm 2 (95% CI 2.88–5.21 mm 2 , p < 0. 000), while ON cross-sectional area remained nearly unchanged (95% CI −0.12 to 0.43 mm 2 , p = 0.271). ON deviation increased under HDT by 0.20 mm (95% CI 0.08–0.33 mm, p = 0.002). Vitreous chamber depth decreased under HDT by −0.11 mm (95% CI −0.21 to −0.03 mm, p = 0.009). ONS Young's modulus was estimated to be 85.0 kPa. We observed a significant effect of sex and BMI on ONS parameters, of interest since they are known risk factors for idiopathic intracranial hypertension. The tools developed herein will be useful for future analyses of ON changes in various conditions.

Purpose. To assess the visual and refractive outcome of immediate intraoperative vitrectomy and intrascleral intraocular lens implantation using a “standardized” sutureless Yamane technique during cataract luxation in the vitreous chamber as a complication of phacoemulsification. Design. A prospective, interventional, consecutive case series. Materials and Methods. Twelve patients underwent vitrectomy and intrascleral intraocular lens fixation using a standardized Yamane technique as the primary procedure during complicated phacoemulsification. Patients were evaluated preoperatively and 6 months postoperatively for best-corrected distance visual acuity, correspondence to the preoperative refractive target in the spherical equivalent, endothelial cell count, and complications. Results. Mean preoperative best-corrected visual acuity was 1.16 ± 0.3 logarithm of the minimum angle of resolution (logMAR), the endothelial cell count was 1910.5 ± 297.64, and target refraction at baseline was −0.197 ± 0.087. Postoperatively, best-corrected visual acuity was significantly improved; the mean value was 0.05 logMAR ± 0.06. Mean baseline target refraction in the spherical equivalent was −0.20 ± −0.09 (range: −0.08 to −0.37), and mean final refraction was −0.44 ± −0.14 (range: −0.25 to −0.75) with no significant difference p = 0.87 . No complication was registered intra- and postoperatively. Conclusion. Standardization of the Yamane technique seemed a valuable option for patients who had complicated phacoemulsification to achieve a predictable refractive outcome. Synopsis. The predictable refractive outcome could be achieved with the immediate standardized Yamane technique in patients with intraoperative cataract luxation in the vitreous chamber during phacoemulsification.

Clinical relevance: Ocular biometry is key to understanding the determinants of ocular development and pathology changes, especially for the thriving myopic population in Asia. Investigating biometric data in highly myopic eyes within a wide age spectrum is therefore of high importance.Background: To report the magnitude of change in spherical equivalent for each unit of change in the ocular biometry parameters in a highly myopic population in China.Methods: Highly myopic patients aged 7 to 70 years were recruited from the Zhongshan Ophthalmic Center, China. Each patient had a cycloplegic refraction and a measurement of ocular biometry.Results: Data from 823 right eyes were available for analysis, with a mean age of 22.7 years and a median spherical equivalent of -8.88 D. Axial length and lens thickness increased with age, while anterior chamber depth (ACD) decreased in older subjects. There was a significant trend of increasing axial length, lens thickness, vitreous chamber depth (VCD) and decreasing ACD and calculated lens power over spherical equivalent quartiles (all p

Purpose: The aim of this study was to estimate and compare the differences in ocular biometric measurements (OBMs), central macular thickness (CMT), and retinal nerve fiber layer thickness (RNFLT) between children with refractive errors and those with emmetropia. Methods: A cross-sectional observational study of 205 children (334 eyes) aged between six and 18 years consisting of four groups (emmetropia, hypermetropia, myopia, and astigmatism) was carried out. Best-corrected visual acuity (BCVA), a detailed ocular examination, OBMs, spectral-domain optical coherence tomography (SD OCT) for RNFLT and CMT in both eyes were evaluated for each child. Results: Mean age of 205 children was 12.4 ± 3.2 years. 55.6% (n = 114) were girls and 44.4% (n = 91) were boys. There was a significant difference between the four groups for the parameters spherical equivalent (SE), keratometer readings K1and K2, axial length (AL), anterior chamber depth (ACD), vitreous chamber depth (VCD) and lens thickness (LT) (P < 0.0001). The mean central corneal thickness (CCT) was not significantly different between the four groups (P = 0.076). The mean RNFLT was thinner in the myopic group compared with the emmetropic group (P = 0.0048) There was no significant difference in the mean CMT across the four groups (P = 0.458). Conclusion: The data obtained are helpful in providing the normative as well as a comparative database on OBMs, RNFLT and CMT of the pediatric population. This also facilitates evaluation of RNFLT and CMT measurements in children with amblyopia, optic neuropathies, glaucoma, macular and retinal diseases.

Vision-threatening retinal diseases affect millions of people worldwide, representing an important public health issue (high social cost) for both technologically advanced and new-industrialized countries. Overall RD group comprises the retinitis pigmentosa, the age-related macular degeneration (AMD), the diabetic retinopathy (DR), and idiopathic epiretinal membrane formation. Endocrine, metabolic, and even lifestyles risk factors have been reported for these age-linked conditions that represent a “public priority” also in this COVID-19 emergency. Chronic inflammation and neurodegeneration characterize the disease evolution, with a consistent vitreoretinal interface impairment. As the vitreous chamber is significantly involved, the latest diagnostic technologies of imaging (retina) and biomarker detection (vitreous) have provided a huge input at both medical and surgical levels. Complement activation and immune cell recruitment/infiltration as well as detrimental intra/extracellular deposits occur in association with a reactive gliosis. The cell/tissue aging route shows a specific signal path and biomolecular profile characterized by the increased expression of several glial-derived mediators, including angiogenic/angiostatic, neurogenic, and stress-related factors (oxidative stress metabolites, inflammation, and even amyloid formation). The possibility to access vitreous chamber by collecting vitreous reflux during intravitreal injection or obtaining vitreous biopsy during a vitrectomy represents a step forward for an individualized therapy. As drug response and protein signature appear unique in each single patient, therapies should be individualized. This review addresses the current knowledge about biomarkers and pharmacological targets in these vitreoretinal diseases. As vitreous fluids might reflect the early stages of retinal sufferance and/or late stages of neurodegeneration, the possibility to modulate intravitreal levels of growth factors, in combination to anti-VEGF therapy, would open to a personalized therapy of retinal diseases.

Purpose The aim of this article is to describe an innovative and minimally invasive surgical technique for posterior vitrectomy combined with secondary intraocular lens implantation, using a sutureless scleral fixation Carlevale intraocular lens (I71 FIL SSF Carlevale lens. Soleko IOL Division, Italy). Methods The technique was conducted with only three transconjunctival sclerotomies and a corneal tunnel to perform intraocular lens explantation, posterior vitrectomy and Carlevale intraocular lens implantation. It is easier, quicker, and less invasive than the traditional technique with conjunctival peritomy, two scleral flaps and five sclerotomies. Results Surgery was performed uneventfully on three eyes of three patients. Two of them presented a luxation of the intraocular lens into the vitreous chamber, while one patient presented an intraocular lens subluxation. No complications were observed after a 5 to 8 months of follow-up. The intraocular lenses were well positioned, no conjunctival erosion was noted, and the intraocular pressure remained normal at all stages. Conclusions This is the first report of a combined procedure of IOL explantation, posterior vitrectomy and secondary IOL implantation using only three transconjunctival sclerotomies. This appears to be less invasive and it causes less discomfort to the patient. We suggest considering this technique in all those cases requiring a combined procedure in absence of a proper capsular support.

Vitreous humour is a biologically weak immune cavity of the eye, and is in some way isolated from pathogens of the rest of the organism due to a series of special immunological privileges. However, it is a place where processes of varied ethiology (immune, infectious or neoplastic) can develop indirectly due to leakage or release of molecules or even cells into the vitreous chamber, or may be the receptacle of molecules derived from processes developed in other organs in close contact with the vitreous (such as the retina or other underlying layers such as the choroid), which makes the vitreous body an accessible place for diagnosis and with less potential for side effects for analysis than other adjacent eye structures. This article reviews the most frequent pathologies that requires vitreous diagnosis, the most commonly used approaches for sampling and the diagnostic tests that can be performed on vitreous samples.

Background : Veterinary Ophthalmology provides complementary information for the diagnosis of ocular pathologies. Studies in wild species are essential. Among the diagnostic techniques in ophthalmology, two-dimensional ultrasonography stands out. The agouti is a rodent belonging to the Dasyproctidae family that has been widely used as an experimental model. For these animals, sight is one of the crucial senses for their survival. The aim of this study was to evaluate the effectiveness of the two-dimensional ocular ultrasound technique to obtain anatomical measurements and the external ophthalmic artery resistivity index, presumably normal in the species Dasyprocta prymnolopha . Materials, Methods & Results: Forty eye bulbs of 20 adult rodents of the species were evaluated by ultrasonography. In these animals, B-mode echobiometry was performed using the transpalpebral approach and the hemodynamic study of the external ophthalmic artery using the color Doppler technique. All examinations were initiated by the left eye bulb and all measurements were performed by only one examiner. The collected data related to echobiometry were analyzed using Bioest 5.0 for Windows. Initially, normality was tested using the Shapiro-Wilk test for each parameter, then the paired t -test was performed, comparing right and left eyes, and a significance level of 5% ( P < 0.05) was adopted. Based on the methodology used, the following values were obtained for the right and left eyeballs, respectively: anterior chamber thickness - mean of 1.28 ± 0.3 mm and 1.22 ± 0.1 mm; lens thickness - 8.27 ± 0.9 mm and 8.11 ± 0.9 mm; vitreous chamber thickness - 5.35 ± 0.48 mm and 5.30 ± 0.47 mm and axial length - 12.7 ± 0.9 mm and 13 ± 0.68 mm. The mean external ophthalmic artery resistivity values were 0.4305 ± 0.0390 and 0.4258 ± 0.0387 (right and left eye, respectively), characterizing a low resistance. There was no statistical difference between the right and left eyeballs in any of the studied parameters. Discussion : The use of the convex transducer was feasible, promoting adequate contact with the ocular surface and images of satisfactory quality for obtaining measurements, similar to what was observed in studies evaluating the ocular biometry of primates and dogs. The anterior chamber thickness values in this experiment did not differ statistically between the antimers, as well as observed for dogs. The data obtained for lens thickness did not differ statistically for antimers, like those obtained for other rodent species evaluated with the same methodology. The mean values of vitreous chamber thickness were like those observed in chinchillas but correspond to about half of that obtained for capybaras. In this study, the external ophthalmic artery was characterized in all animals, but obtaining the spectral tracing was difficult due to its fine caliber. In wild animals, and especially in wild rodents, there are few data reporting the resistivity of the ophthalmic artery, and there is a lack of studies, which can be explained by the behavioral characteristics of defense and by the high susceptibility to stress in capture, since the performing the technique requires, as in other procedures, the use of chemical containment. Keywords: Doppler flow, ultrasound, eye, agouti.

Background: Ocular biometrics is an easy to perform, safe, non-invasive and low-cost exam that provides immediate results with excellent definition. Brachycephalic dogs have a high risk of developing eye problems, and the early appearance is frequent due to factors linked to anatomical conformation. The aim of the present study was to perform eye biometrics in French Bulldog dogs through ultrasound, correlating with body and head size.Materials, Methods & Results: Clinical examination, ophthalmic examination and ocular biometrics were performed using B-mode ultrasonography, using a 10 megahertz frequency transducer in 30 French Bulldog dogs, aged 1-6 years old, male and females from the Br Lord's Staff kennel and the Radiovet - Rio de Janeiro veterinary clinic. A drop of anesthetic eye drops containing 1% tetracaine hydrochloride and 0.1% phenylephrine hydrochloride was instilled and the direct contact technique was performed with the cornea with the help of sterile water-soluble lubricating acoustic gel between the transducer and the examined eye. These measurements were correlated with cephalic measurements (frontal-occipital distance, skull circumference, distance between the zygomatic arches and frontal-nasal distance) and with body measurements (length of the dog from the cranial end of the sternum to the ischial tuberosity and height of the withers from the cranial angle of the scapula to the ground). No chemical restraint was necessary. Dogs were positioned seated or in sternal decubitus, with slight physical restraint. All measurements were performed by the same examiner. There was no significant difference between the parameters of male and female eye biometrics and there was no difference between the measurements of the right and left eyes. The mean value of axial bulb length was 19.51 ± 0.58 mm, for the thickness of the lens, 6.71 ± 0.66 mm, for depth of the anterior chamber, 2.36 ± 0.89 mm and for the depth of the vitreous chamber, 10.44 ± 1.32 mm, showing the same pattern as other studies with brachycephalic dogs. The size of the dog or skull did not interfere with the measurements of eye biometrics.Discussion: The French Bulldog breed was selected for this study due to the scarcity of publications on ocular biometrics in brachycephalic breeds.The knowledge of ocular biometrics is extremely important for the understanding and early diagnosis of some anomalies related to the growth of ocular structures. It is an essential method of exploration and diagnosis of diseases of the eye bulb and orbit, being indicated to evaluate variations in size, shape and position of the eye bulb. The casuistry of these dogs with eye diseases in the ophthalmological clinical routine is large, since they have a high risk of developing eye problems. Ultrasonography is an easy to access and safe, non-invasive exam and the direct corneal contact technique allows clearer images. As there was no significant difference in measurements of intraocular structures between the right and left eyes, the normal eye can be a reliable parameter to establish the prosthetic eye bulb for the injured or enucleated eye. In the present study, there were 21 females and 9 males, which may have generated interference in these values since there was no sex ratio. The measurements of axial length, lenticular thickness, depth of the anterior chamber and the vitreous chamber had values similar to other studies with brachycephalic dogs.

A 45-year-old male patient, diagnosed elsewhere as retinal detachment, was seen in the retina services of our institute. There was no history of prior ocular trauma or surgery. His vision was 20/20 in his right eye and 20/125 in the left eye. There were no signs of any ocular inflammation and the

At birth, the eye is moderately hypermetropic but achieves emmetropia by the age of 5–6 years in a large majority (Chakraborty et al., 2020; Gwiazda et al., 1993). The process of emmetropization is attributed to changes in several components of the eye structure, predominantly cornea, crystalline lens and axial length. Emmetropization is possible only when there is a fine balance between the optical power of the eye and its focal length. The former is determined by the combined dioptric power of the cornea and crystalline lens and the latter by the axial length of the eyeball. Increase in axial length has been shown to be the most important factor for reaching emmetropia. The main determinant of this increase is reported to be expansion of the vitreous chamber (Mutti et al., 2005; Larsen, 1971). Growth of the vitreous body during postnatal development is well established. However, what initiates vitreous chamber expansion and what brings about its precise arrest at the point of emmetropization are aspects that have not been explored and remain an enigma. It is hypothesized herein that vitreous chamber expansion and resultant early increase in axial length that precisely stops at the point of emmetropia, occurs secondary to postnatal structural and conformational changes within the vitreous collagen and internal limiting membrane (ILM) collagen and molecular interactions between these two structures.

Myopia is induced when a growing eye wears a diffuser that deprives it of detailed spatial vision (form deprivation, FD). In chickens with optic nerve section (ONS), FD myopia still occurs, suggesting that the signals underlying myopia reside within the eye. As avian eyes differ from mammals, we asked whether local mechanisms also underlie FD myopia in a mammalian model. Young guinea pigs underwent either sham surgery followed by FD (SHAM + FD, n = 7); or ONS followed by FD (ONS + FD, n = 7); or ONS without FD (ONS, n = 9). FD was initiated 3 days after surgery with a diffuser that was worn on the surgically treated eye for 14 days. Animals with ONS + FD developed -8.9 D of relative myopia and elongated by 135 μm more than in their untreated eyes after 2 weeks of FD. These changes were significantly greater than those in SHAM + FD animals (-5.5 D and 40 μm of elongation after 14 days of FD), and reflected exaggerated elongation of the posterior vitreous chamber. The myopia reversed when FD was discontinued, despite ONS, but eyes did not recover back to normal (30 days after surgery, ONS + FD eyes still retained -3 D of relative myopia when SHAM+FD animals had returned to normal). No long-term residual myopia was present after ONS alone, ruling out a surgical artifact. Although the gross mechanism signaling myopic ocular growth and its recovery in the young mammalian eye does not require an intact optic nerve, its fine-tuning is disrupted by ONS.

Purpose is to review the pathogenic mechanism for ocular hypertension and glaucoma development after pars plana vitrectomy. Both acute and chronic causes are considered, and special attention is paid to the theories and clinical evidence on the risk of developing Open Angle Glaucoma (OAG) after Pars Plana Vitrectomy (PPV). Most existing scientific literature on the issue agree on the role of ascorbate as an oxygen scavenger within the vitreous chamber. Oxygen tension in the vitreous and anterior chamber is maximum inn proximity of the retinal surface and endothelium, respectively and steeply decreases toward the lens, on both sides, and trabecular meshwork. Vitreous removal and, to a lesser extent, liquefaction, greatly reduces oxygen tension gradient in vitreous chamber while cataract extraction has similar effects on anterior chamber oxygen gradients. Oxygen derivatives originated from the cornea and retina are actively reduced by the vitreous gel and/or the crystalline lens. Vitreous removal and cataract extraction reduce drastically this function. Most reported clinical series confirm this hypothesis although protocol difference and follow-up length greatly impact the reliability of results.

Made available in DSpace on 2021-06-25T10:35:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-11-15 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) European Regional Development Fund Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Governo Brasil Centro de Instrumentação, Universidade de Coimbra In this paper we study from a mathematical point of view the drug release and the degradation process in the context of biodegradable intravitreal implants. In particular, two different clinical situations are considered: non-vitrectomized and vitrectomized eyes. In the former case we assume that the vitreous humor is replaced by a saline solution or a silicone oil. In intravitreal space, the intravitreal liquid enters the implant by non-Fickian diffusion causing the degradation of the poly(lactic-co-glycolic acid) based implant. Then, drug in the implant dissolves and diffuses out of the polymeric matrix. The transport of drug in the vitreous chamber and retina is modeled by Fickian diffusion and convection generated by the flow of the vitreous humor. In order to numerically solve the system of partial differential equations that define the model, we propose an Implicit–Explicit finite element method that allows for the decoupling of the solution reducing the computational cost of the simulations. Several numerical experiments showing the effectiveness of the proposed numerical schemes are also included. The proposed mathematical model may be useful to optimize patient specific treatments in clinical practice. CMUC Department of Mathematics Universidade de Coimbra Department of Mathematics Universidade Federal do Paraná Vitreoretinal Diseases Unit Universidade Federal de São Paulo Department of Mathematics and Computer Science Universidade Estadual Paulista (Unesp) Faculdade de ciências e tecnologia Pres. Prudente Department of Mathematics and Computer Science Universidade Estadual Paulista (Unesp) Faculdade de ciências e tecnologia Pres. Prudente FAPESP: 2013/07375-0 Governo Brasil: 304256/2017-0 CNPq: 305383/2019-1 Governo Brasil: 408215/2018-6 Centro de Instrumentação, Universidade de Coimbra: UID/MAT/00324/2013

PURPOSE Extensive clinical evidence suggests that time spent outdoors might reduce the risk of myopia. This study aimed to determine whether increasing sunlight exposure has a protective effect on hyperopic-defocus induced myopia in a non-human primate. METHODS Twelve 2-month-old rhesus monkeys were treated monocularly with photorefractive keratectomy (PRK) (4.0 D) and divided randomly into two groups: artificial light (AL; n = 6) and natural light (NL; n = 6). Monkeys in the AL group were reared under artificial (indoor) lighting (08:00-20:00 h). Monkeys in the NL group were exposed to natural (outdoor) lighting for 4 h (09:00-11:00 and 15:00-17:00 h). Ocular refraction, corneal power and axial dimensions were measured before sunlight exposure and every 10 days after PRK. At day 180, retinal histology and apoptosis activity were evaluated by hematoxylin and eosin (H&E) staining and terminal deoxynucleotidyl transferase biotin (dUTP) nick end labelling (TUNEL) assay. RESULTS Mean (±SD) PRK induced anisometropia was +3.11 (0.33) D. At the end of the experiment, both eyes of the NL monkeys exhibited significantly more hyperopia and shorter vitreous chamber depths (VCD), compared with AL monkeys (p

Achromatopsia is an inherited retinal disease characterized by loss of cone photoreceptor function. Day blind CNGA3 mutant Improved Awassi sheep provide a large animal model for achromatopsia. This study measured refractive error and axial length parameters of the eye in this model and evaluated chromatic pupillary light reflex (cPLR) testing as a potential screening test for loss of cone function. Twenty-one CNGA3 mutant, Improved Awassi, 12 control Afec-Assaf and 12 control breed-matched wild-type (WT) Awassi sheep were examined using streak retinoscopy and B-mode ocular ultrasonography. Four CNGA3 mutant and four Afec-Assaf control sheep underwent cPLR testing. Statistical tests showed that day-blind sheep are significantly more myopic than both Afec-Assaf and WT Awassi controls. Day-blind sheep had significantly longer vitreous axial length compared to WT Awassi (1.43 ± 0.13 and 1.23 ± 0.06 cm, respectively, p

Purpose To investigate the distribution of ocular biometric parameters and its association to refraction in university students in central China. Methods Ocular biometric parameters including axial length (AL), central corneal thickness (CCT), keratometry power (K), anterior chamber depth (AQD) and lens thickness (LT) were measured by an optical biometry in a cohort of university students. Corneal radius of curvature (CR), lens position (LP), lens power (PBennett ), vitreous chamber depth (VCD) and AL to corneal radius ratio (AL/CR) were calculated. Cycloplegic refraction was measured using an autorefractor. Results A total of 7650 undergraduate students participated in this study, with a mean age of 20.0 ± 1.4 years. The following ocular biometric parameters were measured: AL (24.78 ± 1.21 mm), CCT (539.83 ± 33.03 μm), AQD (3.23 ± 0.25 mm), LT (3.47 ± 0.18 mm), CR (7.79 ± 0.27 mm), LP (4.97 ± 0.23 mm), VCD (17.55 ± 1.15 mm), PBennett (25.00 ± 1.07 dioptres) and AL/CR (3.18 ± 0.15). Male subjects were found to have longer AL, thicker CCT, flatter CR, thinner lens, deeper AQD and VCD than female ones. Myopic subjects were found to have longer AL, thinner CCT, steeper CR, thinner and posterior lens, deeper AQD and VCD, lower PBennett and larger AL/CR than emmetropes and hyperopes. Spherical equivalent (SE) showed a negative correlation with AL/CR (r = -0.914), AL (r = -0.755) and VCD (r = -0.751). Conclusions This study provided a range of reference values for the main ocular biometric parameters in young adults and reported their distributions based on gender and refractive status. Our study indicates that SE has a strong correlation with AL/CR ratio, AL and VCD.