Ocular Components Research Articles

High-speed OCT-based ocular biometer combined with an air-puff system for determination of induced retraction-free eye dynamics.

We demonstrate a swept source OCT-based ocular biometer integrated with an air-puff stimulus to study the reaction of the eye to mechanical stimulation in vivo. The system enables simultaneous measurement of the stimulus strength and high-speed imaging of the eye dynamics along the visual axis. We characterize the stimulus and perform optimization of the data acquisition for a proper interpretation of the results. Access to the dynamics of axial eye length allows for a determination of the eye retraction, which is used to correct the air-puff induced displacement of ocular structures. We define the parameters to quantify the reaction of the eye to the air puff and determine their reproducibility in a group of healthy subjects. We observe the corneal deformation process and axial wobbling of the crystalline lens. OCT biometer combined with the air puff is the first instrument with the potential to provide comprehensive information on the biomechanics of ocular components.

An In-Depth View of the Porcine Trabecular Meshwork Proteome.

The house swine (Sus scrofa domestica Linnaeus 1758) is an important model organism regarding the study of neurodegenerative diseases, especially ocular neuropathies such as glaucoma. This is due to the high comparability of the porcine and human eye regarding anatomy and molecular features. In the pathogenesis of glaucoma, the trabecular meshwork (TM) forms a key ocular component in terms of intraocular pressure (IOP) elevation. Thereby, functional TM abnormalities are correlated with distinct proteomic alterations. However, a detailed analysis of the TM proteome has not been realized so far. Since the porcine eye has high potential as a model system to study ocular diseases such as glaucoma, the present study focuses on the in-depth analysis of the porcine TM proteome. By use of a bottom-up (BU) mass spectrometric (MS) platform utilizing electrospray ionization liquid chromatography tandem MS (LC-ESI-MS/MS) considering database-dependent and peptide de novo sequencing, more than 3000 TM proteins were documented with high confidence (FDR < 1%). A distinct number of proteins with neuronal association were revealed. To the best to our knowledge, many of these protein species have not been reported for TM tissue before such as reelin, centlein and high abundant neuroblast differentiation-associated protein AHNAK (AHNAK). Thereby, AHNAK might play a superordinate role in the TM regarding proposed tissue involvement in barrier function. Also, a high number of secretory proteins could be identified. The generated TM proteomic landscape underlines a multifunctional character of the TM beyond representing a simple drainage system. Finally, the protein catalogue of the porcine TM provides an in-depth view of the TM molecular landscape and will serve as an important reference map in terms of glaucoma research utilizing porcine animal models, porcine TM tissues and/or cultured TM cells.

Correlation analysis and multiple regression formulas of refractive errors and ocular components.

The multiple regression formulas and correlation of ocular components with refractive errors are presented by Gaussian optics. The refractive error changing rate for the cornea and lens power, the axial length, anterior chamber depth (ACD) and vitreous chamber depth (VCD) are calculated, including nonlinear terms for more accurate rate functions than the linear theory. Our theory, consistent with the empirical data, shows that the Pearson correlation coefficients for spherical equivalent (SE) and ocular components are highest for SE with axial length, ACD and VCD and weakest for corneal power, lens power and lens thickness. Moreover, our regression formulas show the asymmetric feature of the correlation that the axial length, ACD and VCD are more strongly correlated (with higher negative regression constants) with refractive errors in eyes with hyperopia than in eyes with myopia, particularly for severe hyperopia.

Air-Puff-Induced Dynamics of Ocular Components Measured with Optical Biometry.

To analyze the dynamics of all optical components of the eye and the behavior of the eyeball under air-puff conditions in vivo. To determine the impact of the intraocular pressure (IOP) on the air-puff-induced deformation of the eye. Twenty eyes of 20 healthy subjects were included in this study. The dynamics of the ocular components, such as the cornea, the crystalline lens, and the retina, was measured by a prototype swept source optical coherence tomography biometer integrated with the air-puff system. The system allows to acquire a series of axial scans at the same location as a function of time with no transverse scanning. Several parameters were extracted from optical coherence tomography data. The IOP was measured using a Goldmann applanation tonometry. The measurements of the eyes were performed before and 2 hours after administration of IOP-reducing drops, namely, 0.2 % brimonidine tartrate. There is a statistically significant correlation of corneal thickness, vitreous depth, and eye length with IOP. The deformation amplitudes of the cornea and the crystalline lens are inversely proportional to the IOP, but statistical significance is achieved only for the cornea. The crystalline lens is displaced without compression, and the return has the form of wobbling. The reduction of IOP level induces corresponding changes in the extracted parameters. Optical biometry combined with air puff provides comprehensive information on the in vivo behavior of all ocular components, including the crystalline lens. Measurement of the axial length dynamics of during deformation enables correcting the deformation for eye retraction.

Tear-film-oriented diagnosis for dry eye.

Tear-film (TF) stability protects the ocular surface epithelium from desiccation and is ensured via cooperation between the ocular surface components including constituents of the TF and ocular surface epithelium. Thus, when those components are insufficient or impaired, the TF breakup that initiates dry eye occurs. Recently, new, commercially available eye drops have appeared in Japan that enable TF stabilization via targeted supplementation of deficient ocular surface components. Hence, a new layer-by-layer diagnosis and treatment concept for dry eye, termed tear-film-oriented diagnosis and tear-film-oriented therapy (TFOD and TFOT, respectively), have emerged and become widely accepted in Asian countries and beyond. TFOD is a diagnostic method for dry eye based on the TF dynamics and breakup patterns (BUPs), through which dry-eye subtypes, including aqueous-deficient dry eye, decreased-wettability dry eye, and increased-evaporation dry eye, are diagnosed. BUPs and/or each diagnosed dry-eye subtype can, in a layer-by-layer fashion, reveal the insufficient ocular surface components responsible for the TF breakup. Using these data, the optimal topical TFOT to treat dry eye can be proposed by addressing the TF breakup via the supplementation of the insufficient components. In Japan, TF breakup is now regarded as a visible core mechanism of dry eye, and abnormal breakup time (ie, ≤ 5 seconds) and symptoms are currently considered part of the diagnostic criteria for dry eye. In this review, the importance of TF instability as a core manifestation of dry eye, the molecular mechanism of TF breakup, the concept of TFOD, and the methods for implementing TFOD for TFOT are introduced.

Heredity of interocular similarities in components of refraction: a population-based twin study among 66- to 79-year-old female twins.

To examine genetic influences on interocular similarities in ocular refraction and components of refraction among elderly female twins. Refraction was assessed in 94 monozygotic (MZ) and 74 dizygotic (DZ) female twins aged 66-78years. Absolute values of interocular differences (Aniso variables) in spherical refraction (SR), refractive astigmatism (AST), spherical equivalent (SE), corneal refractive power (CR), corneal astigmatism (CAST), anterior chamber depth (ACD) and axial length (AL) were calculated. The differences between sisters in each of the Aniso variables were calculated and graded into two categories, best differentiating the groups, here isometropic and anisometropic values. The cut-offs for grading as isometropic were AnisoSR<0.75 D, AnisoAST<0.5 D, AnisoSE<1.0 D, AnisoCR<0.5 D, AnisoCAST<0.50 D, AnisoACD<0.1mm and AniosAL<0.1mm. Genetic influences on these traits were investigated by comparing the prevalence of isometropic and anisometropic differences between the MZ and DZ pairs in the Aniso variables and the interrelationships between the Aniso variables. When the Aniso variables were treated as continuous, no significant differences were found between the MZ and DZ subjects. When the proportions of isometropic intratwinpair interocular differences in the Aniso variables in the MZ and DZ cotwins were compared, the prevalences (MZ/DZ) were AnisoSR: 68%/60%; AnisoAST: 66%/57%; AnisoSE: 87%/68%; AnisoCR: 83%/78%; AnisoCAST: 69%/35%; AnisoACD: 77%/63%; and AnisoAL: 76%/60%. The differences were statistically significant for Aniso SE (p=0.035, Fisher's exact test) and CAST (p=0.007). The greater homogeneity in the interocular differences between the MZ sisters supports the assumption that isometropia of different elements of refraction is genetically influenced and tending to continue up to older ages. In cases where AnisoSE was <1.0 D, higher CR in one eye was associated with shorter AL (r=-0.398, p<0.001), thereby contributing to emmetropization, irrespective of zygosity. In the cases of AnisoSE ≥1 D, no similar influence on emmetropization was observed. The difference between sisters in AnisoSE was associated with the intratwinpair difference in Aniso AL, but not with the intratwinpair differences in AnisoCR, irrespective of zygosity. The higher prevalence of similarities in isometropia of the spherical equivalent and corneal astigmatism between the MZ pairs compared to DZ pairs is consistent with the view that genetic influences on the refractive elements of the eye, tending to isometropia, continue into older age. The interrelation between CR and AL tends to maintain isometropia of SE irrespective of zygosity.

Improvement of dose distribution in ocular brachytherapy with 125I seeds 20-mm COMS plaque followed to loading of choroidal tumor by gold nanoparticles.

Brachytherapy using removable ophthalmic plaques loaded with suitable small sealed radioactive seeds adjacent to the ocular's tumor has been widely used as an effective treatment. The aim of this study was to investigate the dose distribution in a modeled eyeball followed to loading of an ocular melanoma tumor with different concentrations of gold nanoparticles (GNPs) as dose enhancement agent by Monte Carlo (MC) calculations. The MC code of MCNPX 2.6.0 was used to modeling of COMS standard eye plaque loaded with 24 125I sources (6711 model) located on the sclera of modeled eyeball with detailed structures and materials. A choroidal melanoma tumor was simulated and loaded with different concentrations of spherical gold GNPs (50 nm in diameter). Dose enhancement factors (DEFs) of ocular components were calculated. The dosimetric properties of 125I source (6711 model) and dose distribution of COMS standard eye plaque were calculated successfully as recommended by TG-43U1; AAPM. Loading of tumor with GNPs increased dose to the tumor and decreased dose to the normal tissues; the DEF was increased up to 2.280 and 2.030 for tumor apex, while it was decreased to 0.760 and 0.892 for macula and for gold-tumor mixture and nanolattice distributions, respectively. Loading the choroidal tumor volume with GNPs improves the dose distribution by increasing dose to the tumor and decreasing dose to the health components in ocular brachytherapy with 125I seeds 20-mm COMS plaque.

Color and Temporal Frequency Sensitive Eye Growth in Chick.

PurposeLongitudinal chromatic aberration can provide luminance and chromatic signals for emmetropization. A previous experiment examined the role of temporal sensitivity to luminance flicker in the emmetropization response. In the current experiment, we investigate the role of temporal sensitivity to color flicker.MethodsFive-day-old chicks were exposed to sinusoidal color modulation of blue/yellow (N = 73) or red/green LEDs (N = 84) at 80% contrast for 3 days. The modulation frequencies used were as follows: 0, 0.2, 1, 2, 5, and 10 Hz. There were 5 to 16 chicks per condition. Mean illumination was 680 lux. Changes in ocular components were measured using Lenstar, and refraction was measured with a Hartinger refractometer.ResultsEyes grew less when exposed to high temporal frequencies and more at low temporal frequencies. With blue/yellow modulation, the temporal variation was small; eyes grew 268 ± 15 μm at 0 Hz and 224 ± 12 μm at 10 Hz, representing a 16.4% growth reduction. With red/green modulation, eyes grew 336 ± 31 μm at 0 Hz and 218 ± 20 μm at 10 Hz, representing a 35% growth reduction. Choroidal and anterior chamber changes compensated for eye growth, reducing refractive effects; blue/yellow refraction changes ranged from −0.63 to 1.04 diopters.ConclusionsAt high temporal frequencies, color is not a factor, but at low temporal frequencies, red/green modulation produced maximal growth. The pattern of changes observed in each ocular component with changes in the temporal frequency and/or the color of the stimulus was consistent with the idea that the natural sunlight spectrum may be optimal for emmetropization.

Photoacoustic Ophthalmoscopy: Principle, Application, and Future Directions.

Photoacoustic ophthalmoscopy (PAOM) is a novel, hybrid, non-ionizing, and non-invasive imaging technology that has been used to assess the retina. PAOM can provide both anatomic and functional retinal characterizations with high resolution, high sensitivity, high contrast, and a high depth of penetration. Thus, ocular diseases can be precisely detected and visualized at earlier stages, resulting in an improved understanding of pathophysiology, improved management, and the improved monitoring of retinal treatment to prevent vision loss. To better visualize ocular components such as retinal vessels, choroidal vessels, choroidal neovascularization, retinal neovascularization, and the retinal pigment epithelium, an advanced multimodal ocular imaging platform has been developed by a combination of PAOM with other optical imaging techniques such as optical coherence tomography (OCT), scanning laser ophthalmoscopy (SLO), and fluorescence microscopy. The multimodal images can be acquired from a single imaging system and co-registered on the same image plane, enabling an improved evaluation of disease. In this review, the potential application of photoacoustic ophthalmoscopy in both research and clinical diagnosis are discussed as a medical screening technique for the visualization of various ocular diseases. The basic principle and requirements of photoacoustic ocular imaging are introduced. Then, various photoacoustic microscopy imaging systems of the retina in animals are presented. Finally, the future development of PAOM and multimodal imaging is discussed.

Four-year change in ocular biometric components and refraction in schoolchildren: A cohort study

PurposeTo determine 4-year changes of ocular biometric and dioptric components in Iranian children aged 7–11 years following the first phase. Methods468 children were evaluated in the first phase of the study in 2012 and again in 2016–2017. Multi-stage stratified cluster sampling was applied to select the participants. The Topcon autorefractometer and the LENSTAR/BioGraph biometer (WaveLight AG, Erlangen, Germany) were used for cycloplegic refraction and biometry, respectively. All measurements were repeated at 4 years as the baseline assessments. ResultsOf 468 children, 251 (53.6%) were boys. Spherical equivalent (SE) showed a marked myopic shift (P = 0.000) in the second phase which was significantly higher in boys (0.24 vs. 0.18 D) (P < 0.001). Axial length (AL) and anterior chamber depth (ACD) increased by 0.49 ± 0.05 and 0.12 ± 0.02 mm, while lens thickness (LT) and lens power (LP) decreased by 0.08 ± 0.01 mm and 1.59 ± 0.12 D, respectively (P < 0.05). The mean corneal curvature and thickness did not change significantly during 4 years. All biometric component changes were greater in boys. Biometric changes in different age groups showed a decreased LP, increased AL, and increased ACD in most age groups (P < 0.05), while LT and SE did not change significantly in the age groups 9 and 11 years and 8 and 9 years, respectively. Changes in the corneal thickness, diameter, curvature, and refractive astigmatism were not significant in any of the age groups (P > 0.05). ConclusionsStatistical and clinical changes were seen in AL, ACD, LP, and LT. The changes observed in biometric components (AL, ACD, and LT) had a sinus rhythm.

Hand hygiene is linked to microbial keratitis and corneal inflammatory events.

Lack of or inadequate hand washing is a risk factor in the development of contact lens related microbial keratitis and corneal inflammatory events. In the public health domain there is compelling evidence that proper hand washing with soap can save lives. The purpose of this review is to draw attention to some of the public health literature in support of hand washing and how education can influence patients' hand hygiene behavior. Contact lens wearers are also guilty of poor hand washing behavior but there is scant evidence that education of hand washing procedures of lens wearers alters patient non-compliance. It is well known that pathogenic microbial contamination of contact lenses, lens cases, care solutions and anterior ocular components have been found with contact lens wear. However while the originating source may be hands or water, it is most likely both of these. Besides proper hand washing this paper will include mitigating strategies for avoiding microbial contamination.

Ocular Component Development during Infancy and Early Childhood.

The study fills an important gap by providing a longitudinal description of development of the major structural and optical components of the human eye from 3 months to nearly 7 years of age. Normative development data may provide insights into mechanisms for emmetropization and guidance on intraocular lens power calculation. The purpose of this study was to describe the pattern of development of refractive error and the ocular components from infancy through early childhood. Cycloplegic retinoscopy (cyclopentolate 1%), keratophakometry, and ultrasonography were performed longitudinally on between 162 and 293 normal birth weight infants at 0.25, 0.75, 1.5, 3, 4.5, and 6.5 years of age. Refractive error and most ocular components displayed an early exponential phase of rapid development during the first 1 to 2 years of life followed by a slower quadratic phase. Anterior and vitreous chamber depths, axial length, and crystalline lens radii increased at every visit. The crystalline lens thinned throughout the ages studied. The power of the cornea showed an early decrease, then stabilized, whereas the crystalline lens showed more robust decreases in power. The crystalline lens refractive index followed a polynomial growth and decay model, with an early increase followed by a decrease starting at 1 to 2 years of age. Refractive error became less hyperopic and then was relatively stable after 1 to 2 years of age. Axial lengths increased by 3.35 ± 0.64 mm between ages 0.25 and 6.5 years, showed uniform rates of growth across the range of initial values, and were correlated with initial axial lengths (r = 0.44, P < .001). Early ocular optical and structural development appears to be biphasic, with emmetropization occurring within the first 2 years of infancy during a rapid exponential phase. A more stable refractive error follows during a slower quadratic phase of growth when axial elongation is compensated primarily by changes in crystalline lens power.

Development of Corneal Astigmatism (CA) according to Axial Length/Corneal Radius (AL/CR) Ratio in a One-Year Follow-Up of Children in Beijing, China.

Purpose The correlations between the axial length-to-corneal radius (AL/CR) ratio and corneal astigmatism (CA) were studied by prospectively analyzing and comparing survey data from school children in the Beijing urban area from 2014 to 2015. Methods In this longitudinal study, a total of 2,970 students were enrolled in 2014, and 2,179 students were enrolled in 2015. The students were in grades 1 and 4 of primary schools located in the Yangfangdian district of Beijing. The students were examined using the standard logarithmic visual acuity chart for uncorrected visual acuity (UCVA) and IOLMaster for ocular components. Results From 2014 to 2015, the students from grades 1 and 4 had significantly worse UCVA results, longer axial lengths (AL), and greater AL/CRs (p < 0.001). The boys had a longer AL and corneal radius (CR) than the girls (p < 0.001). A significantly higher rate of increased CA was observed for the students with increased AL/CR than for those with decreased or unchanged ratios (AL/CR for grade 1, X2 = 12.304, p=0.001; for grade 4, X2 = 29.044, p < 0.001). In addition, with increased AL/CR over one year, the CA value of the students in grades 1 and 4 became significantly larger (grade 1, p=0.001; grade 4, p < 0.001); moreover, the UCVA became worse (p < 0.001). Conclusions We found that UCVA and AL growth were affected by aging. An increase in the AL/CR ratio is a risk factor for the progression of corneal astigmatism for school children.

Axial Elongation in Myopic Children and its Association With Myopia Progression in the Correction of Myopia Evaluation Trial

Describe axial elongation using 14-year longitudinal data in a large, ethnically diverse group of myopic children, estimate age and axial length (AL) at stabilization, and evaluate associations between the progression and stabilization of AL and myopia. Axial length was measured by A-scan ultrasonography annually. Axial length data were fit with individual polynomial functions and curve-based parameters (AL at stabilization and age at stabilization when annual rate of axial elongation ≤0.06 mm) were estimated. For myopia progression, noncycloplegic spherical equivalent refractions were fit with Gompertz functions. Four hundred thirty-one participants, with AL and myopia data fit successfully, were classified into four cohorts: Younger (n=30); Older (n=334); AL Stabilized at Baseline (n=19); and AL Not Stabilized (n=48). At AL stabilization, for participants in the Younger and Older Cohorts, mean (SD) age and AL were 16.3 (2.4) years and 25.2 (0.9) mm, respectively. No associations were found between age at AL stabilization and ethnicity, sex, or number of myopic parents. At stabilization, sex and number of myopic parents (both P<0.003), but not ethnicity, were significantly associated with AL. Axial length and myopia progression curves were highly correlated overall (all r>0.77, P<0.0001). However, unlike AL, the amount of myopia did not differ significantly between males and females. In most of the participants, AL increased rapidly at younger ages and then slowed and stabilized. The close association between growth and stabilization of AL and myopia is consistent with the suggestion that axial elongation is the primary ocular component in myopia progression and stabilization.

Prevalence and risk factors of glaucoma in an adult population from Shahroud, Iran

PurposeTo determine the prevalence of glaucoma and its risk factors in a 40- to 64-year-old Iranian population. MethodsIn this cross-sectional study, 6311 individuals between the ages of 40–64 years old in Shahroud, a northeastern city in Iran, were selected through multistage cluster sampling. All participants underwent eye exams, optometry, and imaging. They had stereoscopic optic disc photography, visual field evaluation, and their intraocular pressure (IOP) was measured by ophthalmologists before pupil dilation. Glaucoma was defined by the standardized criteria, offered by the International Society for Geographical and Epidemiological Ophthalmology (ISGEO). ResultsOf the 5190 people who participated in the study (82.2%), data from 4637 people were used in the analysis. The prevalence of glaucoma was 1.92% [95% confidence intervals (CI): 1.53–2.31]; 1.4% (95% CI: 0.96–1.84) in women and 2.62% (95% CI: 1.95–3.28) in men. Glaucoma prevalence was 0.9% in the 40–44 years age group, and significantly increased to 3.55% in the 60–64 years age group. In the multiple logistic regression model, age [odds ratio (OR) = 1.08, 95% CI: 1.05–1.12], IOP (OR = 1.04, 95% CI: 1.01–1.06), axial length (OR = 1.34, 95% CI: 1.1–1.63), corneal radius of curvature (OR = 2.76, 95% CI: 1.26–6.06), and corneal diameter (OR = 0.63, 95% CI: 0.46–0.87) showed significant statistical association with glaucoma. ConclusionsThe prevalence of glaucoma was considerably high at older ages. Major risk factors confirmed by this study included older age and high IOP. Certain ocular biometric components such as the axial length and the corneal radius of curvature must be noted as important glaucoma risk factors at younger ages.

72 - Orbital fat derived mesenchymal stem cells rescue RPE from necrosis and differentiate towards RPE

Purpose: Oxidative stress leads to degeneration of retinal pigment epithelial cells (RPE) in age related macular degeneration. Orbital adipose tissue is of neural crest origin similar to most of the ocular and orbital components including the RPE. Here we isolated a orbital fat derived mesenchymal stem cells (OMSCs), evaluated the protective effect of OMSCs on necrosis of RPE, as well as the potential of OMSCs to differentiate towards RPE.

Deep-PRWIS: Periocular Recognition Without the Iris and Sclera Using Deep Learning Frameworks

This paper is based on a disruptive hypothesis for periocular biometrics—in visible-light data, the recognition performance is optimized when the components inside the ocular globe (the iris and the sclera) are simply discarded, and the recognizer’s response is exclusively based on the information from the surroundings of the eye. As a major novelty, we describe a processing chain based on convolution neural networks (CNNs) that defines the regions-of-interest in the input data that should be privileged in an implicit way, i.e., without masking out any areas in the learning/test samples. By using an ocular segmentation algorithm exclusively in the learning data, we separate the ocular from the periocular parts. Then, we produce a large set of “multi-class” artificial samples, by interchanging the periocular and ocular parts from different subjects. These samples are used for data augmentation purposes and feed the learning phase of the CNN, always considering as label the ID of the periocular part. This way, for every periocular region, the CNN receives multiple samples of different ocular classes, forcing it to conclude that such regions should not be considered in its response. During the test phase, samples are provided without any segmentation mask and the network naturally disregards the ocular components, which contributes for improvements in performance. Our experiments were carried out in full versions of two widely known data sets (UBIRIS.v2 and FRGC) and show that the proposed method consistently advances the state-of-the-art performance in the closed-world setting, reducing the EERs in about 82% (UBIRIS.v2) and 85% (FRGC) and improving the Rank-1 over 41% (UBIRIS.v2) and 12% (FRGC).

EYE HEMODYNAMICS IN YOUNG AND MIDDLE-AGED PATIENTS WITH RETINAL VEIN OCCLUSION

Actuality. Regional hemodynamics сcontravention is one of the key factors in the development of retinal vein occlusion. The available methods estimating the ocular component of oculoorbital blood flow include opthalmoplethysmography and opthalmorheography. The value of opthalmosphygmography is in question due to the dependence of the results obtained from the orbital component of eye hemodynamics. Assessment of the vascular bed in the fluorescein angiography also gives an indirect assessment of ocular blood flow. The objective is to estimate hemodynamics indices and informativity of used methods in young and middle-aged patients with retinal vein occlusion. Materials and methods. The study included 30 patients with retinal vein occlusion. In all patients, routine ophthalmic examination was performed and ocular blood flow was additionally estimated using ophthalmoplethysmography, ophthalmorheography, ophthalmosphygmography, and fluorescein angiography. Results. Insignificant decrease of ocular blood flow indices was found on the eye with RVO in young and middle-aged patients with retinal vein occlusion. High values of factors weight of opthalmoplethysmography and opthalmorheography was found, which were significantly exceed the contribution of ocular pulse amplitude of pressure. Conclusions. There was a tendency to decrease all hemodynamic parameters on the eye with RVO in young and middle-aged patients with retinal vein occlusion. The received high values of factors weights reflect the comparable informativity of opthalmoplethysmography and opthalmorheography. The researchers are more informative, which results were less affected by the blood flow in the orbital tissues.

Prevalence of Congenital Ocular Anomalies among Children with Genetic Disorders: An Egyptian Study

ABSTRACTPurpose: To assess the pattern and frequency of occurrence of ocular anomalies among other genetic disorders in Egypt. Methods: This is a cross-sectional study of 2500 cases presenting with genetic disorders. Cases were recruited from the clinical genetics department of the National Research Centre (NRC) over a four-year period between January 2011 and December 2014. Ophthalmological examination of the cases was performed in the pediatric ophthalmology department of Cairo University Hospitals. Results: Out of 2500 cases with congenital disorders, 2.4% suffered one or more ocular anomalies with a male to female ratio of 1.7:1. Consanguinity was reported in 76.7% and family history was positive in 35% of ocular cases. The most common ocular anomalies were congenital cataract, retinal dystrophies, glaucoma, and retinoblastoma in order of frequency. Chromosomal aberrations were detected in two retinoblastoma cases and in one case of charge association with cataract and iris coloboma. A truncating mutation in exon 8 of OCRL1 was reported in a case of Lowe syndrome with cataract. A total of 51.7% of ocular cases were non-isolated (associated with other genetic disorders). Conclusion: In Egypt, ocular genetic disorders are not uncommon among other genetic disorders. Consanguinity is high, suggesting high incidence of autosomal recessive inheritance of genetic disorders with an ocular component. Proper systemic assessment of all cases with ocular anomalies is a necessity due to the high percentage of non-isolated ocular anomalies. Genetic counseling of parents would help in reducing recurrence rates through prenatal diagnosis whenever possible.

The epidemiology of refraction

SummaryBoth, ophthalmologist and vision researcher are aware that refractive errors are a major risk factor for the development of ocular diseases and therefore, their epidemiology is not only of interest for academia. The refractive state of an eye is determined by the distance between the position of the focal plane and the photoreceptor plane, when accommodation is relaxed. When focal plane and photoreceptor plane coincide, the refractive state is zero, a condition called emmetropia. If refractive errors develop, typical visual functions such as visual acuity or contrast sensitivity are affected, which results in blurry distance vision in the case of myopia. As myopia has become a major concern worldwide due to its increasing prevalence especially in Asian countries and with its known major implications on ocular health that also considerably affect the economy, epidemiological studies are especially focused on the elongation of the eye. This talk will summarize epidemiological findings regarding the development of all the ocular components that influence the refractive state (cornea, crystalline lens, axial length) and geographic (environmental) influences.