Predisposing factors for chronic angle-closure glaucoma

Genetic association of IL1B gene variants with primary glaucoma in a North Indian Punjabi cohort: An original study and meta-analysis

Interleukin (IL) 1B is an important candidate gene in glaucoma pathogenesis as it affects the survival of retinal ganglion cells (RGCs). In the present study, -511T/C and +3953C/T polymorphisms in the IL1B were assessed as genetic risk factors for primary open angle (POAG) and angle closure glaucoma (PACG) in a North Indian Punjabi cohort comprising 867 samples (POAG cases = 307; PACG cases = 133 and controls = 427). Genetic association, diplotype and linkage disequilibrium (LD) analyses were performed. Corrections for confounding variables and multiple testing were applied. An updated meta-analysis was also performed. Pooled OR with 95% CI was calculated for dominant, over dominant, and recessive models. Level of heterozygosity among studies was tested using I2 statistic with fixed or random effect model based on the extent of heterogeneity. For -511T > C polymorphism, a positive association was observed with PACG under dominant (p = 0.038; OR = 0.65; pcorr = 0.011; OR = 0.55) and over dominant models (p = 0.010; OR = 0.59; pcorr = 0.001; OR = 0.46). Significant association of +3953C > T was also observed with POAG under dominant (p = 0.011; OR = 1.46; pcorr = 0.018; OR = 1.48) and PACG under recessive models (p < 0.0001; OR = 4.47; pcorr<0.0001; OR = 4.06). While C-C diplotype provided protection against primary glaucoma (0.67-fold; p = 0.0004), T-T and T-C diplotypes predisposed individuals to higher risk (1.31-fold; p = 0.030 and 1.36-fold; p = 0.022 respectively). In meta-analysis, a significant association between +3453 C>T and POAG was observed under dominant (pooled OR = 1.33, p = 0.0046) and over dominant (pooled OR = 1.25; p = 0.0269) models with overall heterogeneity of 15% and 0% respectively. The study provides strong evidence of IL1B variants in modifying genetic susceptibility to primary glaucoma in the targeted North Indian Punjabi population. Replication of the present findings in other populations, and functional studies are warranted to further assess the relevance of IL1B variants in the pathogenesis of primary glaucoma.

Genetics and Glaucoma: the state of the art

Glaucoma is the second leading cause of irreversible blindness worldwide. Although genetic background contributes differently to rare early-onset glaucoma (before age 40) or common adult-onset glaucoma, it is now considered an important factor in all major forms of the disease. Genetic and genomic studies, including GWAS, are contributing to identifying novel loci associated with glaucoma or to endophenotypes across ancestries to enrich the knowledge about glaucoma genetic susceptibility. Moreover, new high-throughput functional genomics contributes to defining the relevance of genetic results in the biological pathways and processes involved in glaucoma pathogenesis. Such studies are expected to advance significantly our understanding of glaucoma's genetic basis and provide new druggable targets to treat glaucoma. This review gives an overview of the role of genetics in the pathogenesis or risk of glaucoma.

Distribution and Characteristics of Ocular Biometric Parameters among a Chinese Population: A Hospital-Based Study

INTRODUCTION

This study aimed to describe the distribution and characteristics of ocular biometric parameters among a large Chinese population.

METHODS

This retrospective cross-sectional study included 146,748 subjects whose ocular biometric parameters were measured at the ophthalmology clinic of West China Hospital, Sichuan University, and recorded in the hospital database. Ocular biometric parameters, including axial length, anterior chamber depth, corneal keratometry, and keratometric astigmatism, were recorded. Only monocular data for each subject were analyzed to avoid bias.

RESULTS

Valid data from 85,770 subjects (43,552 females and 42,218 males) aged 3-114 years were included in this study. The mean axial length, mean anterior chamber depth, average corneal keratometry, and mean keratometric astigmatism were 24.61 mm, 3.30 mm, 43.76 D, and 1.19 D, respectively. The stratification of the ocular parameters by age and gender showed significant inter-gender and inter-age differences.

CONCLUSIONS

Analysis of a large population of subjects in western China aged 3-114 years showed that the distribution and characteristics of ocular biometric parameters, including axial length, anterior chamber depth, corneal keratometry, and keratometric astigmatism, differed by age and gender. This study is the first to describe ocular biometric parameters in subjects aged > 100 years.

Ocular Biometric Values and Prevalence of Corneal Astigmatism in Patients Candidate for Cataract Surgery

Purpose

To analyze the biometric values and the prevalence of corneal astigmatism in cataract surgery candidates.

Methods

This is a prospective study. Ocular biometric values and corneal keratometric astigmatism were measured by optical low-coherence reflectometry (Lenstar LS 900) before surgery in patients who were candidates for cataract extraction surgery. Descriptive measurements of biometric dimensions and keratometric cylinder data and their correlations with sex and age were evaluated.

Results

Ocular biometric and keratometric values from 2084 eyes of 2084 patients (mean age 66.43, range 19-95 years) were analyzed. The mean values were as follows: corneal astigmatism 0.89 diopter (D), mean corneal keratometry 44.29 D, central corneal thickness 534 μ, internal anterior chamber depth (ACD) 3.11 mm, lens thickness 4.50 mm, and axial length 23.35 mm. Corneal astigmatism was <1.25 D in 1660 (79.5%) of eyes. Astigmatism was with-the-rule in 976 (46.8%) of eyes, against-the-rule (ATR) in 702 (33.7%), and oblique in 406 (19.5%). Analysis of corneal astigmatism revealed a change toward "ATR" with age which was not statistically significant. The ACD was correlated with age. The amount of corneal astigmatism had no correlation with age and sex.

Conclusion

Corneal astigmatism was higher than 1.25 D in about 21% of cataract surgery candidates with slight differences between the various age ranges and had no correlation with age and sex.

Fifteen-Year Incidence Rate of Primary Angle Closure Disease in the Andhra Pradesh Eye Disease Study

PURPOSE

To report on the 15-year incidence of primary angle closure disease (PACD) among participants aged ≥40 years in rural southern India DESIGN: Population-based longitudinal incidence rate study METHODS: Setting: 3 rural study centres.

STUDY POPULATION

Phakic participants aged ≥40 years who participated in both examination time points.

OBSERVATION PROCEDURES

All participants at the baseline and at the mean 15-year follow-up visit underwent a detailed interview, anthropometry, blood pressure measurement, and comprehensive eye examination. Automated perimetry was attempted based on predefined criteria. Main outcome measures included development of any form of PACD, as defined by the International Society for Geographical and Epidemiological Ophthalmology (ISGEO), during the follow-up period in phakic participants, who did not have the disease at baseline.

RESULTS

We analyzed data obtained from 1,197 (81.4% out of available 1,470) participants to calculate the incidence of the disease. The mean age (standard deviation) of the study participants at the baseline was 50.2 (8.1) years, with 670 male (45.5%) and 800 female (54.4%) participants. The incidence rate per 100 person-years (95% confidence interval) for primary angle closure suspect, primary angle closure, and primary angle closure glaucoma was 8.8 (8.4, 9.2), 6.2 (5.9, 6.6), and 1.6 (1.4, 1.8), respectively. Thus, the incidence of all forms of PACD was 16.4 (15.9, 17) per 100 person-years. On logistic regression analysis, female gender was a significant risk factor whereas presence of myopia was protective.

CONCLUSIONS

This study reports long-term incidence of PACD from rural India. It has implications for eye health care policies, strategies, and planning.

Lens extraction for chronic angle-closure glaucoma

BACKGROUND

Primary angle-closure glaucoma (PACG) is characterized by a rise in intraocular pressure (IOP) secondary to aqueous outflow obstruction, with relative pupillary block being the most common underlying mechanism. There is increasing evidence that lens extraction may relieve pupillary block and thereby improve IOP control. As such, comparing the effectiveness of lens extraction against other commonly used treatment modalities can help inform the decision-making process.

OBJECTIVES

To assess the effectiveness of lens extraction compared with other interventions in the treatment of chronic PACG in people without previous acute angle-closure attacks.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, one other database, and two trials registers (December 2019). We also screened the reference lists of included studies and the Science Citation Index database. We had no date or language restrictions.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) comparing lens extraction with other treatment modalities for chronic PACG.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology.

MAIN RESULTS

We identified eight RCTs with 914 eyes. We obtained data for participants meeting our inclusion criteria for these studies (PACG only, no previous acute angle-closure attacks), resulting in 513 eyes included in this review. The participants were recruited from a diverse range of countries. We were unable to conduct meta-analyses due to different follow-up periods and insufficient data. One study compared phacoemulsification with laser peripheral iridotomy (LPI) as standard care. Participants in the phacoemulsification group were less likely to experience progression of visual field loss (odds ratio [OR] 0.35, 95% confidence interval [CI] 0.13 to 0.91; 216 eyes; moderate certainty evidence), and required fewer IOP-lowering medications (mean difference [MD] -0.70, 95% CI -0.89 to -0.51; 263 eyes; moderate certainty evidence) compared with standard care at 12 months. Moderate certainty evidence also suggested that phacoemulsification improved gonioscopic findings at 12 months or later (MD -84.93, 95% CI -131.25 to -38.61; 106 eyes). There was little to no difference in health-related quality of life measures (MD 0.04, 95% CI -0.16 to 0.24; 254 eyes; moderate certainty evidence), and visual acuity (VA) (MD 2.03 ETDRS letter, 95% CI -0.77 to 4.84; 242 eyes) at 12 months, and no observable difference in mean IOP (MD -0.03mmHg, 95% CI -2.34 to 2.32; 257 eyes; moderate certainty evidence) compared to standard care. Irreversible loss of vision was observed in one participant in the phacoemulsification group, and three participants in standard care at 36 months (moderate-certainty evidence). One study (91 eyes) compared phacoemulsification with phaco-viscogonioplasty (phaco-VGP). Low-certainty evidence suggested that fewer IOP-lowering medications were needed at 12 months with phacoemulsification (MD -0.30, 95% CI -0.55 to -0.05). Low-certainty evidence also suggested that phacoemulsification may have improved gonioscopic findings at 12 months or later compared to phaco-VGP (angle grading MD -0.60, 95% CI -0.91 to -0.29; TISA500 MD -0.03, 95% CI -0.06 to -0.01; TISA750 MD -0.03, 95% CI -0.06 to -0.01; 91 eyes). Phacoemulsification may result in little to no difference in best corrected VA at 12 months (MD -0.01 log MAR units, 95% CI -0.10 to 0.08; low certainty evidence), and the evidence is very uncertain about its effect on IOP at 12 months (MD 0.50 mmHg, 95% CI -2.64 to 3.64; very low certainty evidence). Postoperative fibrin reaction was observed in two participants in the phacoemulsification group and four in the phaco-VGP group. Three participants in the phaco-VGP group experienced hyphema. No data were available for progression of visual field loss and quality of life measurements at 12 months. Two studies compared phacoemulsification with phaco-goniosynechialysis (phaco-GSL). Low-certainty evidence suggested that there may be little to no difference in mean IOP at 12 months (MD -0.12 mmHg, 95% CI -4.72 to 4.48; 1 study, 32 eyes) between the interventions. Phacoemulsification did not reduce the number of IOP-lowering medications compared to phaco-GSL at 12 months (MD -0.38, 95% CI -1.23 to 0.47; 1 study, 32 eyes; moderate certainty evidence). Three eyes in the phaco-GSL group developed hyphemas. No data were available at 12 months for progression of visual field loss, gonioscopic findings, visual acuity, and quality of life measures. Three studies compared phacoemulsification with combined phaco-trabeculectomy, but the data were only available for one study (63 eyes). In this study, low-certainty evidence suggested that there was little to no difference between groups in mean change in IOP from baseline (MD -0.60 mmHg, 95% CI -1.99 to 0.79), number of IOP-lowering medications at 12 months (MD 0.00, 95% CI -0.42 to 0.42), and VA measured by the Snellen chart (MD -0.03, 95% CI -0.18 to 0.12). Participants in the phacoemulsification group had fewer complications (risk ratio [RR] 0.59, 95% CI 0.34 to 1.04), and the phaco-trabeculectomy group required more IOP-lowering procedures (RR 5.81, 95% CI 1.41 to 23.88), but the evidence was very uncertain. No data were available for other outcomes.

AUTHORS' CONCLUSIONS

Moderate certainty evidence showed that lens extraction has an advantage over LPI in treating chronic PACG with clear crystalline lenses over three years of follow-up; ultimately, the decision for intervention should be part of a shared decision-making process between the clinician and the patient. For people with chronic PACG and visually significant cataracts, low certainty evidence suggested that combining phacoemulsification with either viscogonioplasty or goniosynechialysis does not confer any additional benefit over phacoemulsification alone. There was insufficient evidence to draw any meaningful conclusions regarding phacoemulsification versus trabeculectomy. Low certainty evidence suggested that combining phacoemulsification with trabeculectomy does not confer any additional benefit over phacoemulsification alone, and may cause more complications instead. These conclusions only apply to short- to medium-term outcomes; studies with longer follow-up periods can help assess whether these effects persist in the long term.

[Acute angle closure : An ophthalmological emergency in the emergency room]

Hintergrund

Die Symptome des akuten Winkelblocks, ein Notfallereignis, das ohne rechtzeitige Therapie zur irreversiblen Erblindung führen kann, sind vielfältig. Diese können initial als internistische oder neurologische Erkrankungen gedeutet werden, wenn Kopfschmerzen, Pupillenstarre oder Übelkeit im Vordergrund stehen. Ziel unserer Studie war es, die Rate belastender und invasiver Diagnostik durch primäre Vorstellung bei Nichtophthalmologen bei akutem primären Winkelblock zu erfassen.

Methode

Retrospektive Single-Center-Studie von Patienten mit akutem primärem Winkelblock. Zur Identifizierung dieser wurden alle Patienten erfasst, bei denen im Universitätsklinikum Freiburg, Klinik für Augenheilkunde im Zeitraum 2014–2018 eine chirurgische Iridektomie (5-133.0) oder Iridotomie durch Laser (5-136.1) durchgeführt wurde. Anschließend erfolgte durch Akteneinsicht die Datenanalyse zur Prüfung der Ein- und Ausschlusskriterien sowie des Krankheitsverlaufs.

Ergebnisse

Eingeschlossen wurden 91 Patienten mit akutem primären Winkelblock. Davon stellten sich 28 % (n = 25) initial bei nichtophthalmologischen Fachdisziplinen vor. In dieser Patientengruppe erhielten 56 % (n = 11) eine nichtzielführende Diagnostik, wobei bei 32 % (n = 8) eine kraniale Bildgebung und bei 8 % (n = 2) eine Lumbalpunktion durchgeführt wurde.

Schlussfolgerung

Bei akutem primären Winkelblock zeigt sich eine hohe Rate an nicht wegweisender Diagnostik durch Nichtophthalmologen, weshalb dieses Krankheitsbild fächerübergreifend präsent sein sollte. Bei unspezifischen Symptomen, wie Kopfschmerzen, Übelkeit und Erbrechen sowie Pupillenstarre, muss an die Möglichkeit eines akuten Augeninnendruckanstiegs durch einen akuten Winkelblock gedacht und das frühzeitige Hinzuziehen eines Ophthalmologen erwogen werden.

Long-Term Substance Use Can Cause Irreversible Photopic Vision Changes in Substance Use Disorder in Remission

OBJECTIVE

Substance use has such effects on pupil diameter. Although there is knowledge about the acute effects of substances on pupils, studies showing their chronic effects are limited. The aim of the present study was to evaluate the effect of long-term substance use on scotopic, mesopic, and photopic vision.

METHODS

The present study with cross-sectional desgn was conducted at the Adiyaman Training and Research Hospital for Psychiatry in Adiyaman. This study involved 110 substance use disorder (SUD) patients and 46 healthy volunteers as the control. The parameters were measured and recorded automatically by a device.

RESULTS

The mean age was 23.44±5.53 years in the SUD group and 24.26±5.38 years in healthy controls (p=0.420). The mean age of onset of the substance was 17.74±3.89 years and the mean duration of substance use was 3.54±2.9 years. It was determined that the patients had not used any substance for a mean of 121.73±117.49 days. There was no significant difference between patient and control groups in terms of scotopic and mesopic measurements of both eyes (p>0.05). Photopic measurements were significantly higher in the patient group than in the control group (p<0.05). Photopic measurements were significantly higher in the opioid, cannabis, ecstasy, and multiple substance use groups than in the control group (p<0.05).

CONCLUSION

The most important topic of this study is that photopic vision is permanently impaired in patients with a history of chronic substance use. This was attributed to disrupted sympathetic-parasympathetic hierarchy.

The Role of Chromosome X in Intraocular Pressure Variation and Sex-Specific Effects

Purpose

The purpose of this study was to identify genetic variants on chromosome X associated with intraocular pressure (IOP) and determine if they possess any sex-specific effects.

Methods

Association analyses were performed across chromosome X using 102,407 participants from the UK Biobank. Replication and validation analyses were conducted in an additional 6599 participants from the EPIC-Norfolk cohort, and an independent 331,682 participants from the UK Biobank.

Results

We identified three loci associated with IOP at genomewide significance (P < 5 × 10-8), located within or near the following genes: MXRA5 (rs2107482, P = 7.1 × 10-11), GPM6B (rs66819623, P = 6.9 × 10-10), NDP, and EFHC2 (rs12558081, P = 4.9 × 10-11). Alleles associated with increased IOP were also associated with increased risk for primary open-angle glaucoma in an independent sample. Finally, our results indicate that chromosome X genetics most likely do not illicit sex-specific effects on IOP.

Conclusions

In this study, we report the results of genomewide levels of association of three loci on chromosome X with IOP, and provide a framework to include chromosome X in large-scale genomewide association analyses for complex phenotypes.

Genetic Basis of Primary Angle Closure Glaucoma: The Role of Collagens and Extracellular Matrix

This is an Editorial and does not have an abstract.

Measurement of Retinal Changes in Primary Acute Angle Closure Glaucoma under Different Durations of Symptoms

Purpose

To investigate the changes of retinal nerve fiber layer (RNFL) in patients after an attack of primary acute angle closure glaucoma (PAACG) and to assess the impact of attack time on prognosis of retinal changes.

Design

cross-sectional study.

Methods

Twenty-six patients with unilateral PAACG attack and cataracts from 2017 to 2019 were enrolled. Eyes with PAACG attack time less than 1 day constituted the group A (n = 13), while eyes with PAACG attack time more than 1 day constituted the group B (n = 13). All patients received phacoemulsification and viscogoniosynechialysis after intraocular pressure (IOP) lowering. All patients underwent ophthalmic examinations including IOP, best-corrected visual acuity (BCVA), and visual field (VF). Optical coherence tomography angiography (OCTA) was used to obtain circumpapillary RNFL vessel density (cpVD). Spectral domain optical coherence tomography (SD-OCT) was used to examine the peripapillary RNFL and macular ganglion cell complex (GCC). All patients accepted 2 assessments before and 1 month after the procedure.

Results

The IOP of all patients recovered to normal (12.77 ± 2.65 mm Hgvs. 12.77 ± 3.85 mmHg, p=0.834) after the procedure. Patients in the group A had better BCVA improvement than those in the group B (1.32 ± 0.84 vs. 0.50 ± 0.21, p=0.004), as well as better mean defect (MD) values from VF (-3.65 ± 2.54 vs -16.05 ± 5.99, p < 0.001). Compared with group B, patients in the group A had thicker macula (Fovea area: 255.00 ± 27.94 μm vs. 203.92 ± 59.73 μm, p=0.010), thicker GCC (82.62 ± 8.76 μm vs. 65.23 ± 18.56 μm, p=0.005), and thicker RNFL (105.08 ± 9.38 μm vs. 77.69 ± 20.23 μm, p < 0.001). Higher blood flow density in all-plexus peripapillary retina was observed in the group A eyes compared with group B (full sector: 0.56 ± 0.02 vs. 0.41 ± 0.07, p < 0.001). In both groups, the association between average RNFL thickness and cpVD as well as MD values and pattern standard deviation (PSD) values from VF was stronger (R ² = 0.58, 0.60, -0.54, respectively, all p < 0.001) than the association between GCC thickness and cpVD, as well as MD values and PSD values (R ² = 0.37, p=0.001; R ² = 0.37, p=0.001; R ² = -0.27, p=0.007).

Conclusion

Patients with attack time less than 1 day had better retinal thickness and all-plexus peripapillary retina blood flow density. Controlling the attack time could decrease retinal damage by PAACG.

COL18A1 is a candidate eye iridocorneal angle-closure gene in humans

Primary angle-closure glaucoma (PACG) is a common form of glaucoma in the Far East. Its defining feature is iridocorneal angle closure. In addition to PACG, indications of angle closure are included in the diagnostic criteria of related conditions primary angle-closure suspect (PACS) and primary angle closure (PAC). To the best of our knowledge, a causative gene for iridocorneal angle closure in humans has not been identified. This study aimed to identify the genetic cause of iridocorneal angle closure in a pedigree with at least 10 individuals diagnosed with PACS, PAC or PACG. Results of linkage analysis, segregation analysis of 44 novel variations, whole exome sequencing of 10 individuals, screenings of controls and bioinformatics predictions identified a mutation in COL18A1 that encodes collagen type XVIII as the most likely cause of angle closure in the pedigree. The role of COL18A1 in the etiology of Knobloch syndrome (KS) that is consistently accompanied by optic anomalies, available functional data on the encoded protein and the recognized role of collagens and the extracellular matrix in glaucoma pathogenesis supported the proposed role of the COL18A1 mutation in the pedigree. Subsequent identification of other COL18A1 mutations in PACS affected individuals of two unrelated families further supported that COL18A1 may affect angle closure. These PACS individuals were parents and grandparents of KS-affected children. In conclusion, a gene that affects angle closure in humans, a critical feature of PACG, has been identified. The findings also reinforce the importance of collagens in eye features and functions.

Effect of age on the morphologies of the human Schlemm's canal and trabecular meshwork measured with swept‑source optical coherence tomography

Purpose

We aimed to measure the sizes of Schlemm’s canal (SC) and the trabecular meshwork (TM) in healthy individuals and to evaluate variations with age from childhood to old age by using swept-source optical coherence tomography (OCT).

Methods

Anterior chamber angle imaging of the superior, inferior, nasal, and temporal regions of the right and left eyes was performed with swept-source OCT. The diameter and area of SC and TM width and thickness were measured manually from OCT images.

Results

A total of 114 healthy individuals were enrolled and included 48 male subjects and 66 female subjects; their ages ranged from 7 to 83 years. Both the SC diameter and area in the four quadrants decreased significantly with aging (P < 0.001) and were wider in the nasal and temporal quadrants compared with the superior and inferior quadrants. Changes in SC size showed significant positive correlations with axial length (AL) and anterior chamber depth (P < 0.001). There was a significant positive association between age and TM thickness in the nasal and temporal quadrants (P < 0.05). The inferior quadrant TM width was the widest among the quadrants. The superior quadrant TM thickness was the thinnest among the quadrants. Changes in TM thickness in the nasal and temporal quadrants showed a significant negative correlation with AL (P < 0.05). There was no statistically significant correlation in SC and TM parameters with central corneal thickness, intraocular pressure, sex, or right or left eye (P > 0.05).

Conclusions

With aging, the SC diameter and area became smaller, TM thickness increased, and TM width seemed to remain constant. Measurements of the sizes of SC and the TM with swept-source OCT could assist in clinical assessments and treatment planning for glaucoma.

Ocular biometric characteristics of cataract patients in western China

BACKGROUND

We aimed to measure ocular biometric characteristics in older cataract patients from western China.

METHODS

Ocular biometry records were retrospectively analyzed for 6933 patients with cataracts (6933 eyes) at least 50 years old who were treated at West China Hospital of Sichuan University.

RESULTS

Partial coherence laser interferometry gave the following population averages: axial length (AL), 24.32 ± 2.42 mm; anterior chamber depth (ACD), 3.08 ± 0.47 mm; keratometric power (K), 44.23 ± 1.66 diopters; and corneal astigmatism (CA), 1.00 ± 0.92 diopters. The percentage of individuals with AL > 26.5 mm was 13.66%, while the percentage with CA > 1.0 diopters was 35.54%. Mean AL and ACD showed a trend of decrease with increasing age (P < 0.001). AL correlated positively with ACD (Spearman coefficient, 0.542) and CA (0.111), but negatively with K (- 0.411) (all P < 0.01). K also correlated negatively with ACD (- 0.078, P < 0.01).

CONCLUSIONS

These results show, for the first time, that older cataract patients from western China have similar ocular biometric characteristics as other populations. The high prevalence of severe axial myopia warrants further investigation.

Evaluation of potential risk factors for development of primary angle-closure glaucoma in Bouviers des Flandres

OBJECTIVE To evaluate potential risk factors for development of primary angle-closure glaucoma (PACG) in Bouviers des Flandres. DESIGN Prospective, observational study. ANIMALS 98 Bouviers des Flandres. PROCEDURES All dogs underwent slit-lamp biomicroscopy, indirect ophthalmoscopy, gonioscopy, applanation tonometry, streak retinoscopy, and A-scan, B-scan, and high-resolution ultrasonography. Iridocorneal angles and degree of pectinate ligament dysplasia sheeting were graded, and an angle index was mathematically derived for each eye on the basis of these values. Ciliary clefts evaluated by high-resolution ultrasonography were classified as open, narrow, or closed. Owners were contacted by telephone 7 to 9 years after the initial examination to determine whether dogs had a subsequent diagnosis of PACG. Relationships between previously recorded variables and the development of PACG were evaluated by logistic regression methods. Available pedigrees were reviewed to assess genetic relationships among affected dogs. RESULTS 9 of 92 (9.8%) dogs with follow-up information available developed PACG. An angle index < 1 and presence of a narrow or closed ciliary cleft in 1 or both eyes were each significantly associated with development of PACG. Odds of developing PACG for dogs with an angle index < 1 (indicating marked reduction in outflow capacity through the iridocorneal angle), a narrow or closed ciliary cleft in > 1 eye, or both findings were 13, 20, and 28 times those for dogs that did not have these findings, respectively. All dogs that developed PACG shared 1 common male sire or grandsire. CONCLUSIONS AND CLINICAL RELEVANCE Several anatomic factors were significant risk factors for development of PACG in this population of dogs. Results also suggested a genetic component for the disease.

Ethnic differences in lens parameters measured by ocular biometry in a cataract surgery population

Purpose

To investigate whether differences exist in lens position and other lens parameters among major ethnic groups with cataractous eyes, which may help explain racial differences in angle closure risk.

Methods

This retrospective, cross-sectional study included 807 adult patients who had cataract surgery between years 2014 and 2016 at the University of California, San Francisco (UCSF). Adult patients of white, Asian, Hispanic and African-American ethnicity were included. Lens position (LP), defined as anterior chamber depth (ACD) + 1/2 lens thickness (LT), was assessed using measurements from optical biometry. Other assessed biometric parameters included axial length (AL), relative lens position (RLP) (defined as LP/AL), and anterior chamber depth (ACD).

Results

A total of 807 patients and 1361 eyes were included in this study from a database of patients having cataract surgery. Mean age was 69.2 years (age range from 18 to 101 years old), and 60.3% of patients were women. The mean LP measurements were 5.54±0.32 mm for white, 5.38±0.32 mm for Asian, 5.32±0.30 mm for Hispanic, and 5.40±0.28 mm for African-American participants. After adjusting for age, sex, and AL, significant differences were found when comparing LP in paired comparisons among White cohort with Asians (P<0.001), Hispanics (P<0.001) and African-Americans (P = 0.003). Additionally, when comparing RLP, similar significant results were found when comparing Whites with Asians (P<0.001), Hispanics (P<0.001) and African-Americans (P = 0.002). Lastly, pair-wise comparison of LT between ethnic groups showed significant differences while comparing Asians with Whites (P = 0.001) and Asians with African-Americans (P<0.001).

Conclusion

The results of this study suggest that the LP of Hispanic, Asian, and African-American patients are significantly smaller than that of White patients, and among all ethnic groups, Hispanics and after Asians have the smallest LP (P<0.001) and RLP (P<0.001). These findings may have implications for the relative risk of angle closure and the potential IOP response after cataract surgery among different ethnic groups.

Limbus-insertion distance of superior rectus in primary angle closure glaucoma: an anterior segment OCT study

OBJECTIVE

To compare the distance from the corneoscleral limbus to the insertion site of the superior rectus of primary angle-closure glaucoma (PACG) patients with normal controls and to identify potential characteristics associated with limbus-insertion distance.

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 92 subjects (eyes) were enrolled in the study: 35 were nonglaucoma controls and 57 were PACG patients.

METHODS

The limbus-insertion distance of the superior rectus was measured by anterior segment optical coherence tomography (AS-OCT) and intraoperative surgical caliper. The anterior chamber parameters were also measured using AS-OCT to identify potential characteristics associated with limbus-insertion distance.

RESULTS

The limbus-insertion distance of the superior rectus was 0.40 ± 0.08 mm shorter in the PACG group than in the normal control group (p < 0.001). Anterior segment parameter values, including anterior chamber depth (ACD), anterior chamber width (ACW), anterior chamber area (ACA), and anterior chamber volume (ACV), were smaller in the PACG group than in the normal control group, but the lens vault was larger (all p < 0.001). A shorter limbus-insertion distance of the superior rectus was significantly associated with shorter axial length and "crowded" angle (smaller ACD, ACW, ACA, and ACV) (all p < 0.05).

CONCLUSIONS

This is the first study to demonstrate that the limbus-insertion distance of the superior rectus was shorter in PACG eyes than in normal eyes. The shorter limbus-insertion distance may be another anatomic characteristic of PACG eyes.

Determination and Validation of Thresholds of Anterior Chamber Parameters by Dedicated Anterior Segment Optical Coherence Tomography

PURPOSE

To determine and validate thresholds of anterior chamber angle (ACA) parameters in discriminating open- vs narrow-angle eyes using images from dedicated anterior segment optical coherence tomography (DASOCT).

DESIGN

Reliability analysis.

METHODS

Eyes imaged by DASOCT and examined with gonioscopy were reviewed. By gonioscopy, eyes were classified as narrow if posterior trabecular meshwork was not visible and open if the angle was open to scleral spur and beyond. Imaging was performed in the dark with the CASIA SS-1000 (Tomey, Nagoya, Japan). ACA parameters angle opening distance (AOD), trabecular-iris space area (TISA), trabecular-iris circumference volume (TICV), length of iridotrabecular contact (ITC), and extent and area of ITC were calculated. AOD, TISA, and TICV were measured at both 500 μm and 750 μm from the scleral spur landmark. Study eyes were randomly divided into training and testing sets. Thresholds were calculated from the training set. Sensitivity, specificity, and agreement were then calculated against the clinical classification using the testing set.

RESULTS

One hundred and eighty-nine eyes (111 open, 78 narrow, including 8 borderline angles) were included. Using the threshold determined in the training set on the testing set, 9 of 24 ACA parameters had no misclassification of narrow-angle eyes as open (sensitivity = 1.0). Of 9 parameters, the specificity was >0.79. The highest kappa values (kappa = 0.91) was AOD750 inferiorly at 0.31 mm threshold, followed by both TICV500 at 1.92 μL and TICV750 at 4.00 μL with kappa = 0.86.

CONCLUSION

The parameters with the best discriminative ability for detecting narrow angles were AOD750 inferiorly, TICV500, and TICV750.

Definition, Classification, and Pathophysiology of Canine Glaucoma

Glaucoma is a common ocular condition in humans and dogs leading to optic nerve degeneration and irreversible blindness. Primary glaucoma is a group of spontaneous heterogeneous diseases. Multiple factors are involved in its pathogenesis and these factors vary across human ethnic groups and canine breeds, so the clinical phenotypes are numerous and their classification can be challenging and remain superficial. Aging and oxidative stress are major triggers for the manifestation of disease. Multiple, intertwined inflammatory and biochemical cascades eventually alter cellular and extracellular physiology in the optic nerve and trabecular meshwork and lead to vision loss.

A Possible Role for LTBP2 in the Etiology of Primary Angle Closure Glaucoma

Purpose:

To assess the association of LTBP2 mutations with primary angle closure glaucoma (PACG).

Methods:

We studied 54 unrelated patients with PACG and one individual with pseudoexfoliation accompanied with angle closure glaucoma; these consisted of 28 female and 27 male subjects aged 27 to 82 (mean, 63) years. The 36 exons and flanking intronic sequences of LTBP2 in all patients were amplified by PCR and sequenced by the Sanger protocol. The sequences were compared to LTBP2 reference sequences. A total of 100 to 400 controls aged at least 60 years old were screened for various variations.

Results:

Out of 24 observed sequence variations, ten were in amino acid coding regions; of these four created synonymous codons while six caused amino acid changes. Based on allele frequencies, biochemical parameters, absence in control individuals, evolutionary conservation of affected amino acids, and bioinformatic predictions on the effects on protein function, it was concluded that only two mutations causing p. Gln1417Arg and p. Gly1660Trp may contribute to PACG. The p. Gly1660Trp mutation was observed in a patient with both PACG and PEX syndrome. P. Gln1417Arg had previously been reported only in a subject with POAG.

Conclusion:

LTBP2 may contribute to PACG. This finding emphasizes that there may be an overlap in the etiology of various forms of glaucoma and the overlaps likely contribute to common features in various forms of glaucoma.

Is being female a risk factor for shallow anterior chamber? The associations between anterior chamber depth and age, sex, and body height

Aim of Study:

To analyze the association between anterior chamber depth (ACD) and age, sex, and body height (BH).

Materials and Methods:

One thousand four hundred eighty eyes of 1480 adults 40 years of age and older receiving preoperative evaluation for cataract surgery were recruited consecutively from June 1, 2006, to December 31, 2010. ACD was measured with the Zeiss IOLMaster. Univariate and multivariate linear regression models were used to analyze the correlations, and receiving operator characteristic (ROC) curves and the area under the curve (AUC) were used for evaluating the predictability of an ACD less than 2.70 mm.

Results:

ACD was negatively correlated with age and positively correlated with BH in both univariate and multivariate regression analysis (P < 0.001). Sex was associated with ACD in univariate analysis, but not after adjustment with age and BH. In predicting an ACD less than 2.70 mm, the AUCs of ROC curves for ‘age and sex’, ‘age and BH’, and ‘age, sex, and BH’ were 0.687, 0.689, and 0.689, respectively.

Conclusion:

Age and BH were independent associating factors of ACD; however, sex was not. Older people and shorter ones likely had shallower ACD, and therefore were predisposed to Primary angle closure glaucoma (PACG). The predictability of ACD by age and BH solely was low, and adding sex did not increase it.

The genetic mechanisms of primary angle closure glaucoma

Primary Angle Closure Glaucoma (PACG) is one of the most common types of glaucoma affecting over 15 million individuals worldwide. Family history and ethnicity are strongly associated with the development of the disease, suggesting that one or more genetic factors contribute to PACG. Although strictly heritable disease-causing mutations have not been identified, a number of recent association studies have pointed out genetic factors that appear to contribute to an individual's risk to develop PACG. In addition, genetic factors have been identified that modify PACG endophenotypes for example, axial length. Herein we review the current literature on this important topic.

Genetic associations in PLEKHA7 and COL11A1 with primary angle closure glaucoma: a meta-analysis

BACKGROUND

Single nucleotide polymorphisms (SNPs) rs11024102 in PLEKHA7 and rs3753841 in COL11A1 were identified to be associated with primary angle closure glaucoma (PACG) by a recent large genome-wide association study. This present study is to evaluate the association of PLEKHA7 rs11024102 and COL11A1 rs3753841 with PACG.

DESIGN

A systematic review and meta-analysis.

PARTICIPANTS

A total of 25 271 subjects (4895 PACG patients and 20 376 controls) in different ethnicities were tested for PLEKHA7 rs11024102 and COL11A1 rs3753841.

METHODS

A comprehensive literature search was conducted on studies published up to July 2014. Summary odds ratios (ORs) and 95% confidence intervals were analysed. Publication bias of the included articles was evaluated using funnel plots and Egger's test.

MAIN OUTCOME MEASURES

OR for the effects of PLEKHA7 rs11024102 and COL11A1 rs3753841 on PACG risk.

RESULTS

Four eligible articles were included in this study for meta-analysis. The overall result showed that SNPs rs11024102 and rs3753841 were statistically associated with PACG (P < 0.001) in fixed-effects model. Stratified analyses showed that the association of PLEKHA7 rs11024102 and COL11A1 rs3753841 with PACG was statistically significant in Asian population (including South Indian cohort) (P < 0.001). In Caucasian population, significant association of COL11A1 rs3753841 with PACG was detected (P = 0.004), but PLEKHA7 rs11024102 did not show any association with PACG (P = 0.140).

CONCLUSIONS

This meta-analysis suggests that PLEKHA7 rs11024102 is associated with PACG in Asian population and COL11A1 rs3753841 has a genetic association with the development of PACG both in Caucasian and Asian populations.

Postiridotomy ultrasound biomicroscopy features in the fellow eye of Chinese patients with acute primary angle-closure and chronic primary angle-closure glaucoma

PURPOSE

To compare the features of postiridotomy ultrasound biomicroscopy (UBM) in Chinese patients with acute primary angle-closure (aPAC) and with chronic primary angle-closure (cPAC) glaucoma.

PATIENTS AND METHODS

Consecutive cases were classified into acute and chronic groups. The acute group included 77 patients with unilateral aPAC. The chronic group included 57 patients with unilateral advanced cPAC glaucoma. In both the groups, the patients' fellow eye underwent a laser iridotomy and was studied. The main outcome measures included qualitative UBM parameters such as a plateau iris, anterior iris insertion, and an anteriorly rotated ciliary process and quantitative UBM parameters such as central anterior chamber depth (ACD), basal iris thickness (IT500), and scleral ciliary process angle (SCPA).

RESULTS

For the qualitative parameters, more eyes in the chronic group had a plateau iris (P=0.046), an anterior iris insertion (P=0.222), and an anteriorly rotated ciliary process (P=0.090) than those in the acute group. For the quantitative parameters, the eyes in the chronic group had a deeper ACD (P<0.001), thicker IT500 (P<0.001), and smaller SCPA (P<0.001) than those in the acute group.

CONCLUSIONS

The UBM features of Chinese patients with cPAC include a more plateaued iris, a thicker basal iris, and a smaller SCPA, whereas patients with aPAC may have a shallower ACD. For Chinese patients, a nonpupillary block component may play a more important role in asymptomatic cPAC than in aPAC.

A Study on the Central Corneal Thickness of Primary Angle Closure and Primary Angle Closure Glaucoma and Its Effect on Visual Field Progression

PURPOSE

To determine the mean central corneal thickness (CCT) and the relationship between the CCT and visual field progression in primary angle closure (PAC) and primary angle closure glaucoma (PACG).

DESIGN

A combined cross-sectional and prospective study on PAC and PACG.

METHODS

A total of 35 eyes were included in the study for each group of normal control, PAC, and PACG patients from eye clinics in Kota Bharu, state of Kelantan, Malaysia, from January 2007 to November 2009. The PAC and PACG patients were divided into thin and thick CCT groups. They were followed up for 12 to 18 months for visual field progression assessment with their mean Advanced Glaucoma Intervention Study (AGIS) score.

RESULTS

The CCT was 516.8 ± 26.0 µm for PAC and 509.7 ± 27.4 µm for PACG. Both were significantly thinner compared with the control group with CCT of 540 ± 27.8 µm (P < 0.001). There was a statistically significant increase in the mean AGIS score after 12.9 ± 1.7 months of follow-up in the thin CCT group for PACG (P = 0.002). However, no significant increase in the mean AGIS score was found for the thick CCT group in PACG and for both thin and thick CCT in PAC.

CONCLUSIONS

The PAC and PACG had statistically significant thinner CCT compared with the controls. Thin CCT was associated with visual field progression based on the mean AGIS score in PACG.

Biometry and corneal astigmatism in cataract surgery candidates from Southern China

PURPOSE

To analyze biometry data and corneal astigmatism in cataract candidates from Southern China.

SETTING

Guangdong Eye Institute, Guangdong General Hospital, Guangzhou, China.

DESIGN

Cross-sectional hospital-based study.

METHODS

The axial length (AL), anterior chamber depth (ACD), horizontal corneal diameter (white to white [WTW]), and corneal power (keratometry [K], flat K, steep K) were measured using the IOLMaster system. Ocular biometric data were collected and analyzed between 2007 and 2011.

RESULTS

The study comprised 6750 eyes of 4561 consecutive cataract candidates with a mean age of 70.4 years ± 10.5 (SD). The mean AL, ACD, and WTW were 24.07 ± 2.14 mm, 3.01 ± 0.57 mm, and 11.68 ± 0.45 mm, respectively. All values were statistically significantly greater in men than in women (P < .001) and had a significant trend toward a decrease as age increased (P < .001). The mean K value was 44.13 ± 1.63 D. The median corneal astigmatism was 0.90 D (interquartile range, 0.54-1.43). Corneal astigmatism of 1.00 D or greater was found in 2963 eyes (43.9%), and 3590 eyes (53.2%) had against-the-rule (ATR) astigmatism. The axis of corneal astigmatism turned in the ATR direction with age.

CONCLUSIONS

This study provides reference data for cataract patients from Southern China. The profiles of ocular biometric data and corneal astigmatism can help improve surgical procedures and intraocular lens design for the Chinese population.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Evaluation of anterior chamber angle under dark and light conditions in angle closure glaucoma: An anterior segment OCT study

AIM

To evaluate changes of nasal and temporal anterior chamber angle (ACA) in subjects with angle closure glaucoma using Spectralis AS-OCT (SAS-OCT) under dark and light conditions.

METHODS

Based on dark-room gonioscopy, 24 subjects with open angles and 86 with narrow angles participated in this study. The nasal and temporal angle opening distance at 500 μm anterior to the scleral spur (AOD500), nasal and temporal ACA were measured using SAS-OCT in light and dark conditions.

RESULT

In 2 groups, ACA and AOD500 in nasal and temporal quadrants were significantly greater in light compared to dark (all with p=0.000). The AOD500 and ACA were significantly higher in nasal than temporal in measured conditions for 2 groups except the ACA and AOD500 of normal group measured in light. The difference between nasal and temporal in dark (29.07 ± 65.71 μm for AOD500 and 5.7 ± 4.07° for ACA) was greater than light (24.86 ± 79.85 μm for AOD500 and 2.09 ± 7.21° for ACA) condition. But the difference was only significant for ACA (p=0.000). The correlation analysis showed a negative correlation between AOD500 and pupil diameter in temporal and nasal quadrants (both with p=0.000). While temporal AOD500 difference correlated with spherical equivalent, temporal and asal gonioscopy, nasal AOD correlated with IOP, temporal and nasal gonioscopy.

CONCLUSIONS

Clinically important changes in ACA structure could be detected with SAS-OCT in nasal and temporal quadrants under different illumination intensity. The results could help in improvement of examination condition for better and more accurate assessment of individuals with angle closure glaucoma.

Comparison of factors associated with occludable angle between american Caucasians and ethnic Chinese

PURPOSE

To determine if factors associated with gonioscopy-determined occludable angle among American Caucasians are similar to those found in ethnic Chinese.

METHODS

This is a prospective cross-sectional study with 120 American Caucasian, 116 American Chinese, and 116 mainland Chinese subjects. All three groups were matched for sex and age (40-80 years). Gonioscopy was performed for each subject (occludable angles = posterior trabecular meshwork not visible for ≥2 quadrants). Anterior segment optical coherence tomography and customized software was used to measure anterior segment biometry and iris parameters, including anterior chamber depth/width (ACD, ACW), lens vault (LV), and iris thickness/area/curvature.

RESULTS

In both Chinese and Caucasians, eyes with occludable angles had smaller ACD and ACW, and larger LV and iris curvature than eyes with open angles (all P < 0.005). Chinese eyes had smaller ACD and ACW than Caucasian eyes (both P < 0.01) in the occludable angle cohort. Iris characteristics did not differ significantly between Chinese and Caucasians in the occludable angle cohort. Based on multivariate logistic regression, gonioscopy-determined occludable angle was significantly associated with LV, iris area, and sex (all P < 0.03) in Chinese; and with LV, ACD, iris thickness, age, and sex (all P < 0.04) in Caucasians.

CONCLUSIONS

Several factors associated with occludable angle differed between Caucasians and Chinese, suggesting potentially different mechanisms in occludable angle development in the two racial groups. This is the first study to demonstrate that lens vault is an important anterior segment optical coherence tomography parameter in the screening for angle closure in Caucasians. In addition, iris thickness was a significant predictor for occludable angles in Caucasians but was not in ethnic Chinese.

Association of genetic variants with primary angle closure glaucoma in two different populations

PURPOSE

A recent large genome-wide association study (GWAS) identified multiple variants associated with primary angle-closure glaucoma (PACG). The present study investigated the role of these variants in two cohorts with PACG recruited from Australia and Nepal.

METHOD

Patients with PACG and appropriate controls were recruited from eye clinics in Australia (n = 232 cases and n = 288 controls) and Nepal (n = 106 cases and 204 controls). Single nucleotide polymorphisms (SNPs) rs3753841 (COL11A1), rs1015213 (located between PCMTD1 and ST18), rs11024102 (PLEKHA7), and rs3788317 (TXNRD2) were selected and genotyped on the Sequenom. Analyses were conducted using PLINK and METAL.

RESULTS

After adjustment for age and sex, SNP rs3753841 was found to be significantly associated with PACG in the Australian cohort (p = 0.017; OR = 1.34). SNPs rs1015213 (p = 0.014; OR 2.35) and rs11024102 (p = 0.039; OR 1.43) were significantly associated with the disease development in the Nepalese cohort. None of these SNPs survived Bonferroni correction (p = 0.05/4 = 0.013). However, in the combined analysis, of both cohorts, rs3753841 and rs1015213 showed significant association with p-values of 0.009 and 0.004, respectively both surviving Bonferroni correction. SNP rs11024102 showed suggestive association with PACG (p-value 0.035) and no association was found with rs3788317.

CONCLUSION

The present results support the initial GWAS findings, and confirm the SNP's contribution to PACG. This is the first study to investigate these loci in both Australian Caucasian and Nepalese populations.

Evaluation of the Van Herick Technique for Screening for Occludable Angles in an African Population

The current gold standard for screening for angle closure and adopting universal approaches to prophylaxis is the assessment of the anterior chamber (AC) angle by gonioscopy, a technique that has substantial interobserver variability and relies on subjective assessment. Slit-lamp estimation of the peripheral anterior chamber depth (ACD) by the Van Herick technique is a noncontact approach for estimating angle width and various authors have commented on its sensitivity and specificity as a screening tool for identifying narrow angles as well as angle closure.This case series draws attention to the fact that as many as 28 out of 36 (77.78%) seemingly open angles on Van Herick test were found to be potentially occludable angles on gonioscopy. Therefore, it may be concluded that gonioscopy is essential even in patients with deep peripheral ACs, before an occludable angle can be ruled out. How to cite this article: Bhartiya S, Shaarawy T. Evaluation of the Van Herick Technique for Screening for Occludable Angles in an African Population. J Current Glau Prac 2013;7(2):88-90.

Genotype-phenotype analysis of SNPs associated with primary angle closure glaucoma (rs1015213, rs3753841 and rs11024102) and ocular biometry in the EPIC-Norfolk Eye Study

AIMS

To investigate if the single nucleotide polymorphisms rs3753841, rs1015213 and rs11024102, recently implicated in the development of acute primary angle closure or primary angle closure glaucoma, are associated with ocular biometric characteristics of British adults in the European Prospective Investigation of Cancer-Norfolk eye study.

METHODS

Genotyping data on rs1015213 (between PCMTD1 and ST18), rs11024102 (at PLEKHA7) and rs3753841 (at COL11A1) were available on 3268 participants. Direct genotypic data was available for rs1015213 and rs3753841. Data was imputed for rs11024102. Ocular biometric data was available on 1137 participants who attended the third European Prospective Investigation of Cancer health examination and 988 (87%) of these participants had no previous cataract surgery either eye. Axial length (AL), anterior chamber depth (ACD) and corneal keratometry were measured by using the Zeiss IOLMaster.

RESULTS

Presence of at least one A allele (AG or AA genotype) for rs1015213 was associated with a shallower ACD (-0.07 mm, 95% CI -0.01 to -0.14 mm, p=0.028) after adjusting for age and sex (both p≤0.001). There was no association with AL or corneal keratometry for rs1015213 genotypes. AL, ACD and keratometry were not associated with rs3753841 or rs11024102 genotypes including after adjusting for age and sex.

CONCLUSIONS

This study suggests that primary angle closure glaucoma susceptibility at the PCMTD1-ST18 locus may be partly explained by an association between rs1015213 and ACD in European populations. This effect is equivalent to almost 20% of the SD of the mean ACD of phakic individuals in this cohort. We were not able to identify any association between rs3753841 or rs11024102 and ocular biometry.

Pupil dynamics in Chinese subjects with angle closure

OBJECTIVE

To evaluate the speed of pupil constriction (SPC) in response to a standardized change in illumination from dark to light using anterior segment optical coherence tomography (AS-OCT) in eyes with closed angles, compared to those with open angles.

METHODS

This was a prospective, comparative, observational study. Study subjects with primary angle-closure glaucoma (PACG) and/or primary angle-closure (PAC) were recruited along with a group of normal as controls. Videos of iris and anterior segment changes in response to illumination were captured with real-time video recording from AS-OCT and analysed frame by frame, beginning from a dilated to a constricted pupil. Customized software was used to measure speed of iris constriction, anterior chamber depth (ACD), anterior chamber width (ACW), iris thickness, and pupil diameter (PD). SPC was defined as the rate of pupil diameter change in response to illumination.

RESULTS

One hundred and sixty three Chinese subjects were recruited in this study. A total of 137 of 163 eligible videos (82.5%) were available for analysis, comprising 87 subjects with closed angles (all had undergone laser peripheral iridotomies before) and 50 with open angles. SPC was less in eyes with closed angles (1.22 mm/sec vs 1.56 mm/sec, p<0.001), after adjusting for age and ACW, and was positively correlated with axial length, ACD, anterior chamber angle status, PD in the dark, and iris thickness in the dark, (all r>0.2, all p<0.05). In multivariate analysis, SPC was independently associated with anterior chamber angle status (closed angle vs open angle) (β=0.276, p=0.016) and PD in dark (β= 0.129, p=0.009), after adjusting for age, ACW, ACD, iris thickness and vertical cup-to-disc ratio.

CONCLUSIONS

Compared to those with open angles, eyes with closed angles in Chinese subjects have slower speed of pupil constriction in response to dark-light change, even after adjusting for biometric factors associated with angle closure. The results suggest that differences in irido-pupillary dynamics may play a role in the pathogenesis of angle closure.

Differences in baseline dark and the dark-to-light changes in anterior chamber angle parameters in whites and ethnic Chinese

PURPOSE

To assess the anterior chamber drainage angle width in the dark and the dark-to-light change (Δ) between Caucasians and Chinese aged 40 years and older.

METHODS

The study groups comprised four age- and sex-matched cohorts: American Caucasians, American Chinese, southern mainland Chinese, and northern mainland Chinese. Anterior segment optical coherence tomography (ASOCT) images of the anterior chamber angles were obtained under both light and dark conditions. The parameters analyzed included angle opening distance (AOD), angle recess area (ARA), and trabecular-iris space area (TISA).

RESULTS

Data were obtained from 121, 124, 121, and 120 participants who were American Caucasians, American Chinese, and southern and northern mainland Chinese, respectively. In a multiple linear regression analysis, adjusted for age, sex, refractive status, pupil size, lens location, and anterior chamber depth (ACD) and width (ACW), the ethnic Chinese had significantly smaller ARAs (regression coefficient, β = -0.06, P < 0.001) and TISAs (β = -0.01, P = 0.039), as well as greater ΔAODs (β = 0.03, P = 0.009) and ΔTISAs (β = 0.02, P = 0.029) than did the Caucasians. For the dark-to-light change analysis, the independent associations between angle width and iris thickness (IT) and iris curvature (ICurv) were identified only in the Chinese.

CONCLUSIONS

Compared with the Caucasians, the ethnic Chinese had smaller ARA and TISA, but greater dark-to-light changes in AOD and TISA, independent of refractive status and overall ocular anterior segment dimensions.

Audiovisual integration in low vision individuals

Behavioral and neurophysiological studies have shown an enhancement of visual perception in crossmodal audiovisual stimulation conditions, both for sensitivity and reaction times, when the stimulation in the two sensory modalities occurs in condition of space and time congruency. The purpose of the present work is to verify whether congruent visual and acoustic stimulations can improve the detection of visual stimuli in people affected by low vision. Participants were asked to detect the presence of a visual stimulus (yes/no task) either presented in isolation (i.e., unimodal visual stimulation) or simultaneously with auditory stimuli, which could be placed in the same spatial position (i.e., crossmodal congruent conditions) or in different spatial positions (i.e., crossmodal incongruent conditions). The results show for the first time audiovisual integration effects in low vision individuals. In particular, it has been observed a significant visual detection benefit in the crossmodal congruent as compared to the unimodal visual condition. This effect is selective for visual stimulation that occurs in the portion of visual field that is impaired, and disappears in the region of space in which vision is spared. Surprisingly, there is a marginal crossmodal benefit when the sound is presented at 16 degrees far from the visual stimulus. The observed crossmodal effect seems to be determined by the contribution of both senses to a model of optimal combination, in which the most reliable provides the highest contribution. These results, indicating a significant beneficial effect of synchronous and spatially congruent sounds in a visual detection task, seem very promising for the development of a rehabilitation approach of low vision diseases based on the principles of multisensory integration.

Sex- and gender-based differences in healthy and diseased eyes

PURPOSE

The aim of this study was to identify sex- and gender-based differences in ocular anatomy, physiology, and disease susceptibility or manifestation.

METHODS

Review of current indexed literature was conducted.

RESULTS

Sex and sex hormones influence the lacrimal system, eyelids and blinking, corneal anatomy and disease, aqueous humor dynamics and glaucoma, crystalline lens and cataract, uveitis and retinal disease, ocular circulation, and optic nerve anatomy and disease. Systemic conditions, particularly autoimmune disease, and conditions that are unique to women, such as pregnancy and menopause, further illustrate the effects of sex hormones on the eye. Gender-based differences in ocular conditions and disease should be considered within the context of the underlying physical and social environment.

CONCLUSIONS

Many sex- and gender-based differences exist in healthy and diseased eyes.