Occludable Angles Research Articles

A Comparative Study of Anterior Segment Optical Coherence Tomography and Gonioscopy in Detection of Narrow, Occludable Angles.

Introduction Glaucoma is a group of progressive optic neuropathies and is a leading cause of blindness. Primary angle-closure glaucoma is a global health problem, and if left untreated, it can lead to irreversible vision loss. Anterior segment imaging with optical coherence tomography (AS-OCT) is a rapidly advancing field in ophthalmology. Early detection of narrow, occludable angles using AS-OCT can lead to early and prompt management, resulting in the preservation of vision. Methods We conducted a cross-sectional, outpatient department (OPD)-based study of 212 eyes of patients. Eyes with narrow angles were selected for this study. Eyes identified as having narrow angles on Van Herick (grade ≤2) were confirmed by gonioscopy, and the angles were graded according to the Shaffer gonioscopy grading system. These eyes were further tested using AS-OCT, and the angles, measured in degrees, were graded according to the degrees given in the Shaffer anterior chamber angle grading system. The grades obtained on AS-OCT were compared with those obtained on gonioscopy. The correlation between the narrow angles measured on AS-OCT and those measured on gonioscopy was determined. Results The mean age of the participants was 58.64 years. Of the 212 eyes found to have narrow angles on gonioscopy, 206 eyes (97.2%, 95% CI: 94.0%-99.0%) also had narrow angles on AS-OCT, while six eyes (2.8%, 95% CI: 1.0%-6.1%) were found to have open angles. The chi-square test for association yielded a p-value of <0.001, indicating a statistically significant relationship between AS-OCT and gonioscopy grading. Conclusion This study showed a high correlation between AS-OCT and gonioscopy for grading narrow angles. Gonioscopy remains the gold standard for detecting and managing narrow angles. AS-OCT can be used to identify narrow angles in busy OPDs where these cases can easily be missed. These patients can then be further evaluated with gonioscopy and managed if necessary.

Estimation of angle parameters by ASOCT and biometric parameters by optical biometer in eyes with occludable angles and open angles.

To compare anterior chamber angle (ACA) parameters measured by Anterior Segment Optical Coherence Tomography (ASOCT) and biometric parameters measured by Swept-Source (SS) OCT-based biometry among patients with suspected occludable angles and open angles. An analytical, cross-sectional study was performed on subjects attending our ophthalmology outpatient department with suspected occludable angles (van Herick grades 0, 1, and 2) in group 1, and with open angles (van Herick grades 3 and 4) in group 2. Each subject underwent a complete ophthalmic examination to exclude any intraocular pathology like cataract. We recruited 128 eyes of 64 subjects, 34 in group 1 and 30 in group 2. Each eye was henceforth subjected to ASOCT (Spectralis, Heidelberg Engineering, Heidelberg) and SS-OCT-based optical biometry (IOL Master 700, Carl Zeiss Meditec AG). Anatomical parameters were recorded and compared between the two groups. The main outcome measures of the study included nine ASOCT parameters (central corneal thickness [CCT], lens vault, AOD750, ACA, TISA750 [nasal and temporal], and ACW) and five optical biometric parameters (CCT, ACD, WTW, LT, and axial length). We found a significant difference (p < 0.05) among all the anatomical parameters between the two groups, except CCT which was not significantly different (p = 0.297). ASOCT and SSOCT biometry overcome the challenges of gonioscopy and allow screening for angle closure disease in otherwise normal subjects. ASOCT may serve as an alternative to gonioscopy as it clearly separates occludable angles from open angles in a non-invasive and objective manner.

Nanophthalmos in a case of Alport syndrome: A unique presentation

A 20-year-old male having a positive family history of Alport syndrome presented to us with bilateral sensorineural hearing loss, hematuria, anterior central lenticular opacity in the right eye (RE), and anterior lenticonus in the left eye (LE). The patient had high hyperopia of +10 and +11 Diopter sphere in RE and LE, respectively. The anterior chambers (AC) were shallow (peripheral AC depth, Van Herick grade 1 and 0) with occludable angles on gonioscopy in both eyes (BE), which led us to suspicion of nanophthalmos. The axial length of ~15.35 mm and retinal–choroidal–scleral thickness of ≥2.20 mm in BE, on B scan, confirmed the diagnosis of nanophthalmos. We report this unique case presenting with phenotypes of two genetically diverse disorders, which, to our knowledge, has never been reported before.

Outcomes of newly referred patients with suspected angle closure: do we need to redefine the clinical pathways?

To investigate outcomes of referrals for suspected angle closure and explore whether anterior segment optical coherence tomography (AS-OCT) can be used to tighten triaging criteria in a glaucoma virtual clinic. Retrospectively collected data. The first audit (04/2018-03/2019) identified referrals for suspected angle closure without other glaucoma-related findings (primary angle closure suspect (PACS) referrals). All patients underwent gonioscopy. The second audit (04-08/2019) identified patients with suspected angle closure in a virtual clinic. Management outcomes were assessed, using gonioscopy as reference standard. The outcomes of the second audit were re-audited after changing the triaging criterion from angle width <10° to iridotrabecular contact (ITC) in ≥1 quadrants on AS-OCT. Out of 1754 glaucoma referrals (first audit), 24.6% (431/1754) were PACS referrals. Of these, only 10.7% (42/393) had an occludable angle on gonioscopy, with 97.6% (41/42) being PACS. Of these, 78% (32/41) underwent laser peripheral iridotomy. Out of 137 referrals in the virtual clinic (second audit), 66.4% (91/137) were triaged to the face-to-face clinic. Of these, 31.9% (29/91) were discharged. AS-OCT had positive and negative predictive value of 74.3% (95% confidence intervals (CI) 57.8-86.0) and 82.1% (95% CI 70.0-90.2%), respectively, in detecting ITC in ≥1 quadrants. In the re-audit 45.9% (45/98) of those with suspected angle closure were triaged for gonioscopy, with 24.4% (11/45) of them being discharged. PACS referrals represent a substantial burden to hospital-based services and their accuracy is low. ITC in ≥1 quadrants on AS-OCT can be useful in triaging those who need further evaluation with gonioscopy.

Amodal completion of coincidentally occluded angles: a matter of visual approximation

In the Gerbino illusion a regular but coincidentally occluded polygon appears distorted. Such a display represents a critical condition for amodal completion (AC), in which the smooth continuations of contour fragments—however small—conflict with their possible monotonic interpolation. Smoothness and monotonicity are considered the fundamental constraints of AC at the contour level. To account for the Gerbino illusion we contrasted two models derived from alternative AC frameworks: visual interpolation, based on the literal representation of contour fragments, vs. visual approximation, which tolerates a small misorientation of contour fragments, compatible with smoothness and monotonicity constraints. To measure the perceived misorientation of sides of coincidentally occluded angles we introduced a novel technique for analyzing data from a multiple probe adjustment task. An unsupervised cluster analysis of errors in extrapolation and tilt adjustments revealed that the distortion observed in the Gerbino illusion is consistent with visual approximation and, in particular, with the concatenation of misoriented and locally shrinked amodally completed angles. Implications of our technique and obtained results shed new light on visual completion processes.

Bilateral acute angle closure attack precipitated with dengue fever

Dengue is known to cause varied ocular problems from mild-to-severe sight threatening. We present the case of a 63-year-old female patient with bilateral shallow anterior chamber and acute angle closure attack precipitated during the convalescent phase of dengue infection. She arrived at the emergency department at midnight with a history of vomiting, headache, weakness, and pain in the left eye (LE). Her diagnosis of dengue fever was supported by specific serological testing. On ocular examination, the anterior chamber of both eyes was noticeably shallow and her LE felt stony hard on digital palpation. Intravenous mannitol 300 mL over 45 min were given stat followed by topical medications. In the morning, intraocular pressure measured was 10 mmHg (right eye [RE]) and 26 mmHg (LE). After thorough examination, she was diagnosed with occludable angle in RE and angle closure in LE after gonioscopy. Neodymium-doped Yttrium Aluminum Garnet laser peripheral iridotomy was done in both eyes. She was relieved of symptoms. The varied spectrum of possible ocular symptoms should prompt the ophthalmologist to suspect the potential involvement of eye in dengue fever. Detailed history taking is of utmost importance in early diagnosis of some rare presentation of dengue-related ophthalmic involvement. Increased awareness of dengue-related ophthalmic complications among clinicians involved in the care of patients with dengue would facilitate prompt ophthalmologic assessment and emergency medical care.

Outcomes of newly referred patients with suspected angle closure: Do we need to redefine the clinical pathways?

AbstractPurpose: To investigate outcomes of referrals for suspected angle closure and to explore whether anterior segment optical coherence tomography (AS‐OCT) can be used to tighten triaging criteria in a glaucoma virtual clinic.Methods: Retrospectively collected data. The first audit (04/2018–03/2019) identified referrals for suspected angle closure in the absence of other glaucoma‐related findings (primary angle closure suspect (PACS) referrals). All patients underwent gonioscopy. The second audit (04‐08/2019) identified consecutive patients with suspected angle closure in a virtual clinic. Management outcomes were assessed, using gonioscopy as the reference standard. Outcomes were re‐audited after changing the triaging criterion from angle width &lt; 10° to iridotrabecular contact (ITC) in ≥1 quadrants on AS‐OCT.Results: Out of 1754 glaucoma referrals (first audit), 24.6% (431/1754) were PACS referrals. Of these, only 10.7% (42/393) had an occludable angle on gonioscopy, with 97.6% (41/42) being PACS. Of these, 78% (32/41) underwent laser peripheral iridotomy. Out of 137 referrals in the virtual clinic (second audit), 66.4% (91/137) were triaged to the face‐to‐face clinic. Of these, 31.9% (29/91) were discharged. AS‐OCT had positive and negative predictive value of 74.3% (95% confidence intervals (CI) 57.8–86.0) and 82.1% (95% CI 70.0%–90.2%), respectively, in detecting ITC in ≥1 quadrants. In the re‐audit 45.9% (45/98) of those with suspected angle closure were triaged for gonioscopy, with 24.4% (11/45) of them being discharged.Conclusions: PACS referrals represent a substantial burden to hospital‐based services and their ‘accuracy’ appears to be low. ITC in ≥1 quadrants on AS‐OCT can be useful in triaging those who need further evaluation with gonioscopy.

Drug induced secondary angle closure glaucoma- A case series

: We report 3 cases with acute bilateral angle closure glaucoma following intake of oral chlorthalidone, mefenamic acid, topiramate. : Case series. : All patients developed bilateral acute onset painful defective vision with shallow anterior chamber, raised intraocular pressure. Gonioscopy revealed bilateral occludable angle and ultrasonogram B scan showed shallow choroidal detachment, suggestive of drug induced non pupillary block secondary angle closure glaucoma. All patients were managed by discontinuation of causative drug and started on topical antiglaucoma medication and cycloplegic drug. : we would like to bring this potentially sight threatening and reversible ophthalmic condition to general physician, which can be managed effectively by timely referral and intervention.

Apport de la tomographie en cohérence optique dans l’évaluation de l’angle irido-cornéen du camerounais

Our work was aimed at determining the sensitivity and specificity of anterior segment OCT (AS-OCT) in the evaluation of the iridocorneal angle (ICA) in Cameroon. We conducted a cross-sectional, analytical study from January 2 to June 30, 2019 in Yaoundé. One hundred and twenty five patients over 35 years of age underwent three-mirror manual glass gonioscopy and AS-OCT. The angle was defined as occludable on manual gonioscopy if the posterior trabecular meshwork, was not visible and on OCT if there was contact between the iris root and the posterior surface of the peripheral cornea. Quantitative parameters (angle opening distance, angle recess area, and trabecular-iris space area) in the nasal and temporal quadrants were recorded for the analysis. Men accounted for 56.20% of the 96 patients selected (192 eyes). The mean age was 54.78±10 years. The prevalence of occludable angles was 18.75% (18/96 patients) and 28.125% (27/96 patients) on manual and automated gonioscopy respectively. Schaeffer-Etienne grades ≤2 were identified in 43/192 (21.94%) nasal quadrants and 33/192 (19.18%) temporal quadrants. The area under the curve (AUC) was maximal for the 500 μm goniometric parameters (> 0.8). An Angle Opening Distance ≤333.50 μm was found in 52/192 nasal quadrants (27.10%) and 53/192 (27.60%) temporal. The sensitivity and specificity of AS-OCT in the detection of occludable angles at 500 μm, were 62.8% and 83.2% respectively in the nasal quadrant, and 66.7% and 80.5% respectively in the temporal quadrant. There was a positive correlation between goniometric parameters on AS-OCT and gonioscopy (P=0.01). Given its higher specificity, AS-OCT should be a supplemental examination in the analysis of an angle which appears closed on manual gonioscopy.

Can ultrasonic biometric indices with optimal cut-offs be a potential screening tool for primary angle closure disease? A case-control study.

Despite a significant disease burden and potential to cause blindness, primary angle closure disease (PACD) does not have a population-based screening programme. Biometric indices using ultrasound A-scan is a potential tool for glaucoma case-detection. Given that genetic and environmental factors influence these parameters and paucity of data on their discrimination thresholds in Indian populace, we conducted a matched case-control study to determine the biometric indices and their discrimination thresholds associated with PACD. We studied 172 eyes of 86 participants (43 cases; 43 controls). We compared the following biometric parameters of cases (PACD, occludable angle ≥180° ± raised intraocular pressure) with age and gender-matched controls (1:1): Anterior chamber depth (ACD), lens thickness (LT), axial length (AXL), lens position (LP), relative lens position (RLP), lens axial factor (LAF), simple crowding value (Cs), ACD/AXL). We performed conditional logistic regression (to identify factors associated with PACD) and Receiver operating characteristic (ROC) analysis (to determine discrimination thresholds). Reduced ACD (Adj OR 0.01; 95% CI: 0.0003-0.15, p < 0.001) and increased LT (Adj OR 10.3; 95% CI:2.42-43.93, p < 0.001) were associated with PACD. On ROC analysis, ACD, Cs, and ACD/AXL had optimum sensitivity/specificity at ≤3.015, ≥0.056 and ≤0.1303, respectively. ACD (88.4%) and Cs (94.2%) had highest sensitivity and specificity, respectively. Ultrasonic biometric parameters differed significantly between PACD and controls. ACD and Cs (at discrimination thresholds of ≤3.015 mm and ≥ 0.056, respectively) using ultrasound A-scan could be a potential tool for PACD case-detection that requires evaluation of its diagnostic yield and cost-effectiveness.

Detection of occludable angle with anterior segment optical coherence tomography and Pentacam as non-contact screening methods

PurposeTo evaluate diagnostic capacity for occludable anterior chamber angle detection with anterior segment optical coherence tomography (AS-OCT) and Pentacam.MethodsObservational cross-sectional study with AS-OCT and Pentacam. AS-OCT measures: angle opening distance from Schwalbe line (SL) perpendicular (AOD-SL-Perp) and vertical to iris (AOD-SL-Vert), and iridotrabecular angle (ITA). Pentacam measures: anterior chamber depth (ACD), anterior chamber volume (ACV), and anterior chamber angle (ACA). We analysed Spearman’s correlation with gonioscopic classification. Area under receiver operating characteristic curves (AUCs) for occludable angle detection were compared. Agreement between iridocorneal values of methods was evaluated.ResultsSeventy-four left eyes of 74 patients. Correlation between temporal AS-OCT and gonioscopy: 0.83 (p < 0.0001) AOD-SL-Perp temporal, 0.82 (p < 0.0001) AOD-SL-Vert temporal, and 0.69 (p < 0.0001) ITA temporal. Correlation between AS-OCT nasal and gonioscopy: 0.74 (p < 0.0001) AOD-SL-Perp nasal, 0.74 (p < 0.0001) AOD-SL-Vert nasal, and 0.70 (p < 0.0001) ITA nasal. Correlation of Pentacam with temporal gonioscopy: 0.57 (p < 0.0001) ACD, 0.56 (p < 0.0001) ACV, and 0.63 (p < 0.0001) ACA. Correlation of Pentacam with nasal gonioscopy: 0.47 (IC 0.27–0.73, p < 0.0001) ACD, 0.49 (p < 0.0001) ACV, and 0.56 (CI 0.38–0.7, p < 0.0001) ACA. AS-OCT AUCs: AOD-SL-Perp temporal 0.89 (CI 0.80–0.95), AOD-SL-Vert 0.87 (CI 0.77–0.94), ITA temporal 0.88 (CI 0.78–0.94), AOD-SL-Perp nasal 0.83 (CI 0.72–0.91), AOD-SL-Vert nasal 0.87 (CI 0.77–0.94), and ITA nasal 0.91 (IC 0.81–0.96). Pentacam AUCs: ACD 0.76 (CI 0.64–0.85), ACV 0.75 (CI 0.63–0.84), and ACA 0.84 (CI 0.74–0.92). No statistical differences between different AUCs. Intraclass correlation coefficient (ICC) of ACA (Pentacam) with ITA temporal (AS-OCT) 0.59 and with nasal ITA nasal (AS-OCT) 0.65.ConclusionBoth systems show high capacity for non-contact occludable angle detection. But agreement between methods is moderate or low.

Changes in Intraocular Pressure (IOP) after Phacoemulsification in Eyes with Occludable Angle Of Anterior Chamber

Changes in Intraocular Pressure (IOP) after Phacoemulsification in Eyes with Occludable Angle Of Anterior Chamber

A genomewide association study on individuals with occludable angles identifies potential risk loci for intraocular pressure

Glaucoma is a heterogeneous group of optic neuropathies and is one of the leading causes of irreversible blindness worldwide. Primary angle closure glaucoma (PACG) is a major subtype, prevalent mostly in east and south Asia, where occludable anterior chamber angle is considered as a primary risk factor, which in turn could be responsible for high intraocular pressure (IOP) and subsequent neurodegeneration of retinal ganglion cells. Clinically, IOP is considered as a major risk factor for glaucoma and viewed as an important endophenotype to promote the disease severity. To investigate the comprehensive genomic insights, we conducted a genomewide association study (GWAS) on IOP in individuals with occludable angle (<15 degrees), thus anatomically predisposed to PACG. After performing GWAS on IOP, we identified 25 genomewide suggestive significant loci (P<1e-05, n = 240) of which, six were in complete linkage disequilibrium with the ABCA4 genic region. We successfully replicated the most significant discovery, SNPs of ABCA4 (rs2065712) in a separate cohort of 89 individuals (P =1.16e-09). We identified multiple SNPs in ABCA4 to be associated with IOP. Also, we obtained genes harbouring significantly associated SNPs, included in relevant biological pathways that could potentially be involved in IOP variation and glaucomatous neurodegeneration.

Loss of Vision after Laser Peripheral Iridotomy: A Case Report

Laser Peripheral Iridotomy (LPI) is a common laser procedure carried out in patients with narrow or occluded irido-corneal angles at risk of developing angle closure glaucoma. Nd-YAG and Argon laser are used sequentially in our local population to create an iridotomy. Posterior segment complications are rare after this procedure and generally can occur due to direct laser induced damage. We report a 44-year old patient, who had LPI performed on his both eyes. Post laser patient complained of reduced vision in his left eye and was evaluated in our glaucoma clinic. On examination, his vision was 20/25 unaided in his right eye and 20/60 in his left eye with no further improvement. Optical coherence tomography (OCT) revealed presence of cystoid macular edema (CME) in his left eye responsible for his reduced vision.&#x0D; Key Words: Laser Peripheral Iridotomy, Cystoid Macular Edema, Argon Laser.

Progression rate to primary angle closure following laser peripheral iridotomy in primary angle-closure suspects: a randomised study.

To report the progression rate (PR) to primary angle closure (PAC) following laser peripheral iridotomy (LPI) in PAC suspects (PACS). Prospective, randomized controlled interventional clinical trial conducted at the Handan Eye Hospital, China. Totally 134 bilateral PACS, defined as non-visibility of the posterior trabecular meshwork for ≥180 degrees on gonioscopy were randomly assigned to undergo LPI in one eye. Gonioscopy and Goldmann applanation tonometry were performed prior to, on day 7 and 12mo post LPI. Eighty of 134 patients (59.7%) could be followed up at one year. The mean intraocular pressure (IOP) in treated eyes was 15.9±2.6 mm Hg at baseline, 15.4±3.0 mm Hg on day 7; 16.5±2.9 mm Hg at one month, and 15.5±2.9 mm Hg at 12mo; the IOP in untreated eyes was similar (P=0.834). One or more quadrants of the angle opened in 93.7% of the LPI treated eyes, but 67.0% (53/79) remained closed in two or more quadrants. The PR to PAC in untreated eyes was 3.75% and one developed acute angle-closure glaucoma (AACG); the PR to PAC in treated eyes was 2.5% and none had developed peripheral anterior synechia (PAS) or AACG. LPI can open some of the occludable angle in the majority of eyes with PACS, but 67% continue to have non-visibility of the trabecular meshwork for over 180 degrees.

English

BACKGROUND Pseudoexfoliation syndrome is the most common identifiable cause of open angle glaucoma worldwide. Pseudoexfoliation glaucoma develops in 50 % of patients with pseudoexfoliation syndrome. The purpose of this study was to assess the clinical profile, intraocular pressure (IOP), gonioscopic findings, disc changes and need for medical or surgical line of management for the control of pseudoexfoliation glaucoma. METHODS It was a prospective hospital based interventional study of 68 consecutive patients diagnosed with pseudoexfoliation glaucoma, who presented to the glaucoma clinic at a tertiary care centre from Nov 2017 to Mar 2019. RESULTS 68 patients diagnosed with pseudoexfoliation glaucoma were evaluated during the study period from November 2017 to March 2019. Male predominance of 43 (63 %) was noticed. Mean age group of study population was 68 years with 44 (65 %) of patients in age group of 61 – 75 years. 55 cases had bilateral pseudoexfoliation. 85 (69 %) eyes had a pressure of &gt; 21 mm of Hg. 97 (79 %) eyes had open angles, 4 (3 %) occludable angles, 22 (18 %) had closed angles. 4 (3 %) of eyes had cup disc ratio &lt; 0.5, 49 (40 %) eyes had cup disc ratio of 0.5 - 0.7, 64 (52 %) had &gt; 0.7 cupping. 38 (31 %) eyes were controlled on medical therapy with topical antiglaucoma medications. In 14 (11 %), eyes were treated with Nd: YAG PI (neodymium-doped yttrium aluminium garnet peripheral laser iridotomy) with medical treatment, 59 (48 %) eyes were taken up for triple procedure. 10 (8 %) eyes could not be controlled using medical therapy and had to be taken for surgical treatment. CONCLUSIONS Pseudoexfoliation glaucoma leads to irreversible visual loss if high IOP is not treated leading to glaucomatous optic nerve damage and visual field loss. The response to medical therapy is poor and needs surgical intervention. KEYWORDS Pseudoexfoliation Glaucoma, Intraocular Pressure, Optic Nerve Damage, Dandruff Like Material

Study of anterior chamber angle: Gonioscopy and ultrasound biomicroscopy

Gonioscopy is the widely used technique of grading and evaluating the anterior chamber angle in current glaucoma evaluation practice. The grading of angle and open angle or narrow angle classification with gonioscopy is fairly accurate when done by an experienced ophthalmologist. In recent years, UBM and anterior segment OCT are advanced and in depth imaging tools for the anterior segment evaluation and accurate angle measurements. In our study, we have included 200 eyes for anterior chamber angle grading with gonioscopy and UBM and results are compared. Our study shows that some amount of estimation of angle depth by gonioscopy is overestimated in nearly closed and grade 1 angles. Estimation of grades 2 and 3 is nearly accurate with gonioscopy and comparable to UBM angle grading. Over diagnosis of occludable angles with gonioscopy which can be explained due to iris contour, inter-observer reliability or limitation to examine far periphery of the angle and this can be overcome by UBM examination. UBM provides accurate anterior chamber angle in degrees, peripheral iris configuration details and quantification of measurements is possible.

The High Prevalence of Narrow Angles and Angle Closure Glaucoma in Eyes with Exfoliation Syndrome

<i>Background</i>: Exfoliation syndrome (ES) is characterised by deposition of flakes of fluffy material over the lens and iris, which is commonly associated with glaucoma, though in majority of the patients it is of open angle type but incidence of angle closure glaucoma is higher than general population. <i>Objective</i>: This study was aimed to establish the real association of narrow angles with exfoliation syndrome by comparing it with age related control group to rule out the confounding factor of increasing age for narrow angles. <i>Patients and methods</i>: This was a prospective study carried out among fifty patients above the age of 50 years, who were suffering from exfoliation syndrome. They were compared with another group of 50, age and sex matched patients without exfoliation. The anterior chamber angle configuration were compared between these two groups. In this study the severity of exfoliation were also studied in relation to narrowness of anterior chamber angle and severity was graded based on the extent of distribution of exfoliation. <i>Results</i>: The study found that there was a high (25%) prevalence of occludable angles (grade I, II) in patients with exfoliation syndrome as compared to control group without exfoliation (10%). Among these eyes with occludable angles, 3.2% had totally occluded angle with angle closure glaucoma. The prevalence of open angle glaucoma was (14.2%) and 3.2% eyes with ES had ocular hypertension. The prevalence of occludable angles increase with severity of exfoliation. <i>Conclusion</i>: So this study concludes that angle closure glaucoma and occludable angles are associated with ES apart from open angle glaucoma. The angle tends to be more occludable as the severity of pseudo exfoliation increases.

How Does Cataract Surgery Rate Affect Angle-closure Prevalence.

A data simulation study suggests that prevalence of occludable angle will decrease when the cataract surgical rate increases in particularly when the surgery focuses on 70+ years old. The purpose of this study was to estimate the effects of cataract surgical rates (CSR) on the prevalence of primary angle-closure glaucoma in the Chinese population. Participants aged 50 years and older from the Liwan Eye Study were included as the study sample. Occludable angle (OA) as a surrogate of primary angle-closure glaucoma was evaluated using static gonioscopy and anterior chamber depth was measured before dilation using A-mode ultrasound. Random sampling was used to generate 50 cohorts with a sample size of 200 for each predefined CSR at 2000, 4000, 6000, 8000, 10,000, 12,000, according to the multinomial distribution. The mean anterior chamber depth and OA rates of each cohort were calculated. Logistic function models of nonlinear least-squares estimation were used to predict the prevalence of OA. Data of the right eye from 1280 participants were included. The prevalence of cataract surgery and OA was 2.27% and 11.3%, respectively. The projected prevalence of OA in the cohorts with CSR of 2000, 4000, 6000, 8000, 10,000 and 12,000 was 11.4% [95% confidence interval (CI), 10.8%-12.0%], 11.2% (95% CI, 10.6%-11.9%), 10.9% (95% CI, 10.3%-11.6%), 11.4% (95% CI, 10.8%-12.1%), 10.8% (95% CI, 10.2-11.4%), and 10.1% (95% CI, 9.46-10.7%), respectively. The OA rates decreased remarkably as CSR increased for those aged 70 years and older. Our study indicated that with CSR increased, the OA prevalence could decrease remarkably especially in the older population. It is advisable to perform cataract surgery at an appropriate time for patients in their late 60s to 70s with significant cataracts.

Non-contact tests for identifying people at risk of primary angle closure glaucoma.

Primary angle closure glaucoma (PACG) accounts for 50% of glaucoma blindness worldwide. More than three-quarters of individuals with PACG reside in Asia. In these populations, PACG often develops insidiously leading to chronically raised intraocular pressure and optic nerve damage, which is often asymptomatic. Non-contact tests to identify people at risk of angle closure are relatively quick and can be carried out by appropriately trained healthcare professionals or technicians as a triage test. If the test is positive, the person will be referred for further specialist assessment. To determine the diagnostic accuracy of non-contact tests (limbal anterior chamber depth (LACD) (van Herick test); oblique flashlight test; scanning peripheral anterior chamber depth analyser (SPAC), Scheimpflug photography; anterior segment optical coherence tomography (AS-OCT), for identifying people with an occludable angle. We searched the following bibliographic databases 3 October 2019: CENTRAL; MEDLINE; Embase; BIOSIS; OpenGrey; ARIF and clinical trials registries. The searches were limited to remove case reports. There were no date or language restrictions in the searches. We included prospective and retrospective cross-sectional, cohort and case-control studies conducted in any setting that evaluated the accuracy of one or more index tests for identifying people with an occludable angle compared to a gonioscopic reference standard. Two review authors independently performed data extraction and quality assessment using QUADAS2 for each study. For each test, 2 x 2 tables were constructed and sensitivity and specificity were calculated. When four or more studies provided data at fixed thresholds for each test, we fitted a bivariate model using the METADAS macro in SAS to calculate pooled point estimates for sensitivity and specificity. For comparisons between index tests and subgroups, we performed a likelihood ratio test comparing the model with and without the covariate. We included 47 studies involving 26,151 participants and analysing data from 23,440. Most studies were conducted in Asia (36, 76.6%). Twenty-seven studies assessed AS-OCT (analysing 15,580 participants), 17 studies LACD (7385 participants), nine studies Scheimpflug photography (1616 participants), six studies SPAC (5239 participants) and five studies evaluated the oblique flashlight test (998 participants). Regarding study quality, 36 of the included studies (76.6%) were judged to have a high risk of bias in at least one domain.The use of a case-control design (13 studies) or inappropriate exclusions (6 studies) raised patient selection concerns in 40.4% of studies and concerns in the index test domain in 59.6% of studies were due to lack of masking or post-hoc determination of optimal thresholds. Among studies that did not use a case-control design, 16 studies (20,599 participants) were conducted in a primary care/community setting and 18 studies (2590 participants) in secondary care settings, of which 15 investigated LACD. Summary estimates were calculated for commonly reported parameters and thresholds for each test; LACD ≤ 25% (16 studies, 7540 eyes): sensitivity 0.83 (95% confidence interval (CI) 0.74, 0.90), specificity 0.88 (95% CI 0.84, 0.92) (moderate-certainty); flashlight (grade1) (5 studies, 1188 eyes): sensitivity 0.51 (95% CI 0.25, 0.76), specificity 0.92 (95% CI 0.70, 0.98) (low-certainty); SPAC (≤ 5 and/or S or P) (4 studies, 4677 eyes): sensitivity 0.83 (95% CI 0.70, 0.91), specificity 0.78 (95% CI 0.70, 0.83) (moderate-certainty); Scheimpflug photography (central ACD) (9 studies, 1698 eyes): sensitivity 0.92 (95% CI 0.84, 0.96), specificity 0.86 (95% CI 0.76, 0.93) (moderate-certainty); AS-OCT (subjective opinion of occludability) (13 studies, 9242 eyes): sensitivity 0.85 (95% CI 0.76, 0.91); specificity 0.71 (95% CI 0.62, 0.78) (moderate-certainty). For comparisons of sensitivity and specificity between index tests we used LACD (≤ 25%) as the reference category. The flashlight test (grade 1 threshold) showed a statistically significant lower sensitivity than LACD (≤ 25%), whereas AS-OCT (subjective judgement) had a statistically significant lower specificity. There were no statistically significant differences for the other index test comparisons. A subgroup analysis was conducted for LACD (≤ 25%), comparing community (7 studies, 14.4% prevalence) vs secondary care (7 studies, 42% prevalence) settings. We found no evidence of a statistically significant difference in test performance according to setting. Performing LACD on 1000 people at risk of angle closure with a prevalence of occludable angles of 10%, LACD would miss about 17 cases out of the 100 with occludable angles and incorrectly classify 108 out of 900 without angle closure. The finding that LACD performed as well as index tests that use sophisticated imaging technologies, confirms the potential for this test for case-detection of occludable angles in high-risk populations. However, methodological issues across studies may have led to our estimates of test accuracy being higher than would be expected in standard clinical practice. There is still a need for high-quality studies to evaluate the performance of non-invasive tests for angle assessment in both community-based and secondary care settings.