Posterior Trabecular Meshwork Research Articles

Comparison of Axial Lengths in Occludable Angle and Angle-Closure Glaucoma—The Bhaktapur Glaucoma Study

To compare the anterior chamber depth (ACD) and axial length of eyes in a population-based sample among normal, occludable angle, and primary angle-closure glaucoma (PACG) groups. Totally, 3979 subjects from a population-based glaucoma prevalence study underwent complete ocular examination including four mirror gonioscopy. An angle in which >270 degrees of the posterior trabecular meshwork could not be seen was considered occludable. PACG was considered when there were features of primary angle closure (eye with an occludable angle, peripheral anterior synechiae, increased intraocular pressure, iris whorling, lens opacities, or excessive pigment deposition on the trabecular surface) and optic disc with glaucomatous damage. A handheld ultrasonic biometer was used to measure the ACD and the axial length of subjects. The ACD and axial length were measured on all subjects with occludable angles (n = 86), PACG (n = 17) and a random subgroup of normal subjects (n = 685). The measurements were compared among the groups and statistically analyzed using independent t-test, one-way analysis of variance, χ2 test, and logistic regression. The mean age among occludable angle and angle-closure glaucoma groups was 59.64 ± 9.70 and 71.23 ± 8.5 years, respectively, which was significantly higher (p < 0.001) than the mean of 54.03 ± 10.90 years among normal subjects. In the occludable angle group, the ACD (2.55 ± 0.69) was significantly different (p < 0.001) than the normal group (2.85 ± 0.39). The axial length (22.08 ± 0.83) in the occludable angle group was also considerably different (p < 0.001) when compared with the normal group (22.62 ± 0.90). In PACG group, the ACD and axial length were 2.48 ± 0.22 and 22.02 ± 0.59, respectively. The risk of having an occludable angle decreased with per unit millimeter increase in ACD (odds ratio, 0.24; 95% confidence intervals, 0.12-0.50) and axial length (odds ratio, 0.49; 95% confidence intervals, 0.36-0.67) after adjusting the effect of age and sex. The eyes in Nepalese population with occludable angle and angle-closure glaucoma appear to have significantly shallower anterior chambers and shorter axial lengths when compared with the normal group.

Glaucoma anterior chamber morphometry based on optical Scheimpflug images

To compare the performance of gonioscopy and noncontact morphometry with anterior chamber tomography (High Resolution Pentacam - HR) using optical Scheimpflug images in the evaluation of the anterior chamber angle (ACA). Transversal study. 112 eyes from 74 subjects evaluated at the Glaucoma Department, Fluminense Federal University, underwent gonioscopy and Pentacam HR. Using gonioscopy, the ACA was graded using the Shaffer Classification (SC) by a single experienced examiner masked to the Pentacam HR findings. Narrow angle was determined in eyes in which the posterior trabecular meshwork could not be seen in two or more quadrants on non-indentation gonioscopy (SC Grade 2 or less). Pentacam HR images of the nasal and temporal quadrants were evaluated by custom software to automatically obtain anterior chamber measurements, such as: anterior chamber angle (ACA), anterior chamber volume (ACV) and anterior chamber depth (ACD). Based on gonioscopy results, 74 (60.07%) eyes of patients classified as open-angle (SC 3 and 4) and 38 (33.93%) eyes of patients classified as narrow-angle (SC 1 and 2). Noncontact morphometry with Scheimpflug images revealed a mean ACA of 39.20 ± 5.31 degrees for open-angle and 21.18 ± 7.98 degrees for narrow-angle. The open-angle group showed significant greater ACV and ACD values when compared to narrow-angle group (ACV of 193 ± 36 mm³ vs. 90 ± 25 mm³, respectively, p<0.001; and ACD of 3,09 ± 0,42 mm vs. 1,55 ± 0,64 mm, respectively, p<0.0001.). In screening eyes with open-angle and narrow-angle with the Pentacam ACA of 20º (SC Grade 2) using the ROC curves, the analysis showed 52.6% of sensitivity and 100% of specificity. The Pentacam showed ability in detecting eyes at risk for angle closure analyzing ACV and ACD.

The Heritability and Sibling Risk of Angle Closure in Asians

To describe the heritability and sibling risk for angle closure. Prospective clinical study. Probands with primary angle closure (PAC) and primary angle-closure glaucoma (PACG) and their first-degree relatives. One hundred probands with PAC and PACG and their first-degree relatives were examined prospectively. All subjects underwent an ophthalmic evaluation that included slit-lamp examination, optic disc evaluation, and gonioscopy. An angle was classified as narrow if the posterior (usually pigmented) trabecular meshwork could be seen for less than 180° of the angle circumference. The heritability of narrow angles was calculated by threshold models. The sibling recurrence and relative risk of having narrow angles compared with the general population was calculated using estimation of sibling genetic risk parameters, corrected for single ascertainment bias. Heritability and sibling risk for narrow angles. One hundred probands (consisting of 76 subjects with PACG and 24 with PAC) were examined together with 327 first-degree relatives. There were 76 female probands and 24 male probands. Of the first-degree relatives, 146 were male and 181 were female. Of the 327 first-degree relatives, 105 (32.1%) had narrow angles. The heritability of narrow angles was 58.8% overall, with the genetic variance being 2.30 and the phenotypic variance being 3.91. Of the 515 sibling pairs examined, 171 (33.1%) pairs had both siblings unaffected, 113 (21.9%) pairs had both siblings affected, 231 (45.0%) pairs had 1 sibling affected. The sibling recurrence risk for having narrow angles was 49% (95% confidence interval, 41.6%-56.8%), whereas the sibling relative risk for narrow angles was 7.57 (95% confidence interval, 6.41-8.74). A high heritability of narrow angles of almost 60% was found. Siblings of Chinese patients with PAC or PACG have almost a 50% probability of having narrow angles and are more than 7 times more likely to have narrow angles than the general population.

Diagnostic Performance of Anterior Chamber Angle Measurements for Detecting Eyes With Narrow Angles

To assess the diagnostic performance of angle measurements from anterior segment optical coherence tomography (AS-OCT) images for identifying eyes with narrow angles. We conducted a community-based cross-sectional study of individuals 50 years or older who had phakic eyes and who underwent AS-OCT imaging in the dark by a single operator and gonioscopy by an ophthalmologist masked to AS-OCT findings. An eye was considered to have narrow angles if the posterior pigmented trabecular meshwork was not visible for at least 180° on gonioscopy. Horizontal AS-OCT images were analyzed for the following measurements using customized software: angle opening distance (AOD) at 250, 500, and 750 μm from the scleral spur; trabecular-iris space area (TISA) at 500 and 750 μm; and angle recess area (ARA) at 750 μm. Areas under the receiver operating characteristic curves (AUCs) were generated for AOD, TISA, and ARA to assess the performance of these measurements in detecting eyes with narrow angles. Of 2047 individuals examined, 582 were excluded mostly because of poor image quality or inability to locate the scleral spur. Of the remaining 1465 participants, 315 (21.5%) had narrow angles on gonioscopy. Mean (SD) age was 62.7 (7.7) years, 54.1% were women, and 90.0% were Chinese. The AUCs were highest for AOD750 in the nasal (0.90 [95% confidence interval, 0.89-0.92]) and temporal (0.91 [0.90-0.93]) quadrants. The AOD750 is the most useful angle measurement for identifying individuals with gonioscopic narrow angles in gradable AS-OCT images. Poor definition of the scleral spur precludes quantitative analysis in approximately 25% of AS-OCT images.

Evaluation of Scanning Protocols for Imaging the Anterior Chamber Angle With Anterior Segment-Optical Coherence Tomography

To evaluate different anterior segment-optical coherence tomography (AS-OCT) scanning protocols for detecting eyes with angle closure. This cross-sectional study enrolled 2104 subjects from a community clinic in Singapore. All participants underwent AS-OCT imaging in the dark (Visante, Carl-Zeiss, Meditec, Dublin, CA), and gonioscopy with a Goldmann 2-mirror and a Sussman lens by an experienced examiner. The anterior chamber angle in a particular quadrant was considered closed on gonioscopy if the posterior trabecular meshwork could not be seen; and on AS-OCT by the presence of contact between the iris and angle wall anterior to the scleral spur. Protocols using combinations of AS-OCT scans of different quadrants of the eye were compared. A total of 1853/2104 right eyes could be graded in all 4 quadrants. In all, 380 (20.5%) eyes had closed angles in at least 2 quadrants on gonioscopy. The AS-OCT scanning protocol that only imaged the inferior quadrant showed the best area under the receiving operating characteristic curve (AUC 0.76, sensitivity 84%, specificity 69%) for detecting angle closure. Although technically easier to obtain, the protocol that only included the nasal-temporal quadrants had the lowest AUC (AUC 0.67, sensitivity 47%, specificity 88%), whereas scanning the superior-inferior quadrants showed high sensitivity for detecting angle closure (92%), but low specificity (54%). Using the results obtained in a research setting, the diagnostic performance of AS-OCT varied according to the adopted scanning protocol. The inferior quadrant-only protocol showed the best diagnostic performance but the low specificity would limit its use for population screening.

Novel Association of Smaller Anterior Chamber Width with Angle Closure in Singaporeans

To describe variations in anterior chamber width (ACW) and investigate its association with the presence of narrow angles. Cross-sectional study. We recruited 2047 subjects aged 50 years or more from a community polyclinic and 111 subjects with primary angle closure (PAC) or primary angle closure glaucoma (PACG) from an eye hospital in Singapore. All participants underwent gonioscopy, anterior chamber depth (ACD) and axial length (AL) measurement (IOLMaster; Carl Zeiss, Jena, Germany), and anterior-segment optical coherence tomography (AS-OCT, Visante, Carl Zeiss Meditec, Dublin, CA). Customized software was used to measure the ACW, defined as the distance between the scleral spurs in the horizontal (nasal-temporal) axis of AS-OCT scans. An eye was deemed to have narrow angles if the posterior trabecular meshwork was not visible for at least 180 degrees on non-indentation gonioscopy with the eye in the primary position. Anterior chamber width and narrow angles. Data on 1465 community-based subjects were available for analysis. Anterior chamber width was significantly smaller in women compared with men (11.70 mm vs. 11.81 mm, respectively, P<0.001) and decreased significantly with age (P for trend <0.001). Significant predictors of smaller ACW were lower educational level, lower body mass index, shorter AL, shallower ACD, and Chinese race. Of the 1465 subjects, 315 (21.5%) had narrow angles on gonioscopy. Mean ACW was smaller in eyes with narrow angles compared with those without narrow angles (11.60 mm vs. 11.80 mm, P<0.001). The age- and gender-adjusted odds ratio for the highest quartile compared with the lower 3 quartiles of ACW with the presence of narrow angles was 3.4 (95% confidence interval, 2.3-5.0; P for trend <0.001). Hospital-based subjects with PAC/PACG had even smaller ACW than community subjects with narrow angles (11.33 mm vs. 11.60 mm, P<0.001). In this cross-sectional study, ACW was smaller in women, Chinese persons, and older persons, and was associated with narrow angles in 2 different study populations. These data suggest that a smaller ACW may represent a novel risk indicator for angle closure.

Demonstration of Angle Widening Using EyeCam After Laser Peripheral Iridotomy in Eyes With Angle Closure

To evaluate EyeCam in detecting changes in angle configuration after laser peripheral iridotomy (LPI) in comparison to gonioscopy, the reference standard. Prospective comparative study. Twenty-four subjects (24 eyes) with primary angle-closure glaucoma (PACG) were recruited. Gonioscopy and EyeCam (Clarity Medical Systems) imaging of all 4 angle quadrants were performed, before and 2 weeks after LPI. Images were graded according to angle structures visible by an observer masked to clinical data or the status of LPI, and were performed in a random order. Angle closure in a quadrant was defined as the inability to visualize the posterior trabecular meshwork. We determined the number of quadrants with closed angles and the mean number of clock hours of angle closure before and after LPI in comparison to gonioscopy. Using EyeCam, all 24 eyes showed at least 1 quadrant of angle widening after LPI. The mean number of clock hours of angle closure decreased significantly, from 8.15 +/- 3.47 clock hours before LPI to 1.75 +/- 2.27 clock hours after LPI (P < .0001, Wilcoxon signed rank test). Overall, gonioscopy showed 1.0 +/- 1.41 (95% CI, 0.43-1.57) quadrants opening from closed to open after LPI compared to 2.0 +/- 1.28 (95% CI, 1.49-2.51, P = .009) quadrants with EyeCam. Intra-observer reproducibility of grading the extent of angle closure in clock hours in EyeCam images was moderate to good (intraclass correlation coefficient 0.831). EyeCam may be used to document changes in angle configuration after LPI in eyes with PACG.

Distinctive Findings in a Patient With Axenfeld–Rieger Syndrome Using High-Resolution AS-OCT

Some distinct findings of a patient with Axenfeld-Rieger syndrome from the anterior chamber angle images by high-resolution anterior segment optical coherence tomography (AS-OCT) are described. The typical anterior segment anomalies of Axenfeld-Rieger syndrome, including iris atrophy, posterior embryotoxon, peripheral bridging tissue bands, trabecular meshwork elongation, and high insertion of the iris root into the posterior trabecular meshwork, can be visualized clearly on AS-OCT images. Specifically, the high-resolution mode of the AS-OCT program had improved performance in outlining finer structures such as the distinctive endothelial membrane covering the iris in Axenfeld-Rieger syndrome, which enabled better understanding of the pathophysiology in the patient. The high-resolution imaging and non-contact method of AS-OCT make it an effective and feasible option in the diagnosis and evaluation of Axenfeld-Rieger syndrome.

Quantitative Iris Parameters and Association with Narrow Angles

To investigate the relationship between quantitative iris parameters (iris curvature [I-Curv], iris area [I-Area], and iris thickness) and the presence of narrow angles. Cross-sectional, community-based study. We recruited 2047 subjects >50 years old without ophthalmic symptoms from a community clinic in Singapore. All subjects underwent gonioscopy and anterior segment optical coherence tomography (AS-OCT) under dark conditions. An eye was considered to have narrow angles if the posterior pigmented trabecular meshwork was not visible for >/=180 degrees on nonindentation gonioscopy with the eye in the primary position. Customized software was used on horizontal AS-OCT scans to measure I-Curv, I-Area, and iris thickness 750 mum (IT750) and 2000 mum (IT2000) from the scleral spur. The average of both temporal and nasal measured values of the right eye was used for analysis. The association between iris parameters and narrow angles on gonioscopy. Iris parameters from 1465 eyes (71.6%) were available for analysis. Of these, 315 subjects (21.5%) had narrow angles. The mean I-Curv (0.366 vs 0.259 mm; P<0.020), IT750 (0.476 vs 0.453 mm; P<0.001), and IT2000 (0.491 vs 0.482 mm; P = 0.010) were greater in persons with than without narrow angles. After adjusting for age, gender, anterior chamber depth, axial length, and pupil size, the greater I-Curv, I-Area, IT750, and IT2000 were significantly associated with narrow angles (odds ratio [OR] 2.5 and 95% confidence interval [CI], 1.3-5.1; OR, 2.7 and 95% CI, 1.6-4.8; OR, 2.6 and 95% CI, 1.6-4.1; OR, 2.7 and 95% CI, 1.5-4.7, comparing 4th with 1st quartile for each parameter, respectively). In stratified analysis, women and subjects aged >/=60 years had stronger associations for most iris parameters with narrow angles than men and younger subjects. Quantitative iris parameters (I-Curv, I-Area, and iris thickness) are independently associated with narrow angles, particularly in women and older subjects. These data provide further insights into the pathogenesis of angle closure in Singaporeans. Proprietary or commercial disclosure may be found after the references.

Comparison of Slitlamp Optical Coherence Tomography and Scanning Peripheral Anterior Chamber Depth Analyzer to Evaluate Angle Closure in Asian Eyes

To evaluate the effectiveness of slitlamp optical coherence tomography (SL-OCT) and Scanning Peripheral Anterior Chamber depth analyzer (SPAC) in detecting angle closure, using gonioscopy as the reference standard. A total of 153 subjects underwent gonioscopy, SL-OCT, and SPAC. The anterior chamber angle (ACA) was classified as closed on gonioscopy if the posterior trabecular meshwork could not be seen; with SL-OCT, closure was determined by contact between the iris and angle wall anterior to the scleral spur; and with SPAC by a numerical grade of 5 or fewer and/or a categorical grade of suspect or potential. A closed ACA was identified in 51 eyes with gonioscopy, 86 eyes with SL-OCT, and 61 eyes with SPAC (gonioscopy vs SL-OCT, P < .001; gonioscopy vs SPAC, P = .10; SL-OCT vs SPAC, P < .001; McNemar test). Of the 51 eyes with a closed ACA on gonioscopy, SL-OCT detected a closed ACA in 43, whereas SPAC identified 41 (P = .79). An open angle in all 4 quadrants was observed in 102 eyes with gonioscopy, but SL-OCT and SPAC identified 43 and 20 of these eyes, respectively, as having angle closure. The overall sensitivity and specificity for SL-OCT were 84% and 58% vs 80% and 80% for SPAC. Using gonioscopy as the reference, SL-OCT and SPAC showed good sensitivity for detecting eyes at risk of angle closure.

Screening for Narrow Angles in the Singapore Population: Evaluation of New Noncontact Screening Methods

To assess the screening effectiveness of 3 new noncontact devices, the scanning peripheral anterior chamber depth analyzer (SPAC) (Takagi, Nagano, Japan), which measures peripheral anterior chamber depth (ACD); IOLMaster (Carl Zeiss Meditec, Jena, Germany), which measures central ACD; and Visante anterior segment optical coherence tomography (AS-OCT) (Visante, Carl Zeiss Meditec, Dublin, CA), which images the angles, and to compare these instruments with gonioscopy in identifying people with narrow angles (NAs). Cross-sectional, observational, community-based study. Phakic subjects aged >or=50 years without ophthalmic symptoms who were recruited from a community polyclinic in Singapore. All subjects underwent examination with SPAC, IOLMaster, and AS-OCT in the dark by a single operator. Gonioscopy was performed by an ophthalmologist masked to the instruments' findings. The area under the curve (AUC) receiver operating characteristic (ROC) was generated to assess the performance of these tests in detecting people with a NA in either eye. Eyes were classified as having NAs by gonioscopy if the posterior pigmented trabecular meshwork could be seen for <or=2 quadrants of the angle circumference with or without peripheral anterior synechiae. A total of 2052 subjects were examined and underwent all 3 tests. The prevalence of a NA in at least 1 eye diagnosed by gonioscopy was 20.4% (422 subjects). The AUC for the SPAC using a numeric grade <5 as a cutoff was 0.83 (95% confidence interval [CI], 0.82-0.85), with a sensitivity of 90.0% (95% CI, 86.8-92.7) and a specificity of 76.6% (95% CI, 74.4-78.6). The AUC for the IOLMaster at an ACD cutoff of <2.87 mm was 0.83 (95% CI, 0.81-0.85), with a sensitivity of 87.7% (95% CI, 84.2-90.7) and a specificity of 77.7% (95% CI, 75.6-79.7). The AUC for the AS-OCT was 0.76 (95% CI, 0.74-0.78), with a sensitivity of 88.4% (95% CI, 84.9-91.3) and a specificity of 62.9% (95% CI, 60.5-65.2). The low specificity found with the SPAC, IOLMaster, and AS-OCT may limit the usefulness of these devices in screening for NAs.

Risk factors for early angle-closure disease in a Burmese population: the Meiktila Eye Study

To determine risk factors for early angle-closure disease (AD) in a Burmese population. A cross-sectional, population-based survey of the inhabitants, 40 years of age and over, from villages in the Meiktila District was performed; 2481 eligible participants were identified, 2076 participated in the study, and 2050 could be categorized as having early AD (defined by the presence of so-called occludable angles (<90 degrees of posterior trabecular meshwork visible on gonioscopy), but without glaucomatous optic neuropathy). The ophthalmic examination included Snellen visual acuity, slit-lamp examination, tonometry, gonioscopy, biometry, and dilated stereoscopic fundus examination. The mean axial length (AL) and anterior chamber depth (ACD) in those with occludable angles were 21.9 and 2.60 mm, respectively; in those with non-occludable angles, the corresponding lengths were 22.74 and 2.84 mm, respectively (P<0.001 for both comparisons). In the univariate analyses, age, female gender, nuclear and cortical cataract, steeper corneal curvature, more anterior lens position, and myopia were also significantly associated with occludability. In the multivariate analysis, age, AL, ACD, and nuclear cataract were significantly associated with occludability. In this Burmese population, those with occludable angles had significantly shorter ALs, ACDs, and thicker lenses than those without occludable angles. In multivariate analysis, increasing age, decreasing AL, decreasing ACD, and nuclear cataract were significant predictors of early AD. The presence of nuclear cataract per se should raise clinical suspicion of the possibility of AD in this population.

Comparison of Gonioscopy and Anterior Segment Ocular Coherence Tomography in Detecting Angle Closure in Different Quadrants of the Anterior Chamber Angle

To compare the performance of gonioscopy and anterior segment (AS) optical coherence tomography (OCT) in detecting angle closure in the different quadrants of the anterior chamber angle (ACA). Cross-sectional observational study. Five hundred two consecutive subjects more than 50 years of age with no previous ophthalmic problems recruited from a community clinic in Singapore. All subjects underwent gonioscopy and AS OCT imaging in the dark. Using gonioscopy, the ACA was graded using the Scheie system by a single examiner masked to AS OCT findings. The ACA in a particular quadrant was classified as closed if the posterior trabecular meshwork could not be seen on gonioscopy. A closed ACA on AS OCT imaging was defined by the presence of any contact between the iris and angle wall anterior to the scleral spur. After excluding eyes with poor image quality, a total of 423 right eyes were included in the analysis. A closed angle in at least 1 quadrant was observed in 59% of the eyes by AS OCT and in 33% of the eyes by gonioscopy (P<0.001), with fair agreement between the two methods (kappa = 0.40). The frequency of closed angles by AS OCT and gonioscopy were 48% versus 29% superiorly, 43% versus 22% inferiorly, 18% versus 14% nasally, and 12% versus 20% temporally, respectively. Of the 119 of 1692 quadrants that were closed on gonioscopy but open on AS OCT, a steep iris profile was present in 61 (51%) of 119 quadrants on AS OCT, and of the 276 of 1692 quadrants that were open on gonioscopy but closed on AS OCT, 196 (71%) of 276 quadrants showed short iridoangle contact on AS OCT. The highest rates of closed angles on gonioscopy and AS OCT images were observed in the superior quadrant. Anterior segment OCT tended to detect more closed ACAs than gonioscopy, particularly in the superior and inferior quadrants. Variations in the iris profile and level of iridoangle contact also may explain some of the differences seen between gonioscopy and AS OCT.

Laser Peripheral Iridotomy in Primary Angle-Closure Suspects: Biometric and Gonioscopic Outcomes: The Liwan Eye Study

Purpose To assess the immediate effect of laser peripheral iridotomy (LPI) and mechanisms of angle closure in a population-based study of primary angle closure (PAC) suspects. Design Prospective interventional study. Participants People identified as PAC suspects aged 50 to 79 years from a population-based survey in Guangzhou, China. Intervention Laser peripheral iridotomy was performed in 1 randomly selected eye. Examinations were carried out before and 2 weeks after the intervention. Main Outcome Measures Intraocular pressure (IOP), ultrasound biometry, optical pachymetry, and gonioscopy. Results A total of 72 people with bilateral suspected PAC participated in the study. Mean IOP decreased by 3 mmHg (P<0.001), but axial anterior chamber depth did not change significantly (P = 0.784) after LPI. Median limbal anterior chamber depth increased from 15% to 25% of peripheral corneal thickness (P<0.001, Wilcoxon signed-rank test). Median iridotrabecular angle width increased from 0° to 10° in the superior quadrant and from 10° to 30° in the inferior quadrant (P<0.001). Nevertheless, 14 eyes (19.4%) still had 3 or more quadrants in which the posterior (usually pigmented) trabecular meshwork could not be seen after laser iridotomy. Conclusions This study confirms that LPI results in a significant increase in the angle width in Chinese people with narrow angles. However, one fifth of eyes had residual angle closure after LPI. Although this report confirms that iridotomy widens the anterior chamber angle in most PAC suspects, long-term prospective studies with a larger sample size are required to determine if the risks of PAC glaucoma and other related pathologic sequelae are reduced after prophylactic LPI and to investigate the risk-to-benefit ratio before recommending widespread use of prophylactic LPI in this population. To assess the immediate effect of laser peripheral iridotomy (LPI) and mechanisms of angle closure in a population-based study of primary angle closure (PAC) suspects. Prospective interventional study. People identified as PAC suspects aged 50 to 79 years from a population-based survey in Guangzhou, China. Laser peripheral iridotomy was performed in 1 randomly selected eye. Examinations were carried out before and 2 weeks after the intervention. Intraocular pressure (IOP), ultrasound biometry, optical pachymetry, and gonioscopy. A total of 72 people with bilateral suspected PAC participated in the study. Mean IOP decreased by 3 mmHg (P<0.001), but axial anterior chamber depth did not change significantly (P = 0.784) after LPI. Median limbal anterior chamber depth increased from 15% to 25% of peripheral corneal thickness (P<0.001, Wilcoxon signed-rank test). Median iridotrabecular angle width increased from 0° to 10° in the superior quadrant and from 10° to 30° in the inferior quadrant (P<0.001). Nevertheless, 14 eyes (19.4%) still had 3 or more quadrants in which the posterior (usually pigmented) trabecular meshwork could not be seen after laser iridotomy. This study confirms that LPI results in a significant increase in the angle width in Chinese people with narrow angles. However, one fifth of eyes had residual angle closure after LPI. Although this report confirms that iridotomy widens the anterior chamber angle in most PAC suspects, long-term prospective studies with a larger sample size are required to determine if the risks of PAC glaucoma and other related pathologic sequelae are reduced after prophylactic LPI and to investigate the risk-to-benefit ratio before recommending widespread use of prophylactic LPI in this population.

Detection of Primary Angle Closure Using Anterior Segment Optical Coherence Tomography in Asian Eyes

To evaluate noncontact anterior segment optical coherence technology (AS-OCT) as a qualitative method of imaging the anterior chamber angle and to determine its ability to detect primary angle closure when compared with gonioscopy in Asian subjects. Prospective observational case series. Two hundred three subjects were recruited from glaucoma clinics in Singapore with diagnoses of primary angle closure, primary open-angle glaucoma, ocular hypertension, or cataract. Both eyes (if eligible) of each patient were included in the study. Exclusion criteria were pseudophakia or previous glaucoma surgery. Images of the nasal, temporal, and inferior angles were obtained with AS-OCT in dark and then light conditions. Gonioscopic angle width was graded using the Spaeth classification for each quadrant in low lighting conditions. Angle closure was defined by AS-OCT as contact between the peripheral iris and angle wall anterior to the scleral spur and by gonioscopy as a Spaeth grade of 0 degree (posterior trabecular meshwork not visible). Comparison of the 2 methods in detecting angle closure was done by eye and by individual. Sensitivities and specificities of AS-OCT were calculated using gonioscopy as the reference standard. Complete data were available for 342 eyes of 200 patients. Of the patients, 70.9% had a clinical diagnosis of treated or untreated primary angle closure. Angle closure in > or =1 quadrants was detected by AS-OCT in 142 (71%) patients (228 [66.7%] eyes) and by gonioscopy in 99 (49.5%) patients (152 [44.4%] eyes). The inferior angle was closed more frequently than the nasal or temporal quadrants using both AS-OCT and gonioscopy. When performed under dark conditions, AS-OCT identified 98% of those subjects found to have angle closure on gonioscopy (95% confidence interval [CI], 92.2-99.6) and led to the characterization of 44.6% of those found to have open angles on gonioscopy to have angle closure as well. With gonioscopy as the reference standard, specificity of AS-OCT in the dark was 55.4% (95% CI, 45.2-65.2) for detecting individuals with angle closure. Anterior segment OCT is a rapid noncontact method of imaging angle structures. It is highly sensitive in detecting angle closure when compared with gonioscopy. More persons are found to have closed angles with AS-OCT than with gonioscopy.

Immunolocalization of prostanoid EP receptor isotypes in human trabecular meshwork

Purpose. To assess the localization of the EP-type prostanoid receptors in the human trabecular meshwork (TM) and to determine their spatial distribution in relation to the contractile α-smooth muscle actin fibres.Methods. Cryosections of human anterior segments were obtained from 17 different donors and immunostained with different EP receptor subtype specific antibodies. Double staining for the EP2 receptor and smooth muscle actin was carried out. Western blots of TM protein samples were studied.Results. No specific staining for the EP1 receptor was observed. The antibodies against the EP2 receptor revealed in all donors intense staining of human trabecular cells throughout the meshwork. EP3 receptor specific staining was not detected. EP4 immunostaining was confined to the corneo-scleral region near Schwalbe's line. On western blots, the EP2 receptor was detected. In the posterior TM, the EP2 receptor staining was associated with the dense network of actin fibres.Conclusions. These immunocytochemical results present evidence that the EP2 receptor is the most abundantly expressed isotype of the PGE receptors in the human TM. This conclusion is in agreement with our previous findings at the transcript level. The relaxant responses of the TM to application of EP2 receptor agonists, and flow enhancement evoked by prostaglandin PGE1, may be explained by the close spatial association of the EP2 receptor with actin fibres.

Angle-closure glaucoma in an urban population in southern india: The andhra pradesh eye disease study

Objective To assess the prevalence and features of angle-closure glaucoma (ACG) in an urban population in southern India. Design A population-based, cross-sectional study. Participants A total of 2522 (85.4% of those eligible) persons of all ages, including 1399 persons 30 years of age or older, from 24 clusters representative of the population of Hyderabad city. Testing The participants underwent an interview and detailed eye examination that included logarithm of minimum angle of resolution visual acuity, refraction, slit-lamp biomicroscopy, applanation tonometry, and gonioscopy; pupil dilatation and stereoscopic fundus evaluation was performed if the risk of angle-closure as a result of dilatation was not believed to be imminent. Humphrey threshold 24-2 visual fields (Humphrey Instruments Inc., San Leandro, CA) were performed when indicated by standardized criteria for disc damage or if intraocular pressure (IOP) was 22 mmHg or more. Main outcome measures An occludable angle was defined as pigmented posterior trabecular meshwork not visible by gonioscopy in three quarters or more of the angle circumference. Manifest primary angle-closure glaucoma (PACG) was defined as IOP of 22 mmHg or more or glaucomatous optic disc damage with visual field loss in the presence of an occludable angle. An IOP of 22 mmHg or more or glaucomatous optic disc damage in the presence of an occludable angle secondary to an obvious cause was defined as secondary ACG. Results Manifest PACG and occludable angles without ACG were present in 12 and 24 participants, respectively, with age- and gender-adjusted prevalence (95% confidence interval [CI]) of 0.71% (0.34%–1.31%) and 1.41% (0.73%–2.09%) in participants 30 years of age or older, and 1.08% (0.36%–1.80%) and 2.21% (1.15%–3.27%) in participants 40 years of age or older, respectively. With multivariate analysis, the prevalence of these two conditions considered together increased significantly with age ( P < 0.001); although not statistically significant, these were more common in females (odds ratio 1.70; 95% CI, 0.82–3.54) and in those belonging to lower socioeconomic strata as compared with middle and upper strata (odds ratio, 1.82; 95% CI, 0.88–3.74). The odds of manifest PACG were higher in the presence of hyperopia of more than 2 diopters ([D]; odds ratio, 3.69; 95% CI, 0.89–15.2). Only four of 12 participants (33.3%) with manifest PACG had been previously diagnosed, and one of 12 (8.3%) had peripheral iridotomy performed previously. Manifest PACG had caused blindness in one or both eyes in five of these 12 participants (41.7%); best-corrected distance visual acuity less than 20/400 in one or both eyes in four patients, and acuity less than 20/200 in one eye in another patient. Most (83.3%) of those with manifest PACG could be classified as having chronic form of the disease. We may have underestimated manifest PACG because visual fields were per- formed only on those with clinical suspicion of optic disc damage. Secondary ACG was present in two participants. Conclusions The prevalence of PACG in this urban population in southern India is close to that reported recently in a Mongolian population. A large proportion of the PACG in this population was undiagnosed and untreated. Because visual loss resulting from PACG is potentially preventable if peripheral iridotomy or iridectomy is performed in the early stage, strategies for early detection of PACG could reduce the high risk of blindness resulting from PACG seen in this urban population in India.

Glaucoma: Long Term Complications of Infantile Aphakia

65 children with glaucoma following cataract surgery were studied. Patients with bilateral lensectomy followed by bilateral glaucoma, bilateral lensectomy followed by unilateral glaucoma, and unilateral lens surgery followed by unilateral glaucoma were identified. Vitreous cutting instruments were used for 80% of the lensectomy procedures. 77% of patients were operated in the first year of life, and 87% of patients were recognized to have glaucoma two or more years after their lensectomy. Preoperative gonioscopy revealed no consistent angle abnormality, while postoperative gonioscopy revealed open angles associated with a near constant (96%) but variable abnormality. This angle defect was characterized by blockage of the trabecular meshwork by an acquired anterior repositioning of the iris root over the posterior trabecular meshwork associated with other secondary angle abnormalities.Surgical treatment of pediatric aphakic glaucoma was most successful with a trabeculectomy or with placement of a glaucoma implant.

The development of human trabecular meshwork

The fetal development of the trabecular meshwork of the human eye was quantitatively studied by light and electron microscopy. From the 20th fetal week onward, the progressive thickening of the trabecular meshwork was achieved mainly by the widening of intertrabecular spaces, whereas the thickness and the number of trabeculae were almost constant. Significant alterations in the number of trabecular meshwork cells did not occur with development. However, a decrease in trabecular meshwork cellularity occurred by the widening of intertrabecular spaces. As development proceeded, there was an increase in the proportion of the width of the posterior trabecular meshwork, which is the main site of aqueous drainage, in accordance with the increase of aqueous production.

Argon laser trabeculoplasty controls one third of cases of progressive, uncontrolled, open angle glaucoma for 5 years.

Seventy-eight patients (109 eyes) with progressive glaucoma had argon laser trabeculoplasty as a substitute for filtration surgery and were then followed up for a minimum of 5 years. One hundred spots were placed at the anterior margin of the posterior trabecular meshwork over 360 degrees. Consecutive cases between 1980 and 1985 were reviewed, 95% of treated cases being included in the final analysis. Eighty-two eyes had primary open angle glaucoma. If only the group with primary open angle glaucoma is considered, the failure rate the first year was 19%. After that, the failure rate was approximately eight per year. At the end of 5 years, 65% of all eyes had failed. At the end of 10 years, data were available on 84 of the original 109 treated eyes; in 80 treatment had failed, and four were still receiving medical therapy.