Longitudinal changes in anterior chamber depth and axial length in Asian subjects after trabeculectomy surgery.

BACKGROUND/AIMS: To investigate longitudinal changes in anterior chamber depth (ACD) and axial length (AXL) over 5 years after trabeculectomy surgery in Asian patients with primary glaucoma, and to identify factors associated with these changes. METHODS: In this prospective cohort study, phakic subjects with primary glaucoma who underwent trabeculectomy had ACD and AXL measured over 5 years. The effect of intraocular pressure (IOP) on ACD and AXL was determined. Subjects were divided into two groups (high or low fluctuation of ACD/AXL) and factors were compared to determine if there were factors associated with greater fluctuation. RESULTS: 122 subjects were analysed. The majority of subjects were male (75.4%) and Chinese (77%). ACD and AXL were shallower/shorter compared with baseline at all postoperative visits, with a mean decrease of 0.11 mm (95% CI 0.07 to 0.15 mm, p<0.01) and 0.16 mm (95%CI 0.11 to 0.20 mm, p<0.01), respectively. Patients with primary open angle glaucoma (POAG) had higher odds of fluctuations in longitudinal measurements of ACD (OR=8.74, p<0.01) and AXL (OR=5.60, p<0.01) compared with patients with primary angle closure glaucoma. For every 1 mm Hg decrease in IOP, ACD and AXL decreased by 0.02 mm (p<0.01) and 0.01 mm (p=0.03), respectively, for POAG patients with emmetropia or mild myopia. CONCLUSIONS: Trabeculectomy resulted in a decrease in both ACD and AXL, and these changes were persistent over a period of 5 years.

The Singapore 5-fluorouracil trial: intraocular pressure outcomes at 8 years.

OBJECTIVE: To report the 8-year outcomes of Asian subjects who underwent trabeculectomy augmented by intraoperative 5-fluorouracil (5-FU) or placebo. DESIGN: Retrospective review of a randomized controlled trial. PARTICIPANTS: Subjects with primary open-angle or angle-closure glaucoma. METHODS: Study subjects were prospectively followed up for 3 years. After the last subject recruited had completed 8 years of follow-up, the charts of all subjects were reviewed to capture data from the year 3 visit onward. Kaplan-Meier survival function with Cox regression was performed to identify risk factors associated with trabeculectomy failure at 8 years. MAIN OUTCOME MEASURES: The primary outcome was trabeculectomy failure defined as intraocular pressure (IOP) >21 or <6 mmHg on 2 consecutive occasions after the first 6 weeks after surgery, repeat glaucoma surgery, or loss of light perception. Further end points were defined at IOP levels >17 and >14 mmHg. Secondary outcomes included IOP at 8 years and number of glaucoma medications. Complete success was defined using IOP end points ≤ 21, ≤ 17, or ≤ 14 mmHg at 8 years without medications. RESULTS: Of the 243 enrolled subjects, 170 (70.0%) completed 8 years follow-up, 86 in the 5-FU and 84 in the placebo group. There was no significant difference in failure rates at 8 years for the failure definitions of IOP >21 mmHg (11.6% of the 5-FU group vs. 16.7% of the placebo group; P = 1.00), IOP >17 mmHg (23.3% of the 5-FU group vs. 31% of the placebo group; P = 0.78), and IOP >14 mmHg (46.5% of the 5-FU group vs. 58.3% of the placebo group; P = 0.37). Mean IOP at 8 years was 13.7 mmHg in the 5-FU versus 14.4 mmHg in the placebo group (P = 0.24). Mean number of medications was 0.65 drops in the 5-FU versus 0.93 drops in the placebo group (P = 0.06). Complete success with IOP ≤ 21 mmHg at 8 years was achieved in 48 subjects (55.8%) in the 5-FU and 33 subjects (39.3%) in the placebo group (P = 0.09). Absence of bleb microcysts at 1 year, preoperative IOP, and number of bleb needlings performed within the first year were significantly associated with failure. CONCLUSIONS: There was no significant difference in IOP between the 5-FU and the placebo group at 8 years. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Efficacy and safety of collagen matrix implants in phacotrabeculectomy and comparison with mitomycin C augmented phacotrabeculectomy at 1 year.

BACKGROUND: To assess the efficacy and safety of collagen matrix implant (Ologen) in phacotrabeculectomy. DESIGN: Prospective, non-randomized, comparative study. PARTICIPANTS: Sixty-six Asian patients. METHODS: Thirty three consecutive patients underwent phacotrabeculectomy with Ologen implant and intraocular lens implantation, and 33 subjects recruited as controls underwent surgery with mitomycin C augmentation. MAIN OUTCOME MEASURES: The primary outcome measure was postoperative intraocular pressure at month 12. Additional postoperative treatments, such as bleb needling, and adverse events were secondary outcomes. RESULTS: The overall percentage reduction in intraocular pressure was 13% (95% confidence interval 6.7-19.2) in the Ologen group and 26% (95% confidence interval 14.8-37.9) in the mitomycin C group (P = 0.05). At 1 year after surgery (after adjusting for baseline differences), intraocular pressure decreased by 4.2 mmHg (95% confidence interval 2.8-5.6 mmHg) and 5.6 mmHg (95% confidence interval 4.2-7.0 mmHg), respectively (P = 0.16). Needling with 5-fluorouracil was required more often in the Ologen group (39% vs. 6%; P = 0.003). There was similar frequency (<10%) of adverse events in both groups, and there were no complications directly related to the Ologen implant. The blebs in the mitomycin C group had greater central area (P = 0.005), maximal area (P = 0.01) and height (P = 0.005), and were less vascular (P = 0.023) than the Ologen blebs. CONCLUSIONS: At 1 year, the overall performance of Ologen in combined phacotrabeculectomy was suboptimal compared with combined surgery with mitomycin C. Eyes in the Ologen group required more frequent bleb needling procedures.

Initial management of acute primary angle closure: a randomized trial comparing phacoemulsification with laser peripheral iridotomy.

PURPOSE: To compare the 2-year efficacy of phacoemulsification and intraocular lens implant (phaco/IOL) with laser peripheral iridotomy (LPI) in the early management of acute primary angle closure (APAC) and coexisting cataract. DESIGN: Randomized, controlled trial. PARTICIPANTS: We included 37 subjects presenting with APAC who had responded to medical treatment such that intraocular pressure (IOP) was ≤30 mmHg within 24 hours, and had cataract with visual acuity of ≤6/15. MAIN OUTCOME MEASURES: The primary outcome measure was failure of IOP control defined as IOP between 22 to 24 mmHg on 2 occasions (readings taken within 1 month of each other) or IOP ≥25 mmHg on 1 occasion, either occurring after week 3. Secondary outcome measures were complications, degree of angle opening, amount of peripheral anterior synechiae, visual acuity, and corneal endothelial cell count (CECC). METHODS: Subjects were randomized to receive either LPI or phaco/IOL in the affected eye within 1 week of presentation and were examined at fixed intervals over 24 months. Patients underwent a standardized examination that included Goldmann applanation tonometry, gonioscopy, and CECC measurements. Logistic regression was used to estimate the effect of treatment on failure of IOP control. Time to failure was evaluated using the Kaplan-Meier technique and Cox regression was used to estimate the relative risk of failure. RESULTS: There were 18 patients randomized to LPI and 19 to phaco/IOL. The average age of subjects was 66.0±9.0 years and mean IOP after medical treatment was 14.5±6.9 mmHg. The 2-year cumulative survival was 61.1% and 89.5% for the LPI and phaco/IOL groups, respectively (P = 0.034). There was no change in CECC for either group from baseline to month 6. There was 1 postoperative complication in the phaco/IOL group compared with 4 in the LPI group (P = 0.180). CONCLUSIONS: Performed within 1 week in patients with APAC and coexisting cataract, phaco/IOL resulted in lower rate of IOP failure at 2 years compared with LPI.

Cataract surgery after trabeculectomy: the effect on trabeculectomy function.

OBJECTIVE: To determine whether the timing of cataract surgery after trabeculectomy has an effect on trabeculectomy function in terms of intraocular pressure control. METHODS: This was a cohort study nested within a randomized clinical trial. There were 235 participants with glaucoma who had a single previous trabeculectomy augmented with either intraoperative 5-fluorouracil or placebo. Cataract surgery with intraocular lens implantation was performed on participants judged to have significant lens opacity. Cox regression was performed to evaluate the effect of time between trabeculectomy and cataract surgery on the time to trabeculectomy failure, after adjusting for other relevant risk factors. The main outcome measure was time to failure of trabeculectomy, defined as an intraocular pressure of greater than 21 mm Hg. RESULTS: Of the 235 participants, 124 (52.7%) underwent subsequent cataract surgery. The median time from trabeculectomy to cataract surgery for these patients was 21.7 months (range, 4.6-81.9 months). The median follow-up period was 60 months (range, 28-84 months) for the cataract surgery group and 48 months (range, 12-84 months) for the non-cataract surgery group. Cox regression showed that the time from trabeculectomy to cataract surgery was significantly associated with time to trabeculectomy failure (hazard ratio, 1.73 [95% CI, 1.05-2.85]; P = .03). The adjusted declining hazard ratios for risk of subsequent trabeculectomy failure when cataract surgery was performed 6 months, 1 year, and 2 years after trabeculectomy were 3.00 (95% CI, 1.11-8.14), 1.73 (95% CI, 1.05-2.85), and 1.32 (95% CI, 1.02-1.69), respectively. CONCLUSIONS: Cataract surgery after trabeculectomy increases the risk of trabeculectomy failure, and this risk is increased if the time between trabeculectomy and cataract surgery is shorter.

Central corneal thickness and glaucoma in East Asian people.

PURPOSE: To examine the association between central corneal thickness (CCT) and glaucoma. METHODS: This was a nested case-control study using 1090 subjects from an eye disease population survey in Singapore and 243 participants from a hospital glaucoma surgery clinical trial in Singapore. RESULTS: Mean CCT in 938 community subjects was 539 µm ± 32 µm, and in 12 community subjects with primary open angle glaucoma (POAG) the mean CCT was 545 µm ± 38 µm. In the hospital cohort, mean CCT was 552 µm ± 38 µm in 138 patients with POAG and 551 µm ± 33 µm in 105 patients with primary angle closure glaucoma (PACG). No individuals had undergone previous intraocular surgery or had other significant ocular pathology. Regression models showed POAG diagnosis was not associated with CCT (P = 0.42) or age (P = 0.062) in community subjects but was associated with IOP (P = 0.005). Similar analyses for hospital cases showed CCT to be significantly higher in both POAG and PACG (both P = 0.001), but this became nonsignificant after controlling for IOP and age (P = 0.26, POAG; P = 0.08, PACG). Both age (P = 0.043) and IOP (P = 0.001) were highly associated with hospital POAG; only IOP (P = 0.001) was associated with hospital PACG. Further regression analyses for community subjects showed diabetic status and pseudophakia had no significant effect on CCT (P = 0.33 and P = 0.11, respectively). CONCLUSIONS: The authors found no evidence to support the previous observation that thinner corneas may be independently associated with POAG or PACG. Age and IOP are significantly associated with CCT, and this should be taken into account by future studies investigating CCT as an independent risk factor for glaucoma diagnosis.

Population prevalence of tilted and torted optic discs among an adult Chinese population in Singapore: the Tanjong Pagar Study.

OBJECTIVE: To determine the prevalence of tilted and torted optic discs and associated risk factors among Chinese adults in Singapore. METHODS: As part of a population-based survey, optic disc stereophotographs of both eyes were obtained, and left eyes were analyzed using imaging software. A tilted optic disc was defined as an index of tilt (ratio of minimum to maximum optic disc diameter) less than 0.75. The angle of tilt was defined as the angle between the maximum and vertical optic disc diameter, and optic discs were graded as torted if the angle of tilt exceeded 15 degrees . RESULTS: Twenty-six of 739 subjects (3.5%) had tilted optic discs, and 478 (64.7%) had torted optic discs. Myopia was present in 23 of 26 eyes (88.5% [95% confidence interval, 69.9%-97.6%]) with tilted optic discs and in 211 of 661 eyes (31.9% [28.4%-35.6%]) without tilted optic discs (P < .001). On multivariate analysis, myopia (spherical equivalent) was a significant risk factor for tilted optic discs (P < .001). Index of tilt was not associated with corneal astigmatism or with cylindrical refractive error. Seventeen eyes (65.4%) with tilted optic discs had an optic disc morphologic abnormality, but none were glaucomatous. CONCLUSIONS: The prevalence of tilted optic discs among this Chinese population was 3.5%. Tilted optic discs were associated with myopia but not with glaucoma.

The singapore 5-Fluorouracil trabeculectomy study: effects on intraocular pressure control and disease progression at 3 years.

PURPOSE: To report 3-year results of a randomized, controlled trial comparing the use of a single application of 5-fluorouracil (5-FU) with placebo in trabeculectomy surgery. DESIGN: Prospective, randomized, double-blinded treatment trial. PARTICIPANTS: Two hundred forty-three Asian patients with primary open-angle or primary angle-closure glaucoma undergoing primary trabeculectomy. METHODS: One eye of each patient was randomized to receive either intraoperative 5-FU or normal saline (placebo) during trabeculectomy. MAIN OUTCOME MEASURES: Primary outcome measure was the level of intraocular pressure (IOP). Secondary outcomes were progression of visual field loss, rates of adverse events, and interventions after surgery. RESULTS: Of the 288 eligible patients, 243 were enrolled and 228 completed 3 years follow-up; 120 patients received 5-FU and 123 received placebo. Trial failure, according to predefined IOP criteria, was lower in the 5-FU group compared with the placebo group, although the difference was only significant with a failure criterion of IOP >17 mmHg (P = 0.0154). There was no significant difference in progression of optic disc and/or visual field loss over 36 months between 5-FU and placebo (relative risk [RR], 0.67; 95% confidence interval [CI], 0.34-1.31; P = 0.239). Uveitis occurred more often in the 5-FU-treated group (14/115 [12%] vs 5/120 [4%]; P = 0.032). CONCLUSIONS: This is the first masked, prospective, randomized trial reporting the effect of adjunctive 5-FU in trabeculectomy surgery in an East Asian population. The trial shows that an increased success rate can be achieved for several years after a single intraoperative treatment with 5-FU. We conclude that 5-FU is relatively safe and can be routinely used in low-risk East Asian patients. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any materials discussed in this article.

Screening for narrow angles in the singapore population: evaluation of new noncontact screening methods.

PURPOSE: 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). DESIGN: Cross-sectional, observational, community-based study. PARTICIPANTS: Phakic subjects aged >or=50 years without ophthalmic symptoms who were recruited from a community polyclinic in Singapore. METHODS: 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. MAIN OUTCOME MEASURES: Eyes were classified as having NAs by gonioscopy if the posterior pigmented trabecular meshwork could be seen for

Determinants of angle closure in older Singaporeans.

OBJECTIVES: To investigate systemic and ocular risk factors for angle closure (AC) in older Singaporeans and to determine if these risk factors are different in men vs women and in Chinese vs non-Chinese persons. METHODS: A cross-sectional study of 2042 subjects with phakia 50 years or older recruited from a primary care clinic in Singapore. Subjects completed a detailed questionnaire and underwent refraction, biometry, and gonioscopy. Univariate and multivariate analyses were performed to determine risk factors for AC. RESULTS: The prevalence of AC among this study population was 19.3% (n = 395); 89.4% (n = 1826) of the study population were Chinese. In univariate analysis, patients with AC were older, female, and of Chinese descent and had shorter axial length, lower body mass index, higher intraocular pressure, and shallower anterior chamber depth. In multivariate analysis, female sex (odds ratio [OR], 1.43; 95% confidence interval [CI], 1.06-1.92; P =.02), Chinese race/ethnicity (OR, 3.58; 95% CI, 2.03-6.29; P < .001), axial length (OR per millimeter increase, 0.69; 95% CI, 0.58-0.81; P<.001), and central anterior chamber depth of less than 2.80 mm vs at least 3.00 mm (OR, 42.5; 95% CI, 27.4-66.2; P<.001) were independently associated with AC. CONCLUSIONS: In this community-based study of older Singaporeans, statistically significant independent predictors of AC were female sex, shorter axial length, shallower central anterior chamber depth, and Chinese race/ethnicity. Sex and racial/ethnic differences in the risk of AC were not fully explained by sex and racial/ethnic variations in axial length or anterior chamber depth.

Assessment of the scleral spur in anterior segment optical coherence tomography images.

OBJECTIVE: To assess visibility of the scleral spur in anterior segment optical coherence tomography (AS-OCT) images. METHODS: This cross-sectional observational study included 502 participants aged 50 years or older who had no previous ophthalmic problems and were recruited from a community clinic in Singapore. All participants underwent gonioscopy and AS-OCT (Visante; Carl Zeiss Meditec, Dublin, California). Scleral spur location was assessed in AS-OCT images by 2 examiners with glaucoma subspecialty training and was defined as the point where there was an inward protrusion of the sclera with a change in curvature of its inner surface. RESULTS: Scleral spur location could be determined in 72% of the images of the right eye. Its location on AS-OCT images was less detectable in quadrants with a closed angle on gonioscopy and also in images obtained in the superior and inferior compared with the nasal and temporal quadrants (64%, 67%, 75%, and 80%, respectively; P < .001). CONCLUSIONS: The inability to detect the scleral spur may hamper quantitative analysis of anterior chamber angle parameters that are dependent on the location of this anatomical structure, particularly in the superior and inferior quadrants. New parameters independent of the scleral spur may be useful for detecting eyes at risk of angle closure.

National survey of ophthalmologists in Singapore for the assessment and management of asymptomatic angle closure.

PURPOSE: Approximately 10% of Chinese people older than 50 years in Singapore have asymptomatic narrow angles [also termed primary angle closure suspects (PACS)]. The aim of this study was to determine the attitudes and practices of ophthalmologists in Singapore regarding the management of these patients. METHODS: A nation wide questionnaire-based survey was conducted on all registered, practicing ophthalmologists in Singapore by electronic mail and post. An ophthalmologist was defined as a doctor who had completed at least 3 years of specialist training in ophthalmology and had passed the Master's Degree in Ophthalmology or equivalent examinations. The survey asked the ophthalmologists about the methods and criteria used for the diagnosis of angle closure. It also inquired about the management of PACS and opinions on the effectiveness of prophylactic laser peripheral iridotomy (LPI) in preventing both acute and chronic angle closure. RESULTS: A total of 126 out of 158 ophthalmologists responded (79.7% response rate). Of the respondents, 84.9% would advise prophylactic LPI for asymptomatic PACS; 84.9% believed that prophylactic LPI would prevent acute angle closure but only 44% thought that it could prevent the development of glaucomatous optic nerve damage. The preferred method of prophylactic LPI was sequential argon-YAG LPI. In assessing patients for angle closure, 85.4% used gonioscopy, 92.9% assessed anterior chamber depth, and 17.5% performed provocative tests. CONCLUSIONS: Ophthalmologists in Singapore vary in the method of assessment of patients with angle closure. Most believe that prophylactic LPI should be performed for asymptomatic PACS.

Comparison of anterior chamber depth measurements using the IOLMaster, scanning peripheral anterior chamber depth analyser, and anterior segment optical coherence tomography.

AIM: To compare anterior chamber depth measurements by three non-contact devices-the IOLMaster, scanning peripheral anterior chamber depth analyser (SPAC), and Visante anterior segment optical coherence tomography (AS-OCT) METHODS: Prospective, cross sectional study of 497 phakic subjects over 50 years of age attending a community clinic in Singapore. Anterior chamber depth of the right eye was measured using all three techniques by the same investigator. Depth measurements were made from the corneal epithelium to the anterior lens surface. The values obtained were compared using Bland-Altman analysis. RESULTS: 232 men and 265 women were examined (mean (SD) age, 63.4 (7.9) years). Mean anterior chamber depth was 3.08 (0.36) mm with IOLMaster, 3.10 (0.44) mm with SPAC, and 3.14 (0.34) mm with AS-OCT. A significant difference was present between the anterior chamber depth measurements recorded by the three devices (p<0.0001). Mean differences between the measurements were: AS-OCT v IOLMaster, 0.062 (0.007) mm (95% limits of agreement, -0.37 to 0.25 mm) (p<0.0001); AS-OCT v SPAC, 0.035 (0.011) mm (-0.44 to 0.51 mm) (p = 0.0001); SPAC v IOLMaster, 0.027 (0.012) mm (-0.57 to 0.50 mm) (p = 0.027). CONCLUSIONS: AS-OCT gave systematically deeper anterior chamber measurements than SPAC and IOL-Master. However, as the differences found were small they are unlikely to be clinically important.

Peripapillary atrophy after acute primary angle closure.

AIM: To determine the changes in peripapillary atrophy after episodes of acute primary angle closure (APAC). METHODS: Prospective observational study of 40 eyes in 38 patients of predominantly Chinese ethnicity. The mean (SD) intraocular pressure at the time of presentation was 51.7 (12) mm Hg (median, 55 mm Hg) and the mean duration of the symptoms was 37.7 (69.4) hours. A laser iridotomy was undertaken 3.2 (8.4) days after the APAC episode, leading to normalisation of intraocular pressure in all cases. Colour optic disc photographs taken at 2 and 16 weeks after APAC were examined morphometrically. Peripapillary atrophy was divided into alpha and beta zones. RESULTS: Comparing measurements at baseline with week 16, the minimum width of the alpha zone (0.013 (0.056) v 0.016 (0.001) arbitrary units; p = 0.23), the maximum width of the alpha zone (1.11 (1.31) v 1.31 (0.79) arbitrary units; p = 0.22), the minimum width of the beta zone (0.030 (0.122) v 0.033 (0.166) arbitrary units; p = 0.93), and the maximum width of the beta zone (0.62 (0.94) v 0.73 (0.98) arbitrary units; p = 0.42) did not vary significantly. The mean cup to disc ratio increased from 0.56 (0.05) to 0.62 (0.07) (p<0.0001) at the end of follow up. CONCLUSIONS: The alpha and beta zones of peripapillary atrophy did not enlarge markedly in patients after APAC, despite an enlargement of the optic cup during a follow up of four months.

Long-term outcomes in fellow eyes after acute primary angle closure in the contralateral eye.

PURPOSE: To determine the long-term outcome of the contralateral eye in Asian persons with a unilateral attack of acute primary angle closure (APAC). DESIGN: Cross-sectional observational case series. PARTICIPANTS: Seventy-nine individuals who were examined from 4 to 10 years after a unilateral episode of APAC at 2 Singapore hospitals. METHODS: All subjects underwent a complete eye examination. The optic discs were graded clinically and photographically for the presence of glaucomatous optic neuropathy, and automated visual field tests were assessed for damage. All visual fields and optic nerve photographs (when available) underwent a second evaluation by a masked glaucoma specialist, who assessed whether the changes were compatible with glaucoma. MAIN OUTCOME MEASURES: Glaucomatous optic neuropathy, intraocular pressure (IOP), and visual impairment (defined as best-corrected visual acuity of worse than 6/12). RESULTS: Ninety of 138 eligible patients (65.2%) with APAC were examined, 79 with unilateral attacks. Subjects were predominantly Chinese (n = 68; 86%). There were 54 females (68%), and mean age was 68.5+/-8.9 years (standard deviation) at the time of APAC, with a mean duration of 6.3+/-1.5 years from the time of the APAC episode to the study examination. The contralateral eyes of 7 patients (8.9%) had definite or probable glaucoma, 2 of whom were felt to have glaucoma in that eye at the time of the attack. Three eyes had markedly cupped optic discs (cup-to-disc ratio > or = 0.9). Thirteen eyes (16.9%) had best-corrected vision worse than 6/12, due to cataract in almost half the cases. Only 1 eye had vision < 6/60, the cause of which was corneal decompensation. One other patient had only a central island remaining with vision of 6/12. Mean IOP of the study participants was 15.7+/-4.7 mmHg, with 6 subjects (7.6%) having undergone trabeculectomy. CONCLUSIONS: Definite or probable glaucoma was present at the time of diagnosis in 2 (2.5%) fellow eyes and developed in an additional 5 (6.5%) with a mean follow-up of 6 years. More than 80% of this cohort retained good vision in the contralateral eye, in contrast to the eye that underwent APAC. Unoperated cataract accounted for most of the visual impairment in this group.

Lens opacity, thickness, and position in subjects with acute primary angle closure.

PURPOSE: To compare lens thickness (LT), lens position (LP), relative lens position (RLP), and degree and type of lens opacity between affected and fellow eyes of subjects with acute primary angle closure (APAC) to identify any differences in lens characteristics that may be contributory to the acute episode. In addition, axial length (AL) and anterior chamber depth (ACD) measurements were evaluated. METHODS: Seventy-three study subjects with unilateral APAC were treated with sequential laser iridotomy (LI) in both eyes. Two weeks after LI, ACD, LT, and AL measurements were made in both eyes using ultrasound pachymetry. LP was defined as ACD+1/2LT and RLP as LP/AL. The Lens Opacity Classification III (LOCS III) System was used for grading lens opacity. RESULTS: The subjects were 90% Chinese and 63% female. Mean age was 61.0+/-10.9 years. Significant differences between the affected and fellow eyes were found in the ACD (2.11+/-0.35 vs 2.18+/-0.23; P=0.02) and LP (4.61+/-0.47 vs 4.75+/-0.29; P=0.02). Cortical opacity was greater in fellow eyes (0.32+/-0.72 vs 0.53+/-0.95; P=0.02). There was no difference in LT, RLP, or degree of lens opacity in the nuclear and posterior subcapsular regions. CONCLUSIONS: Compared with fellow eyes, APAC-affected eyes have shallower ACD, more anterior LP, and less cortical opacity. These differences may be contributory to APAC.

Effect of trabeculectomy on lens opacities in an East Asian population.

OBJECTIVE: To examine the progression of lens opacity in Asian people after trabeculectomy and determine associated risk factors. METHODS: This was an observational case series of 243 people aged 36 to 82 years. Trabeculectomy was performed on 1 eye of each subject. Lens opacity was measured yearly using the Lens Opacification Classification System III. The main outcome measure was worsening of lens opacity defined as an increase of 2 or more Lens Opacification Classification System III units in any of the 3 lens regions, nuclear, cortical, and posterior subcapsular. Risk of progression was evaluated using logistic regression models. RESULTS: Data for 177 people were analyzed. One hundred seventeen (66%) of 177 subjects showed progression in opacity in any lens region at 3 years. Seventy-seven (66%) of 117 of those who progressed did so during the first year. Of these, 63 (82%) of 77 had lens opacity in the posterior subcapsular region. Factors associated with progression of posterior-subcapsular lens opacity at 1 year were diabetes (odds ratio, 2.4; 95% confidence interval, 1.0-5.4), use of antiglaucoma medication, dosage of topical steroid postoperatively, and being operated on by a trainee surgeon (odds ratio, 2.3; 95% confidence interval, 1.0-5.2). CONCLUSIONS: Trabeculectomy is associated with progression of lens opacity predominantly in the posterior subcapsular region. Modification of risk factors such as postoperative steroid use may delay progression.

Changes in the optic disc after acute primary angle closure.

PURPOSE: To evaluate the changes in optic disc morphology in the first 4 months after an episode of acute primary angle closure (APAC) using stereoscopic optic disc photography and computer-assisted planimetry. DESIGN: Prospective observational case series. PARTICIPANTS: Forty-seven Asian subjects with unilateral APAC who were successfully treated with laser peripheral iridotomy (LPI). MAIN OUTCOME MEASURES: Cup-to-disc ratio (CDR) and optic cup and neuroretinal rim areas. METHODS: Stereoscopic optic disc photographs were taken 2 and 16 weeks after LPI, and the images were analyzed by computer-assisted planimetry. The overall, quadrantic, and 30 degrees sector areas of the optic disc, CDR, and neuroretinal rim area were analyzed by 2 independent masked graders, and the mean of the readings was used to calculate changes in optic disc parameters. RESULTS: The majority of the subjects were female (66%) and Chinese (90%), and the mean age was 67.6+/-11.2 years (range, 40-94). In APAC eyes from week 2 to week 16, the mean CDR increased from 0.56+/-0.05 to 0.59+/-0.03 (P<0.001), and the mean neuroretinal rim area decreased from 1.74+/-0.31 mm2 to 1.59+/-0.27 mm2 (P<0.001). Quadrantic and sector analysis showed preferential loss of neuroretinal rim area at the superotemporal and inferotemporal areas. There was no significant change in optic disc parameters in the fellow eyes over the study period. CONCLUSIONS: This study demonstrated changes in optic disc morphology from week 2 to week 16 after an episode of APAC. The pattern of optic nerve damage demonstrated in our study was comparable with that seen in primary open-angle glaucoma and experimental glaucoma models.

Peripapillary retinal nerve fiber layer thickness variations with myopia.

PURPOSE: To determine the relationship between peripapillary retinal nerve fiber layer (RNFL) thickness and myopia using optical coherence tomography (OCT). DESIGN: Prospective observational case series. METHODS: One hundred thirty-two young males with myopia (spherical equivalent [SE], -0.50 to -14.25 diopters) underwent ophthalmic examination of one randomly selected eye. Optical coherence tomography (OCT-1, version 4.1) was performed by a single operator using circular scans concentric with the optic disc with scan diameters of 3.40 mm, 4.50 mm, and 1.75 x vertical disc diameter (VDD). For each scan diameter, mean peripapillary RNFL thickness was calculated. Statistical analysis comprised repeated-measurements analysis and Pearson correlation. RESULTS: Mean peripapillary RNFL thickness did not correlate with SE for the 3.40-mm (r = -0.11, P = 0.22), 4.50-mm (r = -0.103, P = 0.24), or 1.75xVDD (r = -0.08, P = 0.36) OCT scan diameters. Neither did mean peripapillary RNFL thickness correlate with axial length for the 3.40-mm (r = -0.04, P = 0.62), 4.50-mm (r = 0.03, P=0.75), or 1.75xVDD (r = -0.02, P = 0.78) scan diameters. Mean peripapillary RNFL thicknesses for the 3.40-mm, 4.50-mm, and 1.75xVDD scans were 101.1+/-8.2 microm (95% confidence interval [CI], 99.4-102.8), 78.9+/-8.2 microm (95% CI, 77.5-80.3), and 97.5+/-10.9 microm (95% CI, 95.6-99.4), respectively. CONCLUSIONS: Mean peripapillary RNFL thickness did not vary with myopic SE or axial length for any OCT scan diameter investigated. Retinal NFL thickness measurements may be a useful parameter to assess and monitor glaucoma damage in myopic subjects.

Detection of narrow angles and established angle closure in Chinese residents of Singapore: potential screening tests.

PURPOSE: To assess the performance of peripheral and central anterior chamber depth (ACD) measurements, and autorefraction, in identifying Chinese people with occludable drainage angles or established primary angle closure. DESIGN: Population-based cross-sectional analysis. METHODS: Subjects aged 40 years and older were drawn from a representative sample of Chinese Singaporean residents. Limbal chamber depth (LCD) was estimated and central ACD was measured using optical pachymetry and ultrasound. An autorefraction was taken for all subjects. Angle width and the presence of peripheral anterior synechiae were determined by gonioscopy. Receiver operating characteristic curves were generated to show the performance of these tests in detecting occludable angles. RESULTS: A total of 1090 subjects were examined. The prevalence of occludable angles was 6.5%. LCD measurement performed best in detecting occludable angles (area under the curve [AUC] 0.904, 95% confidence interval [CI] 0.870, 0.937). Optical pachymetry and ultrasound measurement of ACD performed less well (AUC 0.859 and 0.810, respectively), and autorefraction performed poorly in detecting occludable angles (AUC 0.632). LCD also gave the best performance in detecting primary angle closure (AUC 0.782, 95% CI 0.727, 0.837). CONCLUSIONS: Limbal LCD estimation outperforms other methods of measuring ACD as a screening tool for the detection of occludable drainage angles in the Chinese population of Singapore.