Anterior Segment Imaging Predicts Incident Gonioscopic Angle Closure.

PURPOSE: To investigate the incidence of gonioscopic angle closure after 4 years in subjects with gonioscopically open angles but varying degrees of angle closure detected on anterior segment optical coherence tomography (AS OCT; Visante; Carl Zeiss Meditec, Dublin, CA) at baseline. DESIGN: Prospective, observational study. PARTICIPANTS: Three hundred forty-two subjects, mostly Chinese, 50 years of age or older, were recruited, of whom 65 were controls with open angles on gonioscopy and AS OCT at baseline, and 277 were cases with baseline open angles on gonioscopy but closed angles (1-4 quadrants) on AS OCT scans. METHODS: All subjects underwent gonioscopy and AS OCT at baseline (horizontal and vertical single scans) and after 4 years. The examiner performing gonioscopy was masked to the baseline and AS OCT data. Angle closure in a quadrant was defined as nonvisibility of the posterior trabecular meshwork by gonioscopy and visible iridotrabecular contact beyond the scleral spur in AS OCT scans. MAIN OUTCOME MEASURES: Gonioscopic angle closure in 2 or 3 quadrants after 4 years. RESULTS: There were no statistically significant differences in age, ethnicity, or gender between cases and controls. None of the control subjects demonstrated gonioscopic angle closure after 4 years. Forty-eight of the 277 subjects (17.3%; 95% confidence interval [CI], 12.8-23; P < 0.0001) with at least 1 quadrant of angle closure on AS OCT at baseline demonstrated gonioscopic angle closure in 2 or more quadrants, whereas 28 subjects (10.1%; 95% CI, 6.7-14.6; P < 0.004) demonstrated gonioscopic angle closure in 3 or more quadrants after 4 years. Individuals with more quadrants of angle closure on baseline AS OCT scans had a greater likelihood of gonioscopic angle closure developing after 4 years (P < 0.0001, chi-square test for trend for both definitions of angle closure). CONCLUSIONS: Anterior segment OCT imaging at baseline predicts incident gonioscopic angle closure after 4 years among subjects who have gonioscopically open angles and iridotrabecular contact on AS OCT at baseline.

Sectoral variations of iridocorneal angle width and iris volume in Chinese Singaporeans: a swept-source optical coherence tomography study.

PURPOSE: To assess variations in the iridocorneal angle width and iris volume in Chinese subjects using swept-source optical coherence tomography (SS-OCT). METHODS: Consecutive subjects, aged 40-80 years, with no previous ophthalmic problems were recruited from a population-based study of Chinese Singaporeans. All subjects underwent 360° SS-OCT (SS-1000 CASIA, Tomey Corporation, Nagoya, Japan) angle imaging and gonioscopy in one randomly selected eye in the dark. For each eye, 16 frames (11.25° apart) were selected for analysis from 128 cross-sectional images, and measurements of the trabecular iris space area 750 µm from the scleral spur (TISA750) and iris volume were made for each image. The measurements from four consecutive frames were further averaged as a sector of 45°. Sector-wise angle width and quadrant-wise iris volume were analyzed. RESULTS: Two hundred and twelve subjects (90 with closed-angles) were examined. The majority of the subjects were female (70.7 %) with mean age 61 (±8.9) years. The TISA750 (mm(2)) of superior [0.101 (0.09)], inferior [0.105 (0.09)], superior-nasal [0.111 (0.09)] and superior-temporal [0.117 (0.09)] sectors were smaller compared with other sectors (P < 0.05). The nasal iris volume (mm(3)) was the smallest compared with other quadrants for the entire cohort [nasal 8.18 (1.2) < inferior 9.13 (1.3) < temporal 9.16 (1.2) < superior 9.33 (1.3), P < 0.001], as well as for open- and closed-angle groups. CONCLUSIONS: The irido-corneal angle was narrower in the superior, inferior, superior-nasal and superior-temporal sectors compared with other sectors. Iris volume in the nasal quadrant was the smallest compared with the other quadrants.

Classification algorithms based on anterior segment optical coherence tomography measurements for detection of angle closure.

OBJECTIVE: A recent study found that a combination of 6 anterior segment optical coherence tomography (ASOCT) parameters (anterior chamber area, volume, and width [ACA, ACV, ACW], lens vault [LV], iris thickness at 750 µm from the scleral spur, and iris cross-sectional area) explain >80% of the variability in angle width. The aim of this study was to evaluate classification algorithms based on ASOCT measurements for the detection of gonioscopic angle closure. DESIGN: Cross-sectional study. PARTICIPANTS: We included 2047 subjects aged ≥50 years. METHODS: Participants underwent gonioscopy and ASOCT (Carl Zeiss Meditec, Dublin, CA). Customized software (Zhongshan Angle Assessment Program, Guangzhou, China) was used to measure ASOCT parameters in horizontal ASOCT scans. Six classification algorithms were considered (stepwise logistic regression with Akaike information criterion, Random Forest, multivariate adaptive regression splines, support vector machine, naïve Bayes' classification, and recursive partitioning). The ASOCT-derived parameters were incorporated to generate point and interval estimates of the area under the receiver operating characteristic (AUC) curves for these algorithms using 10-fold cross-validation as well as 50:50 training and validation. MAIN OUTCOME MEASURES: We assessed ASOCT measurements and angle closure. RESULTS: Data on 1368 subjects, including 295 (21.6%) subjects with gonioscopic angle closure were available for analysis. The mean (±standard deviation) age was 62.4±7.5 years and 54.8% were females. Angle closure subjects were older and had smaller ACW, ACA, and ACV; greater LV; and thicker irides (P<0.001 for all). For both, the 10-fold cross-validation and the 50:50 training and validation methods, stepwise logistic regression was the best algorithm for detecting eyes with gonioscopic angle closure with testing set AUC of 0.954 (95% confidence interval [CI], 0.942-0.966) and 0.962 (95% CI, 0.948-0.975) respectively, whereas recursive partitioning had relatively the poorest performance with testing set AUC 0.860 (95% CI, 0.790-0.930) and 0.905 (95% CI, 0.876-0.933), respectively. This algorithm performed similarly well (AUC, 0.957) in a second independent sample of 200 angle closure subjects and 302 normal controls. CONCLUSIONS: A classification algorithm based on stepwise logistic regression that used a combination of 6 parameters obtained from a single horizontal ASOCT scan identified subjects with gonioscopic angle closure>95% of the time. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Assessment of trabecular meshwork width using swept source optical coherence tomography.

PURPOSE: Measurements of the angle width by ultrasound biomicroscopy or anterior segment optical coherence tomography are usually performed 500 µm from the scleral spur, as the anterior part of trabecular meshwork (TM) is assumed to lie within this distance. The aim of this study was to measure TM width using swept source optical coherence tomography (SS-OCT, CASIA SS-1000, Tomey Corporation, Nagoya, Japan), and to investigate factors influencing this measurement. METHODS: Participants underwent gonioscopy and SS-OCT imaging in the dark. High-definition SS-OCT images were corrected for refractive distortion; and customized software (ImageJ; National Institutes of Health, Bethesda, MD, USA) was utilized to measure TM width (distance between the scleral spur and Schwalbe's line). Linear regression analysis was performed to assess the relationship between TM width with demographic and angle parameters. RESULTS: One hundred and forty eight Chinese subjects were analyzed. The majority was female (62.4 %); the mean age was 59.2 ± 8.68 years. Identification of the scleral spur and Schwalbe's line with SS-OCT was possible in 590 (99.7 %) and 585 angle quadrants (98.8 %) respectively. TM width was wider in the inferior and superior quadrants (mean 889 [SD 138] and 793 [136] µm), compared to the nasal and temporal quadrants (712 [137] and 724 [115] µm, P<0.001). There was a difference in average TM width between open (789 [100]) and closed angle eyes (753 [86]) (P=0.048). There was no significant association between TM width and angle parameters, laterality, or demographic factors. CONCLUSIONS: In SS-OCT HD images, the mean TM width varied from 710 to 890 µm in the different quadrants of the eye, and the inferior quadrant TM was the widest compared to other quadrants.

Quantitative iris parameters and association with narrow angles.

PURPOSE: 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. DESIGN: Cross-sectional, community-based study. PARTICIPANTS: We recruited 2047 subjects >50 years old without ophthalmic symptoms from a community clinic in Singapore. METHODS: 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. MAIN OUTCOME MEASURES: The association between iris parameters and narrow angles on gonioscopy. RESULTS: 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. CONCLUSIONS: 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. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Novel association of smaller anterior chamber width with angle closure in Singaporeans.

PURPOSE: To describe variations in anterior chamber width (ACW) and investigate its association with the presence of narrow angles. DESIGN: Cross-sectional study. PARTICIPANTS: 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. METHODS: 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. MAIN OUTCOME MEASURES: Anterior chamber width and narrow angles. RESULTS: 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). CONCLUSIONS: 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.

Optical coherence tomography of the retina and optic nerve - a review.

Optical coherence tomography (OCT) is a rapid non-contact method that allows in vivo imaging of the retina, optic nerve head and retinal nerve fibre layer (RNFL). Since its introduction in Ophthalmology approximately a decade ago, the use of this technology has disseminated into the clinical practice. OCT has proven to be a useful ancillary tool for assessing retinal diseases because of its capability to provide cross-sectional images of the retina, and also to perform quantitative analysis of retinal morphology. In glaucoma, the OCT represents one of the methods capable of documenting and analysing optic disc and RNFL morphology in attempt to diagnose and monitor glaucomatous optic neuropathy. Recently, the spectral domain OCT became available, a new technique that allowed major improvements particularly regarding image acquisition speed and image resolution. Future studies will address how these major technological advances will impact the use of the OCT in research and clinical practice.

Prevalence of plateau iris in primary angle closure suspects an ultrasound biomicroscopy study.

PURPOSE: To determine the prevalence of plateau iris in a cohort of primary angle closure suspects (PACSs) using ultrasound biomicroscopy (UBM). DESIGN: Cross-sectional observational study. PARTICIPANTS: Subjects over the age of 50 years diagnosed as PACSs. INTERVENTION: Subjects were randomized to undergo laser peripheral iridotomy (LPI) in one eye. Ultrasound biomicroscopy was performed before and a week after LPI. MAIN OUTCOME MEASURES: Ultrasound biomicroscopy images were qualitatively assessed using standardized criteria. Plateau iris was defined in a quadrant by the presence of an anteriorly directed ciliary body, an absent ciliary sulcus, a steep iris root from its point of insertion followed by a downward angulation from the corneoscleral wall, presence of a central flat iris plane, and irido-angle contact. At least 2 quadrants had to fulfil the above criteria for an eye to be defined as plateau iris. RESULTS: Two hundred five subjects were enrolled; UBM images of 167 subjects were available for analysis. Plateau iris was found in 54 of 167 (32.3%) PACS eyes after LPI. Quadrantwise analysis showed that 44 of 167 (26.3%) eyes had plateau iris in 1 quadrant, 36 (21.5%) in 2 quadrants, 16 (9.5%) in 3 quadrants, and 2 (1.2%) in all 4 quadrants. Plateau iris was most commonly observed in the superior and inferior quadrants. CONCLUSIONS: Using standardized UBM criteria, plateau iris was found in about a third of PACS eyes after LPI. Prospective longitudinal studies are required to determine the clinical significance of this finding for the management of PACSs.

Comparison of gonioscopy and anterior segment ocular coherence tomography in detecting angle closure in different quadrants of the anterior chamber angle.

PURPOSE: 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). DESIGN: Cross-sectional observational study. PARTICIPANTS: Five hundred two consecutive subjects more than 50 years of age with no previous ophthalmic problems recruited from a community clinic in Singapore. METHODS: 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. MAIN OUTCOME MEASURES: 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. RESULTS: 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. CONCLUSIONS: 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.

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

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.

Effect of glaucomatous damage on repeatability of confocal scanning laser ophthalmoscope, scanning laser polarimetry, and optical coherence tomography.

PURPOSE: To determine and compare the effect of the severity of glaucomatous damage on the repeatability of retinal nerve fiber layer (RNFL) thickness with GDx-VCC (variable corneal compensation) and StratusOCT (optical coherence tomography; both produced by Carl Zeiss Meditec, Inc., Dublin, CA), and optic nerve head (ONH) topography with HRT-II (retinal tomograph; Heidelberg Engineering GmbH, Heidelberg, Germany) and StratusOCT. METHODS: With each of these techniques, two measurements were obtained from 41 eyes of 41 control subjects and 98 glaucomatous eyes (37 patients with early, 29 with moderate, and 32 with severe field loss). To evaluate test-retest variability at each stage, limits of agreement (Bland-Altman plots) and repeatability coefficients (RCs) were obtained from pairs of measurements. Comparisons of within-subject variances were used to compare repeatability of GDx-VCC versus StratusOCT for global RNFL and HRT-II versus StratusOCT for global ONH topography. Effects from age, visual acuity, and lens status were also included in the analysis as covariates. RESULTS: Test-retest variability of RNFL using GDx-VCC and StratusOCT were consistent through all stages of disease severity. Repeatability results of GDx-VCC were better than those of StratusOCT, except in severe cases. Test-retest variability of ONH topography using HRT-II and StratusOCT increased with increasing disease severity for rim area, cup area, and cup-to-disc (C/D) area ratio. In contrast, vertical C/D ratio from HRT-II, and horizontal C/D ratio from StratusOCT showed stable test-retest variability through all stages. Regardless of disease severity, repeatability results of HRT-II were better than those of StratusOCT. CONCLUSIONS: GDx-VCC and HRT-II showed better repeatability than StratusOCT. Although test-retest variability increased with disease severity for rim area, the variability for vertical C/D ratio (HRTII) and global RNFL (GDx-VCC) was stable across disease severity. These parameters, rather than rim area, may be more useful in detection of progression in patients with glaucoma who have more advanced field loss.

Prevalence of glaucoma in a South brazilian population: Projeto Glaucoma.

PURPOSE: To assess the prevalence of glaucoma in a South Brazilian population. METHODS: Subjects older than 40 years underwent a screening examination that included a medical interview, slit lamp examination, tonometry, and fundoscopy. Those with suspected glaucoma (based on optic disc appearance and/or intraocular pressure) underwent a comprehensive ophthalmic evaluation during the definitive examination. Glaucoma was diagnosed based on the International Society of Geographical and Epidemiologic Ophthalmology classification. RESULTS: A total of 1636 subjects were examined (76.5% participation rate); 71% of the study population self-reported their race as white and 24% as nonwhite (most black and mixed-black/white). Glaucoma was found in 56 subjects (crude prevalence of all glaucoma: 3.4%; 95% CI, 2.5-4.3), primary open-angle glaucoma (POAG) was found in 40 (2.4%; 95% CI, 1.7-3.2), and primary angle-closure glaucoma (PACG) in 12 (0.7%; 95% CI, 0.3-1.1). Six (12%) subjects with primary glaucoma had a previous diagnosis of the disease. Nonwhite persons had a higher prevalence rate of POAG than did white participants, although this difference was not significant (3.8% vs. 2.1%, respectively, P = 0.11). Unilateral blindness due to primary glaucoma was observed in seven subjects (five POAG/2 PACG), and nonwhites had a higher rate of unilateral blindness than did whites (five versus two cases, respectively, P = 0.014). CONCLUSIONS: Compared to incidence in Hispanic and European populations, PACG was more common among South Brazilians, whereas the POAG rates were similar. The rate of undiagnosed glaucoma was almost 90%. The higher POAG prevalence in the population self-reported as nonwhite may affect the estimation of glaucoma in Brazil, as more than 40% of the population self-report their race as nonwhite.

Detecting visual function abnormalities using the Swedish interactive threshold algorithm and matrix perimetry in eyes with glaucomatous appearance of the optic disc.

OBJECTIVE: To compare the ability of 24-2 frequency-doubling perimetry (FDP-Matrix) with standard automated perimetry with the Swedish interactive threshold algorithm (SAP-SITA) in detection of visual function abnormalities in patients with glaucomatous-appearing optic discs (GAOD). METHODS: This observational case-control study included 80 patients with GAOD and 54 control subjects diagnosed by masked assessment of optic disc stereoscopic photographs. Abnormal visual function at SAP-SITA and FDP-Matrix testing required consistent abnormalities in 2 visual field examinations, determined using the glaucoma hemifield test outside 99% normal limits, pattern standard deviation outside 95% normal limits, or 3 contiguous points in the pattern deviation probability plot outside 95% normal limits (at least 1 P<1%) within the same hemifield. RESULTS: The FDP-Matrix and SAP-SITA detected abnormal visual function in 51% and 44%, respectively, of GAOD eyes (P = .26), and both perimetry techniques identified 11% of healthy eyes as abnormal. Agreement between FDP-Matrix and SAP-SITA was moderate (kappa = 0.49), as only 35% of GAOD eyes and 2% of healthy eyes had both visual field test results flagged as abnormal. CONCLUSIONS: The FDP-Matrix detected abnormal visual function in more eyes with GAOD than did SAP-SITA, although this difference was not significant. Each visual field test tended to identify different subsets of eyes with GAOD as abnormal. Combination of these perimetry techniques may improve the detection of visual function abnormalities in patients with glaucoma.

Comparison of diagnostic accuracy of Heidelberg Retina Tomograph II and Heidelberg Retina Tomograph 3 to discriminate glaucomatous and nonglaucomatous eyes.

PURPOSE: To compare the diagnostic accuracy of the Moorfields regression analysis (MRA), parameters, and glaucoma probability score (GPS) from Heidelberg Retinal Tomograph (HRT) 3 (Heidelberg Engineering, Heidelberg, Germany) with MRA and parameters from HRT II in discriminating glaucomatous and healthy eyes in subjects of African and European ancestry. DESIGN: Case-control institutional setting. METHODS: Seventy-eight glaucoma patients (44 of African ancestry, 34 of European ancestry) and 89 age-matched controls (46 of African ancestry, 33 European ancestry), defined by visual fields and self-reported race were included. Imaging was obtained with HRT II, and data were exported to a computer with the HRT 3 software using the same contour line. Area under the receiver operating characteristic (ROC) curves (AUCs), sensitivity, and specificity were evaluated for the entire group, the African ancestry group, and the European ancestry group separately. Mean disk area was compared between correctly and incorrectly diagnosed eyes by each technique. RESULTS: Disk, cup, and rim areas from HRT 3 were lower than HRT II (P < .0001). AUC (sensitivity at 95% specificity) was 0.85 (54%) for vertical cup-to-disk ratio (VCDR) HRT 3, 0.84 (45%) for VCDR HRT II, and 0.81 (44%) for GPS at the temporal sector. MRA HRT 3 showed greater sensitivity but lower specificity than HRT II for the entire group, the African ancestry group, and the European ancestry group. GPS classification had the lowest specificity. Glaucomatous eyes incorrectly classified by GPS had smaller mean disk area (P = .0002); control eyes incorrectly classified had greater mean disk area (P = .015). CONCLUSIONS: VCDR from HRT 3 showed higher sensitivity than HRT II and GPS for the entire group and for those of African ancestry and of European ancestry separately. Sensitivity of MRA improved in HRT 3 with some trade-off in specificity compared with MRA of HRT II. GPS yielded erroneous classification associated to optic disk size.

Predictive Value of the Water Drinking Test and the Risk of Glaucomatous Visual Field Progression.

PURPOSE: The purpose of this is to test the hypothesis the intraocular pressure (IOP) peaks during a stress test [the water drinking test (WDT)] can estimate the risk of future visual field progression in treated primary open-angle glaucoma (POAG) patients. PATIENTS AND METHODS: Design: Prospective, longitudinal study. SETTING: Clinical practice. STUDY POPULATION: Treated POAG patients whose IOP was ≤18 mm Hg and who had no IOP-lowering interventions between the date of the WDT and the last eligible visual field. INTERVENTION: At baseline examination, patients underwent the WDT and were then followed at regular intervals with office-based IOP measurements and visual field testing. MAIN OUTCOME MEASURE: Cox-proportional hazards survival analysis testing the predictive value of IOP peaks during the WDT versus IOP measurements during office hours on visual field progression. RESULTS: A total of 144 eyes of 96 patients with baseline visual field damage ranging from mild to severe followed for a mean of 28 months were analyzed. In the multivariable analysis adjusting for potential confounders, higher IOP peaks during the WDT were predictive of future visual field progression (hazard ratio=1.11; 95% confidence interval, 1.02 to 1.21; P=0.013). The average and peak IOP during office hours over the same follow-up period were not significantly associated with progression (P=0.651 and 0.569, respectively). CONCLUSIONS: IOP peaks detected with the WDT were predictive of future visual field progression in a treated POAG population. This stress test could be a useful tool for risk assessment in daily practice.

Association of Baseline Anterior Segment Parameters With the Development of Incident Gonioscopic Angle Closure.

IMPORTANCE: Baseline anterior segment imaging parameters associated with incident gonioscopic angle closure, to our knowledge, are unknown. OBJECTIVE: To identify baseline quantitative anterior segment optical coherence tomography parameters associated with the development of incident gonioscopic angle closure after 4 years among participants with gonioscopically open angles at baseline. DESIGN, SETTING, AND PARTICIPANTS: Three hundred forty-two participants aged 50 years or older were recruited to participate in this prospective, community-based observational study. Participants underwent gonioscopy and anterior segment optical coherence tomography imaging at baseline and after 4 years. Custom image analysis software was used to quantify anterior chamber parameters from anterior segment optical coherence tomography images. MAIN OUTCOMES AND MEASURES: Baseline anterior segment optical coherence tomography measurements among participants with gonioscopically open vs closed angles at follow-up. RESULTS: Of the 342 participants, 187 (55%) were women and 297 (87%) were Chinese. The response rate was 62.4%. Forty-nine participants (14.3%) developed gonioscopic angle closure after 4 years. The mean age (SD) at baseline of the 49 participants was 62.9 (8.0) years, 15 (30.6%) were men, and 43 (87.8%) were Chinese. These participants had a smaller baseline angle opening distance at 750 µm (AOD750) (0.15 mm; 95% CI, 0.12-0.18), trabecular iris surface area at 750 µm (0.07 mm2; 95% CI, 0.05-0.08), anterior chamber area (30 mm2; 95% CI, 2.27-3.74), and anterior chamber volume (24.32 mm2; 95% CI, 18.20-30.44) (all P < .001). Baseline iris curvature (-0.08; 95% CI, -0.12 to -0.04) and lens vault (LV) measurements (-0.29 mm; 95% CI, -0.37 to -0.21) were larger among these participants ( all P < .001). A model consisting of the LV and AOD750 measurements explained 38% of the variance in gonioscopic angle closure occurring at 4 years, with LV accounting for 28% of this variance. For every 0.1 mm increase in LV and 0.1 mm decrease in AOD750, the odds of developing gonioscopic angle closure was 1.29 (95% CI, 1.07-1.57) and 3.27 (95% CI, 1.87-5.69), respectively. In terms of per SD change in LV and AOD750, this translates to an odds ratio of 2.14 (95% CI, 2.48-12.34) and 5.53 (95% CI, 1.22-3.77), respectively. A baseline LV cut-off value of >0.56 mm had 64.6% sensitivity and 84.0% specificity for identifying participants who developed angle closure. CONCLUSIONS AND RELEVANCE: These findings suggest that smaller AOD750 and larger LV measurements are associated with the development of incident gonioscopic angle closure after 4 years among participants with gonioscopically open angles at baseline.

Comparison of the Intraocular Pressure Variation Provoked by Postural Change and by the Water Drinking Test in Primary Open-angle Glaucoma and Normal Patients.

PURPOSE: To evaluate the intraocular pressure (IOP) peak and variability detected by moving the body from sitting to supine position (postural test) and by the water drinking test (WDT) in normal and primary open-angle glaucoma (POAG) subjects. PATIENTS AND METHODS: Prospective, cross-sectional observational analysis of 14 eyes of 14 normal subjects and 31 eyes of 31 patients with POAG. All POAG subjects were under clinical therapy. IOP measurements were all performed on the same day. RESULTS: When the subjects moved to the supine position, there was an IOP increase of 1.36±1.34 and 2.84±2.21 mm Hg in the normal and POAG groups, respectively (P=0.011). During the WDT, mean IOP peak and fluctuation in the POAG group was 19.29±4.10 and 4.13±2.33 mm Hg, respectively. These levels were significantly higher in comparison with the normal group (16.50±3.76 and 2.71±0.99 mm Hg; P=0.018 and 0.022, respectively). The mean peak IOP observed in the WDT was significantly higher than the IOP in the supine position (19.29±4.10 vs. 17.32±4.66 mm Hg, P=0.013). The mean IOP increase during the WDT was also significantly higher when compared with the postural test (4.13±2.33 vs. 2.84±2.21 mm Hg, P=0.019). CONCLUSIONS: POAG eyes demonstrated a significant IOP increase when assuming the supine position and during the WDT. The IOP increase during the WDT was significantly higher than the IOP increase after postural test. Hence, the results of both tests are not interchangeable.

Changes in anterior segment dimensions over 4†years in a cohort of Singaporean subjects with open angles.

AIM: To evaluate quantitative changes in anterior segment optical coherence tomography (AS-OCT) parameters at 4 years in subjects with open angles on gonioscopy at baseline. METHODS: 339 gonioscopically open-angle subjects aged >50 years underwent AS-OCT imaging (Visante, Carl Zeiss Meditec, Dublin, California, USA) at baseline and at 4 years. Customised software was used to analyse images. Linear regression was performed to assess baseline predictors of change in mean trabecular iris space area (TISA). RESULTS: Of the 339 subjects, 204 (61%) had good images for analysis. The mean age at baseline was 60 (SD 6.42) years; 55.4% were women and 87.7% were Chinese. Overall, there was a decrease in anterior chamber depth (ACD), anterior chamber area (ACA), anterior chamber volume (ACV) and angle opening distance at 500/750 µm, TISA 500/750 µm, iris thickness at 2000 µm and iris area in both nasal and temporal quadrants (p<0.05) at 4 years. There was an increase in iris curvature (ICURV) and lens vault (LV) (p<0.05). With univariate analysis, shorter axial length (AxL), shallower ACD, greater LV, smaller ACA/ACV and larger mean ICURV at baseline were associated with less change in TISA750 at follow-up. On multivariate analysis, only baseline mean ICURV and shorter AxL were predictive of less change in TISA750 at 4 years. CONCLUSIONS: Angle width significantly decreased; ICURV and LV increased in subjects with gonioscopically open angles followed at 4 years. Eyes with shorter AxL and greater ICURV at baseline had lesser decrease in angle width.

Development of a score and probability estimate for detecting angle closure based on anterior segment optical coherence tomography.

PURPOSE: To develop a score along with an estimated probability of disease for detecting angle closure based on anterior segment optical coherence tomography (AS OCT) imaging. DESIGN: Cross-sectional study. METHODS: A total of 2047 subjects 50 years of age and older were recruited from a community polyclinic in Singapore. All subjects underwent standardized ocular examination including gonioscopy and imaging by AS OCT (Carl Zeiss Meditec). Customized software (Zhongshan Angle Assessment Program) was used to measure AS OCT parameters. Complete data were available for 1368 subjects. Data from the right eyes were used for analysis. A stepwise logistic regression model with Akaike information criterion was used to generate a score that then was converted to an estimated probability of the presence of gonioscopic angle closure, defined as the inability to visualize the posterior trabecular meshwork for at least 180 degrees on nonindentation gonioscopy. RESULTS: Of the 1368 subjects, 295 (21.6%) had gonioscopic angle closure. The angle closure score was calculated from the shifted linear combination of the AS OCT parameters. The score can be converted to an estimated probability of having angle closure using the relationship: estimated probability = e(score)/(1 + e(score)), where e is the natural exponential. The score performed well in a second independent sample of 178 angle-closure subjects and 301 normal controls, with an area under the receiver operating characteristic curve of 0.94. CONCLUSIONS: A score derived from a single AS OCT image, coupled with an estimated probability, provides an objective platform for detection of angle closure.