Configuration of the drainage angle, intraocular pressure, and optic disc cupping in subjects with chronic angle-closure glaucoma

Twenty-Four-Hour Intraocular Pressure in Chronic Primary Angle-Closure Disease

PRCIS

Primary angle closure and primary angle closure glaucoma may exhibit normal intraocular pressure. Twenty-four-hour intraocular pressure fluctuation is highest in primary angle closure glaucoma. The degree of peripheral anterior synechiae was associated with a 24-hour intraocular pressure pattern in primary angle-closure disease without laser iridotomy.

PURPOSE

The purpose of this study was to study 24-hour intraocular pressure (IOP) patterns in eyes with chronic primary angle-closure disease and evaluate associations between peripheral anterior synechiae (PAS) and 24-hour IOP pattern.

PATIENTS AND METHODS

In this prospective cohort study, 59 eyes of 35 Asian patients with chronic primary angle-closure disease underwent complete ocular examinations at Ramathibodi Hospital, Mahidol University. Twenty-four-hour IOP records were obtained using Goldmann applanation tonometry at 2-hour intervals. Peak, mean, and trough 24-hour IOP values and 24-hour IOP fluctuation (difference between peak and trough values) were compared among groups. None of the participants received any treatment before complete data collection.

RESULTS

Even univariable analysis demonstrated a significant difference in peak, mean, and trough IOP and 24-hour IOP fluctuation between the 3 groups; the magnitude of trough IOP was not higher than 21 mmHg in all groups. In multivariable analysis, PAC and PACG eyes showed significantly higher peak IOP ( P =0.020 and 0.006, respectively) and 24-hour IOP fluctuation ( P =0.048 and 0.001, respectively) compared with PACS eyes. In comparison between combined PACS and PAC eyes versus PACG eyes, PACG eyes revealed significantly higher 24-hour IOP fluctuation. The degree of PAS was associated with peak and mean IOP values and with 24-hour IOP fluctuation in PAC and PACG eyes.

CONCLUSIONS

Twenty-four-hour IOP fluctuation was highest in PACG eyes. Although PAC and PACG eyes showed higher peak IOP and 24-hour IOP fluctuation values, compared with PACS eyes, trough IOP in PAC and PACG eyes were mostly below 21 mmHg. In addition, the degree of PAS was associated with a 24-hour IOP pattern in either PAC or PACG eyes.

Assessment of Iris Trabecular Contact in Eyes with Gonioscopic Angle-Closure

PURPOSE

To investigate the extent of iris trabecular contact (ITC) measured by anterior segment OCT (AS-OCT) and its association with primary angle-closure (PAC) and PAC glaucoma (PACG) in eyes with gonioscopic angle-closure and to determine the diagnostic performance of ITC for detection of gonioscopic angle-closure.

DESIGN

Multicenter, prospective study.

PARTICIPANTS

A total of 119 healthy participants with gonioscopic open-angle and 170 patients with gonioscopic angle-closure (94 with PAC suspect and 76 with PAC/PACG) were included.

METHODS

One eye of each subject was randomly selected for AS-OCT imaging. Angle-opening distance (AOD500) and trabecular iris space area (TISA500) were measured every 10° for 360°. Two criteria of ITC500 were examined: (1) AOD500 = 0 mm and (2) TISA500 = 0 mm². The association between the extent of ITC500 and PAC/PACG in eyes with gonioscopic angle-closure was analyzed with logistic regression analysis.

MAIN OUTCOME MEASURES

Sensitivity and specificity of ITC500 for detection of gonioscopic angle-closure; odds ratio (OR) of PAC/PACG.

RESULTS

The sensitivity of ITC500 ≥ 10° for detection of gonioscopic angle-closure ranged from 82.4% (AOD500 = 0 mm) to 84.7% (TISA500 = 0 mm²), and the specificity was 85.7% (for both AOD500 = 0 mm and TISA500 = 0 mm²). The extent of ITC500 determined by AS-OCT, not cumulative gonioscopy score (i.e., the sum of the modified Shaffer grades over 4 quadrants), was associated with the odds of PAC/PACG in eyes with gonioscopic angle-closure; the odds of PAC/PACG increased by 5% for every 10° increase in ITC500 (OR, 1.051, 95% confidence interval [CI], 1.022-1.080 for AOD500 = 0 mm; OR, 1.049, 95% CI, 1.022-1.078 for TISA500 = 0 mm²). Axial length and anterior chamber depth were not associated with PAC/PACG in eyes with gonioscopic angle-closure (P ≥ 0.574).

CONCLUSIONS

A greater extent of ITC measured by AS-OCT, not angle-closure determined by gonioscopy, was associated with a greater odds of PAC/PACG in eyes with gonioscopic angle-closure.

Identification of Peripheral Anterior Synechia by Corneal Deformation Using Air-Puff Dynamic Anterior Segment Optical Coherence Tomography

Indentation gonioscopy is commonly used in the clinic to evaluate peripheral anterior synechia (PAS) of angle closure glaucoma (ACG). The examination requires contacting with the cornea, resulting in an uncomfortable feeling for patients, and it only provides qualitative outcomes which may be affected by subjective judgment of the clinicians. Previous studies had reported to identify the presence of PAS by measuring the changes of morphological parameters of the anterior chamber angle (ACA) under the pupillary light reflex, by anterior segment optical coherence tomography (AS-OCT). However, this method was invalid for some subjects who had low sensitiveness to light. This article describes an air-puff dynamic anterior segment optical coherence tomography (DAS-OCT) system that can evaluate the presence of PAS in a non-contact approach. The peripheral cornea is deformed by an air puff jetted from the DAS-OCT, causing a transfer of force to the ACA, just as how indentation gonioscopy works. The dynamic changes of the ACA before and after the air puff are recorded by OCT. Ten eyes of normal subjects were enrolled in this study to validate the repeatability and availability of the measurements. Then, ten samples of the ACA from five subjects with ACG were recruited and were assigned into two groups, the non PAS group (NPAS) and PAS group, according to the results of gonioscopy. The ACA structural parameters including the angle opening distance at 750 μm to the scleral spur (AOD750) and the trabecular-iris space area at 750 μm anterior to the scleral spur (TISA750) were then calculated automatically by a custom-written algorithm. The intraclass correlation coefficient (ICC) of measured parameters was all above 0.85 for normal subjects, exhibiting good repeatability. For patients, both parameters showed significant differences between the two groups after the air puff, while no differences were observed before the air puff. AOD750dif and TISA750dif between two groups showed more significant differences, indicating that they could be used as indicators to identify the presence of PAS. In conclusion, the DAS-OCT system proposed in this study is demonstrated effective to identify the presence of PAS by measuring the changes of the ACA via a noncontact approach. It shows great potential for applications in guidance for diagnosis of angle closure glaucoma.

Angle closure extent, anterior segment dimensions and intraocular pressure

AIM

To investigate the association between the extent of iridotrabecular contact and other quantitative anterior segment dimensions measured by swept-source optical coherence tomography (SS-OCT; CASIA SS-1000, Tomey, Nagoya, Japan) with intraocular pressure (IOP).

METHODS

Cross-sectional study. All subjects who were ≥50 years with no history of glaucoma, ocular surgery or trauma, underwent SS-OCT imaging (eight equally spaced radial scans), Goldman applanation tonometry and gonioscopy on the same day. We measured iridotrabecular contact (ITC) index and area, total volume of trabeculo-iris space area and angle opening distance at 500 and 750 from the scleral spur (TISA 500 and 750, AOD 500 and 750, respectively), anterior chamber depth (ACD), volume, area and width, pupil diameter, lens vault and iris volume.Their relationship with IOP (dependent variable) was assessed by locally weighted scatterplot smoothing (Lowess) regression with change-point analysis and generalised additive models adjusted for confounders.

RESULTS

2027 right eyes of mostly Chinese Singaporeans (90%) were analysed. ITC index above a threshold of ~60% (95% CI 34% to 92%) was significantly associated with higher IOP. Independent of the extent of ITC, ACD was also significantly associated with higher IOP below a threshold of 2.5 mm (95% CI 2.33 mm to 2.71 mm). Greater ITC index and shallower ACD had a joint association with IOP. A model including ACD and ITC index was more predictive of IOP than a model considering these variables separately, particularly for women with gonioscopically closed angles (R² 52.7%, p<0.05).

CONCLUSIONS

The extent of angle closure and the ACD below a certain threshold had a significant joint association with IOP. These parameters, as biometrical surrogates of mechanical obstruction of the aqueous outflow, may jointly contribute to elevated IOP, particularly in women with gonioscopic angle closure.

Identification of peripheral anterior synechia with anterior segment optical coherence tomography

PURPOSE

To generate a model that evaluates the presence and extent of peripheral anterior synechia (PAS) based on anterior segment optical coherence tomography (AS-OCT).

METHODS

The extent of PAS involvement in the eyes of patients with angle closure was assessed by indentation gonioscopy, and the part of non-PAS and PAS were assigned into two groups (NPAS and PAS). Anterior chamber angles were then imaged by AS-OCT with light-emitting diode (LED) irradiation directly into the pupils, leading to pupillary constriction and increasing anterior chamber angle width. Parameters including the angle opening distance at 750 μm anterior to the scleral spur (AOD750) and trabecular-iris space area at 750 μm anterior to the scleral spur (TISA750) were then obtained. The differences before and after LED irradiation of AOD750 and TISA750 were calculated and used to generate a PAS model based on binary logistic regression. Validation data were then tested.

RESULTS

A total of 258 AS-OCT images in 14 eyes were assigned to the modeling data, and 120 were assigned to the validation data. There were no differences in AOD750 and TISA750 in the dark between NPAS and PAS (P_AOD750 = 0.258, P_TISA750 = 0.486), whereas after LED light exposure, TISA750_light was larger in NPAS than in PAS (P = 0.047). The light-dark differences of both parameters showed significant differences between the two groups (P_AOD750dif = 0.019, P_TISA750dif < 0.001). The area under the curve of the model performance was 0.841, and the overall correct rate was 80.8% based on the validation data.

CONCLUSIONS

The present study demonstrates that the AS-OCT-based PAS model could be useful in the identifying of the presence of synechial angle closure and evaluating the extent of PAS in a single eye.

Association Between Anterior Chamber Angle and Corneal Endothelial Cell Density in Chronic Angle Closure

Purpose

To study the association between corneal endothelial cell density (ECD) and degree of anterior chamber angle (ACA) opening in eyes with chronic angle closure glaucoma.

Methods

The study was conducted at JEC Eye Hospitals in Indonesia. Treatment-naïve patients aged ≥40 years with IOP >21 mmHg and peripheral anterior chamber depth (ACD) grade 2 or less by Van Herick's technique were recruited. Trabecular iris angle (TIA; degree) was measured using anterior segment optical coherence tomography (AS-OCT) and classified as: grade 1 ≤10°, grade 2 11-20°, and grade 3 >20°. Noncontact specular microscopy was performed, and the following corneal parameters were obtained:ECD (cells/mm²), coefficient of variation (CV; μm²/cell), percentage of hexagonal cells, and central corneal thickness (CCT; μm).

Results

A total of 52 eyes from 52 subjects were recruited (16 grade 1 TIA, 24 grade 2 TIA, and 12 grade 3 TIA). Presenting IOP was not significantly different between groups. The median central corneal ECD was 2684.5 (1433-2934), 2587.0 (1902-3103), and 2441.0 (1659-3005) cells/mm² in grade 1, 2, and 3 TIA, respectively, with no significant differences across the groups (P = 0.67). The CV was lowest in grade 3 TIA (36.4 ± 7.2 μm2/cell), and highest in grade 1 TIA (38.3 ± 9.6 μm2/cell), but the differences were not significant (P = 0.74). Likewise, the percentage of hexagonality and CCT was not significantly different. TIA was not correlated with IOP but was modestly correlated with age.

Conclusion

The corneal ECD and morphological characteristics such as CV and hexagonality were not significantly different across various TIA grading in chronic angle closure. This may reflect the lack of chronic and gradual IOP insult on corneal endothelial parameters as TIA did not show direct effect towards IOP.

Ten-Year Clinical Outcomes of Acute Primary Angle Closure Randomized to Receive Early Phacoemulsification Versus Laser Peripheral Iridotomy

PURPOSE

To compare the 10-year clinical outcomes of eyes with acute primary angle closure (APAC) randomized to receive either early phacoemulsification or laser peripheral iridotomy (LPI).

METHODS

Sixty-two APAC patients, who underwent either early phacoemulsification (phaco group) or laser peripheral iridotomy (LPI group) in a previous randomized controlled trial, were invited for assessment 10 years after the interventions. The results of the 2 groups were compared.

RESULTS

Forty of 62 patients (64.5%; 19 in phaco group and 21 from LPI group) were examined. None of them underwent additional glaucoma procedure but 15 (71.4%) patients in the LPI group received lens extraction before this assessment. The mean follow-up duration was 10.7±0.7 years. The phaco group used less medication (0.16±0.37 vs. 0.76±1.09 bottle per eye, P=0.028), had less extensive anterior synechiae (120.0±116.12 vs. 244.3±139.8 degree, P=0.010), and greater mean Shaffer gonioscopy grading (1.79±0.84 vs. 1.40±0.87; P=0.021) than the LPI group. Five eyes had persistent intraocular pressure elevation of >21 mm Hg in 2 consecutive visits and 4 eyes had blindness (best-corrected visual acuity worse than 6/60 and/or central visual field of <20 degree) in the LPI group, compared with none in the phaco group (P=0.022 and 0.045, respectively). There was no significant difference in the mean intraocular pressure, best-corrected visual acuity, and the number of eyes with visual field progression.

CONCLUSION

At 10 years, APAC eyes that underwent early phacoemulsification required less medication, less peripheral anterior synechiae, lower incidence of intraocular pressure elevation and a lower incidence of blindness compared with APAC eyes that underwent initial LPI.

A Minimally Invasive Experimental Model of Acute Ocular Hypertension with Acute Angle Closure Characteristics

Purpose

To describe a minimally invasive experimental model of acute ocular hypertension (OHT) with characteristics of acute angle closure (AAC).

Methods

Adult C57/Bl6 mice (n = 31) were subjected to OHT in one eye using a modified circumlimbal suture technique that elevated intraocular pressure (IOP) for 30 minutes. Contralateral un-operated eyes served as controls. IOP, anterior segment optical coherence tomography, and fundus fluorescein angiography (FFA) were performed. The positive scotopic threshold response (pSTR) and a-wave and b-wave amplitudes were also evaluated. Retinal tissues were immunostained for the retinal ganglion cell (RGC) marker RBPMS and the glial marker GFAP.

Results

OHT eyes developed shallower anterior chambers and dilated pupils. FFA showed focal leakage in 32.2% of OHT eyes, but in none of the control eyes. pSTR was significantly reduced at week 1 in OHT eyes compared to control eyes (57.3 ± 7.2 µV vs. 106.9 ± 24.8 µV; P < 0.05), but a- and b-waves were unaffected. GFAP was upregulated in OHT eyes but not in control eyes or eyes that had been sutured without OHT. RGC density was reduced in OHT eyes after 4 weeks (3857 ± 143.8) vs. control eyes (4469 ± 176.0) (P < 0.05).

Conclusions

Our minimally invasive model resulted in acute OHT with characteristics of AAC in the absence of non-OHT-related neuroinflammatory changes arising from ocular injury alone.

Translational Relevance

This model provides a valuable approach to studying specific characteristics of a severe blinding disease in an experimental setting. Focal areas of ischemia were demonstrated, consistent with clinical studies of acute angle closure patients elsewhere, which may indicate the need for further research into how this could affect visual outcome in these patients.

Case Report: Iridocorneal Endothelial Syndrome Progression Documented by Anterior Segment Optical Coherence Tomography

SIGNIFICANCE

Iridocorneal endothelial (ICE) syndrome is characterized by a difficult-to-see membrane of ectopic corneal endothelial cells, called an ICE membrane. This report demonstrates that ICE membranes are detectable by anterior segment optical coherence tomography (AS-OCT) and highlights the benefits of using AS-OCT in ICE syndrome.

PURPOSE

A case of ICE syndrome is reported to highlight the utility of AS-OCT in the characterization and diagnosis of the disease.

CASE REPORT

A 65-year-old African American man was diagnosed as having the Chandler variant of ICE syndrome of the left eye. He was treated topically for corneal edema. Anterior segment optical coherence tomography and anterior segment photography were used to aid in the diagnosis and document an ICE membrane and multiple peripheral anterior synechiae. Further examinations chronicled the progression of a peripheral anterior synechia. At first, only iridocorneal touch (sparing the trabecular meshwork) was present, but later, full apposition to the trabecular meshwork developed. The patient was diagnosed as having pre-perimetric glaucoma in the left eye and is being treated topically to reduce his intraocular pressure. The right eye remains unremarkable.

CONCLUSIONS

Anterior segment optical coherence tomography can support the diagnosis of ICE syndrome by visualizing ICE membranes and differentiating between true peripheral anterior synechiae and iridocorneal touch that does not block the trabecular meshwork. Chronicling ICE membranes longitudinally with AS-OCT will enhance understanding of disease progression. By correlating membranes features (such as location and extent) and patient outcomes, AS-OCT-based ICE membrane classifications can be developed to improve the management and prognosis of ICE syndrome.

Correlation between Intraocular Pressure and Angle Configuration Measured by OCT: The Chinese American Eye Study

PURPOSE

To characterize the relationship between angle configuration measured by anterior segment optical coherence tomography (AS-OCT) and intraocular pressure (IOP).

DESIGN

Cross-sectional study.

PARTICIPANTS

Subjects aged 50 years or older were identified from the Chinese American Eye Study (CHES), a population-based epidemiological study in Los Angeles, CA.

METHODS

Each subject underwent a complete ocular exam including Goldmann applanation tonometry, gonioscopy, and AS-OCT imaging. Four AS-OCT images were analyzed per eye and parameters describing angle configuration were measured, including angle opening distance (AOD), angle recess area (ARA), trabecular iris space area (TISA), trabecular iris angle (TIA), and scleral spur angle (SSA). The relationship between AS-OCT measurements and IOP was assessed using locally-weighted scatterplot smoothing (LOWESS) regression and change-point analyses.

MAIN OUTCOME MEASURES

Correlation between AS-OCT measurements and IOP.

RESULTS

702 eyes (382 closed angle and 320 open angle) from 555 subjects were analyzed. Mean IOP for angle closure eyes was 16.3 ± 3.9 mmHg and open angle eyes was 15.3 ± 2.7 mmHg. Mean IOP increased as AS-OCT measurements decreased for all parameters except TIA750. Once measurement values dropped below parameter-specific threshold values, AS-OCT measurements and IOP were significantly correlated (p < 0.05) for AOD500 (r = -0.416), AOD750 (r = -0.213), ARA500 (r = -0.669), ARA750 (r = -0.680), TISA500 (r = -0.655), TISA750 (r = -0.641), SSA500 (r = -0.538), and SSA750 (r = -0.208). There was no correlation between AS-OCT measurements and IOP in open angle eyes (p > 0.40).

CONCLUSIONS

There is an anatomic threshold for angle configuration below which IOP is strongly related to the degree of angle closure. This finding suggests reconsideration of current definitions of angle closure and may be relevant for developing new OCT-based methods to identify patients at higher risk for elevated IOP and glaucoma.

The Effect of Cumulative Dissipated Energy on Changes in Intraocular Pressure After Uncomplicated Cataract Surgery by Phacoemulsification

PURPOSE

To investigate the association between ultrasound energy, expressed as cumulative dissipated energy (CDE), and changes in intraocular pressure (IOP) after uncomplicated cataract surgery by phacoemulsification.

METHODS

In this prospective study, nonglaucomatous subjects underwent cataract surgery by phacoemulsification. IOP was compared by clustered linear regression at 4 separate time-points: preoperative, 1 day, 1 month, and 3 months after cataract surgery. Changes in the IOP were evaluated as a function of CDE using univariate and multivariate clustered linear regression models, which adjusted for sex, ethnicity, age, axial length, spherical equivalent, mean preoperative Shaffer gonioscopy grade of all 4 quadrants, cataract grade, preoperative IOP, central corneal thickness, and use of both eyes in the same subject.

RESULTS

One hundred sixty-one eyes (89 Asian, 49 white, 12 African, and 11 Hispanic) from 116 nonglaucomatous subjects were analyzed. The 161 eyes included 81 right and 80 left eyes. The 89 Asian eyes included 46 Chinese, 35 Filipino, and 8 Vietnamese. Preoperative IOP was 14.9±3.2 mm Hg. Postoperative IOP significantly increased to 16.0±4.9 mm Hg at 1 day (P=0.037) and decreased to 12.4±3.1 and 12.3±3.0 mm Hg at 1 and 3 months, respectively (both P<0.0001). IOP changes at 1 day, 1 month, and 3 months did not demonstrate significant associations with CDE measurements in either univariate or multivariate clustered linear regression analyses (all P>0.05).

CONCLUSIONS

The amount of ultrasound energy delivered to the eye during phacoemulsification, expressed as CDE, was not associated with postoperative changes in IOP.

Anterior Chamber Angle Assessment by Anterior-segment Optical Coherence Tomography After Phacoemulsification With or Without Goniosynechialysis in Patients With Primary Angle Closure Glaucoma

PURPOSE

To evaluate changes of anterior chamber angle (ACA) by anterior-segment optical coherence tomography (AS-OCT) in patients with primary angle closure glaucoma (PACG) following phacoemulsification (phaco) with or without goniosynechialysis (GSL).

METHODS

Patients with PACG recruited into 2 randomized controlled trials comparing phaco-GSL versus phaco were pooled for analysis. Images of ACA were obtained by AS-OCT before surgery, and at 1 and 2 weeks, and 1, 3, and 6 months after surgery. The following parameters were analyzed: angle opening distance (AOD) at 500 and 750 μm from the scleral spur, trabecular-iris space area (TISA) at 500 and 750 μm, angle recess area (ARA) at 500 and 750 μm, and scleral spur angle (SSA).

RESULTS

All parameters of ACA increased significantly after phaco-GSL (P<0.001), whereas no increase occurred in the phaco group. Negatively significant correlations were found in ΔAOD500 (P<0.05), ΔARA750 (P<0.05), ΔTISA500 (P<0.05), and ΔTISA750 (P<0.05) at 1, 3, and 6 months, and ΔSSA (P<0.05) at 3 and 6 months after phaco-GSL against Δ intraocular pressure (IOP). In the phaco-GSL group, 23 of 23 eyes had IOP<21 mm Hg without any antiglaucoma medication postoperatively. In the phaco group, 12 of 20 eyes (60%) had IOP<21 mm Hg without medication, 8 of 20 eyes required medication with IOP<21 mm Hg (15%) and uncontrollable IOP (25%) after surgery.

CONCLUSIONS

On AS-OCT evaluation, ACA in eyes with PACG opened and widened significantly after phaco-GSL in our study. It is suggested that ΔAOD500, ΔARA750, ΔTISA500, ΔTISA750, and ΔSSA would provide valuable information to estimate the effectiveness of phaco-GSL.

Association Between Trabecular Meshwork Anteroposterior Length and Anterior Chamber Angle Width

PURPOSE

To investigate the association between trabecular meshwork anteroposterior length and anterior chamber angle width in nonglaucomatous subjects.

DESIGN

Prospective, cross-sectional study.

METHODS

Time-domain and spectral-domain anterior segment optical coherence tomography images for 561 eyes from 366 nonglaucomatous subjects were analyzed to determine trabecular meshwork anteroposterior length and 3 anterior chamber angle width parameters measured at different distances from the scleral spur: angle opening distance at 250 μm (AOD250), 500 μm (AOD500), and 750 μm (AOD750) from the scleral spur; trabecular-iris space area at 500 μm (TISA500) and 750 μm (TISA750) from the scleral spur; angle recess area at 750 μm (ARA750) from the scleral spur. Univariable and multivariable linear mixed-effect regression models, the latter adjusting for age, sex, ethnicity, axial length, and the use of both eyes in the same subject, were used to evaluate the association between trabecular meshwork anteroposterior length and anterior chamber angle width parameters.

RESULTS

Mean trabecular meshwork anteroposterior length was 824.86 ± 181.77 μm. Univariate regression analyses showed a significant positive association between trabecular meshwork anteroposterior length and all anterior chamber angle width parameters: AOD250 (P < .001; β = 335.13), AOD500 (P < .001; β = 271.84), AOD750 (P < .001; β = 202.56), TISA500 (P < .001; β = 780.78), TISA750 (P < .001; β = 449.17), ARA750 (P < .001; β = 381.39). Multivariate regression analyses showed a significant positive association between trabecular meshwork anteroposterior length and all anterior chamber angle width parameters: AOD250 (P = .005; β = 294.02), AOD500 (P = .036; β = 172.94), AOD750 (P = .049; β = 125.58), TISA500 (P = .004; β = 611.51), TISA750 (P = .011; β = 333.96), ARA750 (P < .0001; β = 309.12).

CONCLUSIONS

Wider anterior chamber angle is associated with greater trabecular meshwork anteroposterior length.

Optical Coherence Tomography Imaging for Glaucoma - Today and Tomorrow

Digital imaging technologies for glaucoma diagnostics have evolved rapidly over the recent years. From time-domain optical coherence tomography (OCT) to spectral-domain and swept-source OCTs, the application of OCT for analysis of the anterior chamber angle and the optic nerve head (ONH) is expanding. The second-generation anterior segment swept-source OCT is able to image the configuration of the anterior chamber angle in 3 dimensions in less than 1 second and perform 360-degree analysis of the anterior chamber angle width for detection of angle closure. The morphology, density, and dimensions of the crystalline lens in relation to the anterior chamber can now be examined from the anterior corneal surface to the posterior lens surface, facilitating the investigation of the involvement of the crystalline lens in primary angle closure. Spectral-domain and swept-source OCTs have improved the measurement reliability of the lamina cribrosa and the neuroretinal rim configurations. Studying the deformation of the lamina cribrosa and ONH surfaces is relevant to decipher the mechanisms of ONH damage in the development and progression of glaucoma. Software and algorithms for automatic analysis of the anterior chamber angle dimensions and deformation of the ONH and lamina cribrosa surfaces are required to process large volumetric data sets, and they are under active development. It is expected that new imaging technologies will improve the detection and risk assessment of angle-closure and open-angle glaucomas.

Comparison of ocular biometry between eyes with chronic primary angle-closure glaucoma and their fellow eyes with primary angle-closure or primary angle-closure suspect

PURPOSE

To compare the eye with chronic primary angle-closure glaucoma (CPACG) with its fellow eye without glaucoma damage and to determine the biometric differences that may predispose to development of CPACG.

METHODS

Consecutive patients diagnosed with CPACG in 1 eye and primary angle-closure (PAC)/primary angle-closure suspected (PACS) in the fellow eye were recruited. The biometric parameters of both the eyes were measured by A-scan ultrasonic biometry and ultrasound biomicroscopy. Comparisons of visual function, baseline intraocular pressure (IOP), and the biometric measurements were made.

RESULTS

Forty-one patients were recruited. Eyes with CPACG had worse visual function, higher baseline IOP, and larger cup-to-disc ratio than their fellow eyes with PAC/PACS (P<0.001). Eyes with CPACG had shallower anterior chamber depths, smaller anterior chamber angles, thinner irises, and longer iris-ciliary process distances than their fellow eyes with PAC/PACS (P<0.05). There were no significant differences in terms of lens thicknesses, axial lengths, lens vault, and trabecular-ciliary process distances.

CONCLUSIONS

Lens thickness, lens location, and axial length do not appear to play a significant role in the progression from PAC/PACS to CPACG. A thin and anterior iris bowing may be related to the progression from PAC/PACS to CPACG.

Meta-analysis of randomized controlled trials comparing latanoprost with other glaucoma medications in chronic angle-closure glaucoma

PURPOSE

To evaluate the efficacy and safety of latanoprost compared with other glaucoma medications in the treatment of chronic angle-closure glaucoma (CACG) and to provide the basis for clinical medication.

METHODS

Major literature databases were searched for randomized controlled trials (RCT) involving latanoprost among patients with CACG. Primary outcome measures were absolute changes in intraocular pressure (IOP) and incidence of ocular adverse events. Statistical analyses included the calculation of standardized mean difference (SMD) and relative risk (RR). The statistical analysis was performed using STATA version 12.0 software.

RESULTS

Ten RCT involving 1096 patients were included in this meta-analysis. Analysis showed that latanoprost was not significantly different from other glaucoma medications in reducing IOP (SMD = 0.29, 95% confidence interval [CI] -0.02 to 0.59, p=0.069). Further subgroup analysis revealed that latanoprost was superior compared with timolol (SMD = 0.64, 95% CI 0.46 to 0.82, p&lt;0.001) and marginally inferior to travoprost and bimatoprost (SMD = -0.19, 95% CI -0.35 to -0.02, p = 0.026). As for conjunctival hyperemia, latanoprost caused a higher proportion than timolol (RR = 2.36, 95% CI 1.27 to 4.37, p = 0.007). However, latanoprost was associated with lower incidence of conjunctival hyperemia (RR = 0.42, 95% CI 0.30 to 0.59, p&lt;0.001), and with fewer occurrence of other ocular side effects (excluding conjunctival hyperemia) than travoprost and bimatoprost (RR = 0.61, 95% CI 0.48 to 0.78, p&lt;0.001).

CONCLUSIONS

Travoprost and bimatoprost are superior in IOP control than latanoprost, but latanoprost is better tolerated in patients with CACG.

A prospective comparison of chronic primary angle-closure glaucoma versus primary open-angle glaucoma in Singapore

INTRODUCTION

To describe the optic disc, visual field and ocular characteristics of a consecutive cohort of Asian patients with chronic primary angle-closure glaucoma (CPACG), and compare them with those having primary open-angle glaucoma (POAG).

METHODS

In a prospective comparative case series of new patients with POAG or CPACG in Singapore, all patients underwent visual acuity assessment, slit-lamp examination, tonometry, gonioscopy, refraction, Heidelberg Retina Tomograph (HRT) and Humphrey visual field (HVF) assessment.

RESULTS

98 patients were enrolled (POAG n = 48; CPACG n = 50). CPACG patients were significantly older (66.5 ± 9.2 years vs. 64.1 ± 13.5 years; p = 0.027) and mostly female (p = 0.004). CPACG eyes had significantly higher intraocular pressure (26.9 ± 6.9 mmHg vs. 24.5 ± 3.3 mmHg; p = 0.03), shorter axial length (22.89 ± 0.97 mm vs. 24.26 ± 1.79 mm; p < 0.001) and shallower anterior chamber depth (2.60 ± 0.25 mm vs. 3.16 ± 0.48 mm; p < 0.001). HVF mean deviation or pattern standard deviation (PSD) did not differ significantly between POAG and CPACG eyes, but the latter had a lower PSD for a given mean deviation. HRT parameters between the two groups were not significantly different.

CONCLUSION

In this study, CPACG eyes had significantly higher presenting intraocular pressure than POAG eyes, but there were no significant differences in optic disc topography. A majority of the patients in both groups had moderate field defects at the time of presentation, followed by severe and then mild defects. The field loss in CPACG eyes was more diffuse than that in POAG eyes.

Anterior segment imaging in glaucoma

Anterior segment imaging allows objective assessment of the anterior segment of the eye, particularly the anterior chamber angle. Both qualitative and quantitative analyses are possible and aid in detecting and managing closed-angle and open-angle mechanisms in various forms of glaucoma. This review focuses primarily on anterior segment optical coherence tomography and ultrasound biomicroscopy, with emphasis on principles of technology, commercially available devices, and clinical applications in glaucoma with potential advantages and disadvantages of each technology.

Anterior chamber angle imaging with swept-source optical coherence tomography: measuring peripheral anterior synechia in glaucoma

OBJECTIVE

To investigate the use of swept-source optical coherence tomography (OCT) for measuring the area and degree of peripheral anterior synechia (PAS) involvement in patients with angle-closure glaucoma.

DESIGN

Cross-sectional study.

PARTICIPANTS

Twenty-three eyes with PAS (detected by indentation gonioscopy) from 20 patients with angle-closure glaucoma (20 eyes had primary angle-closure glaucoma and 3 eyes had angle-closure glaucoma secondary to chronic anterior uveitis [n = 2] and Axenfeld-Rieger syndrome [n = 1]).

METHODS

The anterior chamber angles were evaluated with indentation gonioscopy and imaged by swept-source OCT (Casia OCT, Tomey, Nagoya, Japan) in room light and in the dark using the "angle analysis" protocol, which was composed of 128 radial B-scans each with 512 A-scans (16-mm scan length). The area and degree of PAS involvement were measured in each eye after manual detection of the scleral spur and the anterior irido-angle adhesion by 2 masked observers. The interobserver variability of the PAS measurements was calculated.

MAIN OUTCOME MEASURES

The agreement of PAS assessment by gonioscopy and OCT, the area and the degree of PAS involvement, and the intraclass correlation coefficient (ICC) of interobserver PAS measurements.

RESULTS

The area of PAS (mean ± standard deviation) was 20.8 ± 16.9 mm(2) (range, 3.9-74.9 mm(2)), and the degree of PAS involvement was 186.5 ± 79.9 degrees (range, 42-314 degrees). There was no difference in the area of PAS (P = 0.90) and the degree of PAS involvement (P = 0.95) between images obtained in room light and in the dark. The interobserver ICCs were 0.99 (95% confidence interval [CI], 0.98-1.00) for the area of PAS and 0.99 (95% CI, 0.97-1.00) for the degree of PAS involvement. There was good agreement of PAS assessment between gonioscopy and OCT images (kappa = 0.79; 95% CI, 0.67-0.91).

CONCLUSIONS

Swept-source OCT allows visualization and reproducible measurements of the area and degree of PAS involvement, providing a new paradigm for evaluation of PAS progression and risk assessment for development of angle-closure glaucoma.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Efficacy of goniosynechialysis for advanced chronic angle-closure glaucoma

Purpose:

To evaluate the intraocular pressure (IOP)-lowering efficacy of goniosynechialysis (GSL) for advanced chronic angle-closure glaucoma (CACG) using a simplified slit-lamp technique.

Patients and methods:

Patients with CACG with one severely affected eye with best-corrected visual acuity below 20/200 and a mildly or functionally unaffected fellow eye were enrolled in this study. All patients underwent ophthalmologic examinations including measurement of visual acuity, best-corrected visual acuity, and IOP; biomicroscopy; specular microscopy; fundus examination; and gonioscopy followed by anterior chamber paracentesis and GSL for nasal peripheral anterior synechiae in the eye with severe CACG.

Results:

Thirty patients (18 men, 12 women) were identified as having CACG with an initial mean IOP of 47.1 ± 6.7 mmHg (range 39–61 mmHg) in the severely affected eye. One week after GSL, the mean IOP of the treated eyes decreased to 19.3 ± 2.8 mmHg (range 14–26 mmHg) without antiglaucoma medication (average decrease 27.7 ± 6.5 mmHg; range 16–41 mmHg), which was significant (P < 0.00001) compared with baseline. After an average follow-up period of 36.6 ± 1.0 months (range 35–38 months), the mean IOP stabilized at 17.4 ± 2.2 mmHg (range 12–21 mmHg). The nasal angle recess did not close again in any one of the patients during the follow-up period. The average significant (P < 0.00001) decrease in corneal endothelial cell density in the treated eyes was 260 ± 183 cells/mm² (range 191–328 cells/mm²).

Conclusions:

Anterior chamber paracentesis and GSL lowers IOP in advanced CACG, though it may lead to mild corneal endothelial cell loss.

The role of anterior segment optical coherence tomography in glaucoma

The anterior segment optical coherence tomography provides an objective method to assess the anterior segment of the eye, including the anatomy of the anterior chamber angle. This technology allows both qualitative and quantitative analyses of the angle and has shown potential in detecting and managing angle-closure glaucoma. In addition, it has a role in identifying pathology in some forms of secondary open-angle glaucoma and postsurgical management of glaucoma. Limitations of this technology include its cost and inability to visualize well structures posterior to the iris, such as the ciliary body. This paper focuses on potential benefits and limitations of anterior segment optical coherence tomography when compared with conventional gonioscopy and ultrasound biomicroscopy. Various clinical entities will be described to discuss its potential role in glaucoma practice.

Comparison of optic nerve head topography and retinal nerve fiber layer in eyes with narrow angles versus eyes from a normal open angle cohort - a pilot study

PURPOSE

To compare the optic nerve head (ONH) and retinal nerve fiber layer (RNFL) in eyes with narrow angles and normal intraocular pressure (IOP) to normal control eyes.

MATERIALS AND METHODS

A total of 70 eyes of 52 subjects with narrow angles and 40 eyes of 34 normal subjects were enrolled. Narrow angle eyes were defined as the following: (i) the pigmented trabecular meshwork was not visible for ≥ 180° on gonioscopy, (ii) untreated IOP ≤ 21 mmHg, (iii) no peripheral anterior synechiae (PAS) was observed, and (iv) optic discs were without glaucomatous changes, defined as neuroretinal rim thinning, focal notching, disc hemorrhages, or focal RNFL defects. ONH and peripapillary RNFL imaging were obtained with Heidelberg Retina Tomograph (HRT II) and Fourier-domain optical coherence tomography (RTVue OCT).

RESULTS

No significant difference was found in mean age between the two groups (p = 0.06), but the narrow angle group had significantly more women (p = 0.04). The narrow angle group had significantly higher IOP and smaller mean angle width (both p < 0.001). Vertical cup-to-disc ratio (VCDR) was significantly larger in the narrow angle group (p = 0.02). In visual field (VF) results, the mean deviation (MD) was significantly lower and pattern standard deviation (PSD) was significantly higher in the narrow angle group (both p < 0.001). After adjusting for disc area, the RNFL thickness of the inferior-temporal region was significantly thinner in the narrow angle group (135 ± 21.7 µm) compared with normal group (149 ± 22.1 µm, p < 0.01). This finding remained significant after Bonferroni correction for multiple comparisons. Smaller angle width was a significant predictor of RNFL thinning in the inferior-temporal region (p < 0.001).

CONCLUSION

These data suggest that eyes with narrow angles may develop glaucomatous optic nerve damage in the absence of IOP elevation during office hours.

Angle imaging: advances and challenges

Primary angle closure glaucoma (PACG) is a major form of glaucoma in large populous countries in East and South Asia. The high visual morbidity from PACG is related to the destructive nature of the asymptomatic form of the disease. Early detection of anatomically narrow angles is important and the subsequent prevention of visual loss from PACG depends on an accurate assessment of the anterior chamber angle (ACA). This review paper discusses the advantages and limitations of newer ACA imaging technologies, namely ultrasound biomicroscopy, Scheimpflug photography, anterior segment optical coherence tomography and EyeCam, highlighting the current clinical evidence comparing these devices with each other and with clinical dynamic indentation gonioscopy, the current reference standard.

Acute primary angle closure attack does not cause an increased cup-to-disc ratio

PURPOSE

To determine if an increased cup-to-disc ratio (CDR) and retinal nerve fiber layer (RNFL) loss occur after acute primary angle closure (APAC).

DESIGN

Prospective, observational case series.

PARTICIPANTS

Twenty participants with unilateral APAC provided 20 affected eyes and 20 fellow eyes (controls) for analysis.

METHODS

After initial presentation, participants attended 3 further assessments over a 12-month period (visit 2, within 2 weeks; visit 3, 2-3 months; and visit 4, 6-12 months), in which they underwent the following investigations: Heidelberg Retinal Tomography (Heidelberg Engineering, Dossenheim, Germany), optical coherence tomography of the RNFL and macula, and automated perimetry.

MAIN OUTCOME MEASURES

Cup-to-disc ratio, optic cup area, neuroretinal rim area, RNFL thickness, macular thickness, and volume.

RESULTS

There was no change from visits 2 to 4 in CDR (0.46 ± 0.17 vs. 0.47 ± 0.20; P = 0.94), neuroretinal rim area (1.64 ± 0.55 vs. 1.64 ± 0.57; P = 0.96), or other optic nerve head parameters analyzed in eyes with APAC. The mean overall RNFL thickness decreased from 106.6 ± 17.9 μm to 92.9 ± 18.3 μm between visits 2 and 3 (P<0.01) in affected eyes. The superior quadrant RNFL thickness decreased from 134.8 ± 25.9 μm to 113 ± 25.7 μm (P<0.01), and the inferior quadrant RNFL thickness decreased from 139.1 ± 28.4 μm to 115.6 ± 24.9 μm (P<0.01). There was no significant change in macular thickness or volume.

CONCLUSIONS

This study demonstrated that an increase in CDR does not occur after APAC that is treated promptly, although RNFL loss does occur.

Simvastatin and disease stabilization in normal tension glaucoma: a cohort study

PURPOSE

To investigate whether simvastatin use is associated with visual field (VF) stabilization in patients with normal tension glaucoma (NTG).

DESIGN

Prospective cohort study (ClinicalTrials.gov Identifier: NCT00321386).

PARTICIPANTS

A total of 256 eyes from 256 Chinese subjects with NTG.

METHODS

Patients were followed up at 4-month intervals for 36 months for VF progression per Anderson's criteria. Clinical parameters were checked for association with progression in multivariate analysis.

MAIN OUTCOME MEASURES

The primary outcome was the association between simvastatin use and VF progression.

RESULTS

Thirty-one patients (12.1%) were taking simvastatin (statin+), and 225 patients (87.9%) were not taking simvastatin (statin-). Baseline age, gender, untreated intraocular pressure, VF indices, vertical cup-to-disc ratio, and central corneal thickness (CCT) were comparable between the 2 groups. There were significantly more patients with a history of hypercholesterolemia, systemic hypertension, and ischemic heart disease in the statin+ group. A total of 121 patients (47.3%) showed evidence of VF progression (mean rate of mean deviation loss was -0.30 decibel per year) during the 36 months of follow-up. Simvastatin use was among 8 of 121 patients (6.6%) who progressed compared with 23 of 135 patients (17.0%) who did not progress (P = 0.011). Logistic regression revealed that history of disc hemorrhage (relative risk [RR] 3.26; 95% confidence interval [CI], 1.21-8.76; P = 0.019), history of cerebrovascular accidents (RR 2.28; 95% CI, 1.03-5.06; P = 0.043), and baseline age (per 10 years older; RR 1.38; 95% CI, 1.08-1.76; P = 0.009) were significant risk factors for VF progression, whereas simvastatin use conferred a protective effect (RR 0.36; 95% CI, 0.14-0.91; P = 0.030).

CONCLUSIONS

Simvastatin use may be associated with VF stabilization in patients with NTG. A larger scale randomized controlled trial and cost-effectiveness analyses seem warranted.

Diurnal intraocular pressure fluctuation and associated risk factors in eyes with angle closure

OBJECTIVE

To investigate diurnal intraocular pressure (IOP) fluctuation in eyes with angle closure in comparison with normal subjects and to look for associated risk factors for IOP fluctuation.

DESIGN

Prospective, cross-sectional study.

PARTICIPANTS

Ninety-eight eyes of 98 Asian subjects with angle closure (consisting of 32 primary angle-closure suspects [PACS], 34 subjects with primary angle closure [PAC], and 32 subjects with primary angle-closure glaucoma [PACG]) and 21 eyes of 21 normal control subjects.

METHODS

All angle-closure subjects were enrolled after laser peripheral iridotomy but before commencement of any medical or surgical treatment. Ophthalmic examination, including dynamic gonioscopy and automated perimetry, were performed, and diurnal IOP measurements were obtained using noncontact air-puff tonometry at hourly intervals between 8:00 am and 5:00 pm. Mean diurnal IOP, peak diurnal IOP, trough IOP, and IOP fluctuation (peak IOP-trough IOP) were compared between groups. Multiple linear regression analysis was performed to study the association of IOP fluctuation with clinical variables such as age, extent of peripheral anterior synechiae (PAS), central corneal thickness, vertical cup-to-disc ratio, and pattern standard deviation (PSD) on automated perimetry.

MAIN OUTCOME MEASURES

Mean diurnal IOP, peak IOP, and IOP fluctuation.

RESULTS

Most subjects were Chinese (89.1%) and female (61.3%). Intraocular pressure fluctuation was significantly higher in PACG (5.4+/-2.4 mmHg) and PAC (4.5+/-2.3 mmHg) subjects compared with PACS subjects (3.7+/-1.2 mmHg) and normal controls (3.8+/-1.1 mmHg; P = 0.005), with highest IOP found in the early morning. The combined PACG and PAC group had more than twice the risk (odds ratio, 2.38; 95% confidence interval, 1.1-5.1; P = 0.025) of having IOP fluctuation of more than 3 mmHg compared with the combined PACS and normal group. Extent of PAS (Pearson's correlation coefficient, r = 0.37; P = 0.0001) and visual field PSD (r = 0.34; P = 0.0002) were found to be associated with greater IOP fluctuation.

CONCLUSIONS

The PACG and PAC eyes showed diurnal IOP fluctuation of 4 to 5 mmHg, and this fluctuation was higher than in PACS subjects and normal controls. The degree of PAS and visual field loss were associated with IOP fluctuation in PAC and PACG eyes.

Current Understanding of the Treatment and Outcome of Acute Primary Angle Closure Glaucoma: An Asian Perspective

Introduction: Primary angle-closure glaucoma (PACG) is a major cause of blindness among Asians. A better understanding of the disease will improve the treatment and outcome of this condition. Methods: A literature review of all recent publications on PACG was carried out. Articles were retrieved using a key word search of MEDLINE, PubMed and Science Citation Index databases. Results: Following laser peripheral iritodomy for acute angle-closure, Asians were found to have a higher tendency to develop a subsequent rise in intraocular pressure compared to Caucasians. Furthermore, the extent and severity of visual field damage was more severe in Asians than Caucasians, particularly in eyes that presented insidiously with chronic PACG. Prophylactic laser iridotomy in the contralateral eye was found to be highly effective in preventing acute angle-closure attacks. Conclusion: PACG is more difficult to manage and is associated with more severe long-term visual morbidity in Asians than Caucasians. Regular follow-up of patients with PACG is important for the early detection of progression of the disease and visual field deterioration.

Peripheral anterior synechiae and ultrasound biomicroscopic parameters in angle-closure glaucoma suspects

PURPOSE

To investigate the correlation between peripheral anterior synechia (PAS) and the quantitative anterior chamber angle parameters measured by ultrasound microscopy (UBM) in angle-closure glaucoma suspect (ACGS) eyes.

METHODS

Eyes were defined ACGS as having occludable angles and intraocular pressure less than 21 mm Hg without glaucomatous optic nerve head. The gonioscopic criteria for ACGS were the trabecular meshwork invisible in 3 or more quadrants of the entire angle and the angular width less than 20 degrees by Shaffer classification. Twenty-seven eyes of 20 patients underwent anterior chamber angle and ciliary body imaging with UBM. Angle opening distance (AOD(500)), angle recess area (ARA), trabecular-ciliary process distance (TCPD) and trabecular-iris angle (TIA) were measured from the UBM images at each quadrant.

RESULTS

The AOD(500), ARA, and TIA were not significantly different between the eyes with PAS (9 eyes) and without PAS (18 eyes) at each quadrant. However, the TCPD was significantly shorter in the superior quadrant when compared with the eyes without PAS (mean: 405.3+/-70.9 microm vs 536.4+/-140.5 microm) (p<0.05).

CONCLUSIONS

The results suggest that the shorter distance from trabecular meshwork to ciliary body or the anterior placement of ciliary process may play a role in the development of PAS in ACGS eyes.

Long Ciliary Processes With no Ciliary Sulcus and Appositional Angle Closure Assessed by Ultrasound Biomicroscopy

PURPOSE

Nonpupil block mechanisms and appositional angle closure after laser iridotomy (LI) have been reported as common findings in Asians. We evaluated the presence of these findings in a cohort of Brazilian patients using ultrasound biomicroscopy (UBM).

METHODS

This observational case-control study included 22 open angle eyes and 31 eyes with occludable angles on gonioscopy (defined by 2 examiners). UBM radial scans through a typical ciliary process were obtained in both light and dark conditions, at 6 and 12-o'clock positions. Long ciliary processes with no ciliary sulcus were determined on the basis of a reference line drawn perpendicular to the iris plane passing through a point located 750 mum from scleral spur. Trabecular ciliary processes distance was measured on 6-o'clock UBM images.

RESULTS

After LI, 52% of occludable angle eyes had appositional angle closure in both 6 and 12-o'clock UBM images. We also observed this finding in 14% and 23% of the control eyes (in 6 and 12-o'clock UBM images, respectively). A long ciliary process with no ciliary sulcus was observed in 61% of occludable angle eyes, and also in 32% of control eyes (6-o'clock UBM images). Control eyes had longer trabecular ciliary processes distance than occludable angle eyes (P<0.001).

CONCLUSIONS

The UBM finding of long ciliary processes associated with the absence of ciliary sulcus is not necessarily related to an anterior positioning of the ciliary processes. Whether UBM appositional angle closure after LI is associated with further angle closure process and/or poor intra-ocular pressure control remains to be evaluated.

Distribution and characteristics of peripheral anterior synechiae in primary angle-closure glaucoma

Purpose

To evaluate the characteristics of peripheral anterior synechiae (PAS) in primary angle-closure glaucoma (PACG).

Methods

We reviewed the charts of 155 patients (244 eyes) with PACG. We divided these patients into one of four clinical subtypes: acute angle-closure glaucoma (ACG), chronic ACG, angle-closure hypertension, and ACG suspect. The prevalence, extent, and location of PAS were evaluated according to PACG subtypes. Correlation analysis was used to evaluate relationships between the highest IOP level without treatment and the extent of PAS.

Results

The average degree of angle-closure with PAS was 14.6±9.1 in eyes that were classified as ACG suspect, 83.8±48.3 in angle closure hypertension, 140.5±31.3 in acute ACG, and 180.3±31.9 in chronic ACG (ANOVA test, P<0.05). PAS was most frequently found in the superior part of the eye, especially from 12 to 1 o' clock. The incidence of broad PAS (PAS over 30 degrees in width) was highest in superior part, but the medium and narrow PAS (PAS limited to within 30 degrees in width) was distributed throughout all 12 sectors relatively equally. Prior to a laser iridotomy (LI) and other medical treatments, a positive correlation was found between the highest IOP (intraocular pressure) levels and the extent of PAS in chronic ACG (r=0.423, P<0.0001). However, statistically significant relationships were not found between the highest IOP levels before treatment and the extent of PAS in any of the other clinical subtypes.

Conclusions

Our results suggest that acute and chronic ACG patients are most likely to have a greater extent of PAS than patients in the angle closure hypertension or are ACG suspect subtypes. PAS may be narrower in earlier stages and broader in later stages. PAS was also found most frequently in the superior part of the eye. The extent of synechial closure of the angle may play a role in raising IOP levels in later stages of the disease rather than early on.

Comparison of Glaucomatous Optic Nerve Damage in Primary Angle-Closure Glaucoma with and without Acute Attack

PURPOSE

To compare the glaucomatous optic nerve damage in primary angle-closure glaucoma (PACG) with acute attack (acute PACG; AACG) and PACG without acute attack (chronic PACG; CACG).

METHODS

The study subjects were 84 normal individuals, 130 AACG patients, and 86 CACG patients. Color optic disc photographs were evaluated for the presence or absence of 10 qualitative signs to differentiate between normal and glaucomatous optic discs.

RESULTS

Abnormally shaped rim width (alteration of ISN'T rule), bared circumlinear vessel, vessel bayonetting, rim width narrower than the temporal sector, and zone beta (nasal and superotemporal sectors) were detected more frequently in the CACG group than in the AACG group (P<0.05). The most accurate qualitative sign was abnormally shaped rim width in both groups. The specificity and sensitivity of abnormally shaped rim width were 71.4% and 60.8% for AACG, and 71.4% and 81.4% for CACG, respectively.

CONCLUSIONS

The optic disc damage is greater in CACG than in AACG.