Ramanjit Sihota

Comparison of anterior segment optical coherence tomography and ultrasound biomicroscopy for assessment of the anterior segment

PURPOSE: To compare anterior segment parameters using quantitative imaging by anterior segment optical coherence tomography (AS‐OCT) and ultrasound biomicroscopy (UBM). SETTING: Tertiary‐care glaucoma research center. METHODS: Sixty‐three eyes of 63 subjects had anterior segment evaluation by AS‐OCT (Visante‐Zeiss) and UBM (Paradigm). Central corneal thickness (CCT), anterior chamber depth (ACD) (measured from the central corneal endothelium to the anterior lens capsule), and the peripheral iridocorneal angles (temporal and nasal) were assessed and compared. RESULTS: There was an excellent correlation between AS‐OCT and UBM measurements for the nasal angle (r = 0.84; P<.0001), temporal angle (r = 0.86; P<.0001), ACD (r = 0.97; P<.0001), and CCT (r = 0.91; P<.0001). There was no significant difference (paired t test) between the mean ACD, CCT, and angle parameters measured by AS‐OCT or UBM. The mean values of the parameters measured by AS‐OCT and UBM were, respectively, as follows: nasal angle, 26.25 degrees ± 11.0 (SD) and 28.27 ± 11.3 degrees (P = .3); temporal angle, 25.1 ± 11.4 degrees and 28.3 ± 13.5 degrees (P = .15); ACD, 2.85 ± 0.5 mm and 2.78 ± 0.5 mm (P = .2); and CCT, 512 ± 46 μm and 502 ± 46 μm (P = .25). The AS‐OCT images showed sharper definition of the scleral spur than the UBM images. CONCLUSION: Anterior segment optical coherence tomography and UBM can both be used for anterior segment measurements and yielded comparable results.

Ocular parameters in the subgroups of angle closure glaucoma.

Purpose: This study was conducted to compare anatomical parameters, thought to be responsible for causing angle closure glaucoma (ACG), among eyes having acute, subacute or chronic ACG.

Ultrasound biomicroscopy in the subtypes of primary angle closure glaucoma.

Purpose:To evaluate the anterior segment parameters in the subtypes of primary angle closure glaucoma (PACG) using ultrasound biomicroscopy. Methods:Five groups, each comprising 30 consecutive patients, diagnosed to have subacute PACG, acute PACG, chronic PACG, primary open angle glaucoma (POAG), and healthy controls were included in the present study. All patients underwent slit-lamp biomicroscopy, direct ophthalmoscopy, 90D fundus examination, gonioscopy, applanation tonometry, visual field testing, A-scan biometry, and ultrasound biomicroscopy (UBM). The anterior segment parameters recorded included: trabecular-iris angle, angle opening distance, trabecular ciliary process distance, and the iris thickness among other parameters. Results:On ultrasound biomicroscopy the trabecular iris angle of control and POAG groups was more than all the subtypes of PACG (P < 0.001). The trabecular iris angle of subacute PACG (P < 0.001) and chronic PACG (P = 0.003) was more than acute PACG. Angle opening distance of controls and POAG group was significantly more than acute PACG and chronic PACG (P < 0.001). The trabecular ciliary process distance of POAG group and controls was more than subacute PACG, acute PACG, and chronic PACG. The trabecular ciliary process distance of subacute PACG (P < 0.001) and chronic PACG (P < 0.001) was more than acute PACG. Eyes with acute PACG had the least iris thickness at the three different positions tested. There was a positive correlation between the anterior chamber angle (trabecular iris angle) and the following parameters: trabecular ciliary process distance, angle opening distance, anterior chamber depth, and the axial length (r2 = 0.57). Conclusion:Eyes with primary angle closure glaucoma have a thinner iris with a shorter trabecular iris angle, angle opening distance, and trabecular ciliary process distance. The eyes with acute primary angle closure glaucoma have the narrowest angle recess.

Utility values among glaucoma patients: an impact on the quality of life

Aim: To ascertain utility values and associated quality of life with different severity and duration of glaucoma among Indian patients. Methods: Utility values of 105 consecutive patients with primary glaucoma of at least 12 months’ duration were evaluated in a cross sectional study. Utility values were ascertained in five groups using both the time-trade off and standard gamble methods: group 1 (best corrected visual acuity in the better eye of 6/9 or better), group 2 (best corrected visual acuity in the better eye of 6/18 to 6/12), group 3 (best corrected visual acuity in the better eye of 6/36 to6/24), group 4 (best corrected visual acuity in the better eye of 3/60 to 6/60), and group 5 (best corrected visual acuity in the better eye of 3/60 or worse). Results: The mean utility value for the glaucoma group as a whole was 0.64 (SD 0.69; 95% confidence interval (CI), 0.58 to 0.70) with the time-trade off method and 0.86 (SD 1.00; 95% CI, 0.81 to 0.90) with the standard gamble method for a gamble of death and 0.97 (SD 1.00; 95% CI, 0.94 to 0.99) for a gamble of blindness. The mean utility results by the time-trade off method were as follows: group 1 = 0.66, group 2 = 0.66, group 3 = 0.62, group 4 = 0.55, and group 5 = 0.61. The utility value was much lower (0.46) in those with no formal education or only primary education compared to those with postgraduate education (0.75) (p = 0.038). Those patients with glaucoma of less than 5 years’ duration had a utility score of 0.62 while those with glaucoma for more than 10 years had a score of 0.74 (p = 0.40). Conclusions: Visual acuity loss occurring secondary to glaucoma is associated with a substantial decrease in patient utility value (and quality of life) in a developing country like India. The utility value is directly dependent on the degree of visual acuity loss associated with the disease and educational status and not on the duration of disease, the number of medications, or the visual field indices.

Variables Affecting Test-retest Variability Of Heidelberg Retina Tomograph Ii Stereometric Parameters

PurposeTo study the test-retest variability of stereometric parameters on the Heidelberg Retina Tomograph II, a new clinical instrument for glaucoma management. MethodsIn a cross-sectional study of 24 consecutive cases of glaucoma and 26 healthy subjects, Heidelberg Retina Tomograph II stereometric parameters from five consecutive images were obtained for one randomly selected eye of each subject. Test-retest variability was studied using three different statistical methods (coefficient of variance, intraclass correlation coefficient, and Cronbach &agr;). The effect of age, diagnosis, linear cup/disc ratio, visual acuity, and refractive error on test-retest variability on HRT II was analyzed. The repeatability of Moorfields regression analysis and the baseline variability in the progression analysis software was also studied. ResultsUsing coefficient of variance, intraclass correlation coefficient, and Cronbach &agr;, the test-retest variability was found to be lowest for mean cup depth, cup area, cup/disc area ratio, vertical cup/disc ratio and rim/disc area ratio, in that order. Test-retest variability had a significant correlation with age (r = 0.33, P = 0.019) and visual acuity (r = −0.46, P = 0.005). Compared with eyes with astigmatism less than 1 D (mean coefficient of variance = 6.4 ± 4.9), the test-retest variability was higher (P = 0.044) in eyes with astigmatism more than 1D (mean coefficient of variance = 20.0 ± 22.6). Moorfields regression analysis was inconsistent in 52% cases. The average baseline change in progression analysis software was 0.076 ± 0.081. ConclusionThe test-retest variability of Heidelberg Retina Tomograph II stereometric parameters is comparable to that reported for the Heidelberg Retina Tomograph. Eyes with uncorrected astigmatism more than 1 D and poor visual acuity may have a higher variability of Heidelberg Retina Tomograph II stereometric parameters.

Post-penetrating keratoplasty glaucoma

To study the risk factors in the development of glaucoma following penetrating keratoplasty, we retrospectively analysed 190 eyes of 185 consecutive patients who had undergone surgery during 1990. The donor button was larger by 0.2 mm and 0.5 mm in phakia and aphakia/pseudophakia patients, respectively. Over a mean follow-up period of 14.5 months, 52 of the 190 eyes (27.4%) either developed glaucoma de novo or had worsening of preexisting glaucoma. Of these 52 eyes, 38 were managed medically and 14 required surgery. From our study, aphakia (37%), pseudophakia (24%), preexisting glaucoma (81.8%), and regrafting (43.18%) were found to be the significant risk factors in the development of glaucoma following penetrating keratoplasty.

Corneal endothelial status in the subtypes of primary angle closure glaucoma

Purpose: To study the corneal endothelium and pachymetry in eyes with different subtypes of primary angle closure glaucoma (PACG), as compared to controls.

Long-term evaluation of trabeculectomy in primary open angle glaucoma and chronic primary angle closure glaucoma in an Asian population

Purpose: A retrospective cohort study was undertaken to evaluate and compare the long‐term results of trabeculectomy in primary open angle glaucoma (POAG) and chronic primary angle closure glaucoma (CPACG) in an Asian population.

Evaluation of Oxidative Stress Markers in Aqueous Humor of Primary Open Angle Glaucoma and Primary Angle Closure Glaucoma Patients

Abstract Purpose: The present study was designed to determine the levels of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) and non-enzymatic antioxidants (vitamins C and E) in aqueous humor of primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG) patients. Materials and Methods: In this study, aqueous humor of POAG (n = 30) and PACG (n = 30) patients was obtained. For control, aqueous humor of 30 age-matched cataract patients (n = 30) was collected. Activities of antioxidant enzymes and non-enzymatic antioxidants levels were measured spectrophotometrically. Results: A significant increase in superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities was found in aqueous humor of POAG and PACG patients as compared to cataract patients (p < 0.001). No significant changes were observed in catalase activity. The levels of vitamins C and E were significantly lower in the aqueous humor of POAG and PACG as compared to cataract patients (p < 0.001). Conclusion: These results suggest that a significant increase in oxidative stress may play a role in the pathogenesis of POAG and PACG. Determination of oxidative stress in aqueous humor may help in understanding the course of this disease, and oxidative damage might be a relevant target for both prevention and therapy.

Comparison of ultrasound biomicroscopic parameters after laser iridotomy in eyes with primary angle closure and primary angle closure glaucoma

PurposeTo study changes in anterior segment morphology after laser peripheral iridotomy (LPI) in primary angle closure (PAC) and primary angle closure glaucoma (PACG) using ultrasound biomicroscopy (UBM).MethodsNinety-three eyes of 93 patients underwent anterior segment evaluation including gonioscopy, disc evaluation with + 90D lens, applanation intraocular pressure, and standard achromatic perimetry. UBM was performed before and 2 weeks after Nd:YAG LPI to measure the trabecular-iris angle (TIA), the angle-opening distance (AOD 250/500), and the central anterior chamber depth (ACD).ResultsThe superior TIA widened from a mean of 7.54±3.15 to 15.66±6.69° (P=0.0001), the inferior TIA increased from a mean of 9.0±4.7 to 15.9±6.8° (P=0.0001) after LPI in PAC. In PACG, the mean superior angle changed from 4.55±2.5 to 6.12±3.8° (P=0.4) and the inferior angle increased from 4.75±2.0 to 7.9±3.7° (P=0.1). The mean ACD increased from 2.19±0.36 to 2.30±0.36 mm in PAC group (P=0.0003), with no significant change seen in the PACG group (1.79±0.32 vs1.82±0.33 mm, P=0.13).ConclusionLPI leads to a widening of the anterior chamber angle and a deepening of the anterior chamber in eyes with PAC. It does not significantly change any anterior segment parameters in eyes with PACG.