Ganesh B. Jonnadula

Effect of cataract extraction on Visual Field Index in glaucoma.

Purpose:To determine the effect of cataract on the Visual Field Index (VFI) in glaucoma patients. Methods:Reliable visual fields (VFs) of 53 patients (53 eyes) with primary glaucoma who underwent phacoemulsification either alone or combined with trabeculectomy were analyzed before and after surgery. All patients had VFs within a period of 15 months before and after surgery. VFI, mean deviation (MD), and pattern standard deviation (PSD) before surgery were compared with those after surgery. Results:Median (25th and 75th percentiles) MD after cataract surgery [−10.52 dB (range, −19.25 to −4.86 dB)] was significantly better (P=0.003) than that before surgery [−11.74 dB (range, −20.61 to −7.15 dB)]. Median PSD after surgery [4.76 dB (range, 2.48 to 9.83)] was worse (P=0.01) than that before surgery [3.50 dB (range, 1.93 to 8.20 dB)] when eyes with MD better than −20 dB were considered (41 eyes). VFI after surgery [80% (range, 44% to 94%)] was similar (P=0.92) to that before surgery [77% (range, 37% to 92%)]. MD improved while VFI remained unchanged in both nuclear sclerotic (n=41) and posterior subcapsular cataracts (n=12). Conclusions:MD and PSD were significantly affected, whereas VFI was not affected by cataract. VFI may be a more robust measure of VF damage than MD or PSD in glaucomatous eyes with coexisting cataracts.

Relationship between intraocular pressure and rate of visual field progression in treated glaucoma.

Purpose:To evaluate the relationship between intraocular pressure (IOP) and the rate of visual field (VF) progression in treated glaucoma. Methods:In a clinic-based, retrospective study, data of consecutive primary open-angle and angle-closure glaucoma patients with ≥5 VFs between 1989 and 2008 were analyzed. The Guided Progression Analysis software, which provides the rate of change of Visual Field Index per year, was used to assess the rate of progression (ROP). IOP measurements during the VF examination visits were extracted, and mean, peak, and fluctuation (SD) of IOP during the follow-up were calculated. Relationships between IOP parameters and ROP were analyzed using regression models. Other risk factors evaluated were age, sex, type of glaucoma, presence of hypertension and diabetes, severity of VF loss at presentation, glaucoma surgery during follow-up, number of antiglaucoma medications, and follow-up duration. Results:During the study period, 296 eyes of 213 glaucoma patients had undergone ≥5 VFs. IOP fluctuation was the only IOP parameter significantly associated with ROP (&bgr;=−0.37, P=0.02). Evaluated in a multivariate model with other risk factors, the severity of VF damage at presentation (&bgr;=0.08, P=0.002) and IOP fluctuation (&bgr;=−0.35, P=0.02) remained significantly associated with ROP. Greater IOP fluctuation was seen in eyes undergoing glaucoma surgery and eyes requiring more antiglaucoma medications during follow-up. Conclusions:Long-term IOP fluctuation was the most important IOP parameter associated with increased ROP of glaucomatous VF loss. This association is likely due to the confounding effect of enhanced therapy in eyes suspected to be progressing.

Glaucoma in microspherophakia: presenting features and treatment outcomes.

Purpose:To report the clinical features, management, and treatment outcomes of glaucoma in microspherophakia. Methods:Medical records of 159 eyes of 80 subjects with microspherophakia were reviewed. The clinical features at presentation, presence of glaucoma, methods of treatment, and their outcomes were noted. Glaucoma was diagnosed based on intraocular pressure (IOP)≥22 mm Hg on 2 different occasions and/or glaucomatous optic disc damage. Angle closure was defined as occludable angles >270 degrees with or without presence of peripheral anterior synechiae. Results:Glaucoma was diagnosed in 81 eyes (51%). The mean age of subjects was 20±13 years, mean refractive error was −13.5±5.5, the mean IOP was 27.7±11.1 mm Hg. IOP≥22 mm Hg was present in 84% of eyes, disc damage in 59% of the eyes, 75% eyes had angle closure, and 25% had open angle on gonioscopy. Subluxation of crystalline lens was seen in 53 eyes and 14 eyes had dislocation of the lens; systemic associations were present in 21 subjects (3 Marfan syndrome, 18 Weill-Marchesani syndrome). Nine eyes out of 51 and 2 out of 16 eyes responded to medical treatment and laser iridotomy, respectively. Of the 48 eyes that required surgical intervention, 24 eyes underwent trabeculectomy. Complete success probability of trabeculectomy was 86% [95% confidence interval (CI), 63%-95%] at 6 months, 77% (95% CI, 53%-90%) at 1 year, which was maintained till 7 years, and reduced to 61% (95%CI, 26%-84%) at 8 years. Nearly 20% of eyes at presentation and 30% of the eyes at last follow-up were blind due to glaucoma. Conclusions:More than half of the eyes with microspherophakia in this series presented with glaucoma; angle closure was the predominant form of glaucoma. Blindness due to glaucoma in microspherophakia was 20% to 30%.

Effect of optic disc size and disease severity on the diagnostic capability of glaucoma imaging technologies in an Indian population.

PurposeTo evaluate the influence of optic disc size and disease severity on the diagnostic validity of optical coherence tomography (Stratus OCT), scanning laser polarimetry [GDx variable corneal compensator (VCC)], and confocal scanning laser ophthalmoscopy [Heidelberg retina tomograph II (HRT II)] in Indian eyes with glaucoma. MethodsNinety-five normal and 125 glaucoma patients underwent imaging with Stratus OCT, GDx VCC, and HRT II. One eye of each person was randomly selected for analysis. Using disc area determined on HRT II, discs were classified as small (<2 mm2), moderate (2 to 3 mm2), and large (>3 mm2). The parameter with the best sensitivity for each device, at a fixed specificity, was compared for different disc sizes. Logistic marginal regression was used to study the effect of disc size and disease severity (mean deviation on standard automated perimetry) on the diagnostic performance of these imaging devices. ResultsAt a fixed specificity of 84.2%, the sensitivity of HRT II was significantly different for varying disc sizes (P=0.0004). The sensitivities for dissimilar disc sizes were not significantly different for the GDx VCC (P=0.928) or Stratus OCT (P=0.381). Logistic marginal regression also showed that sensitivity of HRT II increased with increasing disc size, whereas sensitivity of OCT and GDx were independent of the disc size. The sensitivity of all 3 technologies increased with increasing disease severity (decreasing mean deviation). ConclusionsOptic disc size affects the diagnostic capability of HRT II but not that of GDx VCC or Stratus OCT. The sensitivity of all 3 imaging technologies increased with increasing disease severity.

Choroidal thickness in diabetic patients of Indian ethnicity

Purpose: To evaluate choroidal thickness (CT) change in various grades of diabetic retinopathy (DR) in comparison to age-matched healthy subjects. Methods: This prospective observational study included 227 eyes of 125 subjects with diabetes (study group: 58 females) and 197 eyes of 110 age-matched healthy subjects (control group: 66 females). Collected data included age, gender, duration of diabetes, glycemic control, comprehensive ocular examination, fundus photography, and CT measurement on spectral domain ocular coherence tomography using enhanced depth imaging. Results: Mean age in the study group was 57.0 ± 9.37 years (43–73 years). The mean age was 41.48 ± 5.43 years in the control group. Subjects with diabetes with (252.8 ± 55.6 microns) and without (261.71 ± 51.8 microns) retinopathy had significantly thinner choroids when compared to the control group (281.7 ± 47.7 microns; P = 0.032). Seventy-four of 227 eyes did not have any evidence of DR, 89 eyes had features of nonproliferative diabetic retinopathy (NPDR), and 33 eyes had treatment naïve proliferative diabetic retinopathy (PDR). Thirty-one PDR eyes had received previous laser photocoagulation. Subjects with diabetes without retinopathy had a greater subfoveal choroidal thickness (SFCT) than subjects with diabetes with retinopathy (P < 0.001). Eyes with PDR (243.9 ± 56.2 microns) had thinner SFCT than those with NPDR (238.98 ± 111.23 microns). There was no difference in the SFCT between treated (laser photocoagulation done; 251.784 ± 103.72 microns) and treatment naïve PDR (258.405 ± 89.47 microns, P = 0.23). Conclusions: Control eyes had greater SFCT compared to subjects with diabetes, with and without retinopathy. The thinning progressed with increasing severity of DR. Choroidal thinning may contribute to DR pathogenesis.

Choroidal thickness in macular telangiectasia type 2.

Purpose: To assess the choroidal thickness changes in eyes with macular telangiectasia Type 2 and their relationship with the integrity of outer retinal structures and visual acuity. Methods: This is a prospective observational study that included 81 eyes (41 subjects) with macular telangiectasia Type 2, including 21 women who underwent enhanced depth choroidal imaging. The choroidal thickness measurements were made at the fovea and at 5 points with an interval of 500 &mgr;m in both directions, nasal and temporal from the fovea, and were compared with age-matched healthy subjects. Masked observers assessed the outer retinal structure integrity. Stepwise regression was used to find the relationship between age, spherical equivalent, central macular thickness, integrity of the inner segment/outer segment junction, external limiting membrane integrity, and subfoveal choroidal thickness (SFCT). Results: The mean age of the subjects was 55.2 ± 7.8 years in study subjects. The mean SFCT was 274.6 ± 45.7 &mgr;m. There was no significant difference between the SFCT in eyes with macular telangiectasia Type 2 and age-matched healthy subjects (P = 0.38). There was no correlation between the visual acuity (r = 0.008); integrity of inner segment/outer segment (r = 0.54); external limiting membrane (r = 0.47); central macular thickness (r = 0.31) and SFCT. Conclusion: Choroidal thickness did not vary between eyes with macular telangiectasia Type 2 and age-matched healthy subjects. There was no correlation between SFCT and visual acuity, and integrity of the outer retinal structures and central macular thickness.

Scanning the macula for detecting glaucoma

Background: With the advent of spectral domain optical coherence tomography (SDOCT), there has been a renewed interest in macular region for detection of glaucoma. However, most macular SDOCT parameters currently are thickness parameters which evaluate thinning of the macular layers but do not quantify the extent of area over which the thinning has occurred. We therefore calculated a new macular parameter, ganglion cell complex surface abnormality ratio (GCC SAR) that represented the surface area over which the macular thickness was decreased. Purpose: To evaluate the ability of SAR in detecting perimetric and preperimetric glaucoma. Design: Retrospective image analysis. Materials and Methods: 68 eyes with perimetric glaucoma, 62 eyes with preperimetric glaucoma and 165 control eyes underwent GCC imaging with SDOCT. SAR was calculated as the ratio of the abnormal to total area on the GCC significance map. Statistical Analysis: Diagnostic ability of SAR in glaucoma was compared against that of the standard parameters generated by the SDOCT software using area under receiver operating characteristic curves (AUC) and sensitivities at fixed specificities. Results: AUC of SAR (0.91) was statistically significantly better than that of GCC average thickness (0.86, P= 0.001) and GCC global loss volume (GLV; 0.88, P= 0.01) in differentiating perimetric glaucoma from control eyes. In differentiating preperimetric glaucoma from control eyes, AUC of SAR (0.72) was comparable to that of GCC average thickness (0.70, P> 0.05) and GLV (0.72, P> 0.05). Sensitivities at specificities of 80% and 95% of SAR were comparable (P > 0.05 for all comparisons) to that of GCC average thickness and GLV in diagnosing perimetric and preperimetric glaucoma. Conclusion: GCC SAR had a better ability to diagnose perimetric glaucoma compared to the SDOCT software provided global GCC parameters. However, in diagnosing preperimetric glaucoma, the ability of SAR was similar to that of software provided global GCC parameters.

Choroidal thickness profile in Retinitis Pigmentosa – Correlation with outer retinal structures

Purpose To compare the choroidal thickness (CT) of subjects with Retinitis Pigmentosa (RP) with age-matched healthy subjects and to correlate the visual acuity with retinal parameters including central macular thickness (CMT), inner segment/outer segment junction (IS/OS junction) integrity, external limiting membrane (ELM) integrity and choroidal thickness in subjects with RP. Methods Eighty-eight eyes (69 patients) with typical RP and 188 eyes of 104 healthy subjects were enrolled between September 2012 and January 2013. All subjects underwent a comprehensive ocular examination including choroidal imaging using enhanced depth imaging with spectral domain optical coherence tomography. Outcome measures were CT difference between RP and age-matched healthy subjects; and correlation of various factors such CMT, IS/OS junction integrity, ELM integrity, and CT with visual acuity. Results Among RP subjects, mean age was 31.39 ± 13.4 years with a mean BCVA of 0.99 ± 0.94 logMAR. Mean spherical equivalent was −0.6 ± 1.6D. Mean CMT was 148.48 ± 119 μm. Mean subfoveal CT was 296.9 ± 72 μm. Mean IS/OS and ELM integrity was 42.2 ± 46.6% and 43.75 ± 45.7%, respectively. The mean age was 40.0 ± 13.5 years with a mean spherical equivalent of 0.18 ± 0.6D for the normal age-matched healthy group. Mean subfoveal CT was 283.1 ± 47.8 μm. CT at various locations in patients of various ages in the RP group did not show any statistical significant difference (P = ≫0.05) in comparison with age-matched healthy subjects. On multivariate regression, ELM percentage integrity had the strongest association with best corrected visual acuity, followed by IS/OS junction percentage integrity. Subfoveal choroidal thickness had very weak correlation with visual acuity as well other retinal parameters. There was a significant difference in the outer retinal structure integrity (p = 0.002) and CMT (p = 0.02) between the eyes with good (⩾20/200) and poor vision (<20/200), but not in subfoveal choroidal thickness (p = 0.3). Conclusions Our study results did not show any significant difference in choroidal thickness between subjects with RP and age-matched healthy subjects. Choroidal thickness correlated better with the age but not with the vision or outer retinal structures in eyes with RP. Outer retinal structure integrity and CMT had a better correlation with visual acuity.