Aparna Rao

Pattern of Pseudoexfoliation Deposits on the Lens and Their Clinical Correlation- Clinical Study and Review of Literature

Purpose To study the clinical correlates of pattern of deposits over the lens in patients with pseudoexfoliation syndrome (PXF) or pseudoexfoliation glaucoma. Methods This retrospective observational study screened 346 patients with PXF seen in glaucoma clinic of a tertiary hospital from 2011–2013. Details like pattern of deposits, location on the lens surface and pupillary abnormalities in slit lamp photographs and their correlation with clinical and demographic variables, were analysed. Results A total of 84 eyes of 42 patients with bilateral PXF were included for the study. Glaucoma was seen in 30 eyes with baseline IOP of 24+3.8 mm Hg. Comparing the type of deposits, namely classical (n = 39 eyes), radial pigmentary (RP) form (n = 39 eyes) and combined classical and radial pigmentary (CR) forms (n = 6 eyes) of deposits, pupillary ruff atrophy was common in all forms while poor dilatation was rare in the RP type (n = 5 vs n = 25 in classical forms, p<0.001). Mean deviation (MD) was worse in the classical and CR form as compared to RP type with the latter presenting much earlier, 43±3.2 years vs 48±4.1 years in CR and 56±5.7 years in classical form, p<0.001. The baseline IOP in the RP group (18±2.3 mm Hg) was significantly lower than the other two forms (CR 20±3.2 mm Hg, classical 28±2.3 mm Hg), p<0.001, with only 2 eyes on anti-glaucoma drugs at presentation. Conclusion Pattern of exfoliation deposits may indicate the stage and severity of the disease process in evolution with the RP representing an earlier/less severe form of pseudoexfoliation syndrome.

Macular Ganglion Cell/Inner Plexiform Layer Measurements by Spectral Domain Optical Coherence Tomography for Detection of Early Glaucoma and Comparison to Retinal Nerve Fiber Layer Measurements

WE READ WITH INTEREST THE ARTICLE BY NOURI-MAHDAVI and associates evaluating the ganglion cell/inner plexiform layer (GC/IPL) measurements in early glaucoma. They found no significant improvement in performance of GC/ IPL parameters with both regional and global GC/IPL performing equally well for glaucoma detection. This is very encouraging and informative where other algorithms may be used for improving glaucoma detection. Such information regarding clinical application of imaging in glaucoma diagnosis is indeed useful for any clinician. Yet there are a few concerns that we would like to communicate. The authors have stated that they included eyes with reproducible field defects as glaucoma regardless of intraocular pressure or disc appearance. This does not apply well to clinical diagnosis of glaucoma, where field defects should correspond to optic nerve head changes of glaucoma. Though neurologic or retinal lesions were excluded by the authors, glaucomatous changes of the disc is primal for defining glaucoma since field defects could be simulated by other causes in this study, such as high myopia (cutoff for refractive errors was <8 diopters in this study). The authors have reported that a lower GC/IPL predicted a worse mean deviation in control subjects. The implication for such a finding in a normal eye (keeping in mind the inclusion criteria cited above) is not easily understandable. A careful look at the plots (Figure 1) shows that many glaucoma eyes had average retinal nerve fiber layer thickness (RNFLT) and GC/IPL measurements similar to controls. This again raises the question of whether this could have been because of visual fields being the inclusion criteria for glaucoma rather than disc changes. If the diagnosis of glaucoma could have included structural changes rather than functional damage, this discrepancy could have possibly not arisen. It is interesting that the authors found that adding the 2 best GC/IPL to RNFL parameters improved the performance of spectral-domain optical coherence tomography (pseudo-R improving from 65% to 75%); a quick re-look into Table 2 shows that glaucoma eyes had a wide confidence interval, implying that these may not be a true glaucoma cohort.

Aqueous misdirection in thyroid eye disease.

Secondary glaucoma in thyroid eye disease (TED) is attributed either to raised episcleral venous pressure or to mechanical compression induced trabecular meshwork damage by mucopolysaccharide deposition. While the mechanism for raised intraocular pressure (IOP) in TED is largely mechanical and is often evident during its active stage, our case presented with aqueous misdirection in the left eye during the inactive stage. Appropriate diagnostic tests should be ordered to diagnose cause of raised IOP, which would help determine appropriate treatment for the cause for secondary glaucoma in TED.

Change in retinal nerve fiber layer thickness after trabeculectomy.

apy had led to equalization of IOP with the only difference being therefore baseline IOP which therefore would reflect in mean IOP calculation between the 2 groups. So division into 2 groups in such a cohort would give very little details or differences as they may not actually belong to different groups at all after equalization of the risk factor by aggressive treatment. It is unclear why glaucoma change probability was used for assessing trend analysis while guided progression analysis give accurate values of change in visual field index and progression over time. It is unclear how disc hemorrhages were documented 3 to 4 months after detection in a retrospective study. Although disc hemorrhages were more frequent in group B, 14 of 49 eyes (28.6%) than group A, 14.3%, it is hard to understand why disc hemorrhage was risk factor for progression on the former when the rate of progression was similar. It may be possibly explained by aggressive treatment and precipitous IOP reduction in group B with resultant hemodynamic changes and disc hemorrhages.2,4 The wide confidence intervals for the hazard ratio (1.381 to 27.775) of disc hemorrhage as risk factor in group A with similar intervals in group B suggests that these results have to be accepted with caution. Despite these limitations, the clinical implications of such observations can be many-fold. One of the most important is that the baseline IOP (rather than mean IOP) may be the single most important determinant of progression irrespective of other risk factors. The other fact remains that the rate of progression equalizes by aggressive therapy even when baseline IOP is high which highlights the importance of IOP reduction in NTG cases.2 We may also be more cautious of systemic factors5 for eyes with lower baseline IOP and may warrant detailed systemic examination to rule out cardiovascular or systemic abnormalities in these eyes even after achieving target IOP with treatment.

Automated retinal nerve fiber layer defect detection using fundus imaging in glaucoma

Retinal nerve fiber layer defect (RNFLD) provides an early objective evidence of structural changes in glaucoma. RNFLD detection is currently carried out using imaging modalities like OCT and GDx which are expensive for routine practice. In this regard, we propose a novel automatic method for RNFLD detection and angular width quantification using cost effective redfree fundus images to be practically useful for computer-assisted glaucoma risk assessment. After blood vessel inpainting and CLAHE based contrast enhancement, the initial boundary pixels are identified by local minima analysis of the 1-D intensity profiles on concentric circles. The true boundary pixels are classified using random forest trained by newly proposed cumulative zero count local binary pattern (CZC-LBP) and directional differential energy (DDE) along with Shannon, Tsallis entropy and intensity features. Finally, the RNFLD angular width is obtained by random sample consensus (RANSAC) line fitting on the detected set of boundary pixels. The proposed method is found to achieve high RNFLD detection performance on a newly created dataset with sensitivity (SN) of 0.7821 at 0.2727 false positives per image (FPI) and the area under curve (AUC) value is obtained as 0.8733.

Recurrent neural network based retinal nerve fiber layer defect detection in early glaucoma

Retinal nerve fiber layer defect (RNFLD) is the earliest objective evidence of glaucoma in fundus images. Glaucoma is an optic neuropathy which causes irreversible vision impairment. Early glaucoma detection and its prevention are the only way to prevent further damage to human vision. In this paper, we propose a new automated method for RNFLD detection in fundus images through patch features driven recurrent neural network (RNN). A new dataset of fundus images is created for evaluation purpose which contains several challenging RNFLD boundaries. The true boundary pixels are classified using the RNN trained by novel cumulative zero count local binary pattern (CZC-LBP), directional differential energy (DDE) patch features. The experimental results demonstrate high RNFLD detection rate along with accurate boundary localization.

Bimatoprost (0.03%)-induced accommodative spasm and pseudomyopia.

Bimatoprost is a prostaglandin analogue used topically in the treatment of glaucoma. Commonly known side effects include eyelash growth, iris pigmentation and conjunctival hyperemia. While pseudomyopia is reported to be caused by parasympathomimetics, such an effect precipitated by bimatoprost has not yet been reported. We report a case demonstrating pseudomyopia and accommodative spasm caused after starting bimatoprost 0.03% in a young patient with glaucoma.