Quantifying microstructural changes in retinitis pigmentosa using spectral domain - optical coherence tomography.

BACKGROUND: Most patients of established retinitis pigmentosa (RP) have subnormal peripheral vision and heavily rely on central vision for their daily activities. Central visual acuity is dependent on photoreceptor survival at the macula. Identification of structural changes that precede visual loss is essential. The aim of this study was to correlate the Spectral Domain-Optical Coherence Tomography (SD-OCT) characteristics with visual acuity in patients with typical RP. METHODS: This was a retrospective, observational case series of 224 eyes of 113 RP patients conducted a tertiary eye care center. SD-OCT imaging was done for all eyes. Central retinal thickness (CRT), photoreceptor outer segment length (PROS), foveal outer segment pigment epithelial thickness (FOSPET) and ellipsoid zone (EZ) extent were measured. A new variable, FOSPET-PROS ratio (FPR), obtained by dividing FOSPET by PROS is defined and correlated to corrected distance visual acuity (CDVA) in logMAR using linear regression. RESULTS: Out of 113 patients, 71 were males and 42 females. Mean age of the patients was 35.4 ± 15.1 years. Mean CDVA was 0.33 ± 0.25 logMAR with no difference between the genders. Mean CRT (218.74 ± 83.5 µm) and FPR (1.63 ± 0.22) significantly correlated to CDVA with a correlation coefficient of r = - 0.139 (p = 0.048) and r = 0.842 (p = 0.0001), respectively. FOSPET (mean = 71.15 ± 13.8 µm) and PROS (mean = 44.85 ± 12.5 µm) did not show a significant correlation to CDVA, independent of FPR. CONCLUSIONS: Retinal microstructural changes on SD-OCT, especially the FPR, can be used as a surrogate marker to monitor disease progression in the central retina in degenerative diseases like RP.

Characteristics and quantification of vascular changes in macular telangiectasia type 2 on optical coherence tomography angiography.

BACKGROUND: Macular telangiectasia type 2 (MacTel 2) is a bilateral idiopathic, rare neurodegenerative disease with alterations in the macular capillary network leading to vision loss and is the most common of three subtypes. Optical coherence tomography angiography (OCTA) is a non-invasive imaging modality which helps understand the complex pathological changes, and images the blood vessels across different layers based on their flow characteristics. METHODS: A cross-sectional study was conducted on 56 eyes of Asian Indian eyes of 28 consecutive patients with MacTel 2 studied during a 3-month period in a tertiary eye care hospital of South India. Clinically diagnosed cases of MacTel 2 underwent fundus photography, spectral domain OCT and OCTA. Fluorescein angiography was performed only when clinically indicated. Mean capillary density was calculated using a MATLAB-based automated software. The images were thresholded and binarised to derive the mean value. RESULTS: The mean age at presentation was 60±5.2, with a female preponderance of 71.42%. Vascular network on OCTA shows an increase in the intervascular spaces with progressive capillary rarefaction and abnormal capillary anastomosis. The outer retina and choroid were involved during the later stages and showed a prominent vascular network. The mean capillary density of the superficial and deep layers was 39.99% and 39.03% as against 45.18% and 44.21% in the controls, respectively. There was a statistically significant difference between the two groups (p<0.01). There is a positive and statistically significant correlation between the superficial and deep layers. CONCLUSION: OCTA helps understand the pathology and disease progression better in MacTel 2.

Quantification of Vessel Density in Retinal Optical Coherence Tomography Angiography Images Using Local Fractal Dimension.

PURPOSE: To evaluate a fully automated local fractal dimension method to quantify vessel density and foveal avascular zone (FAZ) area in optical coherence tomography angiography (OCTA) images. METHODS: Fifty-two healthy Asian Indian eyes underwent imaging prospectively with OCTA system. Superficial and deep retinal vascular plexus was imaged. Local fractal analysis was applied to the OCTA images. A scan area of 3 × 3 mm was selected in the superficial and deep retinal layers. Foveal avascular zone area and vessel density were quantified in circular and sectoral zones around the fovea. A unique contour map of vessel density and dropout zones was developed to perform regional comparisons. RESULTS: Foveal avascular zone of superficial (0.35 ± 0.013 mm2) and deep (0.49 ± 0.012 mm2) retinal vascular plexus was segmented. The agreement between the manually segmented and local fractal dimension segmented FAZ area was 0.97 (95% confidence interval [CI]: 0.94-0.98) and did not change significantly with age (P = 0.94 and 0.21, respectively). The vessel density was greater in the deep than the superficial retinal vascular plexus (P < 0.0001). When the image was subdivided into sectors around the FAZ, inferior sector had greater vessel density than the others (temporal, superior, and nasal) in both superficial and deep retinal vascular plexus (P < 0.05). These observations were similar to recent studies on animal retinal vasculature map. CONCLUSIONS: A novel implementation of local fractal dimension to calculate vessel density and FAZ area was demonstrated. Age did not impact vessel density but sectoral analyses showed greater vessel density in the inferior zone.

Duane retraction syndrome type 1 with Usher syndrome type 2: an unreported association.

Duane retraction syndrome is characterized by globe retraction and palpebral fissure narrowing on adduction, with restriction of abduction, adduction, or both. Usher syndrome type 2 consists of congenital bilateral sensorineural hearing loss and retinitis pigmentosa. The authors present a case with a yet unreported association between Duane retraction syndrome type 1 and Usher syndrome type 2.

Prevalence of diabetes mellitus and hypertension among Indian glaucoma patients and evaluation of systemic therapy.

To study the prevalence and systemic control and evaluate the adequacy of therapy of diabetes mellitus (DM) and hypertension (HT) in glaucoma patients visiting a tertiary care eye facility at a university hospital. Consecutive cases with primary open-angle glaucoma (POAG) or primary angle-closure glaucoma (PACG) attending the outpatient services were evaluated for the presence of DM and HT and any systemic/ocular medications being taken were recorded. Of 615 glaucoma cases evaluated, 281 (45.7 %) were POAG and 334 (54.3 %) were PACG. The mean age was 58.19 ± 10.8 years with males comprising 60.5 % of the study group. Two hundred and ninety-two (47.5 %) glaucoma patients had HT and 181 (29.4 %) had DM, including 97 (15.8 %) patients who had both. One hundred and thirty-three (47.3 %) patients with POAG and 159 (47.6 %) patients with PACG had HT. Ninety-seven (34.5 %) POAG patients and 84 (25.1 %) PACG patients were diabetics. One hundred and sixty-one (55.1 %) HT patients had blood pressure above control levels and 88 (48.6 %) diabetics had uncontrolled blood sugars. Twenty-eight (9.6 %) patients with HT were found to be taking combined systemic and topical ß-blocker therapy. A large majority of adult glaucoma patients had concurrent systemic disease, which was not adequately controlled. Patients were using systemic medications with known interactions with ocular hypotensive medications. This study highlights the unmet need for better coordination between ophthalmologists and physicians to improve the overall health of glaucoma patients.

Tractor nail as impacted foreign body: rare case scenario.

A patient presented with a metallic nail impacted in the right orbital floor after being hit by a projectile. The nail was disimpacted and removed as guided by the radiograph image. Radiography proved helpful in forming a coherent scheme for case management.

Drug-induced Angle-Closure Glaucoma.

Drug-induced angle-closure glaucoma is an important entity for the ophthalmologist as well as the general physician as it represents a preventable cause of potential blindness. This brief review highlights the fact that a high index of suspicion, in a susceptible individual followed by confirmation on appropriate imaging modality (UBM, ultrasound or anterior segment OCT) can alleviate the threat to sight and also help to institute appropriate therapy.