Rupesh Agrawal

State of science: Choroidal thickness and systemic health

The choroid is a highly vascular structure; therefore, a wide range of systemic conditions can affect it. Conversely, choroid health may also give us insight into systemic health. With the emergence of optical coherence tomography, there has been a surge in the research on choroidal thickness and factors affecting it. Studies regarding the effect of systemic health on the choroid have largely been in the form of cross-sectional, prospective, and case studies. We offer a summary of recent findings on the topic.

Systematic Evaluation of Optical Coherence Tomography Angiography in Retinal Vein Occlusion.

PURPOSE To evaluate the clinical utility of optical coherence tomography angiography (OCTA) in patients with retinal vein occlusion (RVO), and to systematically compare OCTA images with changes seen on color fundus photography and fluorescein angiography (FA). DESIGN Reliability analysis. METHODS Eighty-one eyes of 76 patients with a history of RVO (branch, central, or hemicentral), both acute and chronic, underwent OCTA and color fundus photography. In 29 eyes, data were compared to FA imaging. Comparative and multimodal analysis of the 3 imaging procedures were performed. RESULTS We identified good agreement between FA and OCTA scans centered on the macula for capillary nonperfusion (intraclass correlation coefficient [ICC] 0.825 for the 3 × 3-mm scan and 0.891 for the 8 × 8-mm scan). Agreement for area of capillary changes (dilation, pruning, and telangiectasia) was also substantial (ICC 0.712 for the 3 × 3-mm scan and 0.787 for the 8 × 8-mm scan). For foveal avascular zone grading, agreement was good for the 3 × 3-mm scan (kappa = 1.000 for radius and kappa = 0.799 for outline) but poor for the 8 × 8-mm scan (kappa = 0.156 for radius and kappa = 0.600 for outline). The quality of the images obtained was an important issue for OCTA, as 15.1% of scans were nongradable, particularly in patients unable to maintain fixation. CONCLUSIONS OCTA is a quick, reliable, and noninvasive method to evaluate the area of capillary nonperfusion and foveal avascular zone morphology in patients with RVO. However, good fixation is a requirement for acquisition of good-quality images.

Choroidal vascularity index as a measure of vascular status of the choroid: Measurements in healthy eyes from a population-based study.

The vascularity of the choroid has been implicated in the pathogenesis of various eye diseases. To date, no established quantifiable parameters to estimate vascular status of the choroid exists. Choroidal vascularity index (CVI) may potentially be used to assess vascular status of the choroid. We aimed to establish normative database for CVI and identify factors associated with CVI in healthy eyes. In this population-based study on 345 healthy eyes, choroidal enhanced depth imaging optical coherence tomography scans were segmented by modified image binarization technique. Total subfoveal choroidal area (TCA) was segmented into luminal (LA) and stromal (SA) area. CVI was calculated as the proportion of LA to TCA. Linear regression was used to identify ocular and systemic factors associated with CVI and subfoveal choroidal thickness (SFCT). Subfoveal CVI ranged from 60.07 to 71.27% with a mean value of 65.61 ± 2.33%. CVI was less variable than SFCT (coefficient of variation for CVI was 3.55 vs 40.30 for SFCT). Higher CVI was associated with thicker SFCT, but not associated with most physiological variables. CVI was elucidated as a significant determinant of SFCT. While SFCT was affected by many factors, CVI remained unaffected suggesting CVI to be a more robust marker of choroidal diseases.

The role of anti-tubercular therapy in patients with presumed ocular tuberculosis.

Abstract Objective: To analyze the factors affecting the treatment outcome in patients with presumed ocular tuberculosis on anti-tubercular therapy (ATT). Methods: Retrospective chart review of patients with presumed ocular tuberculosis seen at a tertiary referral eye care center in the United Kingdom. Failure was defined as recurrence of inflammation within 6 months of completion of ATT. Results: There were a total of 175 patients with presumed ocular tuberculosis who had ATT. Patients with intermediate uveitis or panuveitis and those on immunosuppressive therapy had higher odds of treatment failure (p < 0.05) while those with more than 9 months of ATT (77, 79.38%) had less likelihood of failure. Conclusion: We present the largest case series of patients with presumed ocular tuberculosis in a low endemic area treated with ATT. Longer duration of treatment resulted in reduced risk of recurrence of inflammation, whereas immunosuppression adversely affected the final treatment outcome.

The Evaluation of Diabetic Macular Ischemia Using Optical Coherence Tomography Angiography

PURPOSE The purpose of this study was to compare optical coherence tomography (OCT) angiography to standard fluorescein angiography (FA) in the grading of diabetic macular ischemia. METHODS In our study, OCT angiography and traditional FA images were acquired from 24 diabetic patients. The level of diabetic macular ischemia in the superficial capillary plexus was graded with standard Early Treatment Diabetic Retinopathy Study (ETDRS) protocols and a comparison between conventional FA and OCT angiography was performed. The deep vascular plexus and choriocapillaris were also graded for macular ischemia. Additionally, flow indices were analyzed for all OCT angiography images. RESULTS We identified moderate agreement between diabetic macular ischemia grades for conventional FA and OCT angiography (weighted κ of 0.53 and 0.41). In addition, the intergrader agreement for the superficial, deep, and choriocapillaris scores was substantial (weighted κ of 0.65, 0.61, and 0.65, respectively). Finally, the parafoveal flow indices were shown to have a statistically significant relationship with diabetic macular ischemia grades for the superficial capillary plexus (P = 0.04) and choriocapillaris (P = 0.036), with a trend toward significance for the deep capillary plexus (P = 0.13). CONCLUSIONS We demonstrated moderate agreement between diabetic macular ischemia grading results for OCT angiography and conventional FA using standard ETDRS protocols. We also showed that OCT angiography images could be graded for diabetic macular ischemia with substantial intergrader agreement.

Assessment of red blood cell deformability in type 2 diabetes mellitus and diabetic retinopathy by dual optical tweezers stretching technique

A pilot cross sectional study was conducted to investigate the role of red blood cells (RBC) deformability in type 2 diabetes mellitus (T2DM) without and with diabetic retinopathy (DR) using a dual optical tweezers stretching technique. A dual optical tweezers was made by splitting and recombining a single Nd:YAG laser beam. RBCs were trapped directly (i.e., without microbead handles) in the dual optical tweezers where they were observed to adopt a “side-on” orientation. RBC initial and final lengths after stretching were measured by digital video microscopy, and a Deformability index (DI) calculated. Blood from 8 healthy controls, 5 T2DM and 7 DR patients with respective mean age of 52.4yrs, 51.6 yrs and 52 yrs was analysed. Initial average length of RBCs for control group was 8.45 ± 0.25 μm, 8.68 ± 0.49 μm for DM RBCs and 8.82 ± 0.32 μm for DR RBCs (p < 0.001). The DI for control group was 0.0698 ± 0.0224, and that for DM RBCs was 0.0645 ± 0.03 and 0.0635 ± 0.028 (p < 0.001) for DR group. DI was inversely related to basal length of RBCs (p = 0.02). DI of RBC from DM and DR patients was significantly lower in comparison with normal healthy controls. A dual optical tweezers method can hence be reliably used to assess RBC deformability.

CHOROIDAL VASCULARITY INDEX IN CENTRAL SEROUS CHORIORETINOPATHY.

Purpose: To evaluate choroidal vascularity index (CVI) in eyes with central serous chorioretinopathy (CSC) using an image binarization tool on enhanced depth imaging using spectral domain optical coherence tomography scans. Methods: In this retrospective cohort study, enhanced depth imaging optical coherence tomography scans of both eyes of patients with CSC were taken at baseline; they were segmented and compared with enhanced depth imaging optical coherence tomography scans of fellow eyes without CSC as well as age-matched healthy subjects. Subfoveal choroidal area (1,500 &mgr;m) was segmented into luminal area and stromal area using image binarization. Choroidal vascularity index was defined as the proportion of luminal area to the total circumscribed subfoveal choroidal area. Results: Eyes with acute CSC (32 eyes) had significantly higher CVI compared with their fellow eyes (27 eyes) (P < 0.0001), 19 eyes with resolved CSC (P < 0.0001) and with 30 eyes of age-matched healthy eyes (P < 0.0001). Fellow eyes of subjects with acute CSC also had significantly higher CVI compared with eyes with resolved CSC (P < 0.0001) and age-matched healthy eyes (P < 0.0001). Conclusion: Increased CVI suggests increased vascular component compared with the stromal component in acute CSC. Increased CVI was noted in fellow eye of the subjects with acute CSC in comparison with age-matched healthy subjects. The CVI could be a useful index for early diagnosis of CSC and to assess the treatment response after laser photocoagulation or photodynamic therapy.

Optical Coherence Tomographic Angiography in Type 2 Diabetes and Diabetic Retinopathy

Importance Optical coherence tomographic angiography (OCT-A) is able to visualize retinal microvasculature without the need for injection of fluorescein contrast dye. Nevertheless, it is only able to capture a limited view of macula and does not show leakage. Objectives To evaluate the retinal microvasculature using OCT-A in patients with type 2 diabetes as well as the association of OCT-A characteristics with diabetic retinopathy (DR) and systemic risk factors. Design, Setting, and Participants A prospective, observational study was conducted from January 1 to June 30, 2016, at medical retina clinics at the Singapore National Eye Center among 50 patients with type 2 diabetes with and without DR (n = 100 eyes). We examined the retinal microvasculature with swept-source OCT-A and a semiautomated software to measure the capillary density index (CDI) and fractal dimension (FD) at the superficial vascular plexus (SVP) and deep retinal vascular plexus (DVP). We collected data on histories of patients’ glycated hemoglobin A1c, hypertension, hyperlipidemia, smoking, and renal impairment. Main Outcomes and Measures The CDI and FD at the SVP and DVP for each severity level of DR and the association of systemic risk factors vs the CDI and FD. Results The mean (SD) glycated hemoglobin A1c of the 50 patients (26 men and 24 women; 35 Chinese; mean [SD] age, 59.5 [8.9] years) was 7.9% (1.7%). The mean (SD) CDI at the SVP decreased from 0.358 (0.017) in patients with no DR to 0.338 (0.012) in patients with proliferative DR (P < .001) and at the DVP decreased in patients with no DR from 0.361 (0.019) to 0.345 (0.020) in patients with proliferative DR (P = .04). The mean (SD) FD at the SVP increased from 1.53 (0.05) in patients with no DR to 1.60 (0.05) in patients with proliferative DR (P < .01) and at the DVP increased from 1.55 (0.06) in patients with no DR to 1.61 (0.05) in patients with proliferative DR (P = .02). For systemic risk factors, hyperlipidemia (odds ratio [OR], 9.82; 95% CI, 6.92-11.23; P < .001), smoking (OR, 10.90; 95% CI, 8.23-12.34; P < .001), and renal impairment (OR, 3.72; 95% CI, 1.80-4.81; P = .05) were associated with reduced CDI, while increased glycated hemoglobin A1c (≥8%) (OR, 8.77; 95% CI, 5.23-10.81; P < .01) and renal impairment (OR, 10.30; 95% CI, 8.21-11.91; P < .001) were associated with increased FD. Conclusions and Relevance Optical coherence tomographic angiography is a novel imaging modality to quantify the retinal capillary microvasculature in patients with diabetes. It can be potentially used in interventional trials to study the effect of systemic risk factors on the microvasculature that was previously not accessible in a noninvasive manner. The relevance of these findings relative to visual acuity, however, remains largely unknown at this time.

Choroidal Vascularity Index (CVI)--A Novel Optical Coherence Tomography Parameter for Monitoring Patients with Panuveitis?

Purpose To compute choroidal vascularity index (CVI) using an image binarization tool on enhanced depth imaging (EDI)-optical coherence tomography (OCT) scans as a non-invasive optical tool to monitor progression in panuveitis and to investigate the utility of volumetric data from EDI-OCT scans using custom image analysis software. Materials and Methods In this retrospective cohort study, segmented EDI-OCT scans of both eyes in 19 patients with panuveitis were taken at baseline and at 3-month follow-up and were compared with EDI-OCT scans of normal eyes. Subfoveal choroidal area was segmented into luminal (LA) and stromal interstitial area (SA). Choroidal vascularity index (CVI) was defined as the proportion of LA to the total circumscribed subfoveal choroidal area (TCA). Results The mean choroidal thickness was 265.5±100.1μm at baseline and 278.4±102.6μm at 3 months follow up (p = 0.06). There was no statistically significant difference in TCA between study and control eyes (p = 0.08). CVI in the control group was 66.9±1.5% at baseline and 66.4±1.5% at follow up. CVI was 74.1±4.7% at baseline and 69.4±4.8% at 3 months follow up for uveitic eyes (p<0.001). The % change in CVI was 6.2 ±3.8 (4.3 to 8.0) for uveitic eyes, which was significantly higher from % change in CVI for control eyes (0.7±1.1, 0.2 to 1.3, p<0.001). Conclusion The study reports composite OCT-derived parameters and CVI as a possible novel tool in monitoring progression in panuveitis. CVI may be further validated in larger studies as a novel optical tool to quantify choroidal vascular status.

Controversies in ocular trauma classification and management: review

Ocular trauma is a topic of unresolved controversies and there are continuous controversial and debatable management strategies for open-globe injuries (OGIs). International classification of ocular trauma proposed almost 15 years ago needs to be reviewed and to be more robust in predicting the outcome in the setting of OGIs. Anterior segment trauma involves controversies related to patching for corneal abrasion, corneal laceration repair, and medical management of hyphema. Timing of cataract surgery and intraocular lens implantation in the setting of trauma is still debated worldwide. There are unresolved issues regarding the management of OGIs involving the posterior segment. Timing of vitrectomy has been and will continue to be debated by proponents of early versus delayed intervention. The use of prophylactic cryotherapy and scleral buckle is still practiced differently throughout the world. The role of intravitreal antibiotics in posterior segment trauma in the absence of infection is still debated. Similarly, the use of vitrectomy versus vitreous tap in the setting of traumatic endophthalmitis is not fully resolved. In optic neuropathy, the role of intravenous methylprednisolone versus conservative management is always debated and still there are no evidence-based guidelines about the beneficial role of pulse steroid therapy. The role of optic canal decompression in the setting of acute traumatic optic neuropathy is also not conclusive. Orbital and adnexal trauma has been shown to adversely affect the outcome of OGI patients but both lids and orbital injury are not taken as preoperative variables in international ocular trauma classification. The timing of intervention in blow-out fracture is still debated. The pediatric age group, owing to the high risk of amblyopia and intraocular inflammation as well as strong vitreoretinal adhesions, has to be managed by different principles. Although the risk of sympathetic ophthalmia is very rare, it is always one of the key debated issues while managing traumatized eyes with no light perception vision. Prospective, controlled clinical studies are not possible in the OGI setting and this article reviews pertinent data regarding these management issues and controversies, and provides recommendations for treatment based on the available published data and the authors’ personal experience.