Cases Illustrate Role of OCTA in Clinical Decision-Making
By Vishal Govindahari, MD, and Jay Chhablani, MD
OCT angiography (OCTA), being non-invasive and depth-resolved,1 is quickly establishing itself as a valuable technology for the ophthalmic office. The following two cases exemplify why we have incorporated OCTA into our daily practice and how it improves our clinical decision-making.
Case 1: Detection of CNVM in Chronic CSC
A 64-year-old male presented with gradual diminution of vision in his left eye for 6 to 8 months. Significant history included hypertension for 15 years, well-controlled with treatment. Best-corrected visual acuity (BCVA) was 20/25, N6 (~ J3-4) in the left eye and 20/20, N6 in the right eye. Clinical examination revealed altered retinal pigment epithelium pigmentation around the fovea in the right eye and involving the fovea in the left eye. Multimodal imaging suggested chronic central serous chorioretinopathy (CSC), active in the left eye. During the course of care, to address persistent subretinal fluid in the left eye, we treated the patient with one session of MicroPulse (Iridex) grid laser (5% duty cycle) and prescribed oral eplerenone.
Eighteen months from baseline, OCT showed signs of chronic CSC in both eyes. A double layer sign was noted in the right eye. In the left eye (Figure 1a), subretinal fluid, hyper-reflective subretinal deposits, and a fibrovascular pigment epithelial detachment (arrow in Figure 1a) were seen. Fluorescein angiography (FA) showed areas of stippled hyperfluorescence, and indocyanine green (ICG) angiography showed corresponding areas of choriocapillaris loss in both the right and left (Figure 1 b,c) eyes, all consistent with chronic CSC. Neither method of angiography showed definitive evidence of choroidal neovascular membranes (CNVMs). However, OCTA revealed the presence of neovascular networks in the outer retina and choriocapillaris in both the right and left (arrows in Figure 1 d,e) eyes. We presumed the CNVMs in the right eye to be quiescent given the lack of subretinal fluid on OCT.
Figure 1. The presence of subretinal fluid on OCT (a) and the presence of a well-defined neovascular network on OCTA (d,e) led to a definitive diagnosis of an active choroidal neovascular membrane despite the failure of conventional angiography (b,c) to demonstrate activity.
Based on the findings, we treated the left eye with three intravitreal anti-VEGF injections and another session of MicroPulse laser (5% duty cycle) over the subsequent 12 months. Treatment significantly decreased the area of the neovascular network as imaged by OCTA (Figure 2 a,b) and significantly decreased subretinal fluid as measured by OCT (Figure 2 c). We continue to follow the patient closely and vision has remained stable in both eyes.
Figure 2. Post-treatment, OCTA (a,b) showed significant reduction in the area of the neovascular network, and OCT (c) showed resolution of subretinal fluid.
The ability of OCTA to detect CNVMs secondary to CSC with high sensitivity and specificity has been established.2 This case demonstrates how OCTA can aid in the diagnosis of active as well as quiescent neovascular membranes in cases where conventional imaging fails. It also demonstrates its ability to detect quantitative as well as qualitative changes in neovascular membranes following treatment.
Case 2: Non-invasive Detection of Diabetic Macular Ischemia
A 59-year-old male reported that for approximately 4 months, he had been unable to clearly see distant objects. The patient, a known diabetic under treatment for 12 years, felt this was happening with both eyes. BCVA was 20/60, N18 (~ J13) in the right eye and 20/25, N6 (~ J3-4) in the left eye. Clinical examination revealed the presence of clinically significant macular edema and proliferative diabetic retinopathy (PDR) in both eyes. In addition, a vitreous hemorrhage was present in the right eye. OCT showed an epiretinal membrane, cystoid spaces, and multiple hyper-reflective foci suggestive of inflammatory pathology in both eyes (Figure 3 d). While the outer retinal layers appeared intact, the inner retinal layers were not distinctly distinguishable. OCTA demonstrated definitive signs of diabetic macular ischemia in both eyes: an irregular foveal avascular zone, capillary widening, and multiple dark spaces in the segments representing the superficial and deep capillary and choriocapillaris layers (Figure 3 a-c). Given the ischemic status and BCVA, we performed panretinal photocoagulation for PDR in the right eye and scheduled the patient for observation for macular edema in both eyes.
Figure 3. The presence of OCTA markers of ischemia (a-c) and corresponding structural changes on OCT (d) enabled correlation of structure and the patient’s reduced visual function. In addition, the detection of ischemia with OCTA, without the need to use an invasive angiography modality, confirmed the patient’s high level of risk for further complications and steered the treatment plan away from unwarranted anti-VEGF therapy.
OCTA has been shown to be very useful in the scenario of diabetic macular ischemia.3 It is a vital tool in understanding and prognosticating small vessel ischemia in the retinal and choroidal circulation secondary to diabetes. In this case, it enabled us to recognize macular ischemia non-invasively rather than use dye-dependent fluorescein angiography or indocyanine green, which are invasive, more time-consuming, and associated with risk. Evidence of ischemia on OCTA helped to confirm the patient’s high level of risk for further complications and led us to steer the treatment plan away from anti-VEGF therapy, which was unwarranted at the time. In addition, we were able to explain to the patient the reason for his reduced visual acuity and further educate him on the need for tighter blood sugar control to help prevent more vision loss.
1. Gao SS, Jia Y, Zhang M, et al. Optical coherence tomography angiography. Invest Ophthalmol Vis Sci. 2016;57(9):OCT27-OCT36.
2. Bonini Filho MA, de Carlo TE, Ferrara D, et al. Association of choroidal neovascularization and central serous chorioretinopathy with optical coherence tomography angiography. JAMA Ophthalmol. 2015;133(8):899-906.
3. Bradley PD, Sim DA, Keane PA, et al. The evaluation of diabetic macular ischemia using optical coherence tomography angiography. Invest Ophthalmol Vis Sci. 2016;57(2):626-631.
Dr. Govindahari and Dr. Chhablani are faculty members at the Smt. Kanuri Santhamma Centre for Vitreo-Retinal Diseases, LV Prasad Eye Institute in Hyderabad, India.