Temporal Macular Thinning on Spectral-Domain Optical Coherence Tomography in Proliferative Sickle Cell Retinopathy

Sickle cell retinopathy is associated with retinal ischemia due to sickling of red blood cells in retinal arterioles that supply nutrients to the inner retinal layers.^1,2 Proliferative sickle cell retinopathy (PSR) results in neovascularization caused by occlusion of the peripheral arteriole, typically at the branching points of the arterioles.³ Although neovascularization may be seen at the optic disc and the macula, PSR is primarily a peripheral ischemic retinal disease that results in vitreous hemorrhage and retinal detachment.¹ However, peripheral ischemia can easily be missed on clinical examination, and invasive techniques such as wide-field angiography are required to identify these changes in asymptomatic individuals.⁴

Spectral-domain (SD) optical coherence tomography (OCT) provides high-resolution cross-sectional images that have a high correlation with the histologic features of various vitreomacular disorders.⁵ In this case series, we describe the features on SD-OCT images of the macula in patients with PSR.

A 21-year-old African American man with a history of sickle cell disease (SS variant) was referred for an ocular evaluation. His visual acuity was 20/20 OU, and the results of anterior segment evaluation were unremarkable. Dilated fundus evaluation revealed a normal posterior pole and peripheral retinal pigmentary changes without any new vessels bilaterally Wide-field angiography (Spectralis; Heidelberg Engineering Inc, Heidelberg, Germany) with Staurenghi lens (Staurenghi 230 SLO Retina Lens; Ocular Instruments Inc, Bellevue, Washington) demonstrated peripheral capillary dropout with early neovascularization bilaterally. A cross-sectional SD-OCT scan (Spectralis) (measuring 6 × 6 mm) revealed thinning of the temporal macula, with selective loss of the retinal ganglion cell and nerve fiber layer (Figure 1A). A retinal thickness map confirmed the thinning (Figure 1B), and a 3-dimensional rendering highlighted the depression in the surface retinal contour corresponding to the thinning (Figure 1C).

A 42-year-old African American man with a history of sickle cell disease (SS variant) was referred for further treatment of a dense vitreous hemorrhage in his left eye. He underwent a pars plana vitrectomy for a nonclearing vitreous hemorrhage. After surgery, wide-field angiography revealed peripheral retinal ischemia in the other eye. A cross-sectional SD-OCT scan (measuring 6 × 6 mm) showed loss of the inner layers of the temporal macula (Figure 2), and the configuration of the loss of retinal thickness on the retinal map was similar to that in case 1.

A 22-year-old African American man with sickle cell disease (SS variant) and a best-corrected visual acuity of 20/20 OU was referred for dilated fundus evaluation, which revealed temporal peripheral sclerosed vessels with early neovascularization. Conventional fluorescein angiography demonstrated ischemia of the peripheral retina, with flat neovascularization. A cross-sectional SD-OCT scan revealed a similar configuration of the temporal macula, with loss of the inner retinal layers (Figure 3).

Sickle cell retinopathy is characterized by a number of ischemic chorioretinal events, including central and branch retinal artery occlusion, macular infarction, ischemic optic neuropathy, chorioretinal infarctions, and PSR.^1,6 Resolution of acute precapillary occlusion in the perimacular area may occur spontaneously, with the only signs of the infarction being a loss of the inner retinal layers and an irregularity of the light reflex from the internal limiting membrane, the retinal depression sign.⁷ In patients with chronic posterior pole ischemia, the posterior pole changes that have been described include microaneurysmlike dots, dark and enlarged segments of arterioles, hairpin-shaped venular loops, pathologic avascular zones, and widening and irregularities of the foveal avascular zone .^8,9

In its initial stages, PSR is characterized by peripheral retinal ischemia and neovascularization, the prompt detection and treatment of which prevents vitreous hemorrhage and retinal detachment.¹ Complete regression of peripheral new vessels is noted in more than 80% of patients who undergo peripheral circumferential scatter photocoagulation.¹⁰ Detection of peripheral retinal ischemia and neovascularization requires a diligent clinical examination and evaluation of the periphery with fluorescein angiography. Conventional fluorescein angiography documents retinal changes within 50° fields and is not useful in detecting peripheral retinal ischemia. Wide-field angiography using contact lens is often used to document the peripheral vascular changes in various retinal disorders, including central retinal vein occlusion and diabetic retinopathy.¹¹

Histopathologic studies of sickle cell retinopathy and other vaso-occlusive diseases have previously shown selective atrophy of the inner retinal layers (ganglion cell layer, inner nuclear layer, and müllerian glia of the retina) in several eyes after retinal infarction.² Spectral-domain OCT provides high-resolution cross-sectional images that have a high correlation with the histologic features of various vitreomacular disorders.⁵ There is an isolated case report of the use of SD-OCT to document retinal ischemic changes in a patient with sickle cell retinopathy.¹² However, the patient described had a macular infarction, with ischemia evident on clinical examination. In our case series, only 1 of the 3 patients was symptomatic owing to vitreous hemorrhage in 1 eye, and the others presented for a routine eye evaluation. Spectral-domain OCT in all 3 patients showed thinning of the temporal inner macula compared with retinal thickness in the same area in age-matched controls. The thinning presumably reflects the chronic ischemia of the retinal ganglion cells and nerve fibers coursing temporally as they head toward the optic nerve. The presence of temporal retinal thinning on SD-OCT images could indicate the need for further investigation with wide-field angiography to look specifically for peripheral areas of ischemia.

In conclusion, we found temporal macular thinning on SD-OCT images in 3 patients with PSR who had concurrent peripheral retinal ischemia. Further studies are required in a larger number of patients to detect a possible association between the retinal thinning seen on SD-OCT images and peripheral retina ischemia.

Correspondence: Dr Chalam, Department of Ophthalmology, University of Florida, Jacksonville, 580 W 8th St, Jacksonville, FL 32209 (kvchalam@aol.com).

Financial Disclosure: None reported.