From the Ophthalmology Department and Ophthalmic Research Center (MHJB, MS), Labbafinejad Medical Center, Shahid Beheshti Medical University, Tehran, Iran; Science and Research Institute (RS), Islamic Azad University, Tehran, Iran; University of Arizona (GAP), Phoenix, Arizona; and Tulane University (GAP), New Orleans, Louisiana.
Supported by the Ophthalmic Research Center of Shahid Beheshti University Medical Center, Tehran, Iran.
The authors have no financial or proprietary interest in the materials presented herein.
Address correspondence to Gholam A. Peyman, MD, 10650 W. Tropicana Circle, Sun City, AZ 85351. E-mail: firstname.lastname@example.org
Solar eclipse viewing is the most common cause of solar retinopathy.1 Photochemical/thermal damage to the retina as a result of unprotected solar eclipse viewing has presentations such as decreased visual acuity, central scotoma, chromatopsia, photophobia, and metamorphopsia. Initially, there may be loss of foveal reflex with a small yellow-white spot at the foveola that gradually fades. The subtle nature of clinical findings necessitates relying on retinal imaging, including optical coherence tomography (OCT) and scanning laser ophthalmoscopy for accurate diagnosis.2 Previous studies based on time-domain OCT findings in solar retinopathy have described hyporeflective or hyperreflective spaces at the level of the outer retina.3–8 Severity and extent of macular damage depends on severity and duration of exposure to solar light. In the current case report, we present spectral-domain OCT (SD-OCT) findings in three eyes of two cases of solar retinopathy, one with severe (one eye) and the other with mild damage (both eyes) due to unprotected viewing of a solar eclipse.
A 14-year-old boy was referred 10 days after unprotected viewing of a solar eclipse. He had visual blurring, with best-corrected visual acuity decreased to 20/80 in his right eye. On dilated fundus examination, the foveal reflex was absent and a small yellow-white spot near the foveola was evident (Fig. 1). SD-OCT (Topcon 3D OCT; Topcon, Tokyo, Japan) showed a preserved foveal contour and a normal vitreoretinal interface with a rod-shaped full-thickness hyperreflective signal at the fovea. This extended from the outer segments of the photoreceptors and retinal pigment epithelium (RPE) to the inner layer of the retina, representing whole layer burning of fovea. A small region of hyporeflectance was evident, punching out through the hyperreflecting layer of the outer segments of the photoreceptors and partially into the RPE hyperreflecting layer (Fig. 1). At 1-month follow-up, his visual acuity had not improved and remained 20/80.
Figure 1. Spectral-domain optical coherence tomography (left) and fundus image (right) of right eye of 14-year-old boy after unprotected viewing of a solar eclipse. Absence of foveal reflex and a central yellow-white spot is shown on the color fundus image. Spectral-domain optical coherence tomography shows increased foveal rod-shaped full-thickness reflectivity with punched out small region of hyporeflectance through the hyperreflecting layer of the outer segments of the photoreceptors.
A 38-year-old man was referred 2 weeks after unprotected viewing of a solar eclipse. He had visual blurring in both eyes and best-corrected visual acuity was 20/30 in both eyes. On dilated fundus examination, pigmentary stippling of the macular region was evident in both eyes. SD-OCT showed a preserved foveal contour and a normal vitreoretinal interface with a loss of the hyperreflective layer of the inner segment/outer segment (IS/OS) of the photoreceptor with fragmentation of the hyperreflective layer of the RPE in the foveal region (Fig. 2). At 1-month follow-up, visual acuity was 20/30 and he had only minute central scotoma.
Figure 2. Spectral-domain optical coherence tomography (left) and fundus images (right) of the right eye (upper photographs) and left eye (lower photographs). Fundus images show pigmentary stippling of macular region. Spectral-domain optical coherence tomography shows loss of the hyperreflective layer of the inner segment/outer segment border of the photoreceptor with fragmentation of the retinal pigment epithelium layer.
Solar retinopathy has been described in pilots, patients with mental illness, drug abuse history, and following religious rituals.9,10 Involvement is usually bilateral. Because of their transparent crystalline lenses, young patients with emmetropia are at greater risk of developing solar burns.5 A longstanding lesion may show an irregularly pigmented macula with foveal hypopigmentation.10 Visual acuity usually improves after 6 months. Patients usually regain 20/20 vision, but they may report permanent minute central scotomas.11
OCT is a noninvasive imaging technique used for tomographic mapping of the retina.12 It is useful in differential diagnosis and can reveal characteristic foveal alterations consistent with outer retinal damage in solar retinopathy. In comparison to conventional time-domain OCT, high-resolution SD-OCT offers better image resolution (3 to 5 μm in SD-OCT compared with 8 to 10 μm in time-domain OCT).13,14
Solar retinopathy may be attributed to thermal or photochemical damage mediated by intensive absorption of sunlight in the outer retina. Histopathologic studies in photic maculopathy demonstrate localized damage with degenerative changes, RPE necrosis, and photoreceptor layer damage at the fovea and parafovea.15,16 With SD-OCT, our ability to image microstructures in vivo has reached an unprecedented quasi histologic level. Refinement with SD-OCT technology, such as the combination of eye tracking with averaging of multiple B-scans, provide even more precise delineation. OCT may help clarify the processes involved in retinal structural changes following solar burn and help detect the severity of damage. In case 1, the entire macular layer was involved and the visual acuity of the 14-year-old boy did not improve beyond 20/80. In case 2, a mild form of acute solar retinopathy, only the outer layers of the retina including a small area of the IS/OS were involved, and visual acuity was 20/30.
Case 1 had watched the solar eclipse unprotected. He closed his left eye to have better focus and sharper view of the eclipse with his right eye. His sustained sun gaze, in comparison to the brief sun gaze in case 2, may justify differences in imaging and clinical findings between the two cases. In case 1, the inner retinal layer edema with hyperreflective spot seems correlated in location with the characteristic visible yellow spot on funduscopy. Decreased acuity in our patients was consistent with OCT-demonstrated abnormalities in the IS/OS of the photoreceptors and with concurrent involvement of the inner retinal layer in the macular region in case 1.
Histopathologic reports of eyes enucleated within 1 week of solar gazing15,16 describe mostly RPE or photoreceptor changes. OCT in case 1 showed that inner retinal layers were involved in addition to outer retinal layers. Future reports may elucidate this finding.
SD-OCT can precisely localize retinal layers damaged in solar retinopathy and has excellent correlation with clinical findings. This is useful in differential diagnosis when a detailed clinical history is unavailable. Ultra-high–resolution OCT and SD-OCT solar retinopathy findings have shown outer retinal involvement, mainly photoreceptors at the IS/OS junction. These reports involved cases more than 1 month after injury.17,18
OCT findings in early solar retinopathy, reported by Bechmann et al.3 with a first-generation OCT scanner, described hyperreflectivity in all foveal retinal layers, which resolved 1 week later. Codenotti et al.5 reported increased intraretinal reflectivity at the level of the inner foveal retina and reduced reflectivity of RPE in acute solar retinopathy, which later resolved. Our SD-OCT findings were more detailed and showed localization of outer layer involvement at the photoreceptor IS/OS junction.
We suspect that photoreceptor layer disruption may be a finding of great importance because it may better guide prognosis. SD-OCT is a powerful tool for evaluation of solar retinopathy. OCT findings are helpful for detection of lesion extension, provide a better understanding of the pathogenesis, and may predict visual outcome in such cases.
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