Acute Solar Retinopathy Imaged With Adaptive Optics, Optical Coherence Tomography Angiography, and En Face Optical Coherence Tomography

Key Points

Question

What is the structural change seen with acute solar retinopathy on high-resolution in vivo en face imaging?

Findings

In this case of a young adult woman who presented 3 days after viewing a solar eclipse with classic symptoms of solar retinopathy, adaptive optics scanning light ophthalmoscopy provided high-resolution images of foveal cone photoreceptor mosaic disturbance, and en face optical coherence tomography showed corresponding reflectivity changes. Optical coherence tomography angiography was normal in both eyes, and microperimetry showed an absolute central scotoma in the more affected eye.

Meaning

Acute solar retinopathy can result in localized foveal cone photoreceptor injury and dysfunction.

Abstract

Importance

Solar retinopathy is a rare form of retinal injury that occurs after direct sungazing.

Objective

To enhance understanding of the structural changes that occur in solar retinopathy by obtaining high-resolution in vivo en face images.

Design, Setting, and Participant

Case report of a young adult woman who presented to the New York Eye and Ear Infirmary with symptoms of acute solar retinopathy after viewing the solar eclipse on August 21, 2017.

Main Outcomes and Measures

Results of comprehensive ophthalmic examination and images obtained by fundus photography, microperimetry, spectral-domain optical coherence tomography (OCT), adaptive optics scanning light ophthalmoscopy, OCT angiography, and en face OCT.

Results

The patient was examined after viewing the solar eclipse. Visual acuity was 20/20 OD and 20/25 OS. The patient was left-eye dominant. Spectral-domain OCT images were consistent with mild and severe acute solar retinopathy in the right and left eye, respectively. Microperimetry was normal in the right eye but showed paracentral decreased retinal sensitivity in the left eye with a central absolute scotoma. Adaptive optics images of the right eye showed a small region of nonwaveguiding photoreceptors, while images of the left eye showed a large area of abnormal and nonwaveguiding photoreceptors. Optical coherence tomography angiography images were normal in both eyes. En face OCT images of the right eye showed a small circular hyperreflective area, with central hyporeflectivity in the outer retina of the right eye. The left eye showed a hyperreflective lesion that intensified in area from inner to middle retina and became mostly hyporeflective in the outer retina. The shape of the lesion on adaptive optics and en face OCT images of the left eye corresponded to the shape of the scotoma drawn by the patient on Amsler grid.

Conclusions and Relevance

Acute solar retinopathy can present with foveal cone photoreceptor mosaic disturbances on adaptive optics scanning light ophthalmoscopy imaging. Corresponding reflectivity changes can be seen on en face OCT, especially in the middle and outer retina. Young adults may be especially vulnerable and need to be better informed of the risks of viewing the sun with inadequate protective eyewear.

This case report enhances understanding of the structural changes that occur in solar retinopathy by obtaining high-resolution in vivo en face images.

Introduction

Solar retinopathy is a rare form of retinal injury that results from direct sungazing. Previous reports have described features of solar retinopathy imaged with optical coherence tomography (OCT), fundus autofluorescence, microperimetry, and fluorescein angiography. Histological reports suggest that the primary site of pathology is in the foveal photoreceptor outer segments and retinal pigment epithelium. To obtain high-resolution in vivo images of the site of pathology in solar retinopathy, we imaged both eyes of a patient diagnosed as having acute solar retinopathy with adaptive optics scanning light ophthalmoscopy (AOSLO), OCT angiography, and en face OCT.

Report of a Case

During the solar eclipse of August 21, 2017, a woman in her 20s viewed the solar rim several times for approximately 6 seconds without protective glasses and then again for approximately 15 to 20 seconds with a pair of eclipse glasses (unknown manufacturer). She reports looking at the eclipse with both eyes open. The peak obscuration of the sun’s area by the moon was approximately 70%. Four hours later, she noted blurred vision, metamorphopsia, and color distortion, which were worse in her left eye. She also reported seeing a central black spot in the left eye. Best-corrected visual acuity on presentation following the eclipse was 20/20 OD and 20/25 OS. She was noted to be left-eye dominant, with no history of ocular disease or medication use. Intraocular pressure and anterior segment examinations of both eyes were unremarkable. Fundus examination of the right eye was unremarkable (Figure 1A), while the fovea of the left eye revealed a yellow-white spot (Figure 2A). Amsler grid was normal in the right eye but showed a central notched annulus-shaped absolute scotoma in the left eye (Figure 3B, insert, flipped vertically). Microperimetry (CenterVue) was normal in the right eye but showed multiple areas of decreased sensitivity paracentrally with a central absolute scotoma in the left eye (Figure 2B). Spectral-domain OCT (Heidelberg Engineering) showed abnormal outer segment hyperreflectivity and discontinuity of the interdigitation zone in the right eye (Figure 1B) and near full-thickness hyperreflectivity at the center of the fovea, with hyporeflectivity of the outer segment and interdigitation zone in the left eye (Figure 2C).

Figure 1. Right Eye: Fundus, Optical Coherence Tomography, and Adaptive Optics (AOSLO).

Arrows in fundus photograph show the location of optical coherence tomography images. Square brackets in optical coherence tomography show the dimensions of AOSLO imaging.

Figure 2. Left Eye: Fundus, Microperimetry, and Optical Coherence Tomography.

Arrows in fundus photograph show the location of optical coherence tomography images. Square brackets in optical coherence tomography images show the dimensions of adaptive optics imaging.

Figure 3. Left Eye: Adaptive Optics.

Insert (B) shows the patient’s Amsler drawing of her absolute scotoma (flipped vertically to correspond to adaptive optics scanning light ophthalmoscopy [AOSLO] image).

We used a custom AOSLO with confocal and split-detector optics to image the cone photoreceptor mosaic at the fovea (image dimensions, 1.75 × 1.75°). In the right eye, confocal AOSLO showed a small region of hyporeflectivity, indicating the presence of nonwaveguiding photoreceptors, while corresponding split-detector AOSLO image revealed disruption of photoreceptor structure with the presence of few enlarged inner segments (Figure 1C and D). In the left eye, confocal AOSLO image showed a large area with ambiguous reflectivity owing to abnormal and nonwaveguiding photoreceptors, while the corresponding split-detector AOSLO image showed the sparse intact inner segments within the area of photoreceptor disruption (Figure 3).

Both OCT angiography and en face OCT (Optovue) images were automatically segmented in the regions of the superficial capillary plexus/inner retina, deep capillary plexus/middle retina, outer retina, and choriocapilaris (image dimensions, 3 × 3 mm). Optical coherence tomography angiography images of both eyes appeared normal. En face OCT images of the outer retina in the right eye showed a small circular area of hyperreflectivity inferior to the center of fovea with central hyporeflectivity (Figure 4C); corresponding change was also seen in the region of the choriocapillaris as a hyporeflective area (Figure 4D). En face OCT images in the left eye showed a hyperreflective disturbance that intensified with depth through the inner retina to the middle retina and becoming mostly hyporeflective, with central areas of hyperreflectivity in the outer retina. Corresponding spots of hyporeflectivity were also seen in the region of the choriocapillaris (Figure 5).

Figure 4. Right Eye: En Face Optical Coherence Tomography (OCT) and OCT Angiography.

A small circular area of hyperreflectivity with central hyporeflectivity is seen in the outer retina. Corresponding hyporeflectivity is also seen in the choriocapillaris. The OCT angiography images were normal (not shown).

Figure 5. Left Eye: En Face Optical Coherence Tomography (OCT) and OCT Angiography.

OCT angiography images were normal (not shown).

The patient was monitored and advised to use certified eclipse-viewing glasses when looking at the sun. Six weeks after the eclipse, the patient’s central scotoma in the left eye persisted.

Discussion

Solar retinopathy is a rare form of retinal injury that results from direct sungazing and is usually reported following eclipse viewing. Proposed mechanisms of injury include photochemical toxicity generated by excess short-wavelength visible light and thermal injury from near-infrared radiation. Histological studies have localized the damage to the foveal photoreceptor outer segments and the retinal pigment epithelium. Acutely, a yellow-white spot is seen in the fovea, which appears to correspond to changes in the hyperreflective photoreceptor bands on OCT. Chronically, the yellow-white spot may fade or evolve into a reddish cystlike lesion with surrounding mottled pigmentation that appears as hyporeflectivity of photoreceptor bands on OCT. Consistent with these previous reports, en face OCT showed corresponding hyperreflectivity at the fovea in the middle retina (Figure 5B) and mixed hyporeflectivity and hyper-reflectivity in the outer retina of the left eye (Figure 5C). The hyperreflectivity is likely related to photoreceptor injury and disorganization, while hyporeflectivity may suggest photoreceptor apoptosis and ensuing atrophy. Perhaps if this patient had undergone en face OCT immediately after viewing the eclipse, only hyperreflective changes would have been seen and would be consistent with a hyperacute injury before completion of the apoptotic pathway. The shape of the lesion on en face OCT and AOSLO in the left eye is a reflection of the patient’s scotoma on Amsler grid and resembles the solar rim during a partial solar eclipse. During a partial solar eclipse, when part of the sun’s core remains visible, viewing the solar rim without eclipse-viewing glasses with special-purpose solar filters can lead to severe solar retinopathy with an absolute central scotoma. Young adults, whether owing to clearer optical media, larger pupils, or poorer recognition of the dangers of viewing the eclipse with improper protective eyewear, may be especially susceptible.

Adaptive optics imaging enhances the resolution of retinal imaging devices by correcting ocular-induced wavefront aberrations, allowing in vivo visualization of cellular structures. In this patient, adaptive optics provided cellular level images of the disturbed photoreceptor mosaic. Significant cone outer and inner segment mosaic disruption was evident in the left eye (Figure 3). This annulus of nonwaveguiding cones was suspicious for, but not indicative of, definitive photoreceptor cell death. However, the fact that the patient reported an absolute scotoma that corresponded in shape to the lesion seen on AOSLO suggests absence of photoreceptor function in the lesion. It remains to be seen whether the patient can recover any visual function from this region of disturbed photoreceptors in the future. The absence of a corresponding scotoma in the right eye to the lesion seen on AOSLO may be explained by either the small size of the lesion, the fact that it is in her nondominant eye, or perhaps owing to the fact that the lesion is chronic and not owing to solar retinopathy (the observation that the periphery of the lesion demonstrates such an abrupt transition from normal to nonwaveguiding photoreceptors is suggestive of this).

Conclusions

Acute solar retinopathy can present with foveal cone photoreceptor mosaic disturbance on AOSLO. En face OCT showed corresponding reflectivity changes at the fovea. The lesion area on AOSLO and en face OCT are a reflection of the shape of the photic source. When severe, solar retinopathy can cause an absolute scotoma. Young adults may be especially vulnerable and need to be better informed of the risks of directly viewing the sun without protective eyewear.