Protecting vision during solar eclipses: Insights for ophthalmologists

(Image Credit: AdobeStock/kdshutterman)

Understanding the potential risks of viewing solar eclipses without proper eye protection is key for people in the path of the April 8 solar eclipse. It is important to be familiar with the many safe ways to view a solar eclipse.

The eclipse’s path of totality will cross 15 states, while the rest of the country will get glimpses of a partial solar eclipse. States in the path of totality include parts of Texas, Oklahoma, Arkansas, Missouri, Illinois, Kentucky, Indiana, Ohio, Pennsylvania, New York, Vermont, New Hampshire and Maine, as well as smaller parts of Michigan and Tennessee.

The eclipse is expected to draw many spectators along its path to view the phenomenon, creating a need for education on eye protection and safety. Looking at the eclipse without proper protection can cause damage to both the eye’s cornea and retina, including solar retinopathy.

Ophthalmologists can educate their patients about the importance of using certified solar viewing glasses or other safe viewing methods for the event. Patients need to consult experts to determine best options for viewing.

Sharon Fekrat, MD, a Duke retinal surgeon and chief editor of Curbside Consultation in Retina and Duke’s All About Your Eyes, explained that looking at the sun without protection can lead to solar retinopathy, a form of “burn” caused by exposure to intense solar radiation that results in retinal phototoxicity.

“Protective eyewear is necessary for preventing solar damage to the retina when viewing the sun and the eclipse,” she explained. “Cameras, telescopes, and binoculars are not designed for viewing the sun and do not offer any protection against solar damage.”

Esteban Peralta, MD, an ophthalmology resident physician at Duke, said it is important to caution people to beware of fake online glasses when buying protective eyewear.

“Certified solar viewing glasses should be obtained from a trusted source,” he explained.

A list of verified sources can be found online.

“One USA manufacturer of eclipse viewing glasses bought many of these ‘certified’ eclipse glasses online and found that they all failed safety testing,” he pointed out.

Certified lenses reduce visible light transmission by a factor of at least 100,000.¹ Alternatively, #14 welder’s glasses are also safe. Eclipse glasses should have the “ISO” (International Organization for Standardization) icon with reference number 12312-2.

“A solar eclipse is an extraordinary event that ought to leave lasting memories, not permanent eye damage,” Peralta added.

Fekrat explained that most patients with solar retinopathy develop symptoms immediately, but patients may be asymptomatic for a few days before presentation.

“Patients typically present with a central or paracentral afterimage with or without associated blurry central vision,” she said. “Other symptoms include chromotopsia, metamorphopsia, photophobia, and headache. Pain is atypical but has been reported in rare cases. It tends to affect both eyes.”²

Path of the solar eclipse across the United States (Photo Credit: Prevent Blindness)

Moreover, visual acuity could be normal or near normal, especially in children, so do not be fooled by 20/20 acuity.³

“Look for a central or paracentral scotoma on visual field testing since solar rays are focused on the macula with direct gaze,” Peralta added. “Most cases of photic retinopathy are mild with spontaneous resolution, but prolonged exposure may result in moderate to severe cases with permanent damage to the RPE and outer retinal layers.”

When a patient presents with vision issues after viewing the sun without proper protection, there are several signs ophthalmologists can look for when making a diagnosis.

“Photic injury from improper solar viewing causes maculopathy involving the outer retinal layers,” Fekrat said. “The resulting photochemical stress is believed to be a product of free radical formation.”

Fekrat added that careful foveal examination is important.

“Look for macular edema, an abnormal foveal light reflex, or yellowish discoloration of the fovea,” she said. “Note that central foveal atrophy from tissue loss may not be seen in the acute phase.”

Later signs include foveal distortion, pigment mottling, or even a macular hole. Photocoagulation does not typically occur.¹ OCT may demonstrate early macular edema.

Fekrat pointed out the classic finding on OCT is “excavation” of the outer hyperreflective layers.⁴ This corresponds to a defect at the interdigitation zone and the ellipsoid zone.⁵ Juxtafoveal microcystic cavities are also a sign of injury.

“Obtain fundus imaging with fundus autofluorescence, if available,” she said. “

Hyperautofluorescent spots may sometimes be seen.⁶

“Exam and imaging may be initially normal and evolve over the coming days to weeks,” she added. “Therefore, serial OCTs may help assess the extent and progression of foveal damage.”

When patients present with symptoms of solar retinopathy, it can be important to know when to treat and when to refer them to a retina specialist.

Because the condition is so rare, Peralta explained there are no established guidelines for treating solar retinopathy.

“A ‘few seconds’ of briefly glimpsing at the sun is unlikely to cause any significant damage,” he said. “Be wary of patients with more prolonged exposure.”

Most patients can demonstrate good recovery of visual acuity and spontaneous resolution of scotomata.

“For mild cases, close follow-up within one week of presentation is recommended to monitor for any subjective changes and for repeat OCT imaging,” Fekrat added. “Humphrey visual fields may also be repeated based on subjective findings and clinician judgment.”

Fekrat added that the referral of patients with abnormal OCT findings to a retina specialist is recommended.

“Those with a normal exam but with a high suspicion for solar retinopathy based on history can also be referred to a retina specialist, as observable fundus changes may take a few days to develop,” she explained. “On the other hand, those with mild symptoms and without objective imaging findings may be safely monitored for resolution.”

Peralta noted that it also is important to counsel patients to monitor their symptoms at home with an Amsler grid after a baseline eye exam.

“If patients do not have an Amsler grid at home and you do not have one in the office, you may print one off the Internet or the patient can use graph paper instead,” he said.

Fekrat and Peralta also offered some pearls to remember:

• The most common finding is a central scotoma with correlating changes in the ellipsoid zone on OCT, usually in both eyes.
• Closely examine the fovea for hyperreflective yellowish changes on fundus exam.
• The presence of a native lens is protective, likely due to UV-blocking chromophores.¹ Pseudophakia increases risk.
• Ask patients about viewing modalities. Did they view the sun with the naked eye? Did they utilize store-bought sunglasses? Or did they use their grandparent's telescope? History is important here.
• Individuals under the influence of psychoactive drugs or with certain behavioral health comorbidities may be at higher risk.
• Photosensitizing drugs such as cyclines increase the risk of phototoxicity.

References:

1. Mainster M. Guest Editorial Solar Eclipse Safety. Ophthalmology. 1998;105(1):9-10.

2. Codenotti M, Patelli F, Brancato R. OCT findings in patients with retinopathy after watching a solar eclipse. Ophthalmologica. 2002;216(6):463-466. doi:10.1159/000067540

3. Gregory-Roberts E, Chen Y, Harper CA, et al. Solar retinopathy in children. J AAPOS. 2015;19(4):349-351. doi:10.1016/j.jaapos.2015.05.009

4. Kaushik, Sushmita, MS; Gupta, Vishali, MS; Gupta, Amod M. Optical Coherence Tomography Findings in Solar Retinopathy. Ophthalmic Surgery, Lasers and Imaging. 2004;35(1):52-55.

5. Jain A, Desai RU, Charalel RA, Quiram P, Yannuzzi L, Sarraf D. Solar retinopathy: Comparison of Optical Coherence Tomography (OCT) and Fluorescein Angiography (FA). Retina. 2009;29(9):1340-1345. doi:10.1097/IAE.0b013e3181b0da88

6. Vora RA, Dossetor FM, Lowe RJ. Solar Eclipse Maculopathy. Ophthalmol Retin. 2018;2(2):169. doi:10.1016/j.oret.2017.09.022