Do Not Stare Directly at a Solar Eclipse: The Risks to Your Eyes

A solar eclipse is always a rare spectacle that invites curiosity. However, behind its beauty, staring directly at the sun, even for just a few seconds, can carry serious risks that many people may not be aware of.

Without proper eye protection, sunlight can cause injury to the retina. One case report shows a young adult woman developed solar retinopathy after viewing the solar eclipse in 2017.

A solar eclipse does not make sunlight safe to view directly. During a partial eclipse, part of the sun’s surface remains visible, even if only as a crescent.

NASA explains that during a partial eclipse there is no phase of totality when the moon completely covers the sun’s bright surface. Therefore, an eclipse should not be viewed directly without special eye protection. The sunlight that remains visible can cause injury to the eyes.

This differs from the totality phase of a total solar eclipse. When the moon completely covers the sun’s bright surface, direct viewing can be done for a short time. However, eye protection must be used again as soon as the bright part of the sun begins to reappear.

The case occurred during the solar eclipse on 21 August 2017. In a report published in JAMA Ophthalmology, a woman in her twenties looked at the edge of the sun several times for about six seconds without protective glasses.

She then viewed the eclipse again for about 15 to 20 seconds using eclipse glasses from an unknown manufacturer.

About four hours after viewing the eclipse, she experienced blurred vision, visual distortion and more severe colour changes in her left eye. She also saw a black spot in the centre of her left eye.

Examination showed changes in the fovea, the central part of the retina responsible for central vision. In the left eye, examination showed more extensive disruption to the cone photoreceptors, the retinal cells responsible for capturing light.

High-resolution retinal imaging showed disruption to the arrangement of these photoreceptors. In the left eye, the area of disruption corresponded to the location of a central scotoma, an area in the centre of vision that has lost visual function.

The condition is called solar retinopathy, which is retinal injury caused by looking directly at the sun. The report shows that acute solar retinopathy can cause injury and functional impairment to the cone photoreceptors in the fovea.

Six weeks after the eclipse, the central scotoma in the woman’s left eye was still present. The shape of the lesion seen on retinal imaging of the left eye also matched the pattern of visual disturbance described by the patient. The researchers noted that the shape of the lesion resembled the edge of the sun during a partial eclipse.

The report concluded that acute solar retinopathy can cause injury to the cone photoreceptors in the fovea. The researchers also considered that young adults need better information about the risks.