Answered on March 21, 2024
Observing a solar eclipse without proper eye protection can indeed lead to serious eye damage, including solar retinopathy, which is damage to the retina caused by direct sunlight exposure. The condition can result in symptoms such as visual disturbances or loss of vision. A prospective study following patients who observed the 1999 solar eclipse revealed that some individuals sustained visible retinal changes, and a subset remained symptomatic after several months.[1] The photoreceptors and retinal pigment epithelium, particularly in the posterior pole, are susceptible to damage from ultraviolet (UV) light, which can be a component of sunlight during an eclipse.[2] While the prognosis for acute UV retinopathy is generally favorable, with many cases fully recovering, there is a significant risk of chronic sequelae, including reduced acuity and lifelong central or paracentral scotomas.[2] Therefore, it is critical to use proper eye protection when viewing a solar eclipse to prevent retinal damage.

References

1.
Eclipse Burns: A Prospective Study of Solar Retinopathy Following the 1999 Solar Eclipse.

Wong SC, Eke T, Ziakas NG.

Lancet (London, England). 2001;357(9251):199-200. doi:10.1016/S0140-6736(00)03597-2.

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Leading Journal

Looking at the sun can cause focal burns to the retina. We prospectively followed up all patients who presented to Eye Casualty of Leicester Royal Infirmary having observed the solar eclipse of August, 1999. 45 patients attended, of whom 20 had visual symptoms and five had visible changes in the retina; four patients were still symptomatic after 7 months.

2.
Sunlight and Ultraviolet Radiation-Pertinent Retinal Implications and Current Management.

Begaj T, Schaal S.

Survey of Ophthalmology. 2018 Mar - Apr;63(2):174-192. doi:10.1016/j.survophthal.2017.09.002.

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Unprotected and prolonged exposure to ultraviolet (UV) light from sunlight, lasers, and arc welding leads to outer retinal damage. The photoreceptors and retinal pigment epithelium located in the posterior pole are particularly susceptible to this radiation. Classically known as solar retinopathy, this disorder frequently affects young individuals who have clear lenses and a propensity toward observing solar eclipses. Various imaging techniques aid the clinician in diagnosis, even if patients cannot recall an exposure event. By far the most utilized technique is optical coherence tomography that, in tandem with fluorescein angiography, and fundus autofluorescence, is crucial in ruling out other conditions. Fortunately, the prognosis of acute UV retinopathy is favorable, as most cases fully recover; however, a significant percentage of patients suffer from chronic sequelae: reduced acuity and lifelong central/paracentral scotomas. Thus, education toward understanding UV exposure risks, coupled with either abstinence or proper eye protection, is critical in preventing macular damage. We outline the various etiologies responsible for UV-induced retinopathy, describe the limited treatments available, and provide recommendations to minimize the potential devastating ophthalmic consequences as our society increases its reliance on UV-emitting technology and further engages in solar eclipse viewing.

Answered on March 21, 2024
The proper eye protection for viewing a solar eclipse involves using solar viewing or eclipse glasses that meet the ISO 12312-2 international safety standard. These glasses are designed to block out harmful ultraviolet, visible, and infrared radiation. Regular sunglasses, even very dark ones, or homemade filters are not safe for looking at the sun because they transmit thousands of times too much sunlight. Indirect viewing methods, such as a pinhole projector, can also be used to safely observe an eclipse without looking directly at the sun.[1] It is important to ensure that solar viewing glasses are not scratched or damaged before use, and to instruct patients to look away from the sun before putting on or removing the glasses to avoid accidental exposure.

References

1.
Solar Eclipse Observation: Some Simple Devices.

Handojo A.

Applied Optics. 1989;28(20):4293-7. doi:10.1364/AO.28.004293.

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The terrestrial solar irradiance is evaluated in view of the energy absorbed by the retina and the blue light hazard. The evaluated irradiance is compared with the known safety standard, to determine the safety requirement of solar eclipse observation devices. Simple devices are then proposed. The first is a folded pinhole camera, giving a magnified sun image from a relatively small box. The second is a pinhole projector, used to display the image in a large room, while the third is a compact multimirror periscope enabling one to see the sun sharper than with a pinhole camera.