Purchase this article with an account.
Michael Quigley, Ian Powell, Walter Wittich; AGE-RELATED MACULAR DEGENERATION: BOTH MYOPIA AND SUNGLASSES DECREASE RETINAL LIGHT DOSE WHICH MAY EXPLAIN THEIR PROTECTIVE EFFECT. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2429.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The Beaver Dam and POLA eye studies reported that the wearing of hats and sunglasses significantly decreased the risk of some early AMD lesions. Myopia also decreases AMD risk. We hypothesize that myopia decreases retinal light dose as do hats and sunglasses which may explain its protective effect.
We created a simple one-surface schematic eye and use ray-tracing, spectacle power, vertex distance, corneal power, anterior chamber depth and axial length to calculate relative light flux through the pupil and resultant image size on the retina in a randomly selected group of 71 eyes from the Reykjavik Eye Study. Given that pupil size is known to be unaffected by refractive error, the retinal light dose (RLD) or photons/mm2 can be calculated and compared to other eyes. The results were confirmed in a computer-based optical design and ray-tracing software ( Optisoft II).
RLD is inversely proportional to axial length. A 21 mm axial length eye would always be receiving 1.8X more photons/mm2 than a 27mm axial length eye. Removing a pair of commercial sunglasses would increase retinal light dose by 1.7X-5X depending on the filtering capacity of the glass.
RLD is inversely proportional to axial length as is AMD risk. The parsimonious explanation for our finding is that myopia exerts its protective effect on the retina in AMD in the same way sunglasses do: by decreasing retinal light dose.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
This PDF is available to Subscribers Only