Retinal damage secondary to chronic light exposure

Abstract

The effect upon the retina of exposure to large fields of bright visible light has been evaluated. The thresholds for permanent retinal damage for four hour exposures in rhesus monkeys have been established for white light, and laser lines of 514.5 nm, 488 nm, 457.9 nm, and 590 nm. The damage has been evaluated by ophthalmoscopy, electroretinography and light and electron microscopy. The shortest wavelength light (457.9 nm) is more effective in causing damage, particularly histological damage, which is spread throughout the fundus and throughout the retinal layers. Functional damage shown by the electroretinogram follows a different action spectrum without the increased effect in the blue. There appears to be more than one mechanism for retinal damage in chronic light exposure, and at least one mechanism is not dependent solely upon the visual pigment and the pigment epithelium. Thresholds of permanent damage appear to be within one or two log units of light levels encountered in the normal visual environment. Newer data suggest that this damage is additive. Daily one hour exposures for four days produce damage equivalent to a single four hour exposure at the same retinal irradiance.

In vivo dynamics of retinal injury and repair in the rhodopsin mutant dog model of human retinitis pigmentosa

“…Two exposure intensities estimated to achieve lower (0.1 mW⅐cm Ϫ2 ) and higher (1 mW⅐cm Ϫ2 ) retinal irradiances were used; the doses were 6 and 60 mJ⅐cm Ϫ2 , respectively. The lower dose was 1,500-to 6,000-fold less than retinal damage thresholds for white or medium-wavelength light in different species (16)(17)(18). In another experiment, dogs underwent ''stereo'' fundus photography by an experienced fundus photographer using a conventional camera (FF4, ZeissMeditec, Dublin, CA) at settings typically used in a human eye clinic (flash intensity, 60 Ws; observation͞focusing, 2).…”

Oxidative Stress Induced Damage of the Human Retina: Overview of Mechanisms and Preventional Strategies

“…That is why this group assumes other mechanisms of electron excitation and followed radical damage (Ham et al, 1976). On the other hand, other authors demonstrate that also low dosages of light can induce significant amounts of radicals (Lawwill et al, 1977). A cumulative damage occurs in the retina during this kind of irradiation.…”

“…Here, fractionated doses of light are acting with higher intensity then comparable -although continuous -actions. This effect does not occur if the retina is allowed to regenerate in a longer dark period (Noell et al, 1966;Ham et al, 1979;Lawwill et al, 1977;Tsò et al, 1972).…”

Combatant Eye Protection: An Introduction to the Blue Light Hazard

“…The LED spectral distribution in the Figure 4 reveals major spectral output peaks at or slightly below 400 nm, dipping into the near UVR range. Extended retinal exposures to visible blue light at wavelengths below 550 nm produced actinic or photochemical effects at retinal wavelengths and irradiancies too low to produce thermal effects (Friedman and Kuwabara, 1968;Harwerth and Sperling, 1984;Lawwill, Crockett, and Currier, 1977). However, there is no sharp line of demarcation between thermal and actinic effects.…”