Effect of Photic Injury on the Retinal Tissues

Color Doppler Imaging of Choroidal Circulation in Patients with Asymmetric Age-Related Macular Degeneration

“…Hence, many investigators are trying to identify risk factors for the development of CNV in order to understand the pathophysiology of CNV better and to institute appropriate treatment in good time. There are various reported ocular and systemic risk factors for the development of exudative AMD [27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38]. It has been suggested that drusen type determines the relative risk of CNV formation [4, 5, 7, 8, 35, 42].…”

“…Besides this baseline examination, all patients were examined in order to determine the presence of various systemic and ocular risk factors for the development of CNV [27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38]. The systemic and ocular risk factors considered, based on previously published reports, are presented in table 1.…”

Retinal light toxicity

“…At 3 to 6 months following photic insult, the only remaining evidence of photochemical injury may be a yellowish plaque-like lesion. [94][95][96][97] More recently, high-resolution autofluorescence imaging using an adaptive optics scanning laser ophthalmoscope has been used to examine changes resulting from photochemical injury to the retina. Studies by Morgan et al on macaque retinas showed an immediate decrease in autofluorescence of RPE cells following a 15-min exposure of 568 nm light.…”

“…They described the histologic response to photochemical injury as occurring in three stages: the acute stage occurs within 24 h of the photic insult and is characterized by retinal oedema, RPE pigment disorganization, irregularity of the photoreceptors, and the presence of abnormal pigmentary cells in the subretinal space; the second stage, or reparative stage, occurs approximately 1 week after the initial insult and is characterized by a macrophage response; the third stage, or chronic degenerative stage, can occur weeks to months after the photic injury and is characterized by the proliferation of RPE cells and the formation of a plaque between Bruch's membrane and the outer retina consisting of RPE cells and macrophages. 96,97,[101][102][103] Additionally, work by Postel et al 104 showed the presence of cystoid macular oedema, subretinal nodules of hyperplastic RPE, and atrophy of the nerve fibre and ganglion cell layers. Recent work by Albert et al 105 has shown the development of progressive stages of retinal degeneration and choroidal neovascularization after long-term intense cyclic light exposure in albino rats ( Figure 5).…”

Repair of Retinal Pigment Epithelium and Choriocapillaries after Laser Photocoagulation: Correlations between Scanning Electron, Transmission Electron and Light Microscopy

“…In our previous study, TEM showed that the post-lasering repair process is character ized by the appearance of a morphologically heterogeneous population of RPE cells, some of which resemble macrophages [10]. Other investigators have also reported cytologic variations, including macrophages [21], among regenerated RPE cells after lasering or other damage to the RPE cells [24,25], On the basis of these studies [10,21,24,25] we assumed that there is a correlation between the phenotype of regenerated RPE cells and the regenerated vascular endothelium. All of those observations, however, were based upon reconstruction from thin sections.…”