Abstract
Purpose: :
Age related macular degeneration (AMD) is a major cause of legal blindness in elderly people. There are multiple theories of the aetiology of AMD including senescence, ischemia, oxidative stress and genetic factors. There is also increasing knowledge of the events causing AMD. The role of the posterior hyaloid in the pathogenesis of neovascular AMD is not yet examined. It was aim of this study to compare the behaviour of the posterior hyaloid in neovascular and non neovascular AMD.
Methods: :
This prospective trial included patients over 55 years suffering from AMD. According to the morphology of the lesion they were assigned to one of two subgroups (neovascular AMD: group1, non neovascular AMD: group2). Besides clinical examinations OCT scans were performed including 6 radial lines through the fovea, additional lines through the upper and lower arcade and radial lines through the optic disc as well as B–scan ultrasound.
Results: :
50 eyes with neovascular AMD and 57 with "dry" AMD of 107 eyes enrolled could be included. 33.6% of the patients were male, 66.4% were female. The mean age was 74 years (range:55–89 years). There was equal distribution of gender and age in both subgroups. 40% of the eyes in subgroup 1 and 68.4% of the eyes in subgroup 2 had a complete detachment of the posterior hyaloid in ultrasound. A partially detached posterior hyaloid with a tight adhesion in the centre surrounded by a detached vitreous surface was detected in the OCT in 38% of subgroup1 and 7% of subgroup2.
Conclusions: :
There was a significant higher incidence of complete vitreous detachment in eyes with "dry" AMD. There was a significant higher incidence of a central adhesion surrounded by a flat detachment of the posterior hyaloid in neovascular AMD in the OCT. Pathogenetic factors of neovascular AMD might cause these tight adhesions. However, the attached posterior vitreous might be a possible pathogenetic factor by itself. Vitreoretinal traction or the more intense exposure to cytokines or free radicals in the vitreous gel could be etiologic factors.
Keywords: age-related macular degeneration • vitreous • choroid: neovascularization