Ophthalmology/Eye Institute

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 Department of Ophthalmology Case Studies

 

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Discussion:

Differential Diagnosis-
The appearance of bilateral soft drusen and an area of subretinal hemorrhage in the left eye is consistent with the diagnosis of wet age-related macular degeneration. The subretinal hemorrhage is most likely due choroidal neovascularization (CNV). Other causes of subretinal hemorrhages and decreased vision include retinal arterial macroaneurysms, diabetic retinopathy, hypertensive retinopathy, valsalva retinopathy and other causes of CNV (high myopia, angioid streaks, presumed ocular histoplasmosis or trauma).

Definition-
Age-related macular degeneration (AMD) is a degenerative retinal disease. Two main types exist although many classification schemes are in use. Dry AMD is characterized by the appearance of hard or soft drusen and/or areas of retina pigmented epithelium (RPE) loss or hypertrophy. Large areas of RPE loss, termed geographic atrophy, are mainly responsible for decrease vision in this type of AMD. Wet AMD, comprising 15% of all AMD cases, results in severe central visual loss if not treated promptly. In wet AMD pathologic choroidal neovascular membranes develop under the retina, RPE or both resulting in destruction of retinal architecture and formation of fibrovascular scars and vision loss. Risk factors for the development of AMD are genetic and environment and include mutations in the complement factor H gene, family history of AMD, age and white race. Many associations with other diseases exist including smoking and hypertension. High risk populations for progression from dry to wet AM include those with large drusen, many intermediate-sized drusen, non-central geographic atrophy, or advanced AMD in the other eye.

Examination-
Patients with AMD are recommended to monitor their vision, each eye separate, with the Amsler grid (a series of horizontal and vertical lines forming a grid of squares). Appearance of a blind spot or waviness of the straight lines (metamorphopsia) could signal alterations in the photoreceptor layer and should be evaluated for the development of wet AMD. Fluorescein angiogram (FA) is the gold standard to identify areas of abnormal vasculature within or under the retina consistent with CNV. Typical findings include areas of hyperfluorescence +/- leakage. The optical coherence tomography (OCT) technique allows for identification of intra or subretinal fluid in the macula. In patients with CNV this corresponds to extravasation of fluid from leaky capillaries. Response to therapy is seen with improvement of vision, decrease of fluid in OCT and decrease of leakage and/or hyperfluorescence in FA.

Treatment-
The age-related eye disease study (AREDS) vitamin formulation is recommended for patients with severe forms of dry AMD. These vitamins (a specific combination of vitamins A, C, E, zinc and copper) have been shown to decrease the progression of AMD. For vision-threatening wet AMD, the most effective therapy is anti-vascular endothelial growth factor (VEGF) agents. Prompt treatment can stabilize or improve visual acuity in 2/3 of patients. Other less successful treatment modalities include photodynamic therapy and laser photocoagulation.
 

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