Correlation Between Visual Acuity Measurements, Quality of Life and Morphological Parameters in Wet AMD Patients

3.1 Background and Rationale AGE-RELATED MACULAR Degeneration (AMD) is the leading cause of blindness among European descended people older than 65 years.

Today, the average life expectancy in developed nations is over 80 years and climbing. And yet, the quality of life during those additional years is often significantly diminished by the effects of age-related, degenerative diseases, including age-related macular degeneration (AMD) Central-field loss (CFL) is often a consequence of macular degeneration, necessitating the use of peripheral vision for reading That means that AMD affects the central vision, resulting in central scotomas and therefore the patients have problems with near distance activities like reading while the peripheral visual field is kept preserved.

AMD is a gradually progressive disease that evolves through stages into severe central vision loss. The earliest signs of AMD involve the appearance of extracellular deposits (drusen), sub-retinal deposits of oxidized lipids and proteins beneath the retinal pigment epithelium (RPE), and variable amounts of visible clumps of pigment in the macula. In the intermediate stages of AMD, drusen become larger and pigmentary changes are more severe. In the advanced stages, patients develop either sub-retinal choroidal neovascularization (the exudative or "wet" form of AMD) or the non-neovascular "dry" form of AMD. The dry form of AMD is characterized by sharply demarcated uni- or multi-focal regions of dysfunctional macula, termed geographic atrophy (GA). The GA patches gradually enlarge to involve the RPE and the corresponding neurosensory retina and choriocapillaris layer of the choroid. These progressive and irreversible changes ultimately cause permanent loss of central (macular) vision.

Geographic atrophy (GA) may cause significant compromise of visual function, even when there still is good visual acuity (VA), because of parafoveal scotomas and foveal function abnormalities antedating visible atrophy AMD is a multifactorial disease with largely unknown pathophysiology. It is believed to be caused by cumulative damage over a lifetime leading to progressive deterioration of the RPE, Bruch's membrane and Choriocapillaris-choroid complex (key players in maintaining retinal function), followed by photoreceptor cells damage. However, the locus of primary damage still remains unclear. Identified pathogenic mechanisms to date include a range of genetic and environmental factors related to primary RPE senescence, oxidative stress, alterations in the complement pathway, increased inflammation, changes in the balance of growth factors, and excessive lipofuscin accumulation. Areas of GA are associated with absolute scotomas. Thus, for a period of years, many patients with GA have good VA because of foveal preservation but are limited by the scotomas surrounding the fovea. For example, a patient may have VA of 20/40 or better, but be unable to fit more than a few letters of a word or a full face in the seeing foveal region .Often multiple central scotomas with very small islands of preserved VA, allow the patient to read single optotypes but not the whole word Visual acuity is the most widely used measure of macular function in clinical trials and clinical practice. However, reading ability is an important component of vision function. Reading difficulty diminishes quality of life . Improvement in reading performance is one of the main objectives for elderly low-vision patients ETDRS often does not reflect the reading problems of the patient which are essential in daily life. High contrast distance acuity is not the only relevant measure of visual function in relation to the perceived visual performance of a patient with macular disease (Hazel et al. 2000).

The visual impairment experienced by many patients with age-related macular degeneration (AMD) has been found to affect their ability to perform usual activities, which cause psychological distress, and limit their participation in social events. PROs of visual function provide a more comprehensive evaluation of the impact of, and the effects of treatment for AMD Progression of dry AMD can be slowed in many patients through dietary supplements while visual loss from wet AMD is treated with intravitreal administration of anti-vascular growth factor Therefore there is the need to find a better outcome parameter. The primary purpose of the study will be to evaluate if there is a correlation between self-reported reading difficulties and new near vision testing instrument results and secondarily to establish how strong self-reported reading difficulties are-correlated to functional and morphological parameters. To also evaluate how strong the standard distance visual acuity measurements (ETDRS) are correlated to further functional and morphological parameters.

The study could provide a basis to find and include outcome measures which are correlated better with quality of life than ETDRS distance VA for further AMD trials.