Two very common aging-related diseases in older Americans are Alzheimer's disease (AD) and cataracts. In elderly adults, these two diseases frequently occur in the same person, thereby producing a state of multiple morbidities. Although a cure for AD is currently unavailable, cataracts can be effectively treated with surgery in most people. The removal of cataracts has documented benefits for basic vision and for reducing accidents and falls. However, the value of cataract removal in patients already affected with AD is uncertain, and many ophthalmologists, geriatricians, and care-givers do not consider cataract surgery to be appropriate in this patient group. In this project, we propose to test the following clinical hypothesis, while addressing the a primary and two secondary Specific Aims: Hypothesis. Cataract removal produces measurable benefits in vision, perception, independent function, and quality of life in patients with co-morbid Alzheimer's disease. Primary Specific Aim. To determine the effects of cataract removal on visual acuity, spatial contrast sensitivity, vision dependent functions, visual information processing, and quality of life in patients with Alzheimer's disease. Secondary Specific Aims. 1. To delineate the baseline characteristics of those patients who benefit most from the surgical intervention. 2. To assess the thickness of the retinal nerve fiber layer (RNFL) with optical coherence tomography (OCT) in large samples of AD patients classified with mild or moderate dementia to determine if the thickness of the RNFL is associated with dementia severity, visual performance measures, and other patient characteristics. The study is designed as a Randomized Controlled Trial (RCT) with two cohorts of AD patients in a longitudinal investigation. Each person will be evaluated periodically over a 6 month period. All participants will be diagnosed with visually significant bilateral cataractous lens. The cohorts will be established by randomly assigning patients to either the immediate or the (optional) delayed surgery group. Patients will be stratified by AD severity (CDR mild or moderate) and cataract severity (LOCS 1-2 or 3-4) prior to being randomized. Comparisons between and within groups will test the change over time in vision, visual information processing, and quality of life associated with or without the removal of cataracts. The RNFL thickness of each person will be evaluated with optical coherence tomography (OCT). The thickness of the RNFL will be compared across dementia severity levels. Each consented participant will have a consenting study partner who may be referred to as a Research Partner, and who will often be the participant's caregiver. The latter will help to assure protocol adherence by the AD participants and will provide information about behavioral symptoms, activities of daily living, and amount of resources used. The study will demonstrate the clinical efficacy of cataract removal as a direct intervention to potentially improve the visual and cognitive functions, and the quality of life in persons diagnosed with AD.
The study will yield information that will affect significantly the treatment options offered to AD patients with cataracts. In addition, the study will add important information regarding the impact of sensory impairment on higher cognitive functioning.
| Narasimhalu, K; Ang, S; De Silva, D A et al. (2009) Severity of CIND and MCI predict incidence of dementia in an ischemic stroke cohort. Neurology 73:1866-72 |
