Cataract Removal and Alzheimer's Disease
Condition: Cataracts; Alzheimer's Disease
MeSH terms: Alzheimer Disease; Cataract
Study type: Interventional

Summary: 
      Two very common aging-related diseases in older adults are Alzheimer's disease (AD) and
      cataracts. In elderly adults, these two diseases frequently occur in the same person.
      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 visual
      performance and for reducing accidents and falls. However, it has been the experience of the
      ophthalmologists, and others in the field, that patients, caregivers, and primary care
      doctors are reluctant to proceed with cataract surgery once an individual is given the
      diagnosis of AD. It is thought that cataract surgery will not improve the AD patient's
      quality of life, vision, and cognition. The investigators have designed this study to
      determine whether or not this is true.
    

Detailed description: 
      In this project, we propose to test the following clinical hypothesis, while addressing the
      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 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.
    

Intervention name(s): Immediate Cataract Surgery
Intervention type(s): Procedure
Intervention description(s): Cataract surgery, as part of standard of care, will be performed on 1/2 of the group under investigation.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: Alzheimer's Disease; vision impairment; cataract; quality of life; retinal nerve fiber layer