Cataract Removal and Alzheimer's Disease

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.

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.

Eligibility Criteria:
Inclusion Criteria:

* age 50 and older
* clinical diagnosis of possible/probable Alzheimer's disease, or other type of dementia, mild (CDR-1), moderate (CDR-2), or severe (CDR-3)
* at least 1 visually significant cataract
* no ocular pathology
* psychotropic drug must be with stable dosage for 30 days

Exclusion Criteria:

* history of cataract removal
* history of visually significant retinal, or optic nerve abnormalities
* informed consent cannot be obtained from either subject or their research partner
* subject shows evidence (in preoperative testing) of unstable cardiac or pulmonary function
* history of uncontrolled diabetes or hypertension
* history of stroke in areas known to affect cognition
* life expectancy of less than 1 year
* Down's Syndrome