Abstract
Purpose:
Pigmentation may play a role in the pathogenesis of age-related macular degeneration (AMD). As DOPA is a precursor of melanin, we hypothesized that L-DOPA, used in the treatment of Parkinson's disease, may affect the development of AMD.
Methods:
Using International Classification of Diseases, Ninth Revision codes (ICD-9), we retrospectively compared the age of first diagnosis of AMD between patients taking or not taking L-DOPA, utilizing cohorts of patients from two Marshfield Clinic Research databases (including 20,000 and 17,000 patients) and the insurance claim-based Truven MarketScan databases from the years 2007-2011 (approximately 87 million outpatient individuals). In addition, a retrospective cohort of 2,006 AMD patients was reviewed, and a prospective cohort of 47 Parkinson's disease patients treated with L-DOPA were given comprehensive eye examinations; both cohorts were at Medical College of Wisconsin.
Results:
In the two Marshfield Clinic samples, the mean ages of first AMD diagnosis in patients not treated with L-DOPA were 71.2 years and 71.1 years, and the mean ages of first AMD diagnosis in patients treated with L-DOPA were 79.3 years and 79.3 years respectively (p=0.0017). From the MarketScan databases, the mean age at first AMD diagnosis in patients not treated with L-DOPA (N=679,574) was 71.4 years, and the mean age of first AMD diagnosis in patients treated with L-DOPA (N=12,387) was 79.3 years (p<0.001). Utilizing the subpopulation of patients with ophthalmic ICD-9 codes (N=15,215,458), it was found that after controlling for age and gender, patients with a prescription history of L-DOPA were significantly less likely to have a diagnosis of AMD (OR=0.78;CI=0.76-0.80;P<0.001). In the retrospective cohort of 2,006 AMD patients, only 19 were using L-DOPA, and all 19 were diagnosed with AMD prior to initiating L-DOPA. In the prospective cohort of 47 Parkinson's disease patients, 7 patients with early AMD were diagnosed, which is fewer than expected for this age group.
Conclusions:
Collectively, these results suggest an inverse relationship between L-DOPA treatment and incidence of AMD. If these results can be confirmed, L-DOPA and its intermediaries may provide future drug targets in the prevention or treatment of AMD.