Abstract
Abstract: :
Purpose: Associations between thyroid medication use and age–related macular degeneration (AMD) were reported by the Beaver Dam Eye Study (increased risk of early AMD) and the Age–Related Eye Disease Study (increased risk of geographic atrophy (GA)). We investigated the association of thyroid function and AMD in a large, nationally representative sample. Methods: Participants in the National Health and Nutrition Examination Survey (NHANES) III submitted to an interview and assessments of serum thyroxine (T4), thyroid–stimulating hormone (TSH), antimicrosomal antibodies (TMAb), and antithyroglobulin antibodies (TgAb). Non–mydriatic 45° color fundus photographs were taken for persons ≥ 40 years and graded for presence/absence of hard and soft drusen, retinal pigment epithelium (RPE) degeneration, hyperpigmentation, GA, and exudative changes (subretinal serous detachment, fibrous scarring, or hemorrhage). Thyroid function was defined based on laboratory values: hyperthyroid (TSH <0.1 ug/dL), hypothyroid (TSH >4.5 ug/dL), or TgAb– or TMAb–positivity ((TgAb+, TMAb+). SUDAAN was used to appropriately assign weights to each participant based on the NHANES multistage probability sampling scheme. Results: 10,181 persons ≥ 40 years participated in the NHANES III examination; 8603 had gradable fundus photographs. 144 (1.7%) had RPE degeneration, 185 (2.2%) had hyperpigmentation, 32 (0.4%) had GA, and 24 (0.3%) had exudative AMD. 149 participants with gradable photos (1.9%) were hyperthyroid, 570 (7.4%) were hypothyroid, 1598 (19.9%) were TgAb+ or TMAb+, and 755 (9.4%) were TgAb+ and TMAb+. Most associations between AMD lesions and thyroid measures were weak (age–adjusted odds ratios [aOR] >0.8 and <1.25) and not statistically significant. However, TMAb+ persons were less likely to show pigment–related AMD changes (hyperpigmentation, RPE degeneration, or GA) (aOR=0.71, 95% CI: 0.48–1.05, p=0.08) and more likely to show exudative AMD changes (aOR=3.53, 95% CI: 1.00–12.43, p=0.05). Hyperthyroid persons had an increased risk of pigment–related AMD changes (aOR=2.84, 95% CI: 0.91–8.80, p=0.07) and an increased, statistically insignificant risk of exudative AMD (aOR=4.38, 95% CI: 0.45–43.0, p=0.19). Hypothyroid persons were less likely to have RPE degeneration (aOR=0.30, 95% CI: 0.12–0.78, p=0.01); none had exudative AMD. Associations did not change after adjustment for gender, use of thyroid medication, or estrogen hormone replacement therapy use. Conclusions: Further investigation of the association of thyroid function and AMD in other cohorts may provide insights.
Keywords: age–related macular degeneration • clinical (human) or epidemiologic studies: risk factor assessment • autoimmune disease