Mehtap Cakir1, Banu Turgut Ozturk2, Elif Turan1, Gulsum Gonulalan1, Ilker Polat3, Kemal Gunduz4. 1. Division of Endocrinology and Metabolism, Konya Necmettin Erbakan University, Konya, Turkey. 2. Department of Ophthalmology, School of Medicine, Selcuk University, Konya, Turkey. 3. Departments of Internal Medicine, Konya Necmettin Erbakan University, Konya, Turkey. 4. Departments of Ophthalmology, Meram School of Medicine, Konya Necmettin Erbakan University, Konya, Turkey.
Abstract
BACKGROUND: Thyroid hormone has been shown to control retinal cone opsin expression, the protein of color vision, in adult rodents. OBJECTIVES: The aim of this study was to evaluate the effect of hypothyroidism on color contrast sensitivity in adult overt hypothyroid patients. METHODS: Thirty-eight overt hypothyroid (31 females, 7 males) subjects and 20 euthyroid (16 females, 4 males) controls were studied prospectively. Color vision examination was performed by Chromatest, a software program analyzing the tritan (blue-yellow) color contrast threshold (tritan CCT) and protan (red-green) color contrast threshold (protan CCT). Color contrast sensitivity analyses of hypothyroid subjects were performed on admission and after L-thyroxine treatment when biochemical euthyroidism was achieved. RESULTS: After a median period of 90 (90-210) days, 24 (19 females, 5 males) patients were euthyroid and eligible for a second color vision examination. Baseline tritan CCT and protan CCT values were significantly higher in the hypothyroid group compared to euthyroid controls, which clinically translates into impaired color contrast sensitivity (p < 0.001 and p < 0.001, respectively). There was a significant decrease in tritan CCT (p = 0.002) and protan CCT (p < 0.001) values in the hypothyroid group after euthyroidism was achieved, which denotes improvement in color contrast sensitivity. CONCLUSIONS: It is a novel finding of the current study that color contrast sensitivity is impaired in hypothyroidism and significantly improves after euthyroidism is achieved.
BACKGROUND: Thyroid hormone has been shown to control retinal cone opsin expression, the protein of color vision, in adult rodents. OBJECTIVES: The aim of this study was to evaluate the effect of hypothyroidism on color contrast sensitivity in adult overt hypothyroidpatients. METHODS: Thirty-eight overt hypothyroid (31 females, 7 males) subjects and 20 euthyroid (16 females, 4 males) controls were studied prospectively. Color vision examination was performed by Chromatest, a software program analyzing the tritan (blue-yellow) color contrast threshold (tritanCCT) and protan (red-green) color contrast threshold (protan CCT). Color contrast sensitivity analyses of hypothyroid subjects were performed on admission and after L-thyroxine treatment when biochemical euthyroidism was achieved. RESULTS: After a median period of 90 (90-210) days, 24 (19 females, 5 males) patients were euthyroid and eligible for a second color vision examination. Baseline tritanCCT and protan CCT values were significantly higher in the hypothyroid group compared to euthyroid controls, which clinically translates into impaired color contrast sensitivity (p < 0.001 and p < 0.001, respectively). There was a significant decrease in tritanCCT (p = 0.002) and protan CCT (p < 0.001) values in the hypothyroid group after euthyroidism was achieved, which denotes improvement in color contrast sensitivity. CONCLUSIONS: It is a novel finding of the current study that color contrast sensitivity is impaired in hypothyroidism and significantly improves after euthyroidism is achieved.
Entities:
Keywords:
Color vision; Cone; Hypothyroidism; Opsin; Thyroid
Authors: Cristiano N Pessôa; Leticia A Santiago; Diana A Santiago; Danielle S Machado; Fernando A F Rocha; Dora F Ventura; Jan Nora Hokoç; Carmen C Pazos-Moura; Fredric E Wondisford; Patricia F Gardino; Tania M Ortiga-Carvalho Journal: Invest Ophthalmol Vis Sci Date: 2008-05 Impact factor: 4.799