Men who have a pre-existing diagnosis of hypothyroidism may be at greater risk of developing open-angle glaucoma, says a study in the September Ophthalmology.1
The study took place at the Veterans Affairs Medical Center in Birmingham, Ala., between 1997 and 2001. It compared 590 men (mean age of 70), who were newly diagnosed with glaucoma, to 5,897 age-matched control subjects without glaucoma.
Specifically, they used patient information from the centers data files containing demographic, clinical and medication information. Patients who had a glaucoma diagnosis before the observation period of the study were excluded.
Results showed that the glaucoma subjects were significantly more likely to have pre-existing hypothyroidism than the controls after adjusting for conditions associated with glaucoma such as migraines, hypertension, diabetes, lipid metabolism disorders, as well as arterial, cerebrovascular and cardiovascular disease.
The share of glaucoma patients who had a pre-exisitng diagnosis of hypothyroidism was 6.44% vs. 3.97% of the control subjects. Also, hypertension, diabetes, migraines and lipid metabolism disorders were significantly more frequent in the glaucoma subjects than in the controls. However, there was no difference in cases of arterial, cerebrovascular and cardiovascular between the two groups.
Still, the researchers admit the study had the following limitations:
The subjects were all male. Women were excluded because they made up a small portion of the hospitals population.
Because the diagnosis of glaucoma was defined by ICD-9CM codes, there may have been miscoding or possible misdiagnosis. (The researchers concede, however, that there is little reason to suspect misclassification because hypothyroidism is not an established glaucoma risk factor.)
A bias could be a potential concern, as the identification of glaucoma was based on the first visit when the glaucoma was diagnosed.
The researchers were unable to adjust for racial differences between subjects and controls, because such information was lacking.
1. Girkin CA, McGwin G Jr, McNeal SF, et al. Hypothyroidism and the development of open-angle glaucoma in a male population. Ophthalmology 2004 Sep;111(9):1649-52.