Changes in the Ocular Parameters of Patients with Graves' Disease after Antithyroid Drug Treatment

To find the differences in ocular axial length, keratometric measurements, and intraocular lens (IOL) power in patients with Graves' disease (GD) after treatment with a thionamide antithyroid drug (ATD), methimazole. The medical charts of 28 patients (4 males and 24 females; mean age: 47.2 ± 21.2 years) were studied. Each patient was examined twice using an IOL Master Device and keratometry at the first visit (before ATD treatment) and after 1 month of ATD treatment. The IOL power was calculated for each patient using the Hoffer Q, SRK-2, and SRK/T formulas according to axial length. After 1 month, the axial length increased (right and left eyes: < 0.001 and = 0.05, respectively). Based on keratometry, changes in the horizontal and vertical optical power [in diopters (D)] were not statistically significant. However, the IOL power changed after 1 month of ATD treatment in 64.3% of the patients. In 14 patients (50%), there was a 0.5-1.0 D IOL power decrease in single eyes; in two patients (7.1%), an IOL power decrease of 0.5-1.0 D in both eyes; and in two patients (7.1%), a 0.5 D IOL power increase in single eyes. The calculated IOL power values were lower after ATD treatment (right and left eyes, = 0.010 and = 0.018, respectively). The IOL power changed in 64.3% of GD patients after ATD treatment. Therefore, avoiding cataract surgery at the early stage of ATD treatment would be appropriate for selecting a more accurate IOL power.