Contrast sensitivity function and extraocular muscles thickness in patients with early stage Graves’ ophthalmopathy

Abstract

The aim of this study was to determine the value of the ultrasonography measurements of extraocular muscles in early stage Graves' ophthalmopathy (GO) and compare the contrast sensitivity function in patients and healthy control eyes. We examined 25-65 years old patients with early stage GO (20 eyes) and age matched healthy subjects (16 eyes). All participants underwent complete ophthalmic examination. The measurements of rectus extraocular muscles were performed by A/B mode Mentor^TM Advent ultrasonic diagnostic imaging system. We evaluated thickness (mm) of each extraocular muscle, compared with normal values, calculated the sum of the muscles thickness in a given eye. Contrast sensitivity (CS) was assessed by a Ginsburg Functional Acuity Contrast Test (FACT, Vision Sciences Research Corp.) chart, under day and night lighting conditions at five spatial frequencies (cpd). Inferior rectus muscle enlargement (thickness ≥ 3,6 mm) was found in 14 eyes (70 percent) of patients, p=0.008. Patients CS results differ significantly  from those of the control group (p<0.05; power 0.65-0.87), except the 6 cpd range under night lighting conditions (p=NS). The relation between the sum of the muscles thickness and CS thresholds are pronounced for the medium (6cpd) and high (12cpd) spatial frequency ranges (Spearman correlation coefficient 0.6, p=0.032 and 0.7; p=0.012, respectively). Even if visual acuity was intact and proptosis was not pronounced, CS impairment and extraocular muscles enlargement were detected in patients with early stage of GO

http://dx.doi.org/10.5755/j01.u.66.3.658