Abstract
Purpose:
Extraocular muscle enlargement and orbital fat expansion in thyroid-associated ophthalmopathy (TAO) may result in proptosis, diplopia, compressive optic neuropathy and visual acuity impairment. Although the orbital and histopathological structural changes associated with TAO are well documented, no significant change in retinal and/or nerve fiber layer (RNFL) thickness has been demonstrated. Optical coherence tomography (OCT) is a noninvasive imaging technology that accurately assesses RNFL thickness. Aim: To compare retinal and peripapillary RNFL thickness values in TAO patients with those of normal subjects and to assess the correlation between the severity of the orbital disease and the changes observed in macular and RNFL thickness.
Methods:
Twenty-one patients with TAO (mean age 44.1 years) and 41 healthy controls (mean age 42.9 years) were evaluated. The participants underwent complete ophthalmological and OCT examinations (including measurements of macular and peripapillary RNFL thicknesses).
Results:
The inner macula was significantly thinner (270.4±17.27 μm) in 40 eyes of 21 patients compared to 281.79±15.2 μm in 63 eyes of the 41 controls (p=0.001). The average RNFL thickness was significantly greater in the TAO group (n=42, 110.06±33.3 μm) compared to the controls (n=73, 96.25±9.42 μm) (p=0.013). The superior, inferior and nasal quadrant RNFL thicknesses were significantly greater in the TAO group (136.7±45.73, 137.95±35.03, and 99.38±65.85, respectively) compared to controls (118.47±14.25, 125.52±13.55, and 71.91±13.95, respectively). There was also a correlation between the above-mentioned changes in RNFL thickness and the clinical severity of the orbital disease.
Conclusions:
Eyes of patients with TAO have a thinner macula and a thicker peripapillary RNFL compared to healthy controls, as demonstrated by OCT. There is also a correlation between the clinical severity of the disease and these changes on imaging. Retinal thinning may be secondary to mechanical compression on the retina by orbital contents. OCT may serve as a noninvasive tool for the diagnosis and follow-up of TAO.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
631 orbit •
629 optic nerve