Two disease processes affect ocular surface in Graves’ orbitopathy

This study's authors analyzed both clinical and confocal changes inthe ocular surface of patients with active and inactive Graves' orbitopathy. It's the first study to use confocal microscopy to make a quantitative evaluation of corneal alternations in Graves' orbitopathy.

Subjects were 26 consecutive patients with Graves' orbitopathy and 20 age- and gender-matched controls. The authors evaluated their symptoms using the Ocular Surface Disease Index, tear break-up time, fluorescein (corneal) and lissamine green (conjunctival) staining, corneal apex sensitivity and Shirmer's test. The corneal apex was examined with confocal microscopy in order to investigate the number and morphology of epithelial and stromal corneal cells and sub-basal nerves.

Eleven of the 26 Graves' orbitopathy patients (43 percent) were found to have active Graves' orbitopathy. There were statistically significant differences between patients and controls in all evaluated parameters except for corneal sensitivity and nerve reflectivity. Dry eye features were, as expected, more prevalent among Graves' orbitopathy patients compared to controls. This can be explained mainly by tear film instability, mild lacrimal hyposecretion and increased evaporative mechanisms, due to increased corneal exposure related to proptosis, lagophthalmos, lid retraction and possibly altered blink mechanics. There were significant differences in cell densities at all layers between patients and controls. Except for superficial epithelia, for which controls had higher densities, Graves' orbitopathy patients had more basal epithelium and anterior and posterior stromal cells. In particular, there were significantly more activated highly reflective stromal keratocytes in active vs. inactive Graves' orbitopathy patients.

They conclude that ocular surface inflammation in these patients appears to be affected by both dry eye and by the systemic disease itself.