Thyroid eye disease (TED) often causes the eye to bulge forward, which leads to other ocular complications. Increased IOP as a result of swelling may also damage the optic nerve. A recent study evaluated the changes in the retinal nerve fiber layer (RNFL) and ganglion cell layer/inner plexiform layer (GCL/IPL) with the severity of TED and found that subclinical optic neuropathy may progress in those with moderate-to-severe TED.

The study included 145 eyes of 75 patients with TED and a control group of 70 eyes of 35 patients. The TED eyes were divided into mild (n=35), moderate-to-severe (n=42) and severe (n=68). The researchers measured RNFL and GCL/IPL by OCT, clinical activity score, best-corrected visual acuity (BCVA), IOP, proptosis and mean deviation on visual fields.

Among the three TED subgroups, clinical activity scores were significantly different. The researchers observed significantly higher IOP and proptosis in the severe and moderate-to-severe groups compared with the mild group. Mean deviation and BCVA were significantly worse in the severe group compared with the other two. Severe cases also had the thinnest GCL/IPL. Mean RNFL thickness was significantly different between the moderate-to-severe eyes and sdevere group.

The researchers noted that mean GCL/IPL thickness demonstrated a significant correlation with mean deviation and visual acuity; whereas, mean RNFL thickness showed no significant correlation with mean deviation.

They concluded that patients with moderate-to-severe TED might experience a progression of subclinical optic neuropathy. Additionally, they noted that their OCT measurements of RNFL and GCL/IPL were useful for detecting early optic nerve changes. They wrote that GCL/IPL thinning may warrant more follow-ups and earlier decompression surgery.