Altered peripapillary vessel density and nerve fiber layer thickness in thyroid-associated ophthalmopathy using optical coherence tomography angiography

Abstract

Objective: To measure the peripapillary vessel density (VD) and retinal nerve fiber layer thickness (RNFLT) in thyroid-associated ophthalmopathy (TAO) and dysthyroid optic neuropathy (DON) patients using optical coherence tomography angiography (OCTA), and determine their prognostic relevance.

Methods: Forty-three TAO patients with or without DON (82 eyes in total) and 26 healthy subjects (52 eyes) were enrolled. All participants underwent ophthalmology and endocrinology tests. The peripapillary VD in retinal peripapillary capillary layer and RNFLT were analyzed using OCTA images. Multiple linear regression analysis was used to assess the relationship between peripapillary VD /RNFLT and the relevant factors.

Results: The total peripapillary VD and RNFLT were significantly lower in the DON patients compared to the other groups (P < 0.001, 95% confidence intervals), and each quadrant of VD and RNFLT showed similar results except temporal RNFLT. No significant difference was seen between the RNFLT and VD of active non-DON (ANDON), inactive non-DON (NDON) patients and normal control (NC) group. Multivariable linear regression model showed that high IOP is an independent risk factor for lower peripapillary VD and RNFLT (β = -0.465, P < 0.001 and β = -0.343, P = 0.002 respectively).

Conclusion: OCTA parameters are suitable indicators for diagnosing DON. TAO patients with high IOP should be considered at high risk of retinal vessel and nerve fiber layer deterioration. In addition, patients with TAO should be advised to quit smoking since it could affect peripapillary VD and RNFLT.

Keywords: Dysthyroid optic neuropathy; OCTA; Peripapillary vessel density; Retinal nerve fiber layer thickness; Thyroid-associated ophthalmopathy.

Fig. 1

Evaluation of basic information including age a, IOP b, number of affected muscles c of the four groups. (*P < 0.05 between indicated groups)

Fig. 2

Coronal MRI pictures of the four groups. NC group showed no abnormal muscles. a NDON group. b and ANDON group. c showed varying degrees of enlarged extraocular muscles. DON group showed enlarged extraocular muscles and crowded orbital apex (d)

Fig. 3

Evaluation of peripapillary VD a and RNFLT b in the four groups. (* P < 0.05 between indicated groups)

Fig. 4

OCTA images of the four groups. Peripapillary VD and RNFLT of NC group were normal. NDON group showed minor decrease of peripapillary VD and RNFLT. ANDON and DON groups showed obviously diminished peripapillary VD