Authors: Mark K. Lukewich, Matthew B. Schlenker, Jonathan A. Micieli
Author Disclosure Block: M.K. Lukewich: None. M.B. Schlenker: None. J.A. Micieli: None.

Abstract Body:

Purpose: Neuro-ophthalmologists may discover homonymous thinning of the optical coherence tomography (OCT) macular-ganglion cell complex (GCC) without significant visual field defects in the workup of patients with suspected optic neuropathies or visual field defects. The differential diagnosis for this finding remains unknown. The goal of this study was to determine the causes of homonymous thinning of the OCT macular-GCC without significant visual field changes.

Study Design: A retrospective chart review was performed on 1000 consecutive patients that underwent OCT retinal nerve fiber layer (RNFL) and macular-GCC with Humphrey visual fields.

Methods: Patients were included in the study if they had high quality OCT scans, MRI brain, Humphrey visual fields and homonymous macular-GCC atrophy without significant visual field changes. A normalized asymmetry score (NAS) and the degree of bow-tie atrophy were quantified.

Results: A total of 6 patients, 3 females and 3 males, with a mean age of 40.3 (range 27 to 57) years were included in the study. Homonymous OCT macular-GCC thinning was secondary to demyelination of the optic tract in 4 patients (3 with multiple sclerosis and 1 with clinically isolated syndrome) and traumatic brain injury (TBI) in 2 patients. Three patients with demyelinating disease had a documented prior homonymous visual field defect that resolved. One TBI patient experienced a subjective visual field defect, but did not have this documented. There was a higher mean NAS among TBI patients (0.33) compared to those with demyelination (0.20, p=0.07). No significant difference in the degree of bow-tie atrophy was observed between groups (TBI 0.49, demyelination 0.50, p=0.55).

Conclusions: Homonymous thinning of the OCT macular-GCC with essentially normal visual fields is mainly a result of previous demyelination involving the optic tract and TBI. OCT macular-GCC represents a novel method for establishing previous optic tract involvement in multiple sclerosis, which can help in establishing dissemination in time and space.