Purpose
Our purpose is to provide a retrospective analysis of ganglion cell layer (GCL) and retinal nerve fiber layer (RNFL) thickness using spectral domain optical coherence tomography (SD-OCT) in patients with homonymous visual field loss from post-geniculate disease.
Methods
Clinic charts from January 2010 to October 2013 of patients with a CPT code for homonymous hemianopsia were reviewed. Out of 222 patients, 22 had undergone SD-OCT. After excluding five patients with a diagnosis of glaucoma, 17 patients remained. For GCL, the combined thickness of the two left sextants (nasal sextants of right eye and temporal sextants of left eye) was subtracted from the combined thickness of the two right sextants (temporal sextants of right eye and nasal sextants of left eye) to generate a right-left asymmetry score for each eye. For RNFL, right and left quadrants were used rather than sextants. Patients were screened for asymmetry scores ≥ 5 microns in both eyes, where the direction of asymmetry correlated with the side of cortical injury. Data regarding etiology of the visual field defect and its time course were gathered.
Results
In 9 of the 17 patients, both eyes showed GCL thinning contralateral to the homonymous visual field defect and ipsilateral to the side of cortical injury. Of the remaining 8 patients, none demonstrated thinning in both eyes that was ipsilateral to the homonymous field defects. RNFL thinning that was contralateral to the homonymous field defect in both eyes was demonstrated in only 1/17 patients. Excluding patients with tumors of indeterminate onset, the shortest duration between injury and evidence of corresponding GCL thinning was 4 years.
Conclusions
Using SD-OCT, thinning of the GCL, but not RNFL, correlates with post-geniculate visual pathway pathology, thus providing new insights regarding trans-synaptic degeneration of the visual system.
Keywords: 613 neuro-ophthalmology: optic nerve •
531 ganglion cells •
758 visual fields