Macular ganglion cell complex measurement in bilateral retrobulbar optic neuropathy without a relative afferent pupillary defect.

Purpose: This study aimed to demonstrate the clinical usefulness of measuring the macular ganglion cell complex (GCC) for the early detection of axonal loss in eyes with bilateral retrobulbar optic neuropathies.

Patients And Methods: We retrospectively reviewed the medical records of three patients with bilateral toxic, ischemic, or infiltrative retrobulbar optic neuropathy.

Results: No relative afferent pupillary defect was detected in any patients. The results of the fundus examinations were unremarkable at the initial presentation except for slight optic disk pallor in the right eye of Case 3. Magnetic resonance imaging showed no abnormal findings in Cases 1 and 2. Measurement of the macular GCC clarified the presence of axonal loss in all three cases with diagnostic uncertainty. Although reduction in the macular GCC thickness was not observed initially in Case 2, it became evident later when both optic disks still appeared normal.

Conclusion: A reduction in the macular GCC thickness seemed to precede the appearance of optic disk pallor and occurs regardless of toxic, ischemic, or infiltrative retrobulbar optic neuropathy. The current case series suggested that measurement of the macular GCC facilitated early differentiation between bilateral retrobulbar optic neuropathy and nonorganic visual loss, which can otherwise be challenging in some cases.