Smaller spot sizes show bitemporal visual field defects missed by standard Humphrey perimetry.

Purpose: To compare the sensitivity of Humphrey visual field (HVF) tests using different stimulus spot sizes for the detection of early visual field defects in a patient with known chiasmal compression. Observations: A 21-year-old man with a suprasellar tumor compressing the optic chiasm had multiple normal 24-2 HVF tests using a stimulus size III test spot over 5 years. Subsequent ganglion cell complex (GCC) analysis on optical coherence tomography (OCT) showed ganglion cell layer + inner plexiform layer (GCL + IPL) thinning in the macula. Therefore, HVF testing was performed using smaller test spots. Size I and II spots both revealed a superior temporal field defect in each eye that was missed by the standard size III spot. Conclusions and importance: These findings demonstrate that HVF testing using stimulus size I or II spots can reveal a visual field defect that was missed when using a standard size III spot. We therefore recommend routinely performing HVF testing in patients with known chiasmal compression with a stimulus size I or II spot, when testing with a stimulus size III spot is negative.