Abstract
Purpose :
To characterize rod-, cone- and melanopsin-mediated pupil light responses (PLR) for small focal chromatic light stimuli presented in peripheral and central retinal locations in patients with brain tumors.
Methods :
Eighteen patients with brain tumors and 32 age-similar controls were enrolled. Patients were divided into 2 groups: group I included 10 patients with brain tumors with no apparent contact with the optic apparatus; group II included 8 patients with brain tumors that contacted the optic apparatus. The PLR for small (0.43°) blue and red light stimuli presented at peripheral (21°) and central (4.2°) visual field locations were measured using a chromatic pupilloperimeter under mesopic light adaptation conditions. All subjects underwent a complete ophthalmic exam, standard Humphrey automated perimetry (24-2), color vision test, best-corrected visual acuity, and refraction as well as Spectral-Domain Optical Coherence Tomography (SD-OCT) imaging. All patients underwent brain MRI.
Results :
The SD-OCT thicknesses of macular ganglion cell and inner plexiform layers, as well as peripapillary retinal nerve fiber layer, were within normal limits in all patients. The mean normalized pupil size at 3.7sec following blue light offset recorded in patients from both groups was significantly higher compared with controls in central and peripheral locations (all Ps< 0.003). ROC analysis revealed that this PLR parameter had the largest area under the curve (AUC) in the central retina in group I and in the peripheral retina in group II (90.8%, p=0.003 and 89.3%, p=0.003, respectively). In group II, ROC analysis revealed that the maximal contraction velocity recorded in response to the red light stimulus in the peripheral superior test target had the largest AUC (96.4%, p=0.006).
Conclusions :
Focal intracranial pathologies may be detected by localized melanopsin-mediated sustained PLR for central blue stimulus. Patients with brain tumors involving the visual pathway had an additional defect in the cone-mediated PLR. Quantification of the PLR for focal central and peripheral chromatic stimuli may serve as a novel noninvasive objective diagnostic tool for focal intracranial pathologies.
This is a 2020 ARVO Annual Meeting abstract.