Impact of Light-Filtering Lenses on Visual Photosensitivity Threshold Reliability in Individuals with Traumatic Brain Injury

Abstract

Purpose : The Ocular Photosensitivity Analyzer (OPA) quantifies a person’s visual photosensitivity threshold (VPT) using an automated testing protocol. The purpose of this study is to examine the impact of light-filtering lenses on the VPT reliability using the OPA in individuals with Traumatic Brain Injury (TBI).

Methods : The OPA measures VPT by presenting light stimuli of varying intensity in unequal ascending/descending steps. Participants indicate discomfort and after 10 response-reversals, a VPT is calculated. Catch trials are random, repeated stimuli interspersed at regular intervals to generate an inconsistency index based on the subject’s responses; a positive inconsistency signifies a response shift from discomfort (positive) to no discomfort (negative), while a negative inconsistency is the reverse. In 2 study visits, 46 TBI and 46 healthy participants underwent 5 OPA tests: no lens (NL), plano (PL), blue-light (BL), FL-41 (FL), and gray (GL) light-filtering lenses (Figure 1). The reliability of the VPT measurements across visits was assessed using Intraclass Correlation Coefficient (ICC) for each lens condition. A repeated measures ANOVA analyzed catch trial agreement, exploring within-light filtering conditions and between-group differences.

Results : TBI group had a lower VPT than the healthy group in all conditions. In both groups, the VPT was higher (higher light tolerance) when using the FL and GL lenses, compared with all other lenses (p<0.05) (Figure 1). VPT ICCs were good for all conditions across both groups (Table 1a). Finally, overall catch trial accuracy for TBI subjects in the NL was 74.4±14.5%. Likewise, for healthy subjects, overall catch trial accuracy was 80.1±15.1%. There was no significant difference in overall catch trial accuracy between groups (p = 0.295), or among the 5 light-filtering conditions (p = 0.091) (Table 1b). Subject response consistency remained stable as shown by no statistically significant variations in catch trial accuracy across groups and conditions.

Conclusions : Individuals with TBI demonstrated significantly lower VPT compared to healthy subjects. Both FL and GL lenses effectively increased light tolerance in both groups. With its high test-retest reliability and catch trial accuracy, the OPA VPT proves to be a reliable and repeatable tool for measuring light tolerance and monitoring treatment effects in the TBI population.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.