Saccadic Latencies Extended Following COVID-19 Infection

Saccadic latencies are extended and saccadic errors are more common in patients who have recovered from a COVID-19 infection, according to data presented at the Association for Research and Vision in Ophthalmology (ARVO) Annual Meeting in New Orleans, April 23–27, 2023. Slower fixation change may further establish impacts of COVID-19 beyond the respiratory system.

Investigators monitored saccadic latencies by employing an eye-tracking device that measured eye movements during the working-memory-driven saccadic task which cued a location change in the opposing direction after delay periods of various lengths; 0.5, 1, or 2 seconds. Researchers included saccadic latency data of 6 adults (mean age, 19.67±1.03 years) who had experienced COVID-19 infection an average of 8.16 months prior, and 6 healthy individuals who were placed into a control group (mean age, 18.5±1.4 years).

In a mixed-effect analysis of variance (ANOVA) model, little interaction effect in saccadic latency occurred. However, significant differences emerged for the main effect of delay (P =.028), and between groups (P =.01). As delay lengthened, both groups reacted faster, but the case group generally took longer to make a direction shift — approximately 50 to 100 milliseconds compared with control individuals, and the effect was most pronounced at briefer delay intervals.

Regarding errors, there were no significant differences based on interaction effect or main effect of delay, although the main effect of group demonstrated a larger variation (F (1, 27) =6.15, P =.02). “Participants with post-COVID infection made more incorrect saccades during and after delay period than controls,” according to researchers.  “COVID-19 can lead to slower processing speeds and poor inhibition, as indicated by longer saccadic latencies and more saccadic errors.”

Reduced cognitive function — changes in attention, processing speed, and memory have been previously reported, suggesting possible after-effects of COVID-19, but magnitude and duration of saccadic latencies are still unknown.

A limitation of this study is its exploratory nature.