Drivers’ Brake Reaction Times Improve After Bilateral Cataract Surgery

The study also shows the importance of contrast sensitivity in driving.

Bilateral cataract surgery significantly improves drivers’ neurological brake reaction times (BRTs) and related stopping distances, according to results of a study published in Acta Ophthalmologica. The researchers believe the findings indicate the importance of presurgical contrast sensitivity (CS) evaluation, especially for patients who drive regularly.

The investigators looked at 64 Austrian patients who were assessed on the day of cataract surgery, and 4 weeks post-surgery. The control group included 43 healthy participants. The researchers used a driving simulator to analyze break reaction times following a visual stimulus. 

All time measures improved after cataract surgery including brake reaction time (BRT), neurologic reaction time (NRT), foot transfer time (FTT) and brake pedal travel time (BPTT). 

The study also shows stopping distance enhanced significantly following surgery (22.3 meters vs 19.9 meters at 50 km per hour). Best-corrected visual acuity (P <.001) and CS (P <.001)  improved significantly following surgery.

The CS before cataract surgery was negatively associated with neurologic reaction time (NRT). Women in the study demonstrated no variation in NRT vs men both before and after surgery. Compared with men, however, women demonstrated significantly decreased FTT and overall BRT following cataract surgery. The control group exhibited better CS vs patients before surgery but worse vs those after surgery.

Greatest improvements in brake measures were noted in NRT, which represents the initial response to the visual stimulus. Previous literature shows CS significantly correlated with driving performance.

Consequently, the investigators related CS and visual acuity with NRT and discovered a negative association between NRT and CS. This result implies that the slower the NRT, the weaker the CS.

In addition to bolstering the importance of CS evaluation during screening for cataract surgery, the investigators report that “these findings could even help improve driving safety in the future when they are incorporated into the physical examinations and ocular assessments conducted before issuing a driving license.”

A limitation of the study is that patients and volunteers displayed a vigilant, “ready-to-break fashion” in anticipation of the visual stimulus, therefore findings may not be generalizable to real-world conditions.


Nowosielski Y, Leitner B, Rauchegger T, et al. Bilateral cataract surgery improves neurologic brake reaction time and stopping distance in elderly drivers. Acta Ophthalmol. Published online June 2, 2021. doi:10.1111/aos.14748