Comparing Rod-Mediated Dark Adaptation in Older Adults before and after Cataract Surgery

Abstract

Purpose

Studies on age-related macular degeneration often use rod-mediated dark adaptation (RMDA) to evaluate macular functional health, studying eyes with cataract and pseudophakic eyes within the same sample. We examine a poorly understood issue—whether rod intercept time (RIT), a measure of RMDA, changes after cataract surgery and intraocular lens (IOL) insertion as compared to RIT before cataract surgery. Cataract may serve as a filter reducing photo-bleach magnitude prior to surgery, biasing RMDA interpretation.

Methods

A pre-/post-cataract surgery design was used. Persons with nuclear sclerotic and/or cortical cataract per the electronic health record were enrolled. Prior to cataract surgery, visual acuity, RMDA, and the LOCS III classification documenting cataract presence/severity were measured. Thirty days after surgery (mean), visual acuity and RMDA were repeated, followed by fundus photos to document macular health.

Results

Twenty-four participants (mean age 72.7 years, standard deviation 5.6) enrolled. All eyes had nuclear sclerotic and nuclear color cataract; 68% had cortical cataract. All IOLs were monofocal with 21 having blue blocking characteristics and 3 had clear IOLs. Most eyes had higher RIT post-surgery (15.6 min, SD 6.7) as compared to pre-surgery (13.7 min, SD 6.4), p = 0.0006, meaning that RMDA was slower post-surgery. Eyes with moderate cataract (<4 on any LOCS III grade) had RIT that increased on average by 0.7 min; those with more advanced cataract (≥4) had RIT that increased by 3.1 min (p = 0.0116). Results were unchanged when clear IOLs were removed from analysis.

Conclusion

RMDA was significantly slower (RIT was greater) following cataract surgery, with the greatest impact on RIT in older eyes after surgery for more advanced cataract. These findings suggest that persons with more advanced cataract may bias results when evaluating RMDA using RIT.

Keywords:

• Rod-mediated dark adaptation
• cataract
• cataract surgery

Disclosure Statement

No potential conflict of interest was reported by the authors. Cynthia Owsley is an inventor on the device used to measure dark adaptation in this study. She is a consultant for Regeneron and Johnson & Johnson Vision, all outside this work. There are no commercial relationships for other authors.

Data Availability Statement

Data from this study are available by contacting the corresponding author.

Additional information

Funding

National Institutes of Health (NHLBI T35HL007473) as part of the Summer-Term Health-Related Training in Professional Schools program at UAB’s Heersink School of Medicine, NIH grants (R01EY029595 and P30EY03039), Dorsett Davis Discovery Fund, EyeSight Foundation of Alabama, Alfreda J. Schueler Trust, and Research to Prevent Blindness.