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How eyes see in dim light: studying rod and cone function

Plain-English translation of NCT02617966 on ClinicalTrials.gov ↗ · Source last updated July 2026 · Translation generated July 2026 · How we translate trials

What is this trial?

This research study investigates how the light-sensing cells in your retina (called rods and cones) work in people with and without retinal diseases. Researchers will use specialized equipment to measure your vision in different lighting conditions and track how your eyes adjust from darkness to light. The goal is to build a better understanding of how retinal diseases affect vision, which could help improve diagnosis and treatment in the future.

Many people with retinal diseases like retinitis pigmentosa and Stargardt's disease have trouble seeing in dim light, but doctors don't have clear, standardized ways to measure these specific vision problems. This study will establish what normal vision looks like under different lighting conditions, making it possible to better detect and track vision loss in patients with retinal disease.

Do you qualify?

You likely qualify if…

you are five years old or older
you can understand and sign the informed consent form (or have a legal guardian who can)
you are able to cooperate with vision testing
you have been diagnosed with a retinal disease with evidence of vision loss or degeneration (if enrolling in the affected group)
you have measurable vision in at least one eye (if enrolling in the affected group)
you have vision of 20/20 or better with or without glasses (if enrolling as a healthy volunteer)

You likely don't qualify if…

you have cataracts, corneal scarring, or other eye problems that block the doctor's view of your retina
you have significant vision loss that prevents you from cooperating with testing
you are unable to understand or consent to the study

What participation looks like

You will visit the National Eye Institute for vision testing sessions. Researchers will use specialized equipment (like perimeters and computer monitors designed for vision testing) to measure how well your eyes see in dim and bright light, and how quickly your eyes adjust when moving between different lighting levels. Some participants may also complete questionnaires about their vision in low-light situations. The study is observational, meaning you won't receive any medication or undergo any surgery—just specialized vision tests.

AI-generated summary from trial data · Jul 13, 2026 · Not medical advice

How eyes see in dim light: studying rod and cone function

What is this trial?

Do you qualify?

What participation looks like

Trial locations