Can Brighter Lighting Help with Reading Performance?

Can brighter lighting help improve reading performance? That question was asked by researchers presenting “The Effects of Lighting on Reading Speed as a Function of Letter Size” at the 12th International Conference of the International Society for Low Vision Research and Rehabilitation. The authors were William H. Seiple*, Olga Overbury, Bruce Rosenthal**, Tiffany Arango, J. Vernon Odom and Alan R. Morse***.

Increased lighting is often recommended for patients with low vision. The effects of lighting on visual acuity indicate that acuity can be improved by increasing illumination under some conditions. The goal of this study was to quantify under what lighting and text conditions increases in lighting level improved reading performance.

Thirteen normally sighted subjects and nine individuals with vision loss due to dry Age-Related Macular Degeneration participated in this study. The participants read aloud short sentences, printed at sizes ranging from very small to increasingly large (small newsprint to the type size used in children’s primers, i.e. 0.0 to 1.3 logMAR). Some of the normally sighted participants had near-perfect vision, while some of the AMD participants had very low vision, and they read under light levels from very low to very bright. Reading speeds in words per minute were calculated based on the numbers of words read correctly.

For control subjects, those with normal sight, the effects of increasing light levels on reading speed varied with the size of the text and the relative changes in light level. At low levels of light reading speeds were slowest at the smaller letter size, but reached its peak when light was increased to well-lit levels. There was an increase in reading speed, but little change using larger letter sizes. Further increases in light level did not result in significant reading speed gains at any letter size. For AMD patients, similar relative effects of lighting were observed, although the reading data were shifted to larger text sizes and slower reading speeds.

Providing brighter lighting does not always improve reading performance. When recommending lighting intervention, it is important to assess the nature of the visual tasks that a patient wishes to engage in and the typical level of illumination used for those tasks in order to estimate potential gains from increased lighting. In some instances, performance on acuity-limited tasks may be improved by brighter lights; however, the magnitude of this effect, particularly when reading, depends on the relative changes in light level and letter size.

William H. Seiple*, PhD, Vice President of Research, and Director, the Arlene R. Gordon Research Institute, Lighthouse Guild; Olga Overbury, PhD, Ecole d’Optometrie, Université de Montreal; Bruce Rosenthal**, OD, Chief of Low Vision Services, Lighthouse Guild; Tiffany Arango, Northeastern University; J. Vernon Odom, West Virginia University Eye Institute; Alan R. Morse***, JD, PhD, President and CEO,Lighthouse Guild.