Medication bottles can be burdensome, from arthritis-unfriendly child safety locks to the unnecessary waste they create. For many patients, the near-microscopic font size on the label—approximately 10% of lower case letters are as small as 1mm—is just another pill-bottle hassle. But for middle-aged emerging presbyopes, their progressive decline in accommodative amplitude and gain makes reading that tiny text impossible. An Indiana-based research team recently published an investigation in Optometry and Vision Science detailing how small text on product labels impact patients with emerging presbyopia.

The researchers found that, once accommodative amplitude drops to approximately 2.5D, product labels cannot be read at any distance by an uncorrected presbyope. They reviewed the impact of changing viewing distance, accommodation and pupil size on retinal blur size. The team photographed 261 consumer product labels in grocery, personal care and nonprescription (over-the-counter) drug categories and used character recognition software to identify the sizes of the printed letters. They computed the impact of viewing distance on the ratio of blur to letter detail and used published blur ratios of ≤4 and ≤2 to identify the conditions that allowed for letter recognition and proficient reading, respectively. While they found that increasing the viewing distance decreased the blur, increasing distance beyond 35cm for a 1mm text will make the image too small to read proficiently.

Previous studies of texts such as newspapers, books and cell phones show a lower bound of commonly occurring font size of approximately 1.4mm for lowercase letters, consistent with an 8-point font size. This data reveals that even smaller characters are routinely encountered in product labels, especially in over-the-counter and personal care product labels. The authors suggest that optometrists can help by providing presbyopia correction at an early age, but they also advocate for changes in industry. They say the “readability of product labels by people older than 40 years can be improved by increasing font size requirements.”

Xu R, Chelales E, Rickert M, et al. Small text on product labels poses a special challenge for emerging presbyopes. Optom Vis Sci. March 21, 2019. [Epub ahead of print].