Visual acuity testing under low luminance conditions emerged as an optimal quantitative measure of retinal function in early AMD.

Asthenopia symptoms were investigated in visually-normal subjects without computer-related vision symptoms after prolonged reading from: smartphone versus hardcopy under photopic conditions, and smartphone in conditions of ambient versus dark room illumination. After reading from the smartphone, total symptom scores and nine out of ten questionnaire symptoms were significantly worse than for the hardcopy ("blurred vision while viewing the text, "blurred distance vision after the task", "difficulty in refocusing from one distance to another", "irritated or burning eyes", "dry eyes", "eyestrain", "tired eyes", "sensitivity to bright lights" and "eye discomfort"). Mean total symptom scores and scores for "irritated or burning eyes" and "dry eyes" were significantly higher for the dark versus photopic conditions. In conclusion, prolonged smartphone reading could cause worse asthenopic symptoms than reading from a hardcopy under similar conditions. Symptoms could be even worse when reading from a smartphone in the dark.

Halo size increases with age following a power model. The normal halo size values provided could help clinicians distinguish between normal or abnormal glare problems. The intersession repeatability observed for halo size measurement indicates this method could be useful for assessing visual impairment caused by glare.

The mesopic contrast sensitivity and glare sensitivity seem to be stable until the age of 50 years, from which point they start to decline at a rate of 0.1 log contrast sensitivity loss per decade. Drivers with poor visual acuity and/or older drivers who avoided night driving presented worse mesopic contrast sensitivity and greater glare sensitivity.

This study provides data on the accommodative capacity of a population of children with reading difficulties. Our findings suggest a reduced monocular accommodative amplitude and binocular accommodative facility, such that this function should be assessed by an optometric clinician in children whose reading level is below average.