Photochromic soft contact lenses contain light-sensitive additives that allow them to darken when exposed to ultraviolet or violet light. One question, however, is whether the lenses influence vision indoors (minimally activated). In this study, we found that the minimally activated lenses improved many aspects of visual function under bright light. Photochromic contact lenses were designed to darken when exposed to outdoor sunlight. The filtering that resulted improved visual function under bright light conditions. Not all bright light exposures occur outdoors. In this study, researchers tested whether a photochromic contact lens improved visual function under conditions where the lens was minimally activated (i.e., no more than it normally would be in an indoor environment). A subject-masked contralateral design was used comparing a photochromic contact lens randomized to one eye against a non-photochromic contact in the other eye of the same subject. Sixty subjects (mean=34.90 ± 11.24 years) were tested. The primary endpoints consisted of four visual function outcomes: photostress recovery, glare disability, glare discomfort and chromatic contrast. Photostress recovery was quantified by measuring the time needed to recover visual acquisition of a grating target after five seconds of an intense xenon white flash exposure; glare disability was evaluated as the energy in a surrounding xenon white annulus necessary to veil a central grating target; and glare discomfort was assessed using bioimaging of the squint response. Chromatic contrast was measured as threshold for a green-yellow (580 nm) grating target superposed on a blue (460 nm) background.

The minimally activated photochromic contact demonstrated improved visual performance compared with the non-photochromic control across all visual functions tested.

Even under conditions of exiguous activation (e.g., as would be expected indoors or while driving at night), researchers wrote that a photochromic contact will improve many of the more deleterious aspects of bright light.

Ulcerative keratitis (UK), or corneal ulcer, is a sight-threatening and US service member readiness-lowering medical condition that begins with a corneal infiltrative event (CIE). Contact lens (CL) wear poses a particular risk for a CIE and, therefore, is restricted for most active duty service members (SMs). In this study, investigators explored a large Department of Defense/Veterans Affairs (DoD/VA) database to estimate the prevalence of UK and CIE, and their association with CL wear. The DoD/VA Defense and Veterans Eye Injury Vision Registry, an initiative of the DoD/VA Vision Center of Excellence, was explored using natural language processing software to search for words and diagnostic codes that might identify cornea injuries and CL wear. The effect of UK and CIE on readiness was explored by evaluating the duration between the first and final visits noted in the database.

A total of 213 UK cases were identified among the 27,402 SMs for whom data were recorded in Defense and Veterans Eye Injury Vision Registry. The odds ratios of UK and CIE being associated with CL wear were 13.34 and 2.20, respectively. A less specific code (superficial corneal injury) was found to be the most commonly used diagnosis in the database, and the odds ratio of CL wearers having that diagnosis was 2.25. CL-wearing patients with corneal disease also required more clinic encounters than those who did not wear CLs.

These findings supported the current restriction on CL wear among non-pilot active duty SMs and quantified the significantly enhanced risk of developing corneal ulcers posed by that habit.

Patients with myopia are at increased risk for the development of glaucoma. The inability to correct for axial length on spectral-domain (SD) OCT translates into lower signal strength and scan reliability in patients with high axial myopia. Researchers evaluated the effectiveness of a contact lens to increase the signal strength and to assess optic nerve dimensions and nerve fiber layer (NFL) thickness using SD-OCT in patients with glaucoma or who are glaucoma suspects with high axial myopia. Patients with axial lengths of more than 25.5mm with a diagnosis of glaucoma or glaucoma suspects were included. The optic nerve cube 200×200 scan using the Cirrus SD-OCT 400 (Carl Zeiss Meditec) was carried out first without the use of a contact lens and then repeated with placement of the contact lens to correct for the spherical equivalent of the refractive error. The primary outcome measure was the change in the average NFL thickness before and after use of the contact lens. Secondary outcome measures included the changes in cup volume, disc area and rim area on OCT.

Twelve patients were recruited (20 eyes); the average axial length was 27.06mm, and the average signal strength interval increased by 1.73. With the use of a contact lens, the average NFL thickness was significantly thicker. None of the changes in the secondary outcome measures were significant: rim area, cup volume or disc area.

Based on the data, researchers reported that the use of a contact lens statistically improved the signal strength and average NFL thickness of the SD-OCT scan. They added that the ability to capture the perimeter of the optic disc accurately could be limited in the setting of peripapillary atrophy, which was present in all but two participants. Researchers suggested that future studies with a larger number of participants and a wider range of axial myopia would be needed to discern if contact lens correction has a greater effect on the highest axial lengths.