Photophobia in patients with traumatic brain injury: Uses of light-filtering lenses to enhance contrast sensitivity and reading rate

Abstract

Patients who have sustained traumatic brain injury (TBI) often experience a new, intense and chronic photophobia. Photophobia, an intolerance to light, is an incompletely understood, subjective symptom, which has been divided into ocular and central types. Various commercial sources of light-filtering lenses have been developed, which have proven to be successful in diminishing visual symptoms expressed by patients who are photophobic. However, despite the many subjective reports of improved visual performance and comfort with use of these filters, there has been little documentation of actual enhanced visual sensitivity/efficiency. Letter contrast sensitivity (CS) and reading rate were measured in patients with TBI, who, despite good ocular health, experienced significant light intolerance. These patients exhibited up to two fold increases (0.3 log units) in binocular letter contrast sensitivity, as measured with the Pelli-Robson Letter CS Chart, in the presence of selected Corning Photochromic Filters (CPF), as compared to performance in the absence of CPF filters, or to that of similarly treated normal observers. These same patients demonstrated reading rates enhanced up to 39% above that measured in the presence of nearpoint optical correction alone. Reading performance of normal observers was unaffected by similar light filtration. These data provide objective evidence for improvement of visual function provided by light-filtering lenses in patients who become photophobic after TBI. Contrast sensitivity testing and assessment of reading rate add objective criteria for the clinical selection of light-filtering lenses in the treatment of TBI-induced photophobia.