The effect on blink frequency of a selective blue-filtering photochromic lens in patients with benign essential blepharospasm.

Objective: The aim of this clinical study was to assess the impact of a non-invasive selective blue-filtering photochromic lens coating Crizal Prevencia on the treatment and response of benign essential blepharospasm (BEB). Patients and methods: Twenty-four patients were recruited in the outpatient clinic of the Medical University of Vienna in a randomized, double-blind, cross-over study design. Blink frequencies were assessed in patients with BEB before and 14 days after intervention with either a filtering ophthalmic lens or a placebo lens, respectively. Outcome parameters include sub-group analysis of a blink frequency under six different conditions: three photopic conditions, one resting condition, one reading condition, and one video game condition. Results: From 24 recruited patients, 15 patients were available for final analysis. Comparing the optical blue filtering lens to placebo, showed a reduced blink frequency in specific subtests, but not compared to baseline. Discussion: In conclusion, optical filtering glasses might have a beneficial effect on BEB and provide a non-invasive therapeutic add-on option, in addition to botulinum neurotoxin therapy, for patients with BEB and should necessarily be further investigated in a multicenter setting, resulting in larger sample sizes to gain valid information about the effect of photochromic blue filter glasses in BEB.