Grey filter contact lens as therapeutic option for acquired reduced binocular visual performance

Disturbing binocular problems can be too complex to be treated in such a way that comfortable binocular single vision is restored. The grey filter contact lens could offer a safe and clinically useful way to help these patients. Background: In unilateral acquired reduced visual performance or intractable diplopia the binocular performance often is less than the performance of the better eye, possibly leading to complaints of binocular visual functioning. The hypothesis is to use a grey filter contact lens on the affected eye to obtain more binocular visual comfort. The grey filter changes the binocular central visual image in the brain through delaying the image of the affected eye and has minimal effect on the peripheral vision. The purpose of this study was to evaluate the effect of the grey filter contact lens on the reduction of patients’ binocular complaints in daily life. Methods: In 19 consecutive patients with unilateral acquired reduced visual performance or intractable diplopia a grey filter contact lens was fitted. The contact lens was chosen from six available filters with different transmissions, based on patient preference. The chosen filter contact lens was fitted according to the normal practice of contact lens fitting. Results: The results of 18 patients are reported, one patient was lost to follow-up. Twelve patients (67%) reported good results when wearing the grey filter contact lens. Five patients (28%) discontinued wear of the grey filter contact lens because their binocular visual complaints disappeared during filter contact lens wear and remained absent after contact lens wear was terminated. Conclusion: The grey filter contact lens is a clinically useful, safe, and easily reversible treatment option for patients with binocular visual complaints due to an acquired monocular reduction in visual quality.