Photophobia or intolerance to light is a handicapping symptom associated with a variety of ocular, cerebral and systemic disorders. Despite being studied for many years, its pathophysiological mechanisms are still partly understood. Most of the research focuses on its association with diseases such as migraine where the important role played by retinal photosensitive cells called ipRGCs has been highlighted. Photophobia is often resolved following the treatment of the underlying associated disease. There are, however, cases where no cure exists and photophobia remains. Regardless of its origin, use of colored filters blocking specific light wavelengths is used for photophobia relief. Studies have shown a subjective relief of patients’ photophobia by using filters. Some studies have linked specific filter colors to specific diseases associated with photophobia. Recent findings suggest that the relief provided is linked to the light wavelength blocked by the filters. There are currently no scientifically based guidelines concerning the filter selection process. This led to the examination of filter choices of patients with posterior segment pathology at the Jules Gonin Low Vision Service to better understand how disease pathophysiology might influence patients’ filter choice and compare with results from the medical literature.
Filter choices of adult patients evaluated in the Low Vision Service at the Jules Gonin Eye Hospital between July 2019 and November 2022 were retrospectively reviewed as part of an internal quality control. From the information available, 41 pairs of filters selected by patients for whom a posterior segment pathology was mentioned in relation to photophobia were identified. These filter choices were then descriptively analyzed for variables such as visual acuity, color of filters chosen, and disease associated.
The mean age of patients was 65.6 years (range 20 to 91 years). Visual acuity (VA) in the better eye was >0.5 or better in 19 patients (46%) while 22 (54%) of them had a VA of 0.49 to counting fingers. Nearly half of the patients (20 patients) had one posterior segment pathology whereas 21 patients had an accumulation of diseases. The most common posterior segment pathology was age-related macular degeneration (ARMD). Others included retinal dystrophy, diabetic retinopathy, central serous chorioretinopathy, ischemic optic neuropathy, retinal artery occlusion and glaucoma. The most popular choice of filter color was grey. Patients suffering solely from ARMD chose pink and brown filters when having a better VA and grey filters when having a worse VA. For these patients VA could be an added filter selection criteria on top of wavelength. Pink, yellow, orange or a mix of filters were also chosen by patients with other posterior segment lesions. All the filters selected by ARMD patients blocked light wavelengths activating rods and ipRGCs suggesting a possible role of these cells in ARMD associated photophobia.
Despite the number of patients being too small to draw any conclusion, these results pave the way for prospective studies with well-characterized ocular pathologies, objective ocular, and medical data as well as an increased number of patients that will be helpful for understanding and optimizing filter choice for photophobia as well as better understanding of its mechanisms.