Dear Editor,

We want to thank Mahendra Singh, Suraj Kumar Chaurasiya, Ashish Chander, and Radhika Radhika for their interest in our manuscript “Photosensitivity and filter efficacy in albinism1”. The readers raise some issues that we would like to address below.

First, they would prefer a longitudinal study. Our study was a cross-sectional study and did not address temporal changes in photosensitivity or filter preference. Albinism is a life-long condition and all participants had at some point previously been seen at our clinic, thus none of the participants were naïve to optical rehabilitation. Photosensitivity or filter preferences may change with time either because an eye condition may change, e.g. onset of cataract, or because life demands, e.g. a new job, may require it. Of course, this could be relevant to follow over an extended period of many years but such a study may prove difficult to conduct as research methodology, e.g. improved questionnaires addressing photosensitivity, may be developed or new filters may be available. Also, asking the same person to relate to their photosensitivity repeatedly may change how that person perceives photosensitivity.

Second, the readers would have preferred objective measures of photosensitivity. Whereas such measures may be interesting from a scientific point-of-view, we were mainly interested in the participants experiences from their everyday life and how photosensitivity influenced their visual function. It was also the subjective experience of photosensitivity that we aimed to address with the filters. The main learning from our study was that an individual approach is required when providing optical rehabilitation to patients with albinism.

The sample size is questioned. The birth prevalence of albinism in Denmark is 1/14,0002 and with a population of 5.9 mio (https://www.dst.dk/da/Statistik/emner/borgere/befolkning/befolkningstal) our study sample accounts for roughly 20 % of patients living with albinism in Denmark. Although the sample size may be small in terms of the global number of patients with albinism, we believe it is representative of Denmark. The diversity of the study is also questioned. We did include patients of non-Danish ancestry but of course a study conducted in a North-European country may not be directly representative of patients with albinism living in other parts of the world, not least because life conditions, e.g. the amount of sunlight, may be quite different. Nevertheless, we believe that the main learning from the study – that optical rehabilitation should be tailored to the individual patient - can be generalized to other populations.

Finally, the readers request detailed information on filter characteristics. This information including transmission curves of the filters is available in the Supplementary material.

We welcome studies from other countries as there is a lack of evidence on how to provide the best optical rehabilitation for patients with eye diseases.

Tanja B. Hansen, Joaquim Torner-Jordana, Line Kessel