To the Editor:

The epidemiology of rhegmatogenous retinal detachment (RRD) has been analysed in central and northern Europe, with incidence rates ranging from 7/100,000 to 22/100,000 inhabitants [1,2,3,4]. The knowledge of the incidence distribution of RRD would further our understanding of how climate and other factors behave and interplay in different populations and help to promote awareness [5] about this potentially blinding disorder. In a previous report we analysed the association between RRD and solar radiation [4]. In this study we investigate the incidence of RRD and its clinical characteristics in a Spanish general population.

We retrospectively analysed all the retinal detachment (RD) patients diagnosed between 2008 and 2014 in the Complexo Hospitalario Universitario de Pontevedra, which was the only centre with a capacity for vitreoretinal surgery in Pontevedra at the time. RRD was defined as an accumulation of subretinal fluid of at least 2-disc diameters in size associated with one or more full-thickness retinal breaks. Non-RRD cases were also investigated. Only those patients residing in the area at the time of diagnosis were included in the study. The incidence and epidemiological characteristics were analysed using the R language for statistical computing 2017 statistical package. The study conformed to the principles of the Helsinki Declaration and was reviewed and approved by the Regional Research and Ethics Committee.

A total of 259 patients from a population of 302,688 were diagnosed with RRD. The average annual incidence was 12.6/100,000 people (95% CI 9.2–17.3). This incidence increased with age, showed seasonal variation and was higher in men. The incidence of non-RRD was 5.0/100,000 people (95% CI 3.0–8.3). This incidence was also higher in men but did not increase with age or show seasonal variation (Table 1). The clinical characteristics of incident RRD and non-RRD cases are presented in Table 2.

Table 1 Incidence of rhegmatogenous and non-rhegmatogenous retinal detachment by age and sex.
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Table 2 Clinical characteristics of incident retinal detachment cases.
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To our knowledge, this is the first study to examine the incidence of RD in a general population in Spain. The main finding was that the incidence of RRD was 12.6/100,000 inhabitants and that it was associated with the male sex and ageing [1,2,3]. RRD incidence shows great geographical variability probably due in part to differences in disease definition between studies [5] (Table 3). The effect of solar radiation on the seasonal pattern of RRD incidence reported previously [4] could contribute to the relatively high incidence rates observed in this study. The increase in RRD incidence over the years observed by several authors [2] explained among other factors by climate change also supports this hypothesis.

Table 3 Incidence of rhegmatogenous retinal detachment in population-based studies.
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Several studies confirm that approximately two-thirds of the population are right eye dominant, which could explain why the right eye was more frequently affected than the left one as there is a tendency to close the nondominant eye in strong sunlight [4]. The degree of inbreeding of this population due in part to the historical isolation of this geographical area [4] might not only explain the higher bilaterality rate observed in this study compared to others [3] but also other epidemiological characteristics of this disorder. Further research is needed to better characterize the epidemiology of RRD in this region and globally.