Clinical risk factors for age-related macular degeneration: A case-control study.

Sir,

Age-related macular degeneration (AMD) is the leading cause of legal blindness in the western world mainly occurring in people aged >55.[1] Recent success in treatment of patients with neovascular AMD raises the value of identifying patients at higher risk at earlier stages.[2] Therefore, we investigated the risk factors associated with AMD in an Iranian population.

In a prospective case–control study, we evaluated 228 patients with AMD and 220 individuals as the control group in the Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran. Our Institutional Review Board approved the study protocol, and all participants signed an informed consent. The diagnosis of AMD was made based on stereoscopic color retinal photographs which were taken with a standard 30° fundus camera (Zeiss FF4 series, Zeiss, Jena, Germany) centered on the optic disk. Patients were enrolled if they had bilateral large drusen or unilateral late AMD in one eye and large drusen in the other eye. In the control group, the absence of AMD and any other retinal diseases were confirmed by dilated ophthalmoscopy and fundus examination.

The mean age was 69 ± 5 and 70 ± 4 years in the AMD and control group, respectively. Males were 59.2% and 53.6% in the AMD and control group, respectively. Furthermore, unilateral involvement and bilateral AMD were observed in 88 patients (39%) and 139 patients (61%), respectively. Of those evaluated risk factors, the presence of hypertension (defined as systolic blood pressure >160 mmHg, diastolic blood pressure >95 mmHg), smoking, sun exposure, and lens opacity were significantly more frequent among AMD patients compared to the healthy controls (P < 0.001). However, gender, diabetes mellitus (DM), hyperopia, light color iris (blue, gray, or green), alcohol consumption, and intraocular pressure >21 mmHg were not significantly different between both groups (P > 0.05).

We found that almost 50% of our AMD patients were misdiagnosed prior to our clinic visit. Even in the case of precise diagnosis, our patients had some delay until their first refer to our center. This shows that in our population, neither AMD is treated efficiently nor it is under prevention. Therefore, well awareness of its risk factors may enable us for better establishment of prevention strategies.

The associations of hypertension, DM, and sunlight with AMD have been controversial in the literature, and there are studies supporting and opposing the role of hypertension and DM in the development of AMD.[34] These controversies may arise from genetic, lifestyle, and environmental factors which significantly vary between different studies’ populations. Sunlight and also cigarette ingredients can play an oxidative role in the retina and photoreceptors resulting in AMD development.[5]

In conclusion, our study revealed that age, cigarette smoking, hypertension, high and long exposure to sunlight, and having an outdoor job are risk factors for AMD. Of these, hypertension and cigarette smoking are modifiable risk factors which their control may have sensible benefits. On this basis, preventive strategies specific to our population can be established.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.