Determination of Visual Impairment Associated with Alcohol Consumption

Sir,

We read with great interest the recently published article “Alcohol consumption and visual impairment in a rural northern Chinese population” by Li and co-authors.1 In this study, researchers investigated alcohol drinking status and the association between drinking patterns and visual impairment in an adult population in Northern China. In conclusion, it was reported that high levels of alcohol consumption are deleterious to eye health. However, there are some points that we would like to address about this study.

First, the authors stated that heavy alcohol intake was significantly associated with an increased risk of corneal diseases when compared with abstainers. In the literature, there have been many studies evaluating the relationship between drinking patterns and various corneal diseases. For instance, Thomas and colleagues found a significant relationship between alcohol consumption and arcus senilis.2 Also, Kim and co-workers reported that alcohol consumption induced tear hyperosmolarity and shortened tear break up time and triggered the development of ocular surface diseases.3 Similarly, Cumurcu and colleagues showed that men who drank heavily had decreased tear production, tear film instability, and significant degeneration of the ocular surface epithelium when compared with normal subjects.4 Therefore, when detailing these types of corneal diseases it would have been better if the authors had specified this association. In addition, there is no uniformity between questionnaires categorizing drinking frequencies and quantities in these studies. Accordingly, this variation makes it difficult to assert the use of alcohol alone in the etiology of visual impairment. On the other hand, as is known, inflammation, metabolic disorders, tumors and hereditary optic neuropathies may all also lead to visual impairment. However, neither the state of inflammation nor the presence of metabolic diseases were evaluated in the current study. For this reason, at least, assessing the blood levels of simple inflammation markers like erythrocyte sedimentation rate and/or C-reactive protein to a diagnosis of systemic inflammation, fasting plasma glucose levels to diagnose diabetes and blood pressure readings to diagnose hypertension would have been useful to aid the understanding of the etiopathogenesis of visual impairment in the current study population.

Second, the authors mentioned the basic ophthalmic examination included an examination of the fundus by direct ophthalmoscopy in the materials and methods section of the original study. But they didn’t mention anything about retinal findings of alcohol consumption in the results or discussion. It should have been detailed whether or not there exists a relationship between alcohol consumption and retinal diseases. For instance, Beulens and co-workers showed a U-shaped relationship between alcohol consumption and risk of proliferative retinopathy.5 Also, moderate alcohol consumers had a decreased risk of proliferative diabetic retinopathy compared with abstainers and heavier drinkers. According to Fan and co-authors, heavy drinking was associated with higher odds of age-related eye diseases such as cataract, glaucoma, age-related macular degeneration, and diabetic retinopathy.6

In conclusion, detailing the type of corneal diseases evaluated in the current study, excluding the other common causes of visual impairment and detailing retinal findings of alcohol consumption would have provided more reliable results and improved the credibility of the whole article.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

This paper received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.