Can Sleep Apnoea be a Risk Factor for Glaucoma?

No one wants to be blind. This is why we have to keep our eyesight healthy and be free from illnesses that may cause blindness. One such illness is glaucoma. Glaucoma is seen as a disturbance of the nerves of the eye and can lead to eye tissue damage and to visual field disturbances or blindness. The mechanism behind glaucoma is not yet fully established although some risk factors have been implicated. Such risk factors include diabetes mellitus, hypertension and migraines.

Recently, sleep apnoea has been added to the list of risk factors for glaucoma. This is because there are certain individuals with sleep apnoea who were reported to be at a greater risk of developing Primary Open Angle Glaucoma (POAG) and its normotensive variant (NTG). Recently, a study was conducted by Khandgave et al to ascertain the significance of sleep apnoea as a risk factor in patients with glaucoma. The findings were published in the July 2013 issue of the Journal of Clinical and Diagnostic Research.

The conducted study was a non–randomized, crosssectional study undertaken at an urban teaching hospital. A sleep disturbance questionnaire and the Epworth sleepiness scale were used to screen the potential cases of sleep apnoea amongst 40 glaucomatous subjects, with both Primary Open Angle Glaucoma (POAG) and Normotensive Glaucoma (NTG), as well as 40 controls. Those which gave a positive response to the questionnaire were subjected to poly-somnography for the diagnosis of sleep apnoea, with the calculation of the Apnoea Hypopnoea Index. The data was analysed by using the Chi–square test and the odds ratio calculations.

The results revealed that there were positive responses to the sleep apnoea questionnaire from a total of twenty participants, 16 (40%) from the glaucoma group and four (10%) were obtained from the control group. In the glaucoma group, ten (37.03%) of the 27 POAG individuals, and six (46.15%) of the 13 NTG cases showed significant positive responses to the questionnaire. Four subjects (10%) (1POAG, 3 NTG) from the glaucoma group and one (2.5%) from the control group were diagnosed to have sleep apnoea by polysomnography. The percentage of the sleep apnoea positive cases was higher among the NTG subjects (23.07%) than among the POAG subjects (3.7%). This study had an odds ratio of 4.333 (>1) and a p value of 0.382.

Given these results, the authors concluded that the association between sleep apnoea and glaucoma were not statistically significant. However, the authors also commented that the comparisons were difficult. Some studies were conducted only on the POAG patients, while others assessed only the NTG patients. Furthermore, the diagnostic tests for sleep apnoea were not uniform. The authors claimed that some of the limitations of the study were the following: its small sample size, the short duration of the study and the presence of confounding factors like diabetes mellitus and systemic hypertension. More research is needed as to whether sleep apnoea can be considered a risk factor for glaucoma.

Reference:  

Khandgave TP, Puthran N, Ingole AB, Nicholson AD. The assessment of sleep apnoea as a risk factor in glaucoma. J Clin Diagn Res. 2013 Jul;7(7):1391-3. http://www.ncbi.nlm.nih.gov/pubmed/23998072

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