Sleep apnoea in the eye clinic

Anju Kadyan, Specialist Registrar, Ophthalmology,

Other Contributors:

January 18, 2008

Dear Editor,

We agree with the authors’ recommendation on the need for a sleep history in the eye clinic and probably having a lower threshold for referral to sleep physicians for further sleep studies.[1] However, we would like to bring to their attention other epidemiological studies where screening tools/sleep history have shown a high prevalence of sleep disorders in patients with ocular disorders other than non- arteritic anterior ischaemic optic neuropathy (NAION). These include primary open angle glaucoma (POAG), normal tension glaucoma (NTG), floppy eye lid syndrome (FES) and more recently central serous chorio-retinopathy (CSCR).[2-5] The evidence from these studies is summarized in table 1.

The literature shows a higher prevalence of sleep disorder than that reported in the general population in the United Kingdom by Ohayon et al (1.9% of population sample, n=4972) based on the minimal criteria of the International Classification of Sleep Disorders.[6]

We note the authors have adjusted the statistical analysis for glaucoma among other factors, but the proportion of patients diagnosed with glaucoma in the study and control groups is not mentioned. They also do not mention the ocular diagnosis of the randomly selected control group from the ophthalmology clinics and if any exclusion criteria, other than NAION was used. This may be the reason for their study having a lower proportion of patients with symptoms consistent with SAS than previously reported. The other reason can be the different screening methods used in these studies.

Also, the authors do not mention if the patients scoring positive on the Sleep Apnoea scale of the Sleep Disorders Questionnaire (SA-SDQ) were referred for sleep studies. Offering polysomnography or even limited sleep study to the study sample and comparing the outcomes with the SA-SDQ scores could provide the required evidence or validation, as mentioned by the authors, on the need for lower cut-off points for this patient sub-group.

We recently conducted a similar study in the general eye clinic population, which is under consideration for publication at the present time. Following a review of the various components of the screening questionnaire; patients with glaucoma were more likely to report episodes of apnoea, morning headaches, short term memory loss and poor concentration. We therefore suggest the authors also do a further analysis of the responses obtained to the 8 questions addressing the specific symptoms of SAS in the SA-SDQ, as they might be able to provide an additional weighted score for screening in their patient subgroup.

References

1. Li J, McGwin G, Vaphiades MS, Owsley C. Non-arteritic anterior ischaemic optic neuropathy and presumed sleep apnoea syndrome screened by the Sleep Apnoea scale of the Sleep disorders Questionnaire (SA-SDQ). Br J Ophthalmol 2007; 91:1524-1527.

2. Hakki Onen S, Mouriaux F, Berramdane L, Dascotte JC, Kulik JF, Rouland JF. High prevalence of sleep disordered breathing in patients with primary open angle glaucoma. Acta Ophthalmol Scand 2000; 78: 638-641.

3. Marcus DM, Costarides AP, Gokhale P, Papastergiou G, Miller JJ, Johnson MH, Choudhary BA. Sleep Disorders: A risk factor for normal tension glaucoma. J Glaucoma 2001; 10: 177-183.

4. McNab AA, The eye and sleep. Clinical Experimental Ophthalmology 2005; 33: 117-25.

5. Leveque TK, Yu L, Musch DC, Chervin RD, Zacks DN. Central serous chorioretinopathy and risk for obstructive sleep apnoea. Sleep Breath 2007; 11: 253-257.

6. Ohayon MM, Guilleminault C, Priest RG, Caulet M (1997) Snoring and breathing pauses during sleep: telephone interview survey of a United Kingdom population sample. BMJ, 314, 860–863.

Conflict of Interest

None declared