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Natasha V Nayak, Tenley Bower, Leela Raju, Amy C Nau, Alex Mammen, Roheena Kamyar, Deepinder Dhaliwal; Sleep Position and Obstructive Sleep Apnea in Keratoconus. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1584. doi: https://doi.org/.
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Keratoconus (KCN) has been associated with atopy, eye rubbing, and a variety of systemic conditions including obstructive sleep apnea (OSA). There has been anecdotal suggestion that asymmetric keratoconus may be partly explained by sleeping on the ipsilateral side. Our purpose was to investigate the role of sleep position and OSA in patients with KCN.
Telephone survey and retrospective chart review of patients with KCN. Patients were screened for OSA (validated Berlin Questionnaire) and surveyed regarding sleep position, contact lens wear, eye rubbing, and eye trauma. Patient charts were reviewed for past ocular history, manifest refraction, slit lamp exam findings, and Scheimpflug imaging measurements (Oculus Pentacam), including flat keratometry (K), maximum keratometry (Kmax), posterior elevation at thinnest point (PETP), central corneal thickness (CCT), and pachymetry at thinnest point (TP). Inter-ocular differences (IOD) were defined as right (R) minus left (L) eye measurement (IOD would be negative if L>R). Non-parametric (Wilcoxon rank-sums) and chi-squared tests were used in analysis.
Twenty-one patients with KCN (33.4 ± 11.1 years old; 76% male) were recruited. The sleep survey found 12 (57%; 5 right, 6 left, 1 both) side sleepers, 5 (24%) prone, and 4 (19%) supine. 19 (90%) admitted to rubbing their eyes and 14 (66%) had atopic disease. Five (24%) screened positive for OSA, although none had prior diagnoses or sleep studies. Side-sleepers had a higher magnitude of (absolute) IOD in spherical equivalent of refraction (p=0.04). Patients who slept R-face down had significantly higher IOD in flat K, and lower IOD in TP/CCT compared to L-face down and neutral face position sleepers (p<0.05). This is consistent with the finding that R-face down sleepers were more likely to have higher flat K and thinner corneas (lower TP/CCT) in the ipsilateral eye (chi-squared, p < 0.05). 8 (38%) patients were aware they placed pressure on their eye(s) while sleeping. Patients who believed they placed pressure on their R eye while sleeping had significantly larger IOD in Kmax and PETP compared to patients who denied placing pressure on either eye (p=0.04).
This study supports anecdotal evidence regarding the role of sleep position in KCN. Larger studies, including polysomnography, are warranted to support sleep interventions/education in patients with KCN.
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