Results of eye chart visual acuity test for the without-CPAP group (A) and with-CPAP group (B) are presented in bar graph.

<p>There is no significant difference between groups. Error bars  =  S.E.M.</p

Demographic and polysomnographic variables in all subjects.

<p>All values are presented as means ± S.E.M.</p

Pre and post sleep comparison of left and right corneal thickness of each group.

<p>Values are given as microns for corneal thickness (means ± S.E.M.).</p>*<p>p = 0.0025 very significant (t = 4.134 with 9 degrees of freedom). The comparison is between Pre-Sleep and Post-Sleep of left corneal thickness in without-CPAP group.</p>**<p>p< 0.0001 extremely significant (t = 9.257 with 9 degrees of freedom). The comparison is between Pre-Sleep and Post-Sleep of right corneal thickness in without-CPAP group.</p

Results of post-sleep questionnaire of “with-CPAP” (CPAP) and “without-CPAP” (wo/CPAP) groups.

<p>The questionnaire is made-up of four categories, which are Blurred Vision (BV) – panel A, Dimmer Vision (DV) – panel B, Clear Vision (CV) – panel C and Eye Discomfort (ED) –panel D. Statistically significant (i.e., accepted as p<0.05) p values are shown in the figure. Non-significant p values are not shown. The possible three answers to each of the categories are summarized as “Less answer” =  “Less”, “Same answer”  =  “SameMore” and “More answer”  =  “SameMore” to make an easy interpretation of data.</p

Visual acuity values of each patient.

<p>Values are given as Snellen units.</p

The Relationship Between Cpap Usage And Corneal Thickness

The purpose of this study was to determine whether there is a correlation between CPAP usage and corneal thickness in patients with sleep disordered breathing. Full-night polysomnography (PSG) recordings were collected. Ten patients had undergone PSG recordings with continuous positive airway pressure (CPAP), and seven patients had undergone PSG recordings without CPAP. We measured corneal thickness by ultrasonic pachymeter before sleep and ten minutes after waking. We also measured visual acuity with a routine ophthalmologic eye chart before and after sleep. We asked patients to fill out a post-sleep questionnaire to get their subjective opinions. In the without-CPAP group, corneal thickness increased significantly during sleep in both eyes (left, p = 0.0025; right, p0.05 for both left and right cornea). There was no significant difference in visual acuity tests (p>0.05 for both left and right eye) between the two groups. According to our results, there is a significant increase in corneal thickness in the without-CPAP group. Our data show that a low percentage of Rapid Eye Movement (REM) sleep may cause an increase in corneal thickness, which can indicate poor corneal oxygenation. In fact, many sleep-disordered breathing (SDB) patients have low REM. Since a contact lens may cause low corneal oxygenation, SDB patients with contact lenses should be monitored carefully for their corneal thickness.PubMedWoSScopu