Abstract
Purpose: :
To determine if head postures which may be adopted during sleep has an effect on intraocular pressure (IOP).
Methods: :
The design of this study is of a prospective observational case series. Adult subjects were recruited from general ophthalmology out-patient clinic visits for non-glaucoma conditions. Exclusion criteria for the study included glaucoma, ocular hypertension, other conditions leading to raised IOP, or inability to lie recumbent in the supine and left lateral decubitus position. IOP was measured using Tono-Pen XL® (Reichert Inc. NY, USA) for the left eye of each patient in the supine position. Immediately after, a second measurement was obtained in the left lateral decubitus head position. Measurements in both head positions were obtained with the patient lying on one soft pillow, then on one hard pillow. Patients remained awake during tonometry. One tonometry reading was obtained at each position and was only recorded if the average of four readings produced a statistical confidence interval of five percent. Results were analysed using the paired Student t test to compare means.
Results: :
There were twenty-three adult subjects of which fifteen (65.2%) were male. The mean age was 54 ± 16 years. Ocular diagnoses included cataracts (30%), dry eyes (26%), blepharitis (22%), vitreous syneresis (13%) and others (9%).The mean IOP in supine head position was 14.1 ± 3.3 mmHg. The mean IOP in left lateral head position was 17.1 ± 3.4 mmHg. A statistically significant mean IOP change from supine to left lateral head position was 3mmHg ± 1.3 (p<0.001). There was no difference in IOP in both head positions between hard and soft pillows.
Conclusions: :
Head positions which may be adopted during sleep had an effect of increasing IOP in the left lateral decubitus head position. Clinicians should be aware that this possible increase in IOP during sleep may lead to progression of glaucomatous optic neuropathy in patients despite target IOP being achieved with adequate treatment on examination at routine follow-up.
Keywords: intraocular pressure