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Sonya Thomas, Cecily E. Hamill, Inna Z. Marcus, Kristy G. Ahrlich, Nils A. Loewen; Visual Field Asymmetry And Sleep Position In Low Pressure Glaucoma. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5055.
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To investigate a hypothesized correlation between sleep position and interocular visual field asymmetry in low pressure (LPG) and high pressure (HPG) open angle glaucoma . LPG patients have more frequent asymmetric visual field loss and a predominance of left sided loss when compared with HPG patients, but no asymmetric risk factors have been identified to date.
28 LPG and 46 HPG patients were identified via chart review and the visual field index (VFI) was calculated for the most recent reliable exam with the Humphrey Visual Field Analyzer II-i with Guided Progression Analysis. Applying the criteria established by the Low Pressure Glaucoma Treatment Study Group (LoTGS), subjects were considered LPG if they had an untreated pressure of <22mmHg in both eyes. Participants completed a survey about their sleep position which characterized their position as predominantly side, prone, supine or unknown. Patients who chose side as their primary position were further characterized as sleeping mostly on the left side, right side or both sides. All analyses were performed using the Wilcoxon Rank-sum test.
The interocular difference in VFI (Right-Left ) was significantly different (p= 0.045) between LPG and HPG patients. LPG patients had a worse VFI in their left eye while HPG had near equivalent damage in the left and right eye (mean VFI difference: LPG= 6.0, HPG= -0.19). Right sided sleepers had a significantly lower right VFI compared to non-right sided sleepers (p= 0.044). No significant difference was found for left sided sleepers and the left VFI. More right sided sleepers were asymmetric (VFI Difference >5%) than non-right sided sleepers (p = 0.009). Lateral sleepers had a significantly larger VFI difference compared to non-lateral sleepers (p=0.03). Subjects with a worse right VFI (positive VFI difference) had a higher rate of asymmetry than subjects with a worse left VFI (p=0.002).
Our data replicates previous findings of greater frequency of asymmetry and left sided predominance of visual field loss in LPG. It also shows that sleep position is an important factor since patients who slept on their right side have greater VFI asymmetry and a tendency for the right VFI to be worse. We are currently using portable sleep position monitors to gather objective data on sleep position in subjects with asymmetric VFI.
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