To investigate the relationship between preferred sleeping position and asymmetric visual field (VF) loss in open-angle glaucoma (OAG) patients.

Retrospective, cross-sectional study.

Six hundred and ninety-two (692) patients with bilateral normal-tension glaucoma (NTG) or high-tension glaucoma were consecutively enrolled. A questionnaire to determine the preferred sleeping position was administered to each patient. Asymmetric VF loss was defined as a difference in mean deviation between the 2 eyes of at least 2 dB. According to these values, the better eye and worse eye were defined. Among the patients with asymmetric VF loss, the numbers preferring the worse eye–dependent lateral decubitus position and the better eye–dependent lateral decubitus position were compared.

Among the enrolled patients, 309 (60.6%) with NTG and 121 (66.5%) with high-tension glaucoma had asymmetric VF between the 2 eyes. Among the 309 NTG patients, 100 (32.4%) preferred the lateral decubitus position. Of these, 66 (66.0%) preferred the worse eye–dependent lateral decubitus position (P = .001). Among the 121 high-tension glaucoma patients, 32 (26.4%) preferred the lateral decubitus position, and of these, 23 (71.9%) preferred the worse eye–dependent lateral decubitus position (P = .013).

Our results suggest that the sleep position habitually preferred by glaucoma patients may be associated with greater VF loss.