This study followed the tenets of the Declaration of Helsinki and was approved by the Ethics Committee of the Eye Hospital of Wenzhou Medical University. All participants signed a written and informed consent.
Participants
Briefly, from March 2014 to September 2015, residents in three districts of Wenzhou (Lucheng, Longwan and Ouhai), Zhejiang, China, aged ≥50 years, and having specific risk factors for open-angle glaucoma (i.e. myopia, diabetes and family history of glaucoma) were screened for the WGSP.[18] Glaucoma suspects were invited for further examination, including questionnaires in the Eye Hospital of Wenzhou Medical University. Finally, 161 POAG patients (127, 78.9%, NTG) were consecutively enrolled.
Inclusion criteria
- POAG in at least one eye
- Asymmetric VF loss, i.e. at least 2-dB difference in mean deviation (MD) between the 2 eyes at the baseline[19]
- Patients signed the informed consent
Exclusion criteria
- Spherical diopter <-6.0 diopter
- History of retina photocoagulation, intraocular surgery (except uncomplicated cataract surgery), or penetrating ocular trauma
- Disease that may influence the IOP or VF test
- Unreliability of the VF test (>20% fixation loss, >15% false-positive, >15% false-negative)
- Any of the eyes used anti-glaucoma medication in recent 1 month.
Preferred sleeping position and preferred lateral decubitus
The sleeping position was asked through the question below at baseline, by a single trained doctor (XFP) who masked to the ophthalmic examination results. The patient’s preferred sleeping position (PSP) was defined as the sleeping position with the highest percentage. However, we consider there was no PSP if more than one sleeping position with the same high percentage.
The patient was defined as a right preferred decubitus position if he/she had higher percentage of right decubitus position than left decubitus position, even if supine or prone was the PSP. Vice versa for the left preferred decubitus position.
Question: What’s your sleeping position in the last one week? Please fulfill the time percentage before the sleeping position, and please be note the total percentage should be 100%
(1)__% right lateral decubitus position (2)__% left lateral decubitus position (3)__% supine position (4)__% prone position
Definition
POAG was defined if the eye met (1) to (3) items plus (4) and/or (5) item. (1) Elevated IOP without treatment; (2) Open anterior chamber angle (not occludable, no goniodysgenesis); (3) No history or signs of other eye disease. (4) Characteristic glaucomatous optic disc damage (such as enlarged vertical CDR >0.65, disc hemorrhage); (5) RNFL defect (localized or diffused) corresponding to glaucomatous VF defects.
NTG was defined as the POAG patients with an untreated IOP (Goldmann) ≤21 mmHg for any visit during the baseline and follow up.
The better eye was defined as the eye with a higher MD value at baseline, while the contralateral eye was defined as the worse eye.
Progression of POAG was defined according to one of the following criteria: (1) Glaucomatous experts’ judgment (YBL, SDZ); (2) The rate of progression (MD) <-1 db/year,[20] calculated by Humphrey Visual Field Analyzer (Zeiss Forum, Carl); (3) The Cirrus OCT GPA software analyzes data yielded upon the use of the optic disc cube200×200 mode. We considered that “Likely Loss” and “Possible Loss” reflected glaucomatous progression.
Statistical
Statistical analyses were performed using SPSS version 23.0 (SPSS Inc, Chicago, Illinois, USA). Data with normal distribution was presented as the mean ± 1 standard deviation. The parameters, such as baseline IOP, spherical equivalent, axial length, and result of VF and OCT testing using independent t tests between better eye and worse eye. c2 tests were used to analyze the count variables, such as number of preferred LDSP. A P value < 0.05 was considered to be significant difference.