Primary angle-closure glaucoma (PACG) is one of the major causes of blindness affecting more than 20 million patients worldwide. The goals of this observational cohort study are to investigate the 20-year incidence of PACG in Chinese population aged 50 years and to develop prediction models for the long-term risk of progression from primary angle-closure suspect (PACS) to PACG.
Primary angle-closure glaucoma (PACG) is potentially a devastating disease, responsible for half of glaucoma-related blindness worldwide, especially in East Asia. Primary angle-closure suspect (PACS), which is characterized by appositional angle closure, is the earliest stage of primary angle closure diseases and can finally progress to PACG. Thus, identifying PACS eyes at risk of angle closure is crucial for its management. However, the natural history of progression from PACS to PACG and its prediction models are still limited in long-term longitudinal studies. Meanwhile, visual impairment poses a significant global public health burden along with the accelerating trend of aging, it is imperative to further evaluate the visual impairment among the elderly population. The Liwan Eye Study was a population-based study initiated in 2003. The decision to select Liwan District for the survey was taken because of its stable, older population and a socioeconomic profile representative of Guangzhou as a whole. At baseline, 1405 eligible subjects aged 50 years and older completed a comprehensive eye examination and a questionnaire interview regarding education, income, hypertension and diabetes mellitus. To improve the monitoring of PACS and prevent vision loss associated with PACG, the purposes of this observational cohort study are to investigate the 20-year incidence of PACG in Chinese population aged over 50 years, develop prediction models that include eye characteristics, demographic features, ocular imaging characteristics, and genetic factors for the long-term risk of progression from PACS to PACG. Moreover, we aim to investigate the 20-year change in visual impairment and associated factors.
Study Type
OBSERVATIONAL
Enrollment
600
Primary angle-closure suspect (PACS), which is characterized by appositional angle closure, is the earliest stage of primary angle closure diseases and can finally progress to primary angle-closure glaucoma (PACG).
The 20-year incidence of primary angle-closure glaucoma (PACG) in Chinese population aged over 50 years
The presence of PACG is determined by visual acuity, intraocular pressure, anterior segment optical coherence tomography (AS-OCT). The incidence of PACG is defined as the number of new cases of PACG divided by the number of individuals without PACG at baseline.
Time frame: 20-year
The development of prediction models for the long-term risk of progression from primary angle-closure suspect (PACS) to primary angle-closure glaucoma (PACG)
Prediction model performance was assessed by discrimination and calibration.Discrimination was evaluated using the ROC curve and area under the curve (AUC) or C-statistics. Calibration was visualized through calibration plots and evaluated using the Hosmer-Lemeshow goodness-of-fit test (HL test).
Time frame: 5-year, 10-year, 20-year
The 20-year incidence of visual impairment in Chinese population aged over 50 years
Visual acuity (VA) will be measured using the Early Treatment Diabetic Retinopathy Study (ETDRS) logMAR illiterate E VA chart. Visual impairment is defined as VA \<20/60 \& ≥20/400, and blindness is defined as VA\<20/400 in the better-seeing eye.
Time frame: 20-year
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