Five-year risk of progression of primary angle closure to primary angle closure glaucoma: a population-based study

Objective: To report the 5-year progression to primary angle closure glaucoma (PACG) in a population-based cohort of primary angle closure (PAC) subjects. Methods: A total of 37 patients diagnosed as PAC during a population-based study in 1995 were invited for re-examination in 2000. Patients underwent a complete ophthalmic examination including ocular biometry. Progression to PACG was based on optic disc damage and field defects on automated perimetry. Results: In all, 28 of 32 PAC subjects who could be contacted presented for examination. Eight (28.5%; 95% CI 12 - 45%) had progressed to PACG; two of seven with appositional and six of 21 with synechial closure. All were advised laser peripheral iridotomy (LPI) in 1995; one of the nine who underwent LPI progressed compared to seven of 19 who refused LPI. Four of those originally diagnosed with appositional closure developed peripheral anterior synechiae. One eye of a person previously diagnosed with appositional PAC was reclassified as a primary angle closure suspect ( PACS). There was no significant difference in biometric parameters between those who progressed and those who did not. None developed acute PACG or blindness due to glaucoma. Conclusion: In this population-based study of primary angle closure, the 5-year incidence of PACG was eight patients ( 28.5%; 95% CI 12 - 45%). We were unable to identify any features that predicted progression.