An independent role of IOP fluctuations on glaucoma progression in patients with openangle glaucoma has been widely investigated but still remains controversial. Very little is known on the correlaton between IOP variations and angle-closure glaucoma.
In this well-conducted study by Cheung and colleagues, 240 Chinese PACG patients from a longitudial, observational study from a tertiary center in Hong Kong were included. Over a two-year follow-up, they had four annual IOP measurements and an average five visual field tests.
The investigators found a strong correlation between IOP fluctuation (defined as SD devided by mean IOP) and progression of visual field (both MD and VFI). Interestingly, these observation was found independent of mean IOP, although eyes with 'high-threshold' mean IOP and IOP fluctuation had more rapid VF progression.
One strength of this study includes the inclusion of wide glaucoma severities, whereas previous studies included either mostly advanced cases (AGIS) or early and untreated cases (EMGT).
A surprising finding which needs further research was the strong correlation between male sex and VF progression, independent of other parameters, in contrast to previous studies showing a higher risk for PACG in females.
The main limitation of this study, however, is the lack of continual IOP measurements. Recent reports using continual IOP monitoring have demonstrated the important daily and long-term variations of IOP in open-angle patients. As these technologies become more available in the near future, it is hoped that the role of IOP dynamics ono glaucoma development and progression will be better understood.