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IOP fluctuation may predict rate of visual field deterioration
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Fluctuating IOP was a significant and independent predictor for subsequent visual field deterioration in patients with primary angle closure glaucoma, according to findings published in the British Journal of Ophthalmology.
Carol Y. Cheung, PhD, and colleagues examined the relationship of IOP control with subsequent visual field deterioration in patients with primary angle closure disease (PACD).
“Robust evidence is lacking for defining the target IOP for PACD patients, and it’s still unclear whether lowering IOP to below the population mean helps in slowing the [visual field] deterioration in [primary angle closure glaucoma], which is structurally different from [primary open angle glaucoma] and may involve different disease processes,” Cheung, an assistant professor in the department of ophthalmology and visual sciences at the Chinese University of Hong Kong, and colleagues wrote.
The researchers studied 419 eyes of 240 Chinese patients with PACD. Mean IOP and IOP fluctuation were examined.
Cheung and colleagues found that greater IOP fluctuation was significantly associated with visual field deterioration, independent of mean IOP.
The researchers wrote that patients with high-threshold mean IOP and high-threshold IOP fluctuation had the most rapid visual field deterioration compared with eyes with low-threshold IOP fluctuation (P < .05).
In eyes with high-threshold mean IOP, patients with high-threshold IOP fluctuation had a faster rate of visual field deterioration compared with eyes with low-threshold IOP fluctuation (P = .01).
“We propose that for patients with PACD whose IOP is already within the normal range, it is worthwhile to consider minimizing IOP fluctuation by more close monitoring and careful titration of treatment according to each patient’s clinical course,” the authors said. – by Earl Holland Jr.
Disclosures: The authors report no relevant financial disclosures.
Perspective
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Derek MacDonald, OD, FAAO
While representing only one in four cases of glaucoma worldwide, PACD is responsible for half of glaucoma-related blindness. It is frequently un- or misdiagnosed and, as a result, inappropriately managed, with potentially catastrophic consequences.
In this study of treated PACD (predominantly manifest glaucoma), Cheung and colleagues provide both new information and critical reminders, augmenting and reinforcing our understanding of this devastating disease.
To begin, this was a treated cohort, emphasizing that while laser peripheral iridotomy (LPI) may alleviate pupillary block, it is not a definitive cure for angle closure glaucoma – post-LPI progression is common, and regular gonioscopy remains essential. As one may expect, cases with more extensive synechial closure and/or advanced disease at baseline progressed more rapidly. Further, IOP fluctuation at both high and low pressures proved to be an independent risk factor for progression. In fact, individuals with concurrently high and unstable IOPs lost visual field at a rate of about 1.5 dB/year.
If baseline damage is significant, severe visual impairment is imminent, underscoring the importance of simultaneously lowering and flattening the circadian IOP curve.
PACD is underdiagnosed and responsible for a disproportionate amount of severe vision loss. That must change, and it can start with optometry.
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