Corneal properties may be significant risk factors for glaucoma progression
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Investigators found that a thin cornea and low corneal hysteresis have high significance in understanding which patients are at greater risk of glaucoma progression even with well-controlled IOP, according to a recently published study.
“The evaluation of predictive factors for progression in eyes with seemingly well-controlled IOP is important to identify those eyes in which more aggressive interventions, aimed at even lower IOP levels, may be desired,” Bianca N. Susanna, MD, researcher at the Duke University Eye Center, and colleagues wrote.
Researchers studied 445 eyes of 327 patients with glaucoma undergoing treatment. A comprehensive ophthalmologic examination was performed on each participant every 6 months, and IOP measurements were recorded. Corneal hysteresis measurements were recorded at baseline using the average from three measurements of each eye along with each eye’s central corneal thickness (CCT).
Findings showed that of the 445 eyes there were 179 that had IOP measurements below 18 mm Hg and were considered to have well-controlled IOP. Of these patients, 42 eyes had progressive visual field loss, and 137 of the eyes remained stable. Those that progressed had lower corneal hysteresis and CCT than the stable eyes.
For every 1 standard deviation of increase in corneal hysteresis (1.5 mm Hg) or decrease in CCT (41 mm), there was an increase of 65% in the risk of developing visual field loss and 56% in the risk of visual field progression.
“Thinner CCT and lower [corneal hysteresis] were risk factors for progression in these patients,” Susanna and colleagues wrote. “Our findings support investigating these characteristics in treated patients and patients with otherwise progressing disease.”
According to the study, it is reasonable to take corneal hysteresis and CCT into consideration when treating patients with glaucoma. – by Erin T. Welsh
Disclosure: Susanna reported no relevant financial disclosures. Please see the full study for all the other authors’ financial disclosures.
Perspective
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Mark Eltis, OD, FAAO
Glaucoma is not always a simple disease to diagnose or effectively treat. Those of us whose practice focuses on this condition can attest to that. Over the years I’ve attended many lectures by top experts who acknowledge caring for patients who they eventually realized were misdiagnosed or mismanaged. It’s no surprise that new research is showing that glaucomatous vision loss can progress even when IOP seems to be well controlled.
Susanna and colleagues, in their prospective cohort study, have shed some light on why this might be. They found that corneal hysteresis and corneal thickness are risk factors in disease progression in patients with well controlled IOP.
Thankfully, glaucoma is generally a slow-moving condition. Technology helps mitigate the mysterious nature of the disease, but what is really needed is humility, vigilance and frequent follow-up. Our understanding of glaucoma is evolving, and it seems that the ability to withstand pressure as well as corneal properties and other as-yet-undiscovered factors may be more important predictors of outcome than snapshots of IOP. Like in real life, it’s not the amount of pressure we are under but how we deal with it that seems to matter.
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