Corneal Hysteresis May Identify Glaucoma, Increased Disease Progression Risk

Corneal hysteresis may help clinicians to identify patients with glaucoma and individuals with an increased risk for disease progression, according to a review published in Ophthalmology. According to the report, lower values of this corneal biomechanical parameter may be associated with glaucoma and glaucomatous progression.

The American Academy of Ophthalmology reviewed 13 cross-sectional or prospective studies published between 2006 and 2019 that included the search terms “corneal hysteresis” and “glaucoma.” 

In studies that reported group averages, corneal hysteresis levels were generally lowest among patients with pseudoexfoliative glaucoma (PXG; mean range, 6.8-8.0 mm Hg), followed by primary angle-closure glaucoma (PACG; mean range, 6.8-9.3 mm Hg), primary open-angle glaucoma (POAG; mean range, 7.7-9.5 mm Hg), normal tension glaucoma (NTG; mean range, 8.0-9.0 mm Hg), pseudoexfoliation syndrome (PXS; mean range, 8.2-8.5 mm Hg), and ocular hypertension (OHT; mean range, 9.2-10.2 mm Hg). Among the control groups in these studies, corneal hysteresis ranged from 9.4 to 10.6 mm Hg.

The highest intraocular pressure (IOP) was noted in PACG (mean range, 16-31.6 mm Hg), followed by POAG (mean range, 14.7-23.6 mm Hg), OHT (mean range, 22.2-22.3 mm Hg), PXG (mean range, 15.7-17.5 mm Hg), PXS (mean range, 13.4-15.8 mm Hg), and NTG (mean range, 13.2-14.6 mm Hg), the report shows. Participant IOP was significantly higher among patients with POAG compared with individuals in the control group in 4 of 5 studies that assessed this comparison.   

One longitudinal study reported that corneal hysteresis was associated with visual field progression. And for every 1 mm Hg decrease in corneal hysteresis, the visual field index declined by an additional 0.25% per year (P <.001). Another study found that every 1.5 mm Hg decrease in corneal hysteresis was associated with a 65% increased risk for visual field loss. A third study showed a correlation between a 1 mm Hg decrease in corneal hysteresis with a 0.13 μm yearly retinal nerve fiber layer thickness loss (P =.011).

However, it remains unclear whether corneal hysteresis may be useful in glaucoma diagnosis or risk stratification. 

“Corneal hysteresis is a novel clinical parameter representing a response of ocular tissue to transient compression and release by an air-puff tonometer,” according to the researchers. “Although the interpretation of this measurement is complex and influenced by multiple factors, including elasticity and viscosity, [corneal hysteresis] appears to provide additional information that could be useful for the clinical assessment of glaucoma suspects and patients.”

Study limitations include a retrospective nature and lack of uniformity in study designs. 

Disclosure: Multiple study authors declared affiliations with biotech, pharmaceutical, and/or clinical research organizations . Please see the original reference for a full list of authors’ disclosures.