Glaucoma Status, Subtype Detected Through Corneal Biomechanical Changes

Evaluating corneal biomechanical parameters may be instrumental in determining glaucoma status, severity and subtype, according to a study published in the Annals of Medicine and Surgery.

Researchers compared data from 229 eyes of patients enrolled in the prospective, cross-sectional study. Participants were stratified into 1 of 5 groups, based on glaucoma subtype, consisting of eyes of healthy control individuals (n=70; 42.9% men; mean age, 51 years), eyes with pseudoexfoliation glaucoma (PEXG; n=26; 69.2% men; mean age, 68 years), eyes with primary angle closure glaucoma (PACG; n=46; 41.3% men; mean age, 63 years), eyes with primary open-angle glaucoma (POAG; n=66; 63.6% men; mean age, 62 years), and eyes with normal tension glaucoma (NTG; n=21; 42.9% men; mean age, 63 years). All patients underwent a comprehensive eye exam, intraocular pressure (IOP) measurements, and corneal hysteresis measurements.

Overall, patients with glaucoma demonstrated lower corneal resistance factor (9.4 vs 11.1; P <.001), thinner central corneal thickness ( 521 vs 540 mm; P =.016), and higher C/D ratio (0.60 vs 0.42; P <.001) compared with control individuals. Minor increases in pachys, radius, and pachys slope were also noted among patients with glaucoma, as well as decreased highest concavity (HC) deformation amplitude, HC deflection amplitude, HC deflection area, deflection amplitude max, dArc length max, max inverse radius, and integrated radius. 

Corneal biomechanical parameters also predicted glaucoma type, according to the report. Patients with PACG had lower anterior chamber depth (ACD) and higher central corneal thickness (CCT) compared with other glaucoma subtypes. Lower CCT and higher C/D and white-to-white (WTW) were noted among patients with NTG. Patients with PEXG demonstrated the lowest corneal hysteresis and corneal resistance factor.  

“The utilization of corneal biomechanical features in evaluating glaucoma and its progression has received particular attention,” according to the study authors. “Some changes in corneal biomechanical parameters are specific to the subtypes of the disease. Moreover, the severity of corneal biomechanical changes can play an essential role in response to the medical or surgical treatment of such patients.”

Study limitations include a retrospective nature, an unequal number of patients in subgroups, and a small sample size.