An international team of researchers recently discovered a novel way to formulate a patient’s gonioscopy score to help predict the expected intraocular pressure (IOP) after cataract surgery.

They looked at 188 eyes from 137 patients with or without glaucoma, all of which had cataract surgery. Preoperatively, the researchers gathered a gonioscopy score that was a sum of the Shaffer gonioscopy grading in four quadrants (with a range of zero to 16). They then adjusted for age, sex and preoperative IOP.

At six months post-procedure, the mean IOP reduction was 3.0 ±2.6mm Hg. Further analysis revealed preoperative IOP, gonioscopy score, anterior chamber depth (ACD) and the IOP/ACD ratio were all associated with IOP reduction. The researchers found that when the calculated gonioscopy score was zero, the expected post-op IOP reduction was 5.64mm Hg. A score of 16 led to a expected reduction of 1.76mm Hg post-procedure.

“However, the variability of the gonioscopy score for predicting IOP reduction is high,” the researchers warn. “Therefore, it is not advisable to predict the IOP reduction after cataract surgery based on the gonioscopy score only.”

One characteristic to consider is preoperative ACD, as the study also shows it was statistically significant for predicting IOP reduction.

“This score could guide the clinician in the direction of IOP change after cataract surgery, rather than serve as a predictor of the exact amount of IOP change of each individual patient,” the researchers conclude. “These findings should also encourage clinicians to do more gonioscopy in their glaucoma patients who are having cataract surgery, which may help to reduce the percent of glaucoma patients who have not undergone a gonioscopy exam.”

Perez CI, Chansangpetch S, Feinstein M, et al. Novel gonioscopy score and predictive factors for intraocular pressure lowering after phacoemulsification. J Glaucoma. 2018;27(7):622-6.