Low Intraocular Pressures, Uveitis Associated with Nonresponse to Laser Trabeculoplasty

Eyes with higher baseline intraocular pressures (IOPs) are more responsive to laser trabeculoplasty (LTP) than those with low IOPs, according to a recent American Journal of Ophthalmology study. The researchers also identified patients with uveitis, angle recession, and aphakia as less responsive.

Researchers examined records from the Intelligent Research in Sight (IRIS) Registry — an electronic health record (EHR)-based clinical data registry that includes data from 3120 practices across the United States — to determine factors that might predict the outcome of LTP treatment.

The study looked at records from 263,480 eyes, and identified 97,148 (36.9%) responders and 166,332 (63.1%) nonresponders. Among those with baseline IOPs greater than 24 mm Hg (34,271, 13.0%), 68.8% were responders. For those with a baseline IOP between 18 mm Hg and 24 mm Hg (123,261, 46.8%), 42.4% were responders. Finally, subjects with a baseline IOP lower than 18 mm Hg (105,948, 40.2%), 20.1% were responders.

Angle recession, uveitis, and aphakia significantly increased the odds of a nonresponse (ORs 2.46, 1.50, both P <.0001), 1.55 (P =.0259), while higher baseline IOP reduced the odds of a nonresponse (OR=0.60 for a 3 mm Hg increase). 

Some groups had increased odds of not responding, including: women compared with men (OR=1.22), patients aged 18 years to 39 years, compared with those 65 years to 79 years (OR=1.29), patients with diabetes compared with those without diabetes (OR=1.21), patients with other glaucoma diagnoses compared with those who were glaucoma suspect (OR=1.29) and patients who were pseudophakic, compared with those who were phakic (OR=1.23). 

Eyes which met current procedural terminology (CPT) code for LTP, were submitted to IRISon or before August 31, 2018 and had a glaucoma or glaucoma suspect diagnosis were included in the study. Eyes with no light perception and without visual acuity or pretreatment baseline IOP measurements before LTP were among those excluded.

Of the subjects, 74.4% were older than 65 years old (mean 71.4±11.7 years); 56.0% female; 64.8% white, 11.8% Black, 97.1% underwent a single LTP. While 73.1% of the diagnoses were primary open angle glaucoma, 18.6% were only glaucoma suspect. The mean baseline pre-LTP IOP was 19.1 mm Hg (±5.0 mm Hg) and mean number of pre-LTP medications was 2.1 (±1.5). 

Researchers classified “responders” as eyes whose first day’s mean IOP measurement on or after 8 weeks post treatment was at or below 80% of the pretreatment baseline IOP. “Nonresponders” were eyes whose first day’s mean IOP measurement was above 80% of the pretreatment baseline IOP in the same period.

To make the best use of LTP, researchers encouraged offering it as an initial therapy to patients with a high baseline IOP and as a way of decreasing the use of medication even when further IOP-lowering may not be required.

Reference

Chang TC, Parrish RK, Fujino D, Kelly SP, Vanner EA. Factors associated with favorable laser trabeculoplasty response: IRIS registry analysis. Am  JOphthalmol.Published online October 10, 2020. doi: 10.1016/j.ajo.2020.10.004