Surgical Outcome Of Carbon Dioxide Laser Assisted Sclerectomy Surgery (Class): Pilot Study In Thailand

Background: Carbon dioxide laser assisted sclerectomy surgery (CLASS) is one of non-penetrating glaucoma surgery, which is a minimal invasive glaucoma surgery(MIGS) in its concept of enhancing the natural aqueous outflow pathway with no need to puncture into the eye and minimal side effect of post operative complication in both short term and long term.

Purpose: To study surgical outcome of Carbon dioxide laser assisted sclerectomy surgery (CLASS) in uncontrolled IOP glaucoma patients

A pilot study of uncontrolled IOP glaucoma patients in glaucoma clinic at Mettapracharak hospital who underwent CLASS.

CO2 laser was applied instead of blade to de-roof the Schlemm's canal wall and remove juxtacanalicular trabecular meshwork and allow aqueous humor to drain through the  trabeculo-descemet window.

We included uncontrolled IOP glaucoma 12 eyes from 10 patients, with juvenile opened angle 6 eyes, primary open angle glaucoma 1 eye, secondary opened angle glaucoma 3 eyes and secondary closed angle 2 eyes. Surgical technique were describing, sub-conjunctival Mitomycin C was injected, limbal peritomy was performed at superior quadrant, scleral flap size 5x5 mm was performed, CO2 laser was ablated sclera creating scleral lake size 2x4 mm at posterior part and intact trabeculo-descemet membrane same size at anterior part and conjunctival was sutured. Surgical outcomes were defined as complete success with IOP<21 mmHg, qualified success with IOP<21mmHg with medication and failure with 5>IOP>21 mmHg.

Average age was 53.5 + 10.01 years old. Baseline and 6 months follow-up visit of parameters were following, LogMAR visual acuity: 0.81 + 0.8 vs. 0.88 + 0.8, p=0.361, IOP: 25.75 + 9.50 vs.17.70 + 7.68 mmHg, p=0.082, mean anti-glaucoma medication type 3.12 + 1.19 vs.1.92 + 1.31, p=0.035*. Almost eyes were severe glaucoma stage. At 6 months both visual field and retinal nerve fiber layer thickness parameters were not different from baseline. Surgical success rates were complete success16.7%, qualified success 58.3% and failure 25%. Secondary closed angle glaucoma in etiology was associated with failure.

CLASS is an easier and shorter learning curve of non-penetrating glaucoma surgery with same concept as MIGS with minimal side effect and short recovery period with 75% success rate at 6 months follow up. CLASS would be considered as a procedure of choice in uncontrolled IOP opened angle glaucoma patients.