Selective laser trabeculoplasty for early glaucoma: analysis of success predictors and adjusted laser outcomes based on the untreated fellow eye

Abstract

BackgroundTo identify success predictors and to study the role of the fellow untreated eye as a co-variable for adjustment of intraocular pressure (IOP) outcomes following selective laser trabeculoplasty (SLT) in early open-angle glaucoma (OAG) patients.MethodsA case series was carried out. Patients with uncontrolled early OAG or ocular hypertension (inadequate IOP control requiring additional treatment) underwent SLT (one single laser session) performed by the same surgeon in a standardized fashion. The same preoperative medical regimen was maintained during follow-up for all patients. Post-treatment assessments were scheduled at week 1 and months 1, 2, and 3. In order to account for possible influence of IOP fluctuation on laser outcomes, post-laser IOP values of the treated eye of each patient were also analyzed adjusting for IOP changes (between visits variation) of the untreated fellow eye (adjusted analysis). Pre and post-laser IOP values were compared using paired t-test. Factors associated with the magnitude of IOP reduction were investigated using multiple regression analysis.ResultsA total of 45 eyes of 45 patients were enrolled. Mean IOP was reduced from 20.8 ± 5.1 to 14.9 ± 2.9 mmHg at month 3 (p < 0.001). Adjusted success rate (defined as IOP reduction ≥ 20%) was 64% and mean percentage of IOP reduction was 23.1 ± 14.3% at last follow-up visit. Considering unadjusted post-laser IOP values, it was found a 20% greater absolute IOP reduction (median [interquartile range] 6 mmHg [4–7] vs 5 mmHg [3–7]; p = 0.04), with a success rate of 76%. Although baseline IOP was significantly associated with both adjusted and unadjusted post-laser IOP reduction, a stronger association was found when unadjusted IOP values were considered (p < 0.001 and R 2 = 0.35; p < 0.001 and R 2 = 0.67, respectively). Age, mean deviation (MD) index, central corneal thickness and type of glaucoma were not significant predictors (p ≥ 0.150).ConclusionsIn this group of patients with early OAG or ocular hypertension, our short-term results confirmed SLT as a safe and effective alternative for IOP reduction. Although better outcomes were found in eyes with higher preoperative IOP, this effect was mitigated when results were adjusted to the fellow untreated eye (to the influence of between visits-IOP fluctuations).

Predictive Factors for Outcomes of Selective Laser Trabeculoplasty

“…Many studies have attempted to characterize potential predictive factors of success following SLT and we sought to assess current claims and to contribute currently unexplored predictive factors such as total energy delivery during treatment. Our results agree with the frequently reported finding that baseline IOP is a predictor of SLT success [16][17][18][19][20][21][22] , while factors such as patient age, PTM, and type of glaucoma are not 17,[20][21][22][23][24] . Some of the literature reports an association between heavily pigmented PTM and IOP spikes but we did not observe this in our population 9,24 .…”

Preservative-free fixed combination of tafluprost 0.0015% and timolol 0.5% in patients with open-angle glaucoma and ocular hypertension: results of an open-label observational study

“…Furthermore, the results of the subanalysis by baseline IOP levels in this subgroup of treatment-naïve patients confirmed that the greatest response to the preservative-free tafluprost/timolol fixed combination is obtained in patients with higher baseline IOP levels. This finding is consistent with the results of a meta-analysis of double-masked, controlled phase III studies with fixed combination products of prostaglandin and timolol published by Holló et al20 and for other treatment options like selective laser trabeculoplasty 21,22. In the study of Holló a similar reduction in IOP of ~32%–36% from untreated baseline IOP levels between 24 and 29 mmHg was reported 20.…”

“…This finding is consistent with the results of a meta-analysis of double-masked, controlled phase III studies with fixed combination products of prostaglandin and timolol published by Holló et al 20 and for other treatment options like selective laser trabeculoplasty. 21 , 22 In the study of Holló a similar reduction in IOP of ~32%–36% from untreated baseline IOP levels between 24 and 29 mmHg was reported. 20 Furthermore, this meta-analysis revealed that IOP reductions of up to 40% and beyond could be achieved for untreated baseline pressures of 31 mmHg or higher.…”

Comparison between 90‐degree and 360‐degree selective laser trabeculoplasty (SLT): A 2‐year follow‐up

“…Our results indicated that age, sex and exfoliation were not predictors of survival of treatment, in agreement with previous studies that also studied other variables. Ethnicity, type of glaucoma, family history of glaucoma, history of previous ALT, myopia, systemic disease (e.g., high blood pressure and DM), simultaneous eye drops (e.g., prostaglandins), visual function, pigmentation of TM, angle grade, phakic/pseudophakic state of lens and central corneal thickness were not found to be significant predictors either (Martow et al 2011;Leahy & White 2015;Chun et al 2016).…”