Findings from a study recently published in JAMA Ophthalmology evaluated the responsiveness to repeat selective laser trabeculoplasty (SLT) in patients with newly diagnosed open-angle glaucoma (OAG) and ocular hypertension (OHT).
Give me some background.
There is a growing body of literature that recommends SLT as a first-line treatment for OAG and OHT.
- However, regardless of their initial response, it remains unclear whether repeat SLT can be recommended in these patients.
Go on …
The Laser in Glaucoma and Ocular Hypertension (LiGHT) trial in China (LiGHT China) was an unmasked, single-center randomized controlled trial that compared health-related quality of life (HRQL) measures.
- Patient population: Newly diagnosed patients with OAG and OHT who were first treated with SLT vs those treated with topical medications alone
In the original LiGHT China, a total of 771 previously undiagnosed OAG and OHT patients were included.
- Note: Patient recruitment took place between March 2015 and January 2019.
Now, talk about this study.
Investigators performed a post hoc analysis of LiGHT China wherein they analyzed 180 newly diagnosed OAG eyes from 105 participants (mean age 45.6 years, 44.8% female) who underwent repeat SLT at the Zhongshan Ophthalmic Center, Guangzhou, China.
- Study period: March 2015 to April 2023
And the setup?
Standard SLT was the primary treatment and repeat SLT was the first choice of treatment escalation, regardless of the patient’s initial response to the procedure.
The maximum reduction in IOP within 2 years after initial SLT and repeat SLT was used to identify potential patients who did not respond to the treatment.
- A poor response to SLT was defined if the maximum reduction in IOP was < 20% from baseline during follow-up.
Findings?
Initial SLT and repeat SLT were both associated with a reduction in IOP:
- Initial SLT: 4.5 mmHg, 95% confidence interval (CI) 3.9-5.1 mmHg, P < 0.001
- Repeat SLT: 3.3 mmHg, 95% CI 2.7-3.8 mmHg, P < 0.001
The mean (standard deviation [SD]) IOP after repeat SLT was 15.8 (3.4) mmHg, similar to 16.0 (4.0) mmHg after initial SLT.
- Difference: -0.4 mmHg, 95% CI -1.0-0.3, P = 0.24
The duration of effect after repeat SLT was longer than after initial SLT (1,043 days vs. 419 days, hazard ratio [HR] 0.38, 95% CI 0.29-0.50, P < 0.001).
How did participants respond to repeat SLT?
IOP reduction after initial SLT was uncorrelated with that after repeat SLT, and 153 eyes (85.0%) responded favorably to SLT at least once.
A subset of 27 eyes (15.0%) was identified as potentially nonresponsive and was associated with certain baseline traits, such as:
- Older age: Mean (SD) age: 54.1 (12.5) years vs. 44.2 (14.2) years; difference: 10.5 years, 95% CI 2.9-18.1, P = 0.009
- Female sex: 27.5% difference, 95% CI 3.6-51.5, P = 0.03
- Lower IOP: -3.2 mmHg difference, 95% CI -5.2 to -1.3 mmHg, P = 0.001)
Expert opinion?
Per the study authors, the study demonstrated that an IOP reduction was observed from only one SLT intervention, especially at an isolated mark, and was not predictive of the effectiveness of repeat SLT.
“This is likely because various uncertain factors can influence the real effect, and IOP at an isolated time mark should not be considered representative,” they wrote.
They added that most participants had the potential to experience a considerable reduction in IOP, even if they did not initially achieve it.
Anything else?
An invited commentary also published in JAMA Ophthalmology noted that:
- The study primarily focused on IOP recorded at 2 months after both initial and repeat SLT.
- The authors explained that this “does not signify even medium-term success” and “allows the best IOP to be the result rather than consistent achievement of the selected target IOP.”
- With angle-based glaucoma surgeries becoming more widely used, the potential impact of prior SLT on the efficacy of these interventions requires further research.
Take home.
These findings suggest that SLT effectively lowered IOP in most cases of OAG and OHT as well as supported the consideration of repeat SLT regardless of initial response.
Further, potential non-responders to SLT could be identified early with certain baseline characteristics.