Micro pulse transscleral laser treatment (MP-TLT) is a relatively new method to reduce the intraocular pressure (IOP) in glaucoma. New recommendations regarding the treatment protocol has recently been developed and was published 2022. The overall objective is to evaluate the efficacy and safety of the proposed treatment method in an independent study. In addition, the outcome of MP-TLT in patients with pseudoexfoliation glaucoma, which is relatively common in the Nordic countries, and primary open angle glaucoma will be studied separately. The IOP change over the course of one year will be monitored, as well as success rate and survival. Further, patient-reported discomfort from the treatment and the occurrence of any adverse events or complications will be studied.
Forty patients scheduled for MP-TLT by their ophthalmologist will be recruited. One eye per patient is included, based on randomization, even if both are treated. MP-TLT will be performed according to the current recommendations. Baseline IOP will be calculated as the mean of three separate measurements taken on different days preoperatively. IOP will then be measured 1 week, 1 month, 3 months, 6 months and 12 months after MP-TLT. The central corneal thickness (CCT), the central retinal thickness (CRT), anterior chamber flare and the visual field (HFA 24-2 faster) will also be measured preoperatively and during follow up. In accordance with the World Glaucoma Association guidelines, no adjustment for multiple comparisons is planned in this study.
Study Type
OBSERVATIONAL
Enrollment
40
Patients will receive topical anesthesia with tetracaine hydrochloride 1% three times, 5 minutes apart. Then, lidocaine gel 2% will be applied on the surface of the eye and refilled as needed for 10 minutes, as well as manipulated for a good coverage.
Micro pulse transscleral laser treatment will be performed with the Iridex CycloG6 laser with the revised P3 probe, according to the recent consensus recommendations. In brief, this includes MP-TLT with 2500 mW, 31.3% duty cycle, four 20 second sweeps per hemisphere, avoiding the 3 and 9 o'clock meridians and sectors with scleral thinning.
Department of Ophthalmology, Skaraborg Hospital
Skövde, Västra Götaland County, Sweden
Department of Ophthalmology, NU Hospital Group
Uddevalla, Västra Götaland County, Sweden
Relative IOP change (percent)
Relative IOP (intraocular pressure) change (percentage relative to baseline) for the entire study population. "Last observation carried forward" will be used in cases with treatment escalation or reduction during follow up. Patients with peroral glaucoma treatment at baseline are not included in this analysis.
Time frame: 6 months
Relative IOP change (percent) for POAG and PXFG eyes separately
Relative IOP change (percentage relative to baseline) for the eyes with a diagnosis of primary open angle glaucoma, or pseudo exfoliative glaucoma, respectively. "Last observation carried forward" will be used in cases with treatment escalation or reduction during follow up. Patients with peroral glaucoma treatment at baseline are not included in this analysis.
Time frame: 6 months
Perioperative pain on a visual analogue scale (VAS)
The patient will report pain during MP-TLT treatment on a VAS immediately after surgery. A 10 cm horizontal line without markings will be presented. One end of the line represents "no pain" and the other "worst imaginable pain". The patient marks the position on the scale that corresponds to the level of perceived pain. The number of millimeters from the "no pain" end is the result. Higher is worse. If there was a need for supplementary anesthesia, the grading applies to the experience before supplementation.
Time frame: Immediately after surgery
Success proportion after 12 months
Eyes will be graded with either "success" or "failure" after one year of follow up. Definition of success (all must be fulfilled): * Reduction of the IOP by at least 20% compared to baseline and/or reduction in pharmacological glaucoma treatment. * IOP ≥ 6 mmHg * No additional IOP reducing intervention performed after MP-TLT.
Time frame: 12 months
Survival
Kaplan-Meier survival analysis regarding achievement and maintenance of "success" as defined above.
Time frame: 12 months
Relative change (percent) of the IOP 1 week, 1 month, 3 months and 12 months after MP-TLT.
IOP change relative to baseline 1 week, 1 month, 3 month and 12 months after MP-TLT. "Last observation carried forward" will be used in cases with treatment escalation or reduction during follow up. Patients with peroral glaucoma treatment at baseline are not included in this analysis.
Time frame: 12 months
Postoperative pain on a VAS 1 hour, 5 hours, and 24 hours postoperatively
Postoperative pain on a VAS 1 hour, 5 hours, and 24 hours postoperatively. See above for further description.
Time frame: 1 hour, 5 hours, and 24 hours postoperatively
Patient reported discomfort on an arbitrary scale
The patients will report peri- and postoperative pain, postoperative light sensitivity, visual impairment and hyperemia. The scale goes between 0 (no sensation) and 4 (worst imaginable). The scale was developed for the OSLT trial (NCT03798223). Comparisons will be made with the results from that trial.
Time frame: 1 month
Change in central retinal thickness (CRT) postoperatively
The thickness in the central retinal field will be measured with optical coherence tomography (OCT) at baseline and 1 week, 1 month and 3 months postoperatively. The relative change (percent) will be calculated for each time point.
Time frame: 3 months
Change in central corneal thickness (CCT) postoperatively
The central corneal thickness (CCT) in the thinnest point will be measured with Pentacam at baseline and 1 week and 1 month postoperatively. The relative change (percent) will be calculated for each time point. Applies only to NU patients (one of the centers).
Time frame: 1 month
Change of flare in the anterior chamber postoperatively
Flare in the anterior chamber will be measured with a Kowa laser flare meter at baseline and 1 week and 1 month postoperatively. The relative change (percent) will be calculated for each time point. Applies only to SkaS patients (one of the centers).
Time frame: 1 month
Change in visual field index (VFI) during follow-up
The visual field will be assessed with a Humphrey field analyzer (HFA) 24-2 faster at baseline and then 1 and 12 months postoperatively. The change in VFI, expressed in percentage points, will be calculated for each time point.
Time frame: 12 months
Adverse events
Suspected adverse events will be registered.
Time frame: 12 months
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