A randomized controlled trial to evaluate which treatment protocol in selective laser trabeculoplasty that is most optimal in terms of efficacy and safety.
A randomized controlled trial in which individuals scheduled for SLT are randomized to one of four treatment protocols, which represent the most common variants of the treatment in clinical use. Treatment is performed either at 360 degrees or 180 degrees and with a laser energy level either 0,1 millijoules (mJ) below the microbubble formation limit ("low" energy) or at a level that gives microbubbles at 50-75% of laser effects ("high" energy). This gives four treatment arms: 180/low, 180/high, 360/low and 360/high. Group allocation is masked for the patient and is coded in the records. The results for short and long term treatment effects are compared between the groups, as well as the complication rate and postoperative discomfort.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
400
A drop of Pilocarpine 4% is administered to the eye 20 minutes before SLT. Immediately before SLT a drop of Tetracaine hydrochloride 1% is administered. Selective laser trabeculoplasty is conducted through a Latina lens, in a fashion determined by randomization to a study arm (see description).
Ogonkliniken, Sodra Alvsborgs Sjukhus
Borås, Västra Götaland County, Sweden
Ogonkliniken, Sahlgrenska Universitetssjukhuset
Mölndal, Västra Götaland County, Sweden
Ogonkliniken, Skaraborgs Sjukhus
Skövde, Västra Götaland County, Sweden
Ogonkliniken NU-sjukvarden
Uddevalla, Västra Götaland County, Sweden
Change in intraocular pressure (IOP)
The IOP is measured with a Goldmann Applanation Tonometer (GAT) three times before SLT and then at regular intervals after the procedure. The reduction is registered and analyzed in absolute (mmHg) and relative (percent of the IOP before SLT) measures. Measurement of IOP is planned 1, 3, 6 and 12 months post SLT, and thereafter every six months for 3 years after SLT. The study is conducted in a regular clinical setting and the above mentioned times might be delayed. If target pressure is not achieved, measurements will be planned at shorter intervals, according to a specified algorithm, due to safety reasons.
Time frame: Before SLT and thereafter regularly for 3 years
Achievement of 20% reduction in IOP
See Outcome 1. Analysis of differences between the study arms will also be conducted measuring the proportion of eyes achieving 20% reduction in IOP or more at different time points in each group.
Time frame: For 3 years
Survival (no additional intervention)
Kaplan-Meier survival analysis will be conducted, measuring the proportion of eyes that stay in the study groups but do not receive any further IOP-lowering intervention (medical, surgical or laser).
Time frame: For 3 years
Survival (SLT allowed)
See Outcome 3. Kaplan-Meier survival analysis is performed the same way, but additional SLT-treatment will not be judged as failure.
Time frame: For 3 years
Pain perioperatively: on a scale
The patient will grade perioperative pain on an arbitrary scale between 0 (no pain) and 4 (maximum pain) on a written protocol.
Time frame: Immediately after treatment
Pain postoperatively: on a scale
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The patient will grade post-operative pain on an arbitrary scale between 0 (no pain) and 4 (maximum pain) on a written protocol, also stating the duration of pain.
Time frame: During the first month
Light sensitivity postoperatively
The patient will grade post-operative sensitivity to light on an arbitrary scale between 0 (no difference) and 4 (very intense sensitivity to light) on a written protocol, also stating the duration of light sensitivity.
Time frame: During the first month
Impairment of vision postoperatively
The patient will grade post-operative impairment of vision on an arbitrary scale between 0 (no difference) and 4 (cannot see ones own hand) on a written protocol, also stating the duration of vision impairment.
Time frame: During the first month
Redness postoperatively
The patient will grade post-operative redness of the eye on an arbitrary scale between 0 (no difference) and 4 (very intense redness) on a written protocol, also stating the duration of redness.
Time frame: During the first month
Flare (inflammation measurement of the anterior chamber)
15 participants from each treatment arm (60 in total, randomized in a separate block after informed consent) will undergo measurement with a Laser Flare Meter.
Time frame: Pre-operatively and then one day, one week and one month post-operatively.
Adverse events
The type and frequency of adverse events will be recorded and analyzed in each of the study arms.
Time frame: 3 years (although adverse events, if any, are anticipated to emerge in the first post-operative days or weeks).