Subthreshold nanosecond laser safe but not beneficial in age-related macular degeneration
Treatment with subthreshold nanosecond laser (SNL) does not appear to effectively slow down the rate of progression to late age-related macular degeneration (AMD) in patients with intermediate disease, according to the results of the LEAD trial.
However, SNL may confer benefits for AMD progression in patients without coexistent reticular pseudodrusen (RPD) but may be inappropriate in those with RPD.
A total of 292 individuals (average age 70 years; 73.6 percent female; 47.3 percent past or current smokers) with bilateral large drusen and without signs of atrophy were randomized to receive SNL (n=147) or sham treatment (n=145) to the study eye at 6-monthly intervals. In the study eye, the median best-corrected visual acuity (BCVA) was 83 letters, with 33.2 percent of the participants having retinal pigment epithelium (RPE) pigmentary abnormalities and 24.0 percent having RPD.
The primary efficacy outcome of time to develop late AMD, defined by multimodal imaging, did not significantly differ between SNL and sham treatment (adjusted hazard ratio [HR], 0.61; 95 percent CI, 0.33–1.14; p=0.122).
Posthoc analysis, however, revealed that SNL slowed AMD progression for 222 participants (76.0 percent) without coexistent RPD at baseline (adjusted HR, 0.23; 0.09–0.59; p=0.002), but increased progression rate for 70 (24.0 percent) of those who presented with RPD (adjusted HR, 2.56; 0.80–8.18; p=0.112; p=0.002 for adjusted interaction).
Safety was assessed by adverse events.
No device-related serious adverse events were reported. However, a deep retinal haemorrhage was observed at the same location where the laser was delivered in the SNL treatment group in 10 participants (6.8 percent) on 11 occasions, but no such cases were documented in the sham treatment group. All haemorrhage cases were resolved without any untoward sequelae.
The present data warrant caution when considering SNL treatment in clinical phenotypes with RPD and should not be extrapolated to other short pulse lasers, researchers said.