Effects of Photobiomodulation Therapy on Patients with Primary Open Angle Glaucoma: A Pilot Study.

OBJECTIVE

The purpose of this work was to study the safety of photobiomodulation therapy in patients with primary open angle glaucoma (POAG).

BACKGROUND DATA: Therapeutic options for POAG focus on lowering the intraocular pressure (IOP) but cannot stop disease progression to irreversible damages.

METHODS

The study was designed as a controlled, single-blinded, interventional case series (38 patients; 63 eyes). Low-level laser therapy was performed once or twice per week using a continuous wave (CW) diode laser (780 nm; 10 mW; 292 Hz modulation; 3 mm(2) beam spot). The limbus area was circularly irradiated for 30 sec (0.3 W/cm(2); 10 J/cm(2)) at a 1 cm distance. Additional parts of the bulbus were irradiated for 90 sec (30 J/cm(2)) pointing the beam toward retinal areas corresponding to defective visual fields. A control group of 10 patients (20 eyes) received mock treatment. Visual acuity was assessed using Snellen projection optotypes. IOP was determined by applanation tonometry. Visual fields were determined by kinetic Goldmann perimetry. Multifocal visual evoked potential (M-VEP) was recorded in 15 patients (30 eyes).

RESULTS

Poor visual acuity (≤ 20/25), initially found in 24 of 63 eyes (38.1%), improved in 17 (70.8%) eyes and did not change in 7 eyes (29.2%). Mean IOP dropped from 24.9 ± 14.9 to 15.0 ± 6.5 mm Hg (-39.7%, p < 0.001). Visual fields were either fully restored, improved by at least 10 degrees, or remained unchanged in 32, 29, and 2 of 63 eyes (51%, 46%, and 3%), respectively. Mean M-VEP latency was reduced by 13.5 msec (-8%, p < 0.001); mean amplitude increased by +677 nV (+14%, p < 0.001). Adverse effects were not observed. No changes were noted in control eyes.

CONCLUSIONS

This first small series of cases indicated that photobiomodulation might be a safe approach to lower IOP and to improve visual acuity and fields in eyes with POAG.