Objectives: To investigate, using multifocal electroretinogram (mfERG), the effect of electroacupuncture (EA) on retinal function in rats with experimental glaucoma.
Design and subjects: Glaucoma was induced in the right eyes of 15 adult female Sprague-Dawley rats by laser photocoagulation for three quarters of the perilimbal and episcleral vessels. The left eye of each rat was used as the control. The animals were divided into 3 groups: no treatment (non-EA control group), 2 Hz EA group, and 100 Hz EA group. EA treatment at different frequencies can produce different levels of analgesia and hence the effect of EA with different frequencies on glaucoma treatment was investigated. Both eyes of each rat in the EA experimental groups received 3 EA treatment sessions each week for 4 weeks. The retinal function was measured using mfERG after 4 weeks of EA treatment.
Results: There was no significant difference in the amplitude (both N1 trough and P1 peak) of mfERG firstorder kernel response between the treatment and control groups. In determining the waveform characteristics by the ratio of N1 amplitude to P1 amplitude (N/P ratio), obvious differences were found in the N/P ratio between the control eyes and the glaucoma eyes in the non-EA group and the 100 Hz EA treatment group, but similar values in the N/P ratio were observed between the control eyes and the glaucoma eyes in the 2 Hz EA treatment group. The waveform from the eyes with glaucoma was deformed in both the non-EA group and the 100 Hz EA group, but the waveform from the glaucomatous eye was preserved in the 2 Hz EA group.
Conclusions: Application of EA at 2 Hz provides neuroprotection by preserving retinal function in rats with experimental glaucoma. Low frequency EA may be an alternative therapy in the treatment of glaucoma.