A Study on “Photostimulative Effect” of Soft Laser

Histological Study of Rat Retina Damaged by Soft Laser Irradiation

Abstract

A laser as stimulated optical radiation was first described by Maiman in 1960, and since that time the application of the laser in dental and medical clinics has extended from diagnosis to treatment. On the other hand, a potential danger exists if an error is made during the irradiation procedure. However, the extent of retinal damage after exposure to a soft laser is still far from clear.
For demonstration of damage due to laser irradiation, ophthalmoscopic and light and electron microscopic studies were made on the hooded (pigmented) rat retina after the irradiation at therapeutic (peak power 20W) and experimental (peak power 80W) levels with a Ga-Al-As diode pulse laser (904nm) apparatus. And the features observed were compared with the retinal damage induced by argon laser photocoagulation (20mW for 0.02 sec and spot size of 50μm was used).
The following results were obtained.
1. In ophthalmoscopic observation, exposure of the retina to soft laser irradiation did not reveal any problems such as retinal damage and degeneration which were seen after photocoagulation.
2. Light and electron microscopical examination did not indicate any pathological changes in the retina throughout the observaion period, except for distention of choroidal vessels by 24 hours after the exposure at the experimental level.