Laser ophthalmoscope and coherent light.

SINCE the advent of laser sources producing coherent light, that is plane polarized and emitted as an almost parallel beam, there has been much conjecture about its use in ophthalmological practice. The human eye, with its clear media capable of refracting a parallel beam to image on the retina, appeared to be the logical target for such a unique source. The tissue reaction consequent to the retinal image of a laser source made it certain that its place as a phototherapeutic source would be investigated in relation to choroido-retinal pathology. Our original aim was to produce a convenient ophthalmoscopic laser device which would be more convenient to manipulate than the existing xenon lamp source (Ingram, 1964). Other features which encouraged the development of such an instrument were the ability to undertake treatment without the use of topical or retrobulbar anaesthesia and the resultant definitive choroido-retinal lesions reducing the area of damage and the risk of secondary sequelae such as vitreous involvement with vitreous traction band formation. Not least among our considerations was the desire to make a moderately-priced instrument widely available, so avoiding the invidious practice of having to refer patients to a few centres fortunate enough to possess a light coagulator.