An optical system which permits observation and coagulation of the retina through the Goldmann three-mirror contact glass is described. A compact unit is presented which is mounted on a Haag-Streit slit lamp table and can be attached to the Meyer-Schwickerath photocoagulator, although in principle, adaptation to other energy sources, lasers included, is possible.
An annular lens, which is part of the observation telescope collects the rays emerging from the iris thus bringing the retina and iris simultaneously into focus.
The advantages of the new system are: (a) the contact glass corrects for a large part of the aberrations of the dioptrical apparatus of the eye and (b) the energy source can be imaged equally well in the center and in the periphery of the retina. This results in high image quality of the image observed and high energy density of the area to be coagulated.
Fankhauser F, Lotmar W. Photocoagulation Through the Goldmann Contact Glass. Arch Ophthalmol. 1967;77(3):320-330. doi:10.1001/archopht.1967.00980020322006