[Results of clinical studies on drug modification of progressive lens opacities].
This paper begins with a discussion and explanation of the special features and requirements of a controlled clinical trial of the efficacy of anticataract preparations. So far, such trials have been carried out with Phakan and two types of eye drops (preparations "A" and "B") in accordance with the conditions for controlled therapy studies. The procedure is explained taking the Phakan study as an example. Lens findings were evaluated by densitometric image analysis of Scheimpflug photographs of the anterior eye segment, made at different times during the trial. The validity of the data for statistical calculations was at first overrated. Mean values obtained with the method, however, correspond to the values expected: they show the required progression over longer periods. The reliability of the method was checked by taking into account the clinical observations and visual acuity tests on 35 patients (62 eyes) which had been under observation for a considerable period of time (up to 5.5 years). The results indicate clearly that Phakan can favorably influence opacities located in the lens cortex and that after a 9-month treatment even a prolonged effect (2-3 years) may be observed. With preparation "A" some indication - although not completely satisfactory - of efficacy in cases of cortical opacities was found. A one-year treatment with preparation "B" produced no differences as compared to untreated controls. However, it appears advisable to extend observation periods in future trials.