The evaluation of large series of cataract extractions is most feasible using a computer. We have computerized the details of 7503 cataract extractions (performed in the years 1961-1975). The analysis is based on a new computerreadable form. Its application is shown in two examples for comparing surgical results: 1. cataract extractions by forceps, suction cup or cryoprobe, the surgeon wearing magnifying-goggles; 2. cataract extractions by cryoprobe using the surgical microscope. The evaluation of results had been done separately for residents and experienced surgeons. RESULTS In experienced surgeons the percentage of uncomplicated extractions increased considerably with the cryoprobe (86.5%) as compared to 77% using the suction cup. The surgical microscope in that series have no significant increase of the success rate (cryoprobe 88.4%). Residents had more advantages from both technical aids: no microscope, suction cup: 73.5%, cryo: 82.5%, with microscope, cryo: 90.3%. Their results compare well with those of the experienced surgeons, since they are given straight-forward cases only and they operate under the strictest supervision of an experienced surgeon.