[Gernet and GOW-70-Program intraocular lens calculation. Significance of the of the position of the principal plane of the lens in phakic and pseudophakic eyes for accuracy of the target refraction of different IOL types].

The GOW 70 PC programme utilises the individual bio-anatomy of the phacic cataract eye in the IOL power calculation for multifocal or monofocal in-the-bag-implantation for all common IOL types. In addition, an aniseiconia evaluation programme is included. The Gernet IOL power calculation is based on the GOW 70, 71 formulae which consists of the PC programme (one disc), one table (the 60% rule), an instruction for use in personal computers (Windows, Word) and in the 60% procedure. This is based on ultrasound immersion measurements of about 20,000 phacic eyes with and without cataracts and after 2,000 IOL implantations by various surgeons using the d-values of the human eye lenses of the cataract eye and the d-values of the IOL types used. The d-value of a phacic eye is the distance between the corneal vertex and the principal plane (infinitely thin lenses) of the human eye lens and is formed from the depth of the anterior segment (cornea + AC) + 60% of the human lens thickness. The d-value of a pseudophacic eye is the distance between the corneal vertex and the principal plane of the chosen IOL type. In 1984, the first definite clinical connection between the d-values of human eye lenses and of implanted PC IOL (6.0 mm-1.5 mm = 4.5 mm) was established. In 1992 and 1998 it was extended to the "newer" 60% rule and to the 60% procedure, respectively.