Ultrasonographic assessment of the implant lens required to produce emmetropia after implantation.

Present-day implant lenses are esssentially thick lens systems. The usual methods by which the required power is assessed involve treating them as thin lens systems, thus giving rise to error. It is possible to avoid such an error by changing the approach to the problem. No attempt need be made to calculate the equivalent power of the implant lens required to produce emmetropia after implantation. The alternative, presented in this report, is to ascribe arbitrarily chosen parameters to the implant lens, thus reducing the calculation to the assessment of the back surface power required to focus light onto the retina.