[Computer-assisted determination of indications and follow-up in strabismus surgery]

Two different program systems can be used when planning squint surgery. In the first system's algorithms (Robinson-Miller-Simonsz) are modelled the mechanical and innervational laws that govern eye movements (ophthalmotrope program). With ocular deviations and surgical procedures as input the program estimates postoperative deviations. The second program (Rüssmann-Konen) mimics any surgeon's planning of squint surgery using a defined decision tree and an appropriate number of mm-degree-relations (planning program). If ocular deviations, axial length, monocular excursions, and head posture are input the program proposes a surgical procedure. I combined both programs to enable the ophthalmotrope program to evaluate the propositions of the planning program.

I translated Simonsz' version 1/1989 of Robinson's program from FORTRAN to the programming language of my planning program (Turbo BASIC for IBM-PC) and connected both, the former becoming a module of the latter. Thus data entered into the planning program as well as the surgical procedure proposed may be immediately processed by the ophthalmotrope program to compute the presumed postoperative result. Several program loops allow a wide variation of data and procedures in successive program runs. Turbo BASIC being somewhat slower than FORTRAN quick computers (INTEL 80486, Pentium) are necessary lest processing lasts more than 1 minute.

A concomitant esotropia of 20 degrees and a head posture with elevation of the chin of 20 degrees are used to illustrate program properties. In the first case the planning program proposes a reasonable recess-resect-procedure 6 mm each, which is estimated to give a very slight overcorrection by the ophthalmotrope module. In the second case the planning module proposes a gaze shift procedure (Kestenbaum) on the vertical recti, which--in good agreement with my own experience--is estimated to produce an A-phenomenon of 19 degrees with an incyclotropia up to 30 degrees by the ophthalmotrope module. If an anterior margin recession of the superior oblique and an anterior margin tuck of the inferior oblique are added to the gaze shift procedure in both eyes neither any phenomenon nor any significant deviation are predicted by the ophthalmotrope module.

The combination of a planning module with an ophthalmotrope module in one program considerably enhances the usefulness of both.