A diagnostic ruler for strabismus and amblyopia.

We designed a diagnostic slide ruler for easier detection of strabismus and amblyopia, both of which begin in childhood. This new instrument makes the Parks three-step test easier to use and faster than other methods in diagnosing isolated cyclovertical muscle paralysis. Furthermore, the slide ruler tests visual acuity with both series letters and single letters. Incorporated into the instrument are Laurence's strabismometer, Haab's pupillometer, occluder, pinhole, and millimeter ruler. A laboratory model is now available, and this slide ruler can assist the ophthalmological practitioner in analyzing three-step test data more rapidly than graphs and computer programs can. This instrument can also diagnose pediatric patients in the early stages of microstrabismus and amblyopia to obtain the best therapeutic results.