This thesis has developed and evaluated a novel calibration procedure for an eye tracker. The development phase has included programming and integration with the existing application programming interfaces. The evaluation phase included reliability and validity testing, as well as statistical analysis in terms of repeatability, objectivity, comprehension, relevance, and independence of the performance of the Tobii T60/T120 Eye Tracker on healthy subjects. The experimental results have shown that the prototype application gives the expected benefits in a clinical setting. A conclusion of this thesis is that eye tracking technology could be an improvement over existing methods for screening of eye alignment and diagnostics of ophthalmic disorders, such as strabismus (crossed eyes) or amblyopia (lazy eye). However, applying this technology to clinical cases will require further development. This development is suggested as future work.