[An expert system for the diagnosis of intraocular pressure disorders].

PURPOSE

This expert system (ES) is designed to avoid the four types of diagnosis errors: by omission or by confusion both of which may occur when collecting signs and symptoms and when analyzed data. This ES uses a thesaurus containing 42 classical and objective signs and a comprehensive library. For a given case report, it provides the practitioner with a positive diagnosis, and if possible, one or several etiologies taking into account all the data known about intraocular disorders.

METHODS

This ES is run on a PC-compatible computer with 640 KB RAM and without hard drive. The 90 KB program is written in compiled Basic. After checking the case record to rule out nonsenses, the logic considers every sign of the case record as equivalent. Likewise, in the first stage all syndromes are considered of equal likelihood. The syndromic diagnosis is set by identification. Comparisons of prevalence interfere, when needed, in a second phase, within the framework of etiological diagnosis.

RESULTS

When tested on a set of 180 cases records combined with 115 cases extracted from the literature corresponding to more than 1,900 diaagnoses, this ES yielded 100% correct positive and differential diagnoses, thus validating the logial hypotheses. Probability of error by omission was less than a 3% and probability of error by confusion was well below 0.1%. Besides, the logical analysis shelds light on the intellectual mechanisms of diagnosis.

CONCLUSIONS

This ES is user-friendly, easy to update and can answer clinical problems the ophthalmologist has to cope with in diagnosis and therapy of intraocular pressure disorders.