CLINICAL UTILITY OF THE BARRETT KERATOSCOPE WITH ASTIGMATIC DIAL

Intraoperative keratometry allows some degree of control over corneal astigmatism during cataract surgery I describe the clinical use of the Barrett keratoscope combined with an astigmatic dial that quantifies the information obtained by this simple, inexpensive, hand-held surgic al keratometer. Based on a comparison of intraoperative measurements w ith those taken after extracapsular cataract surgery with an automated keratometer, I conclude that intraoperative keratometry reliably pred icted the postoperative astigmatism. For those who had the intraocular pressure (IOP) set between 15 and 20 mm Hg intraoperatively, the mean deviation of the first postoperative measurement from the intraoperat ive measurement of astigmatism was +/-1.03 D (standard error, 1.56 dio pters; 95% confidence interval 0.712 to 1.35 D). When the IOP was not set, the postoperative astigmatism differed from the intraoperative re ading by more than 2.00 D for 50% of the cases. Setting the IOP prior to intraoperative keratometry significantly improved the reliability o f the measurement. Intraoperative keratometry by the simple device use d in this study is of sufficient utility to allow the surgeon to adjus t for the predicted changes in the corneal astigmatism at the time of surgery.