MORE THAN THREE YEARS EXPERIENCE WITH ELECTRONIC INTRAOCULAR NEEDLE TONOMETRY
W. Marx, F. Madjlessi, T. Reinhard, C. Althaus, R. Krallmann, R. Sundmacher
Background: In eyes with irregular corneae, e.g. after keratoplasty, suture tension, dystrophy, scarring or edema, applanation tonometry is often not performable or at least its results have to be doubted. For this reason we developed a new procedure of electronic intraocular needle tonometry which we have performed for more than three years in all eyes with irregular corneae and suspicion of glaucoma to control and if necessary correct applanation tonometry values. Patients and Methods: In topical anesthesia a special needle is introduced into the anterior chamber in order to measure intraocular pressure electronically. We have performed needle tonometry 330 times in 215 eyes with irregular corneae and suspicion of glaucoma after having calibrated the system with normal eyes.
Results: 1. Electronic intaocular needle tonometry allows to measure the true intraocular pressure and therefore is superior to applanation tonometry especially in irregular corneae. 2. In eyes with irregular corneae, applanation tonometry values are lower and often much lower than the true needle tonometry values. 3. Electronic intaocular needle tonometry allows to determine a correction factor for applanation tonometry if corneal irregularity is permanent and stable. 4.Complications have not been observed yet.
Heinrich-Heine-University, Eye Clinic, Moorenstr. 5, 40225 Düsseldorf