[Clinical discrepancy between Schiötz and Perkins Tonometry in juvenile glaucoma]

Abstract

Background: In infantile glaucoma Schiotz and Perkins tonometry are often divergent. However, empirical data about the quantitative relation of Schiotz' and Perkins' measurements are lacking for this group of patients.

Patients and methods: 363 comparative IOP measurements by applanantion and indentation tonometry under general anesthesia were performed in 51 children (0-10 years) with infantile glaucoma during 01/01/88 and 30/06/95 at the University Eye Clinic Cologne.

Results: Correlation coefficient of both methods was 0.75 (p < 0.001). Schiotz tonometry surmounted Perkins tonometry in 78.8% of measurements. Differences of Schiotz and Perkins IOP measurements showed a normal distribution with mean value 4.37 +/- 5.8 mm Hg. Discrepancy between both methods increased significantly (p < 0.001) in eyes with corneal opacities (5.29 +/-6.35 mm Hg) compared with clear cornea (3.40 +/- 4.98 mm Hg). Discrepancy of Schiotz-Perkins tonometry was not influenced by axial length of the eye, corneal diameter and age of the patient.

Discussion: Marked discrepancy of applanation and indentation tonometry in infantile glaucoma is frequent. Decision for surgery should not base on tonometry alone, but on evaluation of additional clinical criteria like optic disc cup, corneal morphology and individual anamnesis.