Effect of resisting tonometry on intraocular pressure

Children and patients with developmental delay frequently resist the procedure of tonometry. Intraocular pressure (IOP) readings, if obtained under stressful circumstances, may have questionable reliability because IOP is influenced by numerous factors characteristic of the uncooperative patient. These factors include possible increases in arterial blood pressure, intraocular vascular engorgement, and pressure on the globe. A study of the effect upon IOP of these factors occurring simultaneously has not been reported previously.

We measured IOP using the Tono-Pen on 40 cooperative adults under normal conditions and again under conditions simulating the resistant patient.

Paired t-test revealed a statistically significant difference between IOP readings under the two conditions (p < 0.001), with IOP under "resistant" conditions showing more variability and averaging 6mmHg higher than under normal conditions.

We conclude that IOP readings in resistant patients should be viewed with caution. The possibility of obtaining false high readings in these patients could lead to unnecessary glaucoma evaluations if based only on elevated IOP readings.