Axial length in applanation tonometry.

PURPOSE

To investigate the clinical applicability of a physical principle that suggests that a large globe offers less resistance to applanation than a smaller one.

SETTING

Referral practice, Bridgeport, Connecticut, USA.

METHODS

The correlation between axial length and applanation tonometry in 513 adult eyes, arbitrarily chosen from a referral practice, was examined using regression analysis.

RESULTS

A statistically significant negative correlation was found; that is, for every 1.0 mm increase in axial length, the tonometry value was 0.29 units lower (P =.0002). In women, the mean axial length was 1.04 mm shorter and the mean intraocular pressure 0.54 mm Hg higher than in men.

CONCLUSIONS

Globe size influenced applanation tonometry readings. Hence, when the tonometry record does not fit the clinical findings, axial length measurement may help interpret its significance.