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. (C) 2002 ASCRS and ESCRS.

Mark, HH., Robbins, KP., & Mark, T. (2002). Axial length in applanation tonometry. Journal of Cataract and Refractive Surgery, 28(3), 504-506. [PII S0886-3350(01)01091-4].