Rapid pneumatic and Mackay-Marg applanation tonometry

Glaucoma is usually considered to be adequately controlled when Goldmann applanation readings are below 22 mmHg. It is, however, now known that the intraocular pressure increases to a varying degree when the patient changes his posture from sitting to a recumbent position (Galin, McIvor, and Magruder, I963; Roberts and Rogers, I964; Hetland-Eriksen, Ig66a; Inglima, I966; Tarkkanen and Leikola, I967; Langham and McCarthy, I968; Anderson and Grant, 1973). Hetland-Eriksen (I966a, b) stated that the increase in intraocular pressure when in a recumbent position is in some way directly proportional to the initial intraocular pressure; this complicates our dependence on Goldmann tonometry as that procedure is performed routinely only in the sitting position. The present study, as well as making a clinical evaluation of the Mackay-Marg tonometer and the pneumatonograph, assesses the relationship of various postures to intraocular pressure in normal and glaucomatous eyes. The study was conducted using two of the more modem rapid applanation tonometers: the pneumatonograph (PTG)* and the Mackay-Marg electric tonometert as both are easily portable and continuously monitor the pressure on graph paper, and in addition, they can be used in any posture with equal ease and precision. Neither do they require the magnification or illumination of a slit-lamp nor the use of fluorescein, -as is essential in Goldmann tonometry. The pneumatonograph (Jain and Marmion, I976) and the Mackay-Marg (Kaufman, Wind, and Waltman, 1970) can be used to record exact pressures in cases of ectatic corneas or postkeratoplasty (Irvine and Kaufman, I969) as it is not imperative to apply the tip of the probe to the centre of the cornea in either procedure. The correlation of the PTG (Jain and Marmion,