BILATERAL RECORDING OF HUMAN INTRAOCULAR PRESSURE WITH AN IMPROVED APPLANATING SUCTION CUP TONOGRAPH

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Abstract
An improved applanating suction cup for continuous recording of human intraocular pressure is described. The new cup adheres better, is easier to calibrate and is simpler to handle, mainly due to a different curvature of the applanating surface. The interspace btween the applanating and the applanted surface, in which the pressure is measured, is continuously flushed with saline from a flow system (Intraflo) connected to the dome of the pressure transducer. The suction attaching the cup to the cornea is provided by a saline-filled tube hanging from the cup. In 51 human cadaver eyes the calibration for static pressures and pressures oscillating up to 124 cycles/min was determined: intraocular pressure = 0.9 .times. cup pressure -3 (mmHg), r [correlation coefficient] = 0.995. The cup reduced ocular rigidity by 5% only and increased the intraocular pressure transiently by 4 mmHg when applied. Simultaneous bilateral recordings were obtained in 400 normo- or hypertensive eyes from 206 subjects. The cup was atraumatic. The method is strongly recommended when accurate, bilateral pressure recordings are desired for periods up to 1 h in supine subjects. At intraocular pressures above 35 mmHg, the tonograph may underestimate the pressure under certain unfavorable conditions.