title: Bilateral recording of human intraocular pressure with an improved applanating suction cup tonograph.
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 between the applanating and the applanated 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 that attaches the cup to the cornea is - as in the previous model - 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 per min was: intraocular pressure = 0.9 X cup pressure -3 (mmHg), r = 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, and the method can be strongly recommended when accurate, bilateral pressure recordings are desired for periods up to one h in supine subjects. At intraocular pressures above 35 mmHg, the tonograph may underestimate the pressure under certain, unfavourable conditions.
mesh_terms: D014065:Tonometry, Ocular / Q000295:instrumentation* / Q000379:methods; D014160:Transducers, Pressure