importance of corneal thickness in applanation tonometry

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    Importance of corneal thickness in applanation tonometry


    N . Ehlers and T . Bramsen

    Department of Ophthalmology, h h u s Kommunehospital,

    Arhus. Danmark

    In several groups of non-glaucomatous patients a positive s ta t is t ical correlat ion was found between central corneal thickness and intraocular p r e s s u r e measured by applanation tonometry. Normal corneal thickness was found in glaucoma s im- plex, a thick cornea was found in ocular hypertension and a thin cornea in low- tension glaucoma.

    On the assumption that the thickness influences the measured value of the in- t raocular p r e s s u r e , as emphasized in the original papers of Goldmann, readings with the applanation tonometer were made a t various intraocular hydrostatic pres - s u r e s and compared with central corneal thickness. In human eyes with a normal corneal thickness tonometer readings and hydrostatic p r e s s u r e coincide, with thick corneas the readings were too high, with thin corneas too low. The correlat ion be- tween corneal thickness and the e r r o r of applanation tonometry ( A P ) was statisti- cally highly significant (p -=O .001) . A table h a s been calculated, showing the cor - rection to be added to the applanation reading a t the various corneal thickness-valuet The central corneal thickness is a parameter which should be taken into considera- tion when evaluating applanation tonometer readings.

    The A 0 - non contact tonometer BY

    P . Nelleman Sbrensen

    Department of Ophthalmology, Rigshospitalet, Copenhagen, Denmark

    The measurement of the intraocular pressure by a non contact tonometer was c o r - related to Goldmann tonometer in 20 normal persons , 20 glaucomatous patients and 8 patients suffering from corneal d i seases .

    persons to their skill of fixation and in the eye patients to height of p r e s s u r e and t o corneal state.

    The e r r o r in measurement for the non contact tonometer was related in normal