[Intraocular pressure difference in Goldmann applanation tonometry versus a transpalpebral tonometer TGDc-01"PRA" in glaucoma patients].
OBJECTIVE
The object of this study was to compare intraocular pressure measurements obtained with the TGDc-01"PRA", a new, transpalpebral indentation tonometer, with those from Goldmann applanation tonometry in normal and glaucomatous eyes.


METHODS
Forty healthy eyes and 185 eyes suffering from glaucoma were included in the study. For Goldmann tonometry three measurements and for the TGDc-01 ten measurements were performed in a random order. All participants were placed in an upright position for all measurements.


RESULTS
In both groups a systematic increase of intraocular pressure was found within the TGDc-01-measurements. Therefore, the first 3 measurements of each device were used for further statistical analysis. No learning curve could be demonstrated for the TGDc-01-measurement with normal eyes. Within the group of normal eyes the mean IOD obtained with the TGDc-01 was 1.84 mmHg lower than the mean IOD obtained with Goldmann tonometry (two-sided Student's t-test; P = 0.003). In the group of glaucomatous eyes, the mean intraocular pressure obtained with the Goldmann tonometry was 19.7 +/- 10.1 mmHg, with the TGDC-01 18.1 +/- 7.1 mmHg (coefficient of correlation r = 0.64, P < 0.001). The mean standard deviation of intraocular pressure measurements with Goldmann tonometry was 1.2 +/- 0.9 mmHg, with the TGDc-01 3.1 +/- 2.1 mmHg. TGDc-01-measurements overestimated intraocular pressure compared to Goldmann tonometry up to values of 16 mmHg and underestimated intraocular pressure at values over 16 mmHg. The difference increased by 5.5 mmHg per 10 mmHg Goldmann tonometry. The probability of success, defined as TGDc-01-recordings within +/- 3 mmHg of the Goldmann tonometry recordings, was less than 53 % between 5 and 20 mmHg and less than 30 % between 20 and 30 mmHg. Intraocular pressure (Goldmann tonometry) over 30 mmHg was always accompanied by TGDc-01-measurements lower than 3 mmHg.


CONCLUSIONS
In eyes with elevated intraocular pressure, the TGDc-01"PRA" significantly underestimated the intraocular pressure measurement when compared to the gold standard, Goldmann tonometry. At present, measurement of the intraocular pressure with the TGDc-01 should not be used for clinical management of patients with glaucoma.
Schlote
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Abteilung I, Augenklinik der Universität Tübingen. Torsten.Schlote@med.uni-tuebingen.de
Landenberger
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D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019544:Equipment Failure Analysis; D005260:Female; D005901:Glaucoma / Q000150:complications / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D008904:Miniaturization; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014065:Tonometry, Ocular / Q000295:instrumentation* / Q000379:methods*