A Comparative Study of Intraocular Pressure Measurements by Goldmann Applanation Tonometer and Schiotztonometer and the Study of Schiotz Tonometer a Screening Tool in North Karnataka Population
Keywords:Goldmannapplanation tonometer, Schiotz indentation tonometer; screening tool, Intra Ocular pressure (IOP)
Background: Glaucoma is a multifactorial disease with common end point characteristics affecting the optic nerve.
It is defined as an optic neuropathy characterised by specific structural findings in the optic disc (increased Vertical
Cup Disc Ratio (VCDR) or VCDR asymmetry >97.5 percentile) and particular functional deficits in automated
visual field testing. It consists of three components: the optic nerve head, the visualfield, and intraocular pressure.
Detecting the intraocular pressure is essential in not only initiating treatment, but also in monitoring the response
Method: 210 purposively selected patients were subjected to three methods of tonometry – Goldmannapplanation
tonometry, Schiotz indentation tonometry (with the 5.5g, 7.5g and 10 g weights). Three recordings were obtained
with each method and the arithmetic mean taken as the intraocular pressure. The data was statistically analyzed
using the intra-class correlation coefficient. Sensitivity and specificity were also calculated for the Schiotz tonometer.
Results: The Schiotz tonometer showed fair agreement with the Gold mannapplanationtonometer. The Schiotz
tonometer scored low as an effective screening tool.
Conclusion: The current study shows that the Schiotz tonometer compares favourably with the
Goldmannapplanation tonometer showing fair agreement with it. It showed good specificity and was reliable in
detection of positives, excluding false positives.
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