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June 1988

Comparison of the Tono-Pen to the Goldmann Applanation Tonometer

Author Affiliations

From the Kresge Eye Institute, Wayne State University School of Medicine, Detroit. Dr Frenkel is now with the Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston.

Arch Ophthalmol. 1988;106(6):750-753. doi:10.1001/archopht.1988.01060130820030

• Oculab Tono-Pen tonometry was compared with Goldmann applanation tonometry in 142 eyes of 71 patients without corneal problems. Overall we found 63% of the Tono-Pen readings to be within ±2 mm Hg of the Goldmann applanation tonometry readings and 77% to be within ±3 mm Hg, while 4% were within at least ±7 mm Hg difference. The correlation coefficient between the readings of the two instruments was.84. The mean value of the paired differences was 0.81 ± 3.09 mm Hg overall, −1.78 ± 1.86 mm Hg in the 4 to 10 mm Hg interval, 0.07 ± 2.97 mm Hg in the 11 to 20 mm Hg interval, 1.27 ± 2.62 mm Hg in the 21 to 30 mm Hg interval, and 4.15 ± 2.28 mm Hg in the 31 to 45 mm Hg interval. We conclude that the Tono-Pen measures intraocular pressure in a manner that corresponds well to the Goldmann tonometer in the 11 to 20 mm Hg interval, and fairly well in the 4 to 10 mm Hg and 21 to 30 mm Hg intervals. It lacks good correspondence in the 31 to 45 mm Hg interval.

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