Agreement and Reproducibility of Tono-pen®®®®® XL Tip Covered with Ocufilm and Fingertip of Surgical Glove in Intra-ocular Pressure Measurement
Niphon Sayawat MD*, Duangdao Duangnumsawang MD*
Affiliation : *Department of Ophthalmology, Khon Kaen University, Khon Kaen, Thailand
Objective : To compare the effect of using the fingertip of a surgical glove over Ocufilm® (Reichert Technologies, NY, USA) on
the agreement and reproducibility of measuring intra-ocular pressure (IOP) by the Tono-Pen® XL (Reichert Technologies, NY,
USA).
Study design : Experimental, clinical study.
Material and Method: Patients were randomized into two groups to receive IOP measurements using Tono-Pen® XL with
two different types of tip covers. In Group 1, the IOP of the right eyes were first measured using Ocufilm® as the tip cover,
followed by using the fingertip of a surgical glove. As for the left eyes, the tip of the surgical glove was used first, followed by
use of Ocufilm®. In Group 2, the IOP of the right eyes was first measured using the tip of the surgical glove, followed by use
of Ocufilm®, while for the left eye the latter was used first, followed by the tip of the surgical glove. A single operator measured
the IOP in each eye twice using each type of tip cover. Agreement between the Tono-Pen® XL measurements using the two
different tip covers was analyzed using the Bland-Altman analysis. The difference between the repeated measures was
assessed for reproducibility of the Tono-Pen® XL measurements with regard to each type of tip covers.
Results : 100 patients (200 eyes) were recruited into the present study. The mean difference of IOP taken by the Tono-Pen® XL
covered with Ocufilm® and the fingertip of a surgical glove was -0.21 mmHg (95%CI: -0.36 to -0.05). The limits of agreement
(confidence interval 95%) as calculated by the Bland-Altman plots for Ocufilm-Fingertip of a surgical glove was -2.43 to
+2.02 mmHg. The coefficient of repeatability of the Ocufilm® vs. the surgical glove was nearly the same (1.74 vs. 2.37,
respectively).
Conclusion : A significant agreement exists between using Ocufilm® and the fingertip of a surgical glove to cover the tip of a
Tono-Pen® XL for measuring IOP. The coefficient of repeatability was comparable between the two different types of tip covers.
When measuring IOP, the tip of a Tono-Pen® XL could therefore be covered by either Ocufilm® or the fingertip of a surgical
glove without compromising accuracy.
Keywords : Intra-ocular pressure, IOL, Tono-Pen® XL, Ocufilm®, Surgical glove, Agreement, Reproducibility
