[The Tono-Pen XL--a tonometer suitable for measurement of common and less common conditions associated with intraocular pressure].

: In the introduction the authors describe a portable electronic tonometer Tono-pen XL and explain the principle of its function. After this follows a comparative study with Goldmann's applanation tonometry (AT) on 240 eyes in children aged 7 to 18 years. The mean value of the intraocular pressure (IOP) was 17.09 torr +/- 4.35 SD with AT and 16.46 torr +/- 4.04 SD when using the Tono-pen. Regression analysis revealed a very close correlation between the two methods of assessment (r = 0.925) with a high statistical significance (p < 0.0005). The difference as compared with AT values was constant, on average close to -0.68 torr in the whole range from 7 to 35 torr. The authors found also a significantly greater variability of values obtained by means of the Tono-pen (p = 0.0009), the mean scatter of individual values being 1.55 torr as compared with 1.25 torr in AT. However 97.1% of the eyes were within a range of 3 torr. The authors did not find a significant relationship between assessment by means of the Tono-pen and the doctor's experience. The unique advantage of Tono-pen as compared with all other methods of routine tonometry is the relatively accurate assessment of the IOP under irregular conditions of the cornea. It is also possible to take measurements in children where AT cannot be used.