FP-1453 Evaluation Of Schiotz, Perkins, Tono-pen In Paediatric Glaucomas Under General Anesthesia Dr. ANUP DAS Dr. Rajagopal Kunnatur Dr. R Ramakrishnan Aravind Eye Care System Tirunelveli
Introduction • Elevated intraocular pressure (IOP) is the most important risk factor for glaucoma and tonometry remains the cornerstone of both diagnosis and management. • Wilson MR. Epidemiological features of glaucoma. International ophthalmology clinics, 1990, 30(3):153–60. • There is little mean difference in IOP obtained by Schiøtz and applanationtonometry in population studies, the agreement between readings obtained by the 2 methods in individual eyes is far from satisfactory. • Armaly MF. Schiotztonometer calibration and applanationtonometry. Archives of ophthalmology, 1960, 64:426–32.
The Goldmanntonometer, however, cannot be used for bedridden patients, for younger children, in the operating room and in other situations outside the consulting room. • The Perkins tonometer (Clement-Clarke Inc., Columbus, Ohio, USA) is a portable Goldmannapplanationtonometer. However, it is not easy to use and not always suitable. • Wessels IF, Oh Y. Tonometer utilization, accuracy, and calibration under field conditions. Archives of ophthalmology, 1990, 108(12):1709–12.
Aim • To compare the results of Tono-Pen, Schiøtz and Perkins tonometers in paediatric Glaucomas under general anaesthesia & to analyse whether they could be used interchangeably to measure elevated IOP
Materials and Methods • Retrospective analysis of 119 eyes of 69 cases of congenital glaucoma who underwent EUA in past 5 yrs was carried out. • Cases where all 3 tonometers were used were included in the study. • The examinations were performed in the following order: • Perkins applanationtonometry (Clement-Clarke Inc., Columbus, OH, USA), • Tono-Pen XL tonometry (Mentor, Santa Barbara, CA, USA), • Schiøtz indentation tonometry.
Materials and Methods • Tono-Pen measurements were repeated at least 4 times for each eye and the average at P < 0.05 was recorded. • The Schiøtz reading was repeated using 5.5, 7.5 and 10.0 plungers for each subject. • The portable tonometers were compared with each other using 2-way analysis of variance. • 95% limits of agreement were calculated as ± 1.96 standard deviations (SD) of the differences.
Results • All tonometers gave significantly different measurements from each other.
Results • However, with a mean difference of 1.3 mmHg and 95% limits of agreement of –5.6 to +8.6mm hg, the greatest agreement was between the Perkins and Tono-Pen tonometers. • Schiotz readings had better agreement with tonopen than perkins +1.5 (p=0.017).
In thicker corneas schiotz showed innocuously high readings. • Above 33 mm of IOP, both tonopen & schiotz showed good correlation( mean diff. +0.2 to +2.7). • At all times perkins vs schiotz had little less agreement with MD +2.9mmHg (p=0.001)
Literature review • A similar study by Bordon et al found a good correlation between the Tono-Pen and Perkins tonometers (r = 0.867) and found no statistically significant difference between the mean difference of IOP values obtained with the Tono-Pen and Perkins (P > 0.05). • The Schiøtz measurements were significantly higher than those obtained with the Perkins and the Tono-Pen tonometers (P < 0.05). • Bordon AF, Katsumi O, Hirose T. Tonometry in pediatric patients: a comparative study among Tono-pen, Perkins, and Schiotztonometers. Journal of pediatric ophthalmology and strabismus, 1995, 32(6):373–7.
Conclusion • At all times tonopen & perkins had greatest agreement. • At high readings tonopen & schiotz showed good correlations and can be used interchangeably.