Clinical comparison of the Oculab Tono-Pen to the Goldmann applanation tonometer.
The Oculab Tono-Pen tonometer was compared with the Goldmann applanation tonometer through studies on 197 eyes of 103 patients with glaucoma or ocular hypertension to evaluate the reliability of the Tono-Pen in determining intraocular pressure (IOP). Patients were randomized into four groups and all applanations were done by the same investigator. The Tono-Pen initially used (Tono-Pen #1) failed to calibrate after being used on 77 eyes. Tono-Pen #2 was then obtained and tested. Each Tono-Pen showed high correlation with the Goldmann readings (r greater than or equal to 0.86 in both eyes). The overall sensitivity of the Tono-Pen in detecting IOPs of 21 mmHg or higher (as measured by the Goldmann instrument) was 62.1% in right eyes, 72.4% in left eyes, with corresponding specificities of 92.6% in the right and 97.1% in the left. Given the substantial increase in sensitivity noted with Tono-Pen #2, the Tono-Pen appears adequate for screening programs where an IOP of 21 mmHg or above is considered abnormal; however, at higher IOPs (greater than or equal to 30 mmHg) the Tono-Pens tended to underestimate Goldmann IOPs. At low IOPs (less than or equal to 9 mmHg) the Tono-Pens tended to overestimate the IOPs. Perhaps with further modifications of the instrument, it could be used for clinical diagnosis and management of glaucoma patients.
Department of Ophthalmology, University of Michigan, Ann Arbor 48105.
S F
SF
Kao
P R
PR
Lichter
T J
TJ
Bergstrom
S
S
Rowe
D C
DC
Musch
D000704:Analysis of Variance; D005069:Evaluation Studies as Topic; D006801:Humans; D007429:Intraocular Pressure; D013997:Time Factors; D014065:Tonometry, Ocular / Q000295:instrumentation* / Q000592:standards