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Abstract #18978 Published in IGR 3-1
Intraocular pressure and photorefractive keratectomy: a comparison of three different tonometers
Garzozi HJ; Chung HS; Lang Y; Kagemann L; Harris ACornea 2001; 20: 33-36
PURPOSE: To evaluate the intraocular pressure (IOP) with three different instruments, Goldmann applanation tonometer (GAT), noncontact tonometer, and Tono-Pen after photorefractive keratectomy (PRK) for myopia. METHODS: A prospective case series study to evaluate preoperative and postoperative IOP measurements of 149 eyes at 12 months. The authors performed GAT, noncontact tonometry, Tono-Pen central, and Tono-Pen temporal periphery measurements. They also performed measurements of the central corneal thickness (CCT) by ultrasonic pachymetry and keratometry. Preoperative IOP reading served as control for all studies. RESULTS: After PRK, IOP reading was significantly reduced in the treated eyes when compared with the control measurements (11.87 ± 1.73 versus 13.37 ± 1.52 mmHg, p < 0.0001 with GAT; 12.07 ± 1.6 versus 13.51 ± 1.59 mmHg, p < 0.0001 with noncontact tonometer; 12.18 ± 1.6 versus 13.48 ± 1.55 mmHg, p < 0.0001 with Tono- Pen central; 13.48 ± 1.65 versus 13.71 ± 1.56 Hg, p < 0.0104 with Tono-Pen temporal periphery). There was also a significant correlation between IOP reading changes measured by GAT, noncontact tonometer, Tono-Pen central, and change of CCT and between reduction of IOP reading and keratometry (r2 > 0.39, p < 0.0001 for each). The correlation between IOP reading change by Tono-Pen temporal periphery and CCT was also significant but r2 value was only 0.034. Tono-Pen temporal periphery postoperative IOP measurements had the best correlation with preoperative GAT IOP (r2 = 0.57, p < 0.0001). CONCLUSIONS. PRK reduced IOP reading as measured by GAT, noncontact tonometer, and Tono-Pen central; less so when measured by Tono-Pen temporal periphery. Early detection of glaucoma and IOP follow-up in glaucoma patients may be done best by peripheral Tono-Pen measurements over the nonablated cornea.
Dr H.J. Garzozi, Department of Ophthalmology, Haemek Medical Centre, 18101 Afula, Israel
Classification:
6.1 Intraocular pressure measurement; factors affecting IOP (Part of: 6 Clinical examination methods)