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Abstract #10339 Published in IGR 6-1
Tonometric changes of latanoprost-induced intraocular pressure reduction after photorefractive keratectomy
Tamburrelli C; Vaiano AS; Salgarello T; Caputo CG; Scullica LInvestigative Ophthalmology and Visual Science 2004; 45: 846-850
PURPOSE: To assess whether tonometric measurements of the drop in intraocular pressure (IOP) induced by 0.005% latanoprost are modified after photorefractive keratectomy (PRK). METHODS: Data from 24 randomly selected eyes of 24 patients (12 males and 12 females, mean age ± SD: 31.7 ± 6.2 years) undergoing bilateral PRK for myopia (-6.38 ± 2.26 D) were obtained. Objective refraction, central corneal thickness (CCT), anterior radius of corneal curvature (R), and IOP measurements at baseline and 24 hours after one drop of 0.005% latanoprost, were performed before and six months after PRK. All measured IOP was recalculated by a correction factor for CCT and R and expressed as true IOP (IOPT) measurements. RESULTS: Mean CCT ± SD was 544.58 ± 36.03 and 463.21 ± 38.59 μm, and the anterior radius of corneal curvature was 7.73 ± 0.26 and 8.33 ± 0.37 mm, before and after PRK, respectively. Mean IOP at baseline was 15.8 ± 2.92 and 12.23 ± 2.37 mmHg, and after latanoprost administration was 12.54 ± 1.97 and 10.19 ± 1.47 mmHg, before and after PRK, respectively. Mean IOPT at baseline was 15.46 ± 1.08 and 16.18 ± 2.31 mmHg, and after latanoprost administration 11.85 ± 1.56 and 12.96 ± 1.71 mmHg, before and after PRK, respectively. Mean IOP and IOPT reductions after latanoprost administration were 3.25 ± 1.66 and 3.61 ± 1.7 mmHg before PRK, and 2.03 ± 1.42 and 3.22 ± 1.79 mmHg after PRK, respectively. Pre- and postoperative IOP reduction significantly differed (p < 0.001), but IOPT did not. CONCLUSIONS: The effect of hypotensive drugs on IOP readings may be underestimated because of measurement errors due to CCT reduction and R increase after PRK for myopia. Misdiagnosis of reduced pharmacological efficacy may be avoided if the measured IOP is corrected by a proper nomogram.
Dr. C. Tamburrelli, Institute of Ophthalmology, Catholic University, Rome, Italy. citam@tiscalinet.it
Classification:
6.1 Intraocular pressure measurement; factors affecting IOP (Part of: 6 Clinical examination methods)
11.4 Prostaglandins (Part of: 11 Medical treatment)