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Ciro Tamburrelli, Agostino Salvatore Vaiano, Tommaso Salgarello, Carmela Grazia Caputo, Luigi Scullica; Tonometric Changes of Latanoprost-Induced Intraocular Pressure Reduction after Photorefractive Keratectomy. Invest. Ophthalmol. Vis. Sci. 2004;45(3):846-850. https://doi.org/10.1167/iovs.03-0625.
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© ARVO (1962-2015); The Authors (2016-present)
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 men and 12 women, mean age ± SD: 31.7 ± 6.2 years) who were 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 1 drop of 0.005% latanoprost, were performed before and 6 months after PRK. All measured IOPs were recalculated by a correction factor for CCT and R and expressed as true IOP (IOPT) measurements.
results. The 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. The mean IOP at baseline was 15.8 ± 2.92 and 12.23 ± 2.37 mm Hg, and after latanoprost administration was 12.54 ± 1.97 and 10.19 ± 1.47 mm Hg, before and after PRK, respectively. The mean IOPT at baseline was 15.46 ± 1.08 and 16.18 ± 2.31 mm Hg, and after latanoprost administration was 11.85 ± 1.56 and 12.96 ± 1.71 mm Hg, before and after PRK, respectively. The mean IOP and IOPT reductions after latanoprost administration were, respectively, 3.25 ± 1.66 and 3.61 ± 1.7 mm Hg before PRK, and 2.03 ± 1.42 and 3.22 ± 1.79 mm Hg after PRK. Pre- and postoperative IOP reduction significantly differed (P < 0.001), but not IOPT.
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 pharmacologic efficacy may be avoided if the measured IOP is corrected by a proper nomogram.
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