Accuracy and predictability of the compensatory function of Orbscan II in intraocular pressure measurements after laser in situ keratomileusis

Purpose. To evaluate the usefulness of the compensatory function of Orbscan II (Orbtak, Bausch & Lomb) for measuring postoperative intraoperative pressure (IOP) in laser in situ keratomileusis (LASIK) patients. Setting: Department of Ophthalmology, IIsan Pak Hospital, Inje University, IIsan, Korea. Methods; Two hundred ten patients had LASIK using the Hansatome(R) microkeratome (Bausch & Lomb) and the MEL 70 G-scan laser (Aesclepion-Meditec) and were examined retrospectively. The patients included in the study were divided into 2 groups: Group 1, 123 eyes with less than -6.0 diopters (D) of myopia; Group 2, 60 eyes with more than -6.0 D of myopia. The IOP was measured preoperatively and 2 and 4 weeks after LASIK using a noncontact tonometer (NCT CT-60, Topcon). The results were corrected with the Orbscan 11 program. Results: The mean IOPs in Group 1 were 16.35 mm Hg +/- 2.90 (SD) preoperatively, 10.80 +/- 2.21 mm Hg at 2 weeks, and 10.63 +/- 2.28 mm Hg at 4 weeks. After compensation with Orbscan 11, the 2-week and 4-week values were 16.81 +/- 3.14 mm Hg and 16.68 +/- 3.22 mm Hg, respectively, The mean IOPs in Group 2 were 17.63 +/- 2.93 mm Hg, 10.07 +/- 1.55 mm Hg, and 10.43 +/- 1.84 mm Hg, respectively; after compensation, they were 18.40 +/- 4.09 mm Hg and 18.05 +/- 4.09 mm Hg, respectively. After compensation with Orbscan 11, there were no statistically significant differences between the preoperative and postoperative IOPs. Conclusions: Orbscan II may help predict actual IOP values after LASIK and avoid the misinterpretation of high IOPs as normal IOPs, J Cataract Refract Surg 2002; 28: 259-264 (C) 2002 ASCRS and ESCRS.