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E Chihara; Corneal Topographic Parameters to Correct IOP Reading After LASIK . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3415.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To study topographic changes of the cornea in post-LASIK eyes and estimate pre-LASIK IOP reading. Methods: Goldmann applanation tonometric and air puff tonometric IOP, age, gender, tear film break up time, Shirmer I test, density of the corneal endothelium, spherical equivalent refractive error, central (CCT) and peripheral corneal thickness, corneal curvature (CC) within a central 3mm circle (CC3mm) and 5mm circle (CC5mm) were studied before and 1 week, 1 month and 3 months after LASIK in 58 Japanese eyes. Orbscan and Excimer laser apparatus EC5000 were a supply of Canon (Tokyo) and Nidek (Aichi, Japan). Results: After the LASIK (ablation 55.8 ± 22.8um) the CCT, CC, spherical equivalent refractive error regressed slightly, leaving the air puff tonometric IOP constant. During the follow up period for up to 3 months, difference between pre- and post LASIK IOP (Δ; IOP) at 1 week, and 1 month had poor correlationships with ablated corneal thickness, changes in the CCT, and CC. However, the Δ; applanation IOP at 3 months recovers statistically significant correlation with ablated thickness of the cornea (P=0.014), and also with a difference in the CC between 3mm and 5mm zone (P=0.027), thus allowing correction of the post LASIK IOP reading. By multiple regression analysis, an equation to correct post LASIK IOP was Δ; IOP=7.25 -1.04*( CC5mm-CC3mm)-0.0215*ablation, (P=0.00098). Our finding suggest that relationships between the corneal topography and post LASIK IOP reading changes with time. Other than the corneal topography, tissue changes by the wound healing processes may also affect IOP reading. P value between parameters (Pearson's correlation coefficient) View OriginalDownload SlideView OriginalDownload Slide Nappl.: air puff tonometric data, Appl. applanation tonometric data. Conclusion: Correlations between the delta IOP and corneal topographic changes are weak at 1 week and 1 month after the LASIK, but recover significant correlations at 3 months.
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