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First Author: A.Kopylov RUSSIA
Co Author(s): V. Machekhin
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To conduct a comparative analysis of intraocular pressure (IOP), corneal curvature and thickness in myopic patients before and after LASIK surgery.
The Academician S.N. Fyodorov FSBI IRTC Eye Microsurgery Tambov branch, Tambov, Russia
32 eyes of 16 patients with myopia from 2.5 to 8.5 D were examined before and after LASIK surgery. There were 3 men and 13 women, aged from 18 to 24 years old. Besides the routine eye examination all patients before surgery and 1.5-2 months postoperatively underwent pachymetry with the measurements of radius of corneal curvature and corneal thickness, the Reichert 7 cr pneumotonometry, the applanation tonometry by Maklakov with P0 re-calculation by means of Nesterov-Egorovs measuring scales.
Directly after surgery and 1.5-2 months postoperatively visual acuity without correction in all patients equaled visual acuity with maximum correction before surgery and was 0.9-0.1. Clinical refraction reduced on the average of 5.0 D, corneal refraction of 4.0 D (from 44.08 to 40.19 D). The increase in radius of corneal curvature was statistically valid (from 7.67 to 8.45 mm). Corneal thickness reduced (from 539 to 435 microns) as well as the values of corneal compensated IOP and true Goldmann-correlated IOP (IOPg). The only invariable value was the value of true IOP (P0), measured by means of Nesterov-Egorovs scale during 10 g Maklakovs applanation tonometry. We have analyzed the correlative dependence between IOP level, corneal curvature and thickness. Before surgery no IOP dependence upon corneal thickness was noted (P>0.05), but postoperatively a positive correlation was observed only for IOPg (0.37). As regards corneal curvature its correlation with different methods of IOP measurements was observed before surgery, but statistical validity increased significantly after surgery.
We believe that IOP reduction after LASIK surgery is not true, but is a result of the change of corneal configuration, associated with its flattening. IOPg dependence on the corneal thickness seems to be connected with specificity of the method of measurement.