Intraocular Pressure Evaluation after Myopic Refractive Surgery: A Comparison of Methods in 121 Eyes

Abstract

Purpose: To compare nine different formulas, developed to overcome the underestimation of intraocular pressure (IOP) readings after myopic photorefractive keratectomy (PRK).

Methods: The correlations between the modified IOP and the preoperative ones in 121 eyes of 72 patients who underwent myopic PRK were evaluated.

Results: The correlation and percentage of eyes in the range of ±2 mmHg were: Emara (R(2) = 0.1686, 74%), Munger (R(2) = 0.1665, 71%), Rosa (R(2) = 0.2489, 82%), Rashad (R(2) = 0.8593, 47%), Duch (R(2) = 0.1631, 82%), Arimoto (R(2) = 0.1638, 77%), Chihara (R(2) = 0.5389, 80%), Svedberg (R(2) = 0.1269, 54%), Kohlhaas (R(2) = 0.1074, 77%). In the case of known preoperative IOP, combining Rashad and Chihara's formulas (R(2) = 0.7730, 97%) were obtained. In the case of unknown preoperative IOP, combining Rosa and Duch's formulas (R(2) = 0.2484, 84%) were obtained.

Conclusion: Our results suggest calculating IOP with the average of Rashad and Chihara's formulas if the preoperative IOP is known and the average of Rosa and Duch's formulas if it is unknown.

Keywords: Corneal thickness; Goldmann applanation tonometry; glaucoma; myopia; photorefractive keratectomy.