Comparison of objective and subjective refraction before and after laser in situ keratomileusis

Purpose: To compare the accuracy and reliability of objective and subjectiv e refractions before and after laser in situ keratomileusis (LASIK) for myo pia, hyperopia, and astigmatism. Setting: Augenchirurgie und Laserzentrum Hochrum, innsbruck, Austria. Methods: in this prospective study, the objective refraction obtained with the Nidek AR-K 900 autorefractor was compared with the subjective refractio n in 159 eyes (125 with myopia and 34 with hyperopia) operated on with 2 di fferent lasers. Refractions were done before and 6 months after LASIK. Results: Preoperatively, the objective and subjective refractions correlate d better in eyes with low myopia than in those with high myopia (P <.01). P ostoperatively, objective refraction was less accurate and reliable than pr eoperatively. The difference between the objective and subjective spherical refractions was statistically significant (P <.0001) after LASIK in eyes w ith hyperopia. The correlation between the objective and subjective cylindr ical refractions was stronger preoperatively. Especially after LASIK for hy peropia, the objective refraction did not reliably assess the magnitude and axis of the cylinder. The preoperative refractive error did not significan tly affect the preoperative and postoperative difference between the object ive and subjective refractions or the change between the preoperative and p ostoperative mean differences. The type of excimer laser used significantly affected the difference between the Objective and subjective refractions. Conclusions: Especially after LASIK for hyperopia, the objective refraction determined with the Nidek AR-K 900 autorefractor delivered erroneous resul ts, which have implications for postoperative care and preoperative measure ments for ocular surgery such as enhancement procedures or cataract surgery . J Cataract Refract Surg 1999; 25: 827-835 (C) 1999 ASCRS and ESCRS.