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Correlation between automated and subjective refraction before and after photorefractive keratectomy
Nicola Rosa1, Attilio Iura, Mary Romano
1Eye Department, 2nd University of Naples, Italy. nicrosa@tin.it
Purpose:
To ascertain whether autorefractometry after photorefractive keratectomy (PRK) provides results that are comparable with subjective refractometry.
Methods:
The refractions of 159 eyes before and 1 month after PRK were determined with both automated and subjective refractometry, and the results of the two methods were compared.
Results:
Before PRK, subjective spherical equivalent refraction ranged from -15.25 to +0.25 D (mean -5.30 +/- 2.64 D) and automated spherical equivalent refraction ranged from -16.13 to -0.50 D (mean -6.10 +/- 2.74 D), with good correlation (r2 = 0.965) between the two methods. One month after PRK, subjective spherical equivalent refraction ranged from -1.63 to +3.50 D (mean +0.98 +/- 0.78 D) and automated spherical equivalent refraction ranged from -2.50 to +3.00 D (mean +0.36 +/- 0.96 D) with poor correlation (r2 = 0.401).
Conclusion:
Autorefractometry is less reliable in eyes after PRK, and consequently software changes are recommended for overcoming this problem.