Russell G E, Bergmanson J P, Barbeito R, Cross W D
University of Houston, College of Optometry, Tex. 77004.
Refract Corneal Surg. 1992 Jul-Aug;8(4):290-5.
In patients who are free of pathology, automatic refractions have shown close agreement with the subjective refractions. Clinical experience indicated that the normally strong relationship between objective and subjective refraction is significantly weakened as a result of radial keratotomy.
Seventy-two patients were refracted before and after surgery, objectively with a Humphrey Model #510 autorefractor and subjectively using a binocular refraction procedure without cycloplegia. All patients were free of ocular disease and had preoperative myopia ranging from -1.00 to -9.00 diopters as determined by the subjective spherical equivalent.
The results indicated that the preoperative difference between the mean spherical automatic and subjective refractions was a clinically acceptable 0.25 diopter. However, postoperatively, there was a statistically significant difference of 1.25 D with the automatic refractor determining more myopic refractions. Subsequent analysis revealed that the age of the patient had a direct bearing on this finding with patients less than 40 years of age showing more minus in the automatic refraction than patients 40 years and older.
The postoperative discrepancy between the two refractions may be explained by induced optical aberrations and may contribute towards the visual fluctuations experienced by radial keratotomy patients. It is postulated that the inconsistency in refractive determination is due to optical distortion since the age dependence of this effect may be related to the reduction of pupil size that occurs with aging. In the radial keratotomy patient, the practitioner is faced with a more complex and uncertain refraction that may vary according to refractive procedures used and other factors such as pupil size.
在无眼部病变的患者中，自动验光结果与主观验光结果显示出高度一致性。临床经验表明，由于放射状角膜切开术，客观验光与主观验光之间通常较强的关系会显著减弱。
72例患者在手术前后分别进行验光，客观验光使用Humphrey Model #510自动验光仪，主观验光采用无睫状肌麻痹的双眼验光程序。所有患者均无眼部疾病，根据主观等效球镜度测定，术前近视度数范围为-1.00至-9.00屈光度。
结果表明，术前平均球镜自动验光与主观验光之间的差异为临床上可接受的0.25屈光度。然而，术后自动验光仪测得的近视度数更高，两者之间存在1.25 D的统计学显著差异。后续分析显示，患者年龄对这一结果有直接影响，40岁以下患者的自动验光结果比40岁及以上患者更负。
两种验光结果术后的差异可能由诱导性光学像差解释，这可能是放射状角膜切开术患者出现视力波动的原因之一。据推测，屈光测定的不一致是由于光学畸变，因为这种效应的年龄依赖性可能与随着年龄增长瞳孔大小的减小有关。对于放射状角膜切开术患者，从业者面临着更复杂和不确定的验光情况，这可能因所使用的屈光程序和其他因素（如瞳孔大小）而异。
