Equivalent keratometer reading tool for biometric calculation in asymmetric corneas: case series

ABSTRACT The accuracy of the intraocular lens calculation is not perfect, and postoperative refractive errors are common, especially in patients who have undergone previous refractive surgery or in presence of asymmetric corneas. Corneal power after refractive surgery can be more accurately measured using the total optical power map in the 4-mm central zone, by means of Orbscan II or equivalent keratometric reading map available on pentacam, with central measurements of 1.0, 2.0, 3.0 and 4.5 mm. The purpose of this case series is to demonstrate four approaches performed in special corneal conditions, using pentacam equivalent keratometric reading to measure corneal power and biometrics, and comparing with possible results obtained with other strategies. The four eyes were submitted to previous refractive procedures, and the intraocular lens chosen from the use of the corneal power calculated by equivalent keratometric reading showed excellent postoperative results.

摘要 人工晶状体（intraocular lens）度数计算的准确性尚未达到完美，术后屈光不正颇为常见，尤其好发于既往接受过屈光手术或存在角膜不对称的患者。对于屈光手术后的角膜屈光力，采用4mm中央区的总光功率图可实现更精准的测量，具体可借助奥比斯坎II（Orbscan II）眼前节分析仪，或帕塔康（Pentacam）三维眼前节分析仪提供的等效角膜曲率读数图，其中央测量直径分别为1.0mm、2.0mm、3.0mm及4.5mm。本病例系列研究旨在展示四种针对特殊角膜状态的手术方案：通过帕塔康的等效角膜曲率读数计算角膜屈光力与眼部生物测量参数，并与其他测量策略可能获得的结果进行对比。本研究纳入的4只患眼均曾接受过屈光手术，基于该等效角膜曲率读数计算所得的角膜屈光力选择人工晶状体后，术后疗效优异。