NOV 11, 2013
This prospective study found that corneal hysteresis can help predict the final refractive result of cataract surgery.
The study included 40 patients (40 eyes) scheduled for cataract surgery. They underwent either coaxial small-incision cataract surgery (SICS) (2.75 mm width) or coaxial MICS (1.7 and 2.2 mm width) depending on the habits of one of two surgeons who performed each procedure.
The patients were assessed for surgically induced corneal astigmatism (SIA) and higher-order aberrations using a Scheimpflug rotating camera (Pentacam) together with corneal imaging by optical coherence tomography (Spectralis) and biomechanical analysis by the Ocular Response Analyzer preoperatively and 1, 7 and 30 days postoperatively.
The authors found that SIA and higher-order aberrations were significantly lower after microincision surgery (≤ 2.2 mm) than after small-incision surgery (2.75 mm) (both P < 0.01). Multivariate analysis showed that SIA was correlated not only with incision width (P < 0.05) but also with preoperative corneal hysteresis (P < 0.01). The corneal resistance factor was significantly reduced with a direct corneal incision compared with a constructed incision (P < 0.01).
They say the results indicate that corneal elasticity plays a crucial role in surgically induced refractive changes, which suggests that biomechanical analysis of the cornea can be a new tool to better predict the refractive results of cataract surgery.