Corneal integrity after refractive surgery. Effects of radial keratotomy and mini-radial keratotomy

Mini-radial keratotomy (mini-RK) involves limiting the extent of radial incisions to within 3.5 mm from the center of the central clear zone, compared with incisions that extend close to or beyond the limbus, as with "conventional" RK. This study was designed to determine if shorter incision length reduces the likelihood of corneal rupture after blunt trauma.

Sixteen fresh human anterior segments were divided into four groups and mounted onto an artificial anterior chamber. Four corneas with no incisions were used as controls, four received regular four-incision RK, four received four mini-RK incisions, and four received eight mini-RK incisions. Incisions extended from the 3.0-mm central clear zone to 1 mm inside the limbus (regular RK), or from the 3.0-mm central clear zone to the 7.0-mm mark (mini-RK). A pump slowly infused the artificial anterior chamber with a balanced salt solution while the pressure was continuously monitored with an electronic pressure transducer. The maximum pressure and the site of the rupture were recorded.

Control corneas ruptured at the limbus, whereas all surgical eyes ruptured at incision sites. The corneas subjected to mini-RK ruptured at significantly higher pressures than corneas that had undergone regular RK (P < 0.01).

Reducing incision length appears to reduce the likelihood of corneal rupture as intraocular pressure is increased. Mini-RK may be advantageous for patients at high risk for ocular trauma.