Dose-Response-Relationship between Number of Laser Burns and IOP Reduction in Cyclophotocoagulation: An Animal Study

Purpose. The relationship between number of laser burns of cyclophotocoagulation (CPC) and intraocular pressure (IOP) reduction is unknown. This animal model was established to reveal a possible dose-response-relationship between the number of applied laser burns and the IOP lowering effect. Methods. 30 chinchilla bastard rabbits were divided into 5 groups and treated with either 1, 5, 10, 20, or 30 CPC burns, respectively. IOP was followed up for 1 week. IOP reduction of a single 30-burn treatment was compared with a fractionated treatment (three sessions; one week in between; 10 burns/session). Results. IOP reduction increases nonlinearly with the number of CPC burns (max. mmHg). Fractionated treatment shows similar IOP reduction with less complications and more constant results compared to single session treatment. Conclusions. The study reveals a complex relationship between IOP reduction and the number of CPC burns. Fractionated CPC gives comparable IOP reduction at a higher degree of safety.