[Cryocoagulation in therapy of proliferative diabetic retinopathy]

The importance and indication of panretinal photocoagulation in proliferative diabetic retinopathy is well established. In contrast the indication of cryotherapy in this disease is more controversial especially in regard of new indications for early vitrectomy. The present study was performed to characterize the clinical possibilities and limitations of cryotherapy in complicated proliferative diabetic retinopathy.

In 231 patients with proliferative diabetic retinopathy and vitreous hemorrhage limiting further photocoagulation the visual outcome and diabetic retinal changes were observed before and after cyrotherapy (15-20 effects) of the ophthalmoscopically visible peripheral retina.

After cryotherapy regression of active proliferations could be seen in 70% of the patients. Resorption of vitreous hemorrhages could be found in 80% of the patients. This was associated with improvement in visual acuity in 50-60% of the patients. Loss of vision was caused due to tractional detachment in 20% of the patients and due to further vitreous hemorrhages in 10% of the patients. Comparison of retinal changes between patients with worsened visual acuity and patients with increase in visual acuity demonstrated the preoperative fibrotic status of disc neovascularisation as the most important prognostic factor. The development of central tractional detachment was significantly higher in patients with preoperatively partly regressed disc neovascularisation.

Cryotherapy of the peripheral retina in proliferative diabetic retinopathy with vitreous hemorrhages is therefore only indicated after ophthalmoscopical or echographical exclusion of peripapillary fibrosis and retinal traction and with sufficient visibility of the peripheral retina for the application.