Observations after Diode Laser Photocoagulation of Parafoveal Choroidal Neovascular Membranes
Objective: To analyze 5 years experience whether the infrared diode laser at 810 nm is effective in the treatment of parafoveal choroidal neovascular membranes (CNV's).
Methods: 52 eyes of 45 patients with parafoveal CNV membranes due to AMD (age-related macular degeneration) were consecutively treated with an 810 nm diode laser by one surgeon. Follow-up was 12–60 months (mean 38 months). Treatment parameters were a spot size of 125 and 200 μm, exposure duration of 0.2–1.0 seconds and powers between 0.7 and 1.0 W. The endpoint was to produce a confluent grey-withish lesion extending to 100 m beyond the angiographically observed limits of the membrane. Each eye recieved control angiography 3 weeks after treatment for decision, if retreatment is necessary or membrane is closed.
Results: Angiographically proved closure of the membrane was achieved in 37 eyes (72%) by 1–3 treatment sessions within 3 months. Visual acuity was unchanged or better in 32 eyes (62%). 15 eyes developed subfoveal membranes resulting in poorer visual acuity. Within 12 months 5 eyes showed recurrent CNV, whereby 2 eyes revealed successful retreatment. During follow-up 28 eyes (54%) had no persistence or reccurence of CNV, 9 eyes (17%) showed recurrent CNV with successfull retreatment in 4 eyes and after all visus stabilization was achieved in 32 eyes (62%). During therapy no patient complained of light sensations or pain, which allowes for better fixation during laser therapy and minimizing the risk of unexpected macula coagulation with consecutive visual loss. The high transmission of the infrared laserlignt was demonstrated by an excellent penetration through retinal edema and thin layers of subretinal hemorrhages as well as a more intensive chorioretinal atrophy postoperatively.
Conclusions: Diode lasercoagulation is highly effective for closure of choroidal neovascular membranes due to AMD especially in presence of significant retinal edema and thin layers of subretinal hemorrhages. The risk of inadvertent damage to the fovea due to eye movements is reduced because there is no perception of light flashes by the patient during laser treatment.