Editor,—We thank Ergun and Stur1 for their interest in our paper and agree with their comments that it is not possible to directly compare a pilot study with the results of a randomised controlled study. We also pointed out in our conclusion that studies such as this one cannot prove efficacy of a treatment but can only indicate fruitful areas of further research. We also pointed out that the angiographic follow up data were not complete, as once membrane closure was obtained the patients were followed up clinically.

The issue of the laser spot size in transpupillary thermotherapy (TTT) is confusing; however, it is known that more irradiance (W/cm²) is needed for smaller laser spots because heat conduction from choroidal blood flow cools smaller spots more efficiently than larger spots.2 This physiological phenomenon was established in experiments,3theoretical,4 and clinical5 studies. Furthermore, it is true that overlapping zones occur when multiple spots are used for very large treatment areas. None the less, these zones experience the same temperature rise as every other treated area and no clinical abnormalities have been noted in the small overlapping zones. Although TTT is mainly used for occult membranes our results indicate that it may have a place in classic membranes and in this study stabilisation of vision was obtained in the majority of these patients and in a minority an improved vision was noted.