Sir,

We thank Dr Khan1 for his comments regarding our paper.2 In the context of retinal detachments (RD) where the break is not clinically detectable, the issue is balancing the risk of inevitable persistent RD and vision loss, against the use of a technique that will allow the break to be identified while causing minimal complications. There is no standard accepted technique at this time. Although Fourier domain OCT can show attenuation, alteration, and disruption of the junction line between photoreceptor outer segment/inner segment (OS/IS), however, the correlation of these findings with postoperative vision remains inconsistent and most reports continue to include examples of exceptions to statistical trends.3

The decision to use dye at our centre was made after the data on Trypan blue (at a higher concentration than used in our series) injection was available.4 The use of this dye was later reported in >45 patients.5 Before adopting the use of the dye at our centre, the senior author used either silicone oil or encirclement. Both techniques were associated with their own complications; the latter was only effective in 60% of cases in this group of patients and often associated with pain.

Penha et al's6 investigation was in the context of macular holes. Toxicity is more relevant in the macular area and the dyes were shown to cause RPE atrophy in the areas that the subretinal bleb was created. Trypan blue caused the least amount of toxicity of the dyes investigated. In the context of identifying clinically undetectable breaks that are most likely to be peripheral, and possibly associated with atrophic retinal areas that have had previous cryotherapy, the risk of further peripheral RPE atrophy caused by dye toxicity needs to be balanced against the risk of persistent RD and visual loss if the break is not found. Regardless of the use of dye, the RD itself may cause disruption to the microanatomy (OS/IS junction).7, 8

Finally, with respect to the occurrence of retinal breaks near to areas of cryopexy, we simply chose to report our findings rather than attempt to draw any conclusions, as the number of cases were thankfully small.