Many years ago, incisions for cataract surgery were made in the sclera, even for the small phaco incisions. The scleral tunnel incisions have the advantage of being vascular which can help in long-term sealing and they are useful to avoid cutting the cornea. Even when we perform our corneal phaco incisions, we like to barely nick the limbal vessels to help long-term incision stability.
This patient has prior radial keratotomy with 16 incisions in the cornea. These are about 90% depth and we must be careful to avoid touching them during cataract surgery lest they rip open and leak. For that reason, we are doing a scleral tunnel incision to avoid the cornea. But there is an additional challenge because the approach of the instruments through this incision is flatter and less angled compared to our traditional corneal phaco incisions. We use incisions to close this incision in two layers: a buried 10-0 nylon suture in the sclera and then an 8-0 vicryl suture to close the conjunctiva, which will dissolve in a few weeks. A scleral incision this small does not need to be sutured, but the stability is increased and the induced astigmatism is less if we place the stitch.
click below to learn how to perform a scleral tunnel incision: