Симптом «шипа» — для прогнозирования формирования большого пузыря при глубокой передней ламеллярной кератопластике при запущенном кератоконусе

Spike sign - To predict the formation of big bubble in deep anterior lamellar keratoplasty in advanced keratoconus.

Corneal transplantation has shown immense improvements in long-term outcomes, which has been largely contributed by a shift toward lamellar corneal surgeries over penetrating keratoplasties (PK).[¹,²] Lamellar corneal grafts involve the transplantation of a section of the cornea – anterior part or posterior part in anterior lamellar or endothelial keratoplasties, respectively. As the amount of tissue transplanted is comparatively less, this reduces the antigenic load and immune response by the recipient tissue and the chance of rejection compared to a PK. In addition, in deep anterior lamellar keratoplasty (DALK), most of the stroma is replaced while preserving the patient’s own endothelium, which is largely responsible for the rejection episodes.[³] Compared to PK, DALK has a reduced risk of endophthalmitis, expulsive hemorrhage, and anterior chamber inflammation.[⁴] The results of DALK have been very gratifying, with good long-term outcomes and a low risk of rejection at 5 years.[⁵] Due to these advantages, DALK has become the procedure of choice in all conditions requiring a corneal transplant where the pathology is limited to the anterior part of the cornea and the endothelium is healthy.[⁶] Advanced keratoconus is one of the common etiologies for which DALK is performed and has been found to have excellent long-term outcomes for the same. There are various techniques by which the DALK dissection can be done, of which the big bubble technique described by Anwar and Teichman is one of the most popular.[⁷] It is a very elegant technique that allows the surgeon to bare the descemet’s membrane (DM)–endothelium complex with minimal residual stroma. This gives the patient faster visual recovery and good anatomical stability post procedure. The big bubble technique can be a little daunting for surgeons in the learning phase as there is a risk of perforating the DM–endothelial complex intraoperatively or not obtaining the bubble, necessitating a manual dissection of the stroma. The presence of a corneal scar, the location of the needle tip, and the severity of keratoconus can all vary the chances of big bubble formation and its appearance during formation. Understanding the dynamics of the injected air is crucial to obtaining a repeatable big bubble intraoperatively. In this paper, we describe a unique sign noted at the commencement of the formation of a big bubble, which gives the surgeon a clue to successfully achieve a big bubble without complications. It is very useful, especially in the learning phase of a surgeon.