The ‘big-bubble’ deep anterior lamellar keratoplasty (DALK) technique paved the way to redefine corneal anatomy by discovery of a new ‘pre-Descemet/Dua’s layer’. The study of evolution and morphology of these bubbles led them to be classified into three types [1]. Type-1 bubble is a dome-shaped elevation that forms centrally, spreading centrifugally between the stroma and pre-Descemet layer, while the type-2 is a larger, clear-edged thin-walled bubble, forming peripherally and expanding centripetally between the pre-Descemet layer and the Descemet membrane (DM). The third uncommon type is the ‘mixed bubble’ where usually there is a primary type-1 bubble along with a secondary type-2 bubble, which may even be hidden under the semi-opaque former one [1, 2]. This identification is important to foresee the specific complications such as the higher tendency of bursting of the type-2 component. Though studied extensively, yet they have been rarely documented in vivo [1,2,3].

The most common and preferred type of big-bubble for DALK is the type-1, owing to the additional strength provided by the retained host pre-Descemet layer. A mixed bubble also confers the same advantage, but additionally provides the risk of DMD. To circumvent this, AlTaan et al. [3] suggested an intentional puncture of the pre-Descemet layer to release the type-2 air pocket off the mixed bubble. However, post-operative DMD was still noticeable when a patient incurred accidental intra-operative perforation during a mixed-bubble DALK [4]. Spontaneous resorption of the type-2 air pocket in the post-operative period has also been shown [5]. However, both these practices could not evade post-operative DMD because the mixed-type bubble intra-operatively creates an additional deeper enclosed space between the pre-Descemet layer and DM, and as both these layers are left intact, this space may potentially enlarge or be prevented from spontaneous resolution by the persistence of air or seepage of fluid. On the contrary, in pure type-1 or type-2 bubbles, when formed singly, the space created is deroofed during dissection.

Log in or create a free account to read this content

Gain free access to this article, as well as selected content from this journal and more on nature.com

Access through your institution

or

Sign in or create an account
Continue with Google
Continue with ORCiD