# Fluid-Assisted Hydro-Bubble Technique With Newly Designed Cannula for Deep Anterior Lamellar Keratoplasty

## TL;DR

A new hydro-bubble technique using a specially designed cannula was tested for corneal surgery, showing promising results in safely exposing the Descemet's membrane.

## Contribution

A novel fluid-assisted hydro-bubble technique with a redesigned cannula for deep anterior lamellar keratoplasty is introduced and evaluated.

## Key findings

- Hydro-bubble formation was successful in 84.6% of patients using the new cannula.
- Mean endothelial cell density at one month post-surgery was 1847 ± 622.1 cells/mm².
- Intraoperative microperforation occurred in 15.4% of cases, but no macroperforation or conversion to penetrating keratoplasty was observed.

## Abstract

Purpose

This study was conducted to evaluate the efficacy and safety of the novel hydro-bubble technique (fluid-assisted Descemet’s membrane (DM) exposure) with a newly designed cannula for inducing bare DM during deep anterior lamellar keratoplasty (DALK).

Methods

This retrospective study evaluated the results of DALK in which the hydro-bubble technique (fluid-assisted DM exposure) was performed with a newly designed cannula between April 2018 and March 2020. A femtosecond laser was used to create an initial incision with minimal remaining parenchyma. Balanced salt solution (BSS) was injected into the parenchyma using the newly designed cannula to induce bare DM. The success rate of hydro-bubble formation, visual outcomes, endothelial cell density, and complications were analyzed.

Results

The study included 39 patients with corneal opacity (n=19), corneal dystrophy (n=13), or keratoconus (n=6). Hydro-bubble formation was induced in 33 (84.6%) of these patients. At one year postoperatively, visual acuity was substantially better; the mean endothelial cell density at one month postoperatively was 1847 ± 622.1 cells/mm2. Intraoperative microperforation occurred in six cases (15.4%), but there were no instances of macroperforation or conversion to penetrating keratoplasty. Postoperative complications included a higher incidence of double anterior chamber, which was often associated with type 2 bubbles.

Conclusion

The hydro-bubble technique (fluid-assisted DM exposure) with a newly designed cannula is a promising alternative for inducing bare DM during DALK. It achieves a hydro-bubble formation success rate similar to the rate for the conventional big-bubble technique, while allowing greater control over hydro-bubble formation size and increasing visibility during surgery. Although further validation is needed, the enhanced safety and effectiveness of the hydro-bubble technique (fluid-assisted DM exposure) can facilitate better surgical management of corneal stromal pathologies.