Femtosecond laser-assisted half top hat penetrating keratoplasty for keratoglobus

To describe a modified technique utilizing femtosecond laser-assisted penetrating keratoplasty for the surgical management of keratoglobus with an extremely thin peripheral cornea.

Two eyes of two patients with advanced keratoglobus underwent a modified, donor-only, top hat keratoplasty. Femtosecond laser-assisted top hat configuration was exclusively performed on the donor cornea (half top hat) and sutured under the recipient's cornea which underwent a regular full thickness trephination. Patients were followed up for 12-24 months after intervention. Visual acuity and anatomical results (measured using corneal tomography and anterior segment OCT) were evaluated after this intervention.

Post-operatively, best corrected visual acuity improved from counting fingers in the first patient and 20/720 in the second to 20/30 in both. Keratometry values markedly decreased, and peripheral thickness was augmented in both cases. No complications during the follow-up period were noted.

Top hat configuration keratoplasty on donor cornea alone may be a unique surgical solution enabling the augmentation of the peripheral cornea in keratoglobus eyes, providing good visual outcomes as well as structural integrity.