CORNEAL AND EXTERNAL DISORDERS: Edited by Shahzad I. MianPotential benefits of modified corneal tissue grafts for keratoconus: Bowman layer ‘inlay’ and ‘onlay’ transplantation, and allogenic tissue ring segmentsDapena, Isabela,b; Parker, Jack S.c,d; Melles, Gerrit R.J.a,b,d,eAuthor Information aNetherlands Institute for Innovative Ocular Surgery bMelles Cornea Clinic Rotterdam, Rotterdam, The Netherlands cUAB, Birmingham, Alabama dNIIOS-USA, San Diego, California, USA eAmnitrans EyeBank Rotterdam, Rotterdam, The Netherlands Correspondence to Gerrit R.J. Melles, MD, PhD, Netherlands Institute for Innovative Ocular Surgery, Rotterdam, The Netherlands. Tel: +31 10 297 4444; fax: +31 10 297 4440; e-mail: email@example.com; website www.niios.com Current Opinion in Ophthalmology: July 2020 - Volume 31 - Issue 4 - p 276-283 doi: 10.1097/ICU.0000000000000665 Buy Metrics Abstract Purpose of review Keratoconus can be surgically challenging, especially in advanced cases. Classic corneal transplantation techniques, may often be associated with complications. New alternative procedures like isolated Bowman layer transplantation (as a corneal stromal inlay or as a corneal onlay) and corneal allogenic intrastromal ring segments (CAIRS) have recently shown promising results. The aim of this review is to describe the main new surgical developments for treating keratoconus. Recent findings Intrastromal Bowman layer transplantation has recently shown to be effective in halting keratoconus progression and maintaining visual acuity with contact lenses, at least up to 5–7 years postoperatively. Because intrastromal dissection can be challenging, we have recently developed a technique that allows using Bowman layer grafts as an onlay, that is positioned onto the patient's anatomical Bowman layer or anterior stroma, achieving comparable results as with Bowman layer inlay transplantation. CAIRS may also be an effective treatment, improving visual acuity, corneal surface parameters and keratoconus progression. Summary There are currently some new alternative treatments such as isolated Bowman layer inlay or onlay transplantation and CAIRS, both of which seem effective at treating keratoconus and which may offer a less invasive surgical approach. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.