Advances in the diagnosis and treatment of keratoconus

Overview

This review, published in Therapeutic Advances in Ophthalmology in 2021, summarises emerging approaches to keratoconus described in the literature from 2017 to 2020. It deliberately leaves out treatments already in established clinical use. Keratoconus was long considered rare. Modern imaging shows it is more common than once thought, and detecting it before refractive surgery has become essential.

Advances in diagnosis

Optical coherence tomography can map the thickness of the corneal epithelium and Bowman layer, revealing early changes that the epithelium may otherwise mask. Methods for measuring corneal biomechanics, such as Brillouin spectroscopy and optical coherence elastography, aim to detect weakening before the shape of the cornea changes. They are promising but still early. Biomarkers of inflammation, tear markers and hormonal factors are being studied, challenging the view that keratoconus is purely non-inflammatory. Artificial intelligence is being used to detect and stage the disease and to combine data from several devices.

Cross-linking

Corneal cross-linking remains the main treatment to halt progression. Research focuses on its limitations: oxygen depletion during treatment, poor penetration of the photosensitising agent through intact epithelium, long treatment times and thin corneas. Solutions under study include pulsed light and supplemental oxygen, iontophoresis and other permeability enhancers, adding donor or laser-extracted tissue to thicken thin corneas, and customised, imaging-guided treatment. The standard protocol remains the reference.

Combined and surgical approaches

Cross-linking is increasingly combined with laser surface treatment or intracorneal ring segments, aiming to halt progression and improve vision at the same time. New cross-linking agents and laser-based activation are still experimental. Newer surgical options include Bowman layer transplantation for advanced disease and additive keratoplasty, which inserts a corneal lamella to thicken and flatten the cone. Cellular therapy with stem cells has shown early, preliminary results.

Clinical implications

The authors anticipate personalised treatment guided by measuring corneal strength at specific points. They emphasise prevention before vision deteriorates and greater public awareness of the disease.