Cornea
Keratoconus
Also known as: keratoconus, KC, corneal ectasia, ectasia, irregular astigmatism, cross-linking referral, CXL, corneal hydrops
Filed as: Soon
Source-cited from the record's own evidence list. Clinical content programme led by Dr Ankit Mathur, PhD, Grad Cert Ocu Thera, B.S. Optom. How the clinical content is governed
Clinical decision support only
Overview
Progressive corneal ectasia producing thinning and irregular astigmatism, typically presenting from the teens to the third decade and strongly associated with eye rubbing and atopy. Early detection matters because corneal cross-linking can halt progression while vision is still good — the cost of a missed year is usually paid in lines of best-corrected acuity.
Recognition
Symptoms: what patients report
- Progressive blur that spectacles no longer fully correct, often asymmetric between the eyes.
- Frequent prescription changes with rising cylinder and shifting axis.
- Ghosting, monocular doubling, haloes, and streaking around lights.
- A history of vigorous eye rubbing, allergy, eczema, or asthma.
- In acute hydrops: sudden pain, photophobia, watering, and a marked drop in vision in one eye.
Signs: what the examination shows
- Scissor reflex on retinoscopy and irregular keratometry mires — often the earliest chair-side clues.
- Inferior or inferotemporal corneal steepening with asymmetric bowtie patterns on topography; skewed radial axes.
- Corneal thinning, thinnest point displaced from centre (pachymetry).
- Fleischer ring (iron deposition at the cone base) and Vogt striae (vertical stress lines that blanch with pressure).
- Spectacle best-corrected acuity reduced while a rigid lens over-refraction restores it — the signature of irregular astigmatism.
- Munson's sign (lower lid protrusion in downgaze) in advanced disease; acute stromal oedema in hydrops.
What OptoGuide™ covers for keratoconus
- Pattern reasoning: what this combination of findings points to, and its differentiators
- Don't-miss risks and escalation triggers
- Management tiers with linked Australian therapeutics
- Referral urgency, specialty, and letter drafting
Sources
- Keratoconus — EyeWiki
- Anterior Eye Disease and Therapeutics A-Z (Bruce & Loughnan) — standard reference text
- Is it really keratoconus or pseudo-keratoconus? – Topographic mimicry. Wykrota AA, Seitz B, Flockerzi E. Graefe's Archive for Clinical and Experimental Ophthalmology = Albrecht Von Graefes Archiv Fur Klinische Und Experi
- Pellucid Marginal Degeneration Versus Keratoconus: Distinction With Wide-Field SD-OCT Corneal Sublayer Pachymetry. Mohr N, Shajari M, Krause D, et al. The British Journal of Ophthalmology. 2021;105(12):1638-1644.
- Distinguishing Between Contact Lens Warpage and Ectasia: Usefulness of Optical Coherence Tomography Epithelial Thickness mapping. Schallhorn JM, Tang M, Li Y, et al. Journal of Cataract and Refractive Surgery. 2017;43(1)
Standard texts: Kanski's Clinical Ophthalmology: A Systematic Approach, The Wills Eye Manual, Oxford Handbook of Ophthalmology, Oxford American Handbook of Ophthalmology, Signs in Ophthalmology: Causes & Differential Diagnosis.