At the completion of this article, the reader should be able to…
• Identify early signs and symptoms of keratoconus and recognise at-risk patient groups in clinical practice.
• Determine when referral for corneal cross-linking (CXL) is indicated and understand its role in preventing progression.
• Implement appropriate follow-up strategies and use registry data to monitor outcomes and benchmark care.
Professor Stephanie Watson OAM
Head, Ophthalmology and head of Corneal Research Group
The University of Sydney
Head, Corneal Unit, Sydney Eye Hospital
Chair, NSW RANZCO
Chair, Australian Vision Research
Himal Kandel
Kornhauser research fellow
Post-doctoral researcher,
Corneal Research Group
The University of Sydney
Professor Stephanie Watson OAM and Himal Kandel bring together clinical trial evidence, registry data and consensus guidance to guide optometrists through practical care of keratoconus.
Patients with keratoconus want to improve their vision, limit progression and maintain their quality of life. Notably, the impact on quality of life of keratoconus can be greater than in macular diseases.1
This article synthesises evidence from clinical trials, the Save Sight Keratoconus Registry and Second Global Consensus on Keratoconus to support clinicians in the effective management of patients with keratoconus.
Does my patient have keratoconus?
Every day in your practice, it’s important to consider whether one of your patients has keratoconus. It is relatively common, with a global pooled prevalence of 8.16 per 1,000 population and affecting one in 84 Australians aged 20 years.2
Given that its onset is typically in childhood or in young adults, a high index of suspicion is warranted in these groups. Diagnosis begins by history taking and assessment of risk factors before moving on to clinical examination and corneal imaging. Patients typically report blurred or distorted vision and increased light sensitivity, often accompanied by frequent refractive changes, particularly progressive astigmatism.
Common risk factors include eye rubbing, atopy, family history, and consanguinity, as well as conditions such as trisomy 21 (Down’s syndrome).
Subjective refraction should then be performed, noting whether pinhole vision exceeds vision with spectacle refraction, which may indicate irregular astigmatism which occurs in keratoconus.
The amount of astigmatism is also informative, with more than 2D of astigmatism – particularly in children – raising suspicion of the condition.
Corneal findings are often unremarkable in early keratoconus, with clinical signs becoming more apparent as the disease progresses.
Retinoscopy may reveal an oil-drop sign (Figure 1) or scissoring. Signs on slit lamp examination include Vogt’s striae (Figure 2), apical thinning and scarring (Figure 2), and a Fleischer ring (Figure 3).
Munson’s sign, which is bulging of the lower lid from the cone in downgaze, is only present in advanced disease.
Atopic keratoconjunctivitis may be present with a papillary conjunctival reaction with hyperaemia.
Keratometry on autorefraction or traditional keratometry can identify steep corneas with >50D indicating potential keratoconus.
However, readings may appear normal early if the cone is not central. Complete imaging of corneal shape and thickness is needed to diagnose keratoconus.
Modern tomographers such as the Pentacam and Galilei, topographers and now anterior segment OCT have inbuilt algorithms to confirm the diagnosis.
While maximum corneal curvature (Kmax) is the most commonly used measure, it may not be reproducible in all cases. Gaussian and Tangential corneal maps provide a better indication of corneal shape than axial maps (Figure 4).
In tangential maps, each measured data point is calculated at 90 degrees tangent to its surface to highlight small changes in shape.
Tip: A normal K2 (central reading) does not exclude keratoconus as the cone may not involve the central cornea.
If the diagnosis is uncertain, patients may be classified as having subclinical keratoconus, forme fruste keratoconus or as keratoconus suspects (Table 1).
Tip: Keratoconus is common. Have a high index of suspicion especially in children and young adults with myopia and/or astigmatism > 2D and/or keratometry >50D even with a normal slit lamp corneal examination.
Patient management
Key steps in the management of keratoconus are assessing for and treating progression, visual rehabilitation and optimising any comorbidities such as atopic eye disease. The broader impact on mental health should also be recognised,3 and support arranged via the patient’s general practitioner if needed.
Progression management
Our systematic review with meta-analysis and Save Sight Registry data found that steeper Kmax and younger age were the most clinically useful baseline predictors of progression; both were associated with worsening of two clinical parameters (Table 2).
A Kmax greater than 55D and younger age – for example, 21 years compared with 26 years – are linked to a higher risk of progression.4,5 Both K2 and Kmean are also sensitive measures of progression, which could occur in less than 12 months, underscoring the need for short corneal cross-linking (CXL) waitlists.
Tip: Patients younger than 17 and those with Kmax greater than 55D warrant closer monitoring and a lower threshold for CXL, given their higher risk of progression.
Corneal cross-linking
Corneal cross-linking (CXL) is the gold standard treatment for patients with progressive keratoconus or those at high risk of progression.
Its efficacy and safety in preventing progression – and in some cases improving vision – have been established in clinical trials.6
Due to the high risk of progression in paediatric patients, CXL is performed soon after diagnosis, with epithelium-off the most preferred technique.7
Immediate CXL is also recommended in developmentally delayed patients due to the difficulties of detecting progression.7
NSW Health has referral criteria to assist optometrists and ophthalmologists in making outpatient referrals for adult and paediatric keratoconus.8,9
These criteria emphasise the need for early referral for younger patients, those with a family history, and those demonstrating progression.
Referrals should contain details on the patient’s recent and past history, medical and ocular findings, including past refractions as detailed on the website.8,9
Following CXL, patients still require long-term follow-up as a risk of progression remains, with retreatment possible if needed.
Tip: Early referral is best when progression is likely, particularly in children
In collaboration with Keratoconus Australia, the Save Sight Registry has developed a patient brochure on CXL for keratoconus.10
Key messages are:
• CXL can prevent progression over the long term.
• CXL is generally safe, but there are risks. Around three in 100 patients may have worsening vision due to corneal haze, corneal shape irregularities, scarring, and/or infection.11
• Many protocols exist for CXL with the epithelium-off protocol having the most long-term evidence on efficacy and safety and accelerated procedures saving operative time with equal effectiveness.11
Tip: CXL is safe with good long-term outcomes in preventing progression and in many cases improving vision
Visual rehabilitation
Visual rehabilitation begins with an assessment of the patient’s visual needs and general status.
Tip: The goal is not necessarily to achieve 6/6 vision in both eyes, but to restore functional vision that meets the patient’s needs.
Non-surgical management
In early keratoconus, patients may manage with their unaided vision. In our Save Sight Registry study of 671 patients, 302 were unaided, 326 wore spectacles and 43 contact lenses.12
Although irregular astigmatism is the hallmark of keratoconus, spectacle correction may still provide adequate functional vision for some patients in daily life.
Contact lenses can be used to improve vision. If the patient has functional vision with spectacles, soft contact lenses maybe an option.
Hard contact lenses are needed to correct irregular astigmatism, particularly in cases with bilateral poor vision. Common options include corneal rigid gas permeable or scleral contact lenses. Piggyback lenses and hybrid lenses may also be needed.
Hydrops is a complication of keratoconus that can be managed with topical steroids and agents to reduce intraocular pressure.
Surgical management
Corneal grafting has been the traditional surgical treatment for keratoconus and is indicated when best corrected visual acuity is insufficient, contact lens tolerance is present, and the patient understands the risks of the procedure.
Rates of corneal grafting in keratoconus have reduced in some studies due to improved contact lens fitting and CXL.
Deep anterior lamellar keratoplasty (DALK) is preferred to penetrating keratoplasty due to lower risks of rejection and some mechanical advantage unless contra-indicated by deep corneal scarring such as post-hydrops13 (Figure 6).
Surgeons are now able to complete DALK even if microperforations occur intra-operatively.
A range of surgeries have emerged as options in keratoconus, including laser, phakic intraocular lenses, pinhole intraocular devices, intrastromal ring segments (synthetic or donor-based (CAIRS)) and stromal transplantation procedures.
Toric phakic intraocular lenses can be considered if there is more than 2D regular astigmatism.
CXL has been performed before, during and after a range of these procedures with evidence still needed to determine the best approach.
Patients with keratoconus may develop cataract (Figure 7).
When the keratometry exceeds 50D, informed consent should include that biometry for intraocular lens selection has reduced predictability and a multi-formula approach should be used.
If there is sufficient regular astigmatism which is supported by a history of good spectacle vision (>6/12) prior to the cataract, a toric intraocular lens may be appropriate.
Patients who previously relied on rigid hard contact lenses will likely still need their lenses post-operatively to correct irregular astigmatism. Prior to surgery, contact lens wear should be discontinued for biometry, with tailored time periods according to lens type.14
Tip: Visual rehabilitation in keratoconus should be tailored to meet the patient’s needs
Long-term management
Patients with keratoconus require long-term follow-up with the frequency of visits determined by their risk of progression and treatment needs.
In children and adolescents, progression can occur within months necessitating a two-to-three month follow-up interval.
Eye rubbing can increase the risk of progression, necessitating close follow up due to increased risk.
As the patient approaches 30 years of age, the follow-up interval can be reduced to annually. In all cases, patients should be advised to return for review if they notice changes in their vision.
Tip: Close follow-up is needed in the young as progression can occur rapidly.
How can I track and benchmark my outcomes?
The Save Sight Keratoconus Registry is a web-based tool that can be used to track your patients’ outcomes, benchmark your practice against national and international clinicians, and share data between ophthalmologists and optometrists (Figure 9).
A range of keratoconus treatments can be audited with the registry, including cross-linking, corneal grafting, laser and ring segments.
The optometry module can be used by optometrists to track outcomes of refractive measures such as contact lenses.15
Registry users can obtain accreditation towards their Continuing Professional Development requirements with Optometry Australia and the Royal Australian and New Zealand College of Ophthalmologists.
Users can also contribute to research publications from the registry data.
Figure 8: Sign up page for Save Sight Keratoconus Registry
Patient-reported outcomes are collectable with the registry using the Keratoconus Outcomes Research Questionnaire (KORQ).
Keratoconus has multifaceted impacts on a patient’s quality of life.16 KORQ can be completed on paper and entered into the registry or patients can use an iPad or their own device to complete it.
The advantage of capturing patient-reported outcomes is that clinicians can obtain a validated assessment of their patients’ functioning and treatment benefits.
Tip: You can use your own real-world evidence to benchmark your patient’s keratoconus care.
The management of patients with keratoconus is rewarding, as clinicians now have a range of treatment options and can prevent progression and deliver improvements in their patients’ quality of life.
Join us in collecting real world evidence that can drive improvements in care via benchmarking, become a Save Sight Keratoconus Registry user.
References
1.Kandel H, Nguyen V, Piermarocchi S, Ceklic L, Teo K, Arnalich-Montiel F, et al. Quality of life impact of eye diseases: a Save Sight Registries study. Clin Exp Ophthalmol. 2022;50(4):386-97.
2. Chan E, Chong E, Lingham G, Stevenson L, Sanfilippo P, Hewitt A, et al. Prevalence of keratoconus based on Scheimpflug imaging: The Raine Study. Ophthalmology. 2021;128(4):515-21.
3. Durakovic E, Kandel H, Watson S. Mental health impact of keratoconus: A systematic review. Cornea. 2023;42(9):1187-97.
4. Ferdi A, Nguyen V, Gore D, Allan B, Rozena J, Watson S. Keratoconus natural progression: A systematic review and meta-analysis of 11,529 eyes. Ophthalmology. 2019;126(7):935-45.
5. Ferdi A, Nguyen V, Kandel H, Tan JCK, Arnalich-Montiel F, Abbondanza M, et al. Predictors of progression in untreated keratoconus: a Save Sight Keratoconus Registry study. Br J Ophthalmol. 2022;106(9):1206-11.
6. Wittig-Silva C, Chan E, Islam F, Wu T, Whiting M. A randomized, controlled trial of corneal collagen cross-linking in progressive keratoconus: three-year results. Ophthalmology. 2014.
7. Conner E, Gagrani M, Lalgudi VG, Shah PR, Hiasat J, Jhanji V, et al. Corneal Collagen Cross-linking for Keratoconus in Pediatric and Developmentally Delayed Patients. Cornea. 2024.
8. New South Wales Health. [Statewide referral criteria for adults with keratoconus]. Available from: https://www.health.nsw.gov.au/outpatients/referrals/Pages/keratoconus.aspx.
9. New South Wales Health. [Statewide referral criteria for adult and paediatric patients with keratoconus]. [Available from: chrome-https://www.health.nsw.gov.au/outpatients/referrals/Documents/full-criteria-ophtho-paediatric.pdf.
10. Australia SSRaK. Corneal cross-linking 2024 [Available from: https://www.keratoconus.org.au/wp-content/uploads/2024/11/KA-cross-linking-Brochure-2024.pdf.
11. Kandel H, Abbondanza M, Gupta A, Mills R, Watson AS, Petsoglou C, et al. Comparison of standard versus accelerated corneal collagen cross-linking for keratoconus: 5-year outcomes from the Save Sight Keratoconus Registry. Eye (Lond). 2024;38(1):95-102.
12. Goh N, Kandel H, Watson S. Visual aids in keratoconus: A Save Sight Keratoconus Registry study. Clin Exp Ophthalmol. 2025;53:78-161.
13. Watson S, Ramsay A, Dart J, Bunce C, Craig E. Comparison of deep lamellar keratoplasty and penetrating keratoplasty in patients with keratoconus. Ophthalmology. 2004;111(9):1676-82.
14. Abid A, Kandel H, Watson S. Systematic review investigating the time taken for corneal stabilisation following contact lens cessation. Br J Ophthalmol. 2025;109(10):1099-108.
15. Kandel H, Downie LE, Watson SL. The Save Sight Keratoconus Registry – Optometry Module: an opportunity to use real-world data to advance eye care. Clin Exp Optom. 2022;105(1):96-9.
16. Fan L, Kandel H, Watson S. Impacts of keratoconus on quality of life: a qualitative study. Eye (Lond). 2024;38:3136-44.
