KERATOCONUS

The cornea, the transparent structure at the front surface of the eye, is responsible for the majority of the eye's focusing power and plays a critical role in producing a clear retinal image (1,2). While significant individual variation exists in the size and shape of human corneas, commonly leading to refractive error such as astigmatism, irregular distortion and growth of the cornea can have more profound effects upon visual function and ocular health(3-6). This is the case in keratoconus- an ectatic condition of the cornea in which the cornea starts to thin and protrude in a disordered way, causing significant distortion and glare (7). 

Affecting approximately 1.4 in 1000 individuals, keratoconus is much more than a simple refractive error- it is a progressive disorder in which the cornea gradually becomes thinner and assumes an increasingly irregular shape over time(8-11). As the cornea loses its normal structural stability due to thinning of the stromal layer, it may protrude forward and develop increasing amounts of irregular astigmatism. These changes can significantly affect the quality of vision and often result in progressive visual distortion that cannot always be fully corrected with conventional spectacles alone. If not detected early and treated with an evidence- based approach, keratoconus can have an immense impact on daily activities and ocular health (12,13). Nevertheless, extremely effective treatments now exist for managing keratoconus and addressing the visual symptoms that accompany it (14,15). 

Keratoconus most commonly develops during adolescence or early adulthood, although the age of onset and rate of progression vary considerably between individuals (15, 16). Keratoconus has both genetic and environmental etiologies, and is strongly associated with atopic conditions such as asthma and eczema. Evidence has demonstrated that eye rubbing can significantly increase the risk of development of keratoconus (17). Because keratoconus frequently has subtle symptoms in the initial stages, and progresses during the years associated with education, career development and increasing visual demands, timely diagnosis and appropriate management are essential for preserving long-term visual function. 

At Onèj Optometry, comprehensive keratoconus assessment includes detailed evaluation of visual function, refractive status and corneal shape. Corneal topography implementing the Medmont Meridia provides highly detailed mapping of the corneal surface, enabling subtle changes in corneal curvature and symmetry to be identified. These measurements are invaluable for early keratoconus detection, recommending individualised treatments such as spectacles or specialty contact lenses to optimise vision, referring for early ophthalmological intervention, and monitoring disease progression.

  • The cornea is composed of highly organised collagen fibres that provide both transparency and structural strength. In keratoconus, weakening of the corneal architecture results in progressive thinning and distortion of the corneal surface (18). Many patients with keratoconus initially present with frequent prescription changes, increasing astigmatism or reduced visual quality despite obtaining new spectacles. Because the earliest stages of disease may be subtle, keratoconus can occasionally remain undetected during routine examinations if specialised corneal assessment is not performed. Early diagnosis is particularly important because treatment options capable of slowing or halting disease progression are generally most effective before significant corneal distortion develops.


    Although the exact cause of keratoconus remains incompletely understood, both genetic and environmental factors appear to contribute to disease development. A family history of keratoconus, chronic eye rubbing, allergic eye disease and certain connective tissue disorders have all been associated with an increased risk of developing the condition(12-18). Patients who experience persistent ocular itching or rubbing should be particularly mindful of the potential impact these behaviours may have upon corneal health.


    Modern management of keratoconus has evolved considerably over recent decades. Whilst spectacles may provide adequate vision during the earliest stages of disease, additional interventions are often required as corneal irregularity progresses. Specialised contact lenses may improve visual quality by creating a more regular optical surface, whilst treatments such as corneal collagen cross-linking aim to strengthen the cornea and reduce the likelihood of further progression(19,20). In selected cases, advanced surgical procedures including Corneal Allogenic Intrastromal Ring Segments (CAIRS) and other corneal interventions may be considered as part of a broader management strategy under the care of a corneal specialist (21,22).


    Because keratoconus often progresses gradually, repeated measurements over time are frequently required to accurately assess disease behaviour. Monitoring allows clinicians to identify meaningful changes in corneal structure before substantial deterioration in visual function occurs. This information is critical when determining the most appropriate management pathway for each individual patient.


    At Onèj Optometry, we believe that successful keratoconus management requires both advanced diagnostic assessment and collaborative care. We work closely with ophthalmologists and corneal specialists experienced in the management of keratoconus, including those providing treatments such as corneal collagen cross-linking and CAIRS procedures. Through careful monitoring, timely referral and ongoing communication between healthcare providers, patients are supported throughout every stage of their management journey.


    If you have noticed progressive changes in your prescription, increasing astigmatism, declining visual quality or a family history of keratoconus, a comprehensive eye examination will help determine whether further corneal assessment is warranted. Through detailed evaluation, advanced corneal imaging and evidence-based management, early identification of keratoconus is possible, providing the greatest opportunity to preserve visual quality and support long-term ocular health.

References

  1. DelMonte, D. W., & Kim, T. (2011). Anatomy and physiology of the cornea. Journal of cataract & refractive surgery, 37(3), 588-598. 

  2. Nishida, T., Saika, S., & Morishige, N. (2021). Cornea and sclera: anatomy and physiology. Cornea, 1, 1-22. 

  3. Collins, M., Vincent, S., & Read, S. (2017). The cornea. In Handbook of Visual Optics, Volume One (pp. 201-222). CRC press. 

  4. Mashige, K. P. (2013). A review of corneal diameter, curvature and thickness values and influencing factors. African Vision and Eye Health, 72(4), 185-194. 

  5. Wang, L., Dai, E., Koch, D. D., & Nathoo, A. (2003). Optical aberrations of the human anterior cornea. Journal of Cataract & Refractive Surgery, 29(8), 1514-1521. 

  6. AlMahmoud, T., Priest, D., Munger, R., & Jackson, W. B. (2011). Correlation between refractive error, corneal power, and thickness in a large population with a wide range of ametropia. Investigative ophthalmology & visual science, 52(3), 1235-1242. 

  7. Santodomingo-Rubido, J., Carracedo, G., Suzaki, A., Villa-Collar, C., Vincent, S. J., & Wolffsohn, J. S. (2022). Keratoconus: an updated review. Contact Lens and Anterior Eye, 45(3), 101559. 

  8. Rozema, J. J., Hershko, S., Tassignon, M. J., EVICR. net, Project Gullstrand Study Group, Lorenz, K., von Trentini, M., ... & Fogliato, G. (2019). The components of adult astigmatism and their age‐related changes. Ophthalmic and Physiological Optics, 39(3), 183-193. 

  9. Sinjab, M. M. (2018). Introduction to astigmatism and corneal irregularities. In Customized laser vision correction (pp. 1-64). Cham: Springer International Publishing. 

  10. Rabinowitz, Y. S. (1998). Keratoconus. Survey of ophthalmology, 42(4), 297-319. 

  11. Gothwal, V. K., Gujar, R., Sharma, S., Begum, N., & Pesudovs, K. (2022). Factors affecting quality of life in keratoconus. Ophthalmic and Physiological Optics, 42(5), 986-997. 

  12. Singh, R. B., Koh, S., Sharma, N., Woreta, F. A., Hafezi, F., Dua, H. S., & Jhanji, V. (2024). Keratoconus. Nature Reviews Disease Primers, 10(1), 81. 

  13. Almusawi, L. A., & Hamied, F. M. (2021). Risk factors for development of keratoconus: a matched pair case-control study. Clinical Ophthalmology, 3473-3479. 

  14. Kha, R., Kandel, H., & Watson, S. (2026). Trends in the Management of Keratoconus in Australia. Ophthalmic and Physiological Optics, 46(2), 135-142. 

  15. Bui, A. D., Truong, A., Pasricha, N. D., & Indaram, M. (2023). Keratoconus diagnosis and treatment: recent advances and future directions. Clinical Ophthalmology, 2705-2718. 

  16. Hashemi, H., Heydarian, S., Hooshmand, E., Saatchi, M., Yekta, A., Aghamirsalim, M., ... & Khabazkhoob, M. (2020). The prevalence and risk factors for keratoconus: a systematic review and meta-analysis. Cornea, 39(2), 263-270. 

  17. Najmi, H., Mobarki, Y., Mania, K., Altowairqi, B., Basehi, M., Mahfouz, M. S., & Elmahdy, M. (2019). The correlation between keratoconus and eye rubbing: a review. International journal of ophthalmology, 12(11), 1775. 

  18. Vought, R., Greenstein, S. A., Gelles, J., & Hersh, P. S. (2025). The pathophysiology of keratoconus. Cornea, 44(2), 137-143. 

  19. Vinciguerra, R., Pagano, L., Borgia, A., Montericcio, A., Legrottaglie, E. F., Piscopo, R., ... & Vinciguerra, P. (2020). Corneal cross-linking for progressive keratoconus: up to 13 years of follow-up. Journal of Refractive Surgery, 36(12), 838-843. 

  20. Papachristoforou, N., Ueno, A., Ledwos, K., Bartuś, J., Nowińska, A., & Karska-Basta, I. (2025). A review of keratoconus cross-linking treatment methods. Journal of Clinical Medicine, 14(5), 1702. 

  21. Yesilirmak, N., Kara, N., Aksoy, B. E., & Ulusoy, D. M. (2026). Corneal allogenic intrastromal ring segments improve visual and topographic outcomes in advanced keratoconus: Short Title: CAIRS in Advanced Keratoconus. Scientific Reports. 

  22. Friedrich, M., Auffarth, G. U., Soiberman, U., Augustin, V. A., Khoramnia, R., & Son, H. S. (2025). Visual and Topographic Outcomes After Corneal Allogeneic Intrastromal Ring Segments for Keratoconus: A Systematic Review and Meta-Analysis. American journal of ophthalmology, 276, 81-91.