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The Greek physician Hippocrates, the father of modern medicine, is believed to have been the first to introduce the principle, ‘First, do no harm’, in relation to the management of disease. In my Presidential Address I shall apply this principle to the management of keratoconus, an enigmatic condition that has fascinated me since the early days of my career in optometry.

Keratoconus is the most common of the ectatic corneal degenerations, which also encompass keratoglobus, pellucid marginal degeneration and post-Lasik ectasia. It is a progressive, asymmetric condition which is non-inflammatory and usually bilateral. Keratoconus is characterised by axial corneal ectasia, myopia and irregular astigmatism. It should be distinguished from pellucid dystrophy, which is a chronic and less progressive form of corneal degeneration affecting the inferior peripheral cornea.

The onset of keratoconus usually occurs at puberty and the condition progresses to the third or fourth decade of life. It is linked with associated conditions, particular atopy, and has definite genetic patterns, being more common among males and among some ethnic groups. Prevalence in the Caucasian population in the UK has been estimated at one in 2,000 [1].

Keratoconus is also associated with other syndromes, such as Down’s, Leber’s and Ehlers-Danlos, and with osteogenesis imperfecta. Inheritance is commonly said to be autosomal and dominant but with considerable variation. The condition is therefore likely to be caused by multiple gene defects.

The morbidity of keratoconus is blurred, distorted vision, an abnormal reflex on retinoscopy and irregular, changing astigmatism. The keratoconic cornea shows characteristic corneal topography: keratometry mires are irregular and computerised topography demonstrates central corneal steepening, inferior-superior power asymmetry and skewing of the steepest meridian. Slit-lamp examination of the cornea may reveal stromal thinning and protrusion, Vogt’s striae, Fleischer’s ring, apical scarring, epithelial damage and hydrops. Clinically, the condition can range in severity from forme fruste in one eye to the serious complication of ocular perforation (hydrops).

In many ways, keratoconics have a miserable life: they are often plagued with atopic conditions such as eczema and scalp problems. There is also an association between keratoconus and eye rubbing. Despite the advent of specialist rigid-gas permeable (RGP) lenses, keratoconic patients often have to endure significant ocular discomfort and the condition may progress to the point where they need corneal transplantation or other interventions.

Could a better understanding of the causes of keratoconus lead to better management of these patients and improve their quality of life?

In 1999, I attended a lecture at the annual scientific meeting of the Contact Lens Association of Ophthalmologists that put forward a new hypothesis for the causes of keratoconus. Kenney et al [2] had used immunochemistry and molecular techniques to characterise keratoconic corneas. Their hypothesis was that there was abnormal processing of the free radicals and superoxides and a build-up of destructive aldehydes or peroxynitrites within the keratoconic cornea.

The cells that were irreversibly damaged underwent apoptosis (cell death) and those damaged reversibly underwent wound healing or repair. As part of the wound healing process, various degradative enzymes and wound healing factors were up-regulated which led to focal areas of corneal thinning and fibrosis. The implication of these findings was that keratoconus was the result of ongoing chronic trauma.

In 2003, Kenney and Brown published a further paper on the cascade hypothesis of keratoconus. Under this hypothesis, the accumulation of oxidative, cytotoxic by-products caused an alteration of various corneal proteins, triggering a cascade of events: apoptosis, altered signaling pathways, increased enzyme activities and fibrosis. In other words, the physiopathology of keratoconus came from a cascade of disparate pathways.

Based on their evidence, the authors suggested that keratoconus patients should minimise their exposure to oxidative stress. Protective steps should include wearing ultraviolet (UV) protection (in contact lenses and/or sunglasses), minimising the mechanical trauma (eye rubbing, poorly fit contact lenses) and keeping eyes comfortable with artificial tears, non-steroidal anti-inflammatory drugs and/or allergy medications.

These authors continue to publish further papers, most recently on the effects of oxidative products on fibroblasts, but their 2003 paper in this journal was the seminal publication on the topic.       

In the light of this work, let us look at the clinical implications of the principle, ‘First, do no harm’, for keratoconus patients. Could it be that we are making keratoconic patients worse by disrupting and insulting their corneas? Would a more conservative and holistic approach to management be more beneficial?

Based on these authors’ findings, our clinical mission should be to reduce the sources of reactive oxygen species in the corneas of keratoconus patients. We need to minimise corneal insult and trauma by ensuring UV protection, managing atopy and the ocular surfaces, considering spectacles or soft contact lenses as corrective options, and paying attention to nutrition and lifestyle.

Managing any associated atopic and ocular surface conditions should be the first priority. Lid and facial hygiene measures, mast-cell stabilisers, systemic regimes such as tetracycline, immunospressives etc, non-steroidal anti-inflammatories, fluorometholone, ocular lubricants and diet are among the management options available. Treating these conditions should also help to reduce eye rubbing. Only when we have stabilised and restored the ocular surface can we move on to effective management.

 If spectacles can be used to correct vision, consider high-index lenses with special lens forms, small apertures and coatings, and always incorporate a UV inhibitor. Beyond spectacles, the first choice for keratoconics should be soft rather than rigid gas-permeable contact lenses. There is a wide range of toric soft lenses available, from daily disposables to custom-made designs with high cylinder powers, which work quite well for these patients.  

 A further aspect of our holistic approach is to consider nutritional consultation to identify and eliminate any food allergies or sensitivities and assess the patient’s digestive health, which is often compromised in keratoconus patients. General nutritional advice might be to increase intake of fresh fruit and vegetables and avoid exposure to external oxidation factors such as tobacco smoke and alcohol. Nutritional supplements such as vitamin C, pro-biotics, fish oils and anti-oxidants may also be recommended. 

In summary, my essential message is to be kind to keratoconics. I believe that rigid contact lenses have only a small role in the modern management of this condition. With attention to the ocular and systemic conditions associated with keratoconus and a conservative approach to optical correction, the patient can be made more comfortable and, in many cases, the disease does seem to be stabilised. Other optical and surgical approaches to managing keratoconus may ultimately be needed but, in my view, the principle of ‘First, do no harm’ should always apply to this debilitating and distressing condition.   

References

[1] Pearson RM et al, 2000. B.C.L.A.  Journal   [« back]

[2] Kenney MC, Brown DJ and Rajeev B. Everett Kinsey lecture. The elusive causes of keratoconus: a working hypothesis. CLAO J 2000;26(1):10-3.  [« back]

[3] Kenney CM and Brown DJ. The cascade hypothesis of keratoconus. Cont Lens Ant Eye 2003;26(3);139-46.

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