Introduction

Have you ever felt itchy in your eyes? Maybe you are suffering from keratitis! As the number of contact lens users has skyrocketed, keratitis is a quite common condition in clinics, and it could be prevented or cured by suitable treatment. Keratitis is a painful inflammation of the cornea, the outer covering of the eye. The cornea is a dome-shaped transparent structure that protects the eyes from external threats. While keratitis could be caused by bacterial or non-bacterial reasons, hygiene maintenance is undoubtedly very important. If you are unsure whether you are suffering from keratitis, it is better to be checked by your local GP. If we ignore keratitis, untreated keratitis could damage our vision permanently. 

We would start by breaking down the causes of keratitis, the importance of hygiene and protective measures, to help you understand keratitis more.

Understanding keratitis and its causes

Cornea gets infected or injured, then the inflammation would occur, which would lead to keratitis. The cornea serves not only as a protective barrier but also plays a vital role in focusing vision. Any disruption to its clarity or shape can impair vision significantly. Keratitis is classified into infectious keratitis and non-infectious keratitis. The conditions of keratitis include redness and photophobia (increased sensitivity to light). Some patients may feel pain and irritation in their eyes. 

First of all, infectious keratitis could be subdivided into the following subcategories: acterial keratitis ( i.e Pseudomonas, Staphylococcus, Streptococcus), Protozoal keratitis, Pythium keratitis, Fungal keratitis (i.e. Aspergillus, Candida), Viral keratitis (i.e. herpes simplex virus, herpes zoster virus), and Helminths. Each of them has its own distinguishing characteristics and also shares some similarities with the other. 

For example, bacterial keratitis varies by organism. Staphylococcal keratitis may be due to direct infection or staphylococcal antigens, typically affecting the peripheral cornea (marginal keratitis) and associated with blepharitis, while Streptococcal keratitis is often linked to a blocked nasolacrimal duct, and lacrimal duct function should be assessed in most cases. Pseudomonas keratitis is caused by gram-negative bacteria, shows diffuse, dense corneal infiltration with greenish-yellow infiltrates. Nocardia keratitis presents as granular, mid-stromal infiltrates in a wreath-like pattern, often following trauma or eye surgery, especially near incision sites.

Non-infectious keratitis is contributed to by local factors (i.e. physical or chemical irritants) or systemic autoimmune conditions.

Local factors can lead to corneal ulcers through constant friction against the eye surface. Examples of the local factors are trichiatic eyelashes, entropion, and distichiasis. This condition results from mechanical irritation by giant papillae on the upper eyelid, which is easily diagnosed through lid eversion. Treatment usually involves topical steroids and lubricants. In more stubborn cases, supratarsal triamcinolone injections or even surgical excision of the papillae with conjunctival or mucous membrane grafting may be necessary. Additionally, corneal ulcers may result from foreign bodies lodged in the sulcus subtarsalis; these must be carefully removed under topical anaesthesia using slit-lamp or surgical techniques.

The examples of systemic autoimmune disorders, on the other hand, are rheumatoid arthritis (RA) and granulomatosis with polyangiitis (GPA). The serological markers, such as rheumatoid factor and anti-cyclic citrullinated peptide (anti-CCP) antibodies, are commonly found in patients' bodies. The common treatment for RA-keratitis typically begins with topical and systemic steroids, followed by immunosuppressive agents like methotrexate. GPA, a potentially life-threatening systemic vasculitis, presents with both ocular and renal involvement and is diagnosed via C-ANCA serology. Pulse therapy with cyclophosphamide is the standard treatment, supplemented by topical and systemic steroids to manage peripheral ulcerative keratitis. Also, xerophthalmia, which is caused by vitamin A deficiency, is another systemic keratitis example.

The current treatment for xerophthalmia is supplement application according to World Health Organisation (WHO) guidelines. The suitable treatment plan and diagnosis should always be sought from your GP.¹

The importance of eye hygiene in keratitis prevention

Maintaining meticulous eye hygiene remains the cornerstone of keratitis prevention, especially in contact lens wearers. There are over 140 million people using contact lenses worldwide. This stream highlights how we should pay more attention to our hygiene behaviours to prevent the development of microbial keratitis or minimise the risk of infections.^2,4

Keratitis is closely linked to improper handling and storage of contact lenses. Studies have shown that even when users follow the cleaning instructions provided by the manufacturer, contact lens storage cases can have high levels of microbial contamination. Therefore, the risk is not only hypothetical. In a randomised cross-over clinical trial, 82% of lens cases cleaned according to standard manufacturer guidelines, typically involving rinsing with multipurpose solution and air-drying, were still contaminated. In contrast, an alternative regimen that added rubbing, rinsing, tissue-wiping, and face-down air-drying significantly reduced contamination levels, with a lower median count of viable bacteria.^3,5

These phenomena highlight how the present guidelines for contact lens users still do not require improvement, and the encouragement of stricter hygiene methods should be considered. Also, according to some studies, one of the main concerns is that most multifunctional solutions have not been shown to be effective against Acanthamoeba, a free-living protozoan that is frequently discovered in soil and water.

In contrast to bacterial keratitis, the pathophysiology of Acanthamoeba is less well understood. It is important to note that Acanthamoeba keratitis can result in irreversible corneal damage and blindness if treatment is not received. This bacterium is particularly harmful.⁶

Contact lens users should follow the hygiene guidelines in order to lower risk, such as starting with properly cleaning and drying their hands before handling lenses. Never use tap water or saliva for cleaning; only use solutions that have been approved for use with contact lenses. Even "no-rub" lenses can be rubbed and rinsed to help remove microbiological contaminants. The lens case, a known reservoir for pathogens, must also be cleaned properly. As the trial above showed, incorporating tissue-wiping and face-down drying into daily case hygiene is a simple but effective step in limiting microbial growth, including that of Acanthamoeba.

The risk of keratitis is further increased by other behavioural variables. Sleeping with contact lenses, even ones designed for nighttime usage, increases the risk of infection by compromising corneal oxygenation and promoting microbial adherence. Another serious risk is exposure to water. There is a chance that waterborne pathogens, especially Acanthamoeba, will stick to the lens surface and penetrate the cornea if you wear lenses while swimming, taking a shower, or using a hot tub. Public health officials now stress that lenses should never come into contact with water.

In response to rising infection rates, initiatives like the British Contact Lens Association’s “No Water” sticker campaign aim to promote safer habits. These visual cues remind users not to expose their lenses or storage cases to tap water and have been adopted internationally, including by the American Academy of Optometry. Complementary educational efforts from online videos to social media campaigns are increasingly targeting young adults, who are statistically more likely to engage in noncompliant behaviours that raise the risk of infection.

Management of UV keratitis

High UV exposure poses a serious danger of UV keratitis, especially in places like snowy mountains. The disease can be brought on by just two hours of snow-reflected UV light. An increased sensitivity may result from factors including pupil size, corneal thickness, orbital structure, and the use of photosensitising drugs (such as tetracyclines).

Wearing wide-brimmed hats and UV-blocking sunglasses or contact lenses are examples of preventive measures. The efficiency of sunglasses varies depending on the manufacturing and brands. Wrap-around sunglasses with side shields are suitable for activities in snowy or high-altitude environments, as they can lessen rear reflection and side-entry UV radiation.

One benefit of UV-blocking contact lenses is that they completely cover the pupil and limbus, preventing reflection and side-entry UV rays. The UV filtering capabilities of lenses have greatly improved. However, because of the higher risk of eye infections and the difficulties in maintaining lens hygiene, contact lens use in isolated or harsh situations should be handled carefully.⁷

Summary

Keratitis could develop quickly and severely once we get infected. If we left it untreated, there is a possibility that it would harm our long-term eyesight. However, it is good to bear in mind that keratitis is easily avoidable in many instances. All age groups and behaviours can significantly lower their risk of developing keratitis by regularly practising good eye hygiene and wearing protective eyewear.

The preventative measures are easy to follow, regardless of whether you wear contact lenses, enjoy the outdoors, work in a field that involves chemicals or physical risks, or just value having good eyesight. Though they may seem like little actions, wearing UV-blocking sunglasses, cleaning and replacing contact lenses as instructed, washing your hands before touching your eyes, and using safety goggles when necessary are all effective ways to protect your eyes. It is good to take care of our eyes by starting to change daily hygiene habits.