Introduction

The term keratoconjunctivitis describes a group of conditions affecting the cornea and conjunctiva, presenting significant challenges in clinical practice due to their diverse causes and manifestations. They may even threaten vision if left untreated. Various causes contribute to this ocular condition, including viral (especially adenoviruses), bacterial, autoimmune, toxic, and allergic factors. Additionally, dry eye-related keratoconjunctivitis, resulting from tear film instability, plays a significant role. Autoimmune conditions like Sjögren’s syndrome can further complicate the disease by damaging the ocular surface and worsening symptoms. Keratoconjunctivitis symptoms range from mild irritation to severe and vision-threatening inflammation, making a timely and accurate diagnosis essential for effective treatment.^1,2

The prevalence of keratoconjunctivitis varies according to the subtype and location. As an example, viral keratoconjunctivitis often occurs as outbreaks, especially in crowded environments like schools and workplaces. In contrast, dry eye-related keratoconjunctivitis tends to affect older people, particularly people assigned female at birth (AFAB) who have gone through menopause.¹

Keratoconjunctivitis patients typically experience several common symptoms, including eye redness, photophobia, blurred vision, excessive tearing, and a gritty or foreign body sensation. In severe cases, symptoms may include a sharp pain in the eye, thick or pus-like discharge, and difficulty keeping the eye open due to irritation. A physician may observe signs such as red and swollen conjunctivae (conjunctival hyperemia), corneal damage, swelling of the eyelids, or small bumps on the inner surface of the eyelids (papillae). In addition to these clinical findings, a patient's medical history assists in distinguishing between different types of keratoconjunctivitis.³

Symptoms

In keratoconjunctivitis, symptoms vary depending on the type. Virus-induced keratoconjunctivitis usually affects one eye first, then spreads to the other. An inflammation of the conjunctiva, discomfort or itchiness, light sensitivity, and watery discharge can be symptomatic. It's common for patients to experience upper respiratory illnesses and swollen lymph nodes. Symptoms can last between 7 and 21 days, and affected individuals remain contagious for 10 to 14 days.⁴ 

It is important to carefully examine several symptoms of suspected keratoconjunctivitis when evaluating a patient with this condition.⁴

• Ocular discomfort: patients often describe a burning, gritty feeling or the sensation of a foreign body in their eye
  • A common symptom of dry eye disease
• Redness: usually indicates conjunctival inflammation in keratoconjunctivitis (hyperemia)
• Tearing: ocular irritation or dryness may trigger reflex tearing
• Itching: a prominent symptom of allergic keratoconjunctivitis, including vernal and atopic forms
• Photophobia: the perception of light may indicate corneal involvement, generally associated with epithelial damage or keratitis
• Blurred vision: may result from tear film instability, irregularities of the corneal surface, or scarring in the stromal layer
• Discharge: viral discharge is typically watery, while bacterial discharge is thick, mucopurulent

Vernal keratoconjunctivitis 

An individual with vernal keratoconjunctivitis will experience itching, sensations of foreign bodies in their eyes, light sensitivity, mucus discharge, and inflammation of the conjunctiva. There is a wide range of severity in these symptoms, which can disrupt daily activities. Pin-sized epithelial erosion on the cornea and keratitis are signs of this condition. Moreover, during winter, patients are more likely to experience episodes.⁴

Keratoconjunctivitis sicca

Keratoconjunctivitis sicca or dry eye disease is characterised by chronic but often intermittent symptoms such as:⁴

• Burning
• Stinging
• Foreign body sensation
• Light sensitivity
• Fatigue
• Heavy eyelids
• Itching
• Excessive tearing
• Watery discharge
• Blurred vision

It is common for these symptoms to worsen when you are reading, using a computer, or driving when your natural blink reflex is impaired.⁴

Superior limbic keratoconjunctivitis

The symptoms of superior limbic keratoconjunctivitis include burning, irritation, and a sense of a foreign body in the eye. There are usually chronic symptoms with gradual clearing, but there can also be periods of remission. Furthermore, the disease can cause conjunctival overgrowth (pannus) on the cornea, depending on its severity and duration.⁴

Management and treatment

It is important to determine the cause of keratoconjunctivitis to manage it, as treatment strategies differ depending on the cause.

Epidemic keratoconjunctivitis

Epidemic keratoconjunctivitis (EKC) is highly contagious due to its viral origin, usually adenovirus. Infection control is therefore paramount. Direct contact with contaminated hands, shared household items, or inadequately disinfected medical equipment is the most common method of transmission. To limit the spread of the disease, household and clinical surfaces must be regularly disinfected.⁵ 

Incubation lasts for 5 to 12 days, and patients remain infectious for up to 14 days after exposure. A patient's and caregiver's understanding of the disease's prolonged course is important for managing expectations and avoiding unnecessary follow-up visits.⁵ 

Aside from supportive therapies, such as artificial tears, cold compresses, and topical antihistamines, epidemic keratoconjunctivitis does not have a definitive treatment. Additionally, topical ganciclovir or cidofovir may have therapeutic potential in in vitro studies.⁶

Vernal keratoconjunctivitis

It is common for vernal keratoconjunctivitis (VKC) to require a multidisciplinary approach, and consulting an ophthalmologist is usually recommended. Management aims to relieve symptoms and minimise treatment-related adverse effects. 

Lubricants, such as preservative-free artificial tears, gels, and ointments, are the first line of therapy but may not suffice on their own. Allergen exposure can be reduced by adjunctive measures such as cool compresses and lid hygiene. 

• In mild cases, topical antihistamines may be sufficient to relieve symptoms 
• In moderate cases, mast cell stabilisers like cromolyn sodium, nedocromil sodium, and lodoxamide are commonly added to antihistamines 

However, antihistamines require a loading period before they become effective. It may be helpful to initiate the treatment before symptoms arise for patients with seasonal symptoms in order to prevent flare-ups. The antihistamine and mast cell-stabilising properties of combination products, such as olopatadine, azelastine, and ketotifen, are present in these medications. 

Systemic antihistamines can be considered, but their use is limited by their potential side effects. NSAIDs may be used topically, but they are often ineffective. In contrast, topical corticosteroids are usually the most effective option, especially when used at high doses and rapidly tapered. Despite minimal systemic side effects, intraocular pressure (IOP) should be closely monitored. A steroid-sparing modulator like cyclosporine or tacrolimus can be used to effectively control chronic or severe symptoms.^7,8,9

Keratoconjunctivitis sicca

Keratoconjunctivitis sicca, or dry eye disease, is usually managed conservatively. The ocular surface is lubricated with artificial tears, gels, and ointments that contain no preservatives. It is possible to contribute to tear film stability by warming the meibomian glands and practising lid hygiene. There is also evidence that nutritional supplements like flaxseed and fish oil can alleviate symptoms and reduce the need for topical treatments. 

Symptoms can be managed with procedural interventions such as punctal plugs and cautery, which are more permanent solutions. A number of prescription therapies are available that are steroid-free, including topical cyclosporine A, tacrolimus, and lifitegrast. The use of topical corticosteroids should also be limited to short courses with close monitoring of intraocular pressure. Due to its anti-inflammatory properties, low-dose oral doxycycline may be an effective treatment option. Topical autologous serum eye drops, rich in anti-inflammatory factors, have emerged as a promising treatment in recent years, though their high cost remains a limitation. It is often necessary to combine therapies to provide adequate and sustained symptom relief.¹ 

Superior limbic keratoconjunctivitis

Superior limbic keratoconjunctivitis is generally treated conservatively initially, using preservative-free artificial tears, gels, and ointments. A variety of topical therapies may be tried with variable results, including mast cell stabilisers, antihistamines, vitamin A, and NSAIDs. Ocular surface moisture can also be improved by punctal occlusion. Although autologous serum eye drops have demonstrated efficacy, long-term use is often necessary, and costs can be prohibitive. Short-term relief can be obtained from silver nitrate chemocautery of the superior conjunctiva. However, a repeat procedure is often necessary. 

In recurrent cases, surgical resection of the affected conjunctiva may be preferable. In addition to liquid nitrogen cryotherapy, repeated sessions may be necessary.^10,11,12

Summary

Keratoconjunctivitis refers to inflammation of the cornea and conjunctiva, which is caused by a number of factors such as viruses, allergens, autoimmune diseases, or dry eyes. A proper diagnosis is essential for treating symptoms such as redness, irritation, tearing, and blurred vision. In spite of the lack of specific antiviral treatments, epidemic keratoconjunctivitis is a highly contagious viral infection managed through hygiene and supportive care.

There are several treatments for vernal keratoconjunctivitis, including lubricants, antihistamines, mast cell stabilisers, and corticosteroids in cases of severe symptoms. Symptoms of keratoconjunctivitis sicca are treated with preservative-free tears, warm compresses, supplements, and anti-inflammatory drops, with advanced cases requiring punctal plugs or serum drops. There is no cure for superior limbic keratoconjunctivitis, and the condition is treated conservatively with lubricants. It may require surgical procedures such as silver nitrate application or eye drops to relieve symptoms.