Incidence	Cause
Most likely	Bacterial or allergic conjunctivitis
Likely	Viral conjunctivitis, subconjunctival haemorrhage
Unlikely	Episcleritis, scleritis, keratitis, uveitis
Very Unlikely	Acute closed angle glaucoma

Redness of the eye can occur alone or present with accompanying symptoms of pain, discomfort, discharge and loss of visual acuity. Along with an examination of the eye a number of eye specific questions should always be asked of the patient to aid in diagnosis (Table 2.2).

Table 2.2

Specific questions to ask the patient: Red eye

Clinical features of conjunctivitis

The overwhelming majority of patients presenting to the pharmacy with red eye will have some form of conjunctivitis. Each of the three common types of conjunctivitis has similar but varying symptoms. Each presents with the main symptoms of redness, discharge and discomfort. Table 2.3 and Figures 2.2, 2.3 and 2.4 highlight the similarities and differences in the classical presentations of the three conditions.

Table 2.3

Symptoms that help to distinguish between the different types of conjunctivitis

Fig. 2.2 Bacterial conjunctivitis. Reproduced from David A. Palay and Jay H. Krachmer, 2005, Primary Care Ophthalmology, 2nd edition, Elsevier Mosby, with permission.

Fig. 2.3 Viral conjunctivitis. Reproduced from Joseph W Sowka OD, Andrew S Gurwood OD and Alan Kabat OD, Handbook of Ocular Disease Management, Jobson Publishing, with permission.

Fig. 2.4 Allergic conjunctivitis. Reproduced from J H Krachmer, M J Mannis and E J Holland (eds), 2005, Cornea: Volume 1 Fundamentals, Diagnosis and Management, 2nd edition, Elsevier Mosby, with permission.

Subconjunctival haemorrhage: The rupture of a blood vessel under the conjunctiva causes subconjunctival haemorrhage. A segment of, or even the whole eye will appear bright red (Fig. 2.5). It occurs spontaneously but can be precipitated by coughing, straining or lifting. The suddenness of symptoms and the brightness of the blood invariably means patients present very soon after they have noticed the problem. There is no pain and the patient should be reassured that symptoms will resolve in 10 to 14 days without treatment. However, a patient with a history of trauma should be referred to exclude ocular injury.

Fig. 2.5 Subconjunctival haemorrhage. Reproduced from Jack J Kanski, 2007, Clinical Ophthalmology: A Systematic Approach, 6th edition, Butterworth Heinemann, with permission.

Unlikely causes

Episcleritis: The episclera lies just beneath the conjunctiva and adjacent to the sclera. If this becomes inflamed the eye appears red, which is segmental affecting only part of the eye (Fig. 2.6). The condition affects only one eye in the majority of cases and is usually painless or a dull ache might be present. It is more commonly seen in young women and is usually self-limiting resolving in 2 to 3 weeks, but it can take 6 to 8 weeks before symptoms resolve. Episcleritis is one of those conditions, like subconjunctival haemorrhage, that typically looks worse than it is.

Fig. 2.6 Episcleritis. Reproduced from Jack J Kanski, 2007, Clinical Ophthalmology: A Systematic Approach, 6th edition, Butterworth Heinemann, with permission.

Scleritis: Inflammation of the sclera is much less common than episcleritis. It is often associated with autoimmune diseases, for example in 20% of cases the patient has rheumatoid arthritis. It presents similarly to episcleritis but pain is a predominant feature as is blurred vision. Eye movement can worsen pain. Scleritis also tends to affect older people (mean presentation age in the early 50s).

Discharge is rare or absent in both episcleritis and scleritis.

Keratitis (corneal ulcer): Inflammation of the cornea often results from recent trauma (e.g. eye abrasion) or administration of long-term steroid drops. Over wear of soft contact lenses has also been implicated in causing keratitis. Pain, which can be very severe, is a prominent feature. The patient usually complains of photophobia and loss of visual acuity accompanied with a watery discharge. Redness of the eye tends to be worse around the iris. Immediate referral to a medical practitioner is needed as loss of sight is possible if left untreated.

Uveitis (iritis): Uveitis describes inflammation involving the uveal tract (iris, ciliary body and choroids). The likely cause is an antigen-antibody reaction, which can occur as part of a systemic disease such as rheumatoid arthritis or ulcerative colitis. Photophobia and pain are prominent features along with redness and watering of the eye. Usually, only one eye is affected and the redness is often localised to the limbal area (known as the ciliary flush). On examination, the pupil will appear irregular shaped, constricted or fixed (Fig. 2.7). The patient might also complain of impaired reading vision. Immediate referral to a medical practitioner is needed.

Fig. 2.7 Uveitis. Reproduced from Jack J Kanski, 2006, Clinical Diagnosis in Ophthalmology, Elsevier Mosby, with permission.

Very unlikely causes

Acute closed-angle glaucoma: There are two main types of glaucoma:

• simple chronic open-angle glaucoma, which does not cause pain

• acute closed-angle glaucoma, which can present with a painful red eye.

The latter requires immediate referral to the GP or even casualty. It is due to inadequate drainage of aqueous fluid from the anterior chamber of the eye, which results in an increase in intraocular pressure. The onset can be very quick and characteristically occurs in the evening. The eye appears red and may be cloudy (Fig. 2.8). Vision is blurred and the patient might also notice haloes around lights. Vomiting is often experienced due to the rapid rise in intraocular pressure. As it is such a painful condition, patients are unlikely to present to the community pharmacist.

Fig. 2.8 Acute angle glaucoma. Reproduced from Jack J Kanski, 2007, Clinical Ophthalmology: A Systematic Approach, 6th edition, Butterworth Heinemann, with permission.

Figure 2.9 can be used to help differentiation between serious and non-serious red eye conditions.

Trigger points indicative of referral

Red eye

Evidence base for over-the-counter medication

Bacterial conjunctivitis

Bacterial conjunctivitis is regarded as self-limiting – 65% of people will have clinical cure in 2 to 5 days with no treatment – yet antibiotics are routinely given by medical practitioners as they are considered clinically desirable to speed recovery and reduce relapse.

Up until 2005 over-the-counter ocular antibiotics consisted of dibromopropamidine isethionate and propamidine. Both compounds are active against a wide range of organisms, including those responsible for bacterial conjunctivitis. However, clinical trials are lacking to substantiate their effectiveness and a further possible limitation is their licensed dosage regimen (four times a day for drops) has been reported to be too infrequent to achieve sufficient concentrations to kill or stop the growth of the infecting pathogen.

In 2005, chloramphenicol eye drops and in 2007 chloramphenicol ointment were deregulated. Deregulation was probably hindered by case reports linking topical use to cases of aplastic anaemia. However, fears of an association between topical use of chloramphenicol and aplastic anaemia have proven so far to be unfounded. Chloramphenicol has proven efficacy but its routine use has been called in to question.

Rose et al (The Lancet 2005) questioned whether antibiotics were needed in children as no significant difference was seen in the cure rate after 7 days; 86% of the children were clinically cured in the antibiotic group compared with 83% in the placebo group. The authors concluded that antibiotics were not needed in children. The most recent Cochrane review (Sheikh & Hurwitz 2006) concluded that:

although the use of antibiotics is associated with significantly improved rates of clinical and microbiological remission, the benefits are marginal as in most cases the infection is self-limiting. Therefore, when people with clinically diagnosed infective conjunctivitis are treated, the chances that an individual will benefit from treatment is very small.