The Pharmaceutical Journal
Vol 278 No 7446 p402
7 April 2007

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Caution should be exercised when OTC chloramphenicol is being considered

In this case study, Matthew Anderson and Rosalind Harrison remind pharmacists that patients should be assessed appropriately before chloramphenicol eye-drops are prescribed by doctors or sold over the counter by pharmacists

In June 2005 chloramphenicol 0.5 per cent eye drops were reclassified from prescription-only (POM) to pharmacy medicine (P) status.

During the consultation process the Royal College of Ophthalmologists expressed concern about a possible risk to patient safety through misdiagnosis, and further commented that partly treated chlamydial conjunctivitis could lead to a delay in diagnosis of this sexually transmitted infection. The College of Optometrists believes that all patients presenting with a red eye require slit lamp assessment.

Case report

A 20-year-old mason with a three-day history of a red, gritty left eye was referred to our eye casualty department by an on-call GP. The referring GP believed he could not exclude the presence of a foreign body. Three days earlier the patient had been advised over the telephone by his own GP to obtain OTC chloramphenicol eye-drops, which had not brought improvement.

At consultation the patient gave a history of left eye irritation and discharge, and reported left pre-auricular tenderness. He had been grinding at work in the days before the onset of symptoms. He was asymptomatic in the right eye and otherwise healthy.

On examination, erythematous swelling of the left eyelids was noted. A tender left pre-auricular lymph node was palpable. Slit lamp examination excluded a foreign body and revealed follicular conjunctivitis (Figure 1) associated with subconjunctival haemorrhage. Vision was normal. Examination of the right eye was unremarkable.

A diagnosis of presumed adenoviral conjunctivitis was made, and treatment with chloramphenicol eye-drops continued.

At review the patient’s symptoms persisted and he complained of blurred vision in the left eye. Corneal examination revealed multiple subepithelial opacities and punctate staining (Figure 2). His visual acuity dropped to 6/12. A swab for viral culture was negative.

Chlamydial conjunctivitis was then considered, and this was confirmed by a conjunctival swab which tested positive for Chlamydia trachomatis by ELISA (enzyme-linked immunosorbent assay) and direct immunofluorescence. He was treated with topical oxytetracycline and oral doxycycline, and these proved effective.

He was referred to the genitourinary service for appropriate management.

Discussion

The safe use of OTC chloramphenicol eye-drops assumes that checks are in place to prevent sight-threatening conditions from being missed. The Royal Pharmaceutical Society has issued guidance for pharmacists listing signs and symptoms that should be excluded before the medicine is dispensed for treatment of presumed bacterial conjunctivitis.¹

Our patient stated that his own GP and the pharmacist had only asked about eye discharge. He was not asked about the presence of pain, photophobia or contact lens use. The history which should have aroused suspicion of an ocular foreign body and prompted referral was not elicited.

He was not questioned about his visual acuity and this was not formally tested. His eye was inspected by the pharmacist across the counter — no examination light was used. Pupil reactions and eye movements were not assessed.

This case suggests that the recommended referral criteria which should be considered before OTC chloramphenicol is supplied are not being correctly observed. It legitimises the concern that certain patients will be misdiagnosed as having bacterial conjunctivitis.

Chlamydial conjunctivitis is frequently misdiagnosed even by ophthalmology services,² as occurred initially in this instance. Fortunately for this patient the delay in making a diagnosis had no permanent adverse consequences. However, if the intended checks are not heeded before the dispensing of OTC chloramphenicol it is possible that more serious causes of a red eye may be missed, with sight-threatening results.

References

1. Royal Pharmaceutical Society. Practice guidance: OTC chloramphenicol eye drops. London: Royal Pharmaceutical Society of Great Britain; 2006 (PDF 60K)

2. Garland S, Malatt A, Tabrizi S, Grando D, Lees M, Andrew J, et al. Chlamydia trachomatis conjunctivitis. Prevalence and association with genital tract infection. The Medical Journal of Australia 1995;162:363–6.