Chlamydia Trachomatis Conjunctivitis: A 10-Year Retrospective Of The Incidence, Clinical Presentation, Diagnosis, Management, Outcomes And Epidemiological Trends At A Tertiary Referral Centre In London.

Chlamydia conjunctivitis (or inclusion conjunctivitis), is a sexually transmitted infection (STI) caused by the gram-negative obligate intracellular bacterium Chlamydia trachomatis. C. trachomatis infection is meticulously researched in sexual health literature but there is very limited epidemiology on ocular disease. This work promotes collaborative characterisation of the epidemiology, clinical presentation and spectrum of chlamydia conjunctivitis, informing treatment guidelines and a targeted public health response. 

Chlamydia is the most common bacterial STI in the world. In 2022, Europe saw record-high rates, with 216,508 confirmed cases. In 2023, chlamydia accounted for almost half of all UK STIs; with 194,970 cases in England alone.  Up to 80% of patients with chlamydia conjunctivitis have concurrent genital infection. A concomitant rise in ocular infection is a concern, particularly due to the absence of distinctive clinical features, leading to the underdiagnosis or misdiagnosis of infection.

A 10-year retrospective case series was conducted at a tertiary ophthalmology referral centre in London. Inclusion criteria were laboratory-confirmed Chlamydia trachomatis eye infections (via molecular methods) in any adult (≥18 years) between 1 January 2013 and 31 December 2023. Treatment (in non-pregnant adults) was oral doxycycline 100mg BD 7/7 +/- topical azithromycin 1.5% BD 3/7. Medical records were analysed for clinical presentation, management and complications.

312 cases were recorded, 267 were included. 181(68%) were male, 86(32%) female, mean age was 29 years. Most were unilateral 235(88%) and 32(12%) bilateral. Median time from symptom onset to diagnosis was 14 days. 101(38%) required ≥2 visits before correct diagnosis. Sexual history was absent in 76% and only 4.5% had genital symptoms documented. 93% had no awareness of a genital chlamydia diagnosis. Commonest signs at presentation included conjunctival hyperaemia (95.1%), tarsal follicles (85.4%), mucopurulent discharge (71.5%), punctate erosions (46.1%), tarsal papillae (45.3%), and corneal infiltrates (18.0%). Mean best corrected visual acuity was 0.09 logMAR at baseline. 77.3% recovered to baseline BCVA or better after treatment.

Our study demonstrates that chlamydia conjunctivitis is frequently misdiagnosed in the acute ophthalmic setting, with poor documentation of sexual history and genital symptoms. Ophthalmologists need greater awareness of the incidence and impact of chlamydia. Conjunctivitis may be the only sign of chlamydial infection; diagnosis is critical to prevent serious reproductive consequences and onward transmission. In 2025, new national Chlamydia trachomatis guidelines from the British Association for Sexual Health and HIV (BASHH), will be launched and for the first time, include detailed guidance on the clinical presentation, diagnosis and management of chlamydial eye infection.