First Author: E.Ting UK
Co Author(s): J. Ng A. Paul C. Dees D. Vaideanu Collins
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To ascertain the prevalence of macular toxicity in patients on hydroxychloroquine (HCQ) for more than 5 years in a university hospital in the UK and the impact on clinical workload with the aim to develop local screening guidelines.
This is a retrospective study on patients who have been using hydroxychloroquine continuously for at least 5 years under the care of the rheumatology department at James Cook University Hospital, UK.
In 2016, the American Academy of Ophthalmology (AAO) has revised the screening criteria for patients on hydroxychloroquine. The rheumatology department contacted the ophthalmology department to request guidance regarding screening for patients on long term hydroxychloroquine. To assess the impact of screening these patients would have on the ophthalmology department, we have conducted a pilot study. A list of patients who have been on hydroxychloroquine for more than 5 years was identified by the rheumatology department. These patients were contacted to attend a hydroxychloroquine macular screening clinic in the ophthalmology department. Assessment was done based on the criteria set by the AAO guidelines. A full history was taken that included any visual symptoms, the patient’s awareness of potential hydroxychloroquine toxicity, drug history, past medical history and previous ophthalmic history. The duration and dose of hydroxychloroquine was confirmed with the medical records. Snellen visual acuities and Amsler grid test were performed. A 10-2 Humphrey visual fields (HVF) was performed using white targets. This was followed by a dilated fundus examination, Spectral-domain optical coherence tomography(SD OCT), fundus autofluorescence (FAF) and multi-colour photographs.
A total of 156 patients on HCQ were identified by the rheumatologist. 75 patients were invited for screening. Of these, 20 out of 75 patients attended the screening and only 17 out of 20 patients were included in the study. The male to female ratio was 3:14. The median and mean age was 68 (age range 53 -81). The duration of treatment varied between 6-15 years; the median was 7 years and mean was 8.5 years. None of the patients complained of any visual symptoms or were on any other treatment that could cause retinal toxicity. The HVF identified one patient with paracentral scotoma symmetrical in both eyes. This was correlated with subtle changes in the photoreceptor layer on SD OCT. This patient was on HCQ for 15 years and the dose per kg was >5mg/kg (real weight). The patient did not have any visual complaints.
In this small group, only one patient was identified to have visual field defect and SD OCT changes consistent with HCQ toxicity, with no visual complaints yet. However, this patient did not have a baseline HVF or SD OCT to compare with. HCQ retinal toxicity can have devastating effects on patients and therefore it is important that screening is offered to these patients. However, sudden increase in the number of patients referred for screening would have a substantial effect on clinical workload in our department. To manage the workload and also to offer best patient care, based on the results from this small cohort, we have implemented a new pathway for patients on HCQ treatment. A new virtual clinic for screening this cohort of patients has been implemented. The patients will have baseline visual acuities, 10-2 HVF, SD OCT and FAF. The images will be reviewed by an experienced ophthalmologist and appropriate advice given. Also, new patient leaflets explaining visual symptoms caused by HCQ and the importance of screening were designed for use in the rheumatology and dermatology department in our hospital.