✅ Medically reviewed by Dr Sharon Heng
What is Hydroxychloroquine?
Hydroxychloroquine is a major drug used for treatment and prevention of malaria. It is also used in several autoimmune diseases: rheumatoid arthritis, lupus, and porphyria cutanea tarda, Srojen syndrome. A database study published by King’s college hospital rheumatology department with 3,000 patients estimates that more than 35% of their patients are on this treatment. (1)
Is Hydroxychloroquine Use Harmful to the Eye?
Recent epidemiological data indicate that the prevalence of toxicity amongst long-term (5 years) hydroxychloroquine users is approximately 7.5%. This risk increases to 20-50% after 20 years, depending on individual risk factors. (2) In a separate US study, the prevalence of hydroxychloroquine retinopathy was found to be 0.48% in patients taking a dose of greater than 6.5mg/kg/day. (3)
The Royal College of Ophthalmologists’ guidelines recommended only monitoring after 5 years of treatment, given that only 4% of patients who started hydroxychloroquine continue on it for beyond 5 years.
What are Known Risk Factors for Hydroxychloroquine Retinotoxicity?
Factors associated with higher risks for toxicity including the following:
Patients on chloroquine or high dose hydroxychloroquine (>5mg/kg/day).
Patients with renal disease and impaired renal function (estimated glomerular filtration rate of less than 60ml/min/1.73m2)
Patients on Tamoxifen treatment
What are the Signs of Hydroxychloroquine Retinotoxicity?
Previously, retinopathy was detected after patients developed symptoms by which there would have been considerable irreversible retinal pigment epithelium damage. Clinically, this has been described as a typical parafoveal pattern of RPE loss or a Bull’s eye maculopathy.
This is usually associated with paracentral visual field loss and typically affects both eyes.(4) Further, a korean study have found pericentral damage in patients of Asian ethnicity. (5)Studies have shown continuation of worsening of visual function in patients with RPE damage for approximately 3 years even after cessation of the drug. (4)
How Do We Check or Monitor for Hydroxychloroquine Retinotoxicity?
The advent of a plethora of imaging modality such as spectral domain OCT, widefield color fundus photography and fundus autofluorescence now allows pre-symptomatic detection of RPE damage and modifying or cessation of treatment. Early diagnosis will hence limit the progression of debilitating visual field loss.
The main aim of conducting any monitoring program is not to prevent hydroxychloroquine retinopathy, but to detect the earliest definitive signs of pre-symptomatic toxicity. This will help facilitate the informed decision making process between patients and prescribing physicians on available treatment options as well as the risks and benefits.
Indirectly, this will decrease the proportion of avoidable visual damage in this subgroup of patients.
What is Chloroquine and is it Harmful?
Chloroquine is associated with a higher prevalence of toxic retinopathy when compared to hydroxychloroquine; and is used rarely in clinical practice. Guidance on safe dosing suggests a dose of less than 2.3 milligrams per kilogram per day for chloroquine. Because of the higher risk of retina toxicity, patients should be screened annually.(6, 7)
If you are on hydroxychloroquine or chloroquine, it will be prudent to ensure you have an annual screen with a medical retina specialist.
Ms Sharon Heng is a medical retina specialist and proficient cataract surgeon. She is an expert in retina and macular diseases and has set up the hydroxychloroquine digital monitoring pathway and assessor training modules in Moorfields Eye Hospital city road.
For private consultation, please contact us at info@retina-eye.co.uk
References
Royal College of Ophthalmologists Hydroxychloroquine screening guidelines December 2020
Melles RB, Marmor MF. The risk of toxic retinopathy in patients on long-term hydroxychloroquine therapy. JAMA Ophthalmology. 2014;132(12):1453-60
Levy GD, Munz SJ, Paschal J, Cohen HB, Pince KJ, Peterson T. Incidence of hydroxychloroquine retinopathy in 1,207 patients in a large multicenter outpatient practice. Arthritis and Rheumatism. 1997;40(8):1482-6.
Marmor MF, Hu J. Effect of disease stage on progression of hydroxychloroquine retinopathy. JAMA Ophthalmology. 2014;132(9):1105-12
Lee DH, Melles RB, Joe SG, Lee JY, Kim JG, Lee CK, et al. Pericentral hydroxychloroquine retinopathy in Korean patients. Ophthalmology. 2015;122(6):1252-6
Finbloom DS, Silver K, Newsome DA, Gunkel R. Comparison of hydroxychloroquine and chloroquine use and the development of retinal toxicity. The Journal of Rheumatology. 1985;12(4):692-4.
Rainsford KD, Parke AL, Clifford-Rashotte M, Kean WF. Therapy and pharmacological properties of hydroxychloroquine and chloroquine in treatment of systemic lupus erythematosus, rheumatoid arthritis and related diseases. Inflammopharmacology. 2015.
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