9.3 Systemic Medication Retinal Toxicity & Plaquenil Screening
Key Takeaways
- Current AAO guidance recommends hydroxychloroquine dosing of no more than 5.0 mg/kg/day by real weight; for severely obese patients it also advises keeping the dose at or below 400 mg/day.
- Baseline fundus examination, OCT, and fundus autofluorescence should be obtained soon after therapy begins; annual screening with OCT and wide-pattern FAF is recommended while the drug is used, although it may be deferred during the first five years when major risk factors are absent.
- Screen both parafoveal and pericentral patterns. Automated visual fields and multifocal ERG are secondary or confirmatory tests when structural results are uncertain or functional corroboration is needed.
- Retinopathy can progress after hydroxychloroquine stops, especially when RPE damage is advanced, so suspicious results require reproducible confirmation and prompt clinician communication.
- Other systemic medicines can affect the retina or optic pathway; document dose, duration, symptoms, and ordered testing without independently telling a patient to stop medication.
Systemic Medication Retinal Toxicity
Systemic drugs can injure the neurosensory retina, retinal pigment epithelium, optic nerve, or crystalline deposits. The technician gathers an exact medication history, performs ordered tests reproducibly, and routes suspicious findings to the clinician. A technician does not independently discontinue a systemic medicine; the prescribing and eye-care clinicians balance ocular risk against systemic benefit.
Hydroxychloroquine: current 2025 AAO recommendations
The 2025 American Academy of Ophthalmology revision supersedes the older 2016 framework. Recommended hydroxychloroquine dosing remains no more than 5.0 mg/kg/day using real body weight. For a severely obese patient, the revision additionally advises keeping the daily dose at or below 400 mg. Record the actual prescribed dose, real weight, start date, interruptions, renal disease, and concurrent tamoxifen. Do not use an old cumulative-dose threshold as the primary screening trigger.
Major risk factors include a daily dose above recommendation, long duration, renal impairment, and tamoxifen use. Risk increases with exposure duration, but it is not zero early and cannot be decided from duration alone.
Baseline and annual testing
Obtain a baseline fundus examination, spectral-domain OCT, and fundus autofluorescence soon after treatment starts to document preexisting macular disease and provide comparisons. The current primary screening combination is:
- OCT to identify localized photoreceptor, ellipsoid-zone, and outer-retinal change.
- Wide-pattern fundus autofluorescence to reveal parafoveal or pericentral RPE stress and damage.
Annual OCT and FAF screening is recommended while hydroxychloroquine is used. In a patient without significant risk factors, the clinician may defer annual screening during the first five years. This is a risk-based decision, not a blanket rule to wait five years.
Automated visual fields and multifocal ERG are secondary or confirmatory tests. A field can corroborate a functional defect but is subjective and must be checked for fixation and reliability. mfERG can objectively map localized dysfunction when structural results are equivocal. Color plates and Amsler grids are not sufficiently sensitive or specific for hydroxychloroquine screening.
Topographic patterns
Look for both parafoveal and pericentral toxicity in every patient. Older guidance often tied pericentral testing mainly to Asian ancestry. Current guidance emphasizes that either pattern can occur across ancestries. Wide-pattern FAF and appropriate OCT scan coverage help avoid missing disease beyond a narrow central field. If a functional field is ordered, the clinician selects a pattern such as 10-2, 24-2C, or wider testing based on the area at risk and available imaging.
A single questionable scan or noisy field should not trigger irreversible action. Repeat acquisition with correct centration, review prior scans, inspect raw B-scans rather than only a color map, and obtain corroboration as ordered. Once toxicity is convincing, the ophthalmologist communicates with the prescribing clinician. Progression may continue after cessation, particularly when RPE damage is already present.
Other systemic retinal toxicities
| Medication | Important pattern | Technician focus |
|---|---|---|
| Tamoxifen | Crystalline maculopathy, cavitation, or edema | Dose and duration; OCT and acuity as ordered |
| Pentosan polysulfate | Pigmentary maculopathy with dark-adaptation or reading symptoms | Lifetime exposure history; FAF and OCT coverage |
| Thioridazine | Dose-related pigmentary retinopathy | Medication and dose history; color, field, ERG, and imaging as ordered |
| Deferoxamine | RPE change, pigmentary retinopathy, or optic toxicity | Systemic indication, symptoms, and multimodal imaging |
| Vigabatrin | Concentric visual-field loss | Reliable field testing appropriate to age and ability |
| MEK inhibitors | Serous retinopathy-like fluid | Baseline symptoms and OCT comparison |
| Interferon or selected cancer therapies | Cotton-wool spots, hemorrhage, vascular or inflammatory effects | Exact agent, timing, systemic status, and prompt escalation |
Pentosan-associated maculopathy can resemble pattern dystrophy or age-related change. Multimodal imaging and a complete drug history prevent misclassification. Toxicity patterns are not treatment instructions: never advise abrupt cessation, especially when a drug controls autoimmune disease, seizures, cancer, or another serious condition.
Acquisition and documentation checklist
- Verify patient and medication name, daily dose, start date, weight, renal history, concurrent risk medicines, and symptoms.
- Use the ordered scan pattern and confirm that it covers both central and more peripheral macular risk zones.
- Check signal strength, segmentation, centration, fixation, media opacity, and prior-image registration.
- Record the test performed and quality limitations; do not label an artifact as toxicity.
- Promptly route reproducible or concerning change to the interpreting clinician.
- Preserve comparisons and document the handoff.
The safe exam answer distinguishes screening data from clinical diagnosis and uses the current primary tests rather than memorizing superseded rules.
Under the 2025 AAO hydroxychloroquine screening revision, which dosing statement is correct?
Which pair is the current primary testing combination for hydroxychloroquine screening?
A single low-quality OCT appears abnormal in a patient taking hydroxychloroquine. What is the best next step for the technician?