Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a progressive degenerative disease of the macula — the central retina responsible for the sharp, detailed vision needed for reading, driving, and recognizing faces — and is a leading cause of irreversible vision loss in older adults.^[1] AMD exists in two fundamentally different forms that drive completely different management: dry (nonexudative) AMD, characterized by drusen deposition beneath the retina and, in its advanced form, atrophy of the retinal pigment epithelium and photoreceptors (geographic atrophy); and neovascular (wet or exudative) AMD, in which abnormal choroidal blood vessels grow underneath and sometimes into the retina, leak fluid and blood, and cause rapid, severe central vision loss if untreated. Neovascular AMD always arises on a background of pre-existing dry AMD.^[2] Peripheral vision is generally preserved even in advanced disease, so most patients retain independent mobility but lose the fine visual precision needed for reading and detail work. This chapter covers the AREDS2-formulation supplementation that slows progression in appropriately selected dry AMD, intravitreal anti-VEGF therapy as the standard of care for wet AMD, the emerging complement-inhibitor class for geographic atrophy, and the counselling points — smoking cessation, home self-monitoring, and urgent recognition of new visual distortion — where pharmacists have the most direct impact.

Typical presentation

Dry AMD is usually asymptomatic in its early stages and, when it does progress, produces a slow, gradual blurring or dimming of central vision over months to years. Neovascular AMD is different in character and urgency: it typically presents with new or rapidly worsening metamorphopsia (straight lines appearing wavy, bent, or broken), a new central blur or dark spot (scotoma), or a drop in visual acuity over days to weeks rather than months. This difference in tempo matters clinically — rapid-onset distortion should always raise suspicion for neovascular conversion, not simply be assumed to be "worsening AMD."

Several other conditions can cause similar central visual loss and should be kept in mind when a presentation is atypical — pathologic myopia is the most common mimic — but confirming AMD versus an alternative retinal diagnosis is an ophthalmology-imaging task; the pharmacist's role is recognizing when a patient's symptoms warrant referral, not distinguishing between retinal diagnoses.

• Increasing age — the single strongest risk factor; AMD is uncommon before age 55.
• Current or past cigarette smoking — the leading modifiable risk factor.
• Family history of AMD in a first-degree relative.
• Hypertension and cardiovascular disease.
• Light iris and skin pigmentation.
• Obesity, and a diet low in leafy green vegetables and dietary omega-3 fatty acids.
• AMD already present in the fellow eye — the strongest single predictor of future involvement of the other eye.

History

• Character and time course of any vision change — gradual dimming suggests dry AMD progression, while new or rapidly worsening distortion suggests neovascular conversion.
• Specifically ask about central scotoma and metamorphopsia (straight lines appearing curved or crooked) — patients rarely volunteer these terms unprompted.
• AMD in the patient or any first-degree relative.
• Smoking history, current and past.

Physical examination

• Visual acuity.
• Amsler grid testing, one eye at a time.
• Dilated fundus examination with slit-lamp biomicroscopy. Note that the retinal exam alone may be inadequate to exclude a treatable neovascular lesion — imaging is required for a definitive assessment.

Investigations

• Optical coherence tomography (OCT) — noninvasive, widely available, uses infrared light to generate a cross-sectional image of the macula. Considered the gold standard for anti-VEGF treatment decisions, since it directly visualizes retinal fluid.
• OCT angiography (OCT-A) — uses the same machine as OCT to provide additional vascular detail as an adjunct; it does not replace conventional OCT.
• Fluorescein angiography — available only at larger centres and interpreted by retinal specialists; involves an IV injection of fluorescein sodium followed by fundus photography. It is chemically unrelated to iodinated contrast and contains no iodine, so it does not cross-react with an iodine or shellfish allergy, though rare allergic reactions to fluorescein itself can occur. Not a routine first-line test — reserved for cases where OCT findings are ambiguous or a less common lesion type needs characterization.

Several other conditions can produce similar central visual loss and enter the differential — pathologic myopia is the most common — but differentiating these from AMD is a retinal-imaging-based diagnosis made by ophthalmology, not a community pharmacy assessment.^[2]

• Minimize or prevent further vision loss.
• In neovascular AMD, preserve — and where possible improve — central visual acuity through prompt, adequately dosed anti-VEGF therapy.
• In intermediate AMD that meets AREDS2 eligibility, slow progression to late (advanced) disease with daily supplementation.
• Minimize enlargement of geographic atrophy and central scotomas.
• Detect neovascular conversion as early as possible through structured self-monitoring, so treatment can start before irreversible damage accumulates.
• Maintain functional independence and quality of life, including low-vision rehabilitation once vision loss has occurred.

• Assess smoking status at every relevant encounter and offer active cessation support — smoking is the single largest modifiable risk factor for AMD and its progression.
• Encourage a balanced diet with regular leafy green vegetables, which naturally provide lutein and zeaxanthin.
• Teach Amsler grid self-monitoring to every patient with any stage of AMD or a strong family history: use adequate lighting and the patient's usual reading correction, hold or post the grid about 33 cm away, cover one eye at a time, and stare at the centre dot while checking for missing borders, broken lines, or new blur or waviness. Test weekly, and report any new change immediately rather than waiting for the next scheduled visit.
• Refer patients with established vision loss to low-vision rehabilitation services — magnifiers, high-power glasses, reading machines, and low-vision clinics (for example, through the Canadian National Institute for the Blind) can meaningfully restore function for reading and household tasks even when central acuity cannot be recovered.
• Reassure patients that mild eye ache and a small spot of subconjunctival hemorrhage after an intravitreal injection are expected and generally resolve within about two weeks; normal showering and bathing afterward is fine.
• Device-based therapies such as photobiomodulation are under active investigation for non-neovascular AMD but are not yet standard of care or broadly authorized for this indication in Canada.

Breastfeeding

As with pregnancy, breastfeeding intersects with AMD treatment only rarely given the age demographics involved. Systemic absorption of intravitreal anti-VEGF agents is low but not zero, and dedicated lactation data are lacking — an individualized specialist discussion is appropriate rather than a blanket restriction.

Pediatric population

AMD does not occur in children, and this chapter's supplementation and anti-VEGF guidance does not apply to pediatric patients. (Some of the same anti-VEGF agents, notably ranibizumab, do have a separate pediatric indication for retinopathy of prematurity — an unrelated disease process outside the scope of this chapter.)

Renal impairment

Intravitreal anti-VEGF agents require no dose adjustment for renal impairment given their minimal systemic absorption. For AREDS2-formulation supplementation, high-dose vitamin C requires caution in renal disease given a risk of oxalate stone formation, high-dose vitamin E requires caution in renal disease, and high-dose zinc can cause GI upset and, rarely, a severe sideroblastic anemia — review the specific product's doses against these thresholds in a patient with significant renal impairment.

Older adults

AMD is fundamentally a disease of older adults. Screen for fall risk and home-safety concerns once central vision is affected, and reassess driving safety directly rather than assuming a patient will self-report vision changes that affect it.

Iodine allergy

Intravitreal injections are prepped with a topical antiseptic, most often povidone-iodine; ask about iodine allergy before the procedure. A chlorhexidine-based topical antiseptic is an available alternative in Canada when povidone-iodine is not appropriate.

Anticoagulant or antiplatelet use

Subconjunctival hemorrhage after an intravitreal injection is more common in patients taking ASA or anticoagulants; this is not itself a reason to withhold anticoagulation or delay the injection, and the bleeding is benign and self-limited.

For neovascular AMD, monitoring is OCT-driven: visual acuity and OCT are checked at essentially every injection visit to confirm the treatment interval remains appropriate, since persistent or recurrent fluid signals the need to shorten the interval or switch agents rather than continue extending it. Watch for declining response to a previously effective agent (tachyphylaxis) — a meaningful proportion of patients require a switch to a different anti-VEGF agent at some point in their course, and response to switching, including switching back to a previously used agent, cannot be predicted in advance.^[5]

For dry AMD, whether or not the patient is on AREDS2-formulation supplementation, reinforce Amsler grid self-monitoring at every pharmacy encounter and ask specifically about new central blur or distortion — this is the single highest-yield community pharmacy question for this condition, since it is what triggers referral for possible neovascular conversion. Confirm adherence to daily supplementation and screen for unnecessary duplicate zinc, copper, vitamin C, or vitamin E supplements taken alongside a combination AREDS2 product.

After any intravitreal injection, patients should be told explicitly to seek immediate care — not to wait for their next scheduled visit — for severe eye pain, marked new vision loss, redness, or photophobia, which suggest endophthalmitis.^[8]

1. Confirm adherence first: daily AREDS2-formulation supplementation taken as directed, or anti-VEGF injections completed on schedule without missed or excessively delayed doses.
2. For dry AMD that continues to progress despite supplementation, confirm this reflects the expected reality that AREDS2-formulation supplementation slows but does not eliminate progression risk, rather than a red flag — but re-screen specifically for new metamorphopsia or scotoma that would instead indicate neovascular conversion requiring urgent referral.
3. For neovascular AMD with an inadequate anatomic or visual response to the initial anti-VEGF agent despite correct dosing and interval, the standard next step is switching to an alternative anti-VEGF agent — the mechanism of action is similar across agents, an individual patient's response cannot be predicted, and switching (including back to a previously used agent) frequently restores response.
4. For recurrent intraocular inflammation on brolucizumab, discontinue it and switch to an alternative anti-VEGF agent given its class-differentiated inflammation signal.^[9]
5. For advanced geographic atrophy with continued enlargement and no approved pharmacotherapy currently available in Canada, focus on low-vision rehabilitation referral and continued monitoring of the fellow eye — preserving remaining function and catching neovascular conversion early remain the achievable goals.

• Recommending AREDS2-formulation supplementation for early AMD alone, or for a patient with no diagnosed AMD who simply has a family history — neither group was shown to benefit in the trial that established the formulation.^[3]
• Choosing or continuing a beta-carotene-containing vitamin formulation, particularly in a current or former smoker — an equally effective beta-carotene-free (AREDS2) option exists and avoids the added lung cancer risk.
• Missing duplicate supplementation — a patient taking a combination AREDS2 product alongside a separate standalone zinc, copper, vitamin C, or vitamin E supplement risks excess intake without added benefit.
• Reassuring a patient with new metamorphopsia or central blur that it is "just their AMD" without urgent referral — this delay directly worsens visual outcomes, since anti-VEGF benefit is time-sensitive.
• Treating a missed or substantially delayed intravitreal injection appointment as low-stakes — delayed treatment risks disease reactivation and permanent vision loss the same way nonadherence does in any other chronic disease.
• Confusing expected, benign post-injection findings (mild ache, a small subconjunctival hemorrhage) with true red-flag symptoms (severe pain, marked new vision loss, photophobia) — under-triaging risks missing endophthalmitis, and over-triaging causes unnecessary alarm.
• Not asking about smoking status and not offering cessation support at every opportunity, given it is the single largest modifiable risk factor for AMD.

Adult dosing only — AMD does not occur in the pediatric population, so no pediatric dosing line applies to any drug in this table.

Vitamin-Mineral Supplementation (AREDS2 Formulation)

The individual components below make up the evidence-based AREDS2 formulation; most patients take them as a single combination product rather than as separate supplements.

Vascular Endothelial Growth Factor (VEGF) Inhibitors

All agents in this class are given as an intravitreal injection by an ophthalmologist following topical anesthesia and antiseptic preparation (usually povidone-iodine; chlorhexidine is an available alternative). Systemic absorption is minimal, so significant systemic drug interactions are not expected.

Photodynamic Therapy

Emerging Complement Inhibitors for Geographic Atrophy — Not Currently Available in Canada

Both agents target the complement cascade to slow geographic atrophy lesion growth rather than restore vision, and neither is currently authorized for sale in Canada — included here for awareness given active clinical and regulatory interest, not as a prescribable option.