Author: Claude, from an owner-approved source list · Reviewed by: Dr Mina Abdelmseih · Reviewed: 2026-11-15 · Review due: 2027-11-15

Educational content only. Not personalised medical advice. Clinical decisions remain the responsibility of the treating clinician.

Geographic Atrophy: Beyond Complement Inhibition

Geographic atrophy (GA) is the progressive, irreversible atrophic form of advanced age-related macular degeneration (AMD) [S1]. Intravitreal complement C3 and C5 inhibitors slow lesion growth but have not been shown to improve visual acuity [S5]. Other approaches (supplements, photobiomodulation, neuroprotection, gene therapy, cell therapy and prostheses) range from modest to experimental [S6] [S7] [S10] [S12] [S13] [S14].

Resource tiers: this is a specialist research topic outside the Tier A / Tier B / Tier C low-resource focus of this library, so no resource tiers are defined here.

Red flags

• Slowing growth is not restoring vision. Complement inhibition likely reduces GA growth but likely does not improve visual acuity at 12 months [S5].
• New neovascular AMD on treatment. Complement inhibition likely increases new-onset neovascular AMD [S5]; in GATHER1 macular neovascularisation occurred in 11.9% and 15.7% of treated eyes vs 2.7% and 2.4% with sham [S3].
• Inflammation with some investigational drugs. The anti-HtrA1 drug galegenimab caused intraocular inflammation in 7.1% of treated patients and its trial was stopped early [S9].
• Promises of "reversal". No therapy in this shortlist reverses established atrophy; the implant and cell approaches are early-stage [S13] [S14].

Recognise it

• GA lesions grow at a pooled mean of 1.66 mm² per year in natural history studies, with larger lesions growing faster [S15].

Confirm it

• Trials measured GA area with fundus autofluorescence [S1] [S3]; colour fundus photographs were used in AREDS analyses [S6].

Manage it

Before acting on this section, check the national and local guidelines, product information and regulatory approvals that apply where you practise. See the medical disclaimer.

Specialist management (retina services)

Complement inhibitors

1. Pegcetacoplan (C3 inhibitor). In OAKS and DERBY (2023), monthly and every-other-month injections slowed lesion growth at 24 months by 22% and 18% vs sham, as reported in the abstract [S1]. In DERBY alone the 12-month reduction was not statistically significant [S1]. In the GALE extension (2025), reductions in growth rate reached up to 32% vs projected sham over up to 36 months [S2].
2. Avacincaptad pegol (C5 inhibitor). GATHER1 (2021) reduced the mean rate of GA growth by about 27% at 12 months [S3]. In GATHER2 (2026), growth from baseline to year 2 was 14% lower with monthly dosing and 19% lower with every-other-month dosing in year 2 [S4].
3. What the pooled evidence says. A living meta-analysis (2024): likely slower growth, likely no gain in visual acuity at 12 months, more ocular adverse events and likely more new neovascular AMD [S5].

Beyond complement inhibition

4. Oral supplements (AREDS formulations). A post hoc analysis of two trials (2025) found slower progression toward the fovea with antioxidants (50.7 vs 72.9 µm per year) and with lutein/zeaxanthin (80.1 vs 114.4 µm per year), but no difference in total lesion area growth [S6].
5. Photobiomodulation. A 2024 meta-analysis of 3 small RCTs (247 eyes, all at high risk of bias) found a statistically significant gain of 1.76 letters that was not clinically meaningful, and no difference in GA area [S7]. LIGHTSITE III (2026) reported a 6.2-letter gain at 21 months and less progression to GA in dry AMD (6.8% vs 24.0%) [S8]. The two conclusions conflict; the evidence is not settled [S7] [S8].
6. Neuroprotection. A brimonidine implant (BEACON, 2023) was stopped early; GA growth at 24 months was 7% lower than sham, not statistically significant [S10].
7. Visual cycle modulators. A Cochrane review (2020) of 3 RCTs (emixustat, fenretinide; 821 participants) found high risk of attrition bias, largely due to ocular adverse effects [S11].
8. Other targets that failed. Galegenimab (anti-HtrA1) did not slow GA growth at 72 weeks [S9].
9. Gene therapy. JNJ-1887 had a manageable safety profile over 24 months in a phase 1 study of 17 patients; efficacy is untested [S12].
10. Cell therapy. A stem-cell-derived RPE implant was safe at a median 3 years of follow-up in 15 implanted patients (phase 1/2a) [S13].
11. Vision restoration for advanced GA. The PRIMA subretinal photovoltaic implant gave a clinically meaningful acuity gain in 26 of 32 participants assessed at 12 months, in a single-arm trial [S14].

Regulatory approval differs by country and is not covered here: check your national regulator.

Refer when

Pitfalls

• Promising better vision from complement inhibitors [S5].
• Missing new neovascular AMD in treated eyes [S3] [S5].
• Overstating photobiomodulation: evidence conflicts [S7] [S8].
• Treating all "beyond complement" agents as promising: several have failed [S9] [S10].

Evidence notes

• GALE compares against a projected sham, not a concurrent control [S2].
• LIGHTSITE III enrolled dry AMD broadly, not only GA [S8].
• Not covered by these sources: cost, injection burden and real-world outcomes of complement inhibitors.

Related articles

• Next-Generation Anti-VEGF and Long-Acting Retinal Drugs
• OCT interpretation: macula and retinal nerve fibre layer
• Low-vision rehabilitation

References

See the numbered source list below. Each marker [S#] links to its PubMed and DOI record.