Geographic atrophy is the advanced dry form of age-related macular degeneration, in which patches of the retina's light-sensing layer die and expand until they reach the center of vision. Until recently there was nothing to offer. Two approved drugs now exist, pegcetacoplan and avacincaptad pegol, both injected into the eye and both shown to slow the growth of those patches.

The awkward part is what the trials did not show. Across the pivotal studies, the lesions grew more slowly on treatment, and measured visual acuity was largely no different from sham injection. A review published in May concluded exactly that, and it is the central fact anyone considering these drugs needs to hold alongside the approval.

From the Lab to the Ledger

The retina sits on a support layer called the retinal pigment epithelium, which keeps photoreceptors fed and cleared of waste. In geographic atrophy, that support layer and the photoreceptors above it die together in expanding patches. The leading mechanistic explanation implicates the complement system, a branch of innate immunity that tags damaged cells for destruction. Genetic studies have consistently linked complement gene variants to macular degeneration risk, which makes chronic low-grade complement activation a plausible driver of the slow tissue loss.

Both approved drugs dampen that pathway at different points, and both require repeated injections into the eye, roughly monthly to every other month, indefinitely. In the pegcetacoplan trials, lesion growth slowed by something like 16 to 22 percent over two years, with a long-term extension suggesting 20 to 25 percent over three years. Avacincaptad pegol showed reductions in the range of 14 to 30 percent depending on the trial and duration.

Those are real structural effects. The difficulty is that lesion area is a surrogate: it measures the territory lost, not what the patient can read. Standard visual acuity testing uses a high-contrast chart viewed centrally, and in early geographic atrophy the lesions often spare the very center first, so the chart may not register the loss the patient is experiencing. That is one reason a structural benefit can appear without an acuity benefit, and it is also why the measurement question is not settled.

Bio-Pipeline Ledger

Pegcetacoplan: approved and commercially available for geographic atrophy, with 16 to 25 percent reductions in lesion growth across two and three year data. Validated for slowing lesion expansion; functional vision benefit not established in the pivotal trials.

Avacincaptad pegol: approved and available, with lesion growth reductions in the mid teens to about 30 percent depending on trial and timeframe. Same evidence gap on visual function.

AREDS2 supplement formulation: well validated for reducing progression risk in intermediate dry macular degeneration, and not a treatment for established geographic atrophy. Commercially available, with a clearly defined and limited role.

Gene therapy approaches to complement regulation: single-administration therapies intended to make the eye produce its own complement inhibitor, aiming to replace chronic injections. Early clinical stage.

Photoreceptor and retinal pigment epithelium cell replacement: stem cell derived grafts intended to restore lost tissue rather than slow its loss. Early clinical and preclinical, not validated for broad use.

The Clinical Reality Check

What is genuinely available today is a treatment that slows the disease at the tissue level and must be injected into the eye on a continuing schedule. That is a meaningful option for a condition that had none, and for a patient whose atrophy is advancing toward the center of vision, slowing that advance is not an abstract benefit even if a chart cannot yet measure it.

What deserves honest weight on the other side is the safety profile. Both drugs are associated with an increased rate of conversion to the wet, neovascular form of macular degeneration, and there have been rare but serious reports of intraocular inflammation, retinal vasculitis and ischemic optic neuropathy. Any chronic intravitreal injection also carries a small per-injection risk of infection. That is a real cost ledger against a surrogate benefit, which is precisely the kind of trade-off that belongs to a retina specialist and the individual patient rather than to a general rule.

What is overstated is the framing of these drugs as vision-saving. The trials support slowing lesion growth. They do not currently support preserving measured acuity, and the field is actively debating whether better functional endpoints, such as low-luminance acuity or reading speed under dim conditions, would detect a benefit the standard chart misses. The longer extension data and real-world studies are where that question gets answered.

The reasonable posture is attention rather than urgency. Dry macular degeneration progresses over years, which leaves room to get a proper assessment, understand how close the atrophy is to the center of vision, and decide with a specialist whether the trade-off fits. This is a genuine advance with a genuine asterisk, and both halves are worth knowing.