Cyclosporine A-Loaded Drug Delivery Systems Show Promise for Reducing Scarring After Glaucoma Surgery

Glaucoma is the leading cause of irreversible blindness worldwide, affecting over 76 million people—with that number projected to hit 111 million by 2040, according to the National Eye Institute. For patients where eye drops or oral medications fail to control intraocular pressure (IOP), surgery is the next line of defense. But here’s a major challenge: up to 50% of glaucoma surgeries fail within five years because scarring clogs the tiny drainage channels created during the procedure. Now, a 2019 study from Fudan University suggests a low-toxicity drug—cyclosporine A (CsA)—could help, especially when delivered slowly through specialized implants.

The Problem: Scarring Sabotages Surgery

When surgeons perform glaucoma surgery (like implanting a glaucoma drainage device, or GDD), they create a “filtering bleb”—a small, fluid-filled blister under the eye’s surface that drains excess fluid to lower IOP. But the body’s natural wound-healing response often backfires: fibroblasts (cells that make collagen) rush to the area, depositing scar tissue that narrows or blocks the drainage channel. Current treatments like mitomycin C (applied once during surgery) help, but they’re not perfect—scarring still plagues many patients.

The Study: CsA-Loaded Implants Target Scarring

Led by researchers from Fudan University’s Eye and ENT Hospital (Shanghai), the study tested two sustained-release drug delivery systems (DDS) loaded with CsA—a drug known for its anti-inflammatory and immune-suppressing effects—on GDDs implanted in rabbits. The goal was to see if slow CsA release could target the 3-month window when scarring is most active.

The team divided 18 rabbit eyes (nine rabbits) into three groups:

Control: GDD with no CsA.
Gel: GDD paired with a PLGA-PEG-PLGA thermogel (a gel that solidifies at body temperature) loaded with CsA.
Coat: GDD coated with PLGA (a biocompatible polymer) that slowly releases CsA.

All procedures followed guidelines from the Association for Research in Vision and Ophthalmology (ARVO) for animal use, and the researcher assessing results was “blinded” (unaware of which group each eye belonged to) to avoid bias.

Key Results: Less Scarring, Better Drainage

Over 12 weeks, the team tracked IOP, bleb appearance, drainage pathway openness, and scar tissue formation. Here’s what they found:

1. Lower IOP (Critical for Saving Vision)

All groups saw IOP drop in the first week post-surgery—but the coat group kept pressure significantly lower than the control group long-term (P < 0.001). The gel group showed a trend toward lower IOP but didn’t reach statistical significance. For context: High IOP is the main driver of optic nerve damage in glaucoma, so sustained pressure control is non-negotiable.

2. Healthier Filtering Blebs

Blebs are the “workhorses” of glaucoma surgery—they need to stay soft, large, and well-vascularized to drain fluid. Using the Indian Bleb Appearance Grading Scale (IBAGS), the team found:

Gel group: Blebs stayed taller and larger than the control group (P < 0.001) thanks to the gel’s "mass effect" (it kept the bleb expanded).
Coat group: Blebs had 30% fewer blood vessels (a sign of less inflammation) than the control group (P = 0.01).

3. Open Drainage Pathways

To visualize drainage, the team injected fluorescent dye into the eye’s anterior chamber. At 4 weeks:

Control group: Only 33% of eyes had open drainage channels—and those channels were narrow.
CsA groups: 100% of eyes had open channels, with larger drainage areas (meaning fluid could flow freely).

4. Less Scar Tissue (The Big Win)

After 12 weeks, the team examined eye tissue under a microscope. The gel and coat groups had 30–50% less scar tissue than the control group. In the control group, scarring had shrunk the blebs—blocking drainage—while CsA-treated eyes kept larger, more functional blebs.

Safety First: No Serious Complications

Importantly, the study found no severe side effects. There were no cases of:

Severe shallow anterior chambers (a dangerous collapse of the eye’s front chamber).
Drainage tube blockages.
Eye infections or GDD exposure.

This is a big deal—safety is non-negotiable for any new treatment, especially for delicate eye surgery.

What Does This Mean for Humans?

While the study was done in rabbits, it provides strong preclinical evidence that sustained CsA delivery could improve glaucoma surgery outcomes. Here’s why it matters:

Timing is Everything: CsA is released over 3 months—exactly when scarring is most active. Mitomycin C, by contrast, is applied once during surgery and wears off quickly.
Targeted Delivery: The gel and coat systems put CsA right where it’s needed (on the GDD or in the bleb), reducing systemic side effects.
Proven Drug: CsA is already used in eye care (e.g., for dry eye) and has a well-understood safety profile.

The Bottom Line

Glaucoma surgery is a lifeline for millions, but scarring has long been its Achilles’ heel. This Fudan University study suggests CsA-loaded DDS could be a game-changer—by slowing scarring, keeping drainage channels open, and preserving vision longer. The coat group’s better IOP control and the gel group’s healthier blebs show that how you deliver CsA matters just as much as the drug itself.

For patients and surgeons, this is hope: a treatment that targets the root cause of surgery failure without serious risks. While more research (including human trials) is needed, this study is a critical step forward in the fight against glaucoma-related blindness.

Original Study Citation

Dai ZX, Song XL, Yu XB, Sun JG, Sun XH. Cyclosporine A-loaded drug delivery systems inhibit scar formation after glaucoma surgery in rabbits. Chinese Medical Journal 2019;132:1381–1384.
doi.org/10.1097/CM9.0000000000000234

The study was funded by the Shanghai Natural Science Foundation (No. 15ZR1405900) and complied with all ethical guidelines for animal research.

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