Glaucoma on Corneal Transplant Prognosis

Patients with pre-existing glaucoma, especially those with drainage devices (valve tubes or Ahmed, Baerveldt, etc.) implants, have a higher risk of complications and worse anatomical/functional outcomes in corneal transplants, whether lamellar (DSAEK/DMEK) or penetrating (PKP).

Problems Associated with Glaucoma and Valved Tubes in Corneal Transplantation

1. Increased Risk of Graft Failure

DSAEK/DMEK:

The presence of a tube in the anterior chamber hinders endothelial graft adhesion, as it:

Interferes with the air/gas bubble used to secure the graft.

Can cause mechanical contact with the graft, leading to its displacement or damage.

Studies show a higher primary graft failure rate (up to 30-40% in eyes with tubes vs. <10% in eyes without glaucoma).

In DMEK, the fragility of the graft makes it especially vulnerable.

PKP:

Although the graft is sutured, persistent corneal edema due to elevated intraocular pressure (IOP) can delay healing.

Increased risk of suture dehiscence if the tube is manipulated.

2. Surgical Technical Difficulty

Positioning the valve tube:

If the tube is too close to the visual axis, it can interfere with the transplant.

In some cases, repositioning the tube is required before corneal surgery (increasing surgical risk).

Reduced anterior chamber space:

Hardens graft insertion and deployment in DSAEK/DMEK.

In PKP, the risk of iris entrapment in the wound increases.

3. Increased Risk of Rejection and Persistent Corneal Edema

Poorly Controlled Glaucoma → Chronic Endothelial Damage:

Elevated IOP reduces donor endothelium survival, accelerating graft failure.

In DMEK, where the endothelium is very thin, the effect is more pronounced.

Immunological Rejection:

Although DSAEK/DMEK has a lower risk of rejection than PKP, in patients with valved tubes, chronic inflammation increases the likelihood of rejection.

4. Complex Postoperative Management

Critical IOP Control:

The air/gas bubble used in DSAEK/DMEK can increase IOP (risk of tube occlusion or optic nerve damage).

Requires frequent monitoring and possibly pressure-relieving maneuvers (paracentesis, medication adjustment).

Use of Steroids:

Necessary to prevent rejection, but can elevate IOP (a dilemma in glaucomatous patients).

Strategies to Improve Prognosis

Aggressive preoperative glaucoma control:

Optimize medication; consider preoperative glaucoma surgery if IOP is uncontrolled.

Surgical modifications:

In DSAEK/DMEK, use alternative insertion techniques (e.g., pull-through with suction cups) to avoid the tube.

In PKP, consider reinforced sutures if there is a risk of dehiscence.

Strict postoperative management:

IOP monitoring for the first 72 hours (risk of spikes due to air bubbles).

Use nonsteroidal immunosuppressants (e.g., topical tacrolimus) to reduce steroid dependence.

Steroid-Induced Glaucoma: A Critical Challenge in Transplant Patients

Steroid-induced glaucoma is a special type of secondary glaucoma that is highly relevant in corneal transplant patients due to the prolonged—and even indefinite—need for treatment with topical or systemic corticosteroids.

Steroids increase the resistance to aqueous humor flow at the trabecular level, causing sustained elevation of IOP.

In transplant patients, this type of glaucoma is particularly difficult to manage, as steroids cannot be easily discontinued without jeopardizing the graft.

The response to treatment with hypotensive drops is often limited, and in many cases, surgical intervention (trabeculectomy or additional valve implantation) is required to preserve the optic nerve and prevent irreversible visual damage.

Therefore, close monitoring of IOP and early identification of patients predisposed to respond to steroids is essential to balance immunological control of the graft and functional preservation of the optic nerve.