Corneal Transplant

Corneal Transplant: Indications, Causes, Care, and Risks

Corneal transplantation (or keratoplasty) is a surgical procedure that replaces a damaged or diseased cornea with healthy donor tissue. It is one of the most successful transplants in medicine, with high success rates when the patient is properly selected and postoperative care is followed.

Main Indications

The transplant is performed when the cornea loses its transparency, shape, or functionality. The most common causes include:

1. Corneal Opacities

Post-infectious scarring (from herpes, bacterial ulcers, or fungi).

Ocular trauma (chemical burns, penetrating wounds).

Corneal edema (endothelial failure, as in Fuchs' dystrophy).

2. Corneal Deformities

Advanced keratoconus (when intracorneal rings or cross-linking are insufficient).

Pellucid marginal degeneration.

3. Other Causes

Congenital diseases (hereditary corneal dystrophies).

Rejection of a previous transplant.

Risks and Complications

1. Graft Rejection

Symptoms: Redness, pain, blurred vision, and photophobia.

Risk factors:

Previous corneal vascularization.

History of rejection.

Inappropriate use of immunosuppressants.

2. Other Complications

Infection (bacterial or fungal keratitis).

Glaucoma (due to postoperative increased intraocular pressure).

Irregular astigmatism (requiring special lenses or additional surgery).

Primary graft failure (in DMEK, if it does not adhere well).

Postoperative Care to Improve Prognosis

1. Medications

Topical corticosteroids (prednisolone) to prevent rejection (sometimes for 1–2 years).

Antibiotics (to prevent infection).

Immunosuppressants (in high-risk cases)

2. Eye Protection

Protective eyewear against knocks or friction.

Avoid swimming or dusty environments for 3–6 months.

3. Periodic Checkups

First week: Monitor graft adherence.

First month: Assess for early signs of rejection.

Every 6–12 months: Long-term monitoring.

4. Lifestyle

Do not rub your eyes.

Use artificial tears if dryness is present.

Control systemic diseases (diabetes, hypertension).

🔹 Prognosis and Success Rates

PKP: 5-year graft survival: 70–90% (depending on the cause).

DMEK/DSAEK: 90–95% success rate in the first year.

Keratoprosthesis: Last option, with a high risk of complications.

Prognosis and Success Rates

Penetrating Keratoplasty (Total Corneal Transplant)

5-year graft survival: 70–90% (depending on the cause).

DMEK/DSAEK

90–95% success rate in the first year.

Keratoprosthesis:

Last option, with a high risk of complications.

Types of Corneal Transplants

Penetrating Keratoplasty (Total Corneal Transplant)

Replacement of the entire cornea.

DALK

Replacement of the anterior layers (preserves the patient's endothelium).

DSAEK/DMEK

Replacement of the endothelium only (for corneal edema).

Keratoprosthesis

Artificial corneal implant (in cases of multiple rejection or complex diseases).

The Importance of Donor Tissue Quality in Corneal Transplantation

The longevity and success of a corneal transplant depend largely on the quality of the donated tissue, as not all corneas are equally viable. Eye banks evaluate multiple factors to ensure a safe and effective graft.

Factors That Determine the Quality of Donated Tissue

1. Donor Age

Optimal: Donors between 18 and 65 years of age.

Corneas from younger donors (≤40 years):

Higher endothelial cell density (essential for corneal transparency).

Lower risk of premature degeneration.

Corneas from older donors (≥70 years):

Possible lower endothelial cell count.

Higher risk of progressive opacity.

2. Endothelial Cell Density

Minimum requirement: 2,000–2,500 cells/mm² (a healthy cornea has ~2,500–3,000).

Evaluation: Pre-transplant specular microscopy.

Low endothelial cells (<2,000/mm²) → Higher risk of post-transplant endothelial failure.

3. Ischemia Time (Preservation)

Safe limit: 7–14 days in a preservation medium (such as Optisol-GS liquid).

More than 14 days: Risk of edema and cell death.

4. Donor Cause of Death

Ideal: Sudden death (e.g., trauma, heart attack).

Should be avoided:

Infectious diseases (HIV, hepatitis B/C, syphilis, active COVID-19).

Neurodegenerative diseases (Creutzfeldt-Jakob disease).

Metastatic cancer (theoretical risk of transmission).

5. Ocular Medical History

Rule out:

Previous surgeries (e.g., LASIK, cataracts).

Corneal diseases (keratoconus, dystrophies).

Ocular trauma.

How is Tissue Preserved and Evaluated?

Extraction: Within 12–24 hours postmortem.

Eye bank evaluation:

Specular microscopy (endothelial count).

Viability tests (turgor, transparency).

Microbiological tests (to rule out infections).

Preservation: In specialized media at 4°C (e.g., Optisol-GS).

Impact on the Recipient Patient

Good tissue:

Faster recovery.

Lower risk of rejection or primary failure.

Suboptimal tissue:

Increased likelihood of corneal edema.

Possible need for retransplantation.

10-0 Nylon Sutures: The Wonder of Ocular Microsurgery

10-0 nylon sutures are one of the finest materials used in ophthalmic surgery, essential for high-precision procedures such as corneal transplants, complex cataract surgery, or ocular trauma repair. Their thinness and strength make them indispensable in microsurgery.

How Small Are They?

Diameter: 20–30 microns (µm).

Comparison:

Human hair: 70–100 µm.

Red blood cell: 7–8 µm.

Needle length: 5–8 mm (almost invisible to the naked eye).

Key Features

Material: Non-absorbable monofilament nylon (polyether).

Strength: Supports delicate tissues without breaking.

Minimizes inflammation: Less tissue reaction vs. silk sutures.

Use in ophthalmology:

Corneal transplantation (penetrating keratoplasty).

Repair of iris or corneal wounds.

Fixation of intraocular lenses (for dislocations).

Suturing of phacoemulsification incisions (cataract surgery).

Sutures in pterygium (carnosity) surgery

Challenges of Use

Microscopic manipulation:

Requires surgical loupes or a microscope.

Needles are so fine they can bend easily.

Precise tying:

Knots must be small and secure to avoid irritation.

Postoperative removal:

In corneal transplants, they are removed between 12 and 18 months.

In cataract surgery, one week after surgery.

In cataract surgery, one week after surgery.

In pterygium (carnosity) surgery, 2-3 weeks after surgery.

Are all patients who need a corneal transplant eligible for corneal transplant surgery?

Corneal transplantation (keratoplasty) is a safe and effective procedure, but not all patients are immediate candidates. The decision depends on ocular, systemic, and surgical risk factors. Here are the key conditions that may limit or delay surgery:

Conditions That May Delay or Prevent Surgery

1. Uncontrolled Eye Diseases

Severe glaucoma: High intraocular pressure damages the optic nerve and compromises the success of the transplant.

Advanced retinopathy (e.g., diabetic or retinal detachment): If the retina is nonfunctional, the transplant will not improve vision.

Extreme dry eye: Risk of postoperative ulcers or infections.

2. Infections or Active Inflammation

Recurrent ocular herpes: Must be inactive for ≥6 months.

Uncontrolled uveitis: Increases the risk of rejection.

3. Problems with Donor Tissue

Corneas with poor endothelial quality (<2,000 cells/mm²).

Recipients with severe corneal vascularization: Higher risk of rejection.

4. Systemic Conditions

Uncontrolled autoimmune diseases (lupus, rheumatoid arthritis).

Decompensated diabetes: Delays healing.

Pregnancy: Postponed until after delivery (except in emergencies).

5. Unrealistic Expectations

If the patient expects "perfect vision" but has other eye diseases (e.g., macular degeneration), the transplant may not meet their expectations.

Alternatives if Not an Immediate Candidate

Specialized contact lenses (for keratoconus or corneal edema).

Keratoprosthesis (artificial cornea): In cases of multiple rejection or complex diseases.

Medical Treatments: For corneal edema (hypertonic solutions).

Transplant success rates exceed 90% in well-selected patients, but preventing rejection requires steroid drops for months or years.

Content Warning

Sensitive Content

Not Recommended for Children

Some cases of Corneal Transplant