Introduction
Corneal transplant surgery, also known as corneal grafting or keratoplasty, is a vision restoring procedure where a damaged or diseased cornea is replaced with a healthy donated cornea. During corneal transplant surgery, an ophthalmologist will surgically remove the central portion of the patient’s cornea and replace it with a similarly shaped cornea from a deceased donor. This corneal tissue, obtained from an eye bank, is then sutured into place on the patient’s eye.
Corneal transplant surgery aims to restore vision and reduce pain in individuals suffering from severely impaired eyesight, often caused by conditions such as Fuchs’ dystrophy, keratoconus, infections, or injuries. The procedure has excellent long-term results and over 90% of corneal transplants restore useful vision. However, there are also risks associated with corneal transplant surgery and post-operative care requires life-long use of medicated eye drops to prevent rejection.
In this comprehensive guide, we will discuss when corneal transplant surgery may be needed, how doctors evaluate a patient’s candidacy for a transplant, the different types of corneal transplant techniques, details of the surgical procedure itself, recovery and post-operative care recommendations, risks and complications, and long-term outcomes individuals can expect after corneal transplantation.
When Corneal Transplants Are Needed
Corneal transplant surgery may be recommended when a patient experiences significant visual impairment caused by severe damage or disease affecting the cornea. Some of the most common conditions that can make corneal transplantation necessary include:
• Fuchs’ dystrophy – This condition causes the cells on the inside surface of the cornea (the endothelial cells) to gradually die off, leading to swelling and clouding of the cornea. It typically affects both eyes and causes blurry vision and glare sensitivity.
• Keratoconus – This is a disorder where the normally round cornea progressively thins and becomes cone-shaped. This irregular astigmatism severely distorts vision.
• Corneal scars and opacities – Scars on the cornea from prior injuries, infections, surgery, or chronic eye inflammation can block light transmission and impair vision.
• Corneal swelling (edema) – Various eye diseases can damage the endothelial cells that pump fluid out of the cornea, resulting in corneal edema and blurred sight.
• Corneal dystrophies – These inherited corneal disorders cause deposits or abnormalities to develop in the cornea layers over time.
• Prior corneal graft failure – A small percentage of transplanted corneas eventually fail, requiring another transplant.
In general, when visual acuity falls below 20/40 or better vision cannot be achieved with glasses or contact lenses, corneal transplant surgery may be the best option to help restore sight. Ophthalmologists carefully assess each patient to determine if they are a good candidate before recommending transplantation.
Evaluating Candidacy for Corneal Transplant
Before corneal transplant surgery is scheduled, ophthalmologists will thoroughly evaluate the patient to determine if they are a suitable candidate. Some of the tests and assessments performed can include:
• Slit lamp exam – A slit lamp microscope is used to carefully examine the cornea, anterior chamber, iris, and lens. This allows the surgeon to assess damage and look for any abnormalities that may complicate surgery.
• Corneal mapping – A corneal topographer creates a 3D map of the cornea’s surface, measuring its shape and curvature. This helps plan where surgical incisions will go.
• Corneal pachymetry – This measures the thickness of the cornea, which can indicate if certain procedures are appropriate.
• Eye pressure test – Increased pressure inside the eye (glaucoma) can impact transplant options and recovery.
• Endothelial cell count – Counting the endothelial cells on the inner surface of the cornea helps assess if they are adequate for transplant.
• General health assessment – Medical history, medications, and lab tests to uncover any health issues like diabetes or autoimmune disease that require pre-surgical management.
The ophthalmologist will discuss all treatment options with the patient and help determine if corneal transplantation is the best solution for restoring vision in their particular case. Factors like glaucoma, ocular surface diseases, inflammation, and anterior segment anomalies can impact candidacy. The goal is to set realistic visual outcome expectations for each individual patient.
Types of Corneal Transplants
There are several different techniques and procedures that may be used for corneal transplantation depending on the specific condition being treated:
Penetrating Keratoplasty (PK)
This is the most common and traditional corneal transplant procedure. During PK, the surgeon uses a trephine to remove a full-thickness, circular portion of the central cornea. This includes all corneal layers down to Descemet’s membrane. The donor cornea is then stitched in place using fine sutures. PK replaces the entire thickness of the diseased cornea.
Endothelial Keratoplasty (EK)
Rather than the full cornea, EK replaces only the innermost layer, the endothelium. There are several subtypes of this selective tissue transplant approach:
• Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) – The diseased endothelium is stripped away and an automated microkeratome prepares the donor tissue, which is then implanted.
• Descemet’s Stripping Endothelial Keratoplasty (DSEK) – Similar to DSAEK but the donor tissue is prepared manually.
• Descemet’s Membrane Endothelial Keratoplasty (DMEK) – Only Descemet’s membrane and endothelium from the donor cornea are transplanted.
The EK procedures avoid opening the entire eye and are often used for endothelial disorders like Fuchs’ dystrophy. Recovery time may be shorter compared to PK. The ophthalmologist selects the most appropriate technique based on the clinical indications.
The Transplant Surgery Procedure
The steps involved in the corneal transplant procedure may vary slightly depending on the specific technique being employed, but generally involve:
• Acquiring the donor cornea – The donor tissue is obtained from an eye bank shortly before the procedure. Donor screening rules out communicable diseases.
• Anesthesia – The eye area is numbed using either topical drops or local injectable anesthesia. Sedation may also be provided.
• Protecting the eye – An eyelid speculum holds the lids open and the eye is covered with a plastic drape.
• Removing the damaged cornea – Using a trephine, forceps, scalpel or laser, the diseased central corneal tissue is precisely excised.
• Preparing the donor cornea – Sutures may be pre-placed on the donor tissue. It is shaped to fit into the opening in the patient’s eye.
• Securing the donor cornea – The transplant is positioned and steadily stitched into place using fine nylon or polypropylene sutures.
• Post-op eye shield – A metal or plastic shield is placed over the eye to protect it after surgery.
For partial thickness transplants like DSAEK, only the diseased endothelium is stripped away and replaced with the prepared donor graft. The main goals are to achieve stable wound closure and properly align the donor tissue. Immediately after surgery, antibiotic and anti-inflammatory drops are applied to facilitate recovery.
Recovery Process and Post-Op Care
After the corneal transplant procedure, patients will need to take care to allow their eyes to heal and protect the transplanted tissue:
Hospital Recovery
• Patients are monitored in the recovery room for a couple hours before being discharged.
• The operated eye is kept patched and protected by a metal or plastic shield.
• Oral and topical antibiotics and anti-inflammatory medications are prescribed.
• Discomfort, tearing, light sensitivity, and redness are common initially.
Post-Discharge Care
• Eye drops to prevent infection and rejection are vital for the transplant’s survival and must be taken on schedule.
• Restrictions include no rubbing or pressing on the eye, no swimming or dirty environments. Protective eyewear may be recommended.
• Resting with eyes closed as much as possible for the first few days helps healing.
• Ongoing appointments allow monitoring of pressures within the eye, wound healing, suture stability, visual acuity improvements and medication effectiveness.
Suture Removal
• Absorbable sutures don’t require removal. Non-absorbable sutures are taken out once the transplant is adequately healed, typically 2-3 months post-op.
• This is done by numbing the eye and snip-cutting each suture. It takes several minutes and may cause some temporary blurring.
Vision Improvement Timeline
• Functional vision is possible within a few weeks but continues improving gradually over 6-12 months as swelling resolves and wound healing completes.
• Glasses or contact lenses are usually required for best sight, though amounts vary individually.
Following all post-operative instructions carefully is crucial for ensuring a successful transplant and recovery. Annual eye exams help screen for potential complications after the first year.
Risks and Complications
While corneal transplant surgery is frequently successful in restoring sight, there are also associated risks and potential complications:
• Corneal graft rejection – The recipient’s immune system attacks the donor tissue. Lifelong immunosuppressive eye drops reduce this risk. Signs of rejection include redness, pain and impaired vision.
• Infection – Bacteria or fungi could infect the eye post-surgery. Using antibiotic eye drops prevents most infections. Significant infections may lead to transplant failure.
• Secondary glaucoma – Up to 20% of patients develop increased eye pressure. Additional medications and surgery may be required to treat glaucoma after transplant.
• Cataracts – Around 15-20% of patients develop clouding of the lens within 5 years, requiring cataract extraction surgery. The steroids used long-term tend to increase this risk.
• Retinal detachment – This risk is low, but the retina becoming detached is more likely after full-thickness PK than with endothelial keratoplasty techniques.
• Bleeding (hemorrhage) – Some minor bleeding may occur during the procedure. Serious vitreous hemorrhage is rare.
• Poor vision outcome – A small percentage of patients have suboptimal visual results, with spectacle correction still required. Complete vision loss is very unlikely.
• Transplant failure – In a few cases, the donor cornea never fully adheres or cloudiness redevelops, requiring another transplant.
Patients should weigh the substantial benefits corneal transplants confer in restoring sight against these potential risks and complications. Surgeons help identify any steps that can be taken pre-operatively to reduce individual risk factors.
Long Term Outcomes and Prognosis
With proper surgical technique and rigorous post-operative care, corneal transplants have excellent long-term outcomes:
• Transplant survival rates at 5 years post-surgery are approximately 90% for first-time procedures. Survival gradually declines over time but many last 20-30 years.
• With penetrating keratoplasty, over 90% of patients experience significant visual improvement and restoration of functional vision. More modest improvement is seen in patients with pre-existing glaucoma or ocular surface disease.
• With endothelial keratoplasty, visual acuity generally stabilizes around 20/40 within six months after surgery. Again, improvement may be less dramatic for those with other eye issues.
• Post-transplant vision is often not perfect. Some degree of astigmatism and need for corrective lenses is common. A minority may still require thicker glasses or contacts to see well.
• Lifelong use of anti-rejection eye drops is imperative. Annual exams allow monitoring for late signs of rejection, infection, glaucoma or other complications.
Overall, corneal transplantation has proven to be a highly effective intervention for restoring vision impaired by corneal damage and disease. Close adherence to post-operative care recommendations maximizes the chances of an excellent visual outcome over the long term. For many patients, transplant surgery is life changing, allowing them to regain functional sight.
Conclusion
Corneal transplant surgery has transformed the treatment of many blinding eye diseases that were previously incurable. By replacing diseased corneal tissue with healthy donor tissue, ophthalmologists can restore vision for patients suffering from corneal disorders like Fuchs’ dystrophy, keratoconus, infections, injuries and scarring.
Careful patient selection and evaluation helps ensure transplantation is the best solution and that individuals are good candidates for surgery. There are several surgical techniques available, with the procedure customized based on the particular clinical indications. Penetrating keratoplasty involves full corneal replacement while endothelial keratoplasty replaces only the innermost layer.
The transplant procedure delicately removes the damaged cornea and sutures the donor graft in place. Post-operatively, patients must follow instructions to protect the eye and use special drops to prevent rejection and infection. As recovery progresses over 6-12 months, vision gradually improves. Lifelong follow up is necessary to maintain transplant success.
While there are risks such as rejection, glaucoma and infection, the vast majority of corneal transplants successfully restore functional vision and dramatically improve recipients’ quality of life. This life-changing surgery allows hundreds of thousands of people to regain sight every year. With ongoing advances in technology and techniques, outcomes can be expected to further improve in the future.
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