August
The cornea is the clear, rounded surface at the front of the eye. It helps to focus light and it is meant to be clear and in a regular shape for best vision. If disease, infection, injury, or a genetic issue produces serious cloudiness, puffiness, thin out or distort it routine care may not bring about enough of an improvement.
In some cases an ophthalmologist will put forth the option of corneal transplant. This procedure replaces the damaged section of the cornea with that of healthy donor tissue. Understanding what keratoplasty is, why it may be needed, and how the different types of corneal transplants work can help patients and families approach treatment with greater confidence.
What Is Keratoplasty?
In simple terms, what is keratoplasty refers to surgery that replaces all or selected layers of a damaged cornea. The donor tissue is obtained through an authorised eye bank and carefully assessed before transplantation.
The cornea is made up of many specialized layers. Some diseases affect either the front or the middle tissue in the cornea, while others go after the inner endothelial layer which also is what keeps the cornea clear. Modern keratoplasty types allow surgeons to replace only the unhealthy layer whenever medically appropriate, preserving healthy tissue.
The National Eye Institute explains that a full-thickness transplant may be performed when damage affects the whole cornea, while a partial-thickness procedure may be selected when only certain layers are diseased: https://www.nei.nih.gov/eye-health-information/eye-conditions-and-diseases/corneal-conditions/corneal-transplants.
Who May Need a Corneal Transplant?
A corneal transplant is a treatment which may be looked at when damage is very serious and affects eyesight, causes persistent pain, structurally weakens the eye or is not sufficient to handle it when put in the terms of other eye treatments.
Conditions for transplant include advanced keratoconus, Fuchs endothelial dystrophy, persistent corneal swelling, deep scarring from an infection or injury, inherited corneal dystrophies, severe thinning, corneal perforation, and failure of a previous graft.
A serious corneal ulcer at times causes in depth scarring, out of control infection, progressive thinning, or perforation. But we don’t see transplant as a primary solution for every case of ulcer. In most cases treatment of the cornea ulcer is to control the infection and prevent more damage.
The corneal ulcer treatment cost cannot be estimated accurately without examining the eye. It may also depend on the microorganism involved, diagnostic procedures used, drugs prescribed, length of treatment, inpatient care, and in some cases may require a surgical intervention.
| Corneal condition | Possible effect on the eye | Transplant that may be considered |
| Advanced keratoconus | Progressive thinning, bulging, and distorted vision | DALK or full-thickness transplant in selected cases |
| Fuchs endothelial dystrophy | Corneal swelling and hazy vision | DMEK, DSAEK, or DSEK |
| Deep scar after infection or injury | Reduced transparency and blurred vision | DALK or penetrating keratoplasty |
| Non-healing ulcer or perforation | Tissue loss and structural weakness | Therapeutic or tectonic keratoplasty |
| Failed previous graft | Recurrent clouding and reduced vision | Repeat transplant after detailed evaluation |
What Are the Main Types of Corneal Transplants?
The choice among the different types of corneal transplants depends on which layer is affected, the extent of damage, the health of the remaining tissue, previous operations, inflammation, eye pressure, and the condition of the retina and optic nerve.
Penetrating Keratoplasty
Penetrating keratostrichosis, what is also referred to as PK, is a full thickness cornea transplant. The surgeon removes a circular segment which includes all corneal layers and in its place puts in a similar sized donor tissue which is held in with fine sutures.
Among the established keratoplasty types, PK is a choice when many layers are affected by scarring, disease or structural damage. Recovery and visual stabilization may take longer as the full thickness of the central cornea has been replaced.
Deep Anterior Lamellar Keratoplasty
Deep Anterior Lamellar Keratoplasty also known as DALK which is a procedure that replaces the front and middle layers of the cornea but preserves the patient’s healthy endothelium. It is used for advanced keratoconus, stromal dystrophies and certain scars which have not affected the innermost layer.
Preservation of the patient’s endothelium reduces the chance of endothelial rejection. But DALK is a complex procedure which at times may require conversion to penetrating keratoplasty during the surgery.
Endothelial Keratoplasty
Endothelial keratoplasty is a procedure which replaces the inner layer of the cornea. It is used for conditions in which poor health of the endothelial cells cause fluid to accumulate which in turn causes the cornea to become swollen and cloudy.
DSEK also known as DSAEK is where they transplant a layer of donor endothelial cells with support tissue. DMEK which is a different procedure uses a much thinner graft that includes the donor Descemet membrane and endothelial cells.
These types of corneal transplants generally require fewer or no corneal stitches. An air or gas bubble may be placed inside the eye to support the graft, and the patient may be asked to remain face-up for a specific period after surgery.
Therapeutic or Tectonic Keratoplasty
Therapeutically corneal transplant may be performed for removal of very sick corneal tissue which does not respond to medicine. Tissue grafting of the cornea is used to reinforce or to close a very thin or perforated cornea.
These primary goals of the procedures is to control the disease and preserve eye structure. Visual rehabilitation we address after the eye has stabilized.
| Procedure | Tissue replaced | Common clinical use | Important recovery consideration |
| Penetrating keratoplasty | Full corneal thickness | Multi-layer scarring or severe structural damage | Stitches and visual stabilisation require prolonged monitoring |
| DALK | Front and middle layers | Keratoconus or stromal disease with healthy endothelium | The patient’s healthy inner layer is preserved |
| DSAEK or DSEK | Endothelium with supporting tissue | Endothelial failure and persistent swelling | Positioning may be required for graft attachment |
| DMEK | Descemet membrane and endothelium | Selected endothelial disorders | The thin graft requires careful postoperative monitoring |
| Therapeutic or tectonic graft | Infected, thinned, or perforated area | Uncontrolled infection or structural weakness | Disease control is the immediate priority |
How Is the Right Keratoplasty Type Selected?
Before surgery is recommended the ophthalmologist performs a in depth eye exam. This may include visual acuity test, slit lamp exam, corneal topography or tomography, corneal thickness measurement, endothelial cell study, eye pressure test, and evaluation of the lens, retina and optic nerve.
The surgeon also weighs up whether glasses, specialised contact lenses, corneal cross-linking, medicines, or other eye treatments might still offer enough benefit.
According to the Mayo Clinic corneal transplant is a procedure which is done to restore vision, to bring relief from pain, or to improve a damaged cornea. But results are to also based on what the primary issue is and the health of the eye: https://www.mayoclinic.org/tests-procedures/cornea-transplant/about/pac-20385285.
What Happens During Corneal Transplant Surgery?
In many cases this procedure may be done with local anaesthesia which includes sedation or in some it may be done with general anaesthesia. The eye is numbed, the diseased tissue is removed with care, and the prepared donor tissue is put in.
Full thickness and anterior processes which are common may have fine stitches. For endothelial transplants we see that which is used is an air or gas bubble to hold the donor material at the rear of the cornea.
Many patients go home after surgery which may be after a few days or a week which depends on the type of surgery. In any case a companion is recommended. We also have a tailored surgical approach which includes the type of anesthesia, postural instructions, and drug regimen for each individual patient.
Recovery and Follow-Up Care
Vision post op is usually blurry and improves over time. Recovery is very much a variable thing between different types of corneal transplants. Endothelial procedures may provide for earlier visual improvement than full thickness transplantation, but we don’t have a universal recovery timeline for each patient.
Prescribed antibiotics, steroids, lubricating, or pressure reducing eye drops must be used as directed. Also do not rub or put pressure on the eye, wear the provided protective gear and see us at each follow up.
Strenuous exercise, swimming, driving, heavy lifting, and also dusty environments may be best to avoid at this time. You should go back to these activities only with your ophthalmologist’s approval.
Even out to 6 weeks post surgery glasses or contacts may still be needed. Stitches put in the cornea can cause astigmatism and also pre-existing refractive errors may persist which affects vision.
Risks and Possible Downsides of Corneal Transplantation
Corneal transplant is a well accepted procedure which still is considered major eye surgery. It may present with graft rejection, infection, increased eye pressure, cataract, issues related to sutures, irregular astigmatism, detachment of graft post endothelial surgery, retinal problems, and in some cases graft failure.
Some issues may be addressed if detected early. As for the others we may have to do a second procedure, air bubble reinjection, adjust sutures, treat for glaucoma, or perform a repeat transplant.
Warning signs that require prompt attention include greater redness, eye pain, sensitivity to light, the onset of blurred vision that is sudden or has worsened, and a vague/cloudy appearance in the operated eye. Graft rejection may present even after what seemed to be a stable recovery which is why long term follow up is very important.
Can the Need for a Corneal Transplant Be Prevented?
Not at every turn is it possible to prevent causes of corneal damage which in particular are hereditary dystrophies. But early diagnosis and treatment do play a role in that they may avert some of the more serious outcomes.
Safe care of contact lenses, use of protective eyewear for dangerous work, early treatment of eye infections, routine monitoring of progressive corneal disease, and stay away from unsupervised use of steroid eye drops which may cause damage to the cornea.
Persistent pain, sensitivity to light, discharge, worsening vision, a white spot on the cornea, or any serious eye injury warrants prompt medical evaluation not home remedies or eye drops that were not prescribed.
Conclusion
There is no single corneal transplant suitable for every condition. Understanding what is keratoplasty and comparing the available keratoplasty types helps explain why treatment must be matched to the damaged layer and the overall health of the eye.
Anyone that is having long term corneal issues or is seeing a decline in their vision should see a professional ophthalmologist or go to a reliable eye hospital for a personal exam and discussion of what treatment options are available to you.
Frequently Asked Questions
Possible issues may include an extended recovery time, frequent follow up visits, the need for continued eye drops, astigmatism, rejection, infection, glaucoma, graft detachment or failure. Some patients may still require glasses, contact lenses or further surgery after the graft has healed.
A corneal graft may undergo clear vision for a long time but that is at a variable extent depending on the type of diagnosis, transplant method used, degree of inflammation, presence of glaucoma, prior surgeries, and post op care. Also it is because of late rejection or graft failure which does occur that regular eye check ups are recommended.
During surgery the eye is anesthetized which means that great pain is not to be expected during the procedure. Post procedure mild symptoms of soreness, watering, grittiness, redness or sensitivity may present. Should you experience severe, increasing, or persistent pain it is out of the question to consider that routine and you should seek immediate medical care.
A person may require transplant when severe corneal scarring, swelling, thinning, keratoconus, inherited disease, a non healing ulcer, injury, or a failed graft causes major visual loss, pain, or structural weakness which does not respond to more conservative treatments.
References
- https://www.nei.nih.gov/eye-health-information/eye-conditions-and-diseases/corneal-conditions/corneal-transplants
- https://www.aao.org/eye-health/treatments/about-corneal-transplantation
- https://www.mayoclinic.org/tests-procedures/cornea-transplant/about/pac-20385285
- https://www.ncbi.nlm.nih.gov/books/NBK539690/
- https://www.nhs.uk/tests-and-treatments/cornea-transplant/