1. Introduction To Corneal Transplantation
Lecture 14
Liana Al-Labadi, O.D.

2. Corneal Transplants
Corneal diseases are the second most prevalent cause of blindness & affect more than 10 million people worldwide according to WHO
The most common treatment for corneal blindness is corneal transplantation with a donor cornea
Corneal Transplant
An operation involving the central part of the cornea
It involves replacing the host cornea with a donor cornea
The operation itself is reasonably straightforward, but the recovery period often takes a long time & optometrists should be able to let their patients know what to expect during and after the surgery

3. Corneal Transplants
As with cataract surgery, primary care optometrists can develop & refine their clinical skills in comanaging patients who undergo corneal transplant surgery
Understanding & mastering preoperative, intraoperative & postoperative components of each procedure, optometrists can develop solid interprofessional relationships with corneal specialists to improve the patient’s overall treatment & ouctcome

4. Corneal Layers Epithelial Layer- 10% of total thickness
Bowman’s membrane- Tough layer
Corneal stroma- Primarily water
Descemet’s membrane- regenerates readily
Endothelial layer- No regeneration

5. Corneal Transplants Two major types of corneal transplants
Penetrating keratoplasty (PK)- full thickness
Affected tissue removed full thickness i.e. all corneal layers
Lamellar Keratoplasty- Anterior or posterior
Indicated when a patient has:
Chronic cornea disorder- vision does not meet the patient’s needs
Patient’s vision cannot be corrected with glasses or contact lenses
Patient cannot tolerate his or her correction
Corneal diseases are the second most prevalent cause of blindness and affect more than 10 million people worldwide, according to the World Health Organization. The most common treatment for corneal blindness is corneal transplantation with a donor cornea. Because of the shortcomings of corneal transplantation, investigators are exploring other alternatives, such as keratoprostheses and tissue engineering. Additionally, they are working to improve upon corneal transplantation by using stem cell transplants and amniotic membranes.
Corneal Transplantation There are several different types of corneal transplant surgery. In corneal graft, or penetrating keratoplasty, the whole cornea—including the epithelium, stroma, and endothelium—is replaced. If the corneal endothelium is diseased, surgeons may opt to perform deep lamellar endothelial keratoplasty (DLEK). This approach works well in patients who have corneal pathology that involves corneal endothelial cells and deep stroma, but whose anterior corneal stroma is clear.

6. Surgical Options Penetrating Keratoplasty (PK)
Deep Anterior Lamellar Keratoplasty (DALK)
Posterior Lamellar Keratoplasty (PLK)
DLEK
DSEK
DSAEK
DMEK
Keratoprostheses

7. Corneal Transplants
1st corneal transplant- performed more than 100 year ago
Corneal transplants at the time involved replacing the entire thickness of the area being transplanted, even when most of the tissue remained healthy
Anterior & posterior lamellar keratoplasty did not become available until the late 90s
Problems with PK surgery
Rejection
High degree of irregular astigmatism
Cataract & glaucoma
PK risks decreased by leaving a portion of the host cornea in place- at least in theory
Pk is indeed a risky procedure
Even more difficult to develop predictable alternatives that provide visual outcomes equivalent to those of PK

8. Corneal Transplants
% of full-thickness corneal transplant procedures continues to decline
In 2008, over one-third of all corneal grafts were endothelial keratoplasties
Less risk of rejection & other complications
Recent development in techniques result in visual outcomes more comparable to those of PK
For those active in corneal surgery comanagement, recent developments may leave them confused
Important to analyze the differences between techniques & outcomes of PK & LK to get a better understanding of deep lamellar surgeries

9. Indications
Indications for corneal transplant may be anatomic or functional
Anatomic indications include:
Visual- opacification, regular refractive error or higher order aberrations (irregular astig)
Reconstructive- thinning or perforation
Therapeutic- edema, dystrophies, degenerations, deposits, intractable infections or painful bullous keratopathy
Cosmetic
Functional Indications
Involve current capabilities, potential capabilities & willingness to risk change
i.e. if an anatomic indication cannot be functionally corrected with medicines or lenses or if the correction cannot be tolerated, a corneal transplant may be warranted

10. PK Indications

11. PK Indications Keratoconus Keratoglobus
Corneal dystrophies: Macualr, granual & fuch’s dystrophy
Glaucoma
Trauma
Infectious
Corneal scarring or corneal edema
Congenital opacity
Corneal perforation
Bullous keratopathy
Failed Graft

12. PK Indications Preoperative consideration
Very important to consider timing of corneal transplant before recommending the surgery
Patients usually experience their best vision 4-8 month postoperatively
Before this time, vision may be worse than before the procedure
Reluctant to recommend surgery on the better eye first or on the fellow eye within six months of the initial procedure
Both eyes rarely require surgery within six months of each other

13. Outcome
Factors that can complicate the outcome of a corneal transplant include:
Poor eyelid anatomy or function
Severe dry eye
Chemical burns- especially alkaline
Previous radiation treatment
The presence of AC or iris-supported IOL
Elevated IOP
Uveitis
Number of previous grafts
Other surgeries- ex: Radiak Keratotomy
Surgeon’s experience

14. Outcome Successful outcome
Significant improvement in the patient’s clinical condition that, in turn, improves his or her overall quality of life
Significant improvement in vision may be two or more smaller lines on an acuity chart
Ability to see with spectacles instead of contact lenses
Restoration of binocularity
Decreased glare
Less pain
Improvement in function & quality of life

15. Outcome

16. Corneal Transplants Donor corneas
Come from someone who has expressed their wish to donate their corneas to help someone see, after their death
The donor’s cornea will have been thoroughly tested & kept in an Eye Bank for a period, before being sent to the hospital where the operation is to be carried out
Eye Bank is responsible for ensuring the donor cornea is in good condition
Eye Bank performs checks to try and ensure cornea is in good condition
Donor corneas should be free from amy infectious diseases
Must be used within 7 days- placed in sterile moist chamber

17. The Procedure Anesthesia
Local block- peribulbar or retrobulbar injection
Used when general health is good
General anesthesia- Used in children
Length of procedure- 1 to 2 hours
During the operation
A circular piece of the host cornea is removed & replaced with a similarly sized piece of the donor’s cornea, which is stitched into place
Other procedures, such as CE, may be done in combination with the corneal graft

18. Sutures are put into the cornea to hold the new graft in place
They affect cornea’s shape & the way the eye focuses
They are not dissolving sutures & will eventually need to be removed
Two main patterns of sutures are used:
Single running suture- left in place for 1-3 years or until spontaneous breakage occurs
Interrupted sutures- used mostly for corneas with peripheral scarring
can be selectively removed from meridians or areas of vascularization after 2-6 months
The Procedure

19. Sutures