Epikeratophakia is a surgical procedure done to correct large ranges of hyperopia and myopia. It is a type of epikeratoplasty that is performed in aphakic patients. Surgery involves attaching a donated human lenticule to the eye's anterior surface. Due to more significant complications and advancements in modern laser refractive techniques, this procedure is now only occasionally used to correct aphakia in children. Further, it is only considered in children if they cannot undergo lens surgery, do not tolerate contact lenses or glasses, have severe thinning of the cornea, or when other grafting procedures are inappropriate.
Research indicates that epikeratophakia can be an alternative technique in selected keratoconus cases. Epikeratophakia can be used to flatten a cornea that is dilated or distended and eliminate irregular astigmatism. It is considered a less invasive procedure and a safer one because it is an extraocular procedure. Besides, the cryolathed lens does not suffer rejection, unlike in penetrating keratoplasty (PK).
Epikeratophakia carries certain advantages over previous procedures like keratophakia. In epikeratophakia, lenticules can be commercially prepared in a centralized location by a company, leaving the surgeon free to concentrate on the procedure. It is an alternative treatment to aphakic spectacles in both children and adults as well as PK for keratoconus. Epikeratophakia is also a useful technique that can be used to treat corneal thinning or perforation using lamellar corneal patch grafts.
Also Known As
- Epikeratophakic Keratoplasty
Before the Procedure
The ophthalmologist discusses the benefits and risks of the procedure. The patient's medical and ocular history is also taken. Specific measurements conducted via an ultrasonic device will be taken and include:
- Corneal thickness
- The anterior chamber’s depth
- The crystalline lean’s thickness at rest
- The distance between the retina and the lens's posterior surface
Before the procedure, the donor lenticule is prepared. The surgeon needs to provide the average central keratometry readings and spherical equivalent at the corneal plane. The tissue is then lathed accordingly and delivered to the surgeon. The tissue is removed from the vacuum container, and a balanced salt solution containing an antibiotic is used to rehydrate it.
The patient is put under general anesthesia. In the procedure, the surgeon:
- Locates the patient’s optical centre and marks it with a needle or hook. The center is particularly important in patients with myopia
- Removes a part of the central corneal epithelium using a scalpel blade while temporarily leaving intact about 3mm of the corneal epithelium that was centrally marked. The peripheral epithelium is also untouched to help with subsequent postoperative epithelial regeneration
- Performs a partial-thickness trephination, cut in the host cornea
- Performs an annular keratectomy to improve adherence of the epigraft to the host corneal stroma (in keratoconus patients)
- Mechanically removes the residual central host epithelium and any residual epithelial cells, and treats the graft bed with 4% of cocaine or absolute alcohol
- Copiously irrigates the cornea with a balanced salt solution
- Sutures into place the rehydrated epikeratoplasty lenticule
- Administers subconjunctival antibiotics and steroids
- May leave the eye unpadded and not use bandage contact lens
Risks & Complications
Today, epikeratophakia is used in a limited sense because of the limited supply of human donor lenticule. The risks and complications may include:
- Slow epithelial recovery
- Slow post-operative recovery of visual acuity with estimated time said to be 3-6 months to attain 6/6 acuity. Some attain less than 6/6 acuity
- Interface scarring
- Post-operative inflammation
- Reduced distance visual acuity
- Inaccurately cut lenticule in the first place leading to either under correction or over correction
- Sub-optimal final visual acuity because the host cornea remains in situ
- Poor predictable refractive outcome and refractive regression
- Limited vision due to common irregular astigmatism caused by possible distortions that occur when the lenticule is shaped and sutured
- Corneal edema due to endothelial cell loss
- Epikeratophakia performed before increases graft rejection risk in a subsequent PK
Aftercare & Recovery
Patients can go home on the same day. Antibiotic and topical steroid eye drops should be taken three times a day for at least six weeks. In case of complications, the surgeon may opt to increase the topical steroids' dosage from three to six times a day.
Patients are frequently monitored to verify corneal regularity using a Placido disc and tests to check refraction.
If sutures are left in the eye for too long or become loose, they may lead to complications. During follow-up visits, the surgeon may decide to remove a loose suture or remove a suture based on refractive error results, if the suture is contributing to high astigmatism. This action may potentially constitute a risk because the remaining sutures may induce astigmatism. To correct this, the surgeon will have to replace the missing suture, remove the other sutures, then re-insert new sutures. Removal of loose sutures can also lead to hemorrhage into the graft.
Some patients may record increased astigmatism a few months after surgery, necessitating the removal of all sutures. If the astigmatism level keeps increasing, the epikeratophakia lens can be removed, and a PK can be performed to restore vision.
Epikeratophakia improves spectacle-corrected visual acuity in some keratoconus cases.