Autologous corneal transplantation (corneal autograft/autokeratoplasty) is a procedure that replaces a damaged cornea with the patient’s own corneal tissue. It is classified as a special form of penetrating keratoplasty (PKP).
There are two types:
Ipsilateral Rotational Autokeratoplasty (IRA): The cornea of the same eye is excised with a trephine and rotated, moving the opacity to the periphery 1).
Penetrating Bilateral Autokeratoplasty: A healthy cornea from an eye with limited vision (donor eye) is transplanted to the contralateral eye with corneal opacity. The main candidates are functionally monocular patients 2).
The greatest advantage is that there is no risk of allograft rejection 1). However, because the indications are limited and there are abundant alternatives such as oxygen-permeable rigid gas permeable (RGP) contact lenses, scleral lenses, allogeneic corneal transplantation, and artificial corneas (keratoprosthesis), the procedure is performed infrequently.
QWhy is autologous corneal transplantation rarely performed?
A
Although it has the advantage of no risk of rejection, the main reason is that the eligible cases are limited. IRA requires sufficient clear peripheral cornea, and bilateral autologous corneal transplantation requires a healthy contralateral cornea with limited visual potential. Additionally, because various alternatives such as allogeneic corneal transplantation, contact lenses, and artificial corneas exist, it is rarely chosen.
Non-progressive central corneal opacity: Secondary to trauma, post-infectious keratitis, congenital opacity, chemical injury, lipid keratopathy, etc.
Clear peripheral cornea: At least 4–5 mm of clear peripheral cornea must be present.
High risk of rejection: Highly vascularized cornea, history of allograft rejection, children, etc.
Difficulty obtaining donor cornea: Regions with limited access to donor corneas.
Bilateral Autologous Corneal Transplantation
Non-progressive corneal disease: Primary and non-progressive disease localized to the cornea.
Condition of the contralateral eye: The cornea is healthy but visual potential is limited (due to retinal disease, optic nerve disease, amblyopia, etc.).
High risk of rejection: Highly vascularized cornea, history of rejection, children, etc.
Difficulty obtaining donor cornea: Regions with limited access to donor corneas.
Progressive or poorly controlled underlying disease: When the primary disease is active.
IRA: When there is insufficient clear cornea in the periphery.
Bilateral autokeratoplasty: When the contralateral eye (donor eye) has useful vision.
QCan bilateral autokeratoplasty be performed even if the contralateral eye has vision?
A
It is contraindicated when the contralateral eye (donor eye) has useful vision. Since the cornea is removed from the donor eye, only eyes with limited visual potential (e.g., due to retinal disease, optic nerve disease, amblyopia, where visual recovery is not expected) can serve as donors.
The goal is to secure at least 3 mm (ideally 5 mm) of clear cornea in the center to maximize vision. Rotating the opaque area under the upper eyelid also provides cosmetic benefits.
Calculating the size and position of the eccentric trephine incision is complex, and no established guidelines exist. The most commonly cited formula in the literature is as follows:
Dt = 1.5 × Dcl + e (Dt = trephine diameter, Dcl = diameter of the largest area of clear cornea, e = shortest distance from the corneal center to the border between clear and opaque areas)
Afshari et al. proposed a simplified mathematical model with a default eccentric placement of 0.5 mm for an 8 mm graft, which is useful as a guide to balance the removal of opacity from the visual axis and minimization of postoperative corneal thickness mismatch 3). Methods using computer simulation or imaging software to optimize graft size, position, and rotation have also been reported.
In trephination using a femtosecond laser, non-planar patterns such as top-hat, mushroom, and zigzag can be selected. These patterns have a larger wound area and are expected to promote wound healing and allow early suture removal. In particular, the top-hat pattern is advantageous for preserving host corneal endothelium.
Irregular astigmatism: In IRA, it is caused by eccentric incision and mismatch of corneal thickness at the junction, and is the most common postoperative problem.
Wound leak: Caused by suture insufficiency. Check for leakage with a Seidel test.
Glaucoma: Caused by residual viscoelastic material, inflammation, and peripheral anterior synechiae. Postoperative intraocular pressure elevation is seen in about 30% of cases.
Endophthalmitis: Postoperative infection.
Primary endothelial failure: Caused by damage to endothelial cells.
Persistent epithelial defect: Delayed regeneration of corneal epithelium. Patient factors such as dry eye and lagophthalmos are exacerbating factors.
Microbial keratitis: In bilateral autokeratoplasty, there is also risk to the donor eye.
Recurrence of primary disease: When the underlying disease recurs.
QCan rejection occur after autokeratoplasty?
A
In autokeratoplasty, because the patient’s own corneal tissue is used, allograft rejection theoretically does not occur. This is the major difference from allogeneic keratoplasty and is the main advantage of this procedure in high-risk cases for rejection (e.g., highly vascularized cornea, children, history of rejection).
5. Treatment outcomes and postoperative management
Due to limited case numbers, current data are limited to several case series of varying quality. Compared to full-thickness keratoplasty, the following trends have been reported.
Visual improvement: Significant visual improvement and suppression of endothelial cell loss have been shown alone1). Ramappa et al.’s pediatric case series also reported significant postoperative visual improvement4).
Irregular astigmatism: Caused by eccentric trephination, mismatch of corneal thickness at the junction, and proximity of the junction to the pupillary zone. Postoperative astigmatism is significantly higher compared to full-thickness keratoplasty. This irregular astigmatism is the main factor limiting the widespread use of this procedure1).
Treatment outcomes of full-thickness bilateral autokeratoplasty
Sanjuán et al. (Spain, mean follow-up 11.3 years, 31 eyes) analyzed the long-term outcomes of full-thickness autokeratoplasty and reported that 16 eyes (52%) achieved anatomical and functional success, and the most important risk factor for graft failure was progression of pre-existing glaucoma2).
Postoperative management of autokeratoplasty follows that of full-thickness corneal transplantation, except that measures against rejection are unnecessary.
Astigmatism adjustment: Evaluate using mire rings or topography once the corneal epithelium is stable. For interrupted sutures, selectively remove sutures in the steep direction, and repeat adjustments until about 3 months postoperatively. If astigmatism of 5 D or more remains, consider compression sutures or astigmatic keratotomy (AK).
Suture management: Loose or broken sutures can cause infection, so check regularly with fluorescein staining. If abnormalities are found, remove the suture promptly. For continuous sutures, remove the entire suture rather than partial removal.
Intraocular pressure management: In the early postoperative period, residual viscoelastic material and inflammation can easily cause elevated intraocular pressure. Manage with pressure-lowering eye drops, and consider glaucoma surgery if control is poor.
Infection prevention: The cornea is susceptible to infection due to decreased corneal sensation and the presence of sutures. Continue antibiotic eye drops postoperatively.
QWhat is the main cause of graft failure in full-thickness bilateral autologous corneal transplantation?
A
The most important risk factor for graft failure is progression of pre-existing glaucoma2). In the long-term follow-up by Sanjuán et al., glaucoma was observed in 50% of anatomical failures and 77% of functional failures. Postoperative intraocular pressure management is extremely important for long-term graft survival.
