Autokeratoplasty

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Article initiated by:

Benjamin Park, MD, Tyler Oostra, MD, Vamsee Vemulapalli

All contributors:

Vamsee Vemulapalli, Colleen Halfpenny, M.D., Benjamin Park, MD, Mary Daly, MD

Assigned editor:

Mary Daly, MD

Review:

Assigned status Update Pending

 by Mary Daly, MD on April 22, 2024.

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Contributing Editors:	add

Background

Corneal autograft, or autokeratoplasty, is a relatively uncommon procedure which uses one’s own cornea to replace damaged cornea. There are two types: Ipsilateral Rotational Autokeratoplasty (IRA) and Penetrating Bilateral Autokeratoplasty. In this article we will describe and compare both procedures.

History

Corneal autografts have been a known surgical technique to address corneal opacities for many years. Both IRA and bilateral autokeratoplasty were first recorded within the literature in 1912 and 1908, respectively. Now more than a century later, nearly all aspects of the procedure have been further developed for improved visual acuity, safety, cosmetic appearance, and surgical ease. However, given the limited indications and variety of alternatives such as rigid gas permeable and scleral contact lenses, anterior allogenic lamellar keratoplasty, penetrating allogenic keratoplasty, and keratoprosthesis, corneal autografts are relatively rare procedures.

Indications

Ipsilateral Rotational Autokeratoplasty

• Non-progressive central corneal opacity involving the visual axis. Based on previous literature, this may be secondary to blunt and/or penetrating trauma, postinfectious keratitis, congenital opacities, chemical injuries, or advanced lipid keratopathy.
• At least 4 or 5 mm of clear cornea in periphery.
• Patients with high risk of allogenic graft rejection. This may include those with densely vascularized corneal opacities, previous allogenic graft rejection, or children.
• Patients in areas with poor access to donor material.

Penetrating Bilateral Autokeratoplasty

• Primary, non-progressive corneal disease limited to the cornea.
• Contralateral eye with healthy cornea and limited visual potential (e.g. retinal disease, optic nerve disease, amblyopia).
• Patients with high risk of allogenic graft rejection. This may include those with densely vascularized corneal opacities, previous allogenic graft rejection, or children.
• Patients in areas with poor access to donor material.

Contraindications

• Progressive or uncontrolled underlying disease
• Insufficient clear peripheral cornea for IRA
• Useful vision in the contralateral eye in the case of bilateral autokeratoplasty

Surgical Technique

Ipsilateral Rotational Autokeratoplasty

• 

  Figure 1. Completed ipsilateral rotational autokeratoplasty. Corneal opacities no longer present in the visual axis after surgery. Courtesy of Christine Martinez, MD.
  The goal of this procedure is to achieve 5 mm (minimum 3 mm) of central clear cornea to maximize visual acuity (Fig 1). Additionally, rotation of the opacity below the upper eyelid is desired for maximal cosmetic benefit.
• Optimal Size and Location
  1. Measuring the size and location of trephination is challenging and complex. While several case studies have been reported, there are no clear guidelines to calculate the area of trephination given the rarity of ipsilateral autokeratoplasty.
  2. 

     Figure 2. Trephination planning for ipsilateral rotational autokeratoplasty. Imaged obtained with permission from Srinivas K Rao, MBBS.
     One simplified approach involves a series of 4 marks along the eye. For example, mark the center of the cornea (1), a point 2 mm towards the opacity (2), 1.5 mm from the central mark in the opposite direction, and finally mark a maximal distance toward the limbus (4) (Fig 2). In this case, point 3 is considered the axis of rotation. Exact measurements may depend on the area of opacification and location of clear cornea. Other surgeons have also used more geometric formulae based on digital photographs. Perhaps the most cited formula in the literature is Dt=1.5x Dcl+e (Dt=trephine diameter, Dcl=diameter of largest area of clear cornea, e=shortest distance from center of cornea to the clear-opaque junction). The formula’s ease-of-use and reliability make it a popular choice among surgeons.
  3. A surgeon may also utilize computer simulation and imaging software to optimize the size, location, and rotation of the graft as well as the opacity position.
• After selecting the size and area of the trephine, the following steps should be performed:
  1. The surgeon may mark the trephine area with an RK marker.
  2. The cornea is entered with a paracentesis blade and the anterior chamber is filled with viscoelastic.
  3. The cornea is trephined.
  4. The trephined cornea is rotated.
  5. The final steps consist of suturing the trephined cornea, and are similar to that of Penetrating Keratoplasty.

Penetrating Bilateral Autokeratoplasty

• The surgical steps share many commonalities with penetrating keratoplasty.
  1. Partially trephinate the donor healthy cornea from the eye with limited visual potential.
  2. Carefully remove the healthy corneal autograft with corneoscleral scissors. Take extra care with the tissue, since there is no alternative autograft available.
  3. Cover the donor defect with an eye shield.
  4. Using a similar procedure, trephinate and remove the diseased cornea from the eye with good visual potential.
  5. Suture the healthy autograft onto the eye with good visual potential using 16 interrupted 10-0 monofilament nylon sutures. Complete the procedure using the conventional Penetrating Keratoplasty technique.

Intraoperative Complications

• Irregular trephination
• Trephinating too close to the visual axis for IRA
• Poor graft centration in bilateral autokeratoplasty
• Damage to the iris or lens
• Damage to the autograft
• Choroidal hemorrhage and effusion

Postoperative Complications

• Wound leak
• Glaucoma
• Endophthalmitis
• Primary endothelial failure
• Persistent epithelial defect
• Microbial keratitis. There is additional risk of microbial keratitis in the contralateral eye after penetrating bilateral autokeratoplasty.
• Recurrence of primary disease
• While graft rejection may be a primary concern for penetrating keratoplasty, there is no separate donor in an autograft. Therefore, there is theoretically no risk of graft rejection with autokeratoplasty.

Outcomes

Ipsilateral Rotational Autokeratoplasty

Due to the low surgical volume of IRAs, current data is limited to several case series of widely varying quality. Analysis shows significant improvement in visual acuity in isolation and decreased endothelial cell loss when compared to penetrating keratoplasties (PKs). However, one study also noted significantly lower post-op visual acuity and higher post-op astigmatism when compared to PKs. There are several theories for the increased astigmatism, including eccentric trephination, disparity of corneal thickness at the junction site, and proximity of the junction site to the corneal pupillary zone.

Penetrating Bilateral Autokeratoplasty

Penetrating Bilateral Autokeratoplasty is a rarely performed procedure, given the scarcity of patients with both the specific corneal opacity requirements, and a healthy contralateral cornea with limited visual potential. A Spanish 2020 study by Sanjuán, et al. reviewed 31 eyes of 31 patients receiving penetrating bilateral autokeratoplasty. The cumulative probabilities for anatomic success were 100%, 72%, and 38%, and 77%, 59%, and 29% for functional success at 1, 10, and 40 years, respectively. The most significant risk factor for graft failure was glaucoma, present in 50% of anatomic failures and 77% of functional failures.