Contact lens materials and designs such as scleral lenses have greatly improved in the last few decades, and most people with keratoconus can get by with these lenses for improved vision. Keep in mind though that the contact lenses do not stop the continued bulging of the cornea, or progression of the keratoconus – only crosslinking will do that.

Additionally, scleral lenses can lead to hypoxia of the corneal surface when worn too long during the day. As keratoconus progresses and patients become reliant on wearing scleral lenses just to be able to see, it becomes harder to limit wear and patients tend to choose to wear them continuously, jeopardizing the long-term health of their eyes. Early cross-linking treatment to avoid needing rigid contacts is ideal, but scleral lenses are generally still preferable to a cornea transplant.

Penetrating full thickness transplants (PK, PKP), partial thickness deep anterior lamellar transplants (DALK), and tissue addition anterior lamellar transplants (ALKRS, CTAK, CAIRS)

When the keratoconus progresses to the point where vision is not improved enough with contact lenses or someone is unable to successfully wear contact lenses, then corneal transplants become the primary treatment option.

Price Vision Group has published extensively on corneal transplants, and to our knowledge performs more corneal transplants than any other center in the United States. Price Vision Group surgeons are experts in this area and have trained surgeons from around the world. Our doctors routinely give talks on transplants both in the U.S. and internationally.

Most patients with mild or moderate keratoconus can have improved vision with tissue addition surgeries if the central cornea is clear without scarring. Price Vision Group will typically recommend CTAK. The advantages of CTAK or CAIRS (a similar procedure) are that no tissue is removed from the patient’s cornea and nothing is actually transplanted across the central, or visual area of the cornea. A channel is made in the mid portion of the cornea either manually or with a laser. Then a specially shaped portion of donated cornea tissue is inserted into the channel. The insert is custom shaped to the patient’s eye to modify the shape of the patient’s cornea to provide improved vision. The CTAK tissue is processed and treated so there are no viable cells in it. Down time is just a few days at most, and it is done with just topical anesthesia as the cornea can be completely numbed with just eye drops.

We have moved away from using plastic inserts as the tissue addition procedures are more reproducible and now have over 11 years of follow up.

When the cornea is too thin to safely do CTAK or there is central scarring, then we recommend DALK. With DALK we remove all the structural area of the central cornea, the stroma, down to the inner layer called Descemet’s membrane. Leaving Descemet’s membrane and the underlying endothelium greatly reduces the risk of immunologic rejection and allows less use of topical corticosteroids so the graft heals more quickly and securely. The new cornea comes from someone who has died and has donated their cornea. The cornea is fresh as compared to the CTAK corneal grafts, which use preserved tissue. DALK does require sutures to hold the graft in place and the sutures are typically removed 6 to 8 months after surgery. Once sutures are removed then we can determine the degree of visual improvement. About a third of people with DALK continue to wear contact lenses either for treatment of residual irregularities or just so they do not have to wear thick glasses. With DALK, there is always a chance that the recipient’s thin inner corneal membrane may break, which would turn the transplant into a full thickness penetrating keratoplasty (described in more detail below).

With DALK, the thin layer of bulging recipient tissue that is left in place gets compressed by the donor tissue that is added and this can lead in some cases to some folds in the remaining recipient tissue, which can limit visual recovery.  There is always some compression and folding of the tissue, but usually it does not interfere with vision.  If it does interfere with vision, then a partial thickness graft can be done where just the inner layer with folding is replaced with a new thin layer of donor tissue and sutures with a long recovery can be avoided. That is a transplant call DMEK.

Corneal transplants are typically performed using a round blade called a trephine, which is like a small cookie cutter. The trephine is used on the patient’s cornea and on a donated cornea and then the donated cornea is sutured onto the patient’s eye – like changing a window pane in a window.

The cornea is made in layers like plywood, and just like if you cut out a circular area of plywood and glue it back, the transplant wound never heals as strong as the original cornea was. The strength of the wound can be enhanced by using a femtosecond laser to make a zig zag (interlocking) incision on the both the patient’s eye and the donor cornea so the two fit together like a tongue-in-grove in carpentry. We offer this option at Price Vision Group for DALK cases.  This can be especially helpful with keratoconus, because the donor cornea is often thicker than the patient’s cornea it is being sutured into. The zig zag configuration allows better joining of donor and recipient corneas together than a straight vertical cut does, especially when there is a thickness mismatch.

In cases where there is scarring on Descemet’s membrane, especially if there was previous hydrops, then a DALK can be difficult to impossible to achieve.  Then a full thickness transplant is done. As with DALK, sutures are used, but the sutures often remain in place for 12 to 18 months and more corticosteroids are used to prevent immunologic rejection.

Price Vision Group has been actively doing corneal transplants since 1983, and we periodically see patients that we did transplants on 30 or more years ago. For those who had transplants for keratoconus, the recipient or remaining portions of their own cornea sometimes continue to have thinning and bulging outside the grafted area causing astigmatism and distorting the vision. In these cases, if the endothelial layer of the cornea is still functioning and doing well, we can reopen the wound of the transplant in the area of the thinning and resuture it. This maintains the graft which has survived and been tolerated well without rejection for decades. In many cases, the thin areas of the cornea can also be crosslinked to help with healing and minimizing further thinning in the future.