Article

CONTACT LENS CASE REPORTS

KERATOPLASTY RATES AND SCLERAL LENS USAGE

Corneal transplant surgery dates back to 1789 when French ophthalmologist Pelliere de Quengsy designed an artificial cornea made of glass. In 1818, German surgeon Franz Reisinger experimented with animal corneas for transplantation. And, in 1838, Irish ophthalmic surgeon Samuel Bigger performed the first successful animal-to-animal transplant. Then, in 1888, German ophthalmologist Eugen von Hipple experimented with human cadaver tissue. In 1905, Austrian ophthalmologist Eduard Zirm performed the first successful corneal transplant surgery in a human. Further keratoplasty advances were made in the 1930s by Vladimir Filatov of Russia and by Ramon Castroviejo and Max Fine in the United States.

Past and Present

Early human corneal transplant surgeries were square in shape and often failed due to tissue rejection, graft dehiscence, and glaucoma. Figure 1 shows a surviving corneal transplant (40 years postoperatively) performed by Max Fine in the 1940s.

Figure 1. A surviving square corneal transplant performed by Dr. Max Fine in the 1940s.

Today’s corneal transplant surgery success rates have dramatically improved due, in part, to the culmination of advancing technologies that include improved eye banking techniques for corneal preservation, surgical techniques, and instruments as well as pharmacologic advances in topical steroids and antibiotics.

Eye Bank data show that, in the United States, the indications for keratoplasty procedures utilize approximately 73,000 corneas per year for penetrating keratoplasty, anterior lamellar keratoplasty (ALK), and endothelial keratoplasty. Since 2011, if no specific keratoplasty diagnosis is noted on forms returned to eye banks, the diagnosis is considered “unknown.” Those “unknowns” potentially skew the data, because the diagnosis is missing for 31% of all grafts (www.restoresight.org ).

At Pacific University, we have noted a significant decrease in the number of keratoconus patients being referred for keratoplasty due to contact lens intolerance. The primary reason for this observation has been the advent and increasing popularity of scleral lenses since 2011. Practitioners can see this trend reflected in the U.S. Eye Banking data from 2004 to 2016 (Figure 2).

Figure 2. Eye Bank data for keratoplasties for keratoconus from 2004 to 2016.

Overseas, clinicians often attribute the decline in keratoplasties for corneal ectasias to the long-standing availability of corneal cross-linking (CXL). However, in the Untied States, CXL techniques were not approved by the U.S. Food and Drug Administration until April 2016. Therefore, it is unlikely that CXL played any role in that decreasing number.

In Conclusion

It is clear that modern scleral lenses have had a dramatic impact on how corneal ectasias are managed. Therefore, practitioners must now refocus their efforts to better understand the potential negative effects of these lenses, such as long-term conjunctival prolapse and increased intraocular pressure changes when wearing scleral lenses. For many, scleral lens wear is a “one-way ticket,” and there is no going back to traditional contact lens designs. CLS