Understanding the spectrum of keratoconus and keratectasia, the causes, risk factors, and treatment remain one of the principal challenges we face in ophthalmology. Population differences in the incidence of keratoconus have long been observed. Genetic and environmental factors have been suspected, however we lack the means of identification and measurement of markers for susceptibility. This search continues. In the meantime, treatment options continue to evolve. The collaborative work of Wilmer Eye Institute and King Khaled Eye Specialist Hospital in Riyadh, Saudi Arabia, is yielding new insights to serve a regional population in need as well as provide guidance for the rest of the world.
John Vukich, M.D.,
| Corneal topography assessment at King Khaled Eye Specialist Hospital Source: Ashley Behrens, M.D.
You may be up to date on all the literature about
keratoconus, but there's much more to be learned in Saudi Arabia
A little more than 2 years ago, the Wilmer Eye
Institute (WEI) at Johns Hopkins, Baltimore, and the King Khaled Eye
Specialist Hospital (KKESH), Riyadh, Saudi Arabia, teamed up to combat eye diseases more quickly than either could working alone. Under the partnership, compelling research and treatment is under way that is leading to superior outcomes for patients with keratoconus. KKESH is a promising center to work on eradicating keratoconus issues. For starters, KKESH is the largest eye hospital in the Kingdom of Saudi Arabia and one of the top-ranked medical facilities in the Middle East. The hospital serves about 1,500 patients per day. Referrals come in from across Saudi Arabia, treated by a team of about 50 ophthalmologists. But beyond KKESH's unique ability, ophthalmologists there are finding it is the perfect place to concentrate on keratoconus studies and solutions. "I have worked in different countries in the past," said Ashley Behrens, M.D., KKESH/WEI professor of international ophthalmology, and executive medical director, KKESH. "I'm originally from Venezuela, and I did most of my training in that country, the U.S., and Germany. I have seen hundreds of patients from these three very different populations, and I have never seen such a high incidence of keratoconus in my clinic."
Keratoconus, an inflammatory, progressive, and ectatic disease of the cornea, is common in Saudi
Arabia and is on the rise, said Samar Al Swailem, M.D., senior consultant, anterior segment division, KKESH. "It is more common than what used to be the case 10 years ago," Dr. Swailem said. "The number one leading cause of corneal transplantation in our population used to be corneal scarring. In the last 10 years, keratoconus has become the number one cause, leading to more than 70% of transplant cases." Dr. Swailem said patients as young as 12 years old are seen to have advanced keratoconus. Research is currently ongoing into this phenomenon, but Dr. Swailem believes genetic and environmental factors are at play. "We believe in our population that more than 10% of keratoconus cases are related to genes," Dr. Swailem said. There is a high rate of consanguinity in Saudi Arabia, which means genetic diseases are common. The high and increasing rate of keratoconus is probably linked to allergy as well, Dr. Swailem said. "We live in a dry and dusty
environment with a high risk of
allergic conjunctivitis," Dr. Swailem said. "This is an important risk
factor for keratoconus." She explained that patients with allergy tend to rub their eyes chronically, and rubbing the cornea is considered one reason for developing ectatic disease. "It makes the cornea softer and reduces the strength of the cornea, causing it to become ectatic instead of preserving its shape," she said. Meanwhile, KKESH is looking into modalities of treatment that would arrest or reduce the progression of keratoconus in the region. Conventional treatments have included contact lenses and keratoplasty. But KKESH is doing research into corneal collagen crosslinking (CXL), which was introduced 3 years ago, and intrastromal corneal rings.
In the process, important lessons have been learned about these new treatment options. "CXL cannot be used in advanced cases," Dr. Swailem said. For safety reasons and so as not to damage the corneal endothelium, patients should have more than 400 microns of corneal thickness—which advanced cases do not have—for CXL to be performed, she said. Nonetheless, it is an important treatment option for other patients. Patient selection, therefore, is critical in treating keratoconus effectively. For patients with advanced keratoconus, KKESH is using intrastromal corneal rings with good success. This modality has been found to be safer in thin corneas. It has been especially useful in Saudi Arabia, where patients have thinner corneas in general, Dr. Swailem said. Currently, the center has more than 7 years of follow-up data on such cases, analyzing results on Intacs (Addition Technology, Des Plaines, Ill.) and the Keraring (Mediphacos Ltda., Brazil). KKESH ophthalmologists have found outcomes to be better with femtosecond implantation of Intacs. "There has been more improvement of uncorrected visual acuity and in best spectacle-corrected visual acuity," Dr. Swailem said. "There also is a higher satisfaction rate among patients, and the infection rate is much less. We believe that the use of femtosecond-assisted implantation of corneal rings in the population over the last 4 years has improved outcomes." Patients implanted as such had less progression of keratoconus and did not need keratoplasty, Dr. Swailem said. KKESH performs a remarkable number of keratoplasties, setting an internal record last January at 206 transplants (Wilmer performs only 380 per year by comparison, Dr. Behrens said). Still, Dr. Swailem looks forward to avoiding more
keratoplasties when possible. "Lamellar keratoplasty started in Saudi Arabia," Dr. Swailem said. "KKESH doctors are skillful in performing deep lamellar keratoplasty. We have good results, but we don't think we need to offer it to moderate or mild cases of keratoconus." She advocates for the use of more intrastromal corneal rings
instead. Although infection has been cited as an uncommon but still occurring complication in some European multicenter and FDA studies, KKESH has experienced fewer infections with intrastromal corneal rings. Dr. Swailem cites use of the femtosecond in lessening infection rates. Shallow implantation is unlikely to occur, she said. The shape of the wound also is smoother and the tunnel is tighter (hence no space for accumulation of foreign bodies). "All of this resulted in reducing infection," Dr. Swailem said. Also of benefit: The procedure allows patients to wear glasses again, the cornea becomes more regular in shape, irregular astigmatism is
reduced, and the procedure is
reversible. Meanwhile, the Wilmer Eye
Institute has benefited from its
partnership with KKESH and vice versa, Dr. Behrens said.
"We never see the amount of keratoconus patients [at Wilmer] that we see here," Dr. Behrens said. "This is something unique. It allows us to do unique research and care for these particular diseases."
Contact lenses, for example, have not been widely used in Saudi Arabia for keratoconus patients. "We use a lot of contact lenses in the Western world [for disease treatment]," Dr. Behrens said. "Here it is very difficult because of the dryness and the dust. However, we are creating a new service of contact lens teaching here. So we dedicate more time to helping patients learn how to wear them, improve their compliance of treatment, and prevent more aggressive treatment." As time goes on, expect to see KKESH publish original research from its findings on keratoconus and new treatments from studies that are currently ongoing. "There is definitely some linkage to keratoconus that is genetic," Dr. Behrens said. "We're trying to detect those factors and genes."
Editors' note: Drs. Behrens and Swailem have no financial interests related to this article.