CROSSLINKING BENEFITS

Recent studies suggest that corneal crosslinking (CXL) is safe and can arrest keratoconus progression in children and adolescents for 24 months or more, Farhad Hafezi MD, PhD told the 2014 American Academyof Ophthalmology annual meeting in Chicago. However, these studies also show conflicting results at 36 months. This may be because keratoconus is so aggressive in younger eyes that it may overcome CXL efficacy with time, said Dr Hafezi, Professor of Ophthalmology, University of Geneva, Switzerland and USC Los Angeles, US. But with progression likely in nine of 10 paediatric keratoconus patients, CXL treatment should be considered at initial diagnosis because it can prevent the need for later penetrating or deep lamellar keratoplasty to avoid severe visual impairment, Dr Hafezi said. Young patients also should be followed closely after CXL. Because CXL is so safe in patients with sufficient corneal thickness, retreatment is an option if progression resumes. MUCH HIGHER While the general incidence of paediatric keratoconus ranges from about one in 1,500 in Europe to about one in 500 in the Middle East, risks are much higher in some subpopulations. At somewhere between one in 67 and one in 20, Down Syndrome patients are among the highest risk, Dr Hafezi noted. Yet historically, early keratoconus has been grossly underdiagnosed in Down Syndrome patients, Dr Hafezi said. This may be because sub-par performance on visual acuity tests in this cognitively challenged population is often attributed to poor patient communication or compliance. To raise awareness of the often overlooked risk of keratoconus in Down Syndrome, Dr Hafezi, together with his wife Nikki Hafezi MAS, IP, ETHZ, in 2012 founded Light for Sight 21, so named for the trisomy of chromosome 21 that causes Down’s. “My wife asked me how many Down Syndrome children I had treated with crosslinking, and I said ‘maybe two?’ We started to realise there was a big subgroup that doesn’t get treated.” Nikki Hafezi later expanded the voluntary organisation’s mission to combat preventable blindness from keratoconus for all children and renamed it lightforsight.org. It currently disseminates paediatric and Down Syndrome keratoconus information and develops best practice treatment models. Lightforsight.org also collaborates with referral sites in 25 countries where ophthalmologists can refer patients for keratoconus diagnosis, treatment and check-ups. “We were overwhelmed by the feedback from the [ophthalmic] community. This is a very nice initiative between countries,” Dr Hafezi said. The Evidence Three large studies of the long-term outcomes of CXL for keratoconus in paediatric and adolescent populations have been published in the past two years, Dr Hafezi noted. In his own study, involving 46 eyes in patients aged nine to 19 years treated with CXL and followed from 12 to 36 months, Kmax values and corrected distance visual acuity showed significant improvement at 24 months, but not at 36 months (Chatzis et al. J Refract Surg. 2012 Nov;28(11):753-8). However, a phase II open trial involving 152 keratoconus patients aged 10 to 18 treated with CXL did show significant improvement in Kmax, corneal asymmetry index, and both uncorrected and corrected visual acuity at 36 months (Caporossi A et al. Cornea. 2012 Mar;31(3):227-31). A third study, involving 40 eyes in patients under the age of 18 undergoing CXL, found significantly improved keratometry and uncorrected and corrected visual acuity through 24 months (Vinciguerra et al. Am J Ophthalmol. 2012 Sep;154(3):520-6). As a result, no consensus yet exists on whether crosslinking should be initiated in otherwise eligible paediatric keratoconus patients without waiting for progression, Dr Hafezi said.