KERATOCONUS IN YOUNGER PATIENTS

DERMOT MCGRATH REPORTS

Although a general screening for keratoconus in the paediatric population is not warranted, a targeted screening may be indicated in the groups at greatest risk, according to Beatrice E Frueh MD.

“It might make sense to screen certain groups, such as children whose parents or other family members have keratoconus, some ethnic groups, children with Down syndrome, and children with more than two dioptres of astigmatism,” she said.

“Keratoconus is rare in children, but we should be aware young children compensate better for vision loss and may not complain about it,” Dr Frueh explained. “Progression of the disease is much faster in paediatric populations, so early detection is important. Furthermore, we have a viable treatment option in cross-linking, which has shown safe and effective in halting the progression of the disease in paediatric patients.” i Nucci P, Lembo A, Caputo R, Dellavalle A, Serafino M, Schiavetti I, Pichi F, “Efficacy and safety of intraoperative use of tropicamide 0.02%/phenylephrine 0.31%/ lidocaine 1% intracameral combination during pediatric cataract surgery”. Intl Ophthalmol, 2022 Sep 2. doi: 10.1007/s10792-022-02501-4. Epub ahead of print. PMID: 36053475.

Discussing the known risks for keratoconus development, Dr Frueh said surgeons need to consider genetic and ethnic factors.

The reported prevalence of keratoconus in adults is 1 in every 2,000 individuals (0.05%). About 10% of paediatric patients diagnosed with keratoconus have a positive family history of the disease. Some ethnicities are affected more than others, with studies finding a higher incidence of 0.9% to 3.3% among people in Asia and the Middle East. One study from the United Kingdom showed those of Asian origin (Pakistan, India, Bangladesh) living in the English Midlands had a 4.4 higher incidence of keratoconus than the overall population. Another study of 522 patients ranging from 6 to 21 years old in Saudi Arabia found a prevalence of 4.79%.

Studies have found varying frequencies of keratoconus in persons with Down syndrome. A study from Norway drawing on national patient registry data found a prevalence of 5.5% in this subgroup which is around 30 times the estimated keratoconus prevalence in the general Norwegian population. Another recent study in which 98 athletes with Down syndrome attending the 2017 New Zealand Special Olympics National Summer Games were screened found between 30% to 39% had keratoconus, depending on the criteria used.

While screening is a proven means of identifying an unrecognised disease in individuals without signs or symptoms, Dr Frueh said there are some disadvantages associated with its deployment.

“It is time-consuming and expensive to implement, and there is always a risk of overdiagnosis,” she said. “Patients may ignore symptoms later on if the results are normal.”

Summing up, Dr Frueh said there was a convincing case for targeted screening in the population groups she highlighted.

“Retinoscopy is a valid alternative to topography and tomography for screening. We should also remember that screening can be negative in young children, but keratoconus may still develop later,” she concluded.