Keratoconus continues to progress in some older patients

By David Douglas

NEW YORK (Reuters Health) - Although keratoconus is often thought to stop progressing by the time patients are 30 to 40 years old, the corneal degeneration often continues beyond this point, according to researchers from New Zealand.

As Dr. Charles N. J. McGhee told Reuters Health by email, "even relatively mild keratoconus (i.e. correctable with spectacles) may continue to progress beyond age 30 years, with one in three individuals experiencing significant progression in at least one eye."

"This suggests," he added, "that patients with keratoconus over age 30 years should continue to be monitored for disease progression as a subset of these patients may benefit from corneal collagen cross-linking to stabilise the disease."

For their study, online October 28 in the British Journal of Ophthalmology, Dr. McGhee and colleagues at the University of Auckland looked at data for 43 eyes in 27 patients.

Among inclusion criteria were that participants were at least 30 years old, had had at least two consultations a minimum of 12 months apart, did not wear contact lenses (CL) and had no corneal scarring or surgery.

Progression of keratoconus was assessed using quantitative computerized corneal topography. And the investigators point out that by excluding CL users they "avoided the potentially confounding effects of CL wear on corneal shape and possibly the keratoconus disease process."

The subjects' median age at baseline was 38 years and they were followed for a median of more than four years.

Between baseline and final review, there was a significant increase in topographic parameters including maximum keratometry, steep keratometry and flat keratometry. This was also the case for the surface asymmetry index and the surface regularity index.

Between 18.6% and 25.6% of eyes demonstrated a 1.00 D or greater increase in one or more of these parameters. And between 18.5% and 37.0% of subjects had at least a 1.00 D increase in these parameters in at least one eye over the study period.

Fewer than 10% of eyes exhibited a 1.00 D or increase per year in all topographic parameters. Nevertheless, 21% of eyes exhibited a mean increase of 2.73 D in maximum keratometry over the duration of the study. The only significant predictor of progression was follow-up time.

These findings, the researchers conclude, confirm that "keratoconus may continue to progress beyond age 30. Older subjects with keratoconus should be monitored for progression."

Dr. Antonio Curreri, chairman emeritus of the department of ophthalmology at Cabrini Medical Center in New York, told Reuters Health by email that the findings show "that keratoconus does continue to change even after the age of 40, which was previously thought of as the cut-off for progression. The rate of change does slow down considerably. The reason is thought to be that a lifetime of UV exposure (sun) causes cross-linking therefore stabilizing the disease."

"Interestingly," he said, "today's new methods of treating keratoconus are based on the principle of cross-linking the protein within the cornea."

Dr. Curreri added, "to me these results signify that a patient with keratoconus must be monitored and the disease must be thought of when one is making a decision of some kind. For example, in an elderly patient with keratoconus having cataract surgery, the type of intraocular lens may be dictated by this unpredictable disease."

SOURCE: https://bit.ly/2eqd1nF

Br J Ophthalmol 2016.