Carneiro de Freitas MD
Intrastromal corneal ring segments (ICRSs) can provide good visual results in patients less than 20 years old, with good stability and visual recovery in the longer-term, a recent study suggests.
“There are many different approaches towards keratoconus, depending on the potential of progression, refractive status and corneal profile and thickness, with the main goals being to correct the corneal ectasia, restore the regular prolate shape of the cornea, improve the associated refractive error and higher-order aberrations, and ultimately stop or at least slow the ectasia progression,” said Rui Carneiro de Freitas MD, speaking at the XXXIV Congress of the ESCRS in Copenhagen, Denmark.
The ICRS is one of several treatment options, but more data is required for specific patient populations. Despite recent publications with long-term follow-up showing the stability of the results up to 10 years in terms of keratometry and visual acuity (VA) in older patients, there is a paucity of data regarding ICRSs in younger patients, noted Dr Carneiro de Freitas, Hospital de Braga, Portugal.
In order to correct this knowledge gap regarding young patients, Dr Carneiro de Freitas’s team, led by Dr Tiago Monteiro, performed a retrospective study of patients treated with a Ferrara-type ICRS (manual technique) according to the ectasia phenotype classification. Forty-four eyes were included, with a mean Kmax of 57.3D and mean thinnest point of 457μm. The average patient age was 17.4 years, with the youngest patient being 14 years old. Follow-up was 48 months.
Mean corrected distance visual acuity improved from 0.44 preoperatively to 0.63 at 24 months, while Kmax decreased to 54.1D. Both remained stable at 48 months. No progression was observed during the four years of follow-up in terms of VA, refractive and topographic astigmatism, coma (Z3-1), and the corneal thinnest point. No crosslinking treatment was necessary.
SAFETY PROFILE
“The safety profile of the procedure was very good, as we had no intraoperative complications, no infections and no loss of VA. We did, however, observe two cases of ICRS extrusion and one case of segment exchange,” reported Dr Carneiro de Freitas.
But what should be done in young patients in whom rapid progression is expected? In young patients with high risk of progression who require treatment, primary ICRS implantation is indicated in cases of low VA, high anisometropia and low binocular visual function, he advised. Opposite to corneal crosslinking, the ICRS treatment enables both a therapeutic and refractive approach, improving the VA while treating and stabilising the ectasia at the same time.
“Ferrara ICRSs allow good visual, refractive and topographic results in patients less than 20 years old, and the results remain stable during a follow-up period of four years. Our study results suggest that the procedure is safe and efficacious in younger patients,” he said.
He added that, to date his team has implanted more than 300 ICRSs, and that no additional crosslinking has been necessary to treat ectasia progression after implantation.
Rui Carneiro de Freitas: ruicarneirodefreitas@gmail.com
