It is known that pterygia above a certain size cause astigmatism and other aberrations of the human cornea and impair vision quality. Researchers in Switzerland have determined the extent to which strontium/yttrium-90 beta irradiation affects higher order corneal aberrations (HOAs). They advise to start irradiation as early as possible with a horizontal pterygium length of less than 2mm before the induction of significant corneal aberrations.
The study evaluated corneal topographies and wavefront aberration data of 20 primary pterygia patients generated before and at different points in time in the first year after irradiation. It also measured the size of the pterygium.
The researchers noted a significant increase in vertical and horizontal coma and triple leaf aberrations in pterygia with a horizontal length of 2mm and more. They could not detect any changes in spherical aberration, but the subgroup analysis with different measuring points showed that horizontal coma increased continuously over time within the first seven months after irradiation. They also determined that a pterygium size greater than 2mm significantly induced astigmatism. The study found no pterygium recurrence in any of the patients after irradiation.
“Exclusive strontium/yttrium-90 beta irradiation of the pterygium is a very effective and, to date, recurrence-free and safe treatment method against primary or recurrent pterygia,” the researchers concluded. “We recommend that a secondary surgical excision of the pterygium be considered if the pterygium was greater than 2mm before beta irradiation and if, at the same time, the HOAs increased significantly after strontium/yttrium-90 application.”
Rigendinger F, Aebersold DM, Cvejic Z, Pajic B. Changes of corneal biomechanical properties upon exclusive ytt-/sr-90 irradiation of pterygium. Sensors (Basel). 2021;21(3):975.