Changes in the micromorphology of the corneal subbasal nerve plexus in patients after plaque brachytherapy

Abstract

BackgroundTo quantify the development of radiation neuropathy in corneal subbasal nerve plexus (SNP) after plaque brachytherapy, and the subsequent regeneration of SNP micromorphology and corneal sensation.MethodsNine eyes of 9 melanoma patients (ciliary body: 3, iris: 2, conjunctiva: 4) underwent brachytherapy (ruthenium-106 plaque, dose to tumour base: 523 ± 231 Gy). SNP micromorphology was assessed by in-vivo confocal microscopy. Using software developed in–house, pre-irradiation findings were compared with those obtained after 3 days, 1, 4 and 7 months, and related to radiation dose and corneal sensation.ResultsAfter 3 days nerve fibres were absent from the applicator zone and central cornea, and corneal sensation was abolished. The earliest regenerating fibres were seen at the one-month follow-up. By 4 months SNP structures had increased to one-third of pre-treatment status (based on nerve fibre density and nerve fibre count), and corneal sensation had returned to approximately two-thirds of pre-irradiation values. Regeneration of SNP and corneal sensation was nearly complete 7 months after plaque brachytherapy.ConclusionsThe evaluation of SNP micromorphology and corneal sensation is a reliable and clinically useful method for assessing neuropathy after plaque brachytherapy. Radiation-induced neuropathy of corneal nerves develops quickly and is partly reversible within 7 months. The clinical impact of radiation-induced SNP damage is moderate.

Morphometrische Charakterisierung des subbasalen Nervenplexus

“…Darüber hinaus können mehrere Untersuchungen desselben SNP zu verschiedenen Zeitpunkten durchgeführt werden, um dynamische Veränderungen seiner Mikromorphologie zu erfassen. Dies ist besonders im Rahmen von Verlaufsuntersuchungen [29] oder nach operativen Eingriffen wie refraktiver Hornhautchirurgie und Hornhauttransplantationen [24] von Interesse. In einer Reihe von Studien konnte gezeigt werden, dass sich Verän-derungen des peripheren Nervensystems in der Konfiguration von Nervenfasern des SNP manifestieren [12,27,28].…”