Abstract
Purpose: :
Pterygia are fibrovascular degenerations contiguous with conjunctiva and cornea. They are associated with ultraviolet light exposure. Pterygia encroachment into the visual axis induces significant astigmatism and irritation. Pterygia are commonly treated surgically but have a recurrence rate as high as 40%. Treatment with corticosteroids is hypothesized to delay pterygium progression. This study assesses the efficacy of 0.5% loteprednol etabonate (LE) by comparing glucocorticoid receptor (GCR) migration with clinical outcomes after steroid therapy.
Methods: :
Ten patients with mild to severe pterygium were treated with topical LE four times daily for two weeks prior to surgical excision. Pterygium biopsies were studied from steroid treated pterygia, treated normal conjunctiva (biopsied from the same eyes as steroid treated pterygia donors, but from a different site), and untreated naïve conjunctiva from untreated volunteers. Samples were homogenized in RIPA Buffer and supernatant collected for protein and Western blot analysis. GCR activation was measured as a function of GCR migration from the cytosol into the nucleus. Clinical evaluation was performed by the treating physician.
Results: :
Untreated naïve conjunctiva GCR protein concentration was 1.2±0.4 µg/µl (n=3). Treated normal conjunctiva GCR protein concentration was 1.6±0.5 µg/µl (n=7). Corneal pterygium GCR protein concentration was elevated to 3.0±0.9 µg/µl (n=7). GCR migration in treated pterygia was 48±9% greater than in naïve conjunctiva (p<0.001). In normal conjunctiva, steroid treatment increased GCR migration by 18±7% (p <0.05). Clinically, the patients responded well to the therapy and were without recurrence at six months.
Conclusions: :
GCR migration activity increased significantly following treatment with LE. The receptor migration was most pronounced in the pterygium tissue with less effect on normal treated and untreated conjunctiva. These findings suggest that perioperative treatment with topical LE may result in favorable clinical outcomes in pterygium removal.
Keywords: pterygium • corticosteroids • signal transduction: pharmacology/physiology