HIF1A and pterygium: Unexpectedly, primary and recurrent pterygium revealed lower immunoreactivity of HIF1α (11% ± 20%, and 18% ± 36%) and HIF2α (38% ± 31%, and 21% ± 27%), respectively, in epithelial cells when compared to healthy conjunctiva (HIF1α: 46% ± 30% and HIF2α: 66% ± 31%).