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Refractive Error and Presbyopia
Very good information about refractive error and presbyopia. Refractive error exists when light does not focus perfectly onto the retina.
Healthline Media
Medical News Today: Articles: Eye Health: What Is Astigmatism?
Learn about astigmatism, a type of refractive error where the eye does not bend light properly, thereby causing blurred vision. Also explained are the causes, treatment, and diagnosis of astigmatism.