Anterior blepharitis affects the outside of the eyelid where your eyelashes are attached. This can be caused by bacterial (or sometimes viral) infection. If left untreated, anterior blepharitis can lead to thickened and inward-turned or outward-turned eyelids and even vision problems from in-turned eyelashes damaging the cornea.
More: http://www.geteyesmart.org/eyesmart/diseases/blepharitis.cfm
Source: Eye Smart
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