Which of the following conditions is NOT directly related to the dysfunction of the eye?

Hypertension is a systemic condition that primarily affects the cardiovascular system, involving elevated blood pressure throughout the body. While hypertension can have secondary effects on various organs, including the eyes—such as hypertensive retinopathy—it itself is not a disorder of the eye. The other options, such as amblyopia, blepharitis, and diplopia, directly involve eye dysfunction. Amblyopia, also known as "lazy eye," is a visual development disorder where one eye fails to achieve normal visual acuity, often due to a lack of proper use during early childhood. Blepharitis is an inflammatory condition affecting the eyelids, often leading to redness, swelling, and crusting, directly impacting eye function and comfort. Diplopia, or double vision, results from issues related to the muscles controlling eye movement or neurological conditions, directly affecting the visual experience. In contrast, hypertension does not directly relate to eye function but can influence eye health as a secondary effect.