symptoms of eye disorders
eye disorders
Double Vision
Monocular double visioncan occur when something distorts light transmission through the eye to the retina (the light-sensing structure at the back of the eye). There may be more than 2 images. One of the images is of normal quality (for example, in brightness, contrast, and clarity). The other image or images are of inferior quality. The most common causes ofmonocular double visionare Clouding of the lens of the eye ( Cataract ) Problems with the shape of the cornea (for example, Keratoconus , in which the cornea changes from its normal round shape to a conelike shape) Uncorrected Overview of Refractive Disorders , usually astigmatism Refractive error is imperfect focusing of light rays on the retina. What Is Astigmatism? is refractive error caused by abnormal curvature of the cornea (the clear layer in front of the iris and pupil). Other causes of monocular double vision include corneal scarring and a dislocated lens. Binocular double visionsuggests the eyes are not pointing at the same object. People normally see an object as a single image even though each eye receives its own separate image of that object. To perceive single images, the eyes must be aligned so that both point to the same object at the same time (called conjugate alignment). When the eyes are not properly aligned, people see 2 images, both of equal quality. Sometimes binocular double vision becomes apparent only when people move their eyes to an extreme in a certain direction (for example, to the far right or left, or up or down). There are many possible causes ofbinocular double vision. The most common are Paralysis of one of the nerves that controls the muscles that move the eye (the third, fourth, and sixth cranial nerves) Myasthenia Gravis None Mechanical blockage of eye movement Most commonly, the eyes are misaligned because of a disorder affecting the cranial nerves supplying the muscles that move the eyes, called Third Cranial Nerve (Oculomotor Nerve) Palsy . The paralysis may be isolated and the cause may be unknown. Known causes include disorders that typically interfere with the ability of the nerves to control muscles. For example, Anything that mechanically interferes with eye motion can keep the eyes from aligning properly and cause double vision. Examples include entrapment of an eye muscle in a fracture of the eye socket and deposition of abnormal tissue in the eye socket as can occur with the form of hyperthyroidism called Causes . 