Eye Anatomy, Visual Assessment, and Common Eye Disorders

The eye is an optical system connected to neural tissue. Light must pass through several transparent structures, be focused onto the retina, and then be converted into signals that travel through the optic nerve to the brain. | Structure | Function and clinical meaning | |---|---| | Cornea | The clear anterior surface provides most of the eye’s refractive power. Corneal injury or oedema can cause pain, photophobia, blurred vision, and a hazy appearance. | | Iris and pupil | The iris controls the amount of light entering through the pupil. A fixed, mid-dilated pupil in a painful red eye is a major warning sign for acute angle-closure glaucoma. | | Lens | The lens fine-tunes focus. The ciliary muscle changes lens curvature for near vision. Progressive lens opacity produces a cataract. | | Ciliary body and aqueous humour | The ciliary body produces aqueous humour. It flows from the posterior chamber through the pupil into the anterior chamber, then exits mainly through the trabecular meshwork and canal of Schlemm. Impaired outflow raises intraocular pressure (IOP). | | Vitreous humour...