Eye

Looks like

A 2.4 cm ball of clear jelly behind a clear window, with a lens, a coloured iris and a light-sensing lining.

What it does

Turns light into the signals that become sight.

Keeping it well

Eye tests every two years, sunglasses, breaks from screens, blood-sugar control. Sudden vision loss or pain with redness is an emergency.

Its parts

• Orbit
• Eyelids & lashes
• Eyebrows
• Conjunctiva
• Cornea
• Sclera
• Iris
• Pupil
• Lens
• Ciliary body
• Choroid
• Retina
• Vitreous body
• Aqueous humour & trabecular meshwork
• Lacrimal gland & ducts
• Extraocular muscles
• Wall of right eyeball
• Vascular layer of right eyeball
• Suspensory ligament of right lens
• Right lacrimal apparatus
• Orbital part of right eye
• Anterior chamber of left eyeball
• Wall of left eyeball
• Vascular layer of left eyeball
• Suspensory ligament of left lens
• Left lacrimal apparatus
• Orbital part of left eye
• Anterior chamber of eyeball
• Common tendinous ring
• Posterior segment of eyeball
• Suspensory ligament of eyeball
• Anterior segment of eyeball

Related conditions

• Acromegaly
• Age-related macular degeneration
• Blepharitis & styes
• Botulism
• Burst blood vessel in the eye (subconjunctival haemorrhage)
• Cataract
• Chronic venous insufficiency
• Clotting disorders (thrombophilia & APS)
• Colour blindness
• Conjunctivitis
• Corneal abrasion (scratched eye)
• Deep vein thrombosis
• Dermatomyositis and polymyositis
• Diabetic retinopathy
• Drooping eyelid (ptosis)
• Dry eye disease
• Eye melanoma (uveal melanoma)
• Fibromyalgia
• Fractures
• Fragility fracture
• Frailty & falls in older age
• Glaucoma
• Gout
• Haemophilia & bleeding disorders
• Heat exhaustion & heatstroke
• Hyperparathyroidism
• Hyperthyroidism & Graves' disease
• Idiopathic intracranial hypertension
• Jet lag
• Juvenile idiopathic arthritis
• Keratitis (corneal infection and ulcer)
• Keratoconus
• Lyme disease
• Malnutrition & refeeding syndrome
• Marfan syndrome & connective tissue disorders
• Muscular dystrophy
• Myasthenia gravis
• Neurofibromatosis type 1
• Onchocerciasis (river blindness)
• Osteoarthritis
• Osteogenesis imperfecta (brittle bone disease)
• Osteomalacia & rickets
• Osteomyelitis (bone infection)
• Osteoporosis
• Paget's disease of bone
• Polymyalgia rheumatica
• Presbyopia
• Psoriatic arthritis
• Pterygium (surfer's eye)
• Reactive arthritis
• Retinal artery occlusion (eye stroke)
• Retinal detachment
• Retinal vein occlusion
• Retinitis pigmentosa
• Retinoblastoma
• Retinopathy of prematurity
• Rhabdomyolysis
• Rheumatic fever & rheumatic heart disease
• Rheumatoid arthritis
• Sarcoma
• Sarcopenia
• Scleritis and episcleritis
• Seasonal affective disorder
• Short and long sight (refractive error)
• Sjögren's disease
• Squint & lazy eye
• Stevens–Johnson syndrome / toxic epidermal necrolysis
• Systemic lupus erythematosus
• Temporomandibular joint disorder
• Tetanus
• Toxoplasmosis & CMV
• Trachoma
• Trichinellosis
• Uveitis & iritis
• Varicose veins
• Vitamin B1, C and other deficiencies
• Vitamin D deficiency