ALTERATIONS IN FUNCTION OF SPECIAL SENSES

1. ALTERATIONS IN FUNCTION OF SPECIAL SENSES

2. Conjunctivitis Inflammation of the conjunctiva. Pathophysiology: bacterial or viral infection, allergens, chemical agents, physical irritants or radiant energy. Depending on the cause, conjunctivitis can vary in severity from a mild hyperaemia with tearing to severe conjunctivitis with purulent discharge. Bacterial Conjunctivitis: acute, hyper-acute or chronic. Viral Conjunctivitis: Adenovirus 3 and 7. Allergic Conjunctivitis: seasonal allergic rhinoconjunctivitis.

3. Keratitis Inflammation of the cornea. Pathophysiology: It can be caused by infections, misuse of contact lenses, hyper-sensitivity reactions, ischemia, trauma, defects in tearing. Scar tissue formation due to keratitis is the leading cause of blindness and impaired vision throughout the world. Non-ulcerative vs. Ulcerative Herpes Simplex Keratitis: irritation, photophobia and tearing; ocular morbidity.

4. Cataracts A lens opacity that interferes with the transmission of light to the retina. Pathophysiology: As the lens ages, new layers of fibres are added and the lens nucleus is compressed and becomes harder, with associated yellowing of the lens. Earliest symptom: improved near vision without glasses. Other causal factors include: heredity, environmental and metabolic influences, drugs and trauma, long term exposure to sunlight, and heavy smoking. Metabolically induced cataracts are caused by disorders of CHO metabolism or inborn errors of metabolism.

5. Retinopathies Involve the small blood vessels of the retina, are characterised by changes in vessel structure. Diabetic Retinopathy: One of the leading causes of blindness in the West. Chronic hypoglycaemia, hypertension, hypercholesteremia and smoking are all risk factors. Non-proliferative vs. Proliferative Macular Degeneration: characterised by degenerative changes in the central portion of the retina that result in loss of central vision. Non-neovascular vs. Neovascular

6. Glaucoma Is a chronic, degenerative optic neuropathy characterised by optic disk cupping and visual field loss. It is usually associated with an elevation in intraocular pressure. Glaucoma is the second leading cause of blindness in the world. Pathophysiology: usually results from congenital or acquired lesions of the anterior segment of the eye that mechanically obstructs aqueous outflow. Open-angle glaucoma vs. Glaucoma closure Abnormality of the trabecular meshwork that controls the outflow of aqueous humour into the canal of Schlemm. Primary or Secondary Occlusion of anterior chamber angle of the iris.

7. Otitis Media Inflammation of the middle ear without reference to aetiology or pathogenesis. Acute Otitis Media vs. Otitis Media with effusion Pathophysiology: URI Clinical Manifestation: otalgia, fever and hearing loss

8. Tinnitus Perception of abnormal ear or head noises not produced by an external stimulus. Constant, Intermittent and Unilateral Objective tinnitus vs. Subjective tinnitus Pathophysiology: Impacted cerumen

9. Disorders of Peripheral Vestibular Function Acute Vestibular Neuronitis: inflammation of the vestibular nerve and is characterised by the onset of vertigo, nausea and vomiting. Pathophysiology: suspected viral origin; Herpes Zoster Virus. Meniere Disease: disorder of the inner ear due to distension of the endolymphatic compartment of the inner ear, causing a triad of hearing loss, vertigo and tinnitus. Pathophysiology: Increased production of endolymph, decreased production of perilymph accompanied by a compensatory increase in volume of the endolymphatic sac. Cause: Unknown. Ear fullness, tinnitus, violent rotary vertigo that often renders the person unable to sit or walk.