Glaucoma (PDF)

Lecture Material is adapted from © 2017 Wolters Kluwer Health, Lippincott Williams & Wilkins Applied Pathophysiology: A Conceptual Approach to the Mechanisms of Disease Chapter 12: Altered Somatic and Special Sensory Function Module 4: Clinical Models Copyright © 2...

Lecture Material is adapted from © 2017 Wolters Kluwer Health, Lippincott Williams & Wilkins Applied Pathophysiology: A Conceptual Approach to the Mechanisms of Disease Chapter 12: Altered Somatic and Special Sensory Function Module 4: Clinical Models Copyright © 2017 Wolters Kluwer Health | Lippincott Williams &Wilkins  Glaucoma Clinical Diagnostic Pathophysiology Treatment manifestations criteria Porth C. Pathophysiology : concepts of altered health states. 7th ed. Philadelphia, Lippincott Williams & Wilkins; 2005.  Glaucoma Pathophysiology Second leading cause of blindness among elderly Leading preventable blindness Gender differences Up to age 65: more women are affected After: no difference in rates Among Blacks it is more prevalent Often silent progression In Australia: http://www.glaucoma.org.au/what.htm  Glaucoma Pathophysiology Vision loss is due to optic nerve damage Increased intraocular pressure is a risk factor Not always present Categories 1. Primary open angle http://www.glaucoma.org/glaucoma/do es-blood-pressure-affect-glaucoma.php Open angle Clogged trabecular network at the point where the iris and cornea meet Impaired aqueous humor drainage leading to increased intraocular pressure (IOP) 2. Angle closure (or narrow angle) Rapid IOP from blocked aqueous humor drainage Complete closure is a crisis Closed angle Asian descent, hyperopia 3. Normal tension Normal IOP Progressive damage Poor blood flow to optic nerve  Glaucoma Clinical Manifestations Risk factors Age Black race http://www.glaucoma.org/glaucoma/do es-blood-pressure-affect-glaucoma.php Diabetes Eye trauma Long-term steroid use Primary open angle Cornea adapts to increasing pressure without swelling No subjective symptoms If untreated: gradual, irreversible vision loss Blind spots in field of vision decreased blood supply to areas of the retina due to IOP Initially limited to periphery Progresses centrally Responds well to pharmacologic treatment  Glaucoma Clinical Manifestations Complete acute angle closure: Acute glaucoma crisis Induced by Increased pupil dilation caused by drugs (anesthesia: atropine) or being in darkened room, excitement, stress Permanent damage to optic nerve leads to vision loss is rapid (days to weeks) Eye pain Headache Nausea Blurred vision Rainbows around lights at night May result in chronic glaucoma and cataracts Greater chance to cause permanent vision loss  Glaucoma Diagnostic Criteria Early detection better outcome, management, decreasing loss of vision Tonometry Measure intraocular pressure (non-contact, air-puff) Ophthalmoscopic exam Fundus examination Detecting changes Optic nerve cupping (as nerve fibers begin to die, the center portion http://www.glaucoma.org/treatment/optic-nerve-cupping.php of the optic disc “cup” becomes larger), progressive Pallor (pale appearance of damaged optic nerve) Hemorrhage Visual field assessment Confocal laser optical coherence http://www.aao.org/eyenet/article/disc-hemorrhages-in-eyes-with-glaucoma?may-2014  Glaucoma Treatment Pharmacologic treatment I. Increase outflow of fluid Miotics Epinephrine-based medication II. Decrease fluid levels Beta blockers Carbonic anhydrase inhibitors Alpha-adrenergic agonists III. Increase fluid flow through secondary drainage Prostaglandin analogs  Glaucoma Treatment Surgical treatment Laser surgery Trabeculoplasty: correction of the trabecular network to promote fluid outflow from the eye in open-angle glaucoma Iridotomy: incision into the iris to promote fluid outflow Cyclophotocoagulation: correction of ciliary tissue to decrease the production of fluid Conventional surgery Trabeculectomy: surgical removal of a small portion of the trabecular meshwork under the lid to http://www.hopkinsmedicine.org/wilmer/glaucoma_center_e xcellence/book/chapter_angle_closure_suspect.html create new drainage