Medical Ophthalmology Lecture 14 PDF

Lecture 14: Medical ophthalmology Medical Ophthalmology Eye Manifestations in Systemic Diseases Many systemic diseases, as well as drugs used to treat them, have significant ocular manifestations. The most common systemic diseases affecting the eye include: 1. Infectious diseases...

Lecture 14: Medical ophthalmology Medical Ophthalmology Eye Manifestations in Systemic Diseases Many systemic diseases, as well as drugs used to treat them, have significant ocular manifestations. The most common systemic diseases affecting the eye include: 1. Infectious diseases. 2. Blood disorders. 3. Collagen diseases. 4. Endocrine disorders. 5. Metabolic diseases. 6. Nutritional deficiencies. 7. Intoxications. 1. Infectious Diseases 1. Kerato-Conjunctivitis: This can be part of many viral infections as measles, chicken pox and rubella. Granulomatous infections as tuberculosis and syphilis can produce chronic granulomatous conjunctivitis. 2. Sub-conjunctival hemorrhage: May occur in hemorrhagic fevers as in Rift valley fever, Ebola virus, and spirochaetal diseases. 3. Uveitis: May be a manifestation of many viral infections. Metastatic purulent uveitis (Endophthalmitis) can occur with pyogenic bacteria as in intravenous drug abusers. Granulomatous uveitis occurs with tuberculosis and syphilis.  Lecture 14: Medical ophthalmology 4. Retinitis: Specific forms of retinitis may occur with cytomegalovirus infection in AIDS patients. Acute retinal necrosis can occur with herpes simplex retinitis. Congenital rubella can produce a retinitis pigmentosa like disease in the newly born (salt and pepper fundus). Cysticercosis may give rise to sub- retinal parasitic cysts and toxocara species can produce a retinal granuloma. 5. Optic neuritis and subsequently optic atrophy: Can occur with encephalitis and meningitis of viral or bacterial origin. Optic atrophy may be a complication of therapy as with the use of ethambutol (anti- tuberculous drug). 6. Orbital parasitic cysts: May be seen in hydatid disease (Echinococcus granulosus) and myositis of the extra-ocular muscles is a characteristic feature of trichenella spiralis infestation. 2. Blood Diseases 1. Coagulation disorders: As haemophilia, thrombocytopenia and anti-coagulant therapy can produce hemorrhage anywhere in the eye. The most significant of which are vitreous and retinal hemorrhages. 2. Severe anemia: Can produce pallor of the conjunctiva, retinal hemorrhages and optic disc edema. Sickle-cell anemia can produce retinal arteriolar occlusions and retinal neo-vascularization. 3. Hematological malignancies: As leukemias and lymphomas can produce a wide variety of manifestations including sub-conjunctival hemorrhage, orbital infiltrations and proptosis, uveal nodules and retinal pale-centred hemorrhages (Roth spots).  Lecture 14: Medical ophthalmology 3. Collagen Diseases This is a group of diseases involving the joints and connective tissue all-over the body. They include rheumatoid arthritis, systemic lupus erythematosus, polyarteritis nodosa, scleroderma, polymyositis and Sjogren syndrome. 1. Dry eye (Kerato-Conjunctivitis Sicca): Loss of the watery component of tears due to atrophy of the main and accessory lacrimal glands. 2. Keratitis, keratolysis: Spontaneous sterile corneal perforations and scleritis are common manifestations of rheumatoid arthritis. 3. Irido-cyclitis: Is common with pauci-articular juvenile rheumatoid arthritis. 4. Systemic lupus erythematosus and polyarteritis nodosa: Produce a variety of retinal and choroidal vascular occlusions with the most common manifestation being cotton-wool spots of the retina. 4. Endocrinal Disorders 1. Retinal changes in diabetes. 2. Metabolic cataract can be seen in diabetes, Cushing's syndrome and hypo para- thyroidism. 3. Proptosis and extra-ocular muscle disorders are seen in dysthyroid eye disease. 4. Optic nerve, compression and bitemporal hemianopia are common manifestations of pituitary adenomas.  Lecture 14: Medical ophthalmology Ocular Manifestations of Diabetes: 1. Lids: Recurrent styes, chalazia and blepharitis. Xanthelasma. 2. Cornea: Recurrent corneal erosions. 3. Iris: Rubeosis iridis. Iritis. 4. Retina: Diabetic retinopathy (chapter of the retina). 5. The lens: Cataract a. True diabetic cataract. b. Presenile cataract. 6. Changes in refraction:  Hyperglycemia causes myopia.  Hypoglycemia causes hypermetropia. 7. Optic Nerve:  Diabetic neuritis.  Optic atrophy.  Ischemic optic neuropathy. 8. Paralytic squint: The commonest is lateral rectus paralysis.  Lecture 14: Medical ophthalmology 5. Metabolic Diseases 1. Metabolic cataract (Sun-flower cataract): Can be seen in Galactosaemia, renal rickets as Lowe's syndrome and in Wilson's diseases. 2. Subluxated lens is seen in Marfan's syndrome and Homocystinuria. 3. Corneal deposites are seen in Wilson's disease. 4. Corneal infiltrates and oedema is a common manifestation of Mucopoly- saccharidosis and corneal crystals are seen in Cystinosis. 5. Lid nodules (Xanthelasma) are a common feature of hyper-lipidaemias. 6. Cherry-red spot of the fovea is a common finding in Sphingo-lipidoses and Muco-lipidoses as Tay-Sachs disease and Niemann-Pick disease. 7. Optic atrophy is common in many end-stage metabolic disorders. 6. Nutritional Deficiencies 1. Vitamin A deficiency: Causes xerosis of the conjunctiva, keratomalacia in severe cases and night blindness. 2. Vitamin B deficiency: As in beri-beri and tobacco-alcohol amblyopia can produce ophthalmoplegia and optic atrophy. 3. Vitamin C deficiency and other anti-oxidants: May predispose to cataract and age-related macular degeneration (ARMD).  Lecture 14: Medical ophthalmology 7. Drug and Chemical Intoxication 1. Blepharo-conjunctivitis: Is common with much topical and systemic medication causing: Allergy as with the use of sulphonamides. Darkening of the conjunctiva (Argyrosis) due to prolonged use of topical and systemic Silver preparations. Lid and conjunctival pigmentation can occur with prolonged use of Latanoprost and Epinephrine (anti-glaucoma medications). Immuno-Suppressive drugs can cause bacterial and fungal infections. 2. Corneal deposits can be seen in Amiodarone therapy and various Quinine derivatives. 3. Cataract and open angle glaucoma are common features of long-term corticosteroid therapy. 4. Closed angle glaucoma can occur in predisposed eyes with the use of atropine derivatives as antispasmodics and antidepressants. 5. Changes in the pupil size occur with drugs affecting the autonomic nervous system. Paresis of accommodation is common with atropine derivatives while spasm of accommodation occurs with organo-phosphorus poisons. 6. Paresis of the extra-ocular muscles is seen with chronic lead poisoning causing binocular diplopia. 7. Retinal toxicity is a feature of chronic therapy with Phenothiazines (pigmentary retinopathy), Chloroquines (maculopathy) and Tamoxifen (used in breast cancer therapy). 8. Papilledema and increased intra-cranial tension can occur with chronic therapy with vitamin A, Corticosteroids and Tetracyclines. 9. Optic atrophy can occur from various intoxications as Methyl alcohol, Lead poisoning, anti-tuberculous drugs.  Lecture 14: Medical ophthalmology Laser in Ophthalmology Definition: The word laser is derived from a concise definition of their mechanism of action "Light Amplification by Stimulated Emission of Radiation". Character: 1. Mono-chromatic (one wave length). 2. Uni-directional (parallel to each other with little tendency to diverge over distance). 3. Coherent (its waves moves in phase to strengthen each other). Uses of Lasers in Ophthalmology: According to their mechanism of action in the eye types of LASER were divided into: ) Photo coagulating. ) Photo disrupting. III) Photo vaporizing. VI) Photo dynamic.  Lecture 14: Medical ophthalmology ) Photo Coagulating Laser Principle:  Depends on absorption of LASER by ocular pigments such as Xanthophyl, Melanin and Haemoglobin.  LASER energy is converted into heat to induce coagulation. Types: a. Gas as Argon (wave length 532 nanometer). b. Solid as Diode (wave length 910 nanometer). Indications: A. Anterior Segment: 1. Removal of eye lid tumors. 2. Destroying lash roots in trichiasis. 3. Cutting sutures (after cataract & glaucoma operations). 4. Iridotomy for treatment of closed angle glaucoma. 5. Trabeculoplasty for treatment of open angle glaucoma. 6. Cyclo-photo-coagulation of the ciliary processes to treat resistant glaucoma. B. Posterior Segment: 1. Pan Retinal Photocoagulation PRP (the most common indication) for treatment of Proliferative Diabetic Retinopathy PDR and central retinal vein occlusion CRVO. 2. Macular edema. 3. Destruction of intra-ocular tumors.  Lecture 14: Medical ophthalmology ) Photo Disrupting Laser Principle: Optical breakdown of membranes or thin tissues. Example: Gases as Neodymium-YAG (Nd-YAG) LASER (infra red). Indications: A. Anterior Segment: 1. Posterior capsulotomy after cataract surgery which is the most common indication. 2. Iridotomy for treatment of closed angle glaucoma. 3. Breaking of synechiae following irido-cyciltis. B. Posterior segment  Breaking of vitreous strands or membranes.  Lecture 14: Medical ophthalmology ) Photo Vaporizing Laser Principle:  LASER causes breakdown of bonds between molecules of tissues leading to their vaporization. Example: Gas as Argon- Fluoride (Excimer) LASER Indications: 1. Correction of refractive errors (myopia, hypermetropia and astigmatism). 2. Fine excision of abnormal corneal tissues (plaques or nodules). V) Photo Dynamic Therapy Laser (PDT): Principle: Depends on intravenous injection of a radio-active substance which has a great affinity to abnormal vascular tissues, then these tissues are exposed to certain types of LASER as Diode LASER to destroy it. Indications: Treatment of sub-retinal neo-vascular membranes at the macular area.