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Information about CATARACT

Published on February 25, 2014

Author: shyammohanvet


CATARACT: CATARACT SHYAM MOHAN BVN 09067 PowerPoint Presentation: Cataracts are nonspecific disease that results in opacification of the lens fibers or capsule DEFINITION; An opacity of the lens of the eye or the membrane that covers it, causing impairment of vision or blindness. PowerPoint Presentation: CORNEA SCLERA IRIS ANTERIOR CHAMBER POSTERIOR CHAMBER ANTERIOR SEGMENT + LENS ANTERIOR LENS CAPSULE POSTERIOR LENS CAPSULE ZONULE VITREOUS / POSTERIOR SEGMENT CILIARY BODY CHOROID RETINA OPTIC DISC OPTIC NERVE PowerPoint Presentation: IN NORMAL VISION; Animal look at an object Light rays are reflected from the object to the cornea. A healthy trasparent Lens focuses the rays to the retina PowerPoint Presentation: CLASSIFICATION Congenital cataract: Cataract present at birth. Acquired cataract: cataract developing later in life Complete cataract : involving the lens completely Partial cataract Progressive cataract Stationary cataract PowerPoint Presentation: Senile cataract: cataract developing due to old age Diabetic cataract: characterized by minute opacities developing on the superficial cortex of the lens due to turgidity of cells in the superficial cortex of the lens. The turgidity of cells apparently associated with the sugar content of the aqueous humour Toxic cataract : cataract caused by the circulations of toxins or poisons in the body PowerPoint Presentation: Capsular cataract: is two types (anterior capsular cataract and posterior capsular cataract) Cortical cataract- majority of cortical cataracts are stellate cataracts(spreading from the centre of the lens to its periphery) Pyramidal cataract – a localized opacity of the lens . Lamellar cataract- the opacity is seen in the area between the lens nucleus and cortex Perinuclear cataract – this is lamellar cataract seen in horses PowerPoint Presentation: Nuclear cataract – confined to the central portion of the lens Diffuse cataract – spreading evenly through the entire lens . Calcareous cataract- cataract in which the substances is partly converted into chalky materials. PowerPoint Presentation: INCIPIENT CATARACT: Focal opacification of the lens or its capsule characterizes an incipient cataract. IMMATURE CATARACT: In an immature cataract , opacity is more or less diffuse, although these may be areas of variable density. The fundic reflex is present, and the animal may experience some visual impairment. PowerPoint Presentation: MATURE CATARACT : A mature cataract shows total dense opacification of the lens with absense of the fundic reflex, visual function is significantly Impaired. Cataract surgery is recommended at this stage. HYPERMATURE CATARACT: Lens protein liquefies,and may leak through the capsule. PowerPoint Presentation: If leakage is extensive with significant resorption of protein the lens capsule become wrinkled,initially at the equator. The nucleus,which is insoluble albuminoid protein, may migrate inferiorly within the lens capsule to form a morgagnian cataract . Uveitis may result from leakage of lens protein. The fundic reflex may be present peripherally and the animal may see if resorption is extensive. PowerPoint Presentation: Etiology Hereditary – Bilateral Infections or toxins Trauma Senile - ≥ 6 years of age Diabetes Harmful oxidizing effects in the body Dietary deficiency PowerPoint Presentation: Normal lens is maintained in a dehydrated state (66% water and 33% protein ) complicated sodium water pump-keeps water/protein in balance state. Changes in the biomechanical system in the lens - water moves into the lens (alter the lens osmolarity ) percentage of insoluble protein increases. loss of transparency and cataract formation . HOW DOES CATARACT FORM PowerPoint Presentation: Diagnosis Ophthalmic examination 1. Day light examination. Menace reflex. Maze test. Cotton ball test. Direct and indirect Ophthalmoscopic examination Tonometry PowerPoint Presentation: Indirect Ophthalmoscopy PowerPoint Presentation: Treatment Discission or needling: The anterior capsule of the lens is incised in a cruciate fashion, using a cataract needle so that the aqueous humour will come in contact with the lens substance and will facilitate re-absorption of the opacity. Discission will have to be repeated periodically to obtain the desired effect. PowerPoint Presentation: OPERATION PROCEDURES: The surgical procedure in phacoemulsification for removal of cataract involves a number of steps. Each step must be carefully and skillfully performed in order to achieve the desired result: 1.Anaesthesia, 2.Exposure of the eyeball using a lid speculum, 3.Entry into the eye through a minimal incision (corneal or scleral) 4.Viscoelastic injection to stabilize the anterior chamber and to help maintain the eye pressurization PowerPoint Presentation: 5.Hydrodissection pie 6.Hydro-delineation 7.Ultrasonic destruction or emulsification of the cataract after nuclear cracking or chopping (if needed), cortical aspiration of the remanescent lens, capsular polishing (if needed) 8.Implantation of the, usually foldable, intra-ocular lens (IOL) 9.Viscoelastic removal 10.Wound sealing / hydration (if needed). PowerPoint Presentation: TYPES OF SURGERY There are three main types of cataract surgery: Phacoemulsification ( Phaco ) is the preferred method in most cases. It involves the use of a machine with an ultrasonic handpiece equipped with a titanium or steel tip. The tip vibrates at ultrasonic frequency (40,000 Hz) and the lens material is emulsified . PowerPoint Presentation: PHACOEMULSIFICATION INSTRUMENT PowerPoint Presentation: PHACOEMULSIFICATION UNIT PowerPoint Presentation: PHACOEMULSIFICATION The eye is entered with a small incision. the lens capsule is carefully opened in a technique called capsulotomy And the lens is removed by the phaco instrument which emulsifies the lens into a mulch with ultrasonic waves and aspirates the remnants PowerPoint Presentation: EXTRACAPSULAR CATARACT EXTRACTION (ECCE): Extracapsular cataract extraction involves the removal of almost the entire natural lens while the elastic lens capsule (posterior capsule) is left intact to allow implantation of an intraocular lens. It involves manual expression of the lens through a large (usually 10–12 mm) incision made in the cornea or sclera . PowerPoint Presentation: INTRACAPSULAR CATARACT EXTRACTION Intracapsular cataract extraction (ICCE) involves the removal of the lens and the surrounding lens capsule in one piece. The procedure has a relatively high rate of complications due to the large incision required and pressure placed on the vitreous body . After lens removal, an artificial plastic lens (an intraocular lens implant) can be placed in either the anterior chamber or sutured into the sulcus. PowerPoint Presentation: INTRAOCULAR LENSES Intraocular lens implantation: After the removal of the cataract, an intraocular lens (IOL) is usually implanted into the eye, either through a small incision (1.8 mm to 2.8 mm) using a foldable IOL, or through an enlarged incision, using a PMMA ( polymethylmethacrylate ]lens. The foldable IOL, made of silicone or acrylic material. PowerPoint Presentation: TYPES OF IOL The monofocal intraocular lenses are the traditional ones, which may provide vision at one distance only: far, intermediate, or near These intraocular lenses are usually spherical, and they have their surface uniformly curved. The multifocal intraocular lenses are ones of the newest types of such lenses. They are often referred to as "premium" lenses because they are multifocal and accommodative and allow the patient to visualize objects at more than one distance, removing the need to wear eyeglasses or contact lenses. PowerPoint Presentation: Complications 1. PVD — Posterior vitreous detachment. 2. Posterior capsular tear. 3. Retinal detachment . 4. Toxic Anterior Segment Syndrome. 5. Endophthalmitis . 6. Glaucoma. 7. Macular edema . PowerPoint Presentation: THANK U

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