Cataract (opthalmology)
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Cataracts are a clouding of the lens of the eye that can cause gradual vision loss. They are usually caused by aging but can be caused by other factors like diabetes, smoking, or UV exposure. Cataracts are diagnosed based on a decrease in the red reflex seen during eye exams. They can be treated surgically through phacoemulsification to remove the clouded lens and replace it with an intraocular lens, improving vision. Age-related macular degeneration (AMD) is a disease of the macula that causes central vision loss. Dry AMD involves drusen buildup while wet AMD has abnormal blood vessel growth. Treatments include vitamins for dry AMD and anti-VEGF injections or photod
Cataract (opthalmology)
- 1. By Muhd Ariff B Mahdzub CATARACT
- 2. CATARACT • Cataract is one of the most common cause of gradual visual loss but is usually treatable. • It refers to “clouding” or loss of clarity of the crystalline lens, with a resultant of decrease in visual acuity. • When it lies on the visual axis or is extensive, it gives rise to visual loss. • A cataract may occur congenitally, but elderly cataracts are much more common as a result of cumulative exposure to environmental and other influences, such as smoking, UV radiation and elevated blood sugar levels.
- 3. • A cataract is a very common cause of blindness, but patients may initially experience glare (with the cortical type), monocular diplopia or a change in refraction, usually a “myopic shift” because of nuclear sclerosis. • Cataracts are recognised by a decrease in the red reflex with resultant poor visualisation of the retina on attempted fundoscopy. • It is important to exclude other co-existing ocular pathologies which may limit the chances of visual recovery after surgery. • A cataract is also the most common cause of leukocoria (white pupil). • Cataract blindness is reversible by microsurgery which aims to improve visual function and is safe, quick and cost-effective
- 4. • Causes of Cataract Primary - Congenital - Age-related Secondary - Trauma - Systemic diseases – diabetes mellitus - Drugs s/a steroid - Others
- 5. • Types of age-related cataracts include: A subcapsular cataract occurs at the back of the lens. People with diabetes or those taking high doses of steroid medications have a greater risk of developing a subcapsular cataract. A nuclear cataract forms deep in the central zone (nucleus) of the lens. Nuclear cataracts usually are associated with aging. A cortical cataract is characterized by white, wedge-like opacities that start in the periphery of the lens and work their way to the center in a spoke-like fashion. This type of cataract occurs in the lens cortex, which is the part of the lens that surrounds the central nucleus.
- 7. Mature cataract (with absent red reflex) visible through the dilated pupil
- 8. Phacoemulsification: • An ultrasound probe is used to emulsify the cataract and aspirate it through a small scleral or corneal wound which needs no sutures. • This surgical technique requires a shorter recovery time. • More recently, femtosecond laser has been introduced to perform some of the steps of the procedure. Ultrasound probe used for phacoemulsification MANAGEMENT
- 9. Cataract extraction can be performed in two basic ways, 1. intracapsular cataract extraction (ICCE), whereby the lens is removed together with its capsule 2. extracapsular cataract extraction (ECCE), whereby the lens is removed leaving the capsule behind, which is the preferred technique.
- 10. INTRAOCULAR LENSES (IOL) TYPES
- 11. 5. AGE-RELATED MACULAR DEGENERATION (ARMD)
- 12. Anatomical Landmarks • The macula is a round area at the posterior pole, lying inside the temporal vascular arcades. It measures between 5 and 6 mm in diameter, and subserves the central 15–20° of the visual field. • Histologically, it shows more than one layer of ganglion cells, in contrast to the single ganglion cell layer of the peripheral retina. • The inner layers of the macula contain the yellow xanthophyll carotenoid pigments lutein and zeaxanthin in far higher concentration than the peripheral retina (hence the full name ‘macula lutea’ – yellow plaque).
- 13. • Retinal pigment epithelium composed of a single layer of cells that are hexagonal in cross-section. The cells consist of an outer non-pigmented basal element containing the nucleus, and an inner pigmented apical section containing abundant melanosomes. • The cell base is in contact with Bruch membrane and at the cell apices multiple thread-like villous processes extend between the outer segments of photoreceptors. • Functions of RPE :- Prevent extracellular fluid leaking into subretinal space from the chorio capillaries and actively pump ions and water out of the subretinal space. Facilitation of photoreceptor. Maintenance of the outer-blood retinal barrier ; inward transport of metabolites and outward transport of metabolic waste products. Storage, metabolism and transport vitamin A in the visual cycle. To absorb stray light
- 15. INTRODUCTION • ARMD is a degenerative disorder affecting the macula and is a disease of the elderly. • Characterized by the presence of specific clinical findings, including drusen which are pale deposits in the macular area, and retinal pigment epithelium (RPE) changes, in the absence of another disorder. Later stages of the disease are associated with impairment of vision. • Initially, drusen do not interfere with vision. • Age-related macular degeneration is a very common cause of bilateral visual loss in the developed world, especially in patients over the age of 65 years.
- 17. CLASSIFICATION Dry (non-exudative, non- neovascular) AMD Most common form. Comprising around 90% Geographic atrophy (GA) is the advanced stage of dry AMD; it has been authoritatively suggested that the term ‘dry AMD’ be used only to describe GA rather than earlier stages of AMD. Usually associated with gradual vision loss (due to collection of drusens formed) Wet (exudative, neovascular) AMD Much less common than dry, but is associated with more rapid progression to advanced sight loss. The main manifestations are Choroidoneovascularization and Pigment epithelial detachment. Retinal angiomatous proliferation (RAP) and polypoidal choroidal vasculopathy (PCV), have been included under the umbrella of neovascular AMD by many authorities.
- 18. Drusen around the fovea (centre of the macula). Exudates and haemorrhage in “wet” age-related macular degeneration.
- 20. • Sclerosis of arteries that nourish the retina sensitive retinal tissue oxygen and nutrients that needs to function and thrive atrophic thinning macular tissues, amorphous deposits, pigmentation in macula.
- 22. MANAGEMENT • No specific treatment yet for non-exudative (dry) ARMD. • Treatment starting at intermediate ARMD, by giving VitaLux, an ocular multivitamin to help delay the progression of the disease and to help maintain healthy vision. • In wet ARMD : - anti-VEGF such as Ranibizumab (Lucentis) or Bevacizumab (Avastin) could be injected intravitreously to prevent new vessels forming. - Photodynamic therapy (PDT) : light-sensitive medicine is injected into the bloodstream. The medicine collects in the abnormal blood vessels under the macula. Laser light is then shone into the eye, which activates the medicine and causes it to create blood clots that block the abnormal blood vessels.
- 23. refference • Kanski's Clinical Ophthalmology - Eighth Edition • Opthalmology an illustrated colour text 3rd edition • Opthalmology at a glance • Lecture Notes Ophthalmology, 11th Edition - James, Bruce, Bron, Anthony • http://www.aao.org/eye-health/diseases/what-is-glaucoma • http://patient.info/doctor/ • http://www.emedicinehealth.com/glaucoma_overview/page7_em. htm#glaucoma_surgery
Editor's Notes
- #3: hgffff
- #6: Cataract maturity • Immature cataract is one in which the lens is partially opaque. • Mature cataract is one in which the lens is completely opaque (Fig. 9.3A). • Hypermature cataract has a shrunken and wrinkled anterior capsule (Fig. 9.3B) due to leakage of water out of the lens. • Morgagnian cataract is a hypermature cataract in which liquefaction of the cortex has allowed the nucleus to sink inferiorly
- #12: The macula is a round area at the posterior pole, lying inside the temporal vascular arcades. It measures between 5 and 6 mm in diameter, and subserves the central 15–20° of the visual field. The fovea is a depression in the retinal surface at the centre of the macula, with a diameter of 1.5 mm– about the same as the optic disc. Histologically, it shows more than one layer of ganglion cells, in contrast to the single ganglion cell layer of the peripheral retina. The inner layers of the macula contain the yellow xanthophyll carotenoid pigments lutein and zeaxanthin in far higher concentration than the peripheral retina (hence the full name ‘macula lutea’ – yellow plaque). Functions of RPE :- Prevent extracellular fluid leaking into subretinal space from the chorio capillaries and actively pump ions and water out of the subretinal space. Facilitation of photoreceptor. Maintenance of the outer-blood retinal barrier ; inward transport of metabolites and outward transport of metabolic waste products. Storage, metabolism and transport vitamin A in the visual cycle. To absorb stray light
- #18: Geographic atrophy :
- #21: Drusen (singular: druse) are extracellular deposits located at the interface between the RPE and Bruch membrane. The material of which they are composed has a broad range of constituents, and is thought to be derived from immune-mediated and metabolic processes of visual receptor in the RPE. Their precise role in the pathogenesis of AMD is unclear, but is positively associated with the size of lesions and the presence or absence of associated pigmentary abnormalities. Age-related drusen are rare prior to the age of 40, but are common by the sixth decade. The distribution is highly variable, and they may be confined to the fovea, may encircle it or form a band around the macular periphery. They may also be seen in the peripheral and mid-peripheral fundus
- #23: Fundus fluorescein angiogram (FFA) test : To determine whether injection of anti VEGF should be continued or not. Stop injection if there is ischemic or scar.