Overview of Cataract
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The document provides an extensive overview of cataracts, including their definitions, classifications, pathophysiology, diagnosis, and management options. It explains the different types of cataracts, their symptoms, risk factors, and the surgical techniques used for treatment, highlighting the importance of cataracts as a leading cause of blindness. Various studies indicate that age, environmental factors, and systemic diseases significantly influence cataract development and progression.
Overview of Cataract
- 1. Overview of Cataract Dr. Abhishek Onkar
- 2. • The word Cataract comes from the Greek word meaning “Waterfall” • Until the mid 1700’s, it was thought that cataract was formed by opaque material flowing, like a waterfall into the eye • Senile cataract is an age-related, vision-impairing disease characterized by gradual progressive thickening of the lens of the eye. • It is the world’s leading cause of treatable blindness in adults.
- 3. Cataract • Opacification of the human crystalline lens or its capsule. • Classification- -Etiological -Morphological
- 4. The lens
- 5. The lens o Is the second major refractive element of the eye o Grows throughout life. o supported by zonular fibres running between the ciliary body and the lens capsule. o Comprises an outer collagenous capsule under whose anterior part lies a monolayer of epithelial cells. o Towards the equator the epithelium gives rise to the lens fibres. o The zonular fibres transmit changes in the ciliary muscle allowing the lens to change its shape and refractive power. o The lens fibres make up the bulk of the lens. o They are elongated cells arranged in layers which arch over the lens equator. o Anteriorly and posteriorly they meet to form the lens sutures. o With age the deeper fibres lose their nuclei and intracellular organelles. o The oldest fibres are found centrally and form the lens nucleus; the peripheral fibres make up the lens cortex. o The high refractive index of the lens arises from the high protein content of the fibres
- 6. Differential diagnosis Painless, progressive diminution of vision • Cataract • Primary open angle glaucoma • Diabetic retinopathy • Age related macular degeneration • Corneal dystrophies and degenerations • Retinitis pigmentosa
- 7. Morphological classification • Capsular cataract -Anterior -Posterior • Subcapsular cataract -Anterior -Posterior • Cortical cataract • Nuclear cataract • Polar cataract
- 8. Etiological classification I. Congenital and Developmental cataract II. Acquired cataract • Senile cataract • Traumatic cataract (blunt, penetrating, radiation, electric shock, glass blowers, infra-red) • Complicated cataract (uveitis-induced) • Metabolic cataract (Diabetes - snowflake, Wilson’s disease-sunflower) • Drug induced cataract- corticosteroids, miotics • Cataract associated with syndromes
- 9. • Congenital or Developmental cataract - Occur due to maternal infection or malnutrition, perinatal hypoxia – APH, or may be hereditary - Various morphological forms: – Blue dot – Sutural – Fusiform or spindle shaped – Embryonal nuclear – Zonular – Coronary – Anterior or posterior polar
- 10. Senile cataract • ‘Age-related cataract’ • By the age of 70 years, over 90% of the individuals develop senile cataract • Usually bilateral, but almost always asymmetrical
- 11. Types of Senile cataract 1. Cortical cataract 2. Nuclear or sclerotic cataract
- 12. Cortical cataract Etio-pathogenesis:- Hydration followed by coagulation of lens proteins in the cortex. stages :- 1. Stage of lamellar separation 2. Stage of incipient cataract 3. Immature senile cataract 4. Mature senile cataract 5. Hypermature senile cataract
- 13. Stage of lamellar separation • Demarcation of cortical fibres owing to their separation by fluid. • Demonstrated by Slit-lamp examination only. • Characteristic grey appearance of pupil. • Changes are reversible.
- 14. Stage of Incipient cataract • Wedge shaped opacities with clear areas in between( Lens striae). • Most common in periphery and lower nasal quadrant. • Only seen in dilated pupil. • Irregularities in refraction, visual deterioration and polyopia.
- 15. Immature senile cataract • Opacification becomes more diffuse and irregular. • Lens is swollen. • Iris shadow still visible. • Anterior chamber becomes shallow.
- 16. Mature senile cataract • Complete opacification. • Whole cortex is involved . • Lens appears pearly white in colour. • Also known as ripe cataract.
- 17. Hyper-mature senile cataract • Cortex is disintegrated and transformed into pultaceous material. Usually occurs in two forms:- • 1. Morgagnian hyper–mature cataract • 2. Sclerotic hyper–mature cataract
- 18. Morgagnian hyper–mature cataract • Complete cortex is liquefied and appears milky white in colour. • Nucleus settles at the bottom. • Calcium deposits may also be seen on the lens capsule.
- 19. Sclerotic hyper–mature cataract • Disintegrated cortex. • Shrunken lens. • Wrinkled anterior capsule . • Dense white capsular cataract in pupillary area. • Deep Anterior-Chamber. • Tremulous Iris .
- 21. Nuclear or Sclerotic cataract • Etio-pathogenesis:- Intensification of age related degenerative changes associated with dehydration of and compaction of nucleus. Features:- • Hard cataract is formed. • Significant increase in water insoluble protein. • Lens becomes in-elastic and looses power of accommodation. • Changes begin centrally and slowly spread to periphery. • Deposition of pigments gives characteristic colour to nucleus.
- 24. Pathophysiology • The pathogenesis is multifactorial involving complex interactions between various physiologic processes modulated by environmental, genetic, nutritional, and systemic factors. • As the lens ages, its weight and thickness increases while its accommodative power decreases. • As the new cortical layers are added in a concentric pattern, the central nucleus is compressed and hardened in a process called nuclear sclerosis.
- 25. • Multiple mechanisms contribute to the progressive loss of transparency of the lens. • The lens epithelium is believed to undergo age-related changes, particularly a decrease in lens epithelial cell density and an aberrant differentiation of lens fiber cells. • Although the epithelium of cataractous lenses experiences a low rate of apoptotic death, which is unlikely to cause a significant decrease in cell density, the accumulation of small scale epithelial losses may consequently result in an alteration of lens fiber formation and homeostasis, ultimately leading to loss of lens transparency. • Furthermore, as the lens ages, a reduction in the rate at which water and, perhaps, water-soluble low-molecular weight metabolites can enter the cells of the lens nucleus via the epithelium and cortex occurs with a subsequent decrease in the rate of transport of water, nutrients, and antioxidants
- 26. • Consequently, progressive oxidative damage to the lens with aging takes place, leading to senile cataract development. Various studies showing an increase in products of oxidation (eg, oxidized glutathione) and a decrease in antioxidant vitamins and the enzyme superoxide dismutase underscore the important role of oxidative processes in cataractogenesis.
- 27. • Another mechanism involved is the conversion of soluble low- molecular weight cytoplasmic lens proteins to soluble high molecular weight aggregates, insoluble phases, and insoluble membrane protein matrices. The resulting protein changes cause abrupt fluctuations in the refractive index of the lens, scatter light rays, and reduce transparency. • Other areas being investigated include the role of nutrition in cataract development, particularly the involvement of glucose and trace minerals and vitamins.
- 28. • Senile cataract can be classified into 3 main types: • nuclear cataract, cortical cataract, and posterior subcapsular cataract. • Nuclear cataracts result from excessive nuclear sclerosis and yellowing, with consequent formation of a central lenticular opacity. In some instances, the nucleus can become very opaque and brown, termed a brunescent nuclear cataract. • Changes in the ionic composition of the lens cortex and the eventual change in hydration of the lens fibers produce a cortical cataract. • Formation of granular and plaque-like opacities in the posterior subcapsular cortex often heralds the formation of posterior subcapsular cataracts
- 29. • Various culprits have been implicated, including environmental conditions, systemic diseases, UV exposure, diet, and age • cortical and posterior subcapsular cataracts were related closely to environmental stresses, such as UV exposure, diabetes, and drug ingestion. • However, nuclear cataracts seem to have a correlation with smoking. • Alcohol use has been associated with all cataract type
- 30. • cortical cataracts were associated with the presence of diabetes for more than 5 years and increased serum potassium and sodium levels. • A history of surgery under general anesthesia and the use of sedative drugs were associated with reduced risks of senile cortical cataracts. • Posterior subcapsular cataracts were associated with steroid use and diabetes, • while nuclear cataracts had significant correlations with calcitonin and milk intake. • Mixed cataracts were linked with a history of surgery under general anesthesia.
- 31. Other risk factors • Significant associations with senile cataract were noted with increasing age, female sex, social class, and myopia. • prevalence of all cataract types was lower among those with higher education. • Workers exposed to infrared radiation also were found to have a higher incidence of senile cataract development. • Although myopia has been implicated as a risk factor, it was shown that persons with myopia who had worn eyeglasses for at least 20 years underwent cataract extraction at a significantly older age than emmetropes, implying a protective effect of the eyeglasses to solar UV radiation. • The role of nutritional deficiencies in senile cataract has not been proven or established. However, a high intake of the 18-carbon polyunsaturated fatty acids linoleic acid and linolenic acid reportedly may result in an increased risk of developing age-related nuclear opacity. • pseudoexfoliation increased the risk of cataract and subsequent cataract surgery
- 32. Symptoms • Gradual, painless progressive loss of vision • Discomfort / glare in daylight – nuclear cataract; better vision in daylight – cortical cataract • Uniocular polyopia • Coloured halos • Black spots in front of eyes • ‘Second sight’ • Frequent change of glasses
- 33. Signs • Iris shadow • Depth of anterior chamber • Pupillary reflex • Visual acuity • Plain mirror examination under mydriasis
- 34. Signs and symptoms • A patient with senile cataract often presents with a history of gradual progressive visual deterioration and disturbance in night and near vision. • Decreased visual acuity - The most common complaint of patients with senile cataract • Glare - Can range from a decrease in contrast sensitivity in brightly lit environments or disabling glare during the day to glare with oncoming headlights at night • Myopic shift - The progression of cataracts frequently increases the anteroposterior (AP) axis and therefore the diopteric power of the lens, resulting in a mild to moderate degree of increased myopia or myopic shift • Monocular diplopia - At times, the nuclear changes are concentrated in the inner layers of the lens, resulting in a refractile area in the center of the lens, the so called “lens within a lens” phenomenon, which may lead to monocular diplopia that is not correctable with spectacles, prisms, or contact lenses
- 35. Iris shadow A.C. Depth Pupillary reflex Visual acuity Intumescent Present Shallow Greyish white FC to 6/18 Incipient Present Normal Greyish white FC to 6/18 Mature Absent Normal Pearly white HM to FC close to face Hypermature Morgagnian Absent Shallow Milky white HM + Hypermature Calcified Absent Normal or deep Milky chalky HM +
- 36. Patient workup • Retinoscopy and best corrected visual acuity • Intraocular pressure • Slit lamp examination • Fundus evaluation – direct & indirect • Macular function tests • Ultrasonography • IOL power calculation
- 37. Diagnosis • A complete ocular examination must be performed, beginning with visual acuity for near and far distances. • When the patient complains of glare, visual acuity should be tested in a brightly lit room. Contrast sensitivity may also be checked. • Examination of the ocular adnexa and intraocular structures - May provide clues to the patient's cataract etiology, concomitant disease, and eventual visual prognosis • Swinging flashlight test - Detects a Marcus Gunn pupil or a relative afferent pupillary defect (RAPD) indicative of optic nerve lesions or diffuse macular involvement • Slit lamp examination - Should concentrate on the evaluation of not only lens opacity but also other ocular structures (eg, conjunctiva, cornea, iris, anterior chamber) • Examination of nuclear size and brunescence - After dilation, nuclear size and brunescence as indicators of cataract density can be determined prior to phacoemulsification surgery • Direct and indirect ophthalmoscopy - To evaluate the integrity of the posterior pole
- 38. • Ocular imaging studies such as ultrasonography, computed tomography (CT) scanning, or magnetic resonance imaging (MRI) are requested when a significant posterior pole pathology is suspected and an adequate view of the back of the eye is obscured by a dense cataract
- 39. General investigations • Blood pressure • Blood sugar • Complete haemogram • HIV, Hepatitis B & C • Causes of straining • Foci of infection • Systemic examination
- 40. Management • An un-operated eye is more comfortable than an operated eye if visual diminution is mild. • Early cataract : -Refraction and glasses -Dark glasses or photochromatic glasses for nuclear cataract -Rule out other causes of visual diminution -If BCVA not to patient’s satisfaction, then operate.
- 41. Surgical techniques • Intracapsular cataract extraction (ICCE) • Extracapsular cataract extraction (ECCE) – Conventional ECCE – Small Incision Cataract Surgery – Phacoemulsification – Lens aspiration in paediatric (soft) cataract
- 42. Management • Lens extraction is the definitive treatment for senile cataract. It can be accomplished via the following procedures: • Intracapsular cataract extraction (ICCE) - Involves extraction of the entire lens, including the posterior capsule and zonules; the many postoperative complications associated with this procedure has led to a significant decline in its use • Extracapsular cataract extraction (ECCE) - Involves the removal of the lens nucleus through an opening in the anterior capsule and a relatively large limbal incision, with retention of the integrity of the posterior capsule • Phacoemulsification - Also involves extraction of the lens nucleus through an opening in the anterior capsule; an ultrasonically driven needle is used to fragment the nucleus of the cataract; the lens substrate is then aspirated through a needle port via a small limbal or scleral incision in a process termed phacoemulsification Intraocular lens (IOL) implantation is used in combination with each of these techniques, although ECCE and phacoemulsification allow for better anatomical placement of the IOL than does ICCE.
- 43. SRK Formula: Sanders, Retzlaff and Kraff P = A – 0.9 K – 2.5 AL
- 44. Complications of cataract surgery • Intraoperative – Incision related complications – Posterior capsular rupture – Zonular dehisence – Vitreous loss – Nuclear drop – Posterior loss of lens fragments – Injury to the cornea, iris and lens – Expulsive choroidal haemorrhage
- 45. • Early post operative complications – Hyphaema – Iris prolapse – Striate keratopathy – Postoperative anterior uveitis – Bacterial endophthalmitis • Late postoperative complications – Cystoid macular edema – Pseudophakic bullous keraopathy – Retinal detachment – Delayed postoperative endophthalmitis – After cataract • Soemmering’s ring • Elschnig’s pearls
- 46. Intraocular Lenses Types • Anterior chamber IOL • Iris supported lens • Posterior chamber IOL • Rigid • Foldable Calculation of IOL power • SRK formula
- 47. Thank you