DISEASES OF THE LENS IN CLINICAL EXAMINATION
- 1. DISEASES OF THE LENS OGOT ABUTI MSC MED. MMUST
- 2. Introduction • Cataract is the leading cause of blindness in the world • 20,000,000 people are blind from cataract, including 150-200,000 in Kenya alone • Definition: An opacity of the lens that reduces the vision • A patient with a normal VA cannot have cataract!
- 3. CLASSIFICATION • According to maturity – Immature – Mature – Hypermature – Morgognian • According to anatomical presentation – Anterior and posterior sub capsular – Nucleus – Cortical
- 4. Acquired cataracts Anterior and posterior subcapsular • Lies directly under the lens capsule and is associated with fibrous metaplasia of the lens epithelium. • Posterior subcapsular opacity lies just in front of the posterior capsule and has a vacuolated, granular, or plaque-like appearance on oblique slit-lamp biomicroscopy. • Due to its location at the nodal point of the eye, a posterior subcapsular opacity has a more profound effect on vision than a comparable nuclear or cortical cataract. Near vision is frequently impaired more than distance vision.
- 5. • Patients are particularly troubled under conditions of miosis, such as produced by headlights of oncoming cars and bright sunlight.
- 7. Nucleus cataract • It starts as an exaggeration of the normal ageing changes involving the lens nucleus. • Often associated with myopia due to an increase in the refractive index of the nucleus, and also with increased spherical aberration. • Some elderly patients may consequently be able to read without spectacles • Is characterized in its early stages by a yellowish hue due to the deposition of urochrome pigment.
- 8. • This type of cataract is best assessed with oblique slit-lamp biomicroscopy • When advanced the nucleus appears brown.
- 9. Nuclear cataract • Exaggeration of normal nuclear ageing change • Causes increasing myopia • Increasing nuclear opacification • Initially yellow then brown Progression
- 10. Cortical cataract • It may involve the anterior, posterior or equatorial cortex. The opacities start as clefts and vacuoles between lens fibres due to hydration of the cortex. • Subsequent opacification results in typical cuneiform (wedge-shaped) or radial spoke-like opacities, often initially in the inferonasal quadrant . • Patients with cortical opacities frequently complain of glare due to light scattering.
- 11. Cortical cataract Initially vacuoles and clefts Progressive radial spoke-like opacities Progression
- 12. Christmas tree • Is uncommon, characterized by striking polychromatic needle-like deposits in the deep cortex and nucleus ,they may be solitary or associated with other opacities
- 13. Christmas tree cataract Polychromatic, needle-like opacities May co-exist with other opacities
- 14. Cataract maturity Immature cataract is one in which the lens is partially opaque. Mature cataract is one in which the lens is completely opaque. Hypermature cataract has a shrunken and wrinkled anterior capsule 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.
- 15. Classification according to maturity Immature Mature Hypermature Morgagnian
- 16. Cataract in systemic diseases Diabetes mellitus • Hyperglycaemia is reflected in a high level of glucose in the aqueous humour, which diffuses into the lens. • Here glucose is metabolized by aldose reductase into sorbitol, which then accumulates within the lens, resulting in secondary osmotic overhydration of the lens substance. • In mild degree, this may affect the refractive index of the lens with consequent fluctuation of refraction pari passu with the plasma glucose level (hyperglycaemia resulting in myopia and vice versa). • Cortical fluid vacuoles develop and later evolve into frank opacities.
- 17. Other causes of cataract - diabetes Juvenile • White punctate or snowflake posterior or anterior opacities • May mature within few days Adult • Cortical and subcapsular opacities • May progress more quickly than in non-diabetics
- 18. Other causes of cataract - myotonic dystrophy • Myotonic facies • Frontal balding • 90% of patients after age 20 years • Stellate posterior subcapsular opacity • No visual problem until age 40 years
- 19. Other causes of cataract - atopic dermatitis • Cataract develops in 10% of cases between 15-30 years • Bilateral in 70% • Frequently becomes mature • Anterior subcapsular plaque (shield cataract) • Wrinkles in anterior capsule
- 20. Secondary cataract • A secondary (complicated) cataract develops as a result of some other primary ocular disease. Chronic uveitis • Is the most common cause. The incidence is related to the duration and activity of intraocular inflammation that results in prolonged breakdown of the blood–aqueous and/or blood–vitreous barrier. • The use of steroids, topically and systemically, is also important.
- 21. Cont- • Acute congestive closure glaucoma • High myopia • Hereditary fundus dystrophy
- 22. Secondary (complicated) cataract • Chronic anterior uveitis • High myopia Posterior subcapsular • Hereditary fundus dystrophies • Central, anterior subcapsular opacities Glaukomflecken • Follows acute angle- closure glaucoma
- 23. Traumatic cataract • Trauma is the most common cause of unilateral cataract in young individuals and may include the following. 1 Penetrating trauma 2 Blunt trauma may cause a characteristic flower-shaped opacity 3 Electric shock and lightning strike are very rare causes that may result in anterior and posterior iridescent opacities that have a stellate pattern. 4 Infrared radiation, if intense as in glassblowers, may rarely cause true exfoliation of the anterior lens capsule . 5Ionizing radiation for ocular tumours may cause posterior subcapsular opacities that may develop months or years later.
- 24. • Penetrating injury causing a ruptured lens. Traumatic cataracts
- 25. Management of cataracts/ age related cataract • Preoperative consideration • Indication of surgery • Visual improvement is by far the most common indication for cataract surgery. Operation is indicated only if and when the opacity develops to a degree sufficient to cause difficulty in performing essential daily activities. • Medical indications are those in which a cataract is adversely affecting the health of the eye, for example, phacolytic or phacomorphic glaucoma. • Systemic preoperative assessment -reading assignment
- 26. cont- Ophthalmic preoperative assessment -Visual acuity -Cover test -Pupillary response -Ocular adnexia -Anterior chamber -Lens -Fundus -Current refractive status
- 27. Reading assignment • Biometry • Intraocular lenses • Phaco- emulsification
- 28. Anaesthesia • The vast majority of cataract surgery is performed under local anaesthesia (LA) although general anaesthesia is required in some circumstances such as children and many young adults, very anxious patients, some patients with learning difficulties, epilepsy, dementia and those with a head tremor
- 29. • Sub-Tenon block involves inserting a blunt-tipped cannula through an incision in the conjunctiva and Tenon capsule 5 mm from the limbus inferonasally, and passing it through the sub-Tenon space. The anaesthetic is injected beyond the equator of the globe. • Peribulbar block is given through the skin or conjunctiva with a 1-inch (25-mm) needle. It generally provides effective anaesthesia and akinesia.
- 30. • Topical anaesthesia involves drops or gel (proxymetacaine 0.5%, tetracaine 1% drops, lidocaine 2% gel) which can be augmented with intracameral preservative-free lidocaine 0.2%–1%, usually during hydrodissection; combined viscoelastic/lidocaine preparations are also commercially available.
- 31. Small incision cataract surgery • Is an effective alternative to phacoemulsification in countries where very high volume surgery with inexpensive instrumentation is required. • The procedure is fast and has a low rate of complications, and can be performed on a dense cataract.
- 32. • A self-sealing partial thickness scleral tunnel is dissected and the anterior chamber is entered • Capsulorhexis is performed • Hydrodissection is performed and the nucleus is partly prolapsed into the anterior chamber • A small hook is inserted between the posterior capsule and nucleus, and the nucleus extracted It is also possible to extract the nucleus with an irrigating vectis.
- 33. • The epinucleus and residual cortex are aspirated with a Simcoe cannula • The IOL is inserted
- 34. Extracapsular cataract extraction 1. Anterior capsulotomy 2. Completion of incision 3. Expression of nucleus 4. Cortical cleanup 6. Polishing of posterior capsule, if appropriate 5. Care not to aspirate posterior capsule accidentally
- 35. 8. Grasping of IOL and coating with viscoelasti substance Extracapsular cataract extraction ( cont. ) 7. Injection of viscoelastic substance 9. Insertion of inferior haptic and optic 11. Placement of haptics into capsular bag 10. Insertion of superior haptic 12. Dialling of IOL into horizontal position and not into ciliary sulcus
- 36. Congenital cataract • Occur in about 3 in 10 000 live births. Two-thirds of cases are bilateral and the cause can be identified in about half of those affected. • The most common cause is genetic mutation, usually autosomal dominant (AD); other causes include chromosomal abnormalities, metabolic disorders and intrauterine infections. • Unilateral cataracts are usually sporadic, without a family history or systemic disease, and affected infants are usually full-term and healthy.
- 37. Complications of cataract surgery • Vitreous loss 1. Operative complications • Posterior loss of lens fragments • Suprachoroidal (expulsive) haemorrhage • Iris prolapse • Striate keratopathy • Acute bacterial endophthalmitis 2. Early postoperative complications 3. Late postoperative complications • Capsular opacification • Implant displacement • Corneal decompensation • Retinal detachment • Chronic bacterial endophthalmitis
- 38. Operative complications of vitreous loss Sponge or automated anterior vitrectomy Management Insertion of PC-IOL if adequate casular support present
- 39. Insertion of AC-IOL If adequate capsular support absent 2. Peripheral iridectomy 3. Glide insertion 4. Coating of IOL with viscoelastic substance 5. Insertion of IOL 6. Suturing of incision 1. Constriction of pupil
- 40. Management of posterior loss of lens fragmen Fragments consisting of 25% or more of lens should be removed Pars plana vitrectomy and removal of fragment
- 41. Management of suprachoroidal (expulsive) haemorrhage Close incision and administer hyperosmotic agent • Drain blood • Pars plana vitrectomy • Air-fluid exchange Subsequent treatment after 7-14 days
- 42. Early postoperative complications Cause • Usually inadequate suturing of incision • Most frequently follows inappropriate management of vitreous loss • Excise prolapsed iris tissue • Resuture incision Treatment Iris prolapse
- 43. Striate keratopathy Corneal oedema and folds in Descemet membrane Cause • Damage to endothelium during surgery Treatment • Most cases resolve within a few days • Occasionally persistent cases may require penetrating keratoplasty
- 44. Acute bacterial endophthalmitis Common causative organisms • Staph. epidermidis • Staph. aureus • Pseudomonas sp. Incidence - about 1:1,000 • Patient’s own external bacterial flora is most frequent culprit Source of infection • Contaminated solutions and instruments • Environmental flora including that of surgeon and operating room personnel
- 45. Preoperative prophylaxis Staphylococcal blepharitis Chronic conjunctivitis Chronic dacryocystitis Infected socket Treatment of pre-existing infections
- 46. Peroperative prophylaxis Instillation of povidone-iodine Postoperative injection of antibiotics Meticulous prepping and draping
- 47. Signs of severe endophthalmitis • Pain and marked visual loss • Absent or poor red reflex • Corneal haze, fibrinous exudate and hypopyon • Inability to visualize fundus with indirect ophthalmoscope
- 48. Signs of mild endophthalmitis • Mild pain and visual loss • Anterior chamber cells • Small hypopyon • Fundus visible with indirect ophthalmoscope
- 49. Differential diagnosis of endophthalmitis • No pain or hypopyon Uveitis associated with retained lens material • No pain and few if any anterior cells Sterile fibrinous reaction • Posterior synechiae may develop
- 50. Management of Acute Endophthalmitis 1. Preparation of intravitreal injections 2. Identification of causative organisms • Aqueous samples • Vitreous samples 3. Intravitreal injections of antibiotics 4. Vitrectomy - only if VA is PL 5. Subsequent treatment
- 51. Preparation for sampling and injections Antibiotics Mini vitrector
- 52. Sampling and injections (1) Make partial-thickness sclerotomy 3 mm behind limbus Insert mini vitrector
- 53. Sampling and injections ( 2 ) • Aspirate 0.3 ml with vitrector • Give first injection of antibiotics • Disconnect syringe from needle • Give second injection • Remove vitrector and needle • Inject subconjunctival antibiotics • Insert needle attached to syringe containing antibiotics
- 54. Subsequent Treatment 1. Periocular injections • Vancomycin 25 mg with ceftazidime 100 mg or gentamicin 20 mg with cefuroxime 125 mg • Betamethasone 4 mg (1 ml) 2. Topical therapy • Fortified gentamicin 15 mg/ml and vancomycin 50 mg/ml drops • Dexamethasone 0.1% 3. Systemic therapy • Antibiotics are not beneficial • Steroids only in very severe cases
- 55. Types of capsular opacification Elschnig pearls • Proliferation of lens epithelium • Occurs after 3-5 years • Usually occurs within 2-6 months • May involve remnants of anterior capsule and cause phimosis Fibrosis
- 56. Treatment of capsular opacification Nd:YAG laser capsulotomy • Accurate focusing is vital • Apply series of punctures in cruciate pattern (a-c) • 3 mm opening is adequate (d) • Damage to implant Potential complications • Cystoid macular oedema - uncommon • Retinal detachment - rare except in high myopes
- 57. Implant displacement Decentration • May occur if one haptic is inserted into sulcus and other into bag • Reposition may be necessary • Remove and replace if severe Optic capture
- 58. Corneal decompensation • Anterior chamber implant • Fuchs endothelial dystrophy • Penetrating keratoplasty in severe cases • Guarded visual prognosis because of frequently associated CMO Treatment Predispositions
- 59. Retinal detachment risk factors Disruption of posterior capsule • Intraoperative vitreous loss • Laser capsulotomy, particularly in high myopia • Treat prophylactically before or soon after surgery Lattice degeneration
- 60. Chronic bacterial endophthalmitis • Low virulence organisms trapped in capsular bag • Late onset, persistent, low-grade uveitis - may be granulomatous • White plaque on posterior capsule • Commonly caused by P. acnes or Staph. epidermidis Signs
- 61. Treatment of chronic endophthalmitis • Initially good response to topical steroids • Recurrence after cessation of treatment • Inject intravitreal vancomycin • Remove IOL and capsular bag if unresponsive
- 62. Congenital cataract-aetiology • Occur in about 3 in 10 000 live births. Two-thirds of cases are bilateral and the cause can be identified in about half of those affected. • The most common cause is genetic mutation, usually autosomal dominant (AD); other causes include chromosomal abnormalities, metabolic disorders and intrauterine infections. • Unilateral cataracts are usually sporadic, without a family history or systemic disease, and affected infants are usually full-term and healthy.
- 63. Cont-Inheritance • Isolated hereditary cataracts account for about 25% of cases. The mode is most frequently AD but may be autosomal recessive (AR) or X-linked (X-L). • The morphology of the opacities and frequently the need for surgery are usually similar in parent and offspring. • Isolated inherited congenital cataracts carry a better visual prognosis than those with coexisting ocular and systemic abnormalities.
- 64. Morphology • Is important because it may indicate a likely aetiology, mode of inheritance and effects on vision. – Nuclear opacities are confined to the embryonic or foetal nuclei of the lens. The cataract may be dense or composed of fine pulverulent (dust-like) opacities . – They may be associated with microphthalmos – Lamellar opacities affect a particular lamella of the lens both anteriorly and posteriorly and in some cases is associated with radial extensions . – Opacities occur in isolation as well as in infants with metabolic disorders and intrauterine infections.
- 65. • Coronary (supranuclear) cataract lies in the deep cortex and surrounds the nucleus like a crown. • They are usually sporadic and only occasionally hereditary. • Blue dot opacities (cataracta punctata caerulea) are common and innocuous, and may coexist with other types of lens opacity • Sutural in which the opacity follows the anterior or posterior Y suture. It may occur in isolation or in association with other opacities.
- 66. • Anterior polar cataract may be flat or project as a conical opacity into the anterior chamber (pyramidal cataract. • Occasional associations of anterior polar cataracts include persistent pupillary membrane, aniridia, Peters anomaly and anterior lenticonus. • Posterior polar cataract may be occasionally associated with persistent hyaloid remnants (Mittendorf dot), posterior lenticonus and persistent hyperplastic primary vitreous.
- 67. Classification of congenital cataract Anterior polar Posterior polar Coronary Cortical spoke-like Lamellar Central pulverulent Sutural Focal dots
- 68. Systemic metabolic associations • Galactocemia • Lowe syndrome • Fabry disease • Mannosidosis • Reading assignment
- 69. Causes of cataract in unwell neonate Intrauterine infections • Rubella • Toxoplasmosis • Cytomegalovirus • Varicella Metabolic disorders • Galactosaemia • Hypoglycaemia • Hypocalcaemia • Lowe syndrome
- 70. Associated intrauterine infections • Congenital rubella- • Results from transplacental transmission of virus to the fetus from an infected mother, usually during the first trimester of pregnancy that may lead to serious chronic fetal infection and malformations. • The risk to the fetus is closely related to the stage of gestation at the time of maternal infection. • Fetal infection is about 50% during the first 8 weeks, 33% between weeks 9 and 12, and about 10% between weeks 13 and 24.
- 71. • Systemic features include spontaneous abortion, stillbirth, congenital heart malformations, deafness, microcephaly, mental handicap, hypotonia, hepatosplenomegaly, thrombocytopenic purpura, pneumonitis, myocarditis and metaphyseal bone lesions. • Ocular features – Cataract occur in 15% of cases, – The opacity may affect the nucleus – The virus is capable of persisting in the lenses for three years after birth
- 72. • Toxoplasmosis • Systemic features include seizures, hydrocephalus, microcephaly, hepatosplenomegaly, deafness and intracranial calcification • Ocular features apart from cataract include chorioretinitis, microphthalmos and optic atrophy
- 73. • Cytomegallovirus infection • Systemic features include jaundice, hepatosplenomegaly, microcephaly and intracranial calcification. • Ocular features apart from cataract include chorioretinitis, microphthalmos, keratitis and optic atrophy.
- 74. • Varicella • Systemic features include mental handicap, cortical cerebral atrophy, cutaneous scarring and limb deformities; death in early infancy is common. • Ocular features apart from cataract include microphthalmos, Horner syndrome, chorioretinitis, optic disc hypoplasia and optic atrophy.
- 75. Management • Systemic investigation – Serology for intrauterine infections – Urine. Urinalysis for reducing substance after drinking milk (galactosaemia) and chromatography for amino acids (Lowe syndrome – Other investigations include fasting blood glucose, serum calcium and phosphorus, red blood cell GPUT and galactokinase levels – Referral to a paediatrician may be warranted for dysmorphic features or suspicion of other systemic diseases.
- 76. • Treatment • Bilateral dense cataracts require early surgery when the child is 4–6 weeks of age to prevent the development of stimulus deprivation amblyopia. • Bilateral partial cataracts may not require surgery until later. • Unilateral dense cataract merits urgent surgery (possibly within days) followed by aggressive anti- amblyopia therapy, despite which the results are often poor.
- 77. • Partial unilateral cataract can usually be observed or treated non-surgically with pupillary dilatation and possibly part time contralateral occlusion to prevent amblyopia. • Surgery involves anterior capsulorhexis, aspiration of lens matter, capsulorhexis of the posterior capsule, limited anterior vitrectomy and IOL implantation, if appropriate. • It is important to correct associated refractive errors.
- 78. Complications • Posterior capsular opacification • Secondary membranes • Proliferation of lens epithelium • Glaucoma • Retinal detachment
- 79. Visual rehabilitation • Spectacles are useful for older children with bilateral aphakia. • Contact lenses provide a superior optical solution for both unilateral and bilateral aphakia. • IOL implantation is increasingly being performed in younger children and appears to be effective and safe in selected cases. • Occlusion to treat or prevent amblyopia is essential.
- 80. ECTOPIA LENTIS 1. Acquired 2. Isolated familial ectopia lentis 3. Associated with systemic syndromes • Marfan syndrome • Weill-Marchesani syndrome • Homocystinuria 4. Treatment options
- 81. Isolated familial ectopia lentis Autosomal recessive Pupil may be normal Pupil may be displaced in opposite direction (ectopia lentis et pupillae)
- 82. Autosomal dominant Systemic features of Marfan syndrome • Limb-trunk disproportion • Arachnodactyly • Pectus excavatum • High-arched palate • Aortic dilatation, dissection and regurgitation • Mitral valve prolapse
- 83. Ocular features of Marfan syndrome Lens • Upward subluxation • Zonule usually intact Retinal detachment • Axial myopia Blue sclera Cornea plana Angle anomaly and glaucoma • Lattice degeneration
- 84. Treatment Options for Ectopia Lentis • For induced astigmatism 1. Spectacle correction • For aphakic portion • Associated cataract 3. Surgical removal • Lens-induced glaucoma 2. Nd:YAG laser zonulysis to displace lens out of visual axis • Endothelial touch • When other methods are inappropriate
- 85. ABNORMALITIES OF LENS SHAPE 2. Lenticonus 1. Coloboma 3. Small lens
- 86. Coloboma Coloboma of iris Coloboma of choroid Giant retinal tear Ocular associations
- 87. Lenticonus Posterior • Posterior axial bulge • Unilateral - usually sporadic • Bilateral - familial or in Lowe syndrome Anterior • Anterior axial bulge • Associated with Alport syndrome
- 88. Small lens • Small diameter • Small diameter and spherical • May be familial (dominant) Microphakia Microspherophakia • Systemic association - Lowe syndrome • Systemic association - Weill-Marchesani syndrome