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Ophthal refractive error and cataract


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Ophthal refractive error and cataract

  1. 1. REFRECTIVE ERROR AND CATARACT<br />Ng Boon Keat, MohdHanafi, AnandKumar<br />
  2. 2. PART 1: REFRECTIVE ERROR<br />
  3. 3. EMMETROPIA<br />The state of refraction of the eye in which parallel rays, when the eye is at rest, are focused exactly on the retina.<br />Stedman’s Medical Dictionary, 2005<br />3/59<br />
  4. 4. EMMETROPIA<br />Eye with no refractive error<br />Parellel light = light from infinity (light from far far away)<br />Images are focused with relaxed lens and cornea<br />Without the need for accommodation<br />ABC of Eyes, 2004<br />4/59<br />
  5. 5. MYOPIA<br />That optic condition in which parallel light rays are brought by the ocular media to focus in front of the retina. <br />Synonym: <br />Shortsightedness<br />nearsightedness.<br />Stedman’s Medical Dictionary, 2005<br />5/59<br />
  6. 6. MYOPIA<br />Pathophysiology<br />globe too long relative to refractive mechanisms, or refractive mechanisms too strong <br />light rays from distant object focus in front of retina blurring of distant vision <br />Toronto notes: Ophthalmology, 2006<br />6/59<br />
  7. 7. MYOPIA<br />Clinical features:<br />usually presents in 1st or 2nd decade, stabilizes in 2nd and 3rd decade; rarely begins after 25 years except in diabetes or cataracts<br />blurring of distance vision; near vision usually unaffected <br />Complications:<br />retinal tear/detachment, macular hole, open angle glaucoma. <br />Toronto notes: Ophthalmology, 2006<br />7/59<br />
  8. 8. CORRECTIONS<br /><ul><li>ABC of Eyes, 2004</li></ul>8/59<br />
  9. 9. HYPERMETROPIA<br />An ocular condition in which only convergent rays can be brought to focus on the retina. <br />Synonym:<br />Hyperopia<br />Farsightedness<br />Stedman’s Medical Dictionary, 2005<br />9/59<br />
  10. 10. HYPERMETROPIA<br />Pathophysiology:<br />globe too short relative to refractive mechanisms, or refractive mechanisms too weak<br />light rays from distant object focus behind retina  blurring of near +/-distant vision<br />Toronto notes: Ophthalmology, 2006<br />10/59<br />
  11. 11. HYPERMETROPIA<br />Clinical features: <br />youth: usually do not require glasses (still have sufficient accommodative ability to focus image on retina)<br />30s-40s: blurring of near vision due to decreased accommodation, may need reading glasses<br />>50s: blurring of distance vision due to severely decreased accommodation <br />Complications:<br />angle-closure glaucoma, particularly later in life as lens enlarges<br />Toronto notes: Ophthalmology, 2006<br />11/59<br />
  12. 12. CORRECTIONS:<br /><ul><li>ABC of Eyes, 2004</li></ul>12/59<br />
  13. 13. PRESBYOPIA<br />The physiologic loss of accommodation in the eyes in advancing age.<br />Stedman’s Medical Dictionary, 2005<br />13/59<br />
  14. 14. PRESBYOPIA<br />Pathophysiology<br />hardening/reduced deformability of the lens results in decreased accommodative ability <br />near images cannot be focused onto retina (focus is behind retina as in hyperopia) <br />Normal aging process (especially over 40 years) <br />Toronto notes: Ophthalmology, 2006<br />14/59<br />
  15. 15. PRESBYOPIA<br />Clinical Features: <br />if initially emmetropic, person begins to hold reading material further away, but distance vision remains unaffected <br />if initially myopic, person begins removing distance glasses to read <br />if initially hyperopic, symptoms of presbyopia occur earlier <br />Corrections:<br />Usually as same as treatment of hypermetropia<br />Toronto notes: Ophthalmology, 2006<br />15/59<br />
  16. 16. APHAKIA<br />Absence of the lens of the eye.<br />Stedman’s Medical Dictionary, 2005<br />A state of having no lens (eg removed because of cataract surgery)<br />Oxford Handbook of Clinical Specialties, 2009<br />16/59<br />
  17. 17. APHAKIA<br />Clinical features:<br />Removal of lens will result hypermetropic refractory error<br />Corrections:<br />Glasses<br />Contact lens<br />Secondary intraocular lens implant<br />ABC of Eyes, 2004<br />17/59<br />
  18. 18. INTRAOCULAR LENS IMPLANTS<br /><ul><li>ABC of Eyes, 2004</li></ul>18/59<br />
  19. 19. CATARACT GLASSES<br /><ul><li>ABC of Eyes, 2004</li></ul>19/59<br />
  20. 20. ACCOMMODATION<br /><ul><li>ABC of Eyes, 2004</li></ul>Component of accommodation:<br />Pupil Constriction<br />Ciliary muscle contraction and globular changes of the lens<br />Convergence of the eyes<br />20/59<br />
  21. 21. PART 2: CATARACT<br /><ul><li>Anatomical site
  22. 22. Cortical
  23. 23. Nuclear
  24. 24. Subcapsular
  25. 25. Anterior Subcapsular
  26. 26. Posterior Subcapsular</li></li></ul><li>CATARACT: DEFINITION<br />A cataract is clouding of the lens of the eye, which impedes the passage of light. Most cataracts are related to ageing, although occasionally children may be born with the condition, or cataract may develop after an injury, inflammation or disease.<br />-WHO-<br />Any opacity of the crystalline lens<br />22/59<br />
  27. 27. CATARACT: TYPES<br />23/59<br />
  28. 28. CATARACT: DEVELOPMENTAL<br />24/59<br />
  29. 29. CATARACT: CONGENITAL<br />25/59<br />
  30. 30. CATARACT: SENILE<br /><ul><li> Increasing nuclear opacification
  31. 31. Exaggeration of normal nuclear</li></ul> ageing change<br /><ul><li> Initially yellow then brown
  32. 32. Causes increasing myopia</li></ul>26/59<br />
  33. 33. CATARACT: SENILE<br />27/59<br />
  34. 34. CATARACT: SENILE<br />MK<br />28/59<br />
  35. 35. CATARACT: SENILE<br />MK<br />29/59<br />
  36. 36. CATARACT: SENILE<br />30/59<br />
  37. 37. CATARACT: TYPES<br />31/59<br />
  38. 38. CATARACT: TYPES<br />32/59<br />
  39. 39. Juvenile<br />Adult<br /><ul><li>White punctate or snowflake</li></ul> posterior or anterior opacities<br /><ul><li>Cortical and subcapsular</li></ul> opacities<br /><ul><li>May progress more quickly than</li></ul> in non-diabetics<br /><ul><li>May mature within few days</li></ul>DIABETES MELLITUS<br />33/59<br />
  40. 40. Atopic dermatitis<br />Myotonic dystrophy<br /><ul><li> Stellate posterior subcapsular opacity
  41. 41. Anterior subcapsular plaque</li></ul> (shield cataract)<br /><ul><li> 90% of patients after age 20 years
  42. 42. Other type – posterior subcapsular
  43. 43. No visual problem until age 40 years</li></ul>34/59<br />
  44. 44. Concussion <br />Causes of traumatic cataract<br /> ‘Vossius’ ring from<br /> imprinting of iris pigment<br />Flower-shaped<br />Penetration<br />Other causes <br /><ul><li> Ionizing radiation
  45. 45. Electric shock
  46. 46. Lightning</li></ul>35/59<br />
  47. 47. CATARACT: AETIOLOGY<br />36/59<br />
  48. 48. CATARACT: SYMPTOMS<br />37/59<br />
  49. 49. CATARACT: SIGNS<br />↓visual acuity<br />Diminished red reflex <br />Change in lens appearance<br />Normal perception of light<br />Pupillary reflexes normal<br />Slit lamp examination allows the cataract to be examined in detail<br />38/59<br />
  50. 50. TEMPORARY MANAGEMENT<br />Not the definitive management<br />Cannot slow the progression<br />May in the end have to go for surgery anyway<br />39/59<br />
  51. 51. TEMPORARY MANAGEMENT<br />UV blocking sunglasses<br />Change of spectacles correction<br />Instilling dilating drops<br />Anti-oxidant vitamin intake<br />Avoiding smoking - smoking accelerates cataract development<br />Increase lighting especially when reading - illumination from above & behind<br />Routine eye examination - esp. when having certain diseases and taking drugs (eg.steroids, chlorpromazine )<br />(Only preventive, does not treat cataract)<br />40/59<br />
  52. 52. DEFINITIVE MANAGEMENT<br />Extracapsular Cataract Extraction (ECCE)<br />Phacoemulsification<br />Intracapsular Cataract Extraction (ICCE)<br />(All these are followed by intraocular lens implantation)<br />41/59<br />
  53. 53. INDICATION FOR SURGERY<br />1) Visual impairment<br />varies from person to person-depends on the location of the opacity.<br />2) Medical indications<br />presence of cataract adversely affecting health of eye (eg. phacolytic glaucoma, secondary angle closure by an intumescent lens & diabetic retinopathy)<br />3) Cosmetic indication<br />mature cataract in a blind eye removed to restore a black pupil.<br />42/59<br />
  54. 54. PREOPERATIVE ASSESSMENT<br />Cardiovascular<br />Hypertension (orbital haemorrhage, suprachoroidal expulsive haemorrhage)<br />Heart rate (suprachoroidal expulsive haemorrhage)<br />Anticoagulant<br />Posture<br /> difficult if orthopnoea or kyphoscoliosis<br />Ocular of eye<br /> cornea focusing power<br /> length<br />43/59<br />
  55. 55. EXTRACAPSULAR CATARACT EXTRACTION (ECCE)<br />Incision is made in the eye<br />Anterior capsule is open<br />Nucleus is expressed and soft lens fibres aspirated<br />Non-folding lens is inserted into the lens bag<br />Incision closed with fine sutures<br />44/59<br />
  56. 56. ECCE<br />45/59<br />
  57. 57. PHACOEMULSIFICATION<br />Make a small tunnel incision is made(3 mm) in the eye<br />Circular hole is made in anterior capsule of lens.<br />Ultrasonice probe-liquefy the hard nucleus<br />Remaining soft lens fibre was aspirated<br />A folded replacement lens inserted .<br />46/59<br />
  58. 58. PHACOEMULSIFICATION<br />47/59<br />
  59. 59. INTRACAPSULAR CATARACT EXTRACTION (ICCE)<br />Removal of entire lens together within its capsule with a cryoprobe,<br />suspensory ligaments of the lens have been dissolved ( -chymotrypsin ).<br />bigger incision and slow to heal (around 6 weeks)<br />Higher incident of retinal detachment (vitreous prolapse)and cystoid macular oedema<br />used when facilities for extracapsular surgery are not available.<br />48/59<br />
  60. 60. INTRAOCULAR IMPLANTS<br />Consists of central the lens in position biconvex optic & two legs/haptic to maintain <br />Types of IOL:<br /> 1) Polymethylmethacrylate<br /> (PMMA)<br /> 2) Silicone<br />49/59<br />
  61. 61. INTRAOCULAR IMPLANTS (CONT.)<br />Posterior chamber lens - placed in the empty lens bag.<br />Anterior chamber lens - fixed in the angle of the anterior chamber of the eye.<br />“Pupil clip” lens - clipped to the margin of the iris.<br />50/59<br />
  62. 62. COMPLICATIONS OF CATARACT SURGERY<br />Operative complications<br /><ul><li>Vitreous prolapse-may cause retinal detachment
  63. 63. Suprachoroidal (expulsive) haemorrhage</li></ul>2. Early postoperative complications<br /><ul><li>Iris prolapse
  64. 64. Striate keratopathy
  65. 65. Acute bacterial endophthalmitis-emergency.
  66. 66. Uveitis-prone in pt with DM and previous ocular inflammtrydx.</li></ul>51/59<br />
  67. 67. 3. Late postoperative complications<br /><ul><li>Capsular opacification
  68. 68. Implant displacement
  69. 69. Corneal decompensation
  70. 70. Retinal detachment
  71. 71. Chronic bacterial endophthalmitis</li></ul>52/59<br />
  72. 72. ACUTE BACTERIAL ENDOPHTHALMITIS<br />incidence - about 1:1,000<br />common causative organism : Staph. epidermidis,Staph aureus, Pseudomonas sp.<br />Source of infection :<br /> - patient’s own external bacterial flora is the most frequent culprit<br /> - contaminated solutions and instruments<br /> - environmental flora including that of the surgeon and operating room personel<br />53/59<br />
  73. 73. Signs of mild endophthalmitis<br /> - mild pain and visual loss<br /> - hypopyon in anterior chamber <br /> - fundus visible with indirect ophthalmoscope<br />signs of severe endophthalmitis<br /> - pain & marked visual loss<br /> - corneal haze, fibrinousexudate and hypopyon<br /> - absent or poor red reflex<br /> - inability to visualize fundus with indirect opthalmoscope<br />54/59<br />
  74. 74. DIFFERENTIAL DIAGNOSIS<br /> 1) Uveitis associated with retained lens material<br /> - no hypopyon present <br /> 2) Sterile fibrinousexudate<br /> - no pain and few if any anterior cells<br /> - posterior synechiae may develop<br />55/59<br />
  75. 75. MANAGEMENT OF ACUTE ENDOPHTHALMITIS<br />1. Preparation of intravitreal injections<br />2. Identification of causative organisms<br /><ul><li> Aqueous samples
  76. 76. Vitreous samples</li></ul>3. Intravitreal injections of antibiotics<br />4. Vitrectomy – only if VA is PL<br />5. Subsequent treatment<br />56/59<br />
  77. 77. 1. Periocular injections<br /><ul><li> Vancomycin 25 mg with ceftazidime 100 mg </li></ul> or gentamicin 20 mg with cefuroxime 125 mg<br /><ul><li>Betamethasone 4 mg (1 ml)</li></ul>2. Topical therapy<br /><ul><li> Fortified gentamicin 15 mg/ml and vancomycin 50 mg/ml</li></ul> drops<br /><ul><li> Dexamethasone 0.1%</li></ul>3. Systemic therapy<br /><ul><li> Antibiotics are not beneficial
  78. 78. Steroids only in very severe cases</li></ul>SUBSEQUENT TREATMENT<br />57/59<br />
  79. 79. CHRONIC BACTERIAL ENDOPHTHALMITIS<br />signs:<br /> - late onset, persistent, low-grade uveitis- may be granulomatous<br /> - commonly caused by P. acnes or Staph. epidermidis<br /> - low virulence organisms trapped in capsular bag<br />Rx:<br /> - initially good response to topical steroids<br /> - recurrence after cessation of treatment<br /> - inject intravitrealvancomycin<br /> - remove IOL and capsular bag if unresponsive<br />58/59<br />
  80. 80. THANK YOU<br />