This document provides information on refractive errors, cataracts, and their treatment. It discusses the types of refractive errors including emmetropia, myopia, hypermetropia, and presbyopia. It describes what causes cataracts, the different types including senile and diabetic cataracts, and symptoms and signs. Treatment options covered include temporary management techniques as well as definitive surgical options like extracapsular cataract extraction and phacoemulsification. Potential complications of cataract surgery and their management are also outlined.

1. REFRECTIVE ERROR AND CATARACT Ng Boon Keat, MohdHanafi, AnandKumar

2. PART 1: REFRECTIVE ERROR

3. EMMETROPIA The state of refraction of the eye in which parallel rays, when the eye is at rest, are focused exactly on the retina. Stedman’s Medical Dictionary, 2005 3/59

4. EMMETROPIA Eye with no refractive error Parellel light = light from infinity (light from far far away) Images are focused with relaxed lens and cornea Without the need for accommodation ABC of Eyes, 2004 4/59

5. MYOPIA That optic condition in which parallel light rays are brought by the ocular media to focus in front of the retina. Synonym: Shortsightedness nearsightedness. Stedman’s Medical Dictionary, 2005 5/59

6. MYOPIA Pathophysiology globe too long relative to refractive mechanisms, or refractive mechanisms too strong light rays from distant object focus in front of retina blurring of distant vision Toronto notes: Ophthalmology, 2006 6/59

7. MYOPIA Clinical features: usually presents in 1st or 2nd decade, stabilizes in 2nd and 3rd decade; rarely begins after 25 years except in diabetes or cataracts blurring of distance vision; near vision usually unaffected Complications: retinal tear/detachment, macular hole, open angle glaucoma. Toronto notes: Ophthalmology, 2006 7/59

9. HYPERMETROPIA An ocular condition in which only convergent rays can be brought to focus on the retina. Synonym: Hyperopia Farsightedness Stedman’s Medical Dictionary, 2005 9/59

10. HYPERMETROPIA Pathophysiology: globe too short relative to refractive mechanisms, or refractive mechanisms too weak light rays from distant object focus behind retina  blurring of near +/-distant vision Toronto notes: Ophthalmology, 2006 10/59

11. HYPERMETROPIA Clinical features: youth: usually do not require glasses (still have sufficient accommodative ability to focus image on retina) 30s-40s: blurring of near vision due to decreased accommodation, may need reading glasses >50s: blurring of distance vision due to severely decreased accommodation Complications: angle-closure glaucoma, particularly later in life as lens enlarges Toronto notes: Ophthalmology, 2006 11/59

13. PRESBYOPIA The physiologic loss of accommodation in the eyes in advancing age. Stedman’s Medical Dictionary, 2005 13/59

14. PRESBYOPIA Pathophysiology hardening/reduced deformability of the lens results in decreased accommodative ability near images cannot be focused onto retina (focus is behind retina as in hyperopia) Normal aging process (especially over 40 years) Toronto notes: Ophthalmology, 2006 14/59

15. PRESBYOPIA Clinical Features: if initially emmetropic, person begins to hold reading material further away, but distance vision remains unaffected if initially myopic, person begins removing distance glasses to read if initially hyperopic, symptoms of presbyopia occur earlier Corrections: Usually as same as treatment of hypermetropia Toronto notes: Ophthalmology, 2006 15/59

16. APHAKIA Absence of the lens of the eye. Stedman’s Medical Dictionary, 2005 A state of having no lens (eg removed because of cataract surgery) Oxford Handbook of Clinical Specialties, 2009 16/59

17. APHAKIA Clinical features: Removal of lens will result hypermetropic refractory error Corrections: Glasses Contact lens Secondary intraocular lens implant ABC of Eyes, 2004 17/59

22. Cortical

23. Nuclear

24. Subcapsular

25. Anterior Subcapsular

27. CATARACT: TYPES 23/59

28. CATARACT: DEVELOPMENTAL 24/59

29. CATARACT: CONGENITAL 25/59

32. Causes increasing myopia26/59

33. CATARACT: SENILE 27/59

34. CATARACT: SENILE MK 28/59

35. CATARACT: SENILE MK 29/59

36. CATARACT: SENILE 30/59

37. CATARACT: TYPES 31/59

38. CATARACT: TYPES 32/59

42. Other type – posterior subcapsular

43. No visual problem until age 40 years34/59

45. Electric shock

46. Lightning35/59

47. CATARACT: AETIOLOGY 36/59

48. CATARACT: SYMPTOMS 37/59

49. CATARACT: SIGNS ↓visual acuity Diminished red reflex Change in lens appearance Normal perception of light Pupillary reflexes normal Slit lamp examination allows the cataract to be examined in detail 38/59

50. TEMPORARY MANAGEMENT Not the definitive management Cannot slow the progression May in the end have to go for surgery anyway 39/59

51. TEMPORARY MANAGEMENT UV blocking sunglasses Change of spectacles correction Instilling dilating drops Anti-oxidant vitamin intake Avoiding smoking - smoking accelerates cataract development Increase lighting especially when reading - illumination from above & behind Routine eye examination - esp. when having certain diseases and taking drugs (eg.steroids, chlorpromazine ) (Only preventive, does not treat cataract) 40/59

52. DEFINITIVE MANAGEMENT Extracapsular Cataract Extraction (ECCE) Phacoemulsification Intracapsular Cataract Extraction (ICCE) (All these are followed by intraocular lens implantation) 41/59

53. INDICATION FOR SURGERY 1) Visual impairment varies from person to person-depends on the location of the opacity. 2) Medical indications presence of cataract adversely affecting health of eye (eg. phacolytic glaucoma, secondary angle closure by an intumescent lens & diabetic retinopathy) 3) Cosmetic indication mature cataract in a blind eye removed to restore a black pupil. 42/59

54. PREOPERATIVE ASSESSMENT Cardiovascular Hypertension (orbital haemorrhage, suprachoroidal expulsive haemorrhage) Heart rate (suprachoroidal expulsive haemorrhage) Anticoagulant Posture difficult if orthopnoea or kyphoscoliosis Ocular of eye cornea focusing power length 43/59

55. EXTRACAPSULAR CATARACT EXTRACTION (ECCE) Incision is made in the eye Anterior capsule is open Nucleus is expressed and soft lens fibres aspirated Non-folding lens is inserted into the lens bag Incision closed with fine sutures 44/59

56. ECCE 45/59

57. PHACOEMULSIFICATION Make a small tunnel incision is made(3 mm) in the eye Circular hole is made in anterior capsule of lens. Ultrasonice probe-liquefy the hard nucleus Remaining soft lens fibre was aspirated A folded replacement lens inserted . 46/59

58. PHACOEMULSIFICATION 47/59

59. INTRACAPSULAR CATARACT EXTRACTION (ICCE) Removal of entire lens together within its capsule with a cryoprobe, suspensory ligaments of the lens have been dissolved ( -chymotrypsin ). bigger incision and slow to heal (around 6 weeks) Higher incident of retinal detachment (vitreous prolapse)and cystoid macular oedema used when facilities for extracapsular surgery are not available. 48/59

60. INTRAOCULAR IMPLANTS Consists of central the lens in position biconvex optic & two legs/haptic to maintain Types of IOL: 1) Polymethylmethacrylate (PMMA) 2) Silicone 49/59

61. INTRAOCULAR IMPLANTS (CONT.) Posterior chamber lens - placed in the empty lens bag. Anterior chamber lens - fixed in the angle of the anterior chamber of the eye. “Pupil clip” lens - clipped to the margin of the iris. 50/59

64. Striate keratopathy

65. Acute bacterial endophthalmitis-emergency.

66. Uveitis-prone in pt with DM and previous ocular inflammtrydx.51/59

68. Implant displacement

69. Corneal decompensation

70. Retinal detachment

71. Chronic bacterial endophthalmitis52/59

72. ACUTE BACTERIAL ENDOPHTHALMITIS incidence - about 1:1,000 common causative organism : Staph. epidermidis,Staph aureus, Pseudomonas sp. Source of infection : - patient’s own external bacterial flora is the most frequent culprit - contaminated solutions and instruments - environmental flora including that of the surgeon and operating room personel 53/59

73. Signs of mild endophthalmitis - mild pain and visual loss - hypopyon in anterior chamber - fundus visible with indirect ophthalmoscope signs of severe endophthalmitis - pain & marked visual loss - corneal haze, fibrinousexudate and hypopyon - absent or poor red reflex - inability to visualize fundus with indirect opthalmoscope 54/59

74. DIFFERENTIAL DIAGNOSIS 1) Uveitis associated with retained lens material - no hypopyon present 2) Sterile fibrinousexudate - no pain and few if any anterior cells - posterior synechiae may develop 55/59

76. Vitreous samples3. Intravitreal injections of antibiotics 4. Vitrectomy – only if VA is PL 5. Subsequent treatment 56/59

78. Steroids only in very severe casesSUBSEQUENT TREATMENT 57/59

79. CHRONIC BACTERIAL ENDOPHTHALMITIS signs: - late onset, persistent, low-grade uveitis- may be granulomatous - commonly caused by P. acnes or Staph. epidermidis - low virulence organisms trapped in capsular bag Rx: - initially good response to topical steroids - recurrence after cessation of treatment - inject intravitrealvancomycin - remove IOL and capsular bag if unresponsive 58/59

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