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Seminar 1 ophthal refractive error and cataract

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    Seminar 1 ophthal   refractive error and cataract Seminar 1 ophthal refractive error and cataract Presentation Transcript

    • REFRECTIVE ERROR AND CATARACT
      Ng Boon Keat, MohdHanafi, AnandKumar
    • PART 1: REFRECTIVE ERROR
    • 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
    • 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
    • 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
    • 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
    • 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
    • CORRECTIONS
      • ABC of Eyes, 2004
      8/59
    • 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
    • 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
    • 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
    • CORRECTIONS:
      • ABC of Eyes, 2004
      12/59
    • PRESBYOPIA
      The physiologic loss of accommodation in the eyes in advancing age.
      Stedman’s Medical Dictionary, 2005
      13/59
    • 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
    • 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
    • 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
    • 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
    • INTRAOCULAR LENS IMPLANTS
      • ABC of Eyes, 2004
      18/59
    • CATARACT GLASSES
      • ABC of Eyes, 2004
      19/59
    • ACCOMMODATION
      • ABC of Eyes, 2004
      Component of accommodation:
      Pupil Constriction
      Ciliary muscle contraction and globular changes of the lens
      Convergence of the eyes
      20/59
    • PART 2: CATARACT
      • Anatomical site
      • Cortical
      • Nuclear
      • Subcapsular
      • Anterior Subcapsular
      • Posterior Subcapsular
    • CATARACT: DEFINITION
      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.
      -WHO-
      Any opacity of the crystalline lens
      22/59
    • CATARACT: TYPES
      23/59
    • CATARACT: DEVELOPMENTAL
      24/59
    • CATARACT: CONGENITAL
      25/59
    • CATARACT: SENILE
      • Increasing nuclear opacification
      • Exaggeration of normal nuclear
      ageing change
      • Initially yellow then brown
      • Causes increasing myopia
      26/59
    • CATARACT: SENILE
      27/59
    • CATARACT: SENILE
      MK
      28/59
    • CATARACT: SENILE
      MK
      29/59
    • CATARACT: SENILE
      30/59
    • CATARACT: TYPES
      31/59
    • CATARACT: TYPES
      32/59
    • Juvenile
      Adult
      • White punctate or snowflake
      posterior or anterior opacities
      • Cortical and subcapsular
      opacities
      • May progress more quickly than
      in non-diabetics
      • May mature within few days
      DIABETES MELLITUS
      33/59
    • Atopic dermatitis
      Myotonic dystrophy
      • Stellate posterior subcapsular opacity
      • Anterior subcapsular plaque
      (shield cataract)
      • 90% of patients after age 20 years
      • Other type – posterior subcapsular
      • No visual problem until age 40 years
      34/59
    • Concussion
      Causes of traumatic cataract
      ‘Vossius’ ring from
      imprinting of iris pigment
      Flower-shaped
      Penetration
      Other causes
      • Ionizing radiation
      • Electric shock
      • Lightning
      35/59
    • CATARACT: AETIOLOGY
      36/59
    • CATARACT: SYMPTOMS
      37/59
    • 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
    • TEMPORARY MANAGEMENT
      Not the definitive management
      Cannot slow the progression
      May in the end have to go for surgery anyway
      39/59
    • 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
    • DEFINITIVE MANAGEMENT
      Extracapsular Cataract Extraction (ECCE)
      Phacoemulsification
      Intracapsular Cataract Extraction (ICCE)
      (All these are followed by intraocular lens implantation)
      41/59
    • 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
    • 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
    • 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
    • ECCE
      45/59
    • 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
    • PHACOEMULSIFICATION
      47/59
    • 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
    • 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
    • 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
    • COMPLICATIONS OF CATARACT SURGERY
      Operative complications
      • Vitreous prolapse-may cause retinal detachment
      • Suprachoroidal (expulsive) haemorrhage
      2. Early postoperative complications
      • Iris prolapse
      • Striate keratopathy
      • Acute bacterial endophthalmitis-emergency.
      • Uveitis-prone in pt with DM and previous ocular inflammtrydx.
      51/59
    • 3. Late postoperative complications
      • Capsular opacification
      • Implant displacement
      • Corneal decompensation
      • Retinal detachment
      • Chronic bacterial endophthalmitis
      52/59
    • 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
    • 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
    • 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
    • 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
      56/59
    • 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
      SUBSEQUENT TREATMENT
      57/59
    • 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
    • THANK YOU