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$: Seminar 1 ophthal refractive error and cataract$
REFRECTIVE ERROR AND CATARACTNg Boon Keat, Mohd Hanafi, Anand Kumar

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

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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

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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.


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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

MYOPIA

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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

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CORRECTIONS

» ABC of Eyes, 20048/59

HYPERMETROPIA

• An ocular condition in which only convergent rays can be brought to focus on the retina.

• Synonym:– Hyperopia– Farsightedness


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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


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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

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CORRECTIONS:

» ABC of Eyes, 200412/59

PRESBYOPIA

• The physiologic loss of accommodation in the eyes in advancing age.


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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


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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

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APHAKIA

Clinical features:• Removal of lens will result hypermetropic

refractory error

Corrections:• Glasses• Contact lens• Secondary intraocular lens implant


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INTRAOCULAR LENS IMPLANTS

» ABC of Eyes, 200418/59

CATARACT GLASSES

» ABC of Eyes, 200419/59

ACCOMMODATION


Component of accommodation:

1. Pupil Constriction2. Ciliary muscle

contraction and globular changes of the lens

3. Convergence of the eyes

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PART 2: CATARACT

Anatomical site Cortical NuclearSubcapsular

Anterior SubcapsularPosterior Subcapsular

CATARACT: DEFINITION

Any opacity of the crystalline lensA 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-

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CATARACT: TYPESCataract

DevelopmentalCoronary Lens Opacity

Blue dot Lens Opacity

Dilacerated Lens Opacity

CongenitalNuclear cataract

Lamellar (Zonular) cataract

Anterior and Posterior Polar Cataract

SenileNuclear Sclerosis

Cortical (Cuneiform) Cataract

Subscapsular (Cupuliform) Cataract

2ndary to OcularInflamation, Injury, Glaucoma

With Systemic DiseaseDiabetes Mellitus

Hypoparathyroidism

Galactosemia

Dystropia Myotonica

Down’s Syndrome

Steroid 23/59

CATARACT: DEVELOPMENTAL

Developmental

Coronary Lens Opacity Blue dot Lens Opacity Dilacerated Lens Opacity

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CATARACT: CONGENITALCongenital

Nuclear cataract Lamellar (Zonular) cataract Anterior and Posterior Polar Cataract

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CATARACT: SENILENuclear Sclerosis (Progression)

• Exaggeration of normal nuclear ageing change• Causes increasing myopia

• Increasing nuclear opacification• Initially yellow then brown26/59

CATARACT: SENILE

Senile

Cortical (Cuneiform) Cataract

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CATARACT: SENILESubcapsular (Cupuliform)

Anterior PosteriorMK

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CATARACT: SENILESubcapsular (Cupuliform)

PosteriorMK

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CATARACT: SENILE

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CATARACT: TYPES

Cataract

2ndary to OcularInflamation, Injury, Glaucoma

Prolonged Iritis

Injury: Penetrating and Non-penetratingRetinitis pigmentosa

Phtisis bulbi 31/59

CATARACT: TYPES

Systemic Disease

Diabetes Mellitus Hypoparathyroidism Galactosemia

Systemic Disease

Dystropia Myotonica Down’s Syndrome Steroid

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• White punctate or snowflake posterior or anterior opacities

• May mature within few days

•Cortical and subcapsular opacities• May progress more quickly than in non-diabetics

DIABETES MELLITUS

AdultJuvenile

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Atopic dermatitis

• 90% of patients after age 20 years

• Stellate posterior subcapsular opacity

• No visual problem until age 40 years

• Anterior subcapsular plaque (shield cataract)

Myotonic dystrophy

• Other type – posterior subcapsular

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Causes of traumatic cataract Penetration

Concussion

‘Vossius’ ring from imprinting of iris pigment Flower-shaped

• Ionizing radiation

• Electric shock

• Lightning

Other causes

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CATARACT: AETIOLOGY

Cataract

Acquired

Systemic- Age Related- Drugs- Others

Local (Ocular)

- Trauma- High myopia

- Chronic anterior uveitis

- Topical medical- Intraocular

tumour- Radiation

Congenital

InheritedCongenital infectionSystemic syndromes36/59

CATARACT: SYMPTOMS

Congenital Cataract

• Leukocoria• Squint• Nystagmus• Amblyopia (failure of normal visual development)

Senile / Acquired Cataract

• ↓ visual acuity• Glare• Monocular diplopia and Distortion of lines• Altered colours• Not associated with pain, discharge or redness 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

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TEMPORARY MANAGEMENT

• Not the definitive management• Cannot slow the progression• May in the end have to go for surgery

anyway

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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)

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DEFINITIVE MANAGEMENT

• Extracapsular Cataract Extraction (ECCE)• Phacoemulsification• Intracapsular Cataract Extraction (ICCE)

(All these are followed by intraocular lens implantation)

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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

• CardiovascularHypertension (orbital haemorrhage, suprachoroidal

expulsive haemorrhage)Heart rate (suprachoroidal expulsive haemorrhage)

• Anticoagulant• Posture

difficult if orthopnoea or kyphoscoliosis• Ocular of eye

cornea focusing powerlength

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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

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ECCE

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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 .

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PHACOEMULSIFICATION

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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

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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.

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COMPLICATIONS OF CATARACT SURGERY

1. Operative complications• Vitreous prolapse-may cause retinal detachment• Suprachoroidal (expulsive) haemorrhage2. Early postoperative complications• Iris prolapse• Striate keratopathy• Acute bacterial endophthalmitis-emergency.• Uveitis-prone in pt with DM and previous ocular

inflammtry dx.

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3. Late postoperative complications• Capsular opacification• Implant displacement• Corneal decompensation• Retinal detachment• Chronic bacterial endophthalmitis

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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

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• 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, fibrinous exudate and hypopyon- absent or poor red reflex- inability to visualize fundus with indirect opthalmoscope

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DIFFERENTIAL DIAGNOSIS

1) Uveitis associated with retained lens material - no hypopyon present 2) Sterile fibrinous exudate- no pain and few if any anterior cells- posterior synechiae may develop

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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

MANAGEMENT OF ACUTE ENDOPHTHALMITIS

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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

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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 intravitreal vancomycin- remove IOL and capsular bag if unresponsive

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THANK YOU

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