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Extra eye > Lens and cataracts > Flashcards

Lens and cataracts Flashcards

1
Q

Lens capsule antioxdiants

A

contains glutathione and ascorbic acid

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2
Q

Lens capsule posterior

A

Thinnest
Doesnt thicken with age

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3
Q

Lens capsule anterior

A

Thickens with age

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4
Q

Lens capsule content

A

Collagen 4

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5
Q

Lens epithelium

A

single cuboidal cell layer
only found below anterior capsule
periphery - mitotic
central - non-mitotic

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6
Q

Lens sutures

A

Anteriro Y
Posterior inverted Y

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7
Q

Lens ultrastructure

A

Nucleus (old fibres)
Cortex (new fibres)

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8
Q

Cataract grades

A

Immature - partially opaque
Mature - completely opague
Hypermature - cataract material leaking, shrunk and winkly anterior capsule
Morgagnian cataract - cortex had liquified and nucleus has sunk in it

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9
Q

Age related Cataract types

A

Nuclear - centre yellow, myopic shift! near vision improves

Cortical - wedge shaped opacity, glare at night with bright lights

Subcapsular - anterior (blunt trauma), posterior (diabetes, chloroquine, steroids, retinitis pigmentosa, NF)

Polychromatic (christmas tree) - needle like opacities in nucleus and deep cortex

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10
Q

Cataract associations:

Anterior subcapsular
Blue dot
Pearly nuclear
Sunflower
Shield like
Christmas tree

A

Anterior subcapsular - blunt trauma
Blue dot - down syndrome
Pearly nuclear - Rubella
Sunflower - Wilson’s disease
Shield like - Atopic dermatitis
Christmas tree - myotonic dystrophy

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11
Q

Congenital cataracts

A

Autosomal dominant, also due to homocystinuria and Down syndrome

Unilateral - remove at 6 weeks
Bilateral - remove at 10 weeks

Weigh risk between glaucoma and amblyopia

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12
Q

Biometry

A

Calculating IOL power - IOLmaster

Parameters:
Axial length of the eye, corneal curvature, anterior chamber depth

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13
Q

Types of IOL

A

Rigid - PMMA, not widely used

Soft -
1. Silicon - not used
2. Acrylic hydrophobic - less risk of PCO but glare
3. Acrlylic hydrophilic - high biocompatibility but risk of PCO

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14
Q

Techniques of cataract surgery

A
  1. Phacoemulsification (gold standard) - US needle
  2. extracapsular cataract extraction (ECCE) - wide incision, good for rigid cataracts
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15
Q

Phacoemulsification procedure

A
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16
Q

Intraoperative complications of cataract surgery

A
  1. Posterior capsule rupture
  2. Floppy iris syndrome (when pt on tamsulosin)
  3. Choroidal haemorrhage!!
  4. Dropped nucleus (nucleus fragments escape the capsule)
17
Q

Post operative complications of cataract surgery

A

Early : corneal oedema, elevated IOP, endophthalmitis (1 week)

Late : PCO (most common), Irvine-Gass syndrome (cystoid macula oedema), retinal detachment, delayed endophthalmitis

18
Q

Endophthalmitis prevention

A

Providone iodine before operation

19
Q

Endophthalmitis features

A

vitritis (floaters and blurred vision), hypopyon, pain, corneal haze

20
Q

Endophthalmitis mx

A

Intravitreal abx
vitrectomy

21
Q

Endophthalmitis types

A

Acute - 1 week, staph epidermidis
Delayed - upto 6 weeks, propionibacterium acne
Post trauma - staph or bacillus cereus
fungal - candida

22
Q

Posterior capsule opacification

A

Most common delayed complication
Blurred vision, as if cataract has returned
Mx: Nd:YAG capsulotomy

23
Q

Secondary causes of congenital cataracts

A

Galactosaemia (AR)
Fabry disease (XLR)
Lowe syndrome (XLR)
Down syndrome
Congenital Rubella

24
Q

Lenticonus

A

Cone like protrusion of lens
Anterior lenticonus - Alport syndrome
Posterior lenticonus - Lowe syndrome

25
Q

Lentiglobus

A

Hemispherical protrusion of the lens

26
Q

Ectopia lentis

A

lens displacement

27
Q

What is the direction of displacement in these:

Familial ectopia lentis
Marfan’s syndrome
Homocystinuria
Weill-Marchesani syndrome

A

Familial - superotemporal (f)
Marfan - superotemporal (f)
Homocystinuria - inferonasal (y)
Weill Marchesani - anterior inferior

28
Q

Congenital aphakia

A

born without lens, FOX3 mutation

29
Q

U+D=V

A

U → vergence of light entering the lens (object rays)
D → vergence added to light by the lens (lens power)
V → vergence of light leaving the lens (image rays)

30
Q

Image by minus (biconcave) lens is …..

A

always virtual, erect and diminished

31
Q

Image by plus (biconvex) lens is

32
Q

Snellen chart

A

6 stays on top!

33
Q

LogMAR chart

A

0-1
0 normal vision
1 6/60 vision

each letter 0.02, subtrated from 1

34
Q

Duochrome test

A

Red - longer wavelength, image forms behind retina
Green - shorter wavelength, image forms in front of retina

35
Q

Retinoscopy

A

Objective measure of visual acuity
myopia - red reflex moves against direction of light
Hypermetropia - red reflex moves with the direction of light

Extra eye (7 decks)

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