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Opthalmology > Lens > Flashcards

Lens Flashcards

1
Q

Power of lens

A

16 to 17 dioptres

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2
Q

Refractive index of lens

A

1.39

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3
Q

Refractive index of nucleus of lens

A

1.4 to 1.41

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4
Q

Diameter of lens

A

9 to 10 mm

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5
Q

Different layers of the lens according to age

A 
From inner (oldest)
Embryonic
Foetal
Infantile
Adult
Cortex
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6
Q

Till what time period lens fibres are formed

A

Throughout life

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7
Q

Youngest fibres of the lens

A

Cortex

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8
Q

Thinnest part of lens

A

Capsule and posterior pole

4u

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9
Q

Primary metabolism of lens

Aerobic or anaerobic?

A

Anaerobic – 80% or more

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10
Q

Where does the lens derives its nutrition from

A

Aqueous humour

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11
Q

Which Germ layer is lens derived from

A

Surface ectoderm

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12
Q

Definition of cataract

A

Any opacity of lens which hinders the optical homogenicity

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13
Q

Genes involved in congenital cataract

A
  1. CRY-Crystalline
  2. cx-connexins
  3. MIP – Mayor Intrinsyc protein
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14
Q

TORCHS full form

A

Toxoplasma, others,rubella, CMV, herpes, syphilis

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15
Q

Most common cause in congenital cataract is

A

blue dot cataract

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16
Q

Most common cause for diminishing vision in congenital cataract is

A

Lamellar/zonular cataract

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17
Q

Cataracta pulverulenta

A

Powdery appearance of opacity

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18
Q

Which track track has onion peel appearance in congenital cataract

A

Posterior polar cataract

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19
Q

Which vitamin deficiency causes lamellar cataract

A

Vitamin D deficiency

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20
Q

Triad of congenital rubella syndrome

A

Cataract-Nuclear pearly cataract (most common)
Heart defects
Deafness

Mnemonic
CHD – congenital heart defect

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21
Q

Most common ocular feature of congenital rubella syndrome

A

Salt and pepper fundus

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22
Q

What is the pathology of salt-and-pepper fundus

A

Diffuse Choreoretinitis

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23
Q

Salt and pepper fundus differential diagnosis

A
  1. rubella
  2. syphilis
  3. retinitis pigmentosa
  4. myotonic dystrophy-Christmas tree cataract
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24
Q

5 Ps of myotonic dystrophy

A
  1. ptosis
  2. Presenile cataract
  3. IOP is low
  4. pigmentary retinopathy
  5. pupil miotic reacting slowly to light
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25
Q

Per-senile cataract causes

A

Myotonic dystrophy
Atopic dermatitis (Shield cataract)
Diabetes

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26
Q

Amaurosis

A

Total loss of vision

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27
Q

Amblyopia

A

Partial loss of vision

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28
Q

Amaurosis fugax

A

Transient loss of vision in curtain like manner

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29
Q

Time Of operating in congenital cataract

A

One month to 5/6 months

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30
Q

Treatment of choice in congenital cataract

A

Lens aspirations/lensectomy
Primary posterior capsulotomy
Anterior with direct to me
IOL implantation

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31
Q

Foveal reflex formed at what age

A

5–6 months

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32
Q

Why do we prescribe near glasses after a cataract surgery

A

Because accommodation is a lost after cataract surgery

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33
Q

Three ways of classification of acquired cataract

A

Aetiological
According to maturity
Anatomically

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34
Q

Which lenticular opacity causes maximum diminution of vision

A

Posterior Subcapsular

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35
Q

Why does posterior sub capsular cause maximum diminution of vision

A

As it is near the nodal point of eye

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36
Q

Two types of senile cataract

A

Cortical cataract and nuclear cataract

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37
Q

Stages of cortical cataract

A 
Lamellar separation
Incipient cataract/intumescent cataract 
Immaturecataract
Mature cataract
Hypermature cataract
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38
Q

Most common complication of cortical cataract

A

Phacolytic glaucoma

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39
Q

Aetiology of cortical cataract

A

Hydration

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40
Q

Aetiology of nuclear cataract

A

Nuclear sclerosis
.1 deposition of insoluble protein
2. deposition of pigments(Melanin and urochrome)

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41
Q

Clinical features of nuclear cataract

A

Immature cataract
Mature cataract
Hypermature nuclear sclerotic cataract

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42
Q

Most common complication of nuclear cataract

A

Subluxation of lens

Most common cause -trauma

43
Q

Second sight of old age

A

Improvement in near glasses

Nuclear cataract feature

44
Q

Why does second sight happen

A

Due to nuclear sclerosis there is increased refractive index of lens which increases the refractive power of the lens

45
Q

How can a person out of 40 or above have a emmetropic eyes

A

The person has had hypermetropia before 40 or

If myopia after 40

46
Q

Differential diagnosis for frequent change of glasses

A 
Early cataract (intumescent)
Late glaucoma (POAG)
Diabetes
47
Q

hyperglycaemia and hypoglycaemia have what shift

A

Hyperglycaemia has myopic shift (eg.-3 to -6)

Hypoglycaemia has hypermetropic shift (e.g.-3 to -1)

48
Q

Pathology behind myopic and Hypermetropic shift

A

In hyperglycaemia the lens swells up
Therefore the lens has more power
Therefore it causes myopia

49
Q

Differential diagnosis coloured halos

A

Cataract
Acute congestive glaucoma—> corneal edema
Mucopurulent conjunctivitis

50
Q

Fincham test

A

Passing stenopic slit in front of eye
If halos break - cataract
If halos don’t break- acute congestive glaucoma

51
Q

Metabolic cataract causes

A

Diabetes
Galactosemia
Chaliosis
Lowe’s syndrome/oculo cerebro-renal syndrome

52
Q

Features of metabolic cataract in diabetes

A

Sorbitol pathway
NADPH dependent aldose reductase
Snowstorm/ snowflake cataract
Most common in type one diabetes

53
Q

Reversible cataract

A

Galactosaemia metabolic cataract
By avoiding milk products

Kayser flesher ring (chaleosis)

54
Q

Features in the lens in Lowe’s syndrome

A
  1. metabolic cataract
  2. microphakia less than 9 mm
  3. posterior Lenticonus
55
Q

What type of lenticonus in Alports syndrome

A

ANTERIOR lenticonus
and posterior
(Can have both)

56
Q

What is complicated cataract

A

Cataract occurring as a complication to anterior segment or posterior segment disease

57
Q

Pathognomic feature of complicated cataract

A

Polychromatic lustre

58
Q

Breadcrumb appearance

A

Complicated cataract

59
Q

Most common type of complicated cataract

A

Posterior sub capsular

60
Q

Drugs causing toxic cataract

A
  1. steroids
  2. phenothiazine
  3. long acting miotics
  4. Amiodarone
  5. gold
  6. busulfan
  7. chloroquine
61
Q

Drugs causing anterior sub capsular cataract

A

Phenothiazine
Long acting miotics
Amiodarone
Gold

62
Q

Drugs causing posterior sub capsular cataract

A

Steroids
Busulfan
Chloroquine

63
Q

Most common complication of steroids in eye

A

Glaucoma

64
Q

Most common complication after topical steroids

A

Glaucoma

Open angle

65
Q

Most common complication of the systemic steroids

A

Cataract

Post subcapsular

66
Q

Radiational Cataract is seen in what occupation

A 
Glass worker(Infrared) 
Protected technicians, patients treated for malignant tumours, workers of atomic energy plants (Irradiation cataract)
Senile cataract (UV radiation cataract)
67
Q

Most common type of radiation cataract

A

Posterior sub capsular

68
Q

Most common type of radiation cataract
Most common cause of complicated cataract
Cataract caused due to steroids-most common
Maximum diminution of vision in which cataract

A

Posterior sub capsular

69
Q

Most radio sensitive part of the eye

A

Lens

70
Q

Most radio resistant part of the eye

A

Sclera

71
Q

Most radio sensitive part of the retina

A

Photo receptors (rods and cones)

72
Q

Most radio resistant part of retina

A

Ganglion cell layer

73
Q

Traumatic cataract features

A

Rossette shape cataract
Vossius ring
Berlin’s edema/commotio retinae

(If you don’t know what these are pls check notes)

74
Q

What forcep is used for extraction of the capsule in intra capsular cataract extraction

A

Arugas forceps

75
Q

Only indication of ICCE

A

Subluxation of lens

76
Q

What is the contract indication of ICCE

A

It is contraindicated in children
This is because the Weigerts ligament attaches the capsule and the anterior hyaloid membrane which may pull the vitreous during ICCE which is a big risk of retinal detachment

77
Q

Two parts of an IOL

A

Optics and haptics

78
Q

What are IOLs made up of

A

PMMA

Polymethyl methacrylate

79
Q

Foldable IOLs material

A

Acrylic (most common)
Silicon
Hydrogel

80
Q

Incision size in phacoemulsification

A

2.75-3.2 mm

81
Q

What dye is used to stain the capsule

A

Triptan blue dye

82
Q

Wavelength of femtolaser

A

1054 nm

83
Q

Pulse duration of femtolaser

A

10 to the power of -15 seconds

84
Q

Different sites for IOL

A
  1. anterior chamber
  2. Iris claw lens
  3. scleral fixated
85
Q

What is biometry

A

Method of calculating the power of IOL

86
Q

What is used to measure the axial length

A

A scan

87
Q

What does keratometry measure

A

Measuring curvature

88
Q

SRK formula

A

P = A -2.5 -0.9 K

A is a constant

89
Q

If Cornea diameter is more than 26 mm which formula do you use to calculate the power

A

SRK/t

90
Q

Other formula is used to calculate the power of IOL

A

Holladay Formula

91
Q

Morphological types of after cataract

A

Diffuse
Elschnig’s pearls
Soemmering’s rings

92
Q

Treatment of each type of after cataract

A

Dense membranous- surgical membranectomy
Elshnig’s-YAG laser + posterior capsulotomy
Soemmerings ring-no treatment

93
Q

Ocular features of marfans syndrome

A
  1. axial myopia
  2. Megalocornea >13mm (Most prominent)
  3. supra temporal ectopia lentis
  4. lattice degeneration
  5. retinal detachment
94
Q

Shield cataract is seen in which condition and what site opacity is present

A

Atopic dermatitis

ASC opacity

95
Q

Ectopia lentis in Marfans syndrome

A

Superior temporal

96
Q

Ectopia lentis in homocystinuria

A

Inferonasal

97
Q

Ectopic lentis in weil marchesani

A

Inferonasal

Micro spherophakia

98
Q

features of Ehler Danlos

A

Blue sclera

Downward and forward ectopic lentis

99
Q

Subluxation of lens main features

A

Simple ectopia lentis
Ectopia lentis et pupillae
Ectopia lentis associated with syndrome

(Also know what they mean -.-)

100
Q

Endophthalmitis early onset cause

A

Staphylococcus epidermidis

101
Q

Endophthalmitis late onset causes

A

Propionibacterium acne

Fungal- MC candida

102
Q

MCC subluxation of lens

A

Trauma

103
Q

Most dreaded complications of cataract surgery

A

Endophthalmitis

104
Q

MC long term/late complications after cataract surgery

A

After cataract

Opthalmology (10 decks)

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