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Opthalmology > Lens > Flashcards

Lens Flashcards

(104 cards)

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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
Per-senile cataract causes
Myotonic dystrophy Atopic dermatitis (Shield cataract) Diabetes
26
Amaurosis
Total loss of vision
27
Amblyopia
Partial loss of vision
28
Amaurosis fugax
Transient loss of vision in curtain like manner
29
Time Of operating in congenital cataract
One month to 5/6 months
30
Treatment of choice in congenital cataract
Lens aspirations/lensectomy Primary posterior capsulotomy Anterior with direct to me IOL implantation
31
Foveal reflex formed at what age
5–6 months
32
Why do we prescribe near glasses after a cataract surgery
Because accommodation is a lost after cataract surgery
33
Three ways of classification of acquired cataract
Aetiological According to maturity Anatomically
34
Which lenticular opacity causes maximum diminution of vision
Posterior Subcapsular
35
Why does posterior sub capsular cause maximum diminution of vision
As it is near the nodal point of eye
36
Two types of senile cataract
Cortical cataract and nuclear cataract
37
Stages of cortical cataract
``` Lamellar separation Incipient cataract/intumescent cataract Immaturecataract Mature cataract Hypermature cataract ```
38
Most common complication of cortical cataract
Phacolytic glaucoma
39
Aetiology of cortical cataract
Hydration
40
Aetiology of nuclear cataract
Nuclear sclerosis .1 deposition of insoluble protein 2. deposition of pigments(Melanin and urochrome)
41
Clinical features of nuclear cataract
Immature cataract Mature cataract Hypermature nuclear sclerotic cataract
42
Most common complication of nuclear cataract
Subluxation of lens | Most common cause -trauma
43
Second sight of old age
Improvement in near glasses | Nuclear cataract feature
44
Why does second sight happen
Due to nuclear sclerosis there is increased refractive index of lens which increases the refractive power of the lens
45
How can a person out of 40 or above have a emmetropic eyes
The person has had hypermetropia before 40 or | If myopia after 40
46
Differential diagnosis for frequent change of glasses
``` Early cataract (intumescent) Late glaucoma (POAG) Diabetes ```
47
hyperglycaemia and hypoglycaemia have what shift
Hyperglycaemia has myopic shift (eg.-3 to -6) | Hypoglycaemia has hypermetropic shift (e.g.-3 to -1)
48
Pathology behind myopic and Hypermetropic shift
In hyperglycaemia the lens swells up Therefore the lens has more power Therefore it causes myopia
49
Differential diagnosis coloured halos
Cataract Acute congestive glaucoma—> corneal edema Mucopurulent conjunctivitis
50
Fincham test
Passing stenopic slit in front of eye If halos break - cataract If halos don’t break- acute congestive glaucoma
51
Metabolic cataract causes
Diabetes Galactosemia Chaliosis Lowe’s syndrome/oculo cerebro-renal syndrome
52
Features of metabolic cataract in diabetes
Sorbitol pathway NADPH dependent aldose reductase Snowstorm/ snowflake cataract Most common in type one diabetes
53
Reversible cataract
Galactosaemia metabolic cataract By avoiding milk products Kayser flesher ring (chaleosis)
54
Features in the lens in Lowe’s syndrome
1. metabolic cataract 2. microphakia less than 9 mm 3. posterior Lenticonus
55
What type of lenticonus in Alports syndrome
ANTERIOR lenticonus and posterior (Can have both)
56
What is complicated cataract
Cataract occurring as a complication to anterior segment or posterior segment disease
57
Pathognomic feature of complicated cataract
Polychromatic lustre
58
Breadcrumb appearance
Complicated cataract
59
Most common type of complicated cataract
Posterior sub capsular
60
Drugs causing toxic cataract
1. steroids 2. phenothiazine 3. long acting miotics 4. Amiodarone 5. gold 6. busulfan 7. chloroquine
61
Drugs causing anterior sub capsular cataract
Phenothiazine Long acting miotics Amiodarone Gold
62
Drugs causing posterior sub capsular cataract
Steroids Busulfan Chloroquine
63
Most common complication of steroids in eye
Glaucoma
64
Most common complication after topical steroids
Glaucoma | Open angle
65
Most common complication of the systemic steroids
Cataract | Post subcapsular
66
Radiational Cataract is seen in what occupation
``` Glass worker(Infrared) Protected technicians, patients treated for malignant tumours, workers of atomic energy plants (Irradiation cataract) Senile cataract (UV radiation cataract) ```
67
Most common type of radiation cataract
Posterior sub capsular
68
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
Posterior sub capsular
69
Most radio sensitive part of the eye
Lens
70
Most radio resistant part of the eye
Sclera
71
Most radio sensitive part of the retina
Photo receptors (rods and cones)
72
Most radio resistant part of retina
Ganglion cell layer
73
Traumatic cataract features
Rossette shape cataract Vossius ring Berlin’s edema/commotio retinae (If you don’t know what these are pls check notes)
74
What forcep is used for extraction of the capsule in intra capsular cataract extraction
Arugas forceps
75
Only indication of ICCE
Subluxation of lens
76
What is the contract indication of ICCE
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
Two parts of an IOL
Optics and haptics
78
What are IOLs made up of
PMMA | Polymethyl methacrylate
79
Foldable IOLs material
Acrylic (most common) Silicon Hydrogel
80
Incision size in phacoemulsification
2.75-3.2 mm
81
What dye is used to stain the capsule
Triptan blue dye
82
Wavelength of femtolaser
1054 nm
83
Pulse duration of femtolaser
10 to the power of -15 seconds
84
Different sites for IOL
1. anterior chamber 2. Iris claw lens 3. scleral fixated
85
What is biometry
Method of calculating the power of IOL
86
What is used to measure the axial length
A scan
87
What does keratometry measure
Measuring curvature
88
SRK formula
P = A -2.5 -0.9 K | A is a constant
89
If Cornea diameter is more than 26 mm which formula do you use to calculate the power
SRK/t
90
Other formula is used to calculate the power of IOL
Holladay Formula
91
Morphological types of after cataract
Diffuse Elschnig’s pearls Soemmering’s rings
92
Treatment of each type of after cataract
Dense membranous- surgical membranectomy Elshnig’s-YAG laser + posterior capsulotomy Soemmerings ring-no treatment
93
Ocular features of marfans syndrome
1. axial myopia 2. Megalocornea >13mm (Most prominent) 3. supra temporal ectopia lentis 4. lattice degeneration 5. retinal detachment
94
Shield cataract is seen in which condition and what site opacity is present
Atopic dermatitis | ASC opacity
95
Ectopia lentis in Marfans syndrome
Superior temporal
96
Ectopia lentis in homocystinuria
Inferonasal
97
Ectopic lentis in weil marchesani
Inferonasal | Micro spherophakia
98
features of Ehler Danlos
Blue sclera | Downward and forward ectopic lentis
99
Subluxation of lens main features
Simple ectopia lentis Ectopia lentis et pupillae Ectopia lentis associated with syndrome (Also know what they mean -.-)
100
Endophthalmitis early onset cause
Staphylococcus epidermidis
101
Endophthalmitis late onset causes
Propionibacterium acne | Fungal- MC candida
102
MCC subluxation of lens
Trauma
103
Most dreaded complications of cataract surgery
Endophthalmitis
104
MC long term/late complications after cataract surgery
After cataract

Opthalmology (10 decks)

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