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C.EyeMD > CC.ataract > Flashcards

CC.ataract Flashcards

1
Q

Leading cause of visual impairment and blindness throughout the world:

A

Cataract

Projected to reach 40M in 2020

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2
Q

Increased susceptibility to cataract formation

A 
Increasing age
AfAm
Women
Smokers (nuclear) 
Low education status
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3
Q

Primary goal in evaluation of Cataract patients

A

To determine if cataract is main cause of poor vision

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4
Q

Cortical cataract

Effect on near:
Effect on distance:
Glare:
Induced myopia:

A

Cortical cataract

Effect on near: Mild
Effect on distance: Mild
Glare: Mild
Induced myopia: None

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5
Q

Nuclear cataract

Effect on near:
Effect on distance:
Glare:
Induced myopia:

A

Nuclear cataract

Effect on near: None
Effect on distance: Moderate
Glare: Mild
Induced myopia: Moderate

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6
Q

Posterior subcapsular cataract

Effect on near:
Effect on distance:
Glare:
Induced myopia:

A

Posterior subcapsular cataract

Effect on near: Marked
Effect on distance: Mild
Glare: Marked
Induced myopia: None

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7
Q

Clinical presentation of Cataract patients

A 
Decreased VA and function 
Glare
Myopic shift
Altered contrast sensitivity
Monocular diplopia
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8
Q

Type of Cataract that will benefit from pupillary dilation as non-surgical management

A

Axial cataract

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9
Q

Indications for cataract surgery

A 
Patient desire
Loss of stereopsis
Diminished peripheral vision
Disabling glare
Symptomatic anisometropia
Dense cataract that obscures fundus
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10
Q

Medical indications for cataract surgery

A

Phacolytic glau
Phacomorphic glau
Phaco antigenic uveitis
Lens dislocation

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11
Q

How do you check for lenticular contribution?

A

Thin slit beam focused on posterior capsule
Change light to cobalt blue
If posterior capsule is no longer illuminated, contribution to visual acuity is significant (20/50 or worse)

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12
Q

Special test for oil droplet cataracts

A

DO through +10D at 2ft

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13
Q

Special tests for potential acuity estimation

A

Laser interferometry

Potential acuity meter

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14
Q

Special tests for macula function

A 
Maddox Rod
Photostress recovery time
Blue light entoptoscopy
Purkinje's entoptic phenomenon
ERG/VER
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15
Q

Preoperative cataract tests

A 
Refraction
Biometry
Corneal topo
Corneal pachy
Spec mic
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16
Q

Types of biometry

A

Applanation

Immersion

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17
Q

What is the normal axial length of the eye?

A

Ave 23.5 mm

Range 22-24.5 mm

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18
Q

What is the normal anterior chamber depth of the eye?

A

Ave 3.24 mm

Range 2.5-4 mm

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19
Q

What is the normal lens thickness of the eye?

A

Ave 4.63

May reach up to 7 mm

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20
Q

5 spikes in biometry

A 
Cornea
Ant capsule
Post capsule
Retina
Sclera
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21
Q

Good A scan

A

No spikes in front of retina
Spikes are steeply rising
Reproducible

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22
Q

When to repeat A-scan measurements?

A

Axial length less than 21 or more than 25 in either eye
Diff between 2 eyes of more than 0.3 mm
Axial length does not correlate with refraction
Poor spikes
Wide variations in AL

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23
Q

When to repeat Keratometry?

A

Corneal power less than 40D or more than 47D

Ave K diff more than 1D

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24
Q

What does an IOL master/Optical coherence biometry do?

A

Measures AL as an optical path length bet cornea and retina

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25
Q

Advantages of IOL master/ Optical coherence biometry

A

Non contact
Accurate
Useful even for extreme axial lengths, a/pseudophakic, silicone filled eyes

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26
Q

Disadvantages of optical coherence biometry

A

Cannot penetrate dense cataracts or PSC

Expensive

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27
Q

What is the SRK formula?

A

SANDERS, RETZLAFF, KRAFF

P= A constant - 2.5AL - 0.9Kave

Linear regression
Best for 22.5 to 25mm

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28
Q

Limitations of SRK formuka

A

Assumes linear relationship

Inaccurate for very short or very long

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29
Q 
IOL calculation formulas
Very long eyes more than 26mm:
Medium long eyes 24.5-26mm:
Short eyes less than 22mm:
Very short eyes less than 19mm:
Normal eyes 22-26mm:
A 
IOL calculation formulas
Very long eyes more than 26mm: SRK-T
Medium long eyes 24.5-26mm: Holladay I
Short eyes less than 22mm: Hoffer Q
Very short eyes less than 19mm: Holladay II
Normal eyes 22-26mm: SRK II

Haigis - Accurate for any length but needs to be optimised in extremely long or short eyes

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30
Q

Power adjustment if putting IOL in sulcus

A

Decrease by 0.7 to 1D

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31
Q

Power adjustment if fixating IOL to sclera

A

Increase by 0.5 D

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32
Q

Power adjustment if placing ACIOL

A

Decrease by 3D

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33
Q

Cataract surgery done in 800 BC

A

Couching

Sharp needle to corneoscleral junction
Blunt needle to wiggle lens free from zonules
Lens displaced into vit

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34
Q

Origin of word couching

A

Coucher/kushe - put to bed

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35
Q

Person who developed early ECCE technique wherein incision is done on inferior cornea and lens capsule is incised; nucleus is expressed and cortex is removed by currettage

A

Daviel

Procedure complicated by retained lens and endophth

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36
Q

Contribution of Von Graefe in cataract surgery

A

Developed knife that created better apposed incision
Decreased infection rates and uveal prolapse
Still with retained lens

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37
Q

Technique of Sharp in early ICCE

A

Lens and capsule extracted via limbal incision using thumb

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38
Q

Smith-Indian operation in ICCE

A

Extraction of lens using muscle hook

imagine Indian with a hook

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39
Q

Contribution of Verhoeff/Kalt in early ICCE

A

Toothless forceps

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40
Q

Erysiphakes in early ICCE

A

Suction cup-like device

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41
Q

Krwawicz in early ICCE

A

Cryoprobe

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42
Q

Advantages of ICCE

A

Entire lens removed
Less sophisticated instruments
Useful for luxated cataracts

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43
Q

Disadvantages of ICCE

A 
Delayed healing and rehab
Astigmatism
Vit/iris incarceration
CME/RD more common
Limited IOL choice and position
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44
Q

Advantages of ECCE vs ICCE

A 
Less endothelial trauma
Less astigmatism
More secure wound
Less vit loss
Better IOL placement
Reduced CME, RD, corneal edema
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45
Q

Disadvantages of ECCE vs ICCE

A

Can’t be used for cataracts with weak zonules

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46
Q

Person who developed Phaco in 1967

A

Charles Kelman

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47
Q 
Type of gel with the ff characteristics:
Adheres to self
High MW
High sutface tension
Easily aspirated
Maintains AC during capsulorrhexis

Example of this gel?

A

Cohesive

Healon

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48
Q 
Type of gel with the ff characteristics:
Little tendency for self adherence
Low MW
Low surface tension
Not easily aspirated
Tamponades vit in PC rent

Example?

A

Dispersive

Viscoat

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49
Q

Parts of phaco tip

A 
Aspiration port
Stroke length
Irrigation post
Silicone irrigation sleeve
Irrigation sleeve hub
Handpiece vody
Aspiration line
Ultrasound power line
Irrigation line
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50
Q

Formation of vacuoles in liquid by swiftly moving solid body. Collapse of vacuole - released energy and crushed lens material.

A

Cavitation

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51
Q

To cut unevenly with rapidly intermittent vibration

A

Chatter

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52
Q

Sudden action producing impact

A

Stroke

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53
Q

Strokes per second

A

Frequency

27000 to 60000 Hz

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54
Q

Occurs when tip encounters nuclear material

A

Load

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55
Q

Transducer which transforms electrical to mechanical energy

A

Piezoelectric

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56
Q

Ability of phaco needle to vibrate and cavitate adjacent lens material

A

Power

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57
Q

Used to match optimum driving frequency of ultrasonic board with frequency of phaco handpiece

A

Tuning

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58
Q

Frequencies above human audibility

A

Ultrasonic

More than 20k vibrations per second

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59
Q

Rate at which fluid flows from eye; attractive force of Handpiece

A

Aspiration flow rate

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60
Q

Ability of fluidic system to attract lens material

A

Followability

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61
Q

Obstruction of aspiration porr

A

Occlusion

This is necessary to create vacuum

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62
Q

Rate at which vacuum builds once aspiration port is occluded. Directly related to aspiration flow rate.

A

Rise time

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63
Q

Occurs after occlusion when high vacuum is broken. Fluid from AC enters phaco tip. AC may become shallow.

A

Surge

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64
Q

Suction force exerted on fluid in aspiration line of eye. The holding force for the material occluding the phaco tip.

A

Vacuum

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65
Q

Process by which vacuum is equalised to atmospheric levels to minimize surge

A

Venting

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66
Q

Maintains AC depth and cools phaco probe

A

Irrigation

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67
Q

Withdrawal of fluid and lens material from eye

A

Aspiration

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68
Q

Examples of peristaltic pump

A 
LUIS
Legacy
U2
Infiniti
Sovereign
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69
Q

Consists of rollers moving along solid tubing
Relative vacuum at aspiration port
Vacuum response relatively rapid
Linear control by increasing speed of roller

A

Peristaltic pump

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70
Q

Flow of gas or fluid across port creates vacuum
Vacuum proportional to rate of flow
Linear and rapid rize
Allows instantaneous venting

A

Venturi pump

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71
Q

Examples of venturi pump

A

Millenium

Visalis

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72
Q

Flexible diaphragm overlying fluid chamber with 1 way valves at inlet and outlet
Creates relative vacuum that shuts exit valve when diaphragm moves out
Increases AC pressure and opens exit valve when diaphragm moves in
Slow rise in vacuum but when port is occluded, vacuum rises exponentially

A

Diaphragm pump

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73
Q

Example of diaphragm pump

A

Oertli

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74
Q

Cataract surgery complications

A 
Corneal edema
CME
High IOP
PC rent
Vit loss
Astigmatism
Retained lens
Endophthalmitis
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75
Q

Causes of corneal edema in cataract surgery

A

Mechanical trauma
Prolonged phaco time
Inflammation
IOP elevation

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76
Q

Characteristics of CME post cataract surgery

A

Aka Irvine Gass syndrome
More common in ICLE
Peak at 6 to 10 weeks postop
Manage using topical NSAID

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77
Q

Signs of capsular rent

A

Sudden deepening of AC
Momentary pupil dilation
Decreased mobility of nuclear pieces
Vit aspiration

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78
Q

Management of PC rent

A

Inject gel before removing phaco tip
Lower bottle height
Lower settings
AV

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79
Q

Causes of high IOP post cataract surgery

A

Retained gel

Look for other causes if persistent

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80
Q

Management of astigmatism post ECCE

A

ROS 6 to 8 weeks post op

Up to 2D WTR will resolve

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81
Q

Complication of too early or too many ROS in ECCE

A

Too much flattening

Wound leak

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82
Q

Time delineation between acute and chronic endophthalmitis

A

6 weeks

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83
Q

Pathogens for acute endophthalmitis

A

S. epidermidis
S. aureous
Streptococcus sp
Gram negative bacteria

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84
Q

Pathogens for chronic endophthalmitis

A

P. acnes
Coagulase neg Staph
Fungi

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85
Q

MC differential of Endophthalmitis

A

TASS

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86
Q

Characteristics of TASS

A

Limbus to Limbus edema
Diagnosis of exclusion
Onset within 24 hours

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87
Q

Findings of EVS/Endophthalmitis vitrectomy study

A

PPV beneficial for VA of LP or worse

IV antibiotics not beneficial

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88
Q

2 groups in EVS

A 
VIT = underwent PPV
TAP = underwent vitreous tap and biosy

Both groups received intravit vanco plus amik and subconj vanco plus dexa

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89
Q

How long before normal coagulation is restored for patients taking warfarin?

A

3 to 5 days

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90
Q

How long before platelet function is restored in patients taking antiplatelets?

A

10 to 21 days

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91
Q

Conditions to treat before cataract surgery

A

Blepharitis

Dry eye

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92
Q

Special considerations for post keratoplasty patients

A

Corneal graft may not survive
Scleral tunnnel
Advise patients re reduced clarity
Coat with gel

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93
Q

Special considerations for post LASIK patients

A

Less predictable outcomes

Postoperative hyperopia is common

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94
Q

What to do or prepare for patients with small pupil

A

Kuglen or Lester hooks
Pupil expansion devices
Viscodissection with high viscosity OVD

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95
Q

Precautions for advanced cataract

A

Decrease surgical manipulation
Create larger capsulorrhexis
Thorough hydrodissection and delineation
May employ viscodissection to separate sticky cortical attachments

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96
Q

Precautions for intumescent cataracts

A 
Weak zonules
Fragile capsules
Use trypan blue
Use cystotome with gel
Segmentation may be hard
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97
Q

Characteristics of the lens

A

Transparent

Biconvex

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98
Q

True or false -

The lens retains its innervation and blood supply after fetal development

A

False

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99
Q

Other name for lens zonules

A

Zonules of Zinn

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100
Q

Imaginary line connecting anterior and posterior poles

A

Optic axis

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101
Q

Surface lines passing from one pole to another

A

Meridian

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102
Q

The greatest circumference of the lens is found at the ___.

A

Equator

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103
Q

Normal index of refraction of the lens

A
  1. 4 centrally

1. 36 peripherally

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104
Q

Contribution of lens to refractive power of eye

A

1/3

15 to 20D

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105
Q

The lens epithelium is found (anteriorly vs posteriorly)

A

Anteriorly

Single layer beneath anterior capsule

106
Q

AP diameter of lens at birth vs. adulthood

A

3.5 mm vs 5.0 mm

107
Q

Transverse diameter of lens at birth vs adulthood

A

6.4 mm vs 9 mm

108
Q

Weight of lens at birth vs at adulthood

A

90 mg vs 255 mg

109
Q

Characteristics of lens capsule

A

Elastic and transparent
Molds lens during accomodation
Thickest anterior and posterior preequatoria
Thinnest at central posterior pole (2 to 4 um)
Increases thickness throughout life

110
Q

Attachment of zonules to the capsule

A

Zonular lamella

111
Q

Type of collagen in lens capsule

A

Type IV

112
Q

Origin of zonular fibers

A

Pars plana and plicata

113
Q

Insertion of zonular fibers

A

Equator

  1. 5 mm anteriorly
  2. 25 mm postetiorly
114
Q

Composition of zonular fibers

A

Fibrillin

Eosiniohilic structures with positive PAS reaction

115
Q

Characteristics of lens epithelium

A

Metabolically active, synthesises ATP
Mitotic (germinative zone)
Cells migrate towards equator to the lens fibers

116
Q

True or false

Lens cell are lost as a patient grows old

A

False

There is just crowding; cells are compact within the lens

117
Q

Location of old and new lens fibers

A 
Old centrally
New outermost (cortex)
118
Q

What are lens sutures?

A

Areas where cells converge

119
Q

True or false

There is no morphological distinction between the cortex and the nucleus

A

True

120
Q

Composition of lens

A

66% water
33% CHON

Cortex more hydrated than nucleus

121
Q

Electrolyte concentration in lens vs aqueous

A 
Lens
Na 20mM
K 120mM
Amino acids higher
Chloride lower

Aqueous
Na 150mM
K 5mM

122
Q

How do older lens cells communicate?

A

Low resistance gap junctions

MIP Aquaporin 0 water channels

123
Q

Active pumps on the lens

A

Na K ATPase
Ca ATPase
Amino acid pump

124
Q

Molecule that diffuses through lens through facilitated diffusion

A

Glucose

125
Q

Electrolytes and molecules that exhibit passive diffusion in lens

A

Na - higher concentration posteriorly
K - higher concentration antetiorly
Water

126
Q

Active pumps are mainly seen where on the lens

A

Anterior epithelium

127
Q

What theory regulates water and cation balance in the lens?

A

Pump leak theory

Membrane potential inside is - 70mV
Between anterior and posterior lens - 23mV

128
Q

Mechanism by which eye changes focys

A

Accomodation

129
Q

Name the theory which states that accommodative change occurs in the anterior lens capsule where a central anterior buldge occurs:

A

Von Helmholtz

Von has a bulge anteriorly

130
Q

What type of nerve fibers mediate accomodation?

A

Parasympathetic nerve fibers of CN III

131
Q

What happens when the ciliary muscles/sphincter contracts?

A

Muscle ring diameter increased
Zonular tension relaxed
More spherical lens

132
Q

Normal amplitude of accomodation for
Adolescents:
Adults at 40 yo:
After 50:

A

Normal amplitude of accomodation for
Adolescents: 12 to 16D
Adults at 40 yo: 4 to 8D
After 50: less than 2D

4 at 40
50 need doblevista

133
Q

Crystallins constitute __% of total lens proteins

A

80

134
Q

1/3 of lens proteins by mass
Largest at 600kDa
Prevents denaturation and insolubilization of other proteins

A

Alpha

135
Q

Constitutes 50 percent of mass of proteins in lens

A

Beta

136
Q

Lens proteins can be differentiated by solubility in __ and __.

A

Water and urea

137
Q

Cytoskeletal proteins that provide structural framework

A

Urea soluble

Structural and Soluble

138
Q

Urea insoluble proteins are seen in:

A

Plasma membranes of lens fibers (water channels and adhesion molecules)
Increases with age

139
Q

Urea soluble proteins are composed of ___ filaments

A

Intermediate

Types
Vimentin
Beaded, made from phakinin and filensin, disruption of which causes cataracts

140
Q

Aquaporin 0 is a (urea insoluble vs soluble protein)

A

Insoluble

141
Q

Changes of lenses with aging

A

Increased insolubility
Increased disulfide and nondisulfide bonds
Decreased reduced glutathione
Increased protein aggregation

142
Q

Lens transparency is largely dependent on __ metabolism.

A

Glucose

143
Q

Mechanisms by which glucose enters lens

A

Simple diffusion
Facilitated diffusion

G6P is the major transported form

144
Q

2 pathways for glucose metabolism in lens

A

Anaerobic glycolysis - more active

HMP shunt

145
Q

Number of ATP produced in aerobic glycolysis

A

36

146
Q

Number of ATP produced in anaerobic glycolysis

A

2

147
Q

Krebs cycle/TCA pathway produces __% of lens ATP

A

25

148
Q

HMP produces _% of lens ATP

A

5

It’s more. Important for NADPH production.

149
Q

Which pathway is activated in patients with sugar cataracts?

A

Sorbitol pathway

150
Q

What do free radicals do in the lens?

A

Damages lens fibers

Lipid peroxidation, leading to opacification

151
Q

What are the enzymes that protect against free radical damage?

A

Catalase - breaks down peroxide, catalysed by glutathione petoxifase

Superoxide dismutase - catalyses destruction of superoxide anion O2-, producing H2O2

Glutathione peroxidase

152
Q

Effect of oxidative damage to lens

A

Myopic shift
Increased opacification
Nuclear cataract formation

153
Q

When does lens formation start?

A

25th day AOG
Optic vesicles form from forebrain or diencephalon

Gift of sight at Christmas

154
Q

When do the following structures form?
Lens placode:
Lens pit:
Lens vesicle:

A

When do the following structures form?
Lens placode: 27th day AOG
Lens pit: 29th day
Lens vesicle: 30th day

155
Q

Characteristic of lens vesicle

A

Single layer of cuboidal cells encased in BM which is the lens capsule

156
Q

When do the cells in the posterior layer stop dividing and start elongating?

A

40th day AOG
Become lens fibers
Make up nucleus

Think 40th day of death

157
Q

When do secondary lens fibers form?

A

2 to 8 months of gestatiom

Cells near equator elongate

158
Q

Rate of increase of mass of lens

A

2 mg per year

159
Q

Remnant of the hyaloid artery

A

Mittendorf dot

Hyaloid artery disappears at 9 weeks AOG

160
Q

Origin of Zonules of Zinn

A

Ciliary epithelium at 3 months

161
Q

When is the Y suture recognizable

A

At more than 2 months of gestation

162
Q

In congenital aphakia, what is the difference between primary and secondary aphakia?

A

Primary - lens placode fails to form

Secondary - absorption of lens, more common

163
Q

Primary versus secondary lens coloboma

A

Primary - wedge shaped defect

Secondary - flattening or indentation due to lack of ciliary body

164
Q

Remnant of TVL

A

Epicapsular star

Tiny brown or golden flecks on anterior capsule

165
Q

Genes involved in Peters anomaly

A

PAX6
PITX2
FOXC1

166
Q

Features of Peters anomaly

A

Adhesion between lens and cornea
Anterior cortical or polar cataract
Misshapen lens displaced anteriorly into the pupillary space and anterior chamber
Microspherophakia

167
Q

Characteristics of microspherophakia

A

Lens small in diameter and spherical
Highly myopic eye
Association with other syndromes
At risk for pupillary block

168
Q

What is aniridia?

A

Partial or complete absence of iris

169
Q

Gene associated with aniridia?

A

PAX6

2/3 familial
1/3 sporadic

170
Q

Changes in lens as one grows old

A 
Inc weight and thickness
Decrease accomodation
Nuclear sclerosis
Modification of proteins
Dec glutathione and potassium
Inc sodium and calcium
171
Q

Characteristics of nuclear cataracts

A

Slow progression
Usually bilateral
Greater distance impairment
Myopic shift

172
Q

Characteristics of cortical cataracts

A 
Local disruption of fiber cells
Bilateral and asymmetric
Glare and monocular diplopia
Rapid or slow progression
Vacuoles or clefts on slit lamp
Wedge shaped cortical spokes
173
Q

What is an intumescent cataract?

A

Cataract with increased water in lens

Associated with shallow AC

174
Q

Lens changes in a hypermature cataract

A

Degenerated cortical materisl leaks

Capsule becomes wrinkled and shrunken

175
Q

What is a morgagnian cataract?

A

A cataract with a liquefied cortex and freely moving nucleus

176
Q

Slit lamp findings in PSC

A

Subtle iridescent sheen

Granular plaque like opacities later on

177
Q

Associations of PSC

A

Trauma
Steroid use
Alcoholism
Radiation

STAR

178
Q

Cataract in Steroid users

A

PSC
Dose and duration dependent
Oral, topical, IV or inhalational

179
Q

Lens changes seen in phenothiazine (chlorpromazine, thioridazine) users

A

Pigment deposits in anterior lens
Dose and duration dependent

This is a psychotropic medication

180
Q

Lens changes in patients using miotics

A

Small vacuoles within and posterior to anterior capsule

PSC or nuclew4

Pilocarpine
Echothiopate iodide

181
Q

Eye changes in amiodarone users

A

Stellate anterior axial pigment deposition

Deposits in corneal epithelium/verticillata

182
Q

Cataract association of tamoxifen

A

None

But associated with crystalline maculopathy

183
Q

What is a Vossius ring?

A

Pigment from pupillary ruff is imprinted anteriorly

184
Q

Cataract associated with trauma

A

Stellate or rosette shaped cataract

May also dislocate or subluxate

185
Q

Causes of metabolic cataracts

A 
DM
Galactosemia
Wilsons disease
Hypocalcemia
Myoyinic dystrophy
186
Q

Characteristics of cataracts in patients with galactosemia

A

Usually bilateral
First few weeks of life
Secondary to excess galactose

187
Q

Enzymes associated with galactosemia

A

Classic Gal1PUT
Galactokunase
UDP galactose 4 epimerase

188
Q

Eye findings in Wilsons disease

A

Kayser-Fleischer rings in DM
Sunflower cataract
Reddish brown pigments due to cuprous oxide

Decrease in VA not severe

189
Q

Lens changes in hypocalcemia

A

Metabolic cataract

Punctate iridescent opacities in anterior or posterior cortex

190
Q

Features of Myotonic dystrophy

A 
Autosomal dominant
Delayed relaxation of muscles
Ptosis
Weak facial muscles
Cardiac conduction defects
Prominent frontal balding
Polycgromatic iridescent cataracts consisting of whorls of plasmalemma
191
Q

Procedures that cause cataracts

A 
PPV
Intravit injections
Trab
PK
DSEK
192
Q

Uveitic cataract features

A

Due to chronic uveitis or chronic steroids
Usually with PSC
Posterior synechia
Calcium deposits

193
Q

Features of patients with galactosemia

A

Malnutrition
Jaundice
Intellectual disability

Oil droplet cataract

194
Q

Management of galactosemia

A

Elimination of galactose or milk in diet

195
Q

Management of galactosemia

A

Elimination of galactose or milk in diet

196
Q

Examples of Venturi Pump

A

Millenium

Accurus

197
Q

True or false

The lens is not sensitive to radiation

A

False

Extremely sensitive
Younger more susceptible
May present after 20 years
Punctate opacities in PC, Feathery ASC

198
Q

What is a glassblower’s cataract?

A

Outer layers of AC may peel off as single layer due to IR damage

199
Q

Characteristics of UV Induced cataract

A

Seen more in men

10% total risk of cortical cataract

200
Q

Where is Fe deposited in siderosis bulbi?

A

TM
Lens epithelium
Iris
Retina

201
Q

What is Chalcosis?

A

Occurs with copper IOFB.

Results to sunflower cataract and KF ring

202
Q

Cataract in electrical injury

A

Anterior midperiphery - linear opacities in anterior subcapsular area

(Vacuoles first then linear opacities)

203
Q

Worse damage to eye - alkali vs acid

A

Alkali

204
Q

Snowflake cataracts are seen in what disease?

A

DM
Bilateral widespread subcapsular lens changes of abrupt onset
Usually in young with uncontrolled DM
Gray white subcapsular opacities initially in superficial anterior and posterior lens cortex
Vacuoles and clefts in underlying cortex
Increase in sorbitol, CHON glycation, oxidative stress

205
Q

Types of age related cataracts

A

Nuclear
Cortical
PSC

206
Q

What is a congenital cataract?

A

Cataract present at birth or develops within 1 year

207
Q

Incidence of congenital cataracts

A

1 in 2000
One third as part of syndrome
One third isolated inherited
One third undetermined

208
Q

Most common congenital cataract

A 
Lamellar aka zonular
AD
Due to transient toxic influence
Smaller and deeper if earlier
Opacified layer in between clear center and clear cortex
Disc shaped configuration
Horseshoe shaped opacities aka riders
209
Q

Types of congenital cataracts

A 
Polar
Sutural
Coronary
Cerulean
Capsular
Membranous
Complete
210
Q

Characteristics of posterior polar cataract

A 
More decrease in vision
Larger
Closer to nodal point
If familial - AD and bilatetal
If sporadic - unilateral, may be assoc with PFV
211
Q

Characteristics of anterior polar cataract

A

Small bilateral
Symmetric
Non progressive
Usually no visual impairement
Usu congenital and sporadic but may be AD
May be associated with microphthalmos, PFV, anterior lenticonus
No treatment

212
Q

Characteristics of Sutural cataract

A

Usually doesn’t impair vision
Bilateral symmetric
AD

213
Q

Characteristics of Coronary cataracts

A 
Club shaped cortical opacities
Arranged like crown
Seen when dilated
No effect on VA
AD

CORONA

214
Q

Characteristics of Cerulean cataracts

A

Blue dot cataracts
Non progressive
No visual sx

215
Q

Characteristics of capsular cataract

A

Does not affect VA very much
Involves lens epithelium and cortex
Protrudes into AC

216
Q

Characteristics of capsular cataract

A

Does not affect VA very much
Involves lens epithelium and cortex
Protrudes into AC

217
Q

Characteristics of complete cataract

A

Total cataract

218
Q

Characteristics of membranous cataract

A

Lens CHON absorbed from intact or traumatized lens

Anterior and posterior capsule fuse. Into white membrane

219
Q

What is a rubella cataract?

A

White nuclear opacification
Insult at 1st trimester
Virus may be live until 3 yrs
Cataract sx complicated by excessive post op inflammation

220
Q

Difference of subluxated vs dislocated or luxated lens

A

Subluxated is still in pupillary area

Dislocated is displaced from pupil

221
Q

Symptoms of ectopia lentis

A

Dec vision
Astigmatism
Monocular diplopia
Iridodonesis

222
Q

Causes of ectopia lentis

A

Trauma

Marfan
Aniridia
Congenital glau
Homocystinuria

Also in
Ehlers Danlos
Hyperlysinemia
Weill Marchesani
Sulfite oxidase deficiency
223
Q

Characteristics of Marfan syndrome

A

AD
Fibrillin gene on chromosome 15
Ocular, CV and skeletal abnormalities

224
Q

Ocular problems in Marfan

A

50 to 80% with ectopia lentis, bilateral and symmetric
Zonules intact but stretched and elongated
Ectopia lentis usually congenital but subluxation may progress
Inc risk for axial myopia and RD

225
Q

Problems to be anticipated for lens surgery in patients with Marfan syndrome

A

Inc vit loss
RD

Prepare CTR

226
Q

What is Homocystinuria?

A

AR

Inborn error of methionine metabolism

227
Q

Facies and symptoms of Homocystinuria

A

Tall with light hair

Seizures
Osteoporosis
Cognitive impairment
Venous thromboembolism

228
Q

Ocular problems in homocystinuria

A

Bilateral symmetric lens dislocation
30% in infanct
80% by 15 years
Inferonasal direction

Due to cysteine disrupting zonules

229
Q

Management of Homocystinuria

A

Decrease methionine in diet

Supplement vitamin B6 and cysteine

230
Q

Features of hyperlysinemia

A

Ectopia lentis
Cognitive impairment
Muscular hypotony

Lysinemia lalamyalamya lens

231
Q

Gene associated with cortical cataracts

A

EHPA2 in IP36

50% inherited

232
Q

What is the Greek and Roman Emmanation Theory of Vision?

A

Optic nerve as passageway of visual spirits

Initially lens was thought to be at the center of the globe

233
Q

In 25BC to 50AD, who thought that the lens is at the center of the globe with a locus vacuus (empty space)

A

Celsus

Celsus rhymes with vacuus

234
Q

Who first said that the retina is responsible for sight?

A

Fabricus Ab Aquapendente - Italian anatomist

Felix Plater - Swiss physician

235
Q

Findings of the Salisbury Eye evaluation

A

Nuclear cataract - 50.7% in Caucasians, 33.5% in AfAm (more cortical)

236
Q

Findings of the Barbados research

A

Cortical MC in Blacks

Barbados blacks

237
Q

Cataract in smokers

A

Nuclear sclerotic

PSC

238
Q

Interdigitations of the apical cell and basal cell processes form the (posterior, anterior) sutures respectively

A

Anterior

Posterior

239
Q

Changes of epithelial lens cells as they elongate to become lens fibers

A

Increase mass of cellular proteins
Loose organelles
Become glycolysis dependent

240
Q

What is the germinative zone?

A

Area of lens with greatest Mitotic activity

A ring around anterior lens

241
Q

Describe the pump leak theory

A

K and AA actively pumped into anterior lens but they diffuse at the back

Na flows through the back and is actively exchanged for potassium by the epithelium

242
Q

What is the goal of lens metabolism

A

Maintain lens transparency

243
Q

What is the enzyme that phosphorylates glucose before it enters 3 metabolic pathways?

A

Hexokinase

70 to 100x slower than other enzymes in glycolysis (rate limiting step)

244
Q

Fate of G6P

A

Anaerobic glycolysis, more active, produces high energy phosphate bonds
HMP, less active (<5%, stimulated by Hugh glucose)

245
Q

Where does nonphosphorylated glucose go?

A

Sorbitol pathway

Enzyme - aldose reductase
Produces gluconic acid
Less than 4% usually converted to sorbitol

246
Q

What is the rate limiting enzyme in glycolysis?

A

Phosphofructokinase
Step 3 of 10
Regulated by feedback control by metabolic products of glycolytic pathway
Anaerobic is much less efficient vs aerobic
Low O2 tension in lens: only 3% passes through TCA but enough to produce 25% of ATP

247
Q

True or false

The lens is dependent on O2

A

False

Not dependent on O2
Completely transparent with ample glucose and normal ATP

248
Q

How does the sorbitol pathway affect cataract formation in patients with high glucose?

A

High glucose, sorbitol pathway activation
Sorbitol is metabolised to fructose by polyol dehydrogenase but this has low affinity, hence it will accumulate before it is metabolized
With high NADPH to NADH ratio, sorbitol accumulates leading to high NADP and activation of HMP
High fructose and glucose causes water retention in lens

249
Q

What stimulates the accommodative response?

A

Blur
Chromatic aberration
Continuous oscillation of ciliary tone

250
Q

From what structure is the lens capsule formed?

A

Basement membrane of epithelium and lens fibers

251
Q

True or false

Y sutures are erect anteriorly and inverted posteriorly

A

True

Develops at 8 weeks

252
Q

When do secondary lens fibers form?

A

Between 2 to 8 mos

2 mos secondary

253
Q

What happens at 25 days AOG?

A

2 lateral evaginations from forebrain or diencephalon form the optic vesicles. These enlarge and come to contact with the surface ectoderm.

254
Q

What is the lens placode?

A

Ectoderm cells overlying the optic vesicle that become columnar

Require BMP

255
Q

When are primary lens fibers completed?

A

At 35 days

Embryonic nucleus formed at 40 days

256
Q

When is the lens vesicle formed from the lens pit?

A

30 to 33 days

Same time as optic cup

257
Q

Localised cone shaped deformation of the anterior or posterior lens surface.

Associations?

Findings?

A

Lenticonus

Alport

Distorted and myopic reflex on retinoscopy

258
Q

Localised spherical deformation of lens

A

Lentiglobus

Posterior more common
Associated with posterior polar opacities

259
Q

Type 1 vs type 2 Peters anomaly

A

Type 1
Iris strands
Absent separation at 33 days

Tupe 2
Lens adherent to cornea
Assoc with anterior cortical or polar cataract
Misshapen lens
Microspherophakia
260
Q

What are bladder cells?

A

Cells in PSC

261
Q

Used for mild to moderate hyperopia with minimal astigmatism and presbyopia in the non-dominant eye

A

Conductive keratoplasty

C.EyeMD (8 decks)

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