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Ophthalmology > BCSC Lens and Cataract > Flashcards

BCSC Lens and Cataract Flashcards

1
Q

What are the functions of the crystalline lens?

A

1) to maintain its own clarity
2) to refract light
3) to provide accomodation

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2
Q

Does the lens have a blood supply after fetal development?

A

No. It depends on the aqueous to meet its metabolic requirements.

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3
Q

What are the basic components of the lens?

A

1) capsule
2) lens epithelium
3) cortex
4) nucleus

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4
Q

What is the equator of the lens?

A

The greatest circumference in the coronal plane

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5
Q

What amount of refractive power does the lens contribute to the eye?

A

15-20D (of the 60D total, the other 40-45 is provided by the cornea)

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6
Q

Does the lens continue to grow throughout life?

A

Yes

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7
Q

What is the diameter of the equator of the lens at birth?

A

6.4mm

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8
Q

What is the diameter of the equator of the lens in an adult eye?

A

9mm

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9
Q

How does the shape of the lens change with age?

A

It becomes more curved, giving it more refractive power

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10
Q

Of what is the lens capsule composed?

A

Type IV collagen laid down as a basement membrane by the lens epithelial cells

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11
Q

What is the zonular lamella?

A

the outer layer of the lens capsule, which serves as the point of attachment for the zonular fibers

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12
Q

Where is the lens capsule thickest?

A

anterior and posterior preequatorial zones of the lens

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13
Q

Where is the lens capsule thinnest?

A

the central posterior pole of the lens

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14
Q

Of what do zonular fibers consist?

A

microfibrils of elastic tissue

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15
Q

From where do the zonules originate?

A

From the basal laminae of the nonpigmented epithelium of the pars plana and pars plicata of the ciliary body

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16
Q

Where do the zonular fibers insert on the lens capsule?

A

in the equatorial region (1.5mm anterior to equator and 1.25mm posterior to the equator)

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17
Q

How many layers of epithelial cells are beneath the anterior lens capsule?

A

Only one

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18
Q

What is the germinative zone of the lens?

A

a ring of epithelial cells in the anterior equatorial lens that have high rates of mitotic activity

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19
Q

To where do newly formed lens epithelial cells (in the germinative zone) migrate?

A

Toward the equator, where the epithelial cells differentiate into fibers

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20
Q

What is the bow region of the lens?

A

The region where newly formed epithelial cells that have differentiated into fibers subsequently terminally differentiate into lens (cortical) fibers. This region is deep to the epithelium.

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21
Q

Are cells lost from the lens?

A

No

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22
Q

Where are the oldest fibers within the lens?

A

In the center of the lens

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23
Q

What are the oldest fibers in the lens?

A

The embryonic and fetal lens nuclei

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24
Q

What are the lens sutures?

A

The Y-shaped patterns formed by the interdigitations of apical cell processes anteriorly and posteriorly. They are visible at the slit-lamp.

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25
Q

Is the concentration of protein in the lens higher or lower than that of most other tissues in the body?

A

Higher – about 2x as much as most other tissues (33% of its wet weight).

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26
Q

What are the predominant proteins found in the lens?

A

Crystallins (alpha, beta, gamma)

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27
Q

What percentage of lens proteins is water soluble?

A

80% (the crystallins)

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28
Q

Into which groups are the water-insoluble lens proteins commonly divided?

A

Urea soluble and urea insoluble

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29
Q

Which water insoluble proteins are urea soluble?

A

Most cytoskeletal proteins

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30
Q

Which water insoluble proteins are urea insoluble?

A

Most lens fiber cell membrane proteins, including major intrinsic protein.

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31
Q

How does protein aggregation affect lens translucency?

A

Protein aggregation increases light scatter, creating lens opacities. Protein aggregation increases with age.

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32
Q

With what does the degree of opacification correlate in brunescent cataracts?

A

The proportion of water-insoluble protein

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33
Q

To what does depletion of reduced glutathione lead?

A

accelerated protein cross-linking, protein aggregation, and light scattering

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34
Q

On what does energy production in the lens primarily rely?

A

glucose metabolism

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35
Q

Which pathway is responsible for most of the high-energy phosphate bonds required for lens metabolism?

A

anaerobic glycolysis

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36
Q

Does the lens require oxygen for normal metabolism?

A

No. However, aerobic metabolism does occur naturally in the lens despite the low oxygen tension in the lens, and is responsible for 25% of the ATP generated.

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37
Q

What happens to glucose that is not phosphorylated to G6P in the lens?

A

it enters the sorbitol pathway or is converted to gluconic acid

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38
Q

What does the accumulation of sorbitol (as seen in hyperglycemic states) cause in the lens?

A

Increase in osmotic pressure, drawing in water

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39
Q

What type of cataract is typically formed as a result of long-term hyperbaric oxygen therapy?

A

Nuclear sclerotic

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40
Q

Which molecules serve as free radical scavengers?

A

glutathione, catalase, superoxide dismutase

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41
Q

How is communication between older cells and younger cells in the lens accomplished?

A

Through low-resistance gap junctions that facilitate the exchange of small molecules from cell to cell

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42
Q

Is disruption of water and electrolyte balance a feature of nuclear cataracts?

A

No, but it is a feature of cortical cataracts

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43
Q

Does the lens have higher or lower levels of potassium ions (K+) than its surrounding aqueous and vitreous?

A

Higher

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44
Q

Is active transport required for maintenance of lens ionic balance?

A

Yes, via the Na/K/ATPase pump

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45
Q

What is the primary site of active transport in the lens?

A

the epithelium

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46
Q

Does zonular tension increase or decrease with accommodation?

A

decrease

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47
Q

Does the ciliary body contract or relax during accommodation?

A

Contract

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48
Q

Which surface of the lens (anterior or posterior) changes in curvature to a greater extent during accommodation?

A

the anterior surface of the lens

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49
Q

What is the amplitude of accommodation?

A

The amount of change in the eye’s refractive power that is produced by accommodation

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50
Q

At which day of gestation does formation of the lens begin?

A

25 days

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51
Q

The lens capsule develops as a basement membrane elaborated by what?

A

The lens epithelium anteriorly and the lens fibers posteriorly

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52
Q

What are the primary lens fibers?

A

The fibers that make up the embryonic lens nucleus, which will occupy the center of the lens in adult life

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53
Q

The fetal nucleus is comprised of what?

A

The secondary lens fibers, which are formed between 2 and 8 months of gestation

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54
Q

Is the upright Y-suture anterior or posterior within the lens?

A

Anterior

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55
Q

What is the mass of the lens at birth?

A

90mg

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56
Q

What is the rate of increase in lens mass per year?

A

2mg per year

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57
Q

What is the tunica vasculosa lentis?

A

a network of capillaries arising frmo the hyaloid artery that anatomose with a second network of capillaries (the anterior pupillary membrane) to envelop the lens

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58
Q

What is a Mittendorf dot?

A

a remnant of the tunica vasculosa lentis (on the posterior aspect of the lens)

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59
Q

What is a persistent pupillary membrane?

A

a remnant of the anterior pupillary membrane (on the anterior aspect of the lens)

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60
Q

By what are the zonules of Zinn secreted?

A

By the ciliary epithelium

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61
Q

In which form of congenital aphakia is the lens spontaneously absorbed?

A

secondary aphakia

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62
Q

Which form of lenticonus is more common – anterior or posterior?

A

Posterior

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63
Q

With what is anterior lenticonus often associated?

A

Alport syndrome

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64
Q

Are zonular attachments in the region of a lens coloboma usually weak?

A

Yes, weak or absent

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65
Q

What does the site of a Mittendorf dot indicate?

A

the location at which the hyaloid artery came into contact with the posterior surface of the lens in utero

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66
Q

Which embryologic event fails to happen in Peters anomaly?

A

separation of the lens vesicle from the surface ectoderm

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67
Q

Peters anomaly is a part of what spectrum of disorders?

A

anterior segment dysgenesis syndromes

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68
Q

What are the clinical characteristics of microspherophakia?

A

small diameter lens that is spherical in shape

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69
Q

What refractive error is generally seen in microspherophakia?

A

high myopia

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70
Q

What are common lens findings seen in Peters anomaly?

A

1) adhesions between lens and cornea
2) anterior cortical or polar cataract
3) misshapen lens displaced anteriorly into the pupillary space and the anterior chamber
4) microspherophakia

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71
Q

What is the most common association of microspherophakia?

A

Weill-Marchesani syndrome (AR)

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72
Q

What are the syndrome associations of microspherophakia other than Weill-Marchesani syndrome?

A

1) Peters anomaly
2) Marfan syndrome
3) Alport syndrome
4) congenital rubella

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73
Q

What type of glaucoma can occur in patients with microspherophakia?

A

Secondary angle closure glaucoma due to pupillary block by the round lens

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74
Q

Which types of cataracts are often seen in aniridia?

A

cortical, subcapsular, and lamellar

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75
Q

Within what period of time must a cataract be present to be termed a congenital cataract?

A

within the first year of life

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76
Q

What is the appearance of a lamellar cataract when viewed from the front?

A

disc-shaped

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77
Q

What is the most common form type of congenital cataract?

A

Lamellar cataract

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78
Q

In what pattern are anterior polar cataracts usually inherited?

A

Autosomal dominant

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79
Q

Where are the bluish opacities generally seen in a cerulean cataract?

A

In the lens cortex

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80
Q

Is a subluxated lens separated from all its zonular attachments?

A

No, but a luxated lens is.

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81
Q

What is the most common cause of acquired lens displacement?

A

Trauma

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82
Q

What are common non-traumatic causes of ectopia lentis?

A

1) Marfan syndrome, 2) homocystinuria, 3) aniridia, 4) congenital glaucoma

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83
Q

What is the usual direction of lens dislocation in Marfan syndrome?

A

Superotemporal

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84
Q

What is the usual direction of lens dislocation in homocystinuria?

A

Inferonasal

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85
Q

Do nuclear cataracts typically cause greater impairment of distance vision or near vision?

A

distance vision

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86
Q

What are the first signs of cortical cataract formation visible with the slit-lamp?

A

vacuoles and water clefts in the anterior or posterior cortex

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87
Q

What is a sign that a cataract is hypermature?

A

wrinkling and shrinking of the lens capsule (due to leakage of degenerated cortical material through the capsule)

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88
Q

What is a morgagnian cataract?

A

a hypermature cataract with such a high degree of cortical liquefaction that the nucleus is able to move freely within the capsular bag (and is often displaced)

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89
Q

What is generally the first sign of PSC formation?

A

iridescent sheen in the posterior cortical layers visible with slit lamp

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90
Q

What are Wedl (bladder) cells?

A

aberrantly enlarged lens epithelial cells that have migrated posteriorly from the lens equator seen in PSC cataracts

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91
Q

What is seen in the later stages of a PSC cataract?

A

granular opacities of the posterior subcapsular cortex

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92
Q

What are common associations of PSC cataracts?

A

1) trauma, 2) steroids, 3) ionizing radiation, 4) alcoholism

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93
Q

Can steroid induced PSC cataracts resolve after discontinuation of the drug in children?

A

Yes, in children, but generally not in adults

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94
Q

Can PSC cataracts due to steroids be distinguished from those due to aging on histology?

A

No

95
Q

What is the typical appearance of cataracts caused by phenothiazines?

A

anterior spokes emanating from the visual axis (although usually visually insignificant)

96
Q

What is the typical early appearance of a cataract caused by an anticholinesterase?

A

anterior cortical vacuoles

97
Q

What percentage of patients using pilocarpine for > 55 months experience cataract formation?

A

20%

98
Q

What pattern of cataract is typically caused by amiodarone use?

A

stellate pigment deposition in anterior cortex

99
Q

What is a Vossius ring

A

a ring of pigment from the pupillary ruff imprinted on the anterior surface of the lens after blunt impact

100
Q

What is the initial manifestation of a cataract due to blunt injury?

A

stellate or rosette-shaped opacification (rosette cataract)

101
Q

Where does opacification generally occur in penetrating injury to the lens?

A

focal cortical opacification, which often progresses to complete cortical opacification

102
Q

What type of cataract is associated with true (glassblower/infrared radiation) exfoliation syndrome?

A

cortical cataract, with peeling off (exfoliation) of the lens capsule as a single layer

103
Q

For what percentage of risk of cortical cataracts does UV radiation account?

A

10%

104
Q

What is siderosis bulbi?

A

The deposition of iron molecules in TM, lens epithelium, iris, and retina due to iron-containing intraocular foreign body

105
Q

What kind of cataract can be formed due to intraocular copper-containing foreign body?

A

Sunflower cataract

106
Q

With which other findings is a sunflower cataract in chalcosis usually associated?

A

deposition of copper in Descemet membrane, iris heterochromia

107
Q

What findings can be seen in cataract due to electrical injury?

A

Anterior mid-peripheral cortical vacuoles and linear opacities in anterior subcapsular cortex

108
Q

What is the typical pattern of an acute diabetic cataract?

A

“Snowflake” pattern, consisting of bilateral widespread subcapsular gray-white opacities (anteriorly and posteriorly)

109
Q

Do age-related cataracts occur earlier or later in patients with diabetes than in the general population?

A

earlier in DM

110
Q

Which enzyme is the most commonly implicated in galactosemia?

A

G1P-UT (galactose 1-phosphate uridyltransferase)

111
Q

What is the typical appearance of a cataract in galactosemia?

A

“oil-droplet” appearance, with opacification of the nucleus and deep cortex

112
Q

What is the typical pattern of a hypocalcemic cataract?

A

Punctate iridescent opacities in anterior and posterior cortex

113
Q

What is the typical pattern of a cataract in Wilson disease?

A

Sunflower cataract (also seen in copper-containing IOFB)

114
Q

What is the typical pattern of lens opacification seen in myotonic dystrophy?

A

polychromatic iridescent crystals (whorls of cell membranes) in lens cortex followed by PSC

115
Q

What is the typical pattern of lens opacification seen in Fuchs heterochromic iridocyclitis?

A

cortical cataract

116
Q

What type of cataract is seen in patients undergoing hyperbaric oxygen therapy?

A

Nuclear sclerotic cataract (often with associated myopic shift)

117
Q

What is the typical pattern of cataract seen in atopic dermatitis?

A

shield-like anterior subcapsular opacities, occurring usually in the 2nd to 3rd decade of life

118
Q

What is commonly the trigger for phacoantigenic uveitis?

A

The release of a large amount of lens protein into the AC, disrupting immunologic tolerance and causing a severe inflammatory reaction.

119
Q

What is the mechanism of phacolytic glaucoma?

A

leakage of liquefied HMW lens proteins through an intact but permeable lens capsule (usually with mature or hypermature cataract) –> blockage of TM by engorged macrophages

120
Q

Is phacolytic glaucoma an open or closed angle glaucoma?

A

Open

121
Q

Is the onset of pain in phacolytic glaucoma gradual or abrupt?

A

Usually abrupt, despite having an open angle.

122
Q

What is the mechanism of lens particle glaucoma?

A

blockage of the TM by lens material (usually after phaco or penetrating trauma)

123
Q

Is the angle usually open or closed in lens particle glaucoma?

A

Open

124
Q

What is the usual delay in onset of lens particle glaucoma after penetrating trauma or surgery?

A

days to weeks

125
Q

What is the mechanism of phacomorphic glaucoma?

A

Intumescent cataractous lens (or other abnormally shaped lens) causes pupillary block and secondary angle closure (or pushes the iris forward and causes a narrow angle)

126
Q

Is phacomorphic glaucoma an open or closed angle glaucoma?

A

A closed/narrow angle glaucoma

127
Q

What are glaucomflecken?

A

Necrotic lens epithelial cells and degenerated subepithelial cortex that present as gray-white opacities in anterior lens after episode of high IOP

128
Q

What percent of blindness is thought to be reversible blindness due to cataracts worldwide?

A

48% (17 million individuals)

129
Q

Do smokers have an increased risk of developing nuclear lens opacities?

A

Yes

130
Q

Do PSC cataracts have a greater impact on near or distance visual acuity?

A

Near visual acuity

131
Q

Do oil droplet cataracts have a greater impact on near or distance visual acuity?

A

Distance visual acuity (they cause a myopic shift)

132
Q

Which medications are associated with intraoperative floppy iris syndrome (IFIS)?

A

alpha1a-adrenergic antagonists (prazosin, terazosin, doxazosin, tamsulosin)

133
Q

For how long before cataract surgery should an eye ideally be quiet without the use of topical corticosteroids?

A

3 months

134
Q

Can dilation improve visual acuity in patients with cataracts?

A

Yes, especially in those with PSCs

135
Q

If ACIOL implantation is anticipated, what needs to be done as part of the pre-operative evaluation that otherwise might not be done?

A

Gonioscopy

136
Q

What form of evaluation of the posterior segment is warranted in the pre-operative evaluation of a dense white cataract?

A

B-scan ultrasonography

137
Q

In patients with high hyperopia, compression of the eye by 1mm during contact applanation A-scan ultrasonography can result in how large an error in IOL power?

A

3.75 diopters error

138
Q

What is “white to white” distance?

A

A term commonly used to refer to corneal diameter

139
Q

What features of endothelial cells on specular microscopy may indicate a propensity for corneal decompensation after cataract surgery?

A

Polymegathism (varying degrees of enlargement) and polymorphism (varying shapes)

140
Q

Are measurements of corneal power and axial length required to determine IOL power when using intraoperative aberrometry?

A

No

141
Q

What is the axial length of the eye when used in IOL calculations?

A

The distance from the anterior surface of the cornea to the fovea

142
Q

What is an A constant?

A

A dimensionless constant relating the power of a particular IOL to axial length and keratometry

143
Q

What is the SRK formula for IOL power prediction to achieve emmetropia?

A

P = A - (2.5L) - 0.9K

P is the IOL power
A is the A-constant of the specific IOL used
L is the axial length of the eye
K is the average keratometric reading in diopters

144
Q

What are three common types of methods for calculating corneal power for IOL prediction in a patient who has undergone refractive surgery?

A

1) Contact lens method
2) Topographical method
3) Historical method

145
Q

How is corneal power determined by the contact lens method?

A

K = base curve + power + overrefraction - spherical equivalent of MRx without CL

146
Q

How is corneal power determined by the topographical method?

A

central keratometric power = [central topographic power * (376/337.5)] - 4.9

147
Q

How is corneal power determined by the (Hoffer) historical method?

A 
K2 = K1 + SE_1 - SE_2
K1 = K before refractive surgery
SE_1 = spherical equivalent refractive error before refractive surgery
SE_2 = spherical equivalent refractive error after refractive surgery
148
Q

What does modern extracapsular cataract extraction (ECCE) involve?

A

removal of the lens nucleus and cortex through an opening in the anterior capsule, with the capsular bag left in place

149
Q

What are the advantages of manual small incision cataract surgery (MSICS) over ECCE?

A

smaller scleral groove (7-8mm vs. 12-14mm); CCC instead of can-opener rhexis; wound suturing is optional; lens may be expressed in pieces rather than whole

150
Q

What does OVD stand for?

A

Ophthalmic Viscosurgical Device

151
Q

What are the common components of OVDs (viscoelastics)?

A

1) sodium hyaluronate, 2) chondroitin sulfate, 3) hydroxypropyl methylcellulose

152
Q

What is the half-life of sodium hyaluronate in the AC?

A

1 day in aqueous (3 days in vitreous)

153
Q

From what is chondroitin sulfate usually obtained?

A

Shark cartilage

154
Q

What does viscoelasticity mean?

A

It refers to the ability of a compound to act as a viscous agent when imparted with low frequency energy and as an elastic agent (or gel) when imparted with high frequency energy

155
Q

What is pseduoplasticity?

A

the ability of a substance to transform from a gel to a liquid-like substance when under pressure (e.g. be forced through a cannula while maintaining shape in AC)

156
Q

Does a viscoelastic with high surface tension coat substance more or less effectively than one with low surface tension?

A

less effectively. Low surface tension –> better coating, but harder to remove from eye

157
Q

What are examples of cohesive viscoelastics?

A

Healon, Healon GV, Amvisc

158
Q

What are examples of dispersive viscoelastics?

A

Ocucoat, Viscoat, Healon Endocoat

159
Q

Do dispersive viscoelastics have high or low surface tension?

A

Low surface tension

160
Q

Who described the modern technique of retrobulbar anesthesia?

A

Atkinson

161
Q

What are the two key results of retrobulbar anesthesia?

A

Ocular akinesia and anesthesia

162
Q

Where is anesthetic solution introduced in peribulbar anesthesia?

A

external to the muscle cone, underneath Tenon capsule

163
Q

Which nerves are blocked by retrobulbar anesthesia?

A

Ciliary nerves, CN II, CN III, and CN VI

164
Q

What are advantages of topical anesthesia for cataract surgery?

A

1) no risk of ocular perforation/EOM injury/CNS depression

2) vision returns almost immediately

165
Q

What are disadvantages of topical anesthesia for cataract surgery?

A

1) increased extracoular motility
2) blepharospasm
3) patient discomfort

166
Q

What is cavitation?

A

The formation of gas bubbles in the aqueous in response to pressure changes at the tip of the phaco needle. The implosion of these bubbles results in heat and pressure liberation at the phaco tip, resulting in emulsification of lens material

167
Q

What is chatter?

A

The back and forth movement of lens material at the phaco tip due to vacuum that is repeatedly overcome by the ultrasonic stroke of the phaco tip

168
Q

What is phaco duty cycle?

A

The proportion of time during which phaco energy is being delivered in pulsed phacoemulsification

169
Q

What is the common range of frequencies (of needle movement) for ultrasonic phaco handpieces?

A

27,000 Hz to 60,000 Hz

170
Q

To what does “load” refer in ultrasonics?

A

The mass of nuclear material in contact with the phaco tip

171
Q

How is power denoted in ultrasonics?

A

As a percentage of the maximum stroke length of which the needle is capable

172
Q

What is “stroke” in ultrasonics?

A

the linear displacement of the phaco tip; it commonly varies from 0.05-0.1mm

173
Q

What are the commonly used dimensions for aspiration flow rate?

A

mL/min

174
Q

What is followability?

A

the ability of a system to attract and hold an object at the end of a handpiece

175
Q

What is “occlusion” in vacuum terminology?

A

obstruction of the aspiration port, which leads to a build-up of vacuum until the obstructing material is evacuated

176
Q

What is “rise time” in vacuum terminology?

A

The rate at which vacuum builds once occlusion of the aspiration port is achieved

177
Q

What is “surge” in vacuum terminology?

A

The phenomenon of abrupt drawing of intraocular contents to the aspiration tip after vacuum has built up due to occlusion and the occlusion is subsequently broken

178
Q

How is vacuum generally measured?

A

mmHg. It indicates how well material occluding the phaco tip will be held to the tip

179
Q

What is “venting” in vacuum terminology?

A

The process by which negative pressure is equalized to atmospheric levels to prevent surge

180
Q

What is set during pulsed-mode phacoemulsification?

A

The number of pulses per second (each pulse is followed by an equivalent interval without delivery of phaco power). Phaco power varies with foot pedal excursion (0-100%, or less than 100% upper limit if desired).

181
Q

What is set during burst-mode phacoemulsification?

A

The amount of phaco power delivered (0-100%). The interval between bursts decreases with increasing foot pedal excursion (but a lower limit can be set on this interval).

182
Q

To what is burst-mode phacoemulsification equivalent if the interval between bursts goes to 0?

A

continuous mode phacoemulsification

183
Q

For what is burst mode phacoemulsification particularly useful?

A

burying the phaco tip into the lens, which is necessary for chopping techniques

184
Q

What are the 3 types of aspiration pumps used in phaco machines?

A

1) Peristaltic
2) Diaphragm
3) Venturi

185
Q

Traditionally, which type of aspiration pump has provided the fastest and most linear rise in vacuum?

A

Venturi pump

186
Q

What is the usual distance (in clock hours) between a main incision and paracentesis?

A

2 to 3 clock hours

187
Q

What are risks of making a small capsulorrhexis?

A

1) Difficulty in disassembling the lens

2) Possibility of capsular phimosis

188
Q

What are risks of making a large capsulorrhexis?

A

1) Difficulty in performing endocapsular phaco techniques

2) Possibility of anterior dislocation of the IOL optic or haptic

189
Q

What size capsulorrhexis is often advocated?

A

One that allows the capsular rim to cover the optic edge

190
Q

What is the primary role that OVD plays in performing the CCC?

A

Keeping the lens flat to avoid radialization of the tear

191
Q

What two crystalline lens components does hydrodelineation separate?

A

Hydrodelineation separates endonucleus from the softer epinucleus

192
Q

Is hydrodelineation useful in white or densely brunescent nuclei?

A

Not usually

193
Q

What is lens sculpting?

A

The process of debulking the central nucleus. It involves a shaving maneuver in which the tip of the phaco needle is never fully occluded.

194
Q

What are the locations traditionally used for phacoemulsification?

A

1) Anterior Chamber
2) Iris plane
3) Posterior chamber
4) Supracapsular

195
Q

What are common indications that adequate depth has been achieved with the sculpting of the central groove in the divide and conquer technique?

A

1) smoothing of striations in the groove
2) brightening of the red reflex in the groove
3) sculpting to a depth of 2 to 3 phaco tip diameters

196
Q

For which type of cataracts is chopping generally not helpful?

A

Soft cataracts, such as pure PSC cataracts

197
Q

What are some techniques for aspiration of subincisional cortex?

A

1) Use of a 45 degree, 90 degree, or U-shaped aspiration cannula
2) introduction of a separate aspiration port via the paracentesis instead of the main incision
3) viscodissection
4) loosening of cortex with IOL haptics

198
Q

Is cataract surgery considered to be an invasive procedure that induces transient bacteremia?

A

No. Accordingly, systemic antibiotic prophylaxis is not required.

199
Q

What percent of cataract surgeries result in bacterial innoculation of the anterior chamber?

A

7-35%

200
Q

Intracameral injection of what medication has been shown to reduce the risk of endophthalmitis after cataract surgery?

A

Cefuroxime (ESCRS Endophthalmitis Study Group; J Cataract Refract Surg 2006 Mar;32(3): 407–10)

201
Q

Has definitive evidence been obtained indicating that use of topical antibiotics after cataract surgery reduces risk of endophthalmitis?

A

No

202
Q

By how much is the astigmatic correction reduced for every degree of error in axis of a toric IOL?

A

3% for each degree

203
Q

What can occur if silicone oil is used in a pseudophakic patient with a silicone IOL?

A

Adhesion of droplets of silicone oil to the IOL

204
Q

What are disadvantages of traditional multifocal IOLs?

A

1) reduction in contrast sensitivity
2) Decrease in BVCA
3) Increased glare
4) Increased haloes

205
Q

What is range of rates of posterior capsular or zonular rupture in cataract surgery?

A

1.5% to 3.5%

206
Q

What is the rate of vitreous loss/anterior vitrectomy or aspiration in cataract surgery?

A

1.1%

207
Q

What is the range of rates of postoperative CME in cataract surgery?

A

1.2% to 3.3%

208
Q

What is the range of rates of postoperative endophthalmitis in cataract surgery?

A

0.1% to 0.2%

209
Q

What is the likely cause of postoperative corneal epithelial edema in setting of compact stroma after cataract surgery?

A

elevated IOP

210
Q

What is Brown-McLean syndrome?

A

peripheral corneal edema with a clear central cornea after cataract surgery

211
Q

What happens to a cataract wound that experiences thermal injury from a phaco tip?

A

contraction of corneal collagen, wound gape, and leakage

212
Q

What are potential causes of detachment of Descemet membrane in cataract surgery?

A

1) insertion of instrument through the incision

2) inadvertent injection of fluid between Descemet membrane and stroma

213
Q

What usually happens in the meridian of the incision in cataract surgery?

A

flattening

214
Q

What are clinical signs of epithelial downgrowth?

A

elevated IOP, clumps of cells floating in the AC, visible retrocorneal membrane with overlying corneal edema, abnormal iris surface, pupillary distortion

215
Q

What is Toxic Anterior Segment Syndrome?

A

severe sterile postoperative intraocular inflammation and corneal edema due to entry of a toxic substance into the AC

216
Q

What are causes of elevated IOP without angle closure after cataract surgery?

A

1) retained OVD (peak 4-6 hours after surgery)
2) hyphema
3) TASS
4) endophthalmitis
5) retained lens material
6) uveitis
7) iris pigment release
8) pre-existing glaucoma
9) corticosteroid usage
10) vitreous in AC
11) ghost cell glaucoma
12) alpha-chymotrypsin

217
Q

What is the triad of Intraoperative Floppy Iris Syndrome (IFIS)?

A

1) iris billowing
2) iris prolapse into the incisions
3) progressive pupillary miosis

218
Q

Which drugs are most likely to be associated with IFIS?

A

Alpha 1-a adrenergic agonists (e.g., tamsulosin)

219
Q

What is Lens-Iris Diaphragm Retropulsion Syndrome (LIDRS)?

A

High infusion pressure in AC leading to reverse pupillary block. LIDRS is characterized by posterior displacement of the lens-iris diaphragm with marked deepening of the AC, posterior iris bowing, and pupil dilation.

220
Q

With which two bacterial pathogens has chronic uveitis following cataract surgery been associated?

A

Propionibacterium acnes and Staph epidermidis

221
Q

By what time after cataract surgery should an eye be free of inflammation with current topical regimens?

A

3-4 weeks after surgery

222
Q

Which is more likely to incite inflammation – retained cortical or nuclear material?

A

Nuclear material is more likely to incite infammation

223
Q

How long after initial cataract surgery is PPV for removal of dropped lens material usually performed?

A

7-14 days

224
Q

What can vitreous in the AC lead to?

A

Chronic intraocular inflammation with or without CME

225
Q

Which types of lenses were traditionally associated with UGH?

A

rigid or closed-loop anterior chamber IOLs

226
Q

What is the common description of a negative dysphotopsia?

A

Arcuate dark or dim region in the temporal visual field

227
Q

What is the etiology of posterior capsule opacification (PCO)?

A

Continued viability of lens epithelial cells after cataract surgery. Lens epithelial cells proliferate, forming secondary membranes.

228
Q

What are two common forms of proliferation of lens epithelial cells after cataract surgery?

A

1) Soemmering ring – donut-shaped configuration between the adherent edges of anterior and posterior capsule
2) Elschnig pearls – tranlucent globular masses resembling fish eggs on the edge of the capsular opening

229
Q

What type of medication has been seen to reduce PCO when instilled in the capsular bag?

A

Mitotic inhibitors

230
Q

What is the reported incidence of retinal detachment after YAG laser capsulotomy?

A

0.1% to 3.6%

231
Q

What is the time of onset of acute postop endophthalmitis in cataract surgery?

A

3 to 10 days

232
Q

When is PPV for endophthalmitis indicated per the Endophthalmitis Vitrectomy Study (EVS)?

A

If vision is LP or worse (if HM or better, tap and inject)

233
Q

What are the three most common causes of acute postoperative endophthalmitis in cataract surgery?

A

Staph epi, Staph aureus, Strep species

234
Q

How long after cataract surgery does CME typically occur?

A

6 to 10 weeks after surgery

Ophthalmology (14 decks)

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