Cornea Vol. 3 Flashcards

1
Q

Histologically, what are conjunctival follicles?

A

Clusters of lymphocytes

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2
Q

What type of cells form “mutton-fat” KP?

A

Macrophages

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3
Q

Where are clusters of follicles located In benign lymphoid folliculosis?

A

lnferotemporal palpebral and forniceal conjunctiva

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4
Q

Where is the thinnest portion of the cornea typically located?

A

1.50 mm temporal to the geographic center

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5
Q

What central corneal thickness increases the risk of symptomatic corneal edema following intraocular surgery?

A

Greater than 650 um

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6
Q

What are Waite-Beet ham lines?

A

Faint, deep stromal wrinkles seen in early corneal edema

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7
Q

What is the average endothelial cell count in children?

A

3500 cells/mm2

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8
Q

What forms keratic precipitates (KP)?

A

Clumps of Inflammatory cells from the anterior uvea

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9
Q

What is the average endothelial cell count In adults?

A

2400 cells/mm2

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10
Q

What is the average endothelial cell size in adults?

A

150 to 350 um2

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11
Q

How is corneal endothelium coefficient of variation calculated?

A

Mean cell area divided by standard deviation of the cell area

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12
Q

What is the normal coefficient of variation of the cornea?

A

Less than 0.3

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13
Q

What is polymegethism?

A

Increased variation In individual cell areas of the cornea

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14
Q

What is the most common cause of increased polymegathism of the cornea?

A

Contacts lens use

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15
Q

Where does corneal neovascularization typically originate in the limbal vascular arcades?

A

Palisades of Vogt

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16
Q

When are Descemet’s folds typically first seen?

A

When corneal thickness increases by 10% or more

17
Q

What is the average refractive power of the cornea?

A

43 D

18
Q

What is the refractive power of the air-stroma Interface?

A

49 D

19
Q

What is the refractive power of the endothelium? aqueous interface?

A

6 D

20
Q

When does corneal epithelium edema occur?

A

When corneal thickness exceeds 0.70 mm

21
Q

What is the average endothelial cell count In elderly patients?

A

2000 cells/mm2

22
Q

How many diopters is the central cornea typically steeper than the periphery?

A

Approx. 3D

23
Q

What part of the cornea is the area of greatest flattening and asphericity?

A

Peripheral or “transitional” zone

24
Q

What is Snell’s law?

A

Refractive power equals difference between two refractive indices divided by the radius of curvature