Cornea Vol. 3 Flashcards Preview

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Flashcards in Cornea Vol. 3 Deck (24):
1

Histologically, what are conjunctival follicles?

Clusters of lymphocytes

2

What type of cells form "mutton-fat" KP?

Macrophages

3

Where are clusters of follicles located In benign lymphoid folliculosis?

lnferotemporal palpebral and forniceal conjunctiva

4

Where is the thinnest portion of the cornea typically located?

1.50 mm temporal to the geographic center

5

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

Greater than 650 um

6

What are Waite-Beet ham lines?

Faint, deep stromal wrinkles seen in early corneal edema

7

What is the average endothelial cell count in children?

3500 cells/mm2

8

What forms keratic precipitates (KP)?

Clumps of Inflammatory cells from the anterior uvea

9

What is the average endothelial cell count In adults?

2400 cells/mm2

10

What is the average endothelial cell size in adults?

150 to 350 um2

11

How is corneal endothelium coefficient of variation calculated?

Mean cell area divided by standard deviation of the cell area

12

What is the normal coefficient of variation of the cornea?

Less than 0.3

13

What is polymegethism?

Increased variation In individual cell areas of the cornea

14

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

Contacts lens use

15

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

Palisades of Vogt

16

When are Descemet's folds typically first seen?

When corneal thickness increases by 10% or more

17

What is the average refractive power of the cornea?

43 D

18

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

49 D

19

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

6 D

20

When does corneal epithelium edema occur?

When corneal thickness exceeds 0.70 mm

21

What is the average endothelial cell count In elderly patients?

2000 cells/mm2

22

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

Approx. 3D

23

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

Peripheral or "transitional" zone

24

What is Snell's law?

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