Exam 1 Remington- Cornea Flashcards Preview

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Flashcards in Exam 1 Remington- Cornea Deck (123)
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91

What is keratoconus?

Corneal dystrophy, caused is nutritional or metabolic

92

What is the initial disruption in keratoconus?

BM and Bowman's

93

Keratoconus eventually involves what?

Significant stromal thinning

94

What type of astigmatism does keratoconus produce?

Irregular astigmatism, cannot be corrected with spectacles

95

What may slow the progression of keratoconus?

RGP CL

96

What is Munson's sign in keratoconus?

Lower lid conforms to conic shape on down gaze

97

Currently clinical trials are evaluating collagen cross linking to what?

Slow disease progression

98

What is collagen cross linking?

Riboflavin saturates the cornea and is then activated by ultraviolet light, this increase cross linking between collagen fibrils thus strengthening the cornea and may arrest the progression of keratoconus

99

What is the cellular composition of Descemet's membrane?

Dense CT, acellular

100

What is the BM of corneal endothelium?

Descemet's membrane

101

Descemet's membrane is highly resistant to ______ ______

Proteolytic enzymes

102

Descemet's membrane has ________ properties

Elastic

103

What is the termination of Descemet's membrane in the corneal periphery?

Schwalbe's line

104

How are the cells in the endothelium arranged?

Regular arrangement = endothelial mosaic

105

What % of cells are hexagonal in the endothelium?

70-80%

106

The endothelium does not _______; cells just spread out. Cells appear to be in ______ state.

Replicate, arrested

107

What are the 4 intercellular junctions in the endothelium?

Lateral interdigitations, gap junctions, occluding junctions, and modified hemidesmosomes

108

What are occluding junctions?

"Slightly leaky" barrier

109

What are Hassall-Henle bodies?

Thickenings in Descemet's membrane, they are a normal physiological aging change

110

Guttata

Deposits in Descemet's membrane indicative of dysfunction

111

Dua's layer

Recent studies suggest that there is this collagenous layer between stroma and Descemet's membrane

112

What cells are Dua's layer composed of?

Acellular and composed primarily of collagen type 1

113

The presence of Dua's layer might be important for what?

Current corneal transplant procedures

114

Are there corneal BVs?

NO

115

Why are there no corneal BVs?

There may be an antiangiogenic agent present

116

What type of sensory innervation is in the cornea?

Dense

117

The cornea has about ____ times as many sensory fibers in the tissue than anywhere else in the body

400

118

How many bundles of axons enter the corneal periphery?

70-80

119

Fibers lose the myelin sheath within ___ mm into cornea

1-2

120

What is the innervation pattern of the cornea?

Stomal plexus, subepithelial plexus, intraepithelial plexus