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1

corneal lens

common design for rigid/gp lenses, diameter of lens smaller than corea

2

ballasted lens

lens with a heavier base which becomes oriented inferiorly or downward when the lens is worn

3

stippling can result when

inadequate tear exchange

4

semi-scleral

typical of soft lenses, bridge limbus

5

PMMA

hard transparent plastic, conventional hard lenses

6

radius of curvature

distance from the geometric center of the circle to its periphery where the line is drawn

7

front surface toric lenses

anterior surface has 2 different radii, posterior surface spherical

8

5 layers of cornea front to back

epithelium, bowman's, stroma, descemet's, endothelium

9

against the rule astigmatism

horizontal meridian steepest, vertical flattest

10

measuring magnifier

peripheral curve width, optic zone width and lens diameter verified simultaneously

11

corneal vascularization

invasion of blood vessels in the cornea

12

parallelepiped

broader view of anterior + posterior corneal surfaces, assesses any surface irregularities

13

white filter (slit lamp)

decrease ultraviolet rays, decrease light intensity, used for routine examination

14

prolonged corneal edema can result in

photophobia, limbal injection, excessive spectacle blur

15

residual astigmatism can be corrected through the use of

bitoric lens

16

scleral lenses

1st successful contact lens, gp material, hard to tolerate

17

gas permeable

permits passage of oxygen + carbon dioxide thru lens

18

wetting angle

the angle that the edge of a bead of water makes with the surface of the plastic, the smaller the angle the greater the wetting ability

19

CAB

better gas permeability than PMMA, wets easier

20

silicone-acrylate (rigid lens)

35% silicone, 65% PMMA, more comfortable than CAB

21

dk value

a measure of the oxygen permeability through a given material

22

HEMA

soft lenses

23

bicurve lens

lens which contains two curves: one base curve and one secondary curve, intrapalpebral lenses, designed to fit within the palpebral fissure limits.

24

tricurve lens

lens which contains three curves: a base curve, an outer peripheral posterior curve, and an intermediate posterior curve

25

diopter to mm conversion

337.5/diopters

26

optic zone

the central zone that contains the refractive power

27

prism ballasted lens

a ballasted lens which utilizes a prism wedge designed to weight the lens

28

truncated lens

lens which has been cut off to form a horizontal base

29

back surface toric

posterior surface has 2 different radii, anterior surface spherical

30

bitoric

lens which both posterior + anterior surfaces contain 2 different radii

31

lenticular bowl

moon shaped, thicker in the center, thinner on sides

32

spin cast soft lens

liquid material manufactures soft lens to get desired curvature, design, power

33

lathe cut soft lens

manufacturing soft contact lenses in which a machine lathe is used to grind lens designs, size and power

34

first successful contact lenses

haptic

35

majority of soft lenses today

semi-scleral

36

cpc of rigid lens held constant while diameter increased

tighter fit

37

reason to use ballasted lens

inhibit lens rotation

38

distance between flat surface + back portion of a lens

sagittal depth

39

radius of curvature held constant while diameter is increased, vault of the lens will be

increased

40

function of tear film

maintain optical quality and health of the cornea + conjunctiva, provides oxygen when contacts are worn

41

lipid layer

prevents evaporation of tear film, produced by meibomian glands, top/outer layer

42

aqueous layer

middle layer, 98% water, accounts for most of thickness, produced by lacrimal glands

43

mucoid layer

bottom layer, produced by goblet cells, converts hydrophobic epithelial layer to hydrophillic

44

BUT

assesses quality of tear film

45

Schirmer test

assesses quantity of tear film with a strip of filter paper

46

keratometer

measures curvature of cornea

47

topogometer

attachment to make keratometer more accurate

48

placido's disk

assess regularity of the cornea

49

precorneal tear film provides

lubricant to the cornea, smooth optical surface, nutrients to cornea

50

with the rule astigmatism

vertical meridian steepest, horizontal flattest

51

shadowgraph

assess quality of peripheral curves

52

dynamic flourescein pattern best illuminated by

blue cobalt filter

53

radiuscope

measures curvature of contact lens

54

primary source of oxygen for the cornea is

tears

55

when a rigid lens shows apical touch, it indicates

flat fitting lens

56

ideal flourescein pattern for spherical lens on a spherical cornea would show

even distribution of flourescein, added thickness under peripheral curves

57

limbus

transition zone between sclera and cornea

58

corneal edema

swelling of the cornea

59

corneal epithelial edema

appears as a grey cornea and may be best observed with a slit lamp using sclerotic scatter

60

corneal striae

linear opacities in the cornea

61

GPC

formation of papillae on conjunctiva, more frequent in soft lens wearers

62

slit lamp

observes structures of the human eye

63

diffuse illumination

wide beam of unfocused light directed obliquely at the cornea, used for general survey of the eye. no fine details

64

direct focal illumination

focusing beam and the microscope in the same specific area, usually requiring increased magnification

65

optic section

used to see all layers of the cornea

66

conical beam

observes flare, high magnification

67

indirect illumination

microscope focused on area immediately adjacent to the illuminated position

68

retro illumination

light focused on deeper structures, while microscope is focused to study anterior structures reflected in the light, examines corneal edema, blood vessels

69

specular reflection

beam of light reflects from corneal surfaces and pass thru oculars of the microscope, observes elevations + depressions

70

sclerotic scatter

broad beam of light focused at temporal limbus, transilluminates thru to the nasal limbus, focuses on cornea, detects presence of corneal edema

71

cobalt filter (slit lamp)

observe staining patterns and lens fit

72

neutral density filter (slit lamp)

decreases light intensity by 10%, used to examine eyelids and conjunctiva

73

after four hours of wear, patient indicates that the lens feels hot, this may indicate

too tight lens

74

slit lamp illumination used for detecting corneal edema

sclerotic scatter and the naked eye

75

during a slit lamp evaluation, a hazy cornea is an indication of

corneal edema

76

superficial punctate staining at the corneal apex combined with edema in this region may indicate

a steep fit lens

77

during a slit lamp evaluation, certain areas of the cornea are observed which appear dark, retain their configuration during blinking and do not stain, these areas likely represent

dry spots

78

average pH of human tears

7.4

79

punctate staining generally a result of

inadequate tear exchange

80

arc shaped stain can be caused by

poor edge, not well rounded

81

corneal vascularization is most likely to occur with

PMMA lenses

82

piggyback lenses

used when patient cant tolerate rigid lenses, soft lens placed on cornea, rigid lens placed over it

83

contacts for correction of aphakia have advantages over glasses, including

less peripheral aberration, less magnification, increased visual field

84

bitoric lenses prescribed when

there is at least 1.50D of corneal astigmatism, significant amount of residual

85

early stages of keratoconus may be detected thru the use of

keratometer

86

hyperflange used for

high minus lenses

87

patient diagnosed with keratoconus may present what during slit lamp examination

thinning of corneal apex

88

spherical rgp lens fit on the cornea with a significant amount of with the rule astigmatism will show touch

along horizontal meridian

89

possible to extend the range of a keratometer to 61.00D through the use of a trial lens with a power of

+1.25D

90

power of bifocal lens changes gradually from the central area of the lens to periphery

aspherical lens

91

radiuscope

measures radius of curvature

92

profile analyzer

assessment of quality of peripheral curves

93

contact lens power should be specified in

back vertex power

94

when keratometric miers reflected off a soft contact lens are only clear when blinking, lens fit is

too steep

95

transient keratometric mier distortion is usually due to

preocular tear film abnormalities

96

flourescein pattern shows narrow bend horizontally with concentration of flourescein inferiorly and superiorly under the lens

with the rule astigmatism

97

RGP lens has 43.50 base curve and +2.75 power, -0.75 is refracted over the lens, ordering a new lens with a 43.00 base curve would get a power of

+2.50

98

what should be considered in fitting a keratoconus patient

aspheric, mcguire, soper

99

designs helpful in orienting high riding myopic lenses

hyperflange, prism ballast

100

age related signs of presbyopia

tear film abnormalities, reduce lid elasticity, lens opacities, pupil constriction

101

bifocal lens that may rotate without vision imparement

tangent streak

102

keratoconus and penetrating keratoplasty fittings best accomplished by

diagnostic fittings

103

K's 45.00@180/42.00@90 Rx -2.00-4.25x90, what rgp lens design would best correct the wearers vision

42.00/45.00 -2.00

104

segmented lens is a

translating bifocal

105

K's 42.50@180/42.50@90 Rx -3.00-1.00x90, what lens specification would best correct the vision

42.50-3.00-1.00x90

106

K's 42.00@180/45.00@90, Rx -3.00-2.25x180, what will best correct this vision

42.00/45.00-3.00-2.25x180

107

warped lens will show

2 base curves on radiuscope and spherical power on lensometer

108

precorneal tear films 3 layers

lipid, aqueous, mucin

109

what maintains the normal cornea being transparent due to pump action creating proper fluid balance

endothelium

110

normal cornea is in a state of

deturgesence

111

dense white appearance of entire peripheral circumference of the cornea and doesn't stain

arcus senilus

112

main focusing mechanism of the eye

crystalline lens

113

normal tear break up time

10-12 seconds

114

lenses that don't require a weekly cleaner

PMMA

115

clinical management of RGP flexure may be eliminated by

reducing sagittal vaulting, increasing center thickness, choosing lower Dk material

116

upon removal of crystalline lens, patient is

aphakic

117

RGP measures +15.00 BVP, FVP will measure

lesser dioptric reading

118

low riding high plus on a 40.00/40.75 cornea could be corrected with

myoflange

119

high myopia frequently results in

high riding lenses

120

causes of a rigid lens to displace frequently and pop out without cause

excessive posterior curve, flat base curve relationship

121

sorbic acid

low incidence of ocular sensitivity with soft contact lenses

122

soft lens edge lift can be corrected with

a steeper base curve

123

back toric soft lenses work best with

high corneal toricity

124

the cause of corneal edema observed inferiorly under prism ballast toric soft lenses

prism thickness

125

evaluating soft lens fit with either keratometry mires or retinoscopic reflex, distortion immediately after blinking is caused by

flat fitting lens

126

non wetting RGP lens may cause

hazy vision, lens awareness, dryness, grittiness

127

causes of lens flexure may include

pressure exterted by upper lid, lens material, apical clearance, against the rule corneal toricity

128

FDA recommends that extended wear lenses be worn for a maximum of

7 days

129

therapeutic soft lenses should be fit with minimal movement in cases of

recurrent erosion

130

aphakic patient with K readings of 40.50@180/41.25@90, large palpebral fissures and flaccid lower lids is a good candidate for

lenticular myoflange

131

CPC of a rigid les was ordered 7.84 mm and received as 7.94 mm, this lens is ___ than ordered

0.50 flatter

132

when evaluating fluorescein patterns, a special filter must be used with

fluropolymers

133

normal fitting soft lens will have

3 point touch

134

lens fitted for keratoconus should

align the apex

135

a soft contact lens that's too loose can show

edge stand-off, bubble under lens edge

136

correction of a high riding minus lens can be done by

prism lens

137

advantages of a myoflange vs single cut high plus lens

reduced center thickness, increased optical zone, reduced weight

138

increase tear exchange on an RGP lens

reduce lens diameter, flatten peripheral curve, decrease optic zone

139

what preservative is a mercury based compound

thimerosal

140

polishing compound that shouldn't be used with gp lenses

silvo

141

correcting a RGP lens fitted too flat

enlarge optic zone

142

best choice of a diameter for a HVID of 12.5 mm

14.5 mm

143

excellent material for patient with keratoconus

silicone acrylate

144

prism ballast, truncation, double slab off, peri ballast

soft toric lens designs

145

what should not be done to increase movement of tight fitting RGP lens

enlarge optic zone

146

what should be done to increase movement of tight fitting RGP lens

decrease optical zone, sagittal vaulting and lens diameter

147

performance of soft toric lens depends upon

corneal topography, lid shape, lid positioning, lid tightness

148

high degree of with the rule astigmatism fitted with a rgp lens will show touch

on horizontal meridian

149

rigid lens showing no apical clearance

flat fit

150

rigid lens showing apical pooling

steep fit

151

rigid lens showing apical vaulting

steep fit

152

rigid lens showing band shaped area of touch on flattest meridian indicated

steep fit lens

153

general rule of thumb when choosing diameter of soft lens

2 mm larger than HVID

154

mires not focused on radiuscope when verifying a rigid lens

warped, back toric, bitoric

155

RSVP

redness, sensitive to light, visual changes, pain

156

SOAP

subjective exam, objective exam, assessment, plan

157

most common complications with soft lenses

dryness + surface deposits

158

correctly fit lens

center on corneal apex, optical zone goes over whole visual axis

159

proper lens movement should allow

tear exchange under the lens

160

how often new soft lens wearers be seen

1 week, 1 month, 3 months, 6 months from initial fitting, every 6-12 months after

161

how often extended wear lens wearers should be seen

within 2 hours of waking up, 3 days, 1 week, 1 month, 3 months

162

how often therapeutic lens wearers should be seen

24 hours, 72 hours

163

when to do a back surface toric

corneal astigmatism exceeds 3.00D

164

when to do a front surface toric

little to no corneal astigmatism, but has residual or lenticular astigmatism

165

when to do a bitoric lens

moderate to high corneal and lenticular astigmatism

166

blepharitis

inflammation of the margins of the eyelids

167

chemosis

severe edema of conjunctiva

168

how long before spectacle blur should clear

20 minutes after lenses removed

169

how much power does the eye generate

60.00D

170

average corneal curvature

42.00D-45.00D

171

vertexing 4.00D-5.75D changes how many diopters

0.25D

172

vertexing 6.00D-7.75D changes how many diopters

0.50D

173

vertexing 8.00D-9.75D changes how many diopters

0.75D

174

vertexing 10.00D changes how many diopters

1.00D

175

normal range of keratometer

36.00D-53.00D

176

warm colors on topographer indicate

steeper curve

177

cool colors on topographer indicate

flatter curve

178

fuch's dystrophy

small endothelial cells die, cornea fills with water and swells

179

corneal ulcer

loss of epithelium, symptoms: painful red eye, excessive tearing, swollen eyelids, blurry, photophobia

180

corneal infiltrate

symptoms of foreign body, redness, photophobia, tearing

181

corneal scarring

opacity in cornea after healing, caused by infections trauma, surgery

182

bacterial keratitis

caused by contact use, eye injury, symptoms: sudden pain, redness, reduced vision, tearing, eye discharge, photophobia

183

aqueous humor replenished how often

90 minutes

184

rods

night vision

185

cones

color

186

bullous keratopathy

symptoms of light sensitivity, blurry vision, foreign body sensation

187

longer radius of curvature indicates

flatter lens

188

shorter radius of curvature indicates

steep lens

189

increasing the base curve will

flatten a lens

190

decreasing the base curve will

steepen a lens

191

decreasing sagittal depth will

flatten a lens

192

increasing sagittal depth will

steepen a lens

193

decreasing diameter will

flatten a lens

194

increasing diameter will

steepen a lens

195

how to steepen a lens

increase: diameter, sagittal depth decrease: base curve, radius

196

how to flatten a lens

increase: base curve, radius decrease: diameter, sagittal depth

197

corneal alignment/lid attachment

center superiorly to the cornea, move with lids, flat, no excessive pooling + even fluorescein

198

apical clearance/intrapalpebral

steep, sit directly on cornea, central pooling of fluorescein