NCLE Flashcards
(143 cards)
1
Q
synonymous w/ astigmatism
A
Toric
2
Q
synonymous w/ presbyopia/c
A
multifocal
3
Q
combination of GP lens center w/ soft lens outer skirt
A
hybrid cl
4
Q
most frequently prescribed
material containing varying amounts of water
comfort is immediate
A
hydrogel contact lens
5
Q
soft contact lens
delivers greater oxygen w/o increasing water content( oxygen is more soluble in silicone rubber than water)
A
silicone hydrogel cl
6
Q
daily
overnight/continuous
flexible
A
soft cl wear schedule
7
Q
smaller, firmer, durable
A
gas permeable lens
8
Q
recommended for Pts w/ irregular corneas
excellent for Rxs w/ reading add
A
gp contact lens
9
Q
nonsurgical way to eliminate/reduce need for eyeglasses or contact lens wear during the day
A
orthokeratology
10
Q
device/appliance worn overnight to gently reshape the surface of the eye after contact lens are removed
provides clear, unaided vision that can last all waking hours
this is removed in the morning
A
retainer lens
11
Q
provides sharp visual acuity of GP lens w/ the comfort and wearability of soft contact lens
A
hybrid cl
12
Q
provide nutrients and oxygen to cornea
A
tears
13
Q
average central cornea curvature
A
7.8mm
14
Q
cornea index of refraction
A
1.37
15
Q
cornea power
A
43.25D
16
Q
aspheric, gradually flattens from center to edge
A
cornea surface
17
Q
steepest point of Cornea
may be found in center of cornea
A
corneal apex
18
Q
has the least amount of curvature
“with the rule” astigmatism
A
180 meridian
19
Q
has the steepest curvature
“against the rule” astigmatism
A
90 meridian
20
Q
for irregular astigmatism
rigid lens surface replaces irregular corneal surface
allows light to be bent so it falls more clearly on retina
A
rigid gp lens
21
Q
~10.6mm
A
cornea vertical diameter
22
Q
~11.7mm
A
cornea horizontal diameter
23
Q
center: .5mm-.6mm
periphery: 1.00mm
A
cornea thickness
24
Q
epithelium
bowman’s membrane
stroma
descemet’s membrane
endothelium
A
layers of cornea
25
5-6 cells thick
regenerates 3-7 days
regulates flow of water and nutrients into other layers
assists in removing waste from lower layers
epithelium
26
below epithelium
very resilient
once damaged it CANNOT regenerate
bowman’s membrane
27
~90% of cornea’s thickness
formation of dense collagen fibers is responsible for maintaining cornea’s transparency and shape
stroma
28
collagen fiber layers in stroma separate due to excess fluid
results in loss of transparency
corneal edema
29
between stroma and endothelium
like bowman’s in that once damaged it cannot regenerate
descemet’s membrane
30
400,000 - 500,000 cells in a single layer
controls water content of stroma
keeps cornea clear
cells do not regenerate or reproduce
endothelium
31
when endothelium cells change from hexagonal shape to fill in gaps left from lost endothelium cells
pleomorphism
32
endothelium cells change size(expand)
to fill in gaps from lost endothelium cells
polymegathism
33
central posterior or back surface of a lens
base curve
34
longer radius
lower diopter
flatter curve
35
shorter curve
higher diopter
steeper curve
36
oblique like shape
expressed by E value
aspheric curve
37
E value = 0
spherical
38
E value = 0-1
elliptical
39
E value = 1
parabolic
40
E value > 1
hyperbolic
41
decrease diameter
flatten BC
compound loose fit
42
increase diameter
steepen BC
compound tight fit
43
central area of contact lens containing refractive power
needs to be positioned over pupil to provide optimal vision
optic zone
44
flatter
better help align the cornea
intermediate curves
45
outer curves allow for tear flow underneath contact lens
peripheral curves
46
lens thicker at bottom making it heavy
helps prevent rotation while worn
most often used in tori’s and bifocal lens
ballasted lens
47
lens w/ a flat edge
helps position lens on the lower lid
used in some rigid topic and bifocal
trunction lens
48
rigid lens with a single or multiple holes allowing oxygen and/or tear flow
fenestration lens
49
human blinks this many times per minute
7-12
50
tarsal glands located inner edge of eyelid margins
sebaceous/oil secrete lipids into tear film
meibomian glands
51
1. oil/lipid
2. aqueous/lacrimal
3. mucin
tear film layers
52
helps prevent evaporation of tear film
helps prevent tears from flowing onto face
oil/lipid tear film
53
largest volume
secreted by lacrimal gland
mostly water w/ oxygen and nutrients to sustain corneal health
provides moisture to surface of eye
aqueous/lacrimal tear film
54
innermost, hydrophilic layer closest to corneal surface
secreted by conjunctival globlet cells helps anchor tear film to surface of eye
mucin tear film
55
1. creates smooth surface for light to enter eye
2. removes foreign bodies, epithelial cells, and mucus from surface of eye
3. provides lubrication for blinking
tear film functions
56
~7
range from 6.7 - 7.6
pH of tear
57
condition where there is a chronic lack of lubrication and moisture in eye
dry eye
58
more prevalent in women
becomes more common as individuals age
dry eye
59
Pts who:
wear lenses part time
are exposed to dusty environments
engage in certain contact sports
GP lens are not suitable for
60
interpalpebral
keeps lens in a central position
minimizes "interactions" w/ eyelids
(keeps edges thin and tapered)
apical clearance
61
lens positioned slightly high on cornea
keeps upper lens edge tucked under upper eyelid
when wearer blinks lens moves as it were "attached" to upper eyelid (movement provides good tear exchange [comfort is improved])
apical alignment
62
these have larger diameter and flatter BC
apical alignment
63
lens diameter generally should be smaller than visible iris diameter by
2.3mm
64
11mm
small iris size
65
11.5mm
medium iris size
66
12mm
large iris size
67
flatter cornea
larger optical zone
68
steeper cornea
smaller optical zone
69
GP lens has steeper and steeper curves in secondary
reverse curve design
70
12.25mm
.3-.4mm widths
typical peripheral curve radius
71
fitting flatter than K creates
minus tear lens
72
fitting steeper than K creates
plus tear lens
73
adding plastic to front surface of lens edge
lenticulation
74
necessary to all + lenses and lenses that are less than -2.5D
lenticulation
75
removing excess material on a higher minus Rx for comfort
hyperflange
76
astigmatism 0D - 1.50D = .5D flatter than K
astigmatism 1.75D - 2.50D = on flat K
astigmatism >2.50D = use toric design
apical alignment fit
77
astigmatism 0D - .50D = on flat K
astigmatism .75D - 1.25D = .25D steeper than K
astigmatism 1.50D - 2D = .50D steeper than K
astigmatism 2.25D - 2.75D = .75D steeper than K
astigmatism 3D -3.5D = 1D steeper than K
apical clearance fit
78
GP lenses larger than Corneal GP lenses
rests either on limbral area or scleral area
scleral lens
79
8.7mm - 10mm diameter
corneal GP lens
80
13mm - 15mm
rest near limbus or where cornea and scleral meet
aka semi-scleral
corneo-scleral GP lens
81
15mm - 18mm
covers entire corneal surface
rests on sclera
mini scleral GP lens
82
18mm - 24mm
provides greatest amount of clearance between back surface of lens and front surface of cornea
true scleral GP lens
83
material's ability to keep its shape
modulus of elasticity
84
are less resistant to stress
low modulus of elasticity
85
holds their shape better
high modulus of elasticity
86
material(s) that absorb <4% water by weight
hydrophobic
87
material(s) that absorb >4% water by weight
hydrophilic
88
have negative charge
tend to attract more deposits
ionic material
89
low water non- ionic
group 1 FDA class
90
high water, non-ionic
group 2 FDA class
91
low water, ionic
group 3 FDA class
92
high water, ionic
group 4 FDA class
93
polymethylmethacryl
first rigid plastics
provided excellent optics
easy to manufacture
does not allow oxygen to pass through
rarely used
PMMA
94
first GP lens
improved ability for oxygen to pass through
poor wetting (uncomfortable)
silicone acrylate
95
flourine added to silicone acrylate lens
helped to be more wettable (improved comfort)
flourosilicone acrylate
96
the greater the water content the greater the oxygen permeability
however it causes the eye to dehydrate quicker
soft contact lens
97
need frequent replacement (due to being prone to deposits)
larger and more flimsy (harder to apply/remove)
cons of soft CL
98
used to measure a GP lens BC
aka spherometer
radiuscope
99
can be observed using a flourescent bulb
lens blend
100
a well blended lens will reflect a smooth line shaped like a
J
101
used if refractive astigmatism <.75D
spherical lens
102
used if refractive astigmatism >.75D
toric lens
103
good for Pts w/ against the rule astigmatism
soft toric lens
104
prism ballasting
dynamic stabilization
back surface toricity
soft toric lens stabilizers
105
extra thickness on interior(bottom lens)
prism ballast
106
double slab off
ideal for against-the-rule astigmatism
dynamic stabilization
107
aka biomicroscope
used to evaluate the eye and CL
slit lamp
108
used to highlight areas of disruption on Cornea
blue filter
109
used to evaluate CL to Cornea relationship when fitting GP lens
blue filter
110
helps highlight area of red
green filter
111
light and oculars are focused on same point in slit lamp
direct/focal illumination
112
used to observe corneal staining, opacities,deposits, and/or scratches on lenses
used w/ blue filters
direct/focal illuminations
113
used to take a general look at the eye
diffuse illumination
114
light is spread over a large area
diffuse illumination
115
used to evaluate position and movement of soft or GP CL
diffuse illumination
116
light is focused next to are being observed
indirect illumination
117
light is bounced off of iris so the object or condition on Cornea is lit from behind
retro illumination
118
subepithelial and diffuse edema are most easily observed by
retro illumination
119
2-3mm slit beam is directed 90 degreees to observer
light is scattered back and forth through cornea
sclerotic scatter
120
used to view areas where cornea lacks transparency
sclerotic scatter
121
most often used to locate corneal edema
sclerotic scatter
122
used when observing tear film under GP lens to determine fit
wratten filter
123
in a wratten filter this color means there is space between GP lens and cornea
bright green
124
in a wratten filter this color means there is a lack of space between GP lens and cornea
dull/dark green
125
lines inside of eyelid, soft, loose tissue
palpebral conjunctiva
126
soft, loose tissue extends from inside eyelid to cover sclera
bulbar conjunctiva
127
Tear Break Up Time (TBUT) in normal eye
10-12 seconds
128
two different k readings in axis
ie 43.00 k@180 / 45.00 k @ 90
corneal astigmatism
129
difference in astigmatism between spectacle RX and no difference in k readings
ie RX -3.00 -1.50 x 180
44.0k @ 180 / 44.0k @ 90
lenticular / remainder astigmatism
130
Individual w/ against the rule astigmatism
good for soft toric lens
131
Individuals w/ oblique astigmatism
good for soft toric lens
132
spherical GP lens only
correct corneal astigmatism
133
longer radius
flatter curve/lower diopter
134
shorter radius
steeper curve/higher diopter
135
higher Diopter
steeper curve
smaller radius
136
lower diopter
flatter curve
bigger radisu
137
Diameter is the same and flattening BC
decreases sagital depth
138
increase diameter and keeping BC the same
increases sagittal depth
139
thinner CL
higher Oxygen transmissibility
140
vertex lens at
+/- 4.00
141
when vertexing lens minus
will be less(higher +)
142
when vertexing lens plus
will be higher
143
steeper/smaller sagittal depth
tighter fit
