ABO TEST Flashcards
0
Q
The fibrous tunic is comprised of the:
A
sclera and cornea
1
Q
The extra-ocular muscles are inserted into the sclera and serve to rotate the eye in all possible directions. There are of these muscles.
A
six
2
Q
Fusion occurs:
A
in the brain
3
Q
The aqueous fluid is continually being manufactured by:
A
the ciliary body
4
Q
The ability of the eye to bring objects of varying distances to focus on the retina is known as:
A
accommodation
5
Q
When accommodation is at rest, rays of light from a distant source come to focus in front ofthe retina. This condition is known as:
A
myopia
6
Q
When accommodation is at rest, rays of light from a distant source come to focus behind the retina. This condition is known as:
A
hyperopia
7
Q
Impulses are carried from the retina to the brain along the:
A
optic nerve
8
Q
That area ofthe retina capable of perceiving the greatest amount of detail is:
A
fovea centralis
9
Q
The average cornea has a refractive power of approximately:
A
43 diopters
10
Q
That layer ofthe cornea which is highly regenerative is:
A
the epithelium
11
Q
Night vision is chiefly a function of the:
A
rods
12
Q
A tendency of the visual axis to deviate inward while the eyes are in a position of rest is known as:
A
esophoria
13
Q
A “farsighted” eye is one that is:
A
hyperopic
14
Q
The term used to indicate “double visio
A
diplopia
15
Q
The condition in which the ability to accommodate for near vision becomes inadequate because of loss of elasticity of the crystalline lens is called:
A
presbyopia
16
Q
When there is a loss of vision without any apparent disease ofthe eye it is known as:
A
amblyopia
17
Q
A refractive error in which the rays of light do not come to a single point of focus is called:
A
astigmatism
18
Q
The condition in which the crystalline lens of the eye gradually loses its transparancy with consequent loss of visual acuity is known as:
A
cataract
19
Q
An ocular disease having as its primary characteristic a sustained increase in intraocular pressure.
A
glaucoma
20
Q
The space between the cornea and iris that is filled with aqueous fluid
A
anterior chamber
21
Q
A tendency of one eye to deviate upward is:
A
hyperphoria
22
Q
The photosensitive receptors of the retina which are responsible for sharp visual acuity and color perception are the:
A
cones
23
Q
The layer ofthe cornea which comprises ninety percent of its thickness is:
A
the stroma
24
A condition in which the refractive error of one eye significantly differs from that of the other and where both eyes have the same sign (i.e. both eyes are myopic or hyperopic) is known as:
anisometropia
25
The refractive error which results in two points of focus falling behind the retina is:
compound hyperopic astigmatism
26
The refractive condition caused by a damaged cornea so that rays of light come to many focal points on the retina is known as:
irregular astigmatism
27
The transparent, colorless mass of soft, gelatinous material which fills the eyeball behind the lens is the:
vitreous humor
28
The index of refraction of the crystalline lens is:
1.42
29
The cornea has an index of refraction of:
1.37
30
The index of refraction is lowest in:
air
31
When parallel rays of light Penter a prism, the light is deviated:
toward the base
32
One meter is equal to:
39.37 inches
33
Two meters equal centimeters.
200
34
The index of refraction of any given transparent material can be determined by:
dividing the speed of light in air by the speed of light in the material
35
The speed of light in air is approximately:
186,000 miles per second
36
When the direction of light is deviated in the course of passing from one transparent medium to another it is known as
refraction
37
Light travels through a certain transparent medium at the rate of approximately 109,412 miles per second. The index of refraction of that medium is:
1.70
38
The theory describes light as traveling through space in minute bursts of energy.
corpuscular
39
The focal length of a+ 1.00 diopter lens is:
+ 100 cm
40
If a converging lens has a focal length of +2 meters, its power is:
+ 0.50 diopters
41
The range of wavelengths which are perceived as visible light can vary with the individual, it is generally understood to lie between:
390 and 750 nanometers
42
If a prism can displace an image one centimeter at a distance of one meter, it is said to have a power of:
1 prism diopter
43
The distance between the crests of two waves is called the:
wavelength
44
The focal length of a - 5. 00 diopter lens is:
- 20 cm
45
Decentering a plus lens upward will result in:
base up prism
46
Prentice's Rule states that the amount of induced prism is equal to:
power of the lens times the decentration in millimeters + 10 Question 18
47
Prentice's Rule states that the amount of induced prism is equal to:
power of the lens times the decentration in millimeters +10
48
Rx : - 2.00 D OU with a PD of 63 mm. centers set 66 mm apart. How much total prism was induced and in which direction is the base?
0.6 prism diopters base in
49
Rx: = + 4.00 sph OU with a PD of 59 mm. During final inspection it was determined that the optical centers were positioned 4 mm too wide. How much prism was induced in each eye and in which direction is the base?
0.8 prism diopters base out
50
A diverging lens produces a ___ image.
virtual
51
Rays emanating from a point source of light are said to be:
diverging
52
To determine the power of a thin lens in air, it is necessary to consider:
front curve, back curve and index of refraction
53
A standard lens measure is calibrated for an index of refraction of
1.530
54
A+ 1.75 diopter lens fabricated with a +6.00 base curve will require a back curve of:
- 4.25
55
Toric transposition is used to determine:
lens power in the principal meridians
56
A patient presents you with an Rx + 2.75- 1.00 x 180 OU. The refractive anomaly indicated by this Rx is:
compound hyperopic astigmatism
57
Corrected curve lenses are designed to:
increase the useful area of the lens
58
The following lenses are all made with the same radius of curvature on the front surface. Which of these materials will yield the greatest front surface power?
flint glass
59
Question 8 8. Rx: OD + 2.50-0.50 x 180 OS +2.50 sph PD = 67. Final inspection found the optical centers 63 mm apart. How much total prism will this produce, and in which direction is the base?
1.0 prism diopters base in
60
If the Rx -3.00 + 0.50 x 90 is decentered 2mm too much, how much prism will be created, and in which direction is the base?
0.50 prism diopters base out
61
R x: +2.00- 4.00 X 45 How much prism will be created if the optical center of this lens is received 5 mm too wide?
none
62
As a corrected curve lens increases in minus power, the base curve tends to become gradually:
flatter
63
As the radius of curvature of a spherical surface increases in length, its curve becomes gradually:
flatter
64
As a corrected curve lens increases in plus power, the base curve tends to become gradually
steeper
65
As the radius of curvature of a spherical surface decreases in length, its curve becomes gradually:
steeper
66
Rx: Plano- 2.00 x 180. Which of the following refractive conditions is this lens designed to correct?
simple myopic astigmatism
67
If a patient is having difficulty handling their new soft, disposable contact lenses, what can a fitter do to make practice and learning easier?
Change to a lower water contact lens for the initial training
68
Which of these traits is not a benefit of hydrogel lenses?
Less surface deposits
69
Silicone hydrogel lenses have been approved by the FDA for up to 30 days of wear. This is considered __________.
Continuous wear
70
What type of allergic reactions are associated with the use of silicone hydrogel lenses?
Red and itchy eyes
Discomfort
Dryness
A patient can experience any of the above symptoms with silicone hydrogel lenses
71
Which of the following will not affect the safe handling of contact lenses?
Room humidifiers
72
What will help to relieve a temporary dry feeling when wearing contact lenses?
Frequent blinking
Remove the lenses and soak them
Use of physician approved eye
Any of the above can be effective
73
Tear exchange in a gas permeable lens is critical to an eye receiving adequate oxygen. Which procedure will increase tear exchange in a GP lens?
Decrease the optic zone
74
What is the definition of the edge apex?
The junction between the anterior and posterior zones
75
What is not correct regarding the cornea?
It is larger vertically than horizontally
76
All human tissues need replenishment of nutrition. How does the cornea receive nutrition?
From the tears, the aqueous and the limbal vessels
77
List the layers of the cornea from inside to out:
Endothelium, Descemet’s Membrane, Stroma, Bowman’s layer, epithelium
78
What is the Schirmer-2 test?
Is a test performed with special filter paper but no anesthetic
79
This systemic disease can cause large changes in refractive power when not controlled:
Diabetes
80
A significantly different refractive power between the right eye and the left eye is a condition is known as:
Anisometropia
81
Scleral contacts are ___________________________?
Designed to cover the cornea and approximately 1.00 mm of the sclera
82
What are the alternate names for the choroid?
Choroid coat and choroidea
83
What anatomical feature located in the posterior chamber produces aqueous humor?
The ciliary processes
84
How can contact lenses contribute to the development of keratitis?
Poor hygiene in the care of the lenses
Improper storage and use of cleaning solutions
Contact lenses being worn improperly
85
Cataracts and vitreous degeneration can cause _____________________?
Opacities of the media
86
When using a keratometer, the mires distort after a small amount of time. What does the contact lens fitter do?
Ask the patient to blink
87
After adding a supplemental +1.25 trial lens to a keratometer, you obtain a K reading of 52.00 @ 180/ 53.50 @ 90. What is the approximate corrected K reading?
61.00 @ 180 / 62.50 @ 90
88
A parallel fit of a contact lens can be referred to as:
Fitted on K
89
K reading on patient’s OD is 43.25 @180 / 44.00 @ 090. How much corneal astigmatism exists?
0.75 diopter
90
The K reading on a patient’s OS is 44.75 @ 180 over 44.75 @ 90. What is his ocular condition according to this reading?
His left eye is myopic
91
Which patient will most likely find reading more difficult when using contact lenses?
The myopic patient over 30 years of age
92
Most patients with Irregular astigmatism experience vastly improved vision with the use of a rigid contact lens. Why is this?
A rigid lens can create a lacrimal lens
93
Sometimes a lens prescription needs to be transposed from one form to the other. Which of the following is not a step involved in transposition?
Change the axis to 90◦
94
What is an ideal pattern with a well fitted spherical rigid contact lens?
The fluorescein dye shows a balanced distribution
95
A corneal stain is usually an indication of corneal insult. What type of stain indicates that the junctures of the posterior curve of a lens are faulty?
Arcuate staining
96
Which device projects a bigger picture of a rigid contact lens in order to inspect if for gross imperfections?
Shadowgraph
Projector magnifier
Projector inspection device
97
When using a profile analyzer, what pattern would indicate a good, smooth profile?
A ski shape
98
Which statement is not correct regarding the lipid layer of the tear film?
It is the inner most layer of the tear
99
What is the average blink rate?
Approximately every five seconds
100
Complete this sentence: Any tear deficiency _______________________________
Is a clear contraindication to extended wear lens use
101
What is the anatomical feature that forms the junction between the bulbar and palpebral conjunctivas?
The fornix
102
Name the four layers of the eyelid
The skin, the Orbicularis Oculi, the orbital septum and the palpebral conjunctiva
103
Bright light sends signals to the oculomotor nerve and these signals terminate on the iris sphincter muscle. These signals will __________________________________
Contract the iris muscle and reduce the size of the pupil **
104
Which of these is not a problem or disease of the eyelid?
Fissure
105
Eyelashes perform important functions. What are they?
They protect the eye from dust and debris and also signal danger
106
How many corneal dystrophies affect all parts of the cornea?
Over twenty corneal dystrophies
107
Ulcerative keratitis is a serious threat to vision. Which contact lens style is most associated with this damage?
Extended wear lenses
108
The endothelium can undergo harmful changes. What is the term for a change in cell shape variation?
Polymorphism
109
What ophthalmic device is used to perform a break-up time test (BUT) ?
Biomicroscope
110
Many angles can be created with the slit lamp. Which angle is used for a sclerotic scatter view?
90 degress
111
What is the smallest direct beam used with the slit lamp at approximately 1.00 mm?
Optic section
112
What is not easily revealed by using retro-illumination with a biomicroscope?
Gross edema
113
Which filters are commonly used when examining the eye with the slit lamp?
Wratten #12
Blue cobalt
Green
114
This type of stain occurs due to bubbles beneath the lens:
Dimple veil
115
What are some characteristics to consideration
| when choosing materials needed in order for the fitter to best advise the patient.
```
Percentage of water content
The oxygen permeability
How well the material defends against deposits
Thickness
Lens edge
Lens color/tint
Design parameters
Length of wear
Replacement intervals
```
116
A lens with greater hydration has the benefits of:
soft and flexible (pliable), often making the lens more comfortable.
117
What are some drawbacks for high water content contact lens ?
Too pliable for some patients
High water content may mean more surface deposits
shorter life.
118
What are some perks in regard to low water content in comparison to high water content ?
Less Pliable, low water content will feel more rigid when handled
less likely to have deposits on the surface
119
Soft contacts are manufactured from:
hydrogel material
120
High water content may have a negative affect on wearer, what are those negative affects:
Fluctuation in vision
dryness
changes in lens parameters
Surface Deposites
121
General benefits of soft contact lenses:
Comfort
Shorter adjustment period
Good alternative to eyewear for patient with minor corrections
Sports: excellent for athletics because soft lenses will not fall out of the eye
More comfortable in environments where conditions may cause a rigid lens to have particles logged underneath the lens
122
Silicone hydrogel contact lenses are advanced soft lenses that:________
more oxygen to pass through the lens to the cornea than regular soft ("hydrogel") contacts
123
Benefits of silicone hydrogel lenses
Extended wear
Continuous wear
Increased comfort and performance
Care of extended wear lenses
124
Silicone hydrogel lenses have been approved for wear at all times for up ______Days. These are FDA standards.
30
After 30 days, the extended wear lenses need to be taken out, properly cleaned and disinfected, and kept out of the eyes a minimum of one night. If they are disposables, they should be thrown away.
125
What are most common allergic responses to silicone hydrogel lenses ?
The most common complaints are:
redness
discomfort
itchy eyes
greater lens awareness
dryness symptoms
126
Even though Silicone Hydrogel lenses allow more oxygen to reach the surface of the eye, the added can ________ surface Wettability
Reduce
potentially making it harder for them to stay moist on the eye
127
People with marginal dry eyes would not benefit from a __________ contact lens
Silicone Hydrogel Contact lens
Because of reduced wetting angle
128
What kind of contact lens is a contraindication for people with Irregular Astigmatism ?
Soft Contact
Although fit and comfort may be good, satisfactory visual acuity may not be achieved due to an irregular corneal surface.
They need the tear film lens that RGP can offer.
129
What kind of contact lenses would not be good if there is liquid or gas in the air ?
Soft contact Lens
the lenses will absorb them and become tainted. Some chemicals can get so built up on the lens that the lens actually turns into something toxic, with the potential to really hurt the eye.
Because of their nature, soft lenses can absorb things like chemicals, germs, oils, and other materials.
130
Giant papillary conjunctivitis (GPC) is a type of conjunctivitis that is caused by wearing _____ soft contacts.
dirty
If a patient develops this one time, then that patient is more likely to develop it again, like an allergy.
Using disposable soft contacts sometimes help, but if the problem repeats itself, then the patient should be considered for a re-fit with rigid lens.
131
Things you should not handle when dealing with soft contact lenses ?
Spicy Food
Lotions, cosmetic sprays and creams
Handling of spicy foods can transfer on to the patient’s contact lenses even after the washing of hands. This can cause stinging and burning.
Lotions often contain conditioner which is harder to wash of the hands. Cosmetics, sprays, and creams can be difficult to remove from fingers. If a soft lens is affected, it may need to be discarded,
132
Patients who have irregularities or bumps on the sclera and/or bulbar conjunctiva may_____be able to wear soft lenses.
Not
If a bump is situated so that it moves the lens away from the eye, then the lens won’t receive enough hydration. Also, if the lens touches the bump during a blink, some irritation might occur. One solution could be to use a lens with smaller diameter.
133
What can be done to a GP lens to increase tear exchange ?
Reduce the overall lens diameter
Flatten the peripheral curves
Decrease the optic zone
Basically loosening the lens
134
Optical Zone
is the chord diameter over which the base curve extends on the posterior surface of the contact lens
135
How much flatter is the peripheral curve in comparison to the base curve?
0.70 mm to 1.50 mm flatter than the base curve radius
136
What is blending in regard to contact lenses ?
Blending is the treatment given to the sharp junctions created by the differences in the radii of curvature between the base curve, the secondary curve, and the peripheral curve.
137
What two curves on the posterior aspect of a contact lenses are more likely to be blended ?
Secondary curve and the peripheral curve.
A blend is rarely required at the base curve/secondary curve junction. This is due to minimal change between the two radii.
138
What are other names for the anterior optical zone radius
the power curve or the lenticular cap
139
What is the Lens Edge designed for ?
The edge is designed to limit adverse lid irritation during blinking, and plays a role in keeping the posterior lens surface away from the cornea.
140
The edge of a lens can be divided into 3 zones that are they ?
Anterior Zone
Posterior Zone
Edge Apex
The Anterior Zone is that portion of the edge in contact with the upper lid during the blink cycle. Its function is to minimize lid irritation during the blink.
The Posterior Zone is a small reverse curve placed on the posterior lens surface to flare the edge away for the cornea. Its function is to allow free movement of the lens across the cornea during the eye excursions and to permit lens removal using scissor blink technique. The posterior zone also allows the lens to be safely centered on the cornea when lens dislocation occurs.
The Edge Apex is the junction between the anterior and posterior zones. This junction must be well rounded to minimize lid awareness during the blink.
141
Cornea
The cornea is the clear surface on the front of the eye that covers the iris and pupil. It lets light into the eye.
142
What is the radius of curvature of the anterior surface of the cornea ?
7.7 mm
143
What is the radius of curvature of back surface of the cornea ?
6.8 mm
144
The center of thickness of the cornea is ?
.5mm
145
The is the edge thickness of the cornea ?
1.0 mm
146
What is the average diameter of the cornea horizontally ?
11.5 mm
147
What is the average diameter of the cornea
| vertically ?
11.2 mm
148
What is the average dioptric power of the cornea ?
43.00 D or 70% of the total amount of refraction.
149
What is the most powerful refractive surface of the eye ?
Cornea
150
what is the anterior surface refractive power and the posterior surface power ?
Anterior: +48.8 D
Posterior: -5.8 D
151
The longer the radius of curvature the _______ the lens
Flatter or looser the lens
152
The shorter the radius of curvature the __________ the lens
The steeper or tighter the lens
153
What is the corneal cap ?
is the central portion of the cornea with a constant radius of curvature AKA apical zone of the cornea
154
Apical mean what ?
Apex or at the top
155
What is the index of refraction of the cornea ?
1.376
156
The cornea can receive nutrients from that ?
oxygen by the aqueous humor
tears
vascular blood vessels in the limbus.
157
Where does the anterior aspect of the cornea get is oxygen from ?
Air diffused by tears
158
Where does the posterior aspect of the cornea get its oxygen from ?
Aqueous Humor
159
When there is not enough oxygen in the eye this is called ?
Hypoxia
160
Epithelium makes up ____ % of the corneal thickness
10 %
161
Cornea epithelial cells can In the first 24 hours they cells slide and migrate to cover any open area, then the epithelium will begin to generate new cells over the damaged area.
True or false ?
True
162
Stroma comprises who much of the cornea ?
90%
163
The stroma has ______ kind of of collagen fibers that are woven together at right angles.
Lamellae
164
Endothelium is made up of what kinds of cells ?
one layer of hexagon-shaped cells; it makes up 10% of the thickness of the cornea.
165
How long is a BUT (Break Up Time)
10-12 seconds
166
What is a schemer's Test for ?
evaluates aqueous tear production
It is used in the assessment of patients with signs and/or symptoms of dry eye. It can determine whether surface dryness is due to reduced tear production from the lacrimal glands as opposed to some other cause, such as blepharitis, meibomitis, or exposure.
167
How do you perform a Schirmer's test ?
a special filter paper is used which is 5mm wide and 35mm long in an eye that has not been anaesthetized. A normal tear output should wet at least 15 mm of filter paper in 5 minutes.
168
What is the difference between Schirmer 1 and Schemer 2 test ?
Shirmer 1 test Has anesthetic and Shirmer 2 test does not have any anesthetic ( measures baseline plus reflex secretion)
169
What is a nevus
a benign growth; shape is small and flat, color is pigmented (tan, brown, or skin color)
170
Pinguecula
benign growth; shape is small, roundish, color is yellowish or yellowish brown.
171
Pterygium:
an abnormal growth on the medial bulbar conjunctiva; shape is triangular; possibly caused from irritation from the sun. This condition may cause scarring in the cornea and eventually may cause vision impairment or vision loss.
172
Subconjunctival hemorrhage:
this is when a blood vessel breaks under the conjunctiva; symptoms include a bright red eye that usually lasts a week to ten days and does not actually harm the eye. This can be caused by trauma, sneezing, coughing, high blood pressure, or other causes.
173
Fornix
is between the lid and the globe, and you can see it on yourself if you pull down your bottom eyelid.
174
The crystalline lens is ___ mm across and 3.5 mm thick
10mm across and 3.5 mm thick
175
What is the total power of the eye is _____ diopters.
60 Diopters
Cornea supplies about 70% of that power and most of the remaining power is supplied by the crystalline lens.
176
That is the Amplitude of Accommodation
the maximum amount that the eye’s crystalline lens can accommodate (change shape), in diopters (D).
177
presbyopia is
A loss of the flexibility in focus is inevitable as we get older due to stiffening of the lens
178
senile cataract
The most common type of cataract is caused by the aging of the crystalline lens
179
Factors that cause cataracts
heredity
injury
disease
toxicity
radiation.
180
What is Aniridia ?
is a partial or complete loss of the iris. This is a congenital disorder.
181
What is Ocular albinism
where there is no pigment in the iris or retina.
182
What is Bullous Keratopathy
is damage or disease in the endothelial region which results in bullae (swollen) appearing. The patient may experience sharp pain, light sensitivity, and a feeling of tearing or having foreign matter in the eyes.
183
What is a keratometer for ?
also called the ophthalmometer, measures the curve of the cornea.
184
What is Transient keratometric
mire distortion can be caused by pre-ocular tear film, and can be cleared up by asking the patient to blink.
185
What is refraction ?
As light comes into different mediums, the speed slows downs and bends.
186
How much prismatic effect is there with contract lenses ?
None
The lenses are right on the eye, so the optical center is always directly in front of the visual axis.
187
Will accommodation be easier or harder for a hyperopic person ?
a person with hyperopia will have an easier time accommodating to close range vision than with glasses. They will have less accommodating to do.
188
Will accommodation be easier or harder for a myopic person ?
a person with myopia will need to accommodate more with their contact lenses then with their eyeglasses.
f a person is over 30 and is also a strong myope, they might find it hard to read with contact lenses. That is because contacts in a strong myope create a need for more accommodation at the reading level. Reading glasses might become necessary along with the contacts.
189
What two kinds of hyperopia are there ?
```
Axial hyperopia (length of eye is too small)
refractive hyperopia (crystalline power is too weak)
```
190
Contraindications for bandage lenses
Very dry eyes
Bad hygiene
infections are also contraindications to bandage lenses.
191
What is 3 and 9 o'clock staining ?
seen on a patient with a rigid lens due to lack of hydration or exposure, can happen if the patient does not blink often enough,if the person is wearing the lenses too long at a time, if the edges are too thick
192
What is Arcuate Staining ?
shaped like an arch on the edge of the lens and It happens because the blend between the junctures of the posterior curves is inferior.
193
What tools can be used to evaluate the overall diameter ?
diameter gauges,
| measuring magnifiers, or projection magnifiers
194
What tools can be used to evaluate the Posterior Optical Zone Diameter?
measuring magnifiers or shadowgraphs
195
What tools can be used to see the Peripheral Curves:
measuring magnifiers or shadowgraphs
196
What tools can be used to see Blends ?
profile analyzers or fluorescent light bulbs
197
what tools can be used to see Center and Edge Thickness:
thickness gauges
198
what can be used for Checking Edges:
hand-held magnifier, measuring magnifier, shadowgraphs or slit lamps (be sure to include the profile, shape and apex)
199
What are the 3 layers of the cornea ?
lipid layer
aqueous layer
mucoid layer
200
Where do the oils that make up the lipid layer come from ?
It consists of oils that come from the meibomian and Zeis glands
201
What is the main function of the lipid layer ?
It functions primarily to prevent rapid evaporation which would result in dry areas on the cornea and subsequent discomfort and corneal damage.
202
What is the index of refraction of tears ?
1.3375
203
How long is a BUT test ?
10-12 seconds .
A BUT of less than 10 seconds may contraindicate contact lens wear.
204
What is dacryoadenitis
Inflammation of the lacrimal glands
205
what is dacryosystitis
an inflamed lacrimal sac
206
what is epiphora
blocked drainage system, causing tears to drain down the face
207
what is keratitis sicca
tear deficiency, causing dry eyes and an inflamed cornea
208
The conjunctiva is typically divided into three parts what are they ?
Palpebral or tarsal conjunctiva - lines the eyelids. It is tight over the tarsal region and less tight over the orbital region
Bulbar or ocular conjunctiva - Covers the eyeball, over the anterior sclera. It is the part that lines from the globe to the limbus, and it is tight in that area
Fornix conjunctiva - Forms the junction between the bulbar and palpebral conjunctivas. It is loose and flexible, allowing the free movement of the lids and eyeball
209
What are the horizontal and vertical measurements of the palpebral fissure
Vertical: 10mm high.
Horizontal: 30mm across
210
What is Blepharoptosis ?
(ptosis): this is when the upper eyelid is droopy
211
What is a Chalazion ?
this is when the meibomian gland in the eyelid becomes inflamed and blocked, creating a bump on the lid.
212
What is a Hordeolum
(stye) this is a swollen bump that is usually on the base of the eyelashes; an infection on a Zeis gland; common in babies
Bacteria related
213
What is the Tolerance of a Contact Lens CPC or Base?
+/- .025mm or .12D
214
What device do you use to inspect the base curve of CPC of a contact lens ?
Radiuscope
215
What is the Tolerance of contact Lens Power ?
+/- .12D if it is less then 10 D
| +/- .25D if it is more then 10D
216
How do you check Contact lens power ?
Lensometer
217
What is the tolerance of the Center of Thickness of a Contact Lens ?
+/- .02mm
218
How do you check the thickness of a contact lens ?
Dial Gauge (aka) Thickness gauge
219
How do you check the total diameter of a contact lens ?
Measuring Magnifier
Projector Magnifier
V channel
Slip or Slot Gauge
220
What is the tolerance for Total Diameter of a contact lens ?
+/- .05mm
221
If a soft Contact Lens Rx has less then 1.00D of Cyl what kind of lens can be fit ?
Sphere
222
If a soft contact Lens Rx has more then 1.00D of Cly what kind of lens can be fit ?
Toric Lens
223
When do you use a front surface toric design on a RGP Lens ?
When there is more then 1.00D of residual/Lenticular (difference in corneal and rx astigm) in the Rx. This makes an optical problem?
224
When do you use a back surface toric or bitoric design on a RGP Lens ?
When the corneal astigmatism is more then 3.00 D ( fitting Problem)
225
When do you do vertex compensation for a contact lens ?
-/+ 4.00D sphere power
226
When do you use a toric design for a soft contact ?
When the cylinder is more then 1.00D or when the sphere is 3 x more then the cyl.
