1
Q
What type of image does a negative lens produce when a real object is presented?
A
A virtual, upright, and smaller image
This holds true regardless of whether the object is placed in front of or behind the first focal point.
2
Q
What is the function of field-expanding lenses, such as Fresnel lenses?
A
To enhance the field of view in applications like rear windows of vans or RVs
Fresnel lenses are designed to reduce the amount of material required while maintaining optical performance.
3
Q
What type of image is produced when a real object is placed between the first focal point and a plus lens?
A
A virtual, upright, enlarged image
This principle is the basis for single lens magnifiers.
4
Q
What type of image does a plus lens produce when a real object is placed to the left of the first focal point?
A
A real, inverted image
This principle is foundational for imaging systems such as the eye, camera, and projector.
5
Q
Fill in the blank: A real object presented to a _______ lens will always produce a virtual, upright, and smaller image.
A
negative/minus
6
Q
Fill in the blank: The basis for single lens magnifiers is when a real object is placed between the first focal point and a _______ lens.
A
plus
7
Q
True or False: A plus lens will always produce an upright image regardless of the object’s position.
A
False
A plus lens can produce both real and virtual, upright or inverted images depending on the object’s position relative to the focal point.
Object between 1st focal point & lens = virtual, upright, magnified image
Object placed to the left of 1st focal point = real, inverted, magnified image
8
Q
What is the wavelength range of UV-A light?
A
315-380 nm
UV-A is the longest of the three types of UV light.
9
Q
How does UV-A radiation compare to other types of UV light in terms of damage?
A
Considered the least damaging
UV-A penetrates deeper into the skin.
10
Q
Which type of UV light is more abundant at the Earth’s surface?
A
UV-A radiation
UV-A is much more abundant than UV-B and UV-C.
11
Q
What is the wavelength range of UV-B light?
A
280-315 nm
Overexposure to UV-B can lead to sunburn.
12
Q
What health issues are associated with UV-B exposure?
A
Sunburn, skin cancer, cataract formation
UV-B has a higher correlation with these issues than UV-A.
13
Q
What is the wavelength range of UV-C light?
A
100-280 nm
UV-C has a shorter wavelength and is high-energy.
14
Q
Solar keratitis
A
condition can be caused by prolonged exposure to UV-C
- ”sun burn of the eye”
- aka photokeratitis or ultraviolet keratitis
- painful inflammation of the cornea caused by exposure to UV radiation from the sun
- The majority of UV-C light is absorbed by the ozone layer.
15
Q
Which part of the eye absorbs the majority of UV-C light?
A
The cornea
The cornea protects the eye from UV-C exposure.
16
Q
What absorbs the majority of UV-A and UV-B light in the eye?
A
The crystalline lens
This protects the retina from potential UV damage.
17
Q
What can occur over time to the lens of the eye as a result of UV exposure?
A
Formation of a cataract
The lens may become impaired over time.
18
Q
How much light is needed in order to trigger a single molecule of rhodopsin?
A
1 quanta of light (smallest amount of light possible)
19
Q
As the power of a condensing lens increases what happens to the FOV, magnification and working distance?
A
Increase in power = increase FOV, decrease in mag and decrease in working distance
Ex: 90 D vs 78 D lens
20
Q
Which astigmatic dial is fixed?
A
Clock dial
* Target is not mobile
21
Q
What is the most common complication of RGPs?
A
3-9 staining (peripheral corneal desiccation)
22
Q
What is the most common complication associated with rigid gas permeable contact lens wear?
A
Peripheral corneal desiccation, also known as 3-9 staining
23
Q
What symptoms do patients typically report with peripheral corneal desiccation?
A
Mild symptoms of interpalpebral redness and slight irritation
24
Q
What does a slit lamp examination reveal in cases of peripheral corneal desiccation?
A
Superficial punctate staining that can vary from small to larger coalescing areas of SPK, with deep fluorescein staining
25
What is dellen formation associated with in contact lens wear?
Deep fluorescein staining
26
What causes the signs of peripheral corneal desiccation?
Excessive edge lift of the contact lenses leading to tear film disruption
27
How can the signs and symptoms of peripheral corneal desiccation be minimized?
Adjustments to the fit of the contact lenses to decrease edge lift and increase lid apposition
28
What adjustments can be made to achieve better fit and minimize symptoms?
Steepening the base curve and/or steepening the peripheral curves of the contact lens
29
What additional modifications can help minimize peripheral corneal desiccation?
Thinning the contact lens edge and lenticulating higher minus lenses
30
Is changing the material of the lens beneficial in reducing corneal signs related to 3-9 staining?
No, studies have shown it has no benefit
31
True or False: 3-9 staining is purely fit related.
True
32
How to calculate JND?
Divide denominator by 100
Ex: 20/400
400/100 =4
With trial frame show +2.00 and -2.00 lenses
33
What is the ANSI standard tolerance for cylinder axis of prescriptions with a cylinder power of 1.75 diopters or greater?
2 degrees in any direction
## Footnote
This tolerance applies to prevent significant visual distortion.
34
What is the ANSI tolerance for sphere powers above 6.50 D?
+/- 2% of the power
## Footnote
This tolerance helps ensure adequate visual correction.
35
What is the ANSI standard for error tolerance in cylinder power for cylinder powers of 2.25 to 4.50 D?
+/- 0.15 D
## Footnote
This tolerance ensures that the cylinder power is accurate for effective vision correction.
36
What is the equivalent logMAR acuity of 20/60?
0.48
explanation: take reciprocal of decimal acuity
20/60 =0.333
Now take the log of the reciprocal
Log(1/0.333)=0.478
37
Make sure you know how to calculate!!
38
What is the process called when lenses are inserted into frames without using heat?
Cold snapping
## Footnote
This method is used for certain frame materials that do not require heat.
39
What is a major variant in the lens insertion process for plastic frames?
Whether or not heat is used
## Footnote
The amount of heat can also vary depending on the material.
40
What material requires high amounts of heat to insert lenses?
Optyl
## Footnote
Optyl can bend under its own weight when heated properly.
41
At what temperature can Optyl material be safely heated?
100-130 degrees Celsius
## Footnote
Heating beyond this range may damage the material.
42
Which materials utilize only minimal amounts of heat if lenses cannot be cold snapped?
* Cellulose acetate
* Cellulose proprionate
* Carbon fiber
## Footnote
These materials may allow for some heat but not extensive heating.
43
What should NOT be done to polycarbonate and polyamide materials during lens insertion?
They should not be heated at all
## Footnote
Heating these materials can lead to warpage.
44
What is required for edged lenses when using polycarbonate and polyamide materials?
They must be fabricated exactly to size
## Footnote
This is crucial to avoid issues during lens insertion.
45
True or False: All plastic frame materials require heat for lens insertion.
False
## Footnote
Some materials can use cold snapping, while others require heat.
46
True or false
BIO has a smaller magnification, larger field of view and an inverted real image
True
47
Direct ophthalmoscope features what kind of image?
Upright virtual image
48
What is chromatic aberration?
A type of distortion in which a lens is unable to focus all wavelengths of light on the same convergence point.
49
What causes chromatic aberration?
The variation of the refractive index of any medium with wavelength.
50
Which wavelengths bend more as they pass through a lens?
Shorter wavelengths (blues).
51
Which wavelengths bend less as they pass through a lens?
Longer wavelengths (reds).
52
What are the two types of chromatic aberration?
* Longitudinal chromatic aberration
* Lateral chromatic aberration
53
During subjective refraction, where should the retina be centered?
Between the image point for the shorter and longer wavelengths.
54
What test is used to balance the image points for different wavelengths?
The Red-Green test.
55
If a patient reports clearer letters on the red side of the Red-Green test, what does this indicate?
The center point is too far in front of the retina.
56
What is the recommended lens adjustment if the red side is clearer?
A minus lens will improve this balance (Red Add Minus-RAM).
57
If a patient reports sharper letters on the green side of the Red-Green test, what does this indicate?
The center point is too far behind the retina.
58
What is the recommended lens adjustment if the green side is sharper?
A plus lens will shift the balance (Green Add Plus-GAP).
59
The entire Red-Green test is dependent upon the principles of _______.
[chromatic aberration]
60
Which type of aberration is primarily responsible for results found using the Red-Green test when performing subjective refraction?
Chromatic aberration
61
4x
Explanation: entering acuity divided by goal acuity
400/100 = 4x magnification
62
True or false
When an object is located at half the focal length of the plus thin lens the object and image are the same size
FALSE
* when the object is located TWICE the focal length of the plus thin lens the object and image size are the same
63
The “reduced eye” consists of a single spherical refracting surface that separates air and aqueous. What is the radius of curvature of the surface?
+5.55 mm
* axial length of the reduced eye is 22.22 mm
64
Principal of univariance
Fact that once quatra are absorbed by rhodopsin, all of the information pertaining to the light (such as wavelength) is lost. Therefore if the photopigment rhodopsin is bleached, the wavelength does not matter because the final result will be equivalent
65
Purkinje shift
Shift in peak spectral sensitivities during the change from Scotopic to photopic vision. Means that as light increases, longer wavelengths appear brighter because the peak spectral sensitivity for Scotopic conditions is 507nm and 555nm for photopic vision.
66
Mesopic conditions
Both rods and cones function simultaneously, such as during twilight
67
Why is the retina referred to as being a duplex?
Because it possesses two separate groups of photoreceptors which function under different lighting conditions
68
While performing retinoscopy, how does the resultant reflex change as you approach neutral motion?
Reflex is wider/broader, brighter and appears to move more quickly
69
Question
70
Question
71
How is SWAP (short wavelength autoperimetry) performed?
Visual field instrument with a blue test target and a yellow background
* blue target ensures that S-cones respond maximally to stimulus against a yellow background
* yellow background enforces M and L cone suppression because wavelength will cause bleaching of photopigments
*S-cones may be more vulnerable to damage in earlier stages of glaucoma, therefore SWAP is used to monitor for early changes in visual field
72
A +3.00 D hyperope is corrected with +1.50D contact lens bilaterally. If he views a near object at 22cm, what degree of accommodation is required to achieve a clear retinal image (round to nearest 0.25D)
+6.00D
Accommodation required to view near object: 1/0.22m = +4.50
Hyperope is only half corrected, therefore still need +1.50 to be emmetropic, thus need +1.50 more accommodation + (+4.50) in order to have a clear retinal image
(+4.50) + (+1.50) = +6.00 D
73
True or false
For a wave of a given velocity, frequency and wavelength are inversely related
True
74
True or false
The speed of light is a universal constant that is independent of the observer or the source
True
C= 3.0 x 10^8 m/s or 300,000 km/s
75
Where are the far points located for a person with compound myopia?
Both are a finite distance in front of the eye
*far point will always be located in front of a myopic eye
76
Which characteristic indicates that an image is real?
Image is inverted
## Footnote
A real image is formed when light rays converge.
77
What vergence value indicates a real image?
Vergence is positive
## Footnote
Positive vergence indicates converging light rays.
78
Which characteristic indicates that an image is virtual?
Light rays are diverging
## Footnote
Diverging light rays result in a virtual image.
79
True or False: A real image is upright.
False
## Footnote
A real image is typically inverted.
80
Fill in the blank: If light rays are diverging, the image is _______.
upright
## Footnote
Diverging light rays create an upright image.
81
What does it mean if an image is focusable on a screen?
The image is considered a real image
## Footnote
Real images can be projected onto a screen.
82
Select the three characteristics that indicate the image is real.
* Image is inverted
* Vergence is positive
* Light rays are converging
## Footnote
These characteristics confirm the image is real.
83
What are lower order aberrations?
Can be corrected by glasses, contact lenses, or refractive surgery
84
What are zero order aberrations characterized by?
A constant, characterized by axial symmetry and a flat wavefront
85
What do first order aberrations correspond to?
Linear aberrations that describe a tilt or prismatic error
86
What types of errors are included in second order aberrations?
* Defocus (myopia and hyperopia)
* Astigmatism
87
Can higher order aberrations be corrected by spherocylindrical lenses?
No
88
What are third order aberrations?
* Coma (horizontal and vertical)
* Trefoil (triangular astigmatism with base along the x or y axis)
89
What types of aberrations are included in fourth order aberrations?
* Spherical aberration
* Tetrafoil
* Secondary astigmatism (oblique/irregular astigmatism)
90
When are fifth through tenth order aberrations important?
Only important with extremely dilated pupils
91
Fill in the blank: Zero order aberrations are characterized by _______.
axial symmetry and a flat wavefront
92
True or False: First order aberrations can be described as linear aberrations.
True
93
94
95
Net retinoscopy findings are plano-1.50 x 180. After performing JCC, patient accepts additional -1.00D at axis 180. How should the sphere be adjusted?
Increased by +0.50
* for every 0.50 D change in astigmatism, spherical component should be altered by 0.25D in the opposite direction
* ensures the circle of lease confusion remains on the retina (point where the image of a point source is mist clear, despite lens not perfectly focusing all rays)
96
When unpolarized light reaches a polarizer, the intensity of the transmitted light with respect to the intensity of the incident light is what percentage?
50% or 1/2
97
What is a shadowscope used for?
To inspect several aspects of rigid gas permeable contact lenses
98
What magnification does a shadowscope provide?
About 20x magnification
99
What does a shadowscope project onto a glass screen?
The contact lens with a reticule for measurements
100
List three evaluations that a shadowscope is commonly used for.
* Evaluating the contour of the contact lens
* Measuring the thickness of the edge of the contact lens
* Measuring the overall diameter of the lens
101
What types of damages can a shadowscope reveal in contact lenses?
Scratches, cracks, or nicks in the edge of the lenses
102
What is the function of a radiuscope?
To measure the base curve of a rigid gas permeable contact lens
103
What does a V-channel gauge measure?
The overall diameter of the contact lens
104
What is a 7x comparator?
A handheld measuring magnifier
105
What measurements can a 7x comparator be used for?
* Overall diameter
* Optic zone diameter
* Peripheral curve diameter
106
What is the primary use of a lensometer?
To measure the power of the contact lens
107
What is a shadowscope used for?
To inspect several aspects of rigid gas permeable contact lenses
108
What magnification does a shadowscope provide?
About 20x magnification
109
What does a shadowscope project onto a glass screen?
The contact lens with a reticule for measurements
110
List three evaluations that a shadowscope is commonly used for.
* Evaluating the contour of the contact lens
* Measuring the thickness of the edge of the contact lens
* Measuring the overall diameter of the lens
111
What types of damages can a shadowscope reveal in contact lenses?
Scratches, cracks, or nicks in the edge of the lenses
112
What is the function of a radiuscope?
To measure the base curve of a rigid gas permeable contact lens
113
What does a V-channel gauge measure?
The overall diameter of the contact lens
114
What is a 7x comparator?
A handheld measuring magnifier
115
What measurements can a 7x comparator be used for?
* Overall diameter
* Optic zone diameter
* Peripheral curve diameter
116
What is the primary use of a lensometer?
To measure the power of the contact lens
117
Using the Feinbloom chart at 5 feet, your patient is able to read the number “7” (20/700) on the first page. What would be the corresponding visual acuity at 20 feet?
20/2800
*Feinbloom chart is calibrated for 20 feet distance, since used at 5 feet, multiply by 4 because the testing distance is 4x closer (5 x 4 = 20)
* if kept at 5 ft, would record VA as 5/700
* but at 20 feet the VA would be 20/2800 because you multiply the numerator and denominator by 4:
5 x 4= 20
700 x 4= 2800
118
Minus cylinder form lenses have the base curve on which surface?
Front or non-ocular side of a modern spectacle lens
* minus cylinders lens form has cylinder closer to the eye which minimizes marginal astigmatism when one views through peripheral lens regions
*cosmesis is also improved with base curve as front surface of lens
119
Older lenses had the base curve as the back surface of the lens with the cylinder power on which surface?
Front side, making them plus cylinder form
120
What is the secondary focal point (F or F2)?
The point in which light converges or the point from which light appears to diverge, depending on the refracting surface type.
## Footnote
This point is associated with the refraction of light as it enters the secondary medium.
121
What convention is typically used when solving optical problems?
A linear sign convention where light is assumed to travel from left to right.
## Footnote
Distances to the right of a surface are positive, while those to the left are negative.
122
In the linear sign convention, how are distances measured from the surface categorized?
Positive when going in the same direction as light and negative when going in the opposite direction.
## Footnote
This categorization helps in analyzing optical systems accurately.
123
Can a secondary focal point be positioned to the left of the refracting surface?
Yes, it can be negative (to the left) or positive (to the right) depending on the optical system.
## Footnote
This flexibility is crucial for different types of optical setups.
124
What is the overall refractive power of the simplified model of the eye?
+60.00D
125
What is the simplified optical model of the eye called?
The 'reduced eye'
## Footnote
The 'reduced eye' is used to solve certain optical problems due to the complexity of the actual eye's optical system.
126
What is the radius of curvature of the refracting surface in the 'reduced eye'?
+5.55 mm
## Footnote
This is the value used to describe the curvature of the spherical refracting surface.
127
What is the index of refraction of the aqueous humor in the 'reduced eye'?
n = 1.333
## Footnote
Aqueous humor is the clear fluid in the eye that helps maintain intraocular pressure.
128
Where is the single nodal point located in the 'reduced eye'?
At the center of curvature of the refracting surface
## Footnote
The nodal point is a crucial point in optical systems where light rays converge.
129
What is the axial length of the 'reduced eye'?
22.22 mm
## Footnote
This is the distance from the front to the back of the eye model.
130
What is the overall refractive power of the 'reduced eye'?
+60.00 D
## Footnote
This value represents the eye's ability to bend light and focus images.
131
How can the refractive power of the 'reduced eye' be calculated?
Using the equation F = (n' - n)r
## Footnote
Where F is the refractive power, n is the index of refraction of the primary medium, n' is the index of refraction of the secondary medium, and r is the radius of curvature.
132
Fill in the blank: The equation for calculating the refractive power is F = (_______)r.
(n' - n)
## Footnote
This represents the difference in the indices of refraction of the two media.
133
True or False: The principal planes of the 'reduced eye' are coincident with the refracting surface.
True
## Footnote
This simplifies the optical model by aligning the principal planes with the refracting surface.
134
What is illuminance?
Illuminance is a measure of the amount of luminous power falling onto a surface.
## Footnote
Illuminance is typically measured in lux.
135
What does total illuminance depend on?
Total illuminance does not depend upon any properties of the surface, only the source from which the lumens are being emitted.
## Footnote
This means that the material or color of the surface does not affect the illuminance.
136
Fill in the blank: The amount of snow falling is independent of the surface onto which it falls, but only depends upon the total quantity of _______.
snow emitted from the clouds.
137
True or False: The properties of a surface affect the total illuminance measured on it.
False.
## Footnote
Total illuminance is influenced solely by the light source.
138
110 degrees
139
What is the phi phenomenon?
An illusion of motion created by flashing lights in sequence within a timed interval (60-200 milliseconds apart)
## Footnote
The phi phenomenon is often used in advertising to create the illusion of moving signs.
140
What is stroboscopic motion?
A form of apparent motion created by displaying a sequence of images or lights in rapid succession
## Footnote
This technique relies on the persistence of vision to create the illusion of continuous motion.
141
What is Troxler's effect?
The phenomenon where the surrounding background blends together when the eye is fixated on a point in space
## Footnote
The eye is always moving, but the fixation causes surrounding details to fade.
142
What is the best example of Troxler's effect?
A figure with two superimposed squares, where the smaller square disappears when fixating on an X in the center
## Footnote
The border between the squares becomes blurred, making them appear as one uniformly-colored square.
143
What causes the perception of Mach bands?
The augmentation of high spatial frequencies at transition zones between colors
## Footnote
Mach bands are typically observed in smooth transitions from white/gray to black.
144
Fill in the blank: The phi phenomenon creates an illusion of motion by flashing lights in _______.
[timed sequence]
145
True or False: Troxler's effect can occur without eye movement.
False
## Footnote
The eye is always moving, but fixation contributes to the effect.
146
What is the significance of brightness in Troxler's effect?
It is the sole distinguishing factor when the smaller square disappears during fixation
## Footnote
The perception relies on the contrast in brightness between the squares.
147
What visual system phenomenon creates bands during smooth transitions?
Augmentation of high spatial frequencies
## Footnote
This phenomenon is responsible for the perception of bands at transition zones.
148
What is the type of masking where the mask is presented before the target?
Forward masking
## Footnote
Forward masking involves presenting the mask first to interfere with the visibility of the target.
149
What is the type of masking where the target is presented first followed by the mask?
Backward masking
## Footnote
Backward masking occurs when the target is displayed before the mask, which is usually brighter.
150
What type of masking occurs when the mask and target are presented at the same time?
Simultaneous masking
## Footnote
Simultaneous masking involves the simultaneous presentation of both stimuli.
151
What is metacontrast in relation to backward masking?
A type of backward masking where stimuli are spatially adjacent
## Footnote
In metacontrast, the mask surrounds the target without occupying the same space, such as an O surrounding an x.
152
What does the name of the masking type indicate?
The location of the mask relative to the target
## Footnote
The masking type (forward, backward, simultaneous) is determined by whether the mask precedes, follows, or coincides with the target.
153
Fill in the blank: In _______ masking, the mask is presented before the target.
forward
## Footnote
Forward masking is characterized by the mask's presentation before the target.
154
Fill in the blank: In _______ masking, the target is presented first followed by the mask.
backward
## Footnote
Backward masking involves the target being shown before the mask.
155
True or False: Metacontrast is a form of simultaneous masking.
False
## Footnote
Metacontrast is a form of backward masking, not simultaneous masking.
156
What is the primary purpose of masking in visual perception?
To gather information on how the visual system processes spatial and temporal information
## Footnote
Masking helps researchers understand visual processing by presenting two stimuli.
157
Formula for effective magnification (for hand held magnifiers)
M= (d) x F
M: magnification
d: object distance
F: focal power of lens
*assume reference distance of 25cm if not given
Aka rated magnification, standard magnification or nominal magnification
158
Image jump formula
(perceived by patients when crossing segment top in down gaze for a multifocal lens)
P = d x F
*prentice rule, only depends on ADD power
P: base down prism, perceived image jump
d: distance between segment optical center and top of segment
F: add power
159
160
Coma aberration
Off-axis point sources of light to appear as comet-like shapes with a tail instead of a sharp point
161
Radiant power units
Watt
162
Luminance units
Candelas/ meter^2 or foot-lamberts
* luminous intensity that is emitted given direction from a surface per unit
163
Illuminance units
Lumens/meter^2 (lux) or lumens/foot^2 (foot-candles)
164
Luminous power units
Lumens
* total amount of light power that is generated by a source
165
Luminous intensity units
Lumens/steradian (Candelas)
166
What is chromatic aberration?
A type of distortion in which a lens is unable to focus all wavelengths of light on the same convergence point.
## Footnote
Chromatic aberration occurs due to the varying refractive index of mediums with different wavelengths.
167
What causes chromatic aberration?
The refractive index of any medium (other than a vacuum) varies with wavelength.
## Footnote
Shorter wavelengths (blues) bend more, while longer wavelengths (reds) bend less.
168
What is longitudinal chromatic aberration?
Variation in the image location due to chromatic aberration.
## Footnote
This occurs when different wavelengths focus at different points.
169
What is lateral chromatic aberration?
Variation in the image size due to chromatic aberration.
## Footnote
This affects how the image appears across different wavelengths.
170
What is the ideal positioning of the retina during subjective refraction?
Centered between the image point for the shorter and longer wavelengths.
## Footnote
This balance is crucial for clear vision.
171
What does the Red-Green test assess?
It determines whether the retina is centered properly between the image points of different wavelengths.
## Footnote
It helps identify the need for lens adjustments.
172
If a patient sees clearer letters on the red side, what does this indicate?
The center point is too far in front of the retina.
## Footnote
A minus lens will improve this balance (Red Add Minus-RAM).
173
If a patient finds the green side sharper, what adjustment is needed?
A plus lens will shift the balance.
## Footnote
This indicates the center point is too far behind the retina (Green Add Plus-GAP).
174
What principles does the Red-Green test rely on?
The principles of chromatic aberration.
## Footnote
Understanding how different wavelengths interact with the lens is essential for this test.
175
What angle is the illumination system placed at for sclerotic scatter?
Roughly 60 degrees from the oculars
## Footnote
Sclerotic scatter is used to observe corneal abnormalities.
176
What is the beam width used for sclerotic scatter?
Roughly 1 mm in width
## Footnote
This beam illuminates the temporal limbus.
177
What abnormalities can be observed with sclerotic scatter?
Central corneal clouding
## Footnote
This technique is effective for identifying corneal issues.
178
What beam width setting is used for an optic section?
Roughly 0.5 mm
## Footnote
This allows for depth localization of the cornea.
179
What is the purpose of an optic section?
To effectively 'slice' the cornea into its constituent layers and for angle estimation
## Footnote
This technique aids in detailed corneal examination.
180
How is diffuse illumination achieved?
By increasing the aperture size to greater than 4 mm in width
## Footnote
This allows for gross evaluation of structures.
181
What structures can be evaluated using diffuse illumination?
Lids, lashes, and conjunctiva
## Footnote
This technique provides a wide view of anterior eye structures.
182
What is a conical beam used for?
To assess the anterior chamber for possible cells and flare secondary to inflammation
## Footnote
This technique helps in identifying inflammatory reactions.
183
How is a conical beam achieved?
By making the aperture width and height of the light housing as small as possible
## Footnote
Focus is shifted back and forth to evaluate the anterior chamber.
184
What should be done to maximize visibility when using a conical beam?
Turn off all other sources of light in the examination room
## Footnote
The examiner should also be dark-adapted for better visibility.
185
What is specular reflection used to evaluate?
The quality of a surface such as the corneal endothelium or tear film
## Footnote
This technique provides insights into the health of these surfaces.
186
What angle should the oculars create with the illumination system for specular reflection?
45 degrees
## Footnote
This angle is crucial for optimal imaging.
187
What is the beam width for specular reflection?
About 1 mm
## Footnote
This beam width is essential for clear evaluation.
188
How is the image achieved in specular reflection?
Observable through only one ocular at a time
## Footnote
This technique enhances the quality of the observed image.
NBEO Part 1
flashcards
Decks in class (22)
# Cards
-
Anatomy419
-
Ocular Disease218
-
Ocular Emergencies1
-
Pharmacology99
-
Slit Lamp Techniques18
-
Biochemistry/ Cell Biology/ Microbiology146
-
Diagnostic Testing8
-
Random Knowledge29
-
Systemic Health/Disease185
-
Optics188
-
Neuro-ophthalmic11
-
Vision Science103
-
Refractive/ Glaucoma surgeries31
-
Ocular Motility/ Binocular Vision46
-
Peds/pregnancy16
-
Practice Questions1
-
Physiology27
-
Cumulative 1499
-
FORMULAS30
-
Cumulative 2500
-
Cumulative 3145
-
It’s All Relative8
