Ametropia/Optics/ Accommodation/Vergence/Oculomotor/Low Vision/Amblyopia/Strabismus/Color Vision/Visual Human Development Flashcards
Please note, there is information left out based on my own personal knowledge.
1
Q
BIO vs. DO, what is the difference in between the two for field of view, depth of focus, magnification and image?
A
BIO will have: Larger FOV Larger Depth of focus Smaller magnification Inverted image
2
Q
What is the item that moves in a lensometer? What is the formula for lensometry?
A
Target moves.
x = f^2 (F)
Note: all must be in meters.
3
Q
Your trying hand neutralization and notice with motion. What type of lens?
A
Minus
Note: Against motion is a plus lens
4
Q
What does the Cornea mimic?
a. Concave lens
b. Convex lens
c. Concave mirror
d. Convex mirror
A
d. Convex mirror
5
Q
Lens clock formula?
A
F = (index of lens - 1)/(index of lens clock calibration) x F based on lens clock finding
6
Q
Tolerance perimeter for lens thickness?
A
+/- 0.3mm
7
Q
Tolerance for warpage?
A
1.00D
8
Q
What is the BC tolerance?
A
+/- 0.75D
9
Q
What is the impact resistance based on ANSI Z80.1?
A
5/8 steel ball from 50in
10
Q
What does the “H” marking mean on safety eyewear?
A
Smaller head
11
Q
What is the symbol for impact rating?
A
”+”
12
Q
Where is the base curve located on a lens?
A
Front
13
Q
Lens thickness formula
A
F= (2(ns-n1)s)/h^2
14
Q
Minimum Blank Size
A
M=ED+2(d)+2mm
15
Q
If the seg appears too high, what should be done to the pantoscopic tilt?
A
Increased
16
Q
What are the index of refraction and abbe value for CR-39, Polycarbonate, High Index and Trivex?
A
CR 39 - 1.498 and 58
Poly - 1.586 and 30
H.I. - 1.54 to 1.66 and 32 to 47
Trivex - 1.53 and 43 to 45
17
Q
Which type of rays bend the most in Spherical Abberations?
A
Marginal
18
Q
Which type of rays are bent the most in chromatic abberations?
A
<300nm (Blue)
19
Q
What is the best way to get rid of Chromatic Abberations?
A
Achromatic Doublet
20
Q
Unit of prism power formula
A
Prism = y (shifting of light) /x (wall to prism)
Note: y must be in cm and x will be in m
21
Q
Apical angle formula?
A
d=A(n-1)
22
Q
Prism thickness formula
A
Prism = (100g(n-1))/l
23
Q
Prentice rule
A
Prism = dF
24
Q
Spectacle magnification formula
A
Shape factor vs Power factor
25
What is the shape factor formula?
SF = (1)/1-(t/n)Front surface power
26
What is the power factor formula?
PF = (1)/1-hF
Note: F is the back vertex power of the lens
27
What are the trends when increasing h, t, base curve and n in Plus lenses?
Increase SM with an increase in h, t, base curve BUT a decrease in SM with an increase in n'
28
What are the trends when increasing h, t and n in minus lenses?
Decrease in SM BUT an increase in SM when t is increased.
29
Axial ametropes are best corrected with?
Glasses ....look into Knapp's law for further information
30
Refractive ametropes are best corrected with?
CTL's
31
Regarding the retinal images size, put in from largest to smallest image size based on AXIAL length?
Myope>Emmetropic>Hyperopic
32
Regarding the retinal images size, put in from largest to smallest image size based on uncorrected refractive ametropes?
All retinal images are the same
33
Which has a larger retinal image size: a spectacle corrected refractive hyperope or a spectacle corrected refractive myope?
Spectacle corrected refractive hyperope
34
What is the formula for Reflectance?
R= ((n2-n1)^2)/((n2+n1)^2)
35
Contact lens formula?
Fv = F2 + (F1)/1-(t/n)F1
36
How much is there internal astigmatism?
-0.50 x 090
37
For 0.4mm in OZD change, how much should the BC change?
0.25D
38
Normally, water will carry oxygen to a high concentration, but why is that the opposite for SiHy lenses?
Silicone carries the oxygen faster than water.
39
Which refractive error has to accommodate more in Contact lenses?
Myopes
40
In low vision, what term describes the change in distance for magnification change?
RDM
41
Which type of magnifier requires no Add?
Hand magnifier
42
Formula for tube length?
d = fobj + foc
43
Magnification of telescopes formula?
M = -Foc/Fobj or M = dent/dex
44
What is the final image produced by a Kaplerian telescope?
Inverted and Magnified
45
Where is the exit pupil located in a kaplerian telescope?
Outside telescope, thus producing a DIM but large field of view.
46
What is the final image produced in a Galilean telescope?
Upright and Magnified
47
Where is the exit pupil in a Galilean telescope?
Inside the telescope, thus producing a small field of view but brighter image.
48
Due to limitation of length in a Galilean telescope, What is the maximum magnification possible to achieve?
4x
49
What are 2 solutions or ways to improve to view an object at near with a telemicroscope?
Increase tube length and/or add a reading cap
50
What type of telescope is excellent for increasing field of view for patients with Glaucoma or RP?
Reverse telescope
51
What is considered to be legally blind?
20/100 in the better seeing eye or VF diameter is 20 degrees or less in the better seeing eye.
52
What is considered severe low vision loss?
20/200 to 20/400
53
Low vision pts with a central scotoma will have what type of viewing?
Eccentric viewing
54
Formula for light house method?
Working distance x 2.5D
55
What type of filters are used to decrease glare?
Neutral Density filter & Blue blocker tint
56
Where is the far point of a hyperope?
Behind the retina
57
What is absolute hyperopia?
Hyoperopia is too large to be neutralized by accommodation.
58
What is the formula for measuring acuity from Allen vision test to Snellen?
x/30
59
What is static retinopathy?
Retinopathy behind a phoropter
60
Mneumonic for Duochrome testing?
RAM GAP
Red: Add minus
Green: Add plus
61
3 reasons to do cycloplegic refraction?
1. Child with Strab
2. Significant Esophoria
3. Young adult complaining of headaches but no correction of hyperopia
62
What is the percentage of a person using their accommodative ability?
50%
63
An aphakic pt will display a ring scotoma, which appears and re-appears. What is this phenomenom called?
Jack in the box effect or Jumping effect
64
What is equally mixed astigmatism?
A special case of mixed astigmatism where the circle of least confusion falls on the retina.
65
Where is the major meridian for "WTR"?
Vertical "90 +/-30 degrees"
Note: Don't get confused with a SRx. If the SRx notes a +3.00 -1.00 x 090; then this would be considered a vertical axis (Not meridian) thus this SRx would be considered a "ATR"
66
What is the definition of Absolute Hyperopia?
Cannot overcome with accommodation
67
Where is the farpoint of an hyperopic pt?
Behind the Retina
68
What is the working distance when checking Interpupillary distance?
30 cm
69
How to convert Allen Vision test to Snellen?
x/30
70
How to convert to convert snellen to MAR?
20/x = MAR
71
What is the Corneal thickness?
550um
72
What would be axis when confirming with Stenopaic Slit?
Parallel to the actual axis point
Ex. If you get -0.50 @ 180 (with the slit on the 180 meridian) and -1.50 @090 (with the slit on the 090 meridian); the SRx will be -0.50 -1.50 x 180.
73
When considering a cycloplegic, either for Latent Hyperopia or any eye turn, when should you prescribe the full SRx?
Any eyeturn. Never give the full latent hyperopic patient, approx. 1/2 should be given.
74
What is the JND for a pt with VA of 20/150?
+0.75 to -0.75
75
In directly, what fusional vergence are you testing when conducting NRA?
PFV (Positive Fusional Vergence)
Think about it. If you give + lens (NRA testing) you are relaxing accommodation, thus you require the eyes to converge (BO) more, hence causing PFV.
76
Which refractive product is the best option for children with Aphakia?
RGP
The reason for this is due to the development of the eye while keeping a healthy a viable option for tear exchange vs. SiHy lenses.
77
Doing Alternating cover test, pt's eye moves outwards. What is the condition and which direction of the cover paddle will move based on the pt's presspective?
Esophoria and Opposite direction
Note: Exophoric pt's will notice the same direction as the cover paddle.
78
Fixation disparity curve, which will the shift of the curve be if a pt becomes more esophoric?
Up and to the Right.
Exophoric are down to the left and Normal are diagonal straight through the center going from top left to bottom right.
79
What are the 2 best ways (based on literature) to measure Anisokonia?
1) The Space Eikonometric method is based on binocular space perception.
2) The Direct Comparison method is based on directly comparing perceived image sizes between the two eyes.
80
What type of Ellipsoid is the Cornea prolate or oblate?
Prolate; means flattening out to the periphery.
81
What is the peak wavelengtgh for the Photopic system?
555 nm
82
What is the peak wavelength for the Scotopic system?
505 nm
83
Based on visual axis, where is the fovea placed accordingly to the ON?
Infero Temporal
84
What is the term when PR's are shifted according to light?
Stiles-Crawford
85
What are the 3 tests for visual spatial dysfunction and what do they test specifically?
1) Piaget test (Laterality)
2) Jordan test (Directionality)
3) Standing Angels in the Snow (Bilateral Integration)
86
What is Maxwell's Spot?
Central vision testing; red spot detected away from the fovea
87
What is Haidinger's brush?
Central vision testing; using birefringence testing and you are looking for where Haidinger's brush sits on the retina.
88
What are Moore's lighting streaks associated with?
Retinal tear or Retinal detachment
89
What are blue arcs of the Retina?
Physiological blind spot; Dim light in a dark room.
90
What are Phosphenes?
Mechanical rubbing
91
Formula for estimated pinhole VA?
MAR = 2.33/d
92
Formula for primary focal power of a thin lens?
f= - (n/F)
This is due to the primary focal point on the left side of the lens (think of ray tracing)
93
What is the apparent depth formula? Where do you expect the object to be in a medium that is larger than the area viewing from?
n1/l1 = n2/l2
Object will be further away, as any time you go from a small to a larger medium, the object will tend to be further away. Therefore the image will appear closer than the object.
94
Nodal point, different from the nodal ray, is located at what optical area?
Center of Curvature
95
Formula for Angular Magnification and what does this apply too?
Angular Mag = Eyepiece/Objective
This is used to subtend the image using a telescope. For instance, you are looking at the moon, the first lens when you looking at the moon will have an angle, subjective to the Objective lens. The second lens, the eyepiece lens, will create a different angle.
96
Formula for Lateral Magnification?
M=i/o
97
Effective Vergence Formula?
Fe = F1+F2 - t/n (F1xF2)
98
For a thick lens system, what is the vertex power formula?
F2 + F1/(1 - t/n (F1))
99
Where is the exit pupil located in a Keplarian Telescope?
Outside
100
Where is the exit pupil in a Galillean telescope?
Inside
101
Definition of Aperature stop?
Physical entity restricting light
102
Definition of Field stop?
Limits size of object that can be imaged; associated with ports
103
When using a minus lens, what happens to the Field of View?
Increases FOV. The opposite occurs in a plus lens.
104
Describe the Circle of least confusion?
Halfway point of lens, Dioptric point met in the middle of the interval of sturm.
Ex. +5.00 +2.00 x 180
+5.00 +7.00 = +12.00
+12/2 = +6 and convert into cm, therefore 17cm
105
Describe Interval of Sturm?
Area that covers the sphero-cylinderic area.
Ex. +5.00 +2.00 x 180
1/5 - 1/7
0.20 - 0.14 = 0.6mm = 6 cm
106
Formula for Lens/Mirror Combo?
F = 2F1 +F2
107
Formula for Mirror?
F=2n/f
Note: Convex mirrors have a negative ROC
108
What needs to be true for Total Internal reflection to occur based on index?
n1>n2
As the light passes through the medium and passed the critical angle, only then will TIR occur.
109
What are the most impactful abberations in order?
Curvature of Field, Distortion and Oblique Astigmatism.
Oblique Astigmatism >COF >Distortion
110
What is the definition of Oscillopsia?
Standing still but the environment feels like it moves around you
111
What is an example of Vertigo?
Environment feels still but you feel your body is moving
112
At the Spiral of Tillaux, which EOM is furthest from the limbus?
Superior Rectus
Note: Medial Rectus is the closest
113
What is the threshold for VOR?
<30 sec
114
What is the threshold when OKN starts?
>30 sec
115
What does it mean when small movements occur with associated steady fixation?
Equal magnitude of head movement but in the Opposite direction
116
What is the function of endolymph and where is it located?
Function: Assist in VOR
Location: Semi-Circular canal
117
What is a obvious symptom associated with Spasmus Nutans?
Head nodding (and Pendular Nystagmus)
118
Which deviation will display a comitant clinical sign, CN 6 palsy or DI?
DI will show, since the vergence system is still functioning and image is still on the fovea in all directions.
119
What type of nystagmus is characterized by a slow drift but named in opposite direction?
Jerk nystagmus
120
What are three tests that help in evaluatiing Nystagmus?
Doll Head Maneuver, Caloric test and Rotational Chair (20 sec)
121
While using Visuoscopy, you notice the grid to superior to the fovea. What is the issue you have?
Superior Eccentric Fixation
122
When conducting the Hirschberg test, what are the three criteria you are looking for in any deviation?
1) Look at the light and according to center of the pupil.
2) Measurement of Angle Lambda --> ESO (+) and EXO (-); This is the only test we can clinically measure
3) 1mm of deviation in approx 22PD
123
Which types of medications are known to cause CE?
Cholinergic Agonist (Physostigmine, Pilocarpine, Sulfonamides and High dose of Vitamin B)
124
What is characteristic in Dorsal Midbrain Syndrome?
Slow down movement on Abduction
125
Where is See-Saw Nystagmus?
Parasellar lesion - Pituatary Gland
126
Where are the 3 areas where saccades are initiated?
Occiptoparital Junction, FEF and Superior Colliculus
127
At what point will a Pursuit transition to a Saccade?
50 degrees/second
128
What is the definition of Tonic Vergence?
Measurement or Position of line of sight of each eye when stimulus for fusion at distance.
129
Spectacle corrected hyperope vs. Spectacle corrected Myope, which one creates a larger retinal image size?
Spectacle corrected Hyperope
130
What is anatomical Anisokonia?
PR density; causing change in the retinal size.
Note: Don't be confused by the Stiles Crawford Effect, which displays alignment of PR's based on light angle
131
What happens to the Spectacle magnification when a Plus lens is added to a system?
Larger Relative Size Magnification (RSM)
132
Conducting Bruckner's test, you notice a dark retina. What does that mean?
Media opacity
133
AC/A Ratio formula
PD cm +NFD mm (Phoria near - Phoria distance)
Note: Eso + and Exo -
134
Gradient AC/A
(P1-P2)/(SA1 - SA2)
135
Relative Size Magnification formula
New Object Size/Original Object Size
136
Visual acuity testing for MAR in Low Vision
MAR = 20/x
137
Why is ETDRS liked in Low Vision?
Logmar setup
138
What is Kestenbaum's rule and why is it important?
Reciprocal of Snellen VA to determine add power at near.
139
Does Intermittent Strabismus cause Amblyopia?
No, only constant
140
What is the pathology of Amblyopia?
Loss of binocular cells in the visual cortex
141
What is the critical period for Amblyopia?
7 to 9 YO
142
At which level of the brain does Suppression occur?
Visual Cortex
143
3rd Degree fusion is usually what type of binocular attribute?
Stereopsis
144
2nd Degree fusion is usually what type of binocular attribute?
Worth 4 Dot or Flat Fusion
145
Which Anisometropia is worse, Hyperopic or Myopic?
Hyperopic Anisometropia, this is due to a clear image for a myope at 2 distances
146
What type of Eccentric Fixation is opposite to direction of deviation?
Paradoxical EF
Ex. Esotrope & Temporal Fixation point
147
List the Anisometropia range for Myopia, Hyperopia and Astigmatism.
M-3.00 and larger
H-1.00 and larger
A-1.50 and larger
148
List the Isometropia range for Myopia, Hyperopia and Astigmatism.
M-8.00 and larger
H-5.00 and larger
A-2.50 and larger
149
What is the most common type of ARC, other than Normal ARC?
Harmonious ARC
| A=H and S=0
150
Pt had a larger angle of anomaly than the objective angle. What type of ARC?
Paradoxial ARC
151
Angle of anomaly is smaller than the angle of objective. What type of ARC?
Unharmonious ARC
152
You conduct the After image test (cortical phenomenon), the OS (normal eye) is flashed with a Horizontal line and the OD (Deviated eye) is flashed with a vertical line. If the patient reports the vertical line to the left, what type of deviation does the patient have?
OD ESO.
Don't confuse this with anything on the retina, rather a cortical issue.
153
Bagolini lenses used and pt reports a "/\" pattern. What does this mean?
EXO-Trope; since the image hits temporal retina.
154
When is the break point from Cones to Rods in wavelength during Dark Adaption?
650 nm
155
What is the critical duration in the scotopic system?
100m/s
156
What is the critical duration in the photopic system?
10m/s
157
What is the time for Cones to be saturated during dark adaption?
10 mins
158
What is the time for Rods to be saturated during dark adaption?
30 mins
159
What is the flash duration of Broca Sulzer effects?
50m/s to 100m/s
160
What is the Brucke-Bartley Effect?
A flickering of 10Hz appears brighter than a steady light of the same luminance
161
How do you notice the Purkinjee tree?
Closed eye and shine light
162
Name a method of Ascending Limit testing?
Dark Adaptation
163
Name a method of Descending Limit testing?
Visual Acuity
164
Name a Stairstep method?
Automated Perimeter
165
A relaxed pt will display what type of issue throughout Perimetry?
False Positive
166
A Strict pt will display what type of issue throughout Perimetry?
False Negative
167
What are the 2 important factors when summing up Total Incidence when measuring disease in a population?
True Positive
| False Negative
168
Trauma to the ON will cause what type of color defect?
Red-Green
169
What is the most common color defect?
Protanolmaly
170
Inherited color anomalies are usually what type of inheritance pattern?
X-Linked Reccessive
171
What does an acquired blue-yellow color defect indicated?
Retina or Macula, has been impacted.
172
What is the definition of linearly polarized light?
Magnitude changes but the direction stays the same
Circular and Elliptical polzarization are the opposite
173
Explain Brewster's law
PERPINDICULAR reflect light, will become refracted
174
What is the general desired effect of polarization?
Cutting away 1/2 of the light, thus the formula--> I=I/2
175
Explain Malus law
Intensity at a given point can be calculated based on the angle.
Ex.
Q: Unpolarized light at 45 degree, What is the intensity?
A: Since light is polarized at 90 degrees (which means 180 degree is absorbed, therefore the polarizer is already 50%) Since 45 degrees is 1/2 of 90 degrees, then it must be 1/2 of 50% of transmission.
I=I/2 at 50%
I=1/4 at 25% = 25% Transmission and 75% Absorbed
176
What type of laser is used in LASIK and PRK?
Excimer
177
Which laser is used when steepening the cornea but burning the mid-periphery?
Conductive Keratoplasty
178
Which type of balancing test is measured via Transverse Abberation?
Duochrome Test
179
In the periphery, would Lateral Chromatic Abberation increase or decrease?
Increase
180
How can Chromatic Abberations be elimated?
With Achromatic Doublet
181
On optical lenses, where is the Base Curve located?
Front
182
Greater the Diffraction, _________ Airy's Disk and ________ the aperture size
Larger and Smaller
183
What is the primary cause of Chromatic Abberation?
Dispersion
184
What is the Juvenile onset of Myopia?
8 to 12 YO
185
What is Absolute Hyperopia?
Amount of hyperopia that cannot be overcome by accommodation.
186
How do you correct WTR astigmatism, when the steep merideian is 90 degrees?
Correct with minus lenses in the 180 meridian
187
Cortical cataracts will display what type of refractive shift?
Hyperopic shift
Note: Any peripheral cataract will display a hyperopic shift
188
When doe the lens stop changing?
9 to 10 YO
The axial length continues to grow
189
Will a hyperopic pt display esophoria or exophoria at near?
Esophoria this is due to increased accommodative convergence
190
What is the triad for a hyperopic pt?
Hyperopia, miotitc pupils and Esophoria
191
What is the formula for Angular Threshold?
Snellen Denominator = 600/CPD
192
Which type of refractive error is associated with Angle Closure?
Hyperopia
193
How tall should a 20/200 letter be at 6m?
87 mm taller
20/200 = 10' and since a standard letter is 5' gaps tall, then 5 x 10 = 50 min of arc. Then using 6m x tan(50/60 degrees)= 0.087m
194
Why is Bailey Lovie considered the gold standard in Low Vision?
Constant spacing between letters and it can be moved to different distances for low vision patients.
Note: A Larger LogMar score on Bailey Lovie is a worse score
195
If a pt get all except 2 letters on a line on the Bailey Lovie chart, what is their LogMAR score?
0.04
(Line score + 2) x 0.02/letter = 0.04
196
What is the order when doing refraction with the JCC?
Axis, Power and then Axis again
197
What is the best way to treat Aphakic pt's?
CTL's
This is due to magnification, as a spectacle lens will created a significantly larger image vs. CTL
198
Which two types of aberrations occur only with a large aperture system?
Spherical Aberration and Coma
199
An aphakic pt will become more esophoric or more exophoric?
Exophoric
200
What is the theory behind Aphakics having issues with glare?
Since the posterior capsule is still retained, it will contain small particle or opacities that reflect light and bounce around leading to Glare. Also the pt will experience the input of Blue light entering the eye more.
201
What is the most beneficial type of Soft CTL a pt should wear if they are an aphake due to Senile Cataracts?
Extended wear CTL's. This is due to benefit of one package opened for an elderly pt whom may have senile issues related to bones and muscle issues.
202
Where should a Bifocal line be set in pt's?
Should be placed on the beginning of the lower lid.
Note: Early Accommodative Esotropia pts should have their pupil bisected
203
How many refractive surfaces and index of refraction are their in the Reduced model eye?
One refractive and One index
204
Which other axis or rays do Nodal Rays cross?
Optical axis
205
The enterance pupil is the _______ of the aperture stop?
Image
206
In the reduced eye, where do the Nodal Points coincide with?
Center of Curvature
207
What is the anterior and posterior radius of the Cornea?
7. 80 mm Anteriorly
| 6. 50 mm Posteriorly
208
What angle is measured in Eccentric Fixation?
Kappa
209
What is the order of Purkinje fibers from Largest to Smallest?
3, 1, 2, 4
210
What are three aberrations the pupil reduces when becoming smaller?
Chromatic Aberrations, Spherical Aberrations and Oblique Astigmatism
211
If the pupil decreases from 8mm to 2mm, what is the amount of light that is decreased by the eye?
By a factor of 16
212
What is a corneal entopic phenomenon?
During a blink, tears naturally go upwards due to eyelid movement, however your eye perceives them to float down.
213
Which image quality aberration is considered a 3 axis astigmatism?
Trefoil
214
What is the definition of Modulation Transfer Function?
Magnitude of the Optical Transfer Function. Tells you the ability of adjacent pixels to change from black to white due to spatial frequency.
215
Which law describes the adding wavelengths together?
Abney's Law
216
Excessive exposure to UV-___ to solar keratitis?
UV-C
Note: UV-A and AV-B will be mostly absorbed by the lens.
217
What type of cataracts are associated with IR radiation?
Glass Blower Cataracts
218
What is the lens clock formula?
F = F(Ntrue - Nair)/(Nclock-Nair)
219
What is the formula for ideal base curve for a minus lens?
Minus = SE/2 + 6.00
220
What is the minimum thickness of a Safety lens?
3mm
221
Minimum Blank size formula
MBS = ED + 2d
222
What is the formula for ideal base curve for a Plus lens?
Plus = SE +6.00
223
What is the best way to correct Spherical Aberrations?
Achromatic Doublet
224
What are the two most critical aberrations in lens design?
Marginal astigmatism and Curvature of Field
225
How are Ghost images from spectacles reduced? 3 options
Increase faceform, Decrease vertex distance and Decrease eye size
226
What is the maximum add for a PAL, Flat top and Bifocal?
Pal: +3.00
Flat top: +6.00
Round seg: +30.00
227
Which frame material is known to carry memory?
Optyl
228
Which type of frame material requires hot water for bending?
Nylon
229
Which 2 prominent frame materials are known as hypoallergenic?
Optyl and Propionate
230
What is the difference between Minus and Plus lens when effectivity is an issue?
Minus lens can be corrected by Decrease center of thickness
231
Which regulatory agency is associated with lens impact resistance?
FDA
232
What is the spherical tolerance?
+/-0.13D @6.50 and below; 2% @>6.50
233
What is the cynlindrical tolerance?
+/- 0.18D @ 8.00 and below; 2% @ >6.50
234
What are most Safety Rx thickness?
3.0mm for plastic while Polycarbonate is 2.0mm
235
What is the lens impact on Z87.1 lenses?
1" steel ball dropped at 50" onto lens surface. Lens cannot break
236
Which safety organization regulates the requirements of Z87.1 in workplaces?
OSHA (Occupational Safety and Health Administration)
Remember that OSHA is for workplace safety
237
Formula for Effective Power?
F/1+dF
238
K readings are 50D and above, what should you do to make sure you have an accurate reading while using the Keratometer?
Add +1.25 in the front of the Objective lens with anything greater than 50D
Note: -1.00 on <35D
239
CTL power formula?
F/1-(t/n)F + F2
240
Which instrument measures Base Curves?
Radioscope
241
Which Lens Material is known to have the best deposit resistance from Group 1,2,3 and 4?
Group 1
Note: Group 4 is the worst
242
A CTL pt gets examined and you notice blebs, which layer on the cornea are we talking about?
Endothelium
243
Which type of small movement has the fastest amplitude?
| Microdrift, Microsaccades or Microdrift
Microsaccade at 1 degree of arc and can reach 100 deg/arc sec
Note: Vergence system takes the longest
244
What is the most common cause of Congenital Esotropia?
Overacting Inferior Oblique
Note: DVD and Latent Nystagmus follow suit
245
What is the major cause of Myasthenia Gravis?
Decreased AcH receptor concentration
246
What is the cause of CPEO?
Mitochondrial Myopathy causing muscle fibrosis
247
Where is the lesion in INO?
MLF where the communication with CN 3,4 and 6 have been impacted
248
You introduce BO prism, what do you think will happen to the fixation disparity for both eso and exophoric fixation disparity?
Reduction in esophoria and inducing exophoric fixation disparity
249
What is easier to treat, High AC/A or Low AC/A?
Low AC/A, this is due to the fact the pt can compensate with accommodation.
250
Which Ciliary muscle arises from anterior choroid and run to the scleral spur?
Longitudinal; Look at an image. Radial and Circular are more interior vs. Longitudinal is further outwards
251
Which law states that an increase in brightness = an increase in intensity?
Weber's law
252
Based on Bloch's law, what is the critical duration of a rod and cone?
```
Rod = 100msec
Cone = 10 to 50 msec
```
Note: Bloch of Time (Temporal summation)
253
When light is considered to be stationary without any flicker, what law is being impliented?
Granit-Harper Law
254
What is the peak CFF in TEMPORAL CFF?
10Hz to 30Hz
Note: The peak range where no flicker is detected is 60Hz
255
What is the CFF in Rods?
20 flashes/sec
256
What is the CFF in Cones?
60 flashes/sec
257
What law is implimented when steady light seems brighter than flockering light?
Brucke-Bartley effect
258
Hue of a color is based on what property?
Wavelength
259
Saturation of a color is based on what property?
Purity
260
Brightness of a color is based on what property?
Luminosity
261
Munsell color system is based off what 3 principles?
Hue, Chroma and Value
