Optics Lecture 7

Question 1

Average axial length

Answer 1

22-24mm

Question 2

With an axial length of 20mm, we might suspect

Answer 2

Hyperopia

Question 3

With an axial length of 26 mm, we might suspect

Answer 3

Myopia

Question 4

Each mm of axial length mismatch corresponds to how much of a refractive deviation

Answer 4

2.3-3.4D

Question 5

Normal range of anterior chamber depth in adults

Answer 5

3-3.4mm

Question 6

What happens to the ACD with age; what is its “final” depth

Answer 6

Decreases; 2mm

Question 7

What 2 conditions affect ACD

Answer 7

Catarct and glaucoma

Question 8

Volume in AC

Answer 8

Between 220 and 171 +/- 36 microL (.0007 fluid ounces)

Question 9

Normal angle in adults

Answer 9

30 degrees

Question 10

What pathologies are associated with smaller anterior chamber angle

Answer 10

Cataract and glaucoma

Question 11

Which will give more detail of the cornea, pentacam or OCT and angle

Answer 11

OCT

Question 12

Measurement of pupil diameter

Answer 12

Pupilometry

Question 13

Which pupil measurement is used in determination of optical zone

Answer 13

Scotopic

Question 14

Why is it not easy to measure the cornea

Answer 14

Because it is not the same thickness everywhere (thinnest in middle, then temp, then nasal)

Question 15

Where is CCT located

Answer 15

At the pupil center (black dot in center of dashed circle)

Question 16

Where is the minCT located

Answer 16

The most orange/red area, slightly inferotemporal

Question 17

When looking at corneas, should they look the same or opposite?

Answer 17

Opposite (corneal asymmetry)

Question 18

Average range of CCT

Answer 18

520-580 microns

Question 19

When is CCT thickest

Answer 19

Upon waking

Question 20

With a thinner CCT, what is important to remember when checkin IOP

Answer 20

Underestimated

Question 21

With a thicker CCT, what is important to remember when checkin IOP

Answer 21

Overestimated

Question 22

Indications of a thick cornea

Answer 22

• Endothelial cell damage, Fuchs dystrophy

Question 23

What is the problem with scheimpflug imaging pachymetry

Answer 23

High resolution requires small depth of field

Question 24

What is the solution for the scheimpflug imaging pachymetry

Answer 24

Tilt the lens