Optics Lecture 7 Flashcards
Average axial length
22-24mm
With an axial length of 20mm, we might suspect
Hyperopia
With an axial length of 26 mm, we might suspect
Myopia
Each mm of axial length mismatch corresponds to how much of a refractive deviation
2.3-3.4D
Normal range of anterior chamber depth in adults
3-3.4mm
What happens to the ACD with age; what is its “final” depth
Decreases; 2mm
What 2 conditions affect ACD
Catarct and glaucoma
Volume in AC
Between 220 and 171 +/- 36 microL (.0007 fluid ounces)
Normal angle in adults
30 degrees
What pathologies are associated with smaller anterior chamber angle
Cataract and glaucoma
Which will give more detail of the cornea, pentacam or OCT and angle
OCT
Measurement of pupil diameter
Pupilometry
Which pupil measurement is used in determination of optical zone
Scotopic
Why is it not easy to measure the cornea
Because it is not the same thickness everywhere (thinnest in middle, then temp, then nasal)
Where is CCT located
At the pupil center (black dot in center of dashed circle)
Where is the minCT located
The most orange/red area, slightly inferotemporal
When looking at corneas, should they look the same or opposite?
Opposite (corneal asymmetry)
Average range of CCT
520-580 microns
When is CCT thickest
Upon waking
With a thinner CCT, what is important to remember when checkin IOP
Underestimated
With a thicker CCT, what is important to remember when checkin IOP
Overestimated
Indications of a thick cornea
- Endothelial cell damage, Fuchs dystrophy
What is the problem with scheimpflug imaging pachymetry
High resolution requires small depth of field
What is the solution for the scheimpflug imaging pachymetry
Tilt the lens
