A-Scan & Optical Biometry

Question 1

High Frequency Probe (35 mhz)

Answer 1

short wave length > used for anterior chamber

Question 2

Low Frequency Probe (10 mhz)

Answer 2

long wave length > used for prosterior chamber

Question 3

Velosity

Answer 3

speed at which sound travels via media

Question 4

Refelctivity

Answer 4

strength of echo

Question 5

Gain

Answer 5

adjustment of amplification of the echos

Question 6

High Gain

Answer 6

loss of information

Question 7

Low Gain

Answer 7

loss of definition = improve resolution but decreased sensitivity

Question 8

A-Scan

Answer 8

produces a one dimensional linear image

Question 9

B-Scan

Answer 9

produces a two dimensional image

Question 10

What does A-Scan measure?

Answer 10

axil length, from cornea to macula (anterior chamber depth, thickness of lense and lenghth of prosterior chamber)

Question 11

Types of Axial Biometry

Answer 11

ultrasound waves

light waves & laser

Question 12

Ultrasonic Pachymetry

Answer 12

measurement of cornea thickness

Question 13

Phakic

Answer 13

natural lense

Question 14

Psiedophakia

Answer 14

lense implant

Question 15

Aphakic

Answer 15

abscence of lense

Question 16

Types of Opticle Biometry

Answer 16

contact biometry (need anesthetic drops)
immersion biometry (need anesthetic drops)

Question 17

Axial length between the two eyes

Answer 17

.3mm of each other

Question 18

Immersion Biometry Shells

Answer 18

Prager shell (fluid delivered via tube)
Hansen shell (pour fluid into top of shell)