UNIT TWO - Keratometer

Question 1

Keratometry Procedures Step 1

Answer 1

FOCUS THE EYEPIECE:

• turn counterclockwise until it stops
• turn clockwise until mires are in crisp focus
• STOP!! Do not jiggle back and forth to focus

Question 2

Keratometry Procedures Step 2

Answer 2

ORIENT THE PATIENT:

• explain procedure
• give patient instructions on fixation and head position
• adjust chair for patient comfort
• adjust chinrest so headrest meets patient forehead 1” above eyebrows

Question 3

Keratometry Procedures Step 3

Answer 3

ALIGN THE EYE BEING MEASURED:

• use the sighting device to find the approximate height
• locate mires and focus
• place black crosshair in the lower right hand circle
• lock

Question 4

Keratometry Procedures Step 4

STEPS 4-6 KEEP ONE HAND ON FOCUSING KNOB AT ALL TIMES

Answer 4

LOCATE A PRINCIPAL MERIDIAN

• use horizontal power drum to bring the tips of the two plus signs together
• turn axis wheel to align the two tips to form one unbroken line

Question 5

Keratometry Procedures Step 5

STEPS 4-6 KEEP ONE HAND ON FOCUSING KNOB AT ALL TIMES

Answer 5

MEASURE THE HORIZONTAL MERIDIAN

-turn the power drum to superimpose the two minus signs

Question 6

Keratometry Procedures Step 6

STEPS 4-6 KEEP ONE HAND ON FOCUSING KNOB AT ALL TIMES

Answer 6

MEASURE THE VERTICAL MERIDIAN

-turn the power drum to superimpose the two minus signs

Question 7

Keratometry Procedures Step 7

Answer 7

RECORD MEASUREMENTS (K Readings)

• horizontal power is recorded with the most horizontal meridian
• vertical power occurs in the most vertical principal meridian

Question 8

Keratometry Procedures Step 8

Answer 8

CLEAN THE HEADREST AND CHINREST OF THE KERATOMOTER

Question 9

Identify the amount (in diopters) and the type (WTR/AGT/Oblique/Irregular)of corneal cylinder indicated by the following K readings.

42.00@180/43.25@90

Answer 9

Amount of cylinder: 1.25

WTR

Question 10

Identify the amount (in diopters) and the type (WTR/AGT/Oblique/Irregular)of corneal cylinder indicated by the following K readings.

46.25@180/44.25@90

Answer 10

Amount of cylinder: 2.00

ATR

Question 11

Identify the amount (in diopters) and the type (WTR/AGT/Oblique/Irregular)of corneal cylinder indicated by the following K readings.

42.25@05/42.25@95

Answer 11

Amount at cylinder: none

SPHERE

Question 12

Identify the amount (in diopters) and the type (WTR/AGT/Oblique/Irregular)of corneal cylinder indicated by the following K readings.

45.50@40/43.62@130

Answer 12

Amount at cylinder: 1.87

OBLIQUE

Question 13

Identify the amount (in diopters) and the type (WTR/AGT/Oblique/Irregular)of corneal cylinder indicated by the following K readings.

42.75@170/46.62@80

Answer 13

Amount of cylinder: 3.87

IRREGULAR

Question 14

The instrument used to measure the curvature of the corneal cap

Answer 14

Keratometer

Question 15

The first step necessary and taking accurate Keratometer readings is

Answer 15

To focus the eyepiece

Question 16

K’s of 44.75/42.50 x135 indicate which type of corneal astigmatism?

Answer 16

Oblique

Question 17

What amount of cylinder is present in 44.75/42.50x135?

Answer 17

2.25

Question 18

Accepted value for the index of refraction of the pre-corneal tear film is

Answer 18

1.3375

Question 19

The normal range of the Keratometer is

Answer 19

36.00 - 52.00 D

Question 20

How much corneal cylinder is in 42.00@180/43.00@90

Answer 20

1.00D

Question 21

What is the radius of curvature of the flattest K in 42.00@180/43.00@90?

Answer 21

42. 00=8.03mm

337. 5/42 = 8.03mm

Question 22

The instrument that uses a computer to evaluate thousands of points across the cornea to generate a map of the corneal surface is the

Answer 22

Topographer