Evaluating Soft Lenses

Question 1

Soft CL history

Answer 1

• First soft hydrogel est. 1965 by Dr. Otto Wichterle and Dr. Draoslav Lim
• HEMA was originally used for treatment of corneal pathology as bandage CL
• In 1980’s silicone hydrogel was developed increasing O2 permeability, good comfort

Question 2

Base curve

Answer 2

Radius of curvature, back surface of lens where it meets eye
Provided by keratometer

Question 3

Power

Answer 3

Located in the optical zone, center of lens

Question 4

Diameter

Answer 4

Derived from HVID

Question 5

Before Evaluating Soft Lenses

Answer 5

Allow 2-5 minutes for lens to stabilize
- Check VA
- Perform OR
- VA should remain stable before during and after blinking

Question 6

What is over refraction?

Answer 6

Trying to get as close to 20/20 by adding/subtracting 0.25D
If patient is already 20/20 there is no need for OR

Question 7

Evaluating CLs

Answer 7

1. Check movement, 0.5-1mm during blinks
   Movement is evaluated in straight, upgaze, left and right
2. Check centration, should cover out to limbal area

Question 8

Tight fitting lens

Answer 8

1. Fluctuating VA, clearest after blink
2. Edema can cause foggy FA and halos
3. Conjunctival dragging and indentation
4. Central bubbles with push up

Question 9

Loose fitting lens

Answer 9

1. Edge lift
2. Poor comfort due to excessive movement
3. Fluctuation in VA, blurs right after blink
4. Peripheral bubbles with push up

Question 10

Decentered lens

Answer 10

1. Corneal exposure and dryness
2. Symptoms of FB sensation

Question 11

Push up test

Answer 11

Technique used to evaluate movement of CL, straight gaze and upgaze
AKA Passive movement test