7.2 Contact Lenses

Question 1

What is the difference in Ks of the cornea?

Answer 1

Astigmatism

Question 2

What if Ks are the same on a cornea?

Answer 2

No cylinder/ no astigmatism, spherical eye

Question 3

How do you measure vertex distance?

Answer 3

Back of spectacle lens to front apex of eye

Question 4

What power above + or - changes the CL rx compared to spectacle RX?

Answer 4

Greater than or equal t +4.00 or -4.00

Question 5

Both plus and minus CLs go more _____ in the CL RX compared to spectacles RX?

Answer 5

Plus (+5.00 goes to +5.50 but -5.00 goes to-4.50)

Question 6

Extended wear CL means

Answer 6

Approved to sleep in

Question 7

DK is

Answer 7

Oxygen permeability of a CL. How much oxygen gets through the CL to the cornea/ how much oxygen penetrates the CL

Question 8

A higher DK means : less oxygen through to cornea or more oxygen through to cornea

Answer 8

High DK= more oxygen permeability or more oxygen penetrating cl to reach cornea

Question 9

Gas permeable vs PMMA rigid lenses give more oxygen to cornea?

Answer 9

Gas permeable is higher oxygen permeability. PMMA is Poor (old material)

Question 10

Does soft or rigid gas permeable lenses have higher DK?

Answer 10

Think how thin the soft CL is, soft CL has the highest DK

Question 11

Rank in order of highest to lowest DK? PMMA, gas perm, and soft CL

Answer 11

Highest DK: Soft CL—> medium DK: Gas Perm—> low DK: PMMA

Question 12

True or false. Enzyme cleaners are an everyday cleaner for hard lenses?

Answer 12

False. Enzyme cleaners are deep cleans (once or twice a mont)

Question 13

Name new corneal vessels made from corneal ischemia (not enough oxygen from CL overwear)

Answer 13

neovascularization (neo)

Question 14

Name corneal fluid pockets that make haloes on lights and blurred vision

Answer 14

Edema

Question 15

Name the big bumps found under the upper lid with CL allergy with itchiness

Answer 15

Giant papillary conjunctivitis