1 Tear Film Optics

Question 1

Considering the anterior chamber of the eye, what part:

1) protects cornea by providing a barrier against water, larger molecules and toxic substances
2) consists mainly of randomly arranged collagen fibrils
3) comprises 90% of corneal thickness, over 200 collagen lamellae. Collagen fibrils run parallel to each other and then successive lamellae run across the cornea at angles to each other
4) basement membrane of endothelial cells
5) single layer formed as honeycomb structure, maintains 78% hydration.
6) located between the stroma and descemet’s membrane, type 1 collagen

Answer 1

Epithelium 
Bowman's membrane 
Stroma 
Descement's membrane 
Endothelium 
Dua's layer

Question 2

What is the most anterior refractive surface of the eye? Made of two thin surfaces of almost equal radii. Composed of oily, aqueous, and mucous layers with an optical power of 48.35D. Essential for clear vision and reduces transmission when the tear film runs dries out.

Answer 2

Pre-corneal tear film

Question 3

Tear film stability is measured by its ‘lack of stability’, TF refers to ‘_______ rate’. Instability of TF occurs due to the depletion of aqueous component of tears

Answer 3

Evaporation

Question 4

Due to the change in ________ _____ at the air-tear interface is far greater than at any other optical interface in the eye, irregularities in the ______ surface of the tears have the potential to significantly degrade the optical quality of the eye.

Answer 4

Refractive index

Anterior

Question 5

What is a disorder of the tear film due to tear deficiency or excessive tear evaporation which causes damage to the interpalpebral ocular surface and associated with symptoms of ocular discomfort?

Answer 5

Dry Eye

This is the global definition

Question 6

Dry eye is a multifactorial disease, symptoms of _______, visual _________, and tear film ________ with potential damage to the ocular surface.

Drying of the eye has MAJOR impact on the quality of optical system of the eye.

HOA like spherical and coma, are about . times greater in dry eyes than in healthy eyes

Answer 6

Discomfort

Disturbance

Instability

2.5

Question 7

The contact lens sits __ the tear film. It’s about 10 times thicker than the aqueous layer. It’s dependent both on the lens ______ and on the individuals tear chemistry. The lens can ______ levels of specific components in the tear film by sorption. The lens can _______ the biochemical generation of additional components.

Answer 7

IN

Material

Deplete

Stimulate

Question 8

The microvilli that extend into the precorneal tear film has a wavelength thats comparable to that of ____ light and will increase scatter

Answer 8

Green

Question 9

Does tear film stability decrease with age significantly?

Who has significantly longer TBUT, women or men? (Tear break of time)

Ocular surgery can impact the stability of Tear film stability, as well as local _______. Can also be influenced by external environments like temperature, humidity, AC, pollution etc. smoking and alcohol as well as computer use can affect this too.

Answer 9

YES

Men

Irregularities