Lecture 6 - preliminary evaluation

Question 1

what is the normal blink rate?

Answer 1

10-15 per minute

Question 2

why is the lid positioning important to measure/observe?

Answer 2

some lenses are balanced on the eye using lid forces (toric lenses)

Question 3

how do you assess lid tension?

Answer 3

pull upper lid outward - grade resistance (3+ = very tight and -3 = very loose)

Question 4

what is the LIPCOF grading scale?

Answer 4

the lid parallel conjunctival folds - if patient has long term dry eyes, the conjunctival becomes loose

Question 5

what grade on the LIPCOF scale is considered dry eyes?

Answer 5

grades 3 and 4 (1 and 2 = no dry eyes)

Question 6

if the patient has 1 or more folds but are shorter than the tear meniscus height, what is the LIPCOF grade?

Answer 6

grade 1
(if same height = 2 and if higher than meniscus = 3)

Question 7

why can an iris iridectomy be a concern?

Answer 7

it creates a second pupil if lids don’t cover hole

Question 8

what are some invasive techniques to assess tear film?

Answer 8

TBUT, schirmer, phenol red, rose bengal, lissamine green and tear osmolarity test

Question 9

what are some non-invasive techniques to assess tear film?

Answer 9

NITBUT, tear prism/meniscus height, tear viscosity and lipid layer evaluation

Question 10

what is a normal TBUT?

Answer 10

more than 10 sec (abnormal = less than 10 sec)

Question 11

what is a normal schirmer test? how long are strips left on eye?

Answer 11

5 minutes

normal = greater/equal to 10mm (abnormal less than 10mm)

Question 12

what is the phenol red thread test testing?

Answer 12

tear volume (basal) and pH

Question 13

how does the phenol red test for pH?

Answer 13

color changes from yellow - red when pH is 6.6 to 8.2

Question 14

how long is the phenol red test and what is normal?

Answer 14

15 seconds

normal = greater/equal to 20mm (abnormal less than 20mm)

Question 15

what does the rose bengal stain?

Answer 15

dead and devitalized epithelial cells and mucus (mucins and other tear film components block staining)

Question 16

what does Lissamine green stain?

Answer 16

dead and degenerated cells - not healthy epithelial cells

Question 17

what is a dry eye tear osmolarity result?

Answer 17

values > 308 mOsms/L (higher salt concentration in dryness)

Question 18

what is the NITBUT test?

Answer 18

non-invasive TBUT - use diffuse white light and observe mire stability/tears

Question 19

what is a normal tear prism/meniscus height?

Answer 19

0.2-0.4mm (abnormal = less than 0.1mm)

Question 20

what do you look at when assessing the viscosity of tear film?

Answer 20

movement of bits of debris in the tear prism - how rapidly they move in the pre-ocular tear film (POTF)

Question 21

what are you looking at during the lipid layer evaluation?

Answer 21

superficial lipid layers - different interference patterns are formed and each correspond to a lipid layer thickness

Question 22

what is the thickest lipid layer formation? what is the thinnest?

Answer 22

color fringes = thickest
amorphous
flow pattern
meshwork = thinnest

Question 23

what is a normal lower lid position? Upper lid position?

Answer 23

lower lid = -1.0 to +2.0

upper lid = -0.5 to -2.0mm

Question 24

what is a normal tear viscosity?

Answer 24

2-3 = normal (5 = ver viscous and 1 = watery)