12 Asimellis Lab Q's Flashcards
A letter on the 20/20 line of the snellen chart subtends an angle (ENTIRE LETTER) of…
1 arcmin 5 10 20 ??
5 arcmin!
Each space is on letter is 1 arcmin
If a patient reads the snellen chart from a distance of 10ft..he can just read the 20/20 line. His VA, in snellen fraction is what?
10/10
20/20
20/10
20/40
20/40
Since he sees 20/20 10ft closer than normal (20 ft; so HALF)
He would see 20/40 at best, 20ft away!
Who first standardized the charts for VA’s at distance and near?
Louise L. SLOAN!
Which chart is used for research? Pick one
Snellen
ETDRS charts
Bailey Lovie chart
Landolt C
Tumbling E
ETDRs(Early treatment of Diabetic retinopathy study) charts
Have same number of optotypes per line, length = width of each letter, progresses down by 0.1 log units
The log of 10 =?
What about log1?
The exponent that 10 must be raised to, to get 10 is..1!
Exponent that 10 must be raised to, to get 1 is…0!
Which value of visual acuity, when expressed in LogMAR units is better?
- 0.30 logMAR
0. 00
1. 00
2. 00 logMAR
-0.30 logMAR! Most negative is best vision
LogMAR VA= 0.1 + LogMAR finest line - 0.02 x (total #of characters read in the last line) true or false?
TRUUU
For standard visual acuity..
Snellen= 20/20
MAR= _ arcmin
LogMAR=.
VAR=100
1arcmin
0.0
For 20/10 vision.. what’s
MAR?
Total optotype angular extent?
Decimal VA?
LogMAR?
- 5 arcmin
- 5 arcmin
2
-0.3
For 20/20vision.. what’s
MAR?
Total optotype angular extent?
Decimal VA?
LogMAR?
1 arcmin
5 arcmin
1.00 (10/10)
0
For 20/40 vision.. what’s
MAR?
Total optotype angular extent?
Decimal VA?
LogMAR?
2 arcmin
10 arcmin
- 5
- 3
For 20/100vision.. what’s
MAR?
Total optotype angular extent?
Decimal VA?
LogMAR?
5 arcmin
25arcmin
- 2
- 7
For 20/200 vision.. what’s
MAR?
Total optotype angular extent?
Decimal VA?
LogMAR?
10 arcmin
50 arcmin
0.1
50
