Geometry of VA Flashcards
(18 cards)
What is the aim of the course on the Geometry of Visual Acuity?
To introduce terms necessary for studying the behaviour of light, start using calculators, provide basics of Snellen acuity, and introduce logarithm to base 10.
What learning outcome involves manipulation of time units?
Able to manipulate minutes and seconds using your calculator.
What is 20/20 vision equivalent to in the context of visual acuity?
6/6 vision.
What does a whole 6/6 E subtend at the nodal point of the eye?
5 minutes of arc.
What trigonometric function can be used to calculate the height of an optotype?
tan.
What is the Minimum Angle of Resolution (MAR)?
The smallest visual angle that can be resolved, usually measured in minutes of arc.
What is the angular subtense of the Unit Length for a 6/6 optotype?
1 minute.
What is spatial frequency in the context of visual acuity?
The number of cycles (black and white lines) per degree.
How many cycles per degree correspond to 6/6 vision?
30 cycles per degree.
What is the reverse function of a logarithm?
Exponentiation.
What is Log10 100000?
5.
What does LogMAR stand for?
Logarithm of the Minimum Angle of Resolution.
When was LogMAR suggested and by whom?
In 1976 by Ian Bailey and Jan Lovie.
What is the LogMAR equivalent for a Snellen 6/6?
0.0.
True or False: Orthoptists primarily use Snellen measures.
False.
Fill in the blank: 20/20 vision is equivalent to 6/6 vision, which is also equivalent to _______.
MAR 1.
What does the British Standard BS-4274-1 (2003) pertain to?
Visual acuity test types.
What is the connection between Snellen measures and LogMAR?
Both are measures of visual acuity, but LogMAR is preferred by orthoptists.
