1.1 Why measure vision

Question 1

Key words..

• Ologists
• Graphers
• Ists
• Metrists

Answer 1

• “-ologists” - study a specific subject e.g. geologist
From the greek word logia meaning speaking
• “-graphers” - people concerned with a subject inlcuding writing, recording or drawing about it e.g. radiographer
From the greek graphos meaning something written or drawn
• “-ists” - people that do something specific e.g. cellist
Various roots - a suffix that means a person who practices something
• “-metrists” measure something specific e.g. OPTOMETRIST
From the Greek metron meaning measure or rule

Question 2

What is fundamental to optometry

Answer 2

• The ability to measure things quantitative measurements

- Optometrists measure vision and determine refractive error, and detection and referal of eye disease

Question 3

What does “ opto-“ mean

Answer 3

• Is derived from the greek optikos meaning “ of seeing “
• So optoms MEASURE sight and a number of other features related to it
• Optoms used to be called opthalmic opticians. The legislative framework for all optoms is the Opticians Act ( 1989 )

Question 4

What is vision

Answer 4

• Perception of differences in the external world resulting from stimulation of retina by light.
• Perception of external world in relation to retina
• Can include light changes of the objects we are perceiving, colour, shape, position etc

Question 5

Types of vision:

Answer 5

• Binocular
• Distance
• Double
• Blurred
• Photopic
. Spatial and more

Question 6

Historical note - what was of interest, what happened:

Answer 6

• Interest from ancient times in ability to see detail e.g. double stars - 2 stars that are very close together
• Jaeger ( Vienna ) 1800s produced reading samples ( charts you have infront of you as if you were reading a book ) that were very popular but not standardised
• Donders at same time , working on refraction and accommodation, asked Snellen to produce a measurement tool i.e a chart to test vision
• It was Donders’ original idea but he rarely gets a mention ( he took the idea to Snellen to try and solve the problem )

Question 7

What is refraction

Answer 7

How light is bent and focused in eye

Question 8

What is accommodation

Answer 8

Ability of the eye to focus in near

Question 9

What did Herman Snellen ( 1834 - 1908 ) do:

Answer 9

• Professor of Opthamology at Utrecht, netherlands
• Work on astigmatism, optical calculations, glaucoma ( disease of optic nerve ) , diseases of the retina and connective tissue
  “Optoptypes” first invented in 1843 ( predate snellen chart
  Snellen chart - originated in 1862 = used for testing distance vision

Question 10

What are optotypes and when were they invented

Answer 10

The characters, letters or symbols used for testing vision - test types
Invented in 1843
Different styles of lettering can be used

Question 11

What were Snellen’s innovations

Answer 11

1. Snellen desgined special characters - “optoptypes”, the letters on the original snellen chart are not a standard font that was available at a time. He specifically designed the font for the purpose of his test chart
2. Arranged optotypes in a “letter chart “ to test distance vision ( letters decrease in size from top to bottom and different no. letters on each line )
3. Defined a standard for comparison - the “ standard observer “

Question 12

What are other names for snellen chart

Answer 12

Letter charts

Test chart

Question 13

What is Snellen chart and when was it bought about

Answer 13

The first systematically designed letter chart to test distance vision
1862

Question 14

Why is vision assessed

Answer 14

• To allow us to quantify what people can and can’t see
• Because of changes in vision in health and disease = important to monitor vision
• Occupational reasons - strict vision requirements for pilots and train drivers = visual requirements for some professions
• Salutatory - registrato as sight impaired or severely sight impaired requires vision assessment