Lecture 1 - Epidemiology & Classification of Vision Impairment

The International Classification of Diseases 11 (2018) classifies vision impairment into what two groups

distance presenting vision impairment

near presenting vision impairment

In total, (distance and near) it's estimated how many people have a vision impairment world wide

2.2 Billion

How many people in the world have near vision impairment

1.1 Billion

(this is simply because they dont have access to a pair of glasses)

___% of the World's visually impaired live in developing countries, and most are over the age of ___

90%

age fo 60

> ___% of visual impairment is avoidable

>75%

There is an estimated ___ cases of childhood blindness worldwide

1.4 million

List the 5 leading causes of childhood blindness

• Congenital Cataracts (developing countries)

• Optic Atrophy

• Albinism

• Retinopathy of Prematurity (developed countries)

• Genetic Diseases (retinal)

Congenital Cataracts is a leading cause of blindness in (developing/developed) countries, why

developing

they don't have the resources to undergo cataract surgery

Retinopathy of Prematurity is a leading cause of blindness in (developing/developed) countries, why

developed

this kind of retinopathy occurs 2° to the tx of supplemental oxygen used when a baby is born prematurely... underdeveloped countries don't have that therapy and therefore don't have this retinopathy

Almost __% of those with low vision in the US are over the age of 65

90%

Both blindness & visual impairment are projected to increase x___ by the year 2050

x2 (double)

What is the demographic with the current highest prevalence of visually impaired and blind individuals in US

non-hispanic white women

(T/F) "Legal Blindness" is a functional definition

FALSE

it's not a functional definition and doesn't explain very much at all about what a person can and cannot see

(T/F) There is a difference between statutory blindness and qualifying for disability

TRUE

__________ is a definition used by the United States government to determine eligibility for vocational training, rehabilitation, schooling, disability benefits, low vision devices, and tax exemption programs

"Legal Blindness" or Statutory blindness

The ____________ defines legal blindness and requirements for disability based on vision impairment and efficiency, there is a VA and VF definition/cut off

Social Security Act (SSA)

(T/F) Individual states can alter the VA/VF cut offs for what defines Statutory blindness

FALSE

cant change the cut off, but when there is a pt that you cant get an accurate VA or VF reading on... in SOME states you can register that pt if you believe they are functionally legally blind

(non-verbal pt is an example of this)

_____ governments are responsible for the registration and distribution of eligible state benefits

state

(T/F) State registries are always connected to the Registry of Motor Vehicles

FALSE

some states are not

In MA eye care providers are required to report all cases of legal blindness to the Massachusetts Commission for the Blind within ___ days

30 days

Legal Blindness = BCVA of 20/___ or less in the (worse/better) eye

20/200 in the better eye

Legal Blindness = VF of ___° diameter or less at widest diameter in the (worse/better) eye

20° diameter

Your pt is able to identify only 1 letter on the 20/100 line, do they qualify as legally blind

No

pt qualifies if no letters correctly identified on 20/100 line

Your pt is unable to identify any letters on the 20/100 line, do they qualify as legally blind

Yes

pt qualifies if no letters correctly identified on 20/100 line

What VF test is performed to establish if a pt qualifies as legally blind

HFV 30-2 or 24-2

(T/F) When testing vision for legal purposes, eccentric viewing can be used

FALSE

When testing for function, EV can be used.

When testing for legal purposes/legal blindness, central fixation is used

Your patient reads 20/200 before refraction. Assuming they have a full visual field, are they legally blind?

No, you haven't done refractions yet and legal blindness is based on BCVA

Your patient reads 20/200 after refraction. Assuming they have a full visual field, are they legally blind?

Yes, they are worse than 20/200 with their best correction

Your patient reads 20/125 after refraction. Assuming they have a full visual field, are they legally blind?

Yes, they have no read anything on the 20/100 line and therefore are considered legally blind

Your patient 20/100 after refraction while using eccentric viewing. Assuming they have a full visual field, are they legally blind?

Yes, they must be able to read some 20/100 letter with central fixation to not be considered legally blind

Your patient has entering acuity of 20/200, and pinholes to 20/100 but during refraction you can only get them to read 20/125. Are they legally blind?

Yes, pinhole does not count as BCVA

Your patient's BCVA is 20/200 with glasses and 20/80 with contacts, but they have tried learning how to take them out and they just can't do it so they've decided to wear glasses full time. Are they legally blind?

Yes, CL can not be considered BCVA if they cannot wear them

Your patient's BCVA is 20/200 but with a 3x telescope they can read 20/80. Legally blind?

Yes, telescopes cannot be used to determine BCVA

What is the stimulus used when determining VF qualifications of legal blindness

Goldman III4e white stimulus

Your patient reads 20/20 but has 20 degrees of visual field in the right eye and 30 degrees of central field in the left eye. Legally blind?

No, they have a 30° VF in one eye, which is above the 20° minimum

Your patient has 10 degrees of central VF in the right eye and 10 degrees of central VF in the left eye. Legally blind?

Yes, this pt has less than 20° of VF in either eye

What does the "III" mean in the standard Goldmann white III4e stimulus used for VF qualification

test stimulus size

What does the "4e" mean in the standard Goldmann white III4e stimulus used for VF qualification

intensity of the stimulus

Normal temporal VF is ____°

100°

(she has 90+ on her slide)

Normal nasal VF is ____°

60°

Normal superior VF is ____°

60°

Normal inferior VF is ____°

75°

The blind spot is ___° temporally from where the optic nerve leaves the eye

15°

When looking at a HVF print out, each hash mark on the x and y axis corresponds to ____° of visual field

10 degrees

*image slide 44*

When looking at a HVF print out, each point is ____° apart horizontally or vertically from any adjacent point

6 degrees

*image slide 45*

When looking at a HVF print out, any tested point adjacent to an axis is ___° from that axis.

3 degrees

*image slide 45*

When looking at a HVF print out, the four tested points immediately surrounding the point of fixation are each ___° horizontally and vertically from the point of fixation

3 degrees

*image slide 45*

When looking at a HVF print out, dB value of ___ is considered normal

30

When looking at a HVF print out, dB value of ___ is considered low sensitivity and significant field loss

0-20

When looking at a HVF print out, dB value of ___ is considered hypersensitive & the pt is trigger happy

>40

___ dB threshold with Humphrey is equivalent to a 4e intensity on Goldman

10 dB

When assessing HVF for legal blindness, ___dB or (lower/higher) is classified as seeing

10dB or higher

When assessing HVF for legal blindness, ___dB or (lower/higher) is classified as non-seeing

10dB or lower

How is a Pseudoisopter determined

measuring the wides diameter of the VF boarders designating the seeing area from the non-seeing area

diameter must go through the point of fixation and is drawn midway between any 2 adjacent tested points when one threshold is 10 dB or greater and the other threshold is less than 10 dB

*image and examples slide 48-52*

Determining legal blindness from HVF gray scale print outs - examples slide 53-57

go look at them

(T/F) Functional vision = measurable vision

FALSE

functional vision impairment depends on the visual demand

referrals for low vision care are often delayed until visual acuity is severely impaired, long after functional vision has been affected

The goals of low vision management is essentially to maintain ________

quality of life