amblyopia

Question 1

define amblyopia

Answer 1

reduced acuity in one or both eyes with no pathological cause for the reduced VA

Question 2

How is amblyopia caused?

Answer 2

Caused by abnormal visual development during the critical period or visual development

Question 3

How many people affected?

Answer 3

affects 1% - 4% of the population

Question 4

What type of amblyopias are there

Answer 4

Refractive
Stimulus deprivation
Strabismic

Question 5

What is refractive type of amblyopia

Answer 5

Results from uncorrected refractive error in one or both eye usually anisometropia
e.g R eye only 4 accommodation and L eye no accommodation so the eye becomes lazy for length period of time results into amblyopic eye

Question 6

what is the Importance of good refractive technique?

Answer 6

sloppy refractive techniques you can get away with non amblyopic px but amblyopic patient can give you grieve if the refraction technique is not right.

Question 7

what aspects of refraction technique is important for amblyopes?

Answer 7

• Choice of dioptric interval
• Crossed cyl target
• Crossed cyl power
• Fan and block
• Pinhole disc
• BB ( Binocular Balancing )
• Retinoscopy in strabismic amblyopia

Question 8

what if you give small choice of dioptric interval?

Answer 8

small D intervals such as 0.25D steps will lead to wrong results and waste time. px will see things same not better.

Question 9

What powers DS should amblyopes be givemn

Answer 9

Amblyope patient to be given high powered sphere to begin with depending on patients acuity and then refine results with small powers

Question 10

what is the large then small powered dioptric interval technique called?

Answer 10

Bracketing technique

Question 11

What cross cyl targets used for amblyopes

Answer 11

if px vision in better that 6/12 use concentric rings for x cyls

Question 12

what VA do the concentric rings represent?

Answer 12

Inner ring approx equivalent to 6/6 snellen chart

outer ring approx equivalent to 6/15 snellen chart

Question 13

what can xcyl do with vision?

Answer 13

crossed cylinders can reduce the vision in one or both positions

Question 14

if patienty has VA worse than 6/12 ?

Answer 14

Do not use concentric rings for cross cylinders

Question 15

what cross cylinder powers should you use in amblyopic eye?

Answer 15

use bracket approach

begin with high powered cyl +/- 0.50 and use +/-n 0.25DC only if changes produced are appreciated by the px

Question 16

when do you use more that +/- 0.50DC cylinders?

Answer 16

Use +/- 0.75 or +/- 1.00DC if the vision is severely impaired. refine with small powers if px appreciates it.

Question 17

What Vision is Fan and block equivalent to?

Answer 17

Fan and block is quivalent to 6/15 snellen chart

Question 18

when should you not use fan and block?

Answer 18

do not use fan and block if px vision is worse that 6/12

Question 19

when can you use fan and block?

Answer 19

use fan and block is vision is better that 6/12

Question 20

How does pinhole work in Amblyopes?

Answer 20

Distinguish between poor acuity/vision due to bad refraction or poor acuity/vision due to amblyopia ( or eye disease)

Question 21

what if acuity improves with pinhole?

Answer 21

errors in refraction

Question 22

what if acuity does not improve with pinhole?

Answer 22

unlikely to improve acuity with refraction and has underlying pathology

Question 23

what does pinhole do?

Answer 23

pinhole cuts out parallel rays smaller apeture and makes image clearer and acuity is improved.

Question 24

Which patient can you Balance?

Answer 24

Any patient with good binocular sincle vision and good acuity in each eye

Question 25

which patients can you not balance ?

Answer 25

patients with :
Amblyopic 
squint 
monocular 
VA difference in 3 lines or more 
presbyopes

Question 26

How can you do BB in amblyopes?

Answer 26

Use the Turvilles infinity balance test monocularly.

Question 27

What is TIB test ?

Answer 27

Turville’s infinity balance test

Question 28

How does TIB test work?

Answer 28

place septum infron of the R eye and Leye views
Then place septum on left eye and R eye views
if left eye was amblyopic can see 6/12 so equally clear

Question 29

How do you do retinsocopy in strabismic eye ?

Answer 29

it is difficult to work on- axis when retinoscopy is carried out on a squinting eye.
occlude fixing eye

Question 30

what is the problem in fixing the eye for the retinsocopy in strabismic eye - distance fixation ?

Answer 30

optometrist head gets in the way of the target

Question 31

when can you do retinsocopy in strabismic eye- distance fixation?

Answer 31

if the angle beta < angle alpha

Question 32

when do you do retinoscopy in strabismus distance fixation?

Answer 32

worth doing if squint is greater than 10 prism Dioptre

Question 33

how do you do retinoscopy near fixation in strabismus?

Answer 33

position ret where two axes meet, but where is this? location may change during retinsoscopy

Question 34

why should you not occlude during near fixation?

Answer 34

not recommended as accommodation is vary unstable

Question 35

What do you use in retinsocopy in strabismus?

Answer 35

Use a cyloplegic drug

occlude the fixing eye and patient can directly fixate the ret light

Question 36

why do you use cycloplegic drug?

Answer 36

partially paralyse acoomodation

Question 37

who is refraction for amblyopes good for.

Answer 37

Good for and acceptable for children but cause problems for others.