for OD students by kausar Ali

2. ANISOMETROPIA
 Total refraction of the two eyes is
unequal .
 Difference of 1 D in two eyes cause
a 2 % difference in size of the two
retinal images .

3. 5% size difference / 2.5 D well
tolerated .
2.5 – 4 D individual sensitivity
>4 D not tolerated

4. Alternate vision when one of two eyes is used
at a time .
Occurs when one eye is emmetropic or
moderately hypermetropic and the other myopic .
Patient uses former eye for distance vision and

5. And latter for near vision .
Anisometropia leads to development
of squint .

6. Etiology :
Congenital and developmental
Acquired .
Uniocular Aphakic
Wrong power IOL

7. Trauma
Keratoplasty .
Clinical types :
Simple : one eye is normal other mopic
/hypermatropic /astigmatism .

8. Compound : both eyes myopic/
hypermetropic / astigmatism /
Mixed : one eye myopic / other eye
hypermetropic / astigmatism

9. STATE OF BINOCUAR VISION
If the refractive error difference is 4 diopters ( px
fusional power) .
Uniocular vision : if the defect in one eye is higher
it may be excluded from vision at early stage of life
The more emmetropic eye become amblyopic .

10. Alternate vision: hyperopic / myoic
Diagnosis :
Retinoscopy under cycloplegia
State of vision friend test ..
Worth four dot test .

11. Friend test : ( FIN green Red red )
The patient wears red green goggles and is
seated at a distance of 6 meter from the chart .
Binocular single vision will read friend at once.
Uniocular vision will read either fin or red .

12. Alternate vision will read FIN at one time and Red
other time .
Worth four Dot test:
The W4LT can be performed by examiner by two
distances 33cm and 6cm .

13. The W4LT instrument is composed of a
silver box which has 4 lights inside it . The 4
light are arranged in a diamond formation
with a red light at a top two green light exact
same manner and white light at the bottom .

14. The patient wear red and green
goggles red for right eye and green for
left eye.

16. Se all four light in absence of manifest squint
normal binocular vision .
ARC sees four lights in presence of manifest
squint .
See 2 red lights left eye suppression .

17. See 3 green light right eye suppression .
See 2 red and 3 green alternatively alternate
suppression .
See 5 lights ( 2 red and 3 green ) diplopia .

18.  Treatment :
 Glasses .
 Contact lenses
 Keratoplasty .