This document discusses anisometropia, which is an unequal refractive error between the two eyes. A difference of 1 diopter causes a 2% difference in retinal image size, and a difference of 2.5-4 diopters is generally tolerated, whereas over 4 diopters is not. Anisometropia can lead to amblyopia, alternating vision, or strabismus. It has congenital, developmental, and acquired causes. Diagnosis involves retinoscopy and vision tests like the Worth Four Dot test. Treatment options include glasses, contact lenses, and keratoplasty.

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 .