Anisometropia is a condition where there is a difference in refractive power between the two eyes. It occurs when the total refraction of the two eyes is unequal. A difference of 1 diopter (D) causes a 2% difference in the size of the retinal images between the eyes, and differences up to 5% are generally well tolerated. Anisometropia can be congenital or acquired later in life. It is diagnosed via eye exams and can cause symptoms like eye strain, headaches, and impaired depth perception. Treatment options depend on the degree of anisometropia and include glasses, contact lenses, refractive surgery, or intraocular lens implantation.

1. ANISOMETROPIA
BY JEEVANA

2. The name is from four Greek
components :
an means not
iso means same
metr means measure
ops means eye

3. • The optical state with equal refraction is
isometropia
• When the total refraction of two eyes is
unequal it is called anisometropia
• Small degree of anisometropia is of no
concern
• A difference of 1D in two eyes causes a 2%
difference in size of two retinal images
• A difference of upto 5% in retinal images
of two eyes is well tolerated

4. • In other words , an anisometropia upto
2.5 is well tolerated and that between 2.5
and 4 can be tolerated depending on
individual sensitivity
• However if it is more than 4D , it is not
tolerated.
• Each eye can be nearsighted (myopia)
farsighted (hyperopia) or a combination of
both its called antimetropia
• A difference in power of 2D or more is the
accepted threshold to label it as
anisometropia

5. • 6% subjects aged 6 to 18 have
anisometropia
• In certain types of anisometropia , the
visual cortex of brain will not use both
eyes together (binocular vision) , and will
instead suppress the central vision of one
of the eyes. If this occurs often enough
during first 10 years of life while the visual
cortex isdeveloping , it can result in
amblyopia ,a condition where even when
correcting the refractive errror properly ,
the person is still not correctable to 20/20

7. ETIOLOGY :
• CONGENITAL AND DEVELOPMENTAL
ANISOMETROPIA occurs due to
differential growth of the two eyeballs
(uneven growth in both eyes and inborn
defects in the eye)
• ACQUIRED ANISOMETROPIA due to
asymmetric age change uniocular aphakia
ofter removal of cataractous lens or due to
implantation of IOL of wrong power

8. CLINICAL TYPES :
• SIMPLE ANISOMETROPIA : one eye is normal
(emmetropic) and the other eye myopic or
hypermetropic .
• COMPOUND ANISOMETROPIA : both eyes are
hypermetropic or both eyes are myopic , but one
eye is having higher refractive error than the
other
• MIXED ANISOMETROPIA : one eye is myopic
and other eye is hypermetropic (antimetropia)

9. • SIMPLE ASTIGMATIC ANISOMETROPIA :
one eye normal and the other has either simple
myopic or hypermetropic astigmatism
• COMPOUND ASTIGMATIC ANISOMETROPIA:
both eyes are astigmatic but of unequal degree

11. SYMPTOMS
• Eye strain
• Headaches
• Sensitivity to light
• Complexity in reading
• Nausea and fainting
• Sheer tiredness
• Depth perception impaired
• Diplopia
• Amblyopia
• strabismus

12. STATUS OF BINOCULAR VISION IN
ANISOMETROPIA :
• BINOCULAR SINGLE VISION : present in
small degree of anisometropia
• UNIOCULAR VISION : when refractive
error in one eye is of high degree , that eye
is suppressed and develops anisometropic
amblyopia.
• ALTERNATE VISION : when one eye is
hypermetropic (for distant vision) and
other eye myopic (for near)

13. DIAGNOSIS
• If a person has anisometropia it is usually
detected or diagnosed when the child has a
vision examination
• If it happens in an older person they may notoice
that their vision is blurry and go in for
examination
• By the symptoms
• Usually it is made after retinoscopic or
autorefractometry in patients with defective
vision

14. TREATMENT:
• SPECTACLES : the corrective spectacles can be
tolerated upto a maximum difference of 4D
• CONTACT LENSES for higher degrees of
anisometropia
• ANISEIKONIC GLASSES available but results
are disappointing

16. • INTRAOCULAR LENS IMPLANTATION
for uniocular aphakia
• REFRACTIVE CORNEAL SURGERY for
unilateral high myopia , astigmatism ,
hypermetropia
• PHAKIC REFRACTIVE LENSES (PRL)
AND REFRACTIVE LENS EXCHANGE
(RLE) quite useful in very high degree
anisometropia