Anisometropia and Aniseikonia Flashcards
A condition in which the refractive status of one eye differs from that the other.
Anisometropia
A form of anisometropia in which one eye is myopic and the other hyperopic.
Antimetropia
The condition in which the two eyes have unequal refractive power. One eye may be myopic (nearsighted) and the other hyperopic (farsighted) or one eye may be markedly stronger than the other.
ANISOMETROPIA or ASYMMETROPIA
this occurs because of differential growth of the eyeball of both eyes. It is hereditary in origin.
Congenital Anisometropia
created by trauma, pathology or the results of systemic changes.
Acquired Anisometropia
It is a condition in which the refractive power of the two eyes is unequal.
Absolute anisometropia
It is that type of refractive anomaly in which although the total refraction of the two eyes is equal, the component elements in each show relatively large differences. In other words, the total refraction of the two eyes can be equal, but the axial length may be different.
Relative anisometropia
Type of Absolute Anisometropia where one eye is normal and the other is either hypermetropic or myopic.
Simple Absolute Anisometropia
Type of Absolute Anisometropia where both eyes are ametropic either hyperopic or myopic, but one eye has a higher refractive error.
Compound Absolute Anisometropia
Type of Absolute Anisometropia where both eyes are ametropic either hyperopic or myopic, but one eye has a higher refractive error.
Compound Absolute Anisometropia
In this both eyes are ametropic. One eye is hyperopic and the other is myopic. This is called antimetropia.
Mixed Absolute Anisometropia
when one eye is normal and the other has either myopic or hyperopic astigmatism.
Simple Astigmatic Anisometropia
when both eyes are astigmatic but of unequal degree.
Compound Astigmatic Anisometropia
If the anisometropia is high and the eyes have a good visual acuity, the patient gets into the habit of using the hypermetropic eye for distance and the myopic eye for near vision.
Alternating Vision
In small degrees of anisometropia , this occurs. If there is a difference of more than 5D between the two eyes, the patient loses binocularity.
binocular vision
If the defect in one eye is high and if its visual acuity is not good, the eye can be excluded altogether from vision and the eye becomes amblyopic.
Amblyopia
A concomitant convergent squint occurs in children with the eye having the defect becoming convergent.
Strabismus
It is a serious concern in newborns and young children because it can lead to amblyopia (impaired vision in one eye).
Anisometropia
This is when a person has double vision
Diplopia
It is a clinical test mainly used for assessing a patient’s degree of “binocular vision” and “binocular single vision”.
Worth-4-Light test
Tests for amblyopia
LEA Vision Test System
Test for suppression
Worth-4-dot test
A red reflex is when light is transmitted through the transparent portions of the eye and reflects off the retina, creating a reddish orange reflection in the eyes.
iScreen Vision
The various modes of optical treatment and management are:
Spectacles
Contact lenses
The corrective spectacles can be tolerated up to maximum difference of 4D. Higher than that, diplopia may occur.
Spectacles
advised for higher degrees of anisometropia.
Contact Lens
for uniocular aphakia
IOL implantation
for unilateral high myopia, astigmatism, and hypermetropia
Refractive corneal surgery
It is a binocular condition, so the image in one eye is perceived as different in size compared to the image in the other eye.
Aniseikonia
He commented upon the probability of unequal image sizes.
Donders
Discussed the possibility (1903)
C.Hess
Designed iseikonic lenses for aniseikonia
Von Rohr
Condition in which ocular images are unequal in size and shape
Aniseikonia
Lenses which correct aniseikonia and include also the correction of refractive error.
Iseikonic Lenses
It is when eyes are gazing in a certain direction
and images are different in size
Static Aniseikonia
When eyes have to rotate a different amount to gaze at the same point in space
Dynamic Aniseikonia
The size of one ocular image is symmetrically larger that the other.
Overall Symmetrical
the size of one ocular image is symmetrically larger that the other in one meridian only; Axis 90, Axis 180, Axis oblique
Meridional Symmetrical
combination of overall and meridional is manifested.
Compound Symmetrical
Image distortion increases progressively in both directions
Pincushion
Image distortion decreases progressively in both directions
Barrel
Image difference increases progressively in one direction
Prismatic
Image size remains the same but there occurs an oblique distortion of shape
Oblique
Based on binocular space perception
SPACE EIKONOMETRIC METHOD
Based on directly comparing perceived image sizes between the two eyes
DIRECT COMPARISON METHOD
instrumentformeasuringaniseikonia
Space Eikonometer
uses as a target a cross with a small white disc at the center of a black square at its intersection
direct comparison (or standard eikonometer)
3 commercially available direct comparison tests
- New Aniseikonia Test (Awaya Test)
- Basic Aniseikonia Test (version 1)
- Aniseikonia Inspector (version 3)
The Awaya test for Aniseikonia provides amanual methodto detect and calibrate the Aniseikonic condition.
New Aniseikonia Test
it is an easy-to-useWindowssoftware program to test the aniseikonia of a patient. It uses of red-green glasses
Basic Aniseikonia Test (version 1)
is a Windows software program for the clinical management of aniseikonia. It contains:
an advanced aniseikonic test
a design tool to calculate corecting prescriptions (aniseikonia and anisophoria corrections)
Aniseikonia Inspector (version 3)
The patient’s task is to simply identify for each presentation which comparison target is perceived as
larger
Symptoms:
Headache Asthenopia (fatigue, burning, tearing, pain, pulling, etc.) Photophobia Reading difficulty Nausea
Especially with anisometropiait has been shown that this solution (but not always) give less aniseikonia than regular spectacle lenses.
Optical solution 1: Contact Lenses only
This is the classic aniseikonia correction. Optical magnification changes are induced by changing the shape of the spectacle lenses (curvature, thickness) and/or the distance of the lenses to the eyes.
Optical Solution 2: Glasses only, good VA
Altering the refractive power of one of the spectacle lenses.
As a consequence the image is blurred in one eye, reducing the effectiveVAin that eye.
Optical solution 3: Glasses only, compromised VA
This solution is similar to solution 3, but now one contact lens is added to restore the compromised visual acuity.
Optical Solution 4: Contact-Glasses Combination
If an optical correction is not possible or does not provide enough correction, a __ may still be tried
partial occlusion
Instead of occluding part of the visual field, another approach could be to occlude the whole visual field, but with a partial ____
transparent foil.
