All are true about concomitant squint except:
Ans: b (Diplopia usually present) Ref: Khurana, 4th ed, p. 321Squint is a tough topic as far as postgraduate entrance exam is concerned. But there is no way out.Atleast try to learn the difference between concomitant and inconcomitant squint byheart. That will help a lot.Squint:Misalignment of the visual axes of the two eyes is squintType:* Pseudostrabismus or apparent squint* Heterophoria or latent squintHeterotropia or manifest squint|||----- a) Concomitant----- b) InconcomitantApparent squint: Visual axes parallel but eyes seem to have squintPseudo esotropia (app. Convergent) -> e.g., prominent epicanthal foldPseudo exotropia (app divergent )-> e.g., hypertelorismHeterophoria (latent squint)Tendency of eyes to deviate is kept latent by fusion types* Exophoria-tendency to diverge* Esophoria - tendency to converge* Hyperphoria - tendency to deviate upwards* Hypophoria - tendency to deviate downwards* Cyclophoria - tendency to rotate around anteroposterior axisTreatment of heterophoria (decompensated)1. Correct refractive errors2. Orthoptic treatment3. Prescription of prism/ glasses4. Surgical treatmentHeterotropia (manifest squint) - Cover test confirms heterotropiaTypes:1. Concomitant: Amount of deviation in squinting eye constant in all directions of eye2. Incomitant: Amount of deviation varies in different directionsConcomitantIncomitant* Convergent (esotropia)* Divergent (exotropia)* Vertical (hypertropia)* Paralytic* 'A' and 'V' pattern heterotropias* Special ocular motility defects e.g., Duane retraction syndrome,Brown's oblique tendon sheath syndromeTests in paralytic squint* Diplopia charting* Hess screen test* Field of binocular vision* Forced duction testDifferentiating features between concomitant and incomitant squint Incomitant squintConcomitant squintMagnitudeVaries with eye positionSame in all positionDiplopiaPresentNormalOcular movementsRestrictedFullFalse projectionPresentAbsentAbnormal head posturePresentAbsentSecondary deviation> primary deviationEqual to primary deviationTreatment of manifest squint1. Treatment of the cause2. Conservative measures-vit B, steroids, wait and watch policy3. Treatment of diplopia4. Surgical treatmentLaws governing ocular movements:1. Herring's law of equal innervation2. Sherrington's law of reciprocal innervation
Angle of primary deviation is equal to angle of secondary deviation
Diplopia usually present
There is no limitation of movement
Position of head is normal
Strabismus