The document discusses the diagnostic evaluation process for strabismus. It covers the classification of strabismus, including pseudostrabismus and true strabismus. It also describes tests used to evaluate visual acuity, sensory function, motor function, and stereopsis. These include cover tests, versions, ductions, and specialized tests like Hirschberg's test, Krimsky test, and Bruckner test. The goal of the evaluation is to accurately diagnose the type of strabismus and measure the ocular misalignment.

1. DIAGNOSTIC EVALUATION FOR STRABISMUS Ms. JayaRajini Vasanth Mphil, B.S (opt) Assistant Professor – Optometry Ophthalmology Department Sri Ramachandra University

2. Classification of strabismus Pseudostrabismus (false or apparent squint). B. True strabismus: 1. Latent squint (heterophoria). 2. Manifest squint (heterotropia): - non- paralytic (concomitant). - paralytic (non- concomitant).

3. Axes of the eye Visual axis: Line passes from the fovea to the point of fixation (object of regard). The normal visual axes (from both eyes) intersects at the point of fixation. Optical axis: It is the line passing through the centre of the cornea and meets the retina on the nasal side of the fovea Fixation axis: It is the line joining the fixation point and the centre of rotation

4. Angle kappa is the angle between visual (0ptical) axis and the anatomical (pupillary) axis. - As the fovea lies just temporal to the anatomical axis, a light shown into the cornea will cause reflex (on the visual axis) just nasal to the center of the cornea in both eyes (+ve angle kappa = 5°).

5. In high myopia the, the fovea lies nasal to the optical axis. So, the corneal reflex lies temporal to the center of the cornea simulating esotropia. Negative angle kappa (myopia) leads to pseudo-esotropia. Large positive angle kappa (hypermetropia) leads to pseudo-exotropia.

6. Pseudostrabismus In young infants, strabismus must be differentiated from the more common pseudostrabismus Pseudoesotropia as a result of a broad bridge of the nose. This is not a real eye crossing

7. Pseudo-deviations Pseudo-esotropia Pseudo-exotropia Epicanthic folds Short interpupillary distance Negative angle kappa Wide interpupillary distance Positive angle kappa

8. HISTORY Age of onset of deviation Is the deviation constant or intermittent? Is the deviation present for distance, near or both? Is it unilateral or alternating? Is it present only when the patient is inattentive or fatigued? Is it associated with trauma or physical stress? Old photographs Birth history Is there a family history of strabismus?. Are there any other medical problems? Headaches Is there a history of toxin or medication exposure?

9. VISUAL ACUITY Recognition acuity : Lea symbols, HOTV, Snellen Chart Detection acuity : Stycar Ball test Resolution acuity : Lea Paddles

10. SENSORY EVALUATION Simultaneous macular perception Worth four dot test Stereopsis

11. Tests for sensory anomalies Worth four-dot test a - Prior to use of glasses b - Normal c - Left suppression/ amblyopia Bagolini striated glasses a - Normal or ARC b- Diplopia c - Suppression d - Right suppression/ amblyopia e - Diplopia d - Small suppression scotoma

12. Tests for Stereopsis Tests on stereopsis can be based on two principles- 1.Using targets which lie in two planes, but are so constructed that they stimulate disparate retinal elements and give a three dimensional effect, for example: Circular perspective diagram such as the concentric rings Titmus fly test, TNO test, Random dot stereograms, Polaroid test Langs stereo test Stereoscopic targets presented haploscopically in major amblyoscope 2.Using 3 dimensional targets (e.g. Lang’s two pencil test).

13. Qualitative tests for Stereopsis : Lang’s 2 pencil test Synoptophore Quantitative tests for Stereopsis: Random dot test TNO Test Lang’s stereo test

14. Tests for stereopsis Titmus Red-green spectacles TNO random dot test ‘ Hidden’ shapes seen Polaroid spectacles Figures seen in 3-D Lang No spectacles Frisby ‘ Hidden’ circle seen No spectacles Shapes seen

15. MOTOR EVALUATION Extra ocular muscles Cover test Corneal reflex test – Hirschberg Krimsky Bruckner Dissimilar image test – Maddox rod

16. Evaluation of Motility Two principle methods of evaluating ocular motility are: 1 . Observation of ocular ductions, which are the actual monocular movements of the eye. 2 . Observation of binocular ocular alignment, using cover/uncover and alternate cover testing.

17. Monocular eye movements A- elevation B- depression C- adbuction d- adduction E–extortion F- intortion

18. Ocular movement examination

21. Right esotropia ( RET ) Right exotropia ( RXT ) Right hypertropia ( RHT )right hypotropia Left esotropia ( LET ) Left exotropia ( LXT ) Left hypertropia ( LHT )left hypotropia Alternating esotropia ( ALT ET ) Alternating exotropia ( ALT XT )

22. E esophoria X exophoria RH right hyperphoria LH left hyperphoria E(T) intermittent esotropia X(T) intermittent exotropia RH(T) intermittent right hypertropia LH(T) intermittent left hypertropia

23. Cover test detects heterotropia Uncover test detects heterophoria Alternate cover test detects total deviation Prism cover test measures total deviation

24. Motility tests Tests versions and ductions Grades under/overaction Left inferior oblique overaction Left lateral rectus underaction

25. Hirschberg‘s test Amount of deviation: note location of corneal light reflex 1 mm = 7 ° or 15 Δ Reflex at border of pupil = 15 ° Reflex at limbus = 45 °

26. Hirschberg’s Test Used as an initial screen for strabismus How it works: Stand several feet in front of child with penlight shining at eyes Light reflection will be at the same point in each eye Normal Exotropia Esotropia

28. Krimsky Test

29. Modified Krimsky test Asymmetric positions of the corneal reflex in the pupils of each eye are indicative of strabismus, which may be measured by placing a prism before the fixating eye until the reflection is similarly positioned in both eyes Base out prism for esotropia and Base in prism for exotropia This is the direct reading of the squint angle.

30. Bruckner Test Is performed by using direct ophthalmoscope to obtain a red reflex simultaneously in both eyes. If there is strabismus , the deviated eye will have a lighter and brighter reflex than the fixing eye. Media opacities, Refractive errors, Strabismus

31. Dissimilar image tests Maddox wing Maddox rod Dissociates eyes for near fixation (1/3 m) Measures heterophoria White spot converted into red streak Cannot differentiate tropia from phoria

32. Measurements of ocular misalignment Measurement of squints/misalignments Synoptophore - picture test Measure - misalignments, sensory and motor fusion and stereopsis Predict BV post-surgery Measure misalignments 9 positions of gaze

33. Prism Cover Test Measure squint/misalignment Single prism/prism bar Primary position or in all positions of gaze

34. Thank You