STRABISMUS EXAMINATION.pptx.............

Eye Movements Examination
Examination Structure
Sit on the right of the patient, your eyes and the patient’s eyes should be at the same level
Speak whilst examining
Ask children their age
Look around the room for clues – spectacles, parents (for inherited syndromes)
1. Visual Acuity (Best Corrected)
The worse eye is usually the affected one (may be amblyopic)

2. Spectacles
It is easiest to estimate the script of spectacles by comparing the image of a line viewed through the lens and just around it. A distance line such as a doorway is perfect for this purpose.

Hand Neutralise

Minus lens → “With” movement
Plus lens → “Against” movement
Astigmatism

Ground in Prism

The image of the line through the lens has a fixed deviation away from the image of the line just around it. This cannot be compensated by moving the lens. The apex of the prism points towards the deviation.

Fresnel Prism

Method for easy check: turn spectacles side-on
BO (CNVI palsy), BD (CNIV palsy on affected eye)

3. Inspection
Have the patient fixate on a distant target- choose one line above their visual acuity
Only comment on a strabismus if it is obvious (say “there appears to be an exo or eso deviation” in case the patient has a dragged macula and there is no tropia)
1. Abnormal Head Posture (AHP)
Ask patient to “Please sit up straight” and stand back to inspect
Face turn? In direction of action of paretic muscle
Chin up / down? Up in elevator paresis, Down in depressor paresis
Correct any AHP before cover tests (check for neck pathology)
2. ± Corneal Light Reflexes (Hirschberg)
Shine a pen torch into the patient’s eyes and inspect the corneal reflexes. In patients with straight eyes, they should be symmetrical and lie over the same point on the cornea. In patients with strabismus, the corneal reflex of the fixing eye will lie centrally within the pupil, and the other will be displaced (1mm of corneal decentration = 15 Δ strabismus, Pupil margin = 30 Δ, Limbus = 90 Δ). Be aware that tropias can only be definitively diagnosed with cover testing. The Hirschberg test becomes more important when vision is poor (e.g. < 6 / 60 in either eye) and cover-testing is not possible.

3. Ptosis (CNIII palsy)
4. Pupils (Anisocoria) (CNIII palsy)
5. Globe Position
Proptosis (axial vs. non-axial)

6. Other
Nystagmus, facial asymmetry, hearing aids, scars (conjunctiva- squint surgery)

7. Ask Yourself
“Could this be TED?”- proptosis, chemosis, injection, lid retraction

4. Cover-Testing
Ensure the patient can fixate “Tell me if I block your view”
If VA <6 / 60 can’t do cover! → Perform Hirschberg (corneal light reflexes) and / or Krimsky (corneal light reflexes through prism placed over the fixing eye) tests.
The patient should wear their distance (& near) spectacles (unless they have prisms!)
This helps the patient if they can’t fixate on a target uncorrected
It is crucial in accommodative esotropia to test with and without spectacles
Cover for tropia (manifest)
Uncover for phoria (latent)

1. STRABISMUS BY BABLI SHARMA B.OPTOM , M.OPTOM

2. Eye Movements Examination Examination Outline Visual acuity (best corrected) Spectacles Inspection Abnormal Head Posture (AHP ) ± Hirschberg Ptosis ? Anisocoria ? Cover-Testing Ocular Rotations ± Saccades (Horizontal ± Vertical ) Visual acuity Abnormal Head Posture (AHP) Hirschberg Ptosis

3. Examination Structure Sit on the right of the patient, your eyes and the patient’s eyes should be at the same level Speak whilst examining Ask children their age Look around the room for clues – spectacles, parents (for inherited syndromes)

4. 1.Visual Acuity (Best Corrected) W orse eye is usually the affected one (may be amblyopic) 2.Spectacles Hand Neutralise Minus lens → “With” movement Plus lens → “Against” movement Astigmatism Fresnel Prism Method for easy check: turn spectacles side-on BO (CNVI palsy), BD (CNIV palsy on affected eye) Fresnel Prism

5.   3. Inspection Have the patient fixate on a distant target Choose one line above their visual acuity Only comment on a strabismus if it is obvious (there appears to be an exo or eso deviation) Or there is no tropia 1. Abnormal Head Posture (AHP) Ask patient to “Please sit up straight” and stand back to inspect Face turn? In direction of action of paretic muscle Chin up / down? Up in elevator paresis, Down in depressor paresis Correct any AHP before cover tests (check for neck pathology) Abnormal Head Posture

6. 2 .± Corneal Light Reflexes (Hirschberg ) Shine a pen torch into the patient’s eyes and inspect the corneal reflexes. patients with straight eyes, they should be symmetrical and lie over the same point on the cornea. In patients with strabismus, the corneal reflex of the fixing eye will lie centrally within the pupil, and the other will be displaced (1mm of corneal decentration = 15 Δ strabismus, Pupil margin = 30 Δ, Limbus = 90 Δ). Be aware that tropias can only be definitively diagnosed with cover testing. Hirschberg test becomes more important when vision is poor (e.g. < 6 / 60 in either eye) and cover-testing is not possible. Corneal Light Reflexes (Hirschberg

7. 3. Ptosis (CNIII palsy) 4. Pupils ( Anisocoria ) (CNIII palsy) 5. Globe Position Proptosis (axial vs. non-axial) 6. Other Nystagmus , facial asymmetry, hearing aids, scars (conjunctiva- squint surgery) Ptosis (CNIII palsy ) Proptosis

8. 4.COVER TESTING Ensure the patient can fixate “Tell me if I block your view” If VA <6 / 60 can’t do cover!  → Perform Hirschberg (corneal light reflexes) and / or Krimsky (corneal light reflexes through prism placed over the fixing eye) tests. The patient should wear their distance (& near) spectacles (unless they have prisms!) This helps the patient if they can’t fixate on a target uncorrected It is crucial in accommodative esotropia to test with and without spectacles

9. Cover for tropia (manifest) Uncover for phoria ( latent ) Perform cover, uncover tests  slowly   H old the cover in place during the cover test for an adequate period of time Speak out loud “On covering the right eye, there is a small / moderate / large left esotropia ”.  Tropia may be unilateral or alternate between eyes (fixation switches after each cover). During cover testing, look closely for latent nystagmus and / or dissociated vertical deviation (DVD). The uncover test is only useful if the cover test has demonstrated orthotropia in the other eye Alternate Cover for Tropia & Phoria Perform alternate cover tests with  fast  “switch” (then  pause ) to break fusion

10. Cover-test Distance (CTD) in Primary If vertical deviation / height (“R over L” or “L over R”; hyper / hypotropia if 1 eye fixing) A nd possible CNIV palsy → Perform Parks 3 step test If horizontal deviation in primary and possible CNVI palsy → Check for incomitance in left / right gaze ± Chin up / down for alphabet patterns (“V” pattern think of: Browns, IOOA, bilateral CN IV palsy). Ask yourself where the eso or exo is worst: Eso deviation worst (points to apex of letter) in chin-up ( downgaze ) = V pattern Exo deviation worst (points away apex of letter) in chin-up ( downgaze ) = A pattern Cover-test Near (CTN) in Primary You  must  use a good accommodative target (not a finger, light) ± Reading add

11. Notes on Cover-Testing Cover the fixing eye first F reely alternating tropia suggests similar visual acuity in both eyes When checking for incomitance , only do alternate cover test (not cover, uncover). Keep the patient dissociated by keeping one eye covered at all times Prism cover test: Cover the deviating eye with a prism & cover, Move the paddle to cover the fixing eye, increase the prism until there is no longer refixation When measuring CTN with prism, G et the child to hold the target on your nose or Put a small sticker on your nose! When measuring DVD, place prism apex up in front of the affected eye Prism cover test

12. 5. Ocular Rotations Either a fixation target or a pen torch may be used. A pen torch has the advantage that corneal reflexes can be viewed B ut some examiners don’t like this technique. Unlike cover testing for near, accommodation doesn’t have to be controlled. Gently hold your hand out near the patient’s chin or forehead (this “reminds” the patient to keep their head still) A nd make your movements  slow  but deliberate A void multiple passes The upper eyelids may need to be elevated when the patient is in downgaze . 1. Horizontal pass (twice)- watch lids / pupils for aberrant regeneration / Duane 2.“H ” pattern 3.± Straight up / down (thyroid eye disease TED, A/V patterns) 4.± Convergence Ocular Rotations “ H” pattern

13. Notes on Ocular Rotations You  must  know which eye is fixing Grading : - 8 :eye looking in opposite direction to attempted extreme gaze - 4 : eye looking in primary on attempted extreme gaze : normal Say “- 2 defect of elevation in abduction…”,  not  “restriction” (unless you have demonstrated this first) Check  ductions  (cover the contralateral eye ) I f there is a defect (goes further if palsy is present, unlike restriction) Record versions and ductions (in square brackets) e.g. - 4[0] For all muscles other than the medial / lateral rectus , L ook for a vertical movement on cover testing at extremes of gaze An up / down movement on attempted horizontal movement is an “up / downshoot ” For SR / IR, SO / IO over / underaction look for vertical movement W hen alternate cover testing at the ends of the “H” You can only say “there is suggestion of e.g. IOOA ”   Prior to performing an alternate cover test SR / IR, SO / IO

14. Grading and Documenting Ocular Rotations A : Grade 0 is normal. For horizontal versions a grade of -4 indicates that the eye remains in primary when attempting to fully abduct or adduct. B: When testing ocular movements at the extreme corners of gaze (at the ends of the “H”), +4 indicates overaction to vertical, -4 indicates underaction to horizontal). C: two eyes are drawn and points of gaze are graded. Versions versus Ductions If ductions (monocular) have a different grade to versions (binocular ), T hey are written in square brackets

15. 6.Saccades (Horizontal ± Vertical) Test monocularly Easier to inspect one eye at a time Use finger & pen ~20cm apart in field of expected deficiency. Don’t “wiggle” the targets i . Normal (Fast) Occurs in restrictive disease up to the point of restriction ii. Abnormal Occurs in neurological and myogenic disease Hypometric “Undershoot” Generalised slow saccades occur in supranuclear palsy Parinaud - worse up Progressive supranuclear palsy PSP- worse down, CPEO and myaesthenia gravis (“intra-saccadic fatigue”) Uni -directional slow saccades occur with CN palsies and INO Hypermetric Cerebellar Disease

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