5. Evaluation of a case of strabismus – Part 1

[Audio] Orbit Eye Center for Pediatrics & Oculoplasty.

[Audio] EVALUATION OF A CASE OF STRABISMUS. EVALUATION OF A CASE OF STRABISMUS.

[Audio] Main components of evaluation of a case of strabismus are: History, vision evaluation and prelimary examination History Vision evaluation Prelimary examination Head posture evaluation II. Motor evaluation • Evaluation for ocular deviation Cover tests Corneal reflex tests Subjective tests for measurement of deviation Measurement for cyclo deviation • Assessment for ocular movements Evaluation of duction Evaluation of version Evaluation of vergence III. Sensory evaluation Worth Four dot/light test Bagolini glasses 4 Prim diopter test Titmus Fly test After image test.

[Audio] 1.HISTORY A detailed meticulous history taking before beginning the examination is very important in and the management of a case of squint. A complete history taken should contain the following information. 1. Age of the patient 2. History of present illness. Information about deviation of eye should include: • Time when first noticed. It is desirable to document the age of onset of deviation or symptoms. • Onset, sudden or gradual. • Constant or intermittent deviation. • Unilateral or alternating deviation. • If alternating, which eye more frequently fixates (dominating eye). • Alleged cause, if any, such as trauma, illness, psychologic disturbance, change in occupation, increase in close work, etc. Abnormal head posture • Associated symptoms such as diplopia, blurred vision, headache, asthenopia..

[Audio] 3.Birth History Gestational Age and Birth Weight: Determine if the child was born prematurely or had a low birth weight, as these factors can be associated with visual problems. Trauma During Labor: Identify any trauma sustained during birth that could have impacted the child’s vision. Mother’s Health During Pregnancy: Inquire about the mother’s health, including any infections, illnesses, or medications taken during pregnancy. 4.Family History Refractive Errors: Check for a family history of myopia, astigmatism, and other refractive errors. Strabismus: Identify any family history of strabismus, as there may be a genetic predisposition 5. Past History • General ill health • Any systemic disease • Any ocular defect.

[Audio] 6.History of previous treatment a. Optical treatment • When and how long? • Effect of glasses on the deviation. • Date of last refraction. b. Orthoptic treatment. • Occlusion. Type, when, how long, effect on vision. • Exercises. When, type, how long, effect on deviation. c. Surgical treatment • When performed? • Eye operated: Right, left or both. • Muscle touched. Medial, lateral or both (if known). • Patient's/parents' opinion about the result of surgery.

[Audio] 2.VISION EVALUATION Testing of visual acuity of each eye separately is critical in evaluation of any patient with strabismus. Visual acuity should be tested without glasses and with glasses (if worn); and for near and distance vision. Aims of examination are: –– To find the functional status of either eye. –– To record patient’s vision according to his age. –– Before proceeding on to ophthalmic examination, it is important to get an idea of visual potential of either eye..

[Audio] Infants(Birth-14 months) Pre-Verbal Children Toddlers (14 months - 21/2years) Preschoolers (2 1/2 years - 5years) School going children (5years- 15 years) & age above 15 1.Fixation preference test. •Does he have a central/steady & maintained fixation.? •Does he follow target? •Does he get upset when u close one eye? 2.OptokineticNystagmus (OKN) 3. Preferential looking test (PL) 4.Visual Evoked Potential (VEP) 1. The Cardiff acuity Test 2.Dott Visual Acuity Testing. 1.LEA Symbols 2.Allen Picture Card 3.Broken Wheel Test 4.Tumbling E chart 5.Landolt C chart 6.Sjogren hand test 7.HOTV test 1.Tumbling E chart 2. Landolt C chart 3.Sjogren hand chart 4.Snellen's chart 5.LogMAR chart..

[Audio] 3.PRELIMARY EXAMINATION 1. General Appearance: The examination starts as the patient enters the room. Easily identified conditions include microcephaly albinism Down syndrome cerebral palsy cranial dysostosis hydrocephalus - Conditions associated with a high incidence of strabismus and eye movement problems.

[Audio] 2.Abnormal Head posture? When observing a patient's appearance, it is important to look for any abnormal head positions An abnormal head posture has three possible components: Face turn to right /left → horizontal deviation Head tilt to right or left shoulder → torsional deviation Chin elevation or depression → vertical deviation To compensate for deviation To permit BSV To eliminate diplopia and place eyes in most comfortable position Patient position head to reduce need for affected muscle to contract.

[Audio] 3.The Eye Lid Evaluation The eyelid position is symmetrical on both sides, with the height of each palpebral fissure measuring between 9-11 mm. Palpebral Fissures Variations from the normal shape or size of the palpebral fissure can lead to pseudo-strabismus or indicate certain ocular motility disorders. An increase or decrease in the height of the palpebral fissure can be characteristic of some incomitant conditions. For example: Narrowing of the fissure on adduction and widening on abduction are diagnostic features of Duane's retraction syndrome. The fissure commonly widens on adduction in Brown's syndrome.

[Audio] Epicanthus Epicanthus is a fold of skin which arises in the medial portion of the upper eyelid and is inserted into the lower eyelid at the medial canthus. It is usually bilateral and symmetrical Epicanthus gives rise to pseudoesotropia in young children Epicanthus is physiological and usually disappears by 7 or 8 years of age Blepharophimos Blepharophimos is an upward fold of the skin of the lower eyelid near the inner corner of the eye, where the patient has bilateral ptosis with reduced lid size, vertically and horizontally. Unilateral Ptosis or Eyelid Retraction These conditions can cause pseudo-hypertropia or pseudo-hypotropia, respectively.

[Audio] Pupil Examination It helps detect underlying neurological disorders, such as Horner's syndrome or third nerve palsy, which can present with both strabismus and characteristic pupil abnormalities. Interpupillary distance (IPD) should also be inspected and measured. Unusually, narrow IPD may be the cause pseudoesotropia and an exceptionally wide IPD may be a cause of pseudoesotropia. Media and Fundus Examination It may reveal associated diseases of the ocular media, retina or optic nerve..

[Audio] Refraction Refraction is critically important in strabismus patients for several reasons: Diagnosis and Management: Accurate refraction helps in diagnosing the type and extent of refractive errors, such as myopia, hyperopia, and astigmatism. These errors can contribute to or exacerbate strabismus. Correcting the refractive error can sometimes align the eyes without the need for surgery. Treatment of Amblyopia: Many strabismus patients have amblyopia (lazy eye), which is often associated with significant refractive errors. Correcting the refractive error is the first step in treating amblyopia, as it ensures that the amblyopic eye receives a clear image, which is essential for visual development..

[Audio] Improvement of Binocular Vision: Proper refraction can improve binocular vision and depth perception. Strabismus can interfere with the brain's ability to fuse images from both eyes, leading to issues with depth perception and binocular vision. Correcting refractive errors helps to provide clear images to both eyes, which is essential for the development and maintenance of binocular vision. Reduction of Strabismic Angle: In some cases, correcting a refractive error can reduce the angle of strabismus. For example, hyperopic (farsighted) patients may have esotropia (inward turning of the eye) that decreases when the hyperopia is corrected with glasses..

[Audio] Surgical Planning: For patients who require surgical intervention, knowing the exact refractive error is important for surgical planning and predicting postoperative outcomes. Accurate refraction ensures that the surgical correction addresses all aspects of the patient's visual needs. Overall Visual Comfort: Providing the correct refractive correction improves overall visual comfort and reduces symptoms such as eye strain, headaches, and visual fatigue, which are common in strabismus patients with uncorrected refractive errors..

[Audio] EVALUATION OF MOTOR STATUS Ocular deviation - Estimation of angle of squint. Position of corneal reflex Cover test. Measurement of angle of squint. Objective methods Subjective method Motor cooperation of eye - Extra ocular movements Duction Versions Vergence.

[Audio] Light Reflex Tests 1.These tests provide an estimate of the size of the strabismus 2.Look for the position of the corneal light reflex of a spotlight placed 33 cm away from the patient cornea. 3.Reflections are examined with both eyes open. 4.A positive or negative angle kappa can cause pseudo-exotropia or pseudo-esotropia, respectively. An angle kappa occurs when the pupillary axis and the visual axis of the eye do not coincide. Pupillary Axis: The line passing through the center of the apparent pupil, perpendicular to the cornea. Visual Axis: The line of sight connecting the fovea with the fixation point. Angle Kappa: Formed at the intersection of the pupillary and visual axes at the pupillary plane Pupillary Axis Position: Touches the posterior pole of the globe slightly nasal and inferior to the fovea..

[Audio] Positive Angle Kappa exotropia: When the eye fixates on a penlight, the corneal reflection will be slightly nasal to the center. Negative Angle Kappa esotropia: If the fovea is nasal to the point where the optical axis intersects the globe's posterior pole, the corneal reflection will appear on the temporal side of the pupillary center..

[Audio] Methods Using Corneal Reflections: Hirschberg Test The Hirschberg Test also known as the corneal light reflex test is quick and simple way to Check is squint present or not Direction of the squint Rough estimate of the amount of squintشغل سر.

[Audio] Procedure The patient should be seated comfortably at a distance of about 50-100 cm from the examiner. Ensure that the patient is looking straight ahead at a fixation light, which is typically a penlight or similar light source. Use a penlight or a small, bright light directed towards the patient’s eyes. Observe the position of the light reflexes on the corneas of both eyes. Normally, the light reflexes should be symmetrically positioned on the corneal center of both eyes The degree of strabismus can be roughly estimated by measuring the decentration of the reflex from the center of the pupil in millimeters. One millimeter of the deviation of the reflex is equal to 15 prisms..

[Audio] Analysis: Hirschberg corneal reflex test depicting Ortho position Right esotropia Right exotropia 15° 15° 30° 30° 45° 45°.

[Audio] Krimsky Test To estimate the angle of strabismus (squint) when the deviated eye cannot fixate due to poor vision or other factors. Procedure Position the patient comfortably at a distance of approximately 50-100 cm from the examiner. Use a bright spotlight or penlight to shine on the cornea of the patient's eyes. The light should be positioned in a way that it causes a corneal light reflex. Place a prism bar in front of the good eye (the eye with better vision or the non-deviated eye). Start with a low power prism and gradually increase the prism strength while observing the position of the corneal light reflex in the deviated eye. The goal is to adjust the prism until the light reflex in the deviated eye appears to be centered on the cornea, similar to the reflex in the good eye. The power of the prism at which the corneal reflex in the deviated eye aligns with the center of the cornea indicates the angle of deviation. Note the prism power used; each prism diopter corresponds to approximately 1 degree of deviation. The Krimsky's corneal reflex test. A, right exotropia; B and C, prism base-in of increasing powers are placed in front of the fixing left eye till the corneal reflex centres in the right eye (C); D, optical principle of the prism reflex test..

[Audio] Synaptophore (Major Amblyoscope): A foveal slide is placed is front of the fixing eye and the position of the corneal reflexes in the eyes are noted when the synaptophore arms are at 0. The arm in front of the fixing eye is moved until the reflex in the squinting is centered. The angle is measured in prism diopters and in degrees from the scale..

[Audio] Cover Test This is mainly an objective test, which is the corner stone of the investigation of strabismus Perform the cover tests both with and with Out glasses. Conduct the tests at near (33 cm), distance (6 m)..

[Audio] Methods of cover tests To confirm the presence of a manifest squint 1.Direct cover test To establish the presence and type of heterophoria (latent deviation). 2.Cover-uncover test To establish whether the squint is unilateral or alternate and also to differentiate concomitant squint from paralytic squint 3.Alternate cover test.

[Audio] 1.Direct Cover Test Purpose: To confirm the presence of a manifest squint Procedure: Use an opaque or translucent occluder to cover one eye. Observe the movement of the uncovered eye. In the presence of manifest squint, the uncovered eye will move in the opposite direction to take fixation No movement of the uncovered eye on covering the seemingly fixating eye indicates any of the following: • No squint (pseudo strabismus) • Gross eccentric fixation (there may be very small or no movement of redress in the uncovered deviated eye) • No vision in the deviated uncovered eye. Direct cover test depicting left exotropia.

[Audio] 2.Cover-Uncover Test Purpose: To detect a tropia and distinguish it from a phoria. Procedure: Use an opaque or translucent occluder to cover one eye. Observe the movement of the uncovered eye. Tropia: If a tropia is present, the non-occluded eye will move to fixate on the target when the occluder is removed. Phoria: If no tropia is present, the non-occluded eye will remain stationary. If there’s a phoria, the eye behind the occluder will deviate and then return to its original position when the occluder is removed. This test is typically done first to identify any manifest deviations. Cover-uncover test depicting exophoria. Note orthophoria in primary position (A) and immediate inward movement of right eye on removal of the cover (B and C)..

[Audio] 3.Alternate Cover Test Purpose: To measure the total deviation (tropia plus phoria). Procedure: The examiner alternately covers one eye and then the other, ensuring to hold the occluder over each eye for a few seconds. Observe the movement of the eyes as the occluder is switched. Observation: The speed and accuracy of eye movement when the occluder is switched can indicate the control and magnitude of the deviation. Performed after the cover-uncover test to assess the total deviation and check the efficiency of eye alignment. Alternate cover test depicting alternate exotropia Alternate cover test depicting alternate exotropia.

[Audio] Measurement of Deviation The angle horizontal and vertical squints can be measured objectively and subjectively. Objective methods 1.Prism bar cover test 2.Synaptophore Subjective method Maddox rod.

[Audio] PRISM BAR COVER TEST - PBCT The PBCT is a simple and popular method for objectively measuring the angle of deviation in various diagnostic positions of gaze. Required instruments: Horizontal and vertical prism bars or loose prisms. An occluder Near accommodative target. For example, near fixation stick Distance target. For example, most commonly a Snellen chart is utilized.

[Audio] Procedure for Prism Cover Test (PCT) Conduct the test at near (33 cm), distance (6 m), and, if necessary, at greater than 6 meters. Ensure the patient is sitting upright with their chin and head straight. Determining Prism Orientation Cover Test Results: Based on the cover test results, determine prism orientation: BASE IN for exodeviation (eye turned out) BASE OUT for esodeviation (eye turned in) BASE UP for hypodeviation (eye turned down) BASE DOWN for hyperdeviation (eye turned up) Measure in the primary position first, then in any other positions of gaze of concern. Near Fixation: For near fixation, have the patient hold an accommodative target (fixation stick) at 33 cm, in line with their visual axis. Ensure the patient maintains accommodation by reading aloud the letters at the top of the fixation stick. Hold the prism bar or loose prism over the patient's deviating eye, starting with a small strength prism. If the deviation appears large, start with a larger strength prism. Perform an alternate cover test with the prism present..

[Audio] Ensure the test is performed correctly to achieve maximum dissociation and determine the total deviation size (latent and manifest). While performing the alternate cover test, observe the patient's eye for movement. If movement is seen, increase the prism strength. If the deviation exceeds 50 prism diopters and a single prism bar cannot be used, stack or split the prisms. Increase the prism strength until the eye under the prism shows no movement, indicating the deviation is neutralized. To confirm neutralization, use the next prism of increasing strength to produce movement in the opposite direction, indicating overcorrection. After recording the near PCT results, repeat the procedure at 6 m with a Snellen chart. If needed, perform the test at greater than 6 m with the patient fixating out the window. Continue the test until neutralization has been established at all required distances.

[Audio] Uses of PBCT: 1. Nature of Deviation: Determine if esotropia is basic, convergence excess, or divergence insufficiency type. Determine if exotropia is basic, convergence insufficiency, or divergence excess type. 2. Accommodative Element: Measure deviation for far and near with and without glasses (including bifocals). 3.Incomitance: Detect incomitance by performing the test in 9 cardinal positions of gaze. 4. A-V Patterns: Measure deviation in upgaze of 25° and downgaze of 35°. 5. Primary vs. Secondary Deviation: Measure deviation with right and left eye fixating alternately. 6. Divergence Excess: Differentiate between divergence excess and simulated divergence excess exotropia by measuring deviation before and after prolonged occlusion..

[Audio] Maddox rod A glass rod (or a series of parallel glass rods) that converts the image of a light source into a streak of light perpendicular to the axis of the rod. The position of this streak in relation to the image of the light source seen by the fellow eye indicates the presence and amount of heterophoria Red, White or Green parallel plano convex cylinder lens, which refracts light rays so that a point source of light is seen as a line or streak of light. Due to the optical properties. The test is based on the principle of diplopic projection..

[Audio] Equipment required for testing Maddox rod Light source (Pen Torch) at near 33 cm, (Fixed target light) at distance 6m Base in, base out, base up, base down prisms bar Trial frames.

[Audio] Method of Assessment Method for measuring horizontal deviations: When performing the test, the room lights should be dimmed and only one light source should be visible. When testing at near, the patient is to fixate on light source at 33 cm, which is held at eye level. When testing at distance, the patient is to fixate on a light source at 6m. Patient is instructed to fixate on the light source with both eyes opened. The Maddox rod is then placed over the fixating eye.

[Audio] To measure the horizontal deviation The Maddox rod is placed in front of the right eye making the red line will be vertical. The patient is then asked whether the white light is superimposed on the red line, or if it is to the left or right of the red line. If the patient saw a red line to the left and white light to the right, they are said to have exotropia or Exophoria (crossed diplopia) in which base in (BI) prisms. If the patient saw a red line to the right and white light to the left, they are said to have esotropia or Esophoria (uncrossed diplopia) in which base out (BO) prisms..

[Audio] Method for measuring vertical deviations: The patient is holding the Maddox Rod in front of their right with the cylinders vertical, making the red line horizontal. The patient is then asked whether the white light is superimposed on the red line or if it appears above or below the red line. If the line appears below the light, there will be a hyper-deviation in which base down prisms are used to measure and correct the deviation. If the line appears above the light, there will be a hypo-deviation and base up prisms are used measure and correct the deviation. If the white light is superimposed on the red line, there are ne vertical deviations present.

[Audio] Advantages and Disadvantages •Advantages Subjective test Can easily be performed Simple and fast technique Can be used on children •Disadvantage Cannot be done when there are sensory anomalies present. Cannot be performed if a patient has suppression, as they are unable to see the light. Cannot be performed if there is Abnormal Retinal Correspondence (ARC), as the angle of separation of the images will not correspond to the angle of deviation. Cannot differentiate between tropias and phorias..

[Audio] Double Maddox rod test It is a subjective test which uses two Maddox rods, one before each eye. It can also be used to assess torsion and measure cyclotropias. This test can be done in all the position of gazes for comparison..

[Audio] Procedures 1. The room lights should be dimmed and only one light source should be visible. 2. Maddox rods are placed into the trial frames, one before each eye 3. Cylinders are placed into trial frame vertically (90), making the two red lines horizontal. 4. Patient is instructed to fixate on the light source with both eyes opened 5. When testing at near, the patient is asked to fixate on light source at 33 cm, which is held at eye level. When testing at distance, the patient is to fixate on a light source at 6m. 6. If patient feels difficult to compare the orientation of streaks, place the loose prism in the trail frame. Vertical prism ( base-up, or base-down) can also be added into the trial frames to separate the two red lines (This avoids confusion if the patients claim that they only see one red line). if the patient does not have any vertical or horizontal separation of streaks, the streaks can be difficult to compare. Thus, loose prisms can be used to separate the images/streaks to let easy comparison or, if the patient has large horizontal or vertical deviation, prisms can be used to bring the streaks closer together to let the easy comparison..

[Audio] 7. Patient is asked to rotate OR the examiner rotates the cylinders with the axis knob on the trial frame until the 2 red lines are parallel 8. The amount of cyclodeviation is measured in degrees, utilized from the scale on the trial frame 9. if the two streaks are parallel to each other without any rotation of Maddox Rod, patient does not have cyclodeviation. 10. Examiner can either use base-out, base-in, base-up or base-down prism depending on the deviation. For example: a patient with a large esotropia may need a base-out prism placed in front of deviated eye to bring the streak corresponding to this eye closer to another streak. 11. This test can be repeated for the secondary and tertiary positions of gaze..

[Audio] Interpretation Starting from 90◦; look at the superior part of the Maddox rod, if rotation of grooves of the maddox rod towards the nose (nasally) measures the incyclodeviation and if towards the lateral side (temporally) measures the excyclodeviation. The amount of cyclodeviation is measured in degrees, shown by the scale in the trial frame. For example: In Right Eye, if the axis or grooves of maddox rod is rotated at 80◦, the patient has 10◦ incyclodeviation but if the axis of maddox rod is rotated at 100◦, the patient has 10◦ excyclodeviation. In most of the cases double maddox rod test helps in detection of the defect of the oblique muscles. For patients with unilateral superior oblique weakness the excyclophoria is generally between 1 to 7 degrees, whereas in bilateral superior oblique weakness the excyclophoria is typically greater than 10 degrees..

[Audio] Advantages • Simple and fast technique • Can be used on children, if they can respond reliably Disadvantages • Cannot be done when there are sensory anomalies present • Cannot be performed if a patient has suppression, as they are unable to see the light • Cannot be performed if there is Abnormal Retinal Correspondence (ARC), as the angle of separation of the images will not correspond to the angle of deviation; defeating the purpose of the test. • Cannot differentiate between tropias and phorias • Subjective test.

[Audio] OCULAR MOVEMENT The ocular movements may be described as monocular (ductions) or binocular (versions and vergences). Ductions include the following movements: 1. Adduction: An inward movement of the eye towards the nose, a medial rotation along the vertical axis. 2. Abduction: An outward movement, a lateral rotation along the vertical axis. 3. Supraduction (Sursumduction): An upward movement or elevation along the horizontal axis. 4. Infraduction: When the eye moves down (depression) along the horizontal axis. 5. Incycloduction (intorsion): When the eye makes a rotatory movement along the anteroposterior axis such that the superior pole (12 O’clock point) rotates towards the nose. 6. Excycloduction (extorsion): When the eye rotates in a manner that the 12 O’clock point rotates away from the nose..

[Audio] Ductions Temporal Medial. 47. Aducciön Abcucciön SupraducciOn Infraducciön Intorsiön (incicloducc On) Extorson (excicloducciön).

[Audio] Binocular movements: The term binocular movements may be divided into 2 groups: Versions & Vergence A. Versions (Conjugate movements) These are synchronous and symmetric movements of both eyes in the same direction. These are classified according to the direction of binocular movements as follows . 1. Dextroversion: When both eyes are turned to the right. It is affected by a simultaneous contraction of right lateral and left medial rectus muscle. 2. Levoversion: When both eyes are turned towards left by contraction of left lateral and right medial rectus. 3. Supraversion: When both eyes are rotated straight up. It is affected by a simultaneous contraction superior rectus and inferior oblique of both eyes. 4. Infraversion: When both eyes are turned straight down, and is caused by a bilateral contraction of inferior rectus and superior oblique muscles. 5. Dextrodepression: When both eyes are turned down and to the right. It is caused by a simultaneous contraction of right inferior rectus and left superior oblique..

[Audio] 6. Dextroelevation: When both eyes are turned up and to the right. It is caused by a simultaneous contraction of right superior rectus and left inferior oblique. 7. Levoelevation: When both eyes are turned up and to the left, a position achieved by a simultaneous contraction of left superior rectus and right inferior oblique. 8. Levodepression: When both eyes are turned down and to the left. This position is brought about by a simultaneous contraction of left inferior rectus and right superior oblique. 9. Dextrocyclovesion: When the eyes rotate along the anteroposterior axis so that the superior pole (12 O’clock point) rotates to the right side. This movement is brought about a simultaneous contraction of inferior rectus and inferior oblique muscle of the right eye, and superior rectus and the superior oblique of left eye. 10. Levocycloversion: A movement just opposite of dextrocycloversion..

[Audio] . 50. Right superior rectus Left inferior oblique Right lateral rectus Left medial rectus Right inferior rectus Left superior oblique Right superior rectus Left superior rectus Right inferi rectus Left inferior rectus Right inferior oblique Left superior rectus Right medial rectus Left lateral rectus Right superior oblique Left inferior rectus.

[Audio] Vergences Vergences are disjugate, synchronous and symmetric movements of both eyes in the opposite direction. Depending upon the direction of movement vergences may be described as follows: 1. Convergence: Medial movement that occurs due to contraction of both MR muscles 2. Divergence: Lateral movement that produced by contraction of both LR muscles 3. Vertical vergence: Contraction of elevators of one eye and depressors of other 4. Cyclovergence: Simultaneous rotation of the eyeballs so that the superior rims of both corneas move laterally or medially.