Strabismus Patients Evaluation

Strabismus Patients EvaluationMohammad Sazzad HossenB. Optom (VMU), M. Optom(CO), IndiaICLEP (LVPEI, Hyderabad)Trained from TSNA (Chennai), IIEIH (Dhaka), CEITC (Ctg.)Consultant Optometrist - Ad-din Medical College Hospital

DefinitionStrabismusCase StudiesAnatomyAssessmentManagement

Strabismus is a visual problem in which the eyes are not aligned properly and point in different directions. One eye may look straight ahead, while the other eye turns inward, outward, upward, or downward.

SQUINT

Concomittant (non paralytic)MonocularEso Tropia or ConvergentExo Tropia or DivergentHyper TropiaHypo Tropia Incyclo & Excyclo

AlternatingConvergentDivergent

Inward turning is called esotropia Outward turning is called exotropia Upward turning is called hypertropia Downward turning is called hypotropia.

b-PARALYTIC STRABISMUS

1- 3RD( oculomotor)cranial nerve palsy(all extraocular muscles involved except the lateral rectus & the superior oblique muscle)2- 6th cranial nerve (abducent)=paralysis of lateral rectus muscle .3- 4th cranial nerve (trochlear)=paralysis of superior oblique muscle

Causes of acquired ocular motility disorderNeurogenic (ocular motor nerve lesion):Vascular (diabetes or hypertention).Demyelinating (multiple sclerosis).InflammatoryCompressive (aneurysm or tumour)Trauma or surgery.MyogenicMyasthenia gravisOcular myopathyRestriction Dysthyroid ophthalmopathyTraumaInflammationOrbitalOrbital mass restricting eye movement

Convergence Insufficiency.

Students usually suffer from this problem.

A third type of exotropia is an apparent weakness of convergence, called convergence insufficiency. The entity frequently affects young adults and is a major cause of asthenopia, or tired eyes, while doing near work in this age group.

Risk factors for developing strabismus include:

Family history individuals with parents or siblings who have strabismus are more likely to develop it. Refractive error people who have a significant amount of uncorrected farsightedness (hyperopia) may develop strabismus because of the additional amount of eye focusing required to keep objects clear. Medical conditions people with conditions such as Down syndrome and cerebral palsy or who have suffered a stroke or head injury are at a higher risk for developing strabismus.

SQUINT Assessment

HISTORYAge of PatientComplaint:-Age of Squint onset (early onset/ long duration / constant angle / previous photos) Is it Sudden Or Gradual ?Direction of deviation patient / parent notedIs it Constant? Or Sometimes (INTERMITTENT)Noticed in One Eye or Both? (U/L OR ALTERNATE)Diplopia? Asthenopia? Abn.Head PostureBirth HistoryRegarding Pregnancy & DeliveryDevelopmental Milestones(Delay)Family History Squint/ Refractive Error / Lazy eyePersonal History DM /HTN / ThyroidTreatment HistoryGlasses /Occlusion Therapy /Orthoptic Exercise / Prev. Surgery

..Looks can b really Deceptive Lid Fissure:- PtosisMongoloid/Anti mongoloidExophthalmos / enophthalmosNasal BridgeClosure of one eye in bright lightEpicanthal folds

Head Posture (AHP)Face Turn (Right/Left)Head Tilt (Right/Left Shoulder)Chin (Elevation/Depression)

Facial AsymmetryFixation PreferenceNystagmus

INSPECTION

MOTOR EXAMINATION

Extra-Ocular Movements

Points to Remember for EOM

To check if all eye muscles r working together.Patient and examiner positioned at same levelRoom should be properly illuminated.Sit in front of the patient so that BE eyes can be seen simultaneously.Remove any Spectacles.( to remove prismatic effect)USE A PENLIGHT.40 CM DISTANCE,SHINE ON FOREHEAD Move in 6 diagnostic/H position.

ADDUCTION:- is normal when NASAL 1/3RD CORNEA crosses nasal punctum

ABDUCTION:- is normal when TEMPORAL LIMBUS touches lateral canthus.

INFERIOR OBLIQUES:- on lateral version , upwards deviation from the horizontal line passing through centre of pupil

SUPERIOR OBLIQUES :- on lateral version, downwards deviation from the horizontal line. ELEVATION :-DEPRESSION :-

Measurement of DeviationObjective TestSubjective TestHirshberg TestPrism Alt.Cover Test(PACT)Krimsky Test

Maddox RodHess Screen TestSynaptophore Test

Dissociation of EyesCover testDiplopia or displacement tests (vertical )Distortion tests (Maddox Rod)Independent objects (Maddox Wing)

PRE-REQUISTE FOR CT/CUT/ALTSimplest methodObjective assessmentVision More than 6/60 in BE to see the targetCentral fixation in BEIf Bifocals are worn, near deviation measured through reading segmentCover test only way to distinguish between phoria and tropiaPerform on all patients with and without Rx

Cover Test / Cover-Uncover/ Alternate Cover TestHelps to establish Ortho-tropic or not.Is Squint Latent= PhoriaIs Squint Manifested = TropiaDirection of DeviationFixation BehaviorCheck for Distance & Near

Patient fixates on smallest letter seen by poorest eye. Use an opaque occluderDont go too quicklyCover placed before 1 eye and then removedObserve the uncovered eye for movement; if movement is present then patient has a squintIf a squint is present there cannot be a phoria

Cover Test

Covering one eye of patient with normal binocular vision interrupts fusion.

See for the movement OF OTHER EYE

When eye is uncovered ,it will reestablish binocular fixation

Imp. of Test:- Detects & Confirms Tropias

Cover- Uncover TestExaminer OBSERVE THE COVERED EYE AS COVER IS REMOVED.

In Hetrophoria,covered eye will deviate toward hetrophoric position.

When eye uncovered Reestablish Binocular Vision.

Imp.of Test:- used to find out PHORIAS

Alternate Cover TestIdentify (Tropia + Phoria)

Hold occluder over one eye for several secondsDissociates binocular vision

Rapidly move occluder to other eye

Observe Refixation shift of unoccluded eye

Prism Cover Test by Prism Bar

Base Out for EP and ETBase In for XP and XT

Distortion TestMaddox RodCan be used for vertical and horizontal deviations

Maddox RodPlace rod before right eyeUse spot light and dim room lightsAsk is red line to the left or right of the spotlight?If rod is to the right SOPIf rod to the left XOPUse prism to align rod and spotlight

Maddox Rod

Hirschberg Corneal Reflex (HBCT)1mm shift = 7 or 15 *Uses 1st Purkinje Image

Krimsky Test /Modified HBCTAngle of strabismus is evaluated, when the light is projected straight ahead, and subsequent prisms (prism bar) are placed

Based on HERINGs LAW of equal innervation

BEFORE THE FIXING EYE until symmetrical light reflexes are seen on the cornea of both eyes.

SENSORY EXAMINATIONSTEREOPSISSUPPRESSION & DIPLOPIARETINAL CORRESPONDANCETO BE DONE WITH FULL OPTICAL CORRECTIONTO BE DONE PRIOR TO ANY DISSOCIATION

TITMUS FLY TEST Gross StereoacuityTop of Upper Wings:2000secondsBottom of Lower Wings:1150 secTip of Abdomen:700 sec

Fine Stereoacuity Circles 1-3:800-200sec4-6:140-80 sec7-9:60-40 sec

AnimalsA row:400secB row:200secC row:100sec

TNO TESTTHE NETHERLANDS ORGANIZATIONGraded from 15-480 arc sec8 plates; 480/240/120/60/30/15

1ST 3 plates to check for presence of stereopsis4 is SUPPRESSION TEST PLATEIf a child see 2 circle ask for larger circle5,6,7for degree of steropsisSpecial Glasses RequiredKept at distance of approx 30 cms

Cost around 20,000!!!!!!!!!Checks NEAR STEROPSIS ONLY

FRISBY DAVIS DISTANCE TEST

Diplopia TestPatient is asked to comment onPosition, Brightness, Separation between imagesSTIMULATOR

NON SURGICALOPTICAL (eyeglasses, contact lenses, prism lenses) Medical Vision therapy or Orthoptic Exercise

SURGICAL eye muscle surgeryStrabismus Management

What is the prescription aim?Our purpose is best visual acuity in distance versus binocular alignment

Certainly ,we want to eliminate any amblyogenic factors by using the optical correction and consider the binocular status

Prescribing for ChildrenIn adults, the correction of refractive errors has one measurable endpoint: the best corrected visual acuity. Prescribing visual correction for children often has two goals:1- providing a focused retinal image2- achieving the optimal balance between accommodation and convergence.Unequal clarity in vision represents an obstacle to fusion and can facilitate suppression.Significant RE, especially astigmatism and anisometropia, need to be corrected.

All patients in minus lenses should be seen within 3 to 4 weeks after starting the therapy. Minus lenses should be discontinued if esotropia develops. There are studies that suggest that this treatment may induce myopia

Minus Lens Therapy

Occlusion Part time patching of the non-deviating eye for four to six hours daily may convert an intermittent exotropia to a phoria.Initially the results are evaluated after 4 months of occlusion.If the angle of deviation is decreased the occlusion should be continued and assessment made every 4 months until no further change occurs. In case there is no improvement for 4 months, it is discontinued

Various Non-Surgical Therapies for Intermittent Exotropia

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Indications for Surgery

OrthopticsGoal is give comfortable binocular visionused to combat suppression, amblyopia, ARC, enhance fusional amplitude and improve stereopsisIn successful case transform tropia to phoria but not eliminate it

Precise measurement of; angle alpha, the objective and subjective angle of deviation, abnormal retinal correspondence, vertical and torsional deviations and the area and density of suppression

Convergence insufficiencyMost effective treatmentConverge on an approaching object such as pencil or a light while red filter is placed over one eyeAware of physiologic diplopia of a distant object while fixing on a target at nearTraining fusional convergence with base out prism or major amblyoscopeBase out prism used during reading and continue on home with increasing power

Fusion trainingTraining of fusion amplitude enable symptomatic heterophoria patient more comfortableDone by amblyoscope / synoptophore or prism exerciseOrthoptic is aimed to awareness of physiologic diplopia in heterophoria and diplopia in heterotropia. Once diplopia elicited vergence control activated. Forcing suppressed area concurrently with corresponding area of dominant eye. Stimulation of retina of deviated eye by moving visual target on major amblyoscope back and forth across suppression scotoma. Suppression cannot be effectively eliminated by orthopticAntisuppression Training

Exercise 01: Pencil PushupsStep 1Hold a pencil on front of you at arm's length. The pencil should be vertical, with the tip of the sharpened pencil at the top. The pencil should be directly in front of your face, with the tip just below eye level.Step 2Move the pencil slowly toward your face as you concentrate and focus on the point. Soon you'll notice that you see two pencils rather than one. Stop.Step 3Look away from the pencil briefly to rest your eyes. Focus on something across the room for two or three seconds, and then look back at the pencil point where you've stopped it close to your face. Look at the pencil point carefully, and to try to focus so that the double vision disappears and you only see one pencil.

EXERCISE 2 DOT CARDHold the dot card near your nose with the line vertical and facing away. Angle the far end slightly up. Squeeze the card very gently to keep it rigid.Look at the far end spot, which should be single.Notice that the line doubles to give an upside down V whilst looking at the spot.The idea is to try and look at each spot in turn and see it as a single spot. If your eyes are converging correctly, the viewed dot will be seen singularly (but not necessarily clearly) and the other dots and line will appear to form an X.Try and bring your eyes in, and eventually to see the near spot singlyThis should be done gradually. DO NOT try and pull your eyes in to see the near spot first. Once you have reached the near spot and can maintain it as a single spot you will notice the line is now in a V pattern. Hold each spot for 20 seconds and repeat 4 times.

THANK YOU FOR YOUR ATTENTION