ABV 2 Midterm Review PDF

ABV 2 Midterm Review Hannah Grimes (423)-502-4432 [email protected] Table of contents 01 Hess Lancaster - Comitancy Part 1 02 Comitancy Part 2 03 Exotropia 04 Esotropia 01 Review of Hess Lancaster Hess Lancaster Test Two object method Assumes patient does not have AC or deep suppression You CANNOT assume a patient is strabismic or non-strabismic based on Hess Lancaster Setup: Patient in R/G Glasses Doc has red or green laser Patient has red or green laser (I’m not going to specify who has what because she can mix any of these scenarios on the exam) Results: Smaller enclosure = affected eye Larger enclosure = OA muscle (due to Hering's law) Hess Lancaster Test - Important Concept Whatever ﬁlter matches the light you (patient) are holding is the eye being tested. Whatever ﬁlter matches the light the doctor is holding is the eye that’s ﬁxating Example: Patient has green laser, doc has red. Red is over Right eye. ○ This means the RIGHT Eye IS FIXATING Hess Lancaster Test - Practice Hess Lancaster Test - Practice Answer: UA RLR Hess Lancaster Test - Practice Hess Lancaster Test - Practice Answer: UA RSO Red Lens Test Makes patient aware of pathological diplopia Direction of the deviated eye’s target is perceived in the opposite direction to the actual deviation Assumes patient does not have anomalous correspondence or deep suppression Setup: ○ Red lens over normal eye ○ Fixate penlight ○ Make sure patient sees red/white light in primary gaze ○ Move penlight into all 9 directions of gaze to ﬁnd where the lights are the MOST separated ○ Determine which image is projected further into this direction of gaze → pinpoints underacting eye Red Lens Test Which muscle is aﬀected? Red Lens Test Which muscle is aﬀected? UA RSO Red Lens Test Which muscle is aﬀected? Red Lens Test Which muscle is aﬀected? RLR 02 Comitancy Part 2 Non-Comitant Deviations Consecutive Strabismus When the deviation differs in direction from that of a pre-existing strabismus; usually post-surgical Prevalence: 4-20% Usually due to poor sensory fusion or anomalous correspondence prior to surgery Consecutive Consecutive ET XT Results from surgical correction of an XT “Used to be an ET but now they’re an XT” “Used to be XT but now they’re ET” Occurs spontaneously or more commonly Reported in children following surgical as a result of surgical correction of an ET correction of an intermittent XT in which 4-20% of all cases of ET treated surgically all children had HIGH AC/A Ratios (DIVERGENCE EXCESS) Consecutive XT What are the risk factors for developing Consecutive XT? ○ Groves Study → relationship between high hyperopia and consecutive XT Patients with ET wearing hyperopic correction > 7D eventually developed XT Occurs in 10-20% of ET patients treated with hyperopic glasses Mean interval of appearance of XT was 20.5 months (≈ 2 years) This does NOT occur in individuals with totally accommodative ET with normal binocular vision potential Why? Because glasses should FIX the accommodative issue and resolve the tropia Moderately sized ET with 4.5 D or more of hyperopia presents a risk factor for the development of consecutive XT Dissociated Vertical Deviation (DVD) A DEFINITE MUST KNOW Also known as an alternating hyperphoria Spontaneous turning of one eye or both eyes upward when the patient is fatigued, inattentive, or when fusion is interrupted (i.e. by covering an eye) So what do we see on cover test? ○ The eyes will drop down SLOWLY when ﬁrst uncovered Associated with infantile ET (appears around 2-3 years of age) YOU CANNOT NEUTRALIZE THIS WITH PRISM. DO NOT GET TRICKED BY THIS. PRISM IS NOT A TREATMENT OPTION Dissociated Vertical Deviation (DVD) How do we differentiate this from a real vertical deviation? ○ Vertical Phorias on cover test will have equal and opposite reactions between eyes One will go up and the other will go down ○ The eyes will also drop down QUICKLY whereas DVDs often have a slow return ○ DVDs are often ASYMMETRIC while real vertical deviations are SYMMETRIC How do we differentiate from an OAIO (a common differential)? ○ Hypertropia only happens in RIGHT or LEFT GAZE with an OAIO ○ No vertical deviation in primary gaze DVD Vertical OAIO Phoria Dissociated Vertical Deviation (DVD) Red Lens Test ○ The eye with the RED ﬁlter on it will deviate UP and see the IMAGE LOWER!!! In this example, red lens is over the RIGHT eye, the eye deviates up, and the image is seen lower Overacting Inferior Oblique (OAIO) Seen as a right hypertropia on left gaze and a left hypertropia on right gaze - when the eye is adducted THERE IS TYPICALLY NO DEVIATION IN PRIMARY GAZE!!!! Commonly associated with infantile onset ET DDX: ○ DVD ○ Secondary OAIO due to SO paresis in ipsilateral eye ○ Secondary OAIO due to SR paresis in contralateral eye (RARE) Overacting Superior Oblique (OASO) LESS FREQUENT THAN OAIO Usually coexists with ET or XT, but MORE COMMON in LARGE ANGLE XTs Bilateral >>> Unilateral USUALLY CAUSES AN A-PATTERN DEVIATION!!!!!!!!! Can also be associated with neurologic dysfunction - send for further testing OAIO + OASO Rare to have all 4 overacting CAUSES X-PATTERN DEVIATION More likely to happen in a large, long-standing, constant XT Pattern Strabismus (A-V) 30% of patients with strabismus may have an associated A or V component V ESO >>> A ESO >>> V EXO >>> A EXO X and Y pattern deviations are extremely rare Asthenopia is often associated with V-Eso and A-Exo Pattern Strabismus (A-V) Helpful hints for remembering this: Exotropia - eyes are OUT… where are the ends of the letter FURTHEST APART? Esotropia, eyes are IN, where does the letter meet at a point? Paretic vs Non-Paretic Strabismus If a non-comitant strabismus is of RECENT ONSET - RED FLAG If a deviation is long-standing or congenital, the patient is at low risk RUTH AND YOUNGE INCIDENCE OF NERVE PARESIS ○ CN VI - 42% ○ CN III - 29% (SR > IR = MR > IO) ○ CN IV - 17% ○ Multiple - 12% Paretic vs Non-Paretic Strabismus Must Know These Tables: Paretic vs Non-Paretic Strabismus Must Know These Tables: Stages of Recent Paresis Stage 1: Weakness of paretic muscle, followed by the OVERACTION of its DIRECT ANTAGONIST ○ Maximum deviation is still seen in the diagnostic action ﬁeld of the paretic muscle Stage 2: Contracture of the DIRECT ANTAGONIST ○ Contracture = increased resistance against passive stretching ○ This happens because this muscle is CONSTANTLY overacting trying to compensate for the paresis and eventually it loses elasticity Stage 3: Deviation spreads into all ﬁelds of gaze and becomes increasingly comitant (spreading of comitancy) Complete CN III Paresis Presents with an eye which is abducted, hypotropic and intorted with a ptosis and ﬁxed dilated pupil ○ AKA an eye that’s down and out, with a large, unresponsive pupil, and a droopy lid When do we we worry less? When the patient is > 50 y/o and has a Dx of Diabetes - this is a complication of diabetes. ○ Will usually clear up in 6-8 weeks ○ Refer to internist Causes: Undetermined > Vascular > Head Trauma > Aneurysm > Neoplasm > Other (Rush and Younge) Superior Rectus Paresis Hypo deviation of the affected eye with limitation of elevation when the eye is abducted Isolated SR paresis = RARE ○ Commonly congenital SR paresis is often associated with levator palpebrae weakness resulting in a pseudo-ptosis DDX: mechanical limitations, Thyroid myopathy ○ IMSLOw Medial Rectus Paresis Limitation or absence of ADDUCTION XT in primary gaze Face turned toward affected ﬁeld, NOT THE AFFECTED EYE Isolated MR paresis = RARE ○ Commonly congenital DDX (IMPORTANT TO KNOW) Internuclear ophthalmoplegia (INO) - adduction is absent but CONVERGENCE is intact Unilateral - basilar artery infarct BIlateral - PATHOGNOMONIC OF MS!!! Inferior Rectus Paresis Limitation or absence of depression when the eye is abducted and a probably hyperdeviation Isolated IR paresis is rare and most commonly congenital Patients usually present with a depressed chin, head tilted toward the affected ﬁeld Inferior Oblique Paresis Patient presents with an inability to elevate the eye when adducted, probably hypo-deviation in primary gaze Isolated IO paresis is rare; this muscle is the LEAST LIKELY of all muscles to be paretic and most commonly congenital Chin is elevated and head is tilted toward the affected ﬁeld DDx: Brown’s Syndrome CN4 Paresis (SO) Patient presents with a hypertropia of the affected eye and an inability to depress the eye when adducted The chin is usually depressed and head is tilted AWAY from the affected side Etiology (Rush and Younge) - ADULTS ○ 36% - undetermined ○ 32% - head trauma ○ 18.6% - vascular ○ 4.1% - neoplasm ○ 1.7% - aneurysm ○ 7.6% - other Etiology in Children ○ 60% - congenital ○ 35% - head trauma ○ 5% - inflammation CN6 Paresis (LR) Patient presents with limitation of abduction, probably ET in primary gaze and a face turn toward the involved side Lengthy course through the skull makes CN6 vulnerable to extensive variety of disease process Etiology (Rush and Younge) - Adults ○ 29.6% - undetermined ○ 17.7% - vascular ○ 16.7% - head trauma ○ 14.6% - neoplasm ○ 3.6% - aneurysm ○ 17.4% - other Children ○ 40% - neoplasm; always send for imaging if you see a CN6 palsy in a child ○ 20% - trauma ○ 17% - inflammation ○ 29% - other ○ 9% - undetermined CN6 Paresis (LR) Differential Diagnoses ○ Duane’s Syndrome ○ Cross Fixation ○ Transient Newborn CN6 paresis (usually resolves by 6 weeks) ○ Painless acquired CN6 paresis (1-3 weeks following febrile illness - recovery usually within 10 weeks) ○ Nystagmus compensation (Blockage) Syndrome Multiple Nerve Palsies Neoplasm = most frequent cause Location in Cavernous Sinus or Superior Orbital Fissure where multiple nerves lie in close proximity (III, IV, V1, V2, VI) Duane’s Retraction Syndrome Most frequent presentation = marked limitation or absence of abduction, slight restriction of adduction, retraction of the globe and narrowing of the palpebral ﬁssure on adduction (AKA DUANE’S TYPE 1) More frequently involves the LEFT EYE and is more common among females 30-40% of patients have associated congenital defects involving ocular, skeletal or neural structures Etiology: ○ Neurogenic disorder involving either a supranuclear lesion or a cranial nerve anomaly in which branches of CN3 innervate the LR ○ Retraction of the globe → caused by co-contraction of MR/LR Duane’s Retraction Syndrome Duane’s mimics CN6 paresis, but with Duane’s most patients are binocular in primary gaze; sometimes they present with a slight head turn Categorization of Duane’s Syndrome Type 1: limitation of abduction Type 2: limited or absent adduction with relatively normal abduction Type 3: presents as limited or absent abduction and adduction (rare) DDx: VI nerve paresis Brown’s Syndrome Also known as SO Tendon Sheath Syndrome Patient usually presents with an absence of elevation when the eye is adducted The patient will show a (+) Forced Duction Test (eye doesn’t move with force) Normal or near normal elevation is seen in primary gaze and abduction This mimics an IO paresis, but IO rarely happens in isolation - 3rd nerve is usually the cause, which will affect more than just the IO. Endocrine Myopathy Graves Disease → limitation of ocular mobility ○ Presents with insidious onset of diplopia related to onset of exophthalmos and limitation of elevation associated with retraction of the upper lid (+) Forced Duction Test Refer to internist Fractures of the Orbit Patient may present with marked swelling ecchymosis of lids, epistaxis (nose bleeds) or hx of these signs May see marked limitation of eye movements - elevation is often affected speciﬁcally (entrapment of IR and possibly SO) → blowout fracture Diplopia on upgaze (+) Forced Duction Test If the trauma is recent, rule out restriction caused by temporary congestion of orbital contents - diplopia should resolve in a few days SEND FOR X-RAY Myasthenia Gravis Weakness of voluntary muscles (facial, mastication, swallowing, oculomotor) Ocular muscle involvement occurs in 90% of cases and is the initial complaint in 75% of patients Ptosis usually presents ﬁrst with easy muscle fatigue and rapid relief with Tensilon test Commonly affects females in 20s Look for associated limb weakness and difﬁculty swallowing, symptoms increasing with exercise or as the day passes Practice Questions Q1: What AC/A Ratio is almost always found in children with consecutive ET? ○ a) High ○ b) Low ○ c) Normal Q2: True or false: consecutive XT is a common occurrence in patients with accommodative ET Q3: How much hyperopia puts a patient at risk for the development of consecutive XT? Practice Questions Q4: Which of the following is NOT a characteristic of DVD? ○ a) Associated commonly with infantile ET ○ b) Both eyes will drop down slowly after being uncovered on cover test ○ c) Easily neutralized with prism ○ d) Usually an asymmetric deviation between eyes Q5: When performing a red lens test on a patient with DVD, if the lens is placed over the right eye, describe what position the eye is in and where the image position is. Q6: You’re performing cover test on a patient. On ACT, you observe the right eye drop down, and the left eye move up. You attempt this in left gaze and right gaze and observe the same movement. What is your diagnosis? ○ a) DVD ○ b) OAIO ○ c) OASO ○ d) RHP Practice Questions Q7: True or false: In a patient with OAIO, primary gaze typically shows little to no deviation Q8: You’re performing cover test on a patient. When in primary gaze, you observe a slight outward movement of both eyes. You repeat cover test in left gaze and right gaze. When in left gaze, the right eye moves downward. In right gaze, the left eye moves downward. What is your diagnosis? ○ a) DVD ○ b) OAIO ○ c) OASO ○ d) RHP Q9: Which of the following is not commonly associated with infantile ET? ○ a) OASO ○ b) OAIO ○ c) DVD ○ d) Nystagmus Practice Questions Q10: Which of the following is true regarding OASO? ○ a) More commonly unilateral ○ b) Causes an A pattern deviation ○ c) Common with large angle ET ○ d) If combined with an OAIO, it can result in a Y Pattern deviation Q11: Which of the following is the most common pattern strabismus? ○ a) V Exo ○ b) A Exo ○ c) V Eso ○ d) A Eso Q12: Q11: Which two of the following are most associated with asthenopic complaints? ○ a) V Exo ○ b) A Exo ○ c) V Eso ○ d) A Eso Practice Questions Q13: According to Rush and Younge, which of the following is the most common nerve paresis? ○ a) CN III ○ b) CN IV ○ c) CN V ○ d) CN VI Q14: Which of the following is NOT a characteristic of a paretic strabismus? ○ a) Past Pointing ○ b) Diplopia ○ c) Amblyopia ○ d) Lack of adaptations Q15: Which of the following is a false regarding a recent paresis? ○ a) Patients present with a head posture that remains when covering the paretic eye ○ b) Patients present with facial symmetry ○ c) Image Tilting is often present ○ d) No contracture of the antagonist w/Forced Duction Practice Questions Q16: Which of the following is FALSE regarding a recent paresis? ○ a) Overaction of the direct antagonist ○ b) Maximum deviation is noted in the diagnostic ﬁeld of gaze ○ c) Spreading of comitancy the longer the paralysis lasts ○ d) Contracture of the paretic muscle Q17: Which of the following is not characteristic of a CN III Paresis? ○ a) Abduction of the eye ○ b) Depression of the eye ○ c) ﬁxed, miotic pupil ○ d) lid ptosis Q18: You have a patient in your chair with an eye that’s deviated slightly outward. You perform EOMs and note that the eye cannot adduct.You perform NPC and the patient is able to achieve TTN. What is your diagnosis? ○ a) Paretic MR due to infarct of a basilar artery ○ b) Internuclear Ophthalmoplegia ○ c) Paretic MR due to MS ○ d) Brown’s Syndrome Practice Questions Q19: Which of the following is expected with an IR paresis? ○ a) eye is unable to depress when abducted ○ b) eye is unable to elevate when abducted ○ c) eye is unable to depress when adducted ○ d) eye is unable to elevate when abducted Q20: Out of all the EOMs, which of the following is least likely to be paralyzed? ○ a) SR ○ b) IR ○ c) LR ○ d) MR ○ e) SO ○ f) IO Practice Questions Q21: Which of the following head positions is characteristic of a SO paresis? ○ a) Chin tilted up, head tilted toward affected ﬁeld ○ b) Chin tilted down, head tilted toward affected ﬁeld ○ c) Chin tilted up, head tilted away from affected ﬁeld ○ d) Chin tilted down, head tilted away from affected ﬁeld Q22: According to Rush and Younge, what is the most common cause of lateral rectus paralysis in children? ○ a) vascular ○ b) neoplasm ○ c) trauma ○ d) inflammation Q23: You have a patient with a LLR paresis. Which of the following head positions would you most likely observe? ○ a) head tilt left ○ b) head tilt right ○ c) head turn left ○ d) head turn right Practice Questions Q24: You’re testing EOMs on a young female patient. When testing, you move your penlight left and notice the patient’s right eye does not abduct. You also notice a slight narrowing of the palpebral ﬁssure. When you move your penlight directly to the right, both eyes move to the proper position. What would you diagnose this patient with? ○ a) Brown’s Syndrome ○ b) Duane's Type I ○ c) Duane’s Type II ○ d) Duane’s Type III ○ e) INO Q25: Which of the following does not have a (+) Forced Duction Test ○ a) Duane’s Syndrome ○ b) Brown’s Syndrome ○ c) Endocrine Myopathy ○ d) Orbital Blowout Fracture Practice Questions Q26: You have a patient in your chair complaining of double vision on occasion. You take a look at her in your chair and her eyes are both aligned. Cover test reveals nothing besides a small phoria. Vergence ranges are normal and accommodation is also normal. You perform EOMs and notice that the right eye refuses to elevate on adduction. Elevation on abduction is normal in the right eye. What condition do you suspect? ○ a) OASO ○ b) OAIO ○ c) Duane’s Type II ○ d) Brown’s Syndrome ○ e) Endocrine myopathy Q27: You have a patient come in for an OV complaining of double vision. She tells you that she notices it most when running on the treadmill at the gym. She says the numbers go double when she’s trying to read her mileage. She claims that she has no trouble with reading and computer work and has only noticed this issue at the gym or sometimes a little when she’s really tired. She does not wear glasses. What issue do you suspect? ○ a) Brown’s Syndrome ○ b) Duane’s Type II ○ c) Endocrine Myopathy ○ d) Myasthenia Gravis 03 Exotropia Classiﬁcations of XT Constant XT Basic Exo Deviation(BXT) Infantile (congenital) Normal AC/A Ratio Secondary XT Near and far 5∆ CI (you’ll often catch the patient winking an eye Basic XT closed in the sun) DE Convergence Insufﬁciency (CIXT) Low AC/A Ratio Exo is larger at near than far by > 5∆ Infantile XT Often associated with neurological syndromes Onset before 6 months or 1 year of age Deviation ○ Large, constant or alternating ○ Magnitude ranges from 30-80∆ (mean of 50∆) Often has a DVD Normal refractive error No amblyopia (usually) Latent nystagmus is UNCOMMON May only use abducting eye to ﬁxate and not adduct either eye Potential for obtaining normal, single BV after treatment is POOR Suppression and Anomalous Correspondence is COMMON Secondary Exotropia - Sensory Constant, unilateral XT following the loss or severe reduction of vision in one eye Usually caused by pathology Deviation is usually large (30-60∆) Occurs with almost equal frequency as sensory ET when onset is between birth-5 Older children/adults SENSORY XT > SENSORY ET (due to reduced tonic convergence) Early onset → reduced potential for normal BV Prolonged sensory deprivation may result in central fusion disruption and intractable diplopia Secondary Exotropia - Consecutive XT Remember how we just talked about this? It’s BAAAAAaaaaack. Constant XT that was preceded by ET Occurs either spontaneously or over time following surgery for ET Prevalence of consecutive XT reported to occur in as many as 10-20% of ET patients treated with hyperopic glasses → Don’t forget the risk factors we discussed before ○ > 4.50 D of hyperopia + moderate sized ET ○ Occurs around 20.5 months of age Paretic XT Caused by mechanical restriction or paresis of EOMs ○ CN3 paresis - isolated MR paresis (super uncommon) ○ Ocular myasthenia ○ Thyroid myopathy (IMSLOw) ○ Trauma ○ Duane’s type 2 (can’t ADduct) Decompensated XP or Intermittent XT Large XP ⇒ Decompensation ⇒ Intermittent XT ○ Your system can hold it together some of the time, but not all Intermittent XT ⇒ Decompensation ⇒ Constant XT ○ Rare (4%) Most XT that isn’t infantile, secondary or associated with paresis or mechanical restriction of an EOM will be intermittent Convergence Insufficiency Onset is variable; usually discovered because of asthenopic complaints from school-aged children Near Deviation >>> Far Deviation Usually XP, sometimes intermittent XT REDUCED NPC REDUCED PFV Accommodative Issues are Common ○ Reduced AMPS ○ LAG of accommodation ○ Reduced Facility Convergence Insufficiency Patients can often achieve STEREOPSIS, but it may not be stable (unstable 2º fusion on up) Intermittent suppression is common LOW INCIDENCE OF AMBLYOPIA? ○ Why? Both eyes are working together most of the time; this occurs more when the system tires out MOST HAVE NORMAL CORRESPONDENCE Basic Exo Regular AC/A Onset is intermittent; half onset within the 1st year of life Characteristics ○ Same magnitude of deviation at near and far ○ HOWEVER patients may be phoric at near and trope at distance ○ Intermittent frequency (often higher at distance) ○ Good stereo, but sometimes trouble with 2º fusion, just like the CIXT ○ No amblyopia ○ Receded NPC ○ Insufﬁcient PFV Covariation Often called “the best case scenario” Patient is NC when aligned, but HAC when deviated ○ You’re using the fovea and an anomalous point ○ This is an EASY ﬁx because the fovea already is in use; we just have to train to not use that HAC point ○ Chance of being bifoveal is EXCELLENT! Divergence Excess Variable onset PHOTOPHOBIA IS A COMMON SIGN; patients wink an eye shut in the sunlight Characteristics Pt is usually phoric at near Constant or intermittent tropia at far ○ Triggered by mechanisms related to: Inattention Distance viewing Fatigue Illness Daydreaming Amblyopia is ABSENT Patient may co-vary DE vs PSEUDO-DE 60-90% of DE cases are actually PSEUDO-DE Patients with pseudo-DE will have a LOW AC/A instead of a HIGH AC/A Do either the Occlusion Test or the +3.00D lens test (MUST KNOW) Occlusion Test Unilateral occlusion (30-45 mins) ○ PDE: ↑ near deviation ○ True DE: no effect +3.00D Lens Test True DE: ↑ in the near deviation PDE: no signiﬁcant increase in near deviation Intermittent XT Control Scale Practice Questions Q28: Which of the following is NOT a characteristic of Infantile XT? ○ a) Often occurs with a DVD ○ b) No amblyopia present ○ c) Nystagmus common ○ d) Anomalous Correspondence is common ○ e) Poor Tx outcome Q29: Which of the following statements is true regarding Sensory Exotropia? ○ a) Occurs at equal frequency as sensory ET when onset between birth - 5 y/o ○ b) Deviation is usually small angle (5-10∆) ○ c) In older children (5+), sensory ET occurs more frequently than sensory XT ○ d) Usually caused by pathologies Q30: Which of the following is not a cause of a Paretic XT? ○ a) CN III paresis ○ b) Thyroid Myopathy ○ c) Duane’s Type I ○ b ) Ocular Myasthenia Practice Questions Q31: Which of the following is NOT related to Convergence Insufﬁciency? ○ a) Reduced NPC ○ b) Reduced PFV ○ c) Anomalous Correspondence ○ d) Trouble with 2º fusion Q32: True or false: Covariation occurs when the patient has normal correspondence when aligned, but Harmonious Anomalous Correspondence when deviated. Q33: Which deviation is most commonly associated with Covariation? ○ a) CI ○ b) Basic Exo ○ c)CE ○ d) Basic Eso ○ e) DE ○ f) DI Practice Questions Q34: What results would you expect on a +3.00 D lens test for a true DE? ○ a) signiﬁcant decrease in the near deviation ○ b) signiﬁcant increase in the near deviation ○ c) no signiﬁcant increase/change in the near deviation Q35: What would you see in a patient with an IXT with a control scale of 1? ○ a) No exotropia unless dissociated, Recovers in < 1 second ○ b) Exotropia > 50% of the exam before association ○ c) No exotropia unless dissociated, recovers between 1 and 5 seconds ○ d) Exotropia < 50% of the exam before dissociation ○ e) No exotropia unless dissociated, recovers in > 5 seconds 04 Esotropia Classiﬁcations Infantile ET Basic ET Classically considered non-accommodative Normal AC/A Ratio Divergence Insufﬁciency Acquired ET Low AC/A Ratio a) Accommodative ET Esodeviation larger at far than near by >5∆ ○ Refractive (Normal AC/A) ○ Non-Refractive (High AC/A) ○ Combination Other Types of ET b) Partially Accommodative ET Small angle ET c) Non-accommodative ET ○ Microtropia (von Noorden) ○ Monoﬁxation Syndrome (Parks) Secondary ET Convergence Excess Blind-Spot ET High AC/A Cyclic ET Esodeviation larger at NEAR than at far by > Paretic ET 5∆ Infantile ET Prevalence: 28% - 54% of all ETs Familial tendency Caused by an innervational issue Onset Onset usually around 3-4 months of age (birth to 6 months or 1 year) Acute onset, constant strabismus Deviation Large, relatively stable angle (30-60 ∆) Equal at far and near (not an AC/A situation and not due to accommodation) Rarely less than 30∆ but this isn’t a hard and fast rule Usually constant, alternating strabismus with normal AC/A Infantile ET PEDIG Studies (2002) changed our original thoughts about infantile ET ○ More variation in ET size that previously thought Around 50% are ≥ 40 ∆ Most of the larger deviations were constant Most of the smaller deviations were intermittent or variable ○ Deviation is not always constant 56% constant 25% variable 19% intermittent Infantile ET Refractive Status ○ Infantile ET is considered NON-ACCOMMODATIVE ○ Usually the patient has an insigniﬁcant refractive error Most have low-moderate hyperopia ○ Correction will not have much effect on the magnitude of the deviation Ocular motility ○ Apparent defective abduction defect (pseudo VI nerve paresis) called Cross Fixation Pattern (right eye views left VF, left eye views right VF; alternates the eye in use and protects from amblyopia) DDx: CN6 paresis, Duane’s, Nystagmus Blockage Syndrome ○ Primary OAIOs - onset ≈ 2 yrs DDx: DVD, primary CN IV paresis ○ DVD (onset ≈ 2 years) Incidence: 75-90% DDx: OAIO ○ Latent Nystagmus Infantile ET Visual Acuity ○ Amblyopia incidence is 19% ○ IT IS RARE TO HAVE AMBLYOPIA IF THE PATIENT CROSS FIXATES!!!!!!! Correspondence ○ High percentage of anomalous correspondence (AC) ○ “Lack of correspondence” is found when evaluated later in life Clinical Features of Infantile ET*** ○ OAIOs ○ Nystagmus ○ DVD ○ Amblyopia ○ Limited potential for normal BV Accommodative ET Onset: ○ Between Birth and 7 y/o Most commonly between 2.5-3 years (basically when the child is starting to be interested in looking at picture books ○ Type of Onset: Intermittent/Gradual Visual Acuity ○ Seldom amblyopia; depends on frequency and presence of aniso Correspondence: USUALLY NORMAL CORRESPONDENCE Two Subcategories: Refractive Accommodative Non-Refractive Accommodative Refractive Accommodative ET Mechanism: UC Hyperopia with normal AC/A but insufﬁcient divergence ability ○ Note: WILL NOT BE A MYOPE; could be an astigmat but rare Refractive Error: mean +4.50 (+2.00 to +7.00) Deviation: ○ Moderate, variable: 20-40∆ ○ Equal at near and far ○ Intermittent Strabismus Non-Refractive Accommodative ET Mechanism: High AC/A with insufﬁcient divergence ability Refractive Error: Low Hyperopia (Mean +2.25, range +0.50 to +4.50) ○ NOTE: MYOPIA CAN OCCUR WITH THIS ONE (myope + high AC/A + ET at near) Deviation: ○ Moderate, variable ○ Greater at near ○ Can be constant at near At a Glance Refractive Non-Refractive Accommodative Accommodative AC/A Normal High Refractive Error +4.50 AVG (+2.00 to +7.00) +2.25 AVG (+0.50 to +4.50) Deviation Variable, moderate Variable, moderate Equal at NEAR AND FAR Greater at NEAR Frequency Intermittent (usually) Constant at near Remember: these are not mutually exclusive. YOU CAN HAVE A COMBINATION!!! Part of the ET is due to uncorrected hyperopia, and part is due to high AC/A If the deviation is fully ACCOMMODATIVE, then glasses will ﬁx the entire issue (whether it’s SV, a bifocal, etc). If there is some left over after refractive correction (OR glasses do nothing to change the deviation), then there is a non-accommodative component! Partially Accommodative ET Onset: Variable Refractive Status: ○ Variable ○ Residual ET AFTER FULL CORRECTION of ametropia Deviation: ○ Usually unilateral; may alternate ○ There is an accommodative component, but a residual angle remains after full (+) RX given ○ RESIDUAL DEVIATION TENDS TO BE CONSTANT Visual Acuity ○ Amblyopia is COMMON ○ EF COMMON Correspondence: AC >>> Non-Accommodative ET Onset: 3-6 years of age (LATER!!!) GLASSES/FULL (+)RX will have LITTLE TO NO EFFECT Magnitude ↑ as Age ↑ MUST RULE OUT UNDERLYING CNS LESIONS!! Acute Onset ET May be similar to a non-accommodative ET, but can still be a BRAIN TUMOR EVEN THOUGH IT IS COMITANT Can be the ﬁrst sign of CNS pathology Physical or emotional stress can sometimes be a precursor Clinical Characteristics: Onset: SUDDEN but can be variable or intermittent Angle is typically large (> 25∆) Refractive error is small AC/A is normal Acute Onset ET Diagnosis ○ MUST do an ocular motility exam to determine comitancy ○ Comitancy does not rule out underlying neurological diseases ○ THERE SHOULD NOT BE AMBLYOPIA, AC, OR SUPPRESSION IF RECENT ONSET Refer out if… ○ (+)HAs ○ Papilledema ○ APD ○ Unusual clumsiness ○ Inability for sensory fusion with prism or amblyoscope ○ Nystagmus that isn’t long standing (cyclorotary, pendular) Small Angle ET Microtropia ○ Unique form of strabismus - usually Esotropia w/Amblyopia - where UCT shows NO MOVEMENT, but visuoscopy shows eccentric ﬁxation Angle of Deviation (

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