Exotropia: Classification and Diagnosis PDF

Exotropia: Classification and Diagnosis Maureen Plaumann, OD, PhD Exotropia Types Fewer ways to classify exotropia Age of onset Relationship to Accommodation AC/A style Frequency Age of Onset Early Onset Infantile Exotropia Later Onset Sensory Exotro...

Exotropia: Classification and Diagnosis Maureen Plaumann, OD, PhD Exotropia Types Fewer ways to classify exotropia Age of onset Relationship to Accommodation AC/A style Frequency Age of Onset Early Onset Infantile Exotropia Later Onset Sensory Exotropia Consecutive Exotropia Decompensated Phoria AC/A Style Convergence Insufficiency Exotropia Basic Exotropia Divergence Excess Exotropia Pseudo-Divergence Excess Exotropia Frequency Constant Exotropia Intermittent Exotropia This is the one you will see the most often in practice! Age of Onset Early Onset Infantile Exotropia Later Onset Sensory Exotropia Consecutive Exotropia Decompensated Phoria Infantile Exotropia XT develops within first 6 months of life Recall: Alignment and oculomotor control is not rudimentarily established until 3 months Usually begins at age 2 to 5 months Prevalence: 0.1% of population (less common than Infantile ET) Infantile Exotropia Risk Factors Prematurity/low birth weight Neurodevelopmental Delays Prevalence Higher occurrence in patients of Asian and African descent Infantile Exotropia Features Large angle, constant exotropia (40-60pd, Distance and near) Typically normal AC/A If unilateral, remember to treat amblyopia Often with AC or dense suppression Infantile Exotropia Features (Continued) Overacting Inferior Obliques (OAIO) common Dissociated Vertical Deviation (DVD) common Latent or Manifest Nystagmus Generally comitant, though may have A/V pattern Can present with limited adduction May appear to be “bilateral” Sensory Exotropia Exotropia because of poor vision in one eye d/t disease Ex: cataract, corneal clouding, ONH disorders, retinal diseases More commonly XT when VA loss older (but not always) Poor binocular fusion because of poor vision in one eye Large angle XT though can be intermittent Note: Likely still impaired BV when fused Sensory XT – Mini Case 1 (Constant) 10 year-old boy Patching for 10 weeks, Wet Ret potential improvement in OD: +0.25 -0.50 x180 acuity (20/200, 20/250, OS: -3.00 -1.75 x180 20/150 x 2) Visual Acuity (cc) Unilateral optic nerve head OD: 20/20 hypoplasia OS OS: 20/150 Dense suppression OS Alignment (cc) No stereo CLXT (all distances) ONH hypoplasia OS – 10 yo boy with CLXT Sensory XT – Mini Case 2 (Intermittent) 6 year-old boy Wet Ret Had been started patching OD: +0.75 for “amblyopia” OS: +0.75 Unilateral vitreomacular Visual Acuity (cc) traction OS OD: 20/20 Stereo OS: 20/32 Global – 250” Local – 30” Alignment (cc) Variable frequency of tropia CLXT (distance) at near ILXT (near) Vitreomacular Traction – 6 yo boy with ILXT Consecutive XT Outward turn of eye s/p previous ET Often from strabismus surgery, can have consecutive XT after full plus for ET but can modify power of lenses to bring eye back in 12.5%-41% with treated infantile esotropia Surgeon dependent, many trained to over correct to help prevent drift back to original ET posture Onset at any age (possibility to spontaneously develop too) Decompensated Phoria Adults presenting with XT when previously been XP Often symptomatic as previously had normal BV “Pulling” sensation of eyes, headaches, diplopia, etc. Investigate with compensating prism to explore BV potential with treatment Unlikely to suppress or have AC AC/A Style Convergence Insufficiency Exotropia Basic Exotropia Divergence Excess Exotropia Pseudo-Divergence Excess Exotropia Convergence Insufficiency (CI) Exotropia Characterized by a Low AC/A Greater magnitude at near compared to distance Often have better control at DISTANCE than near Common signs Receded NPC, Low BO ranges at near, symptomatic on CISS Convergence Insufficiency (CI) Exotropia What distinguishes them from a typical Convergence Insufficiency? Doctor dependent Some will label with XT if they see any troping at near on exam Others only use XT label if also troping at distance with a bigger magnitude at near Basic Exotropia Characterized by a Normal AC/A Similar magnitude at near and distance Often have better control at NEAR than distance Common signs Potential for receded NPC, low BO ranges at distance and near, may have symptoms or may be suppressing Divergence Excess (DE) Exotropia Characterized by a High AC/A Greater magnitude at distance compared to near Often have better control at NEAR than distance Common signs Potential for receded NPC, low BO ranges at distance and near, may have symptoms or may be suppressing Pseudo-Divergence Excess Exotropia Appear to have a larger deviation at distance compared to near but are truly more equal in magnitude Really are Basic XT but present as Divergence Excess XT Common signs (same as Basic or DE) Potential for receded NPC, low BO ranges at distance and near, may have symptoms or may be suppressing Pseudo-DE versus True DE Pseudo-DE more common than True DE How to tell them apart? Occlusion Method Lens Method Pseudo-DE versus True DE – Occlusion Prolonged occlusion of one eye (30-60 min) May have patient present for follow-up appointment patched Do not let patient fuse! Perform ACT and look at magnitude at near If it has increased, then patient is Pseudo-DE Distance and near magnitudes more equal, really a Basic XT Pseudo-DE versus True DE – Lenses Repeat ACT at near (33cm) with +3.00 lenses Perform ACT and look at magnitude at near If it has increased significantly, then patient is Truly DE Demonstrating their High AC/A ratio with big change to lenses Pseudo versus True DE – Example 1 Patient 1 Distance: 40BI, Near: 20BI After 30 min occlusion, Near: 20BI Diagnosis? Pseudo versus True DE – Example 2 Patient 2 Distance: 40BI, Near: 20BI After 30 min occlusion, Near: 40BI Diagnosis? Pseudo versus True DE – Example 3 Patient 3 Distance: 30BI, Near: 10BI Repeat through +3.00, Near: 40BI Diagnosis? Pseudo versus True DE – Example 4 Patient 4 Distance: 30BI, Near: 10BI Repeat through +3.00, Near: 15BI Diagnosis? Pseudo versus True DE – Why Care? May not always complete testing to differentiate between the two, depending on symptoms and patients' preference for treatment Vision therapy and prism less likely to depend on true angles, but surgical intervention will be impacted Frequency Constant Exotropia Intermittent Exotropia This is the one you will see the most often in practice! Frequency Constant Intermittent Infantile Sensory (potentially) Sensory (more likely) Decompensated Phoria Consecutive Childhood-onset Intermittent Exotropia  Intermittent Exotropia (IXT) – Background Childhood Onset Approximately 25% of all childhood strabismus Noticeable eye turn when misaligned with ability to fuse at certain distances/times *Govindan et al 2005  IXT – Signs Lack of symptoms (typically) Monocular eye closure in bright sunlight Cosmetically noticeable Suppression or AC (Covariation) Recall: Not amblyogenic, but anisometropic amblyopes may present with IXT *Lew et al 2007 IXT – Case History Identify motivation for treatment (if any) Younger patients, parents more likely to care Older patients, patient more likely to care Identify symptoms, if present (more likely in CIs “gone bad”) Get history of treatment IXT – Work-up Motor Sensory Cover Test (Distance/Near) Stereopsis Control Score Expect to find at near Can also perform at distance NPC Worth 4 Dot Vergence Ranges (if fused) HBAIT Vertical? Are they suppressors or are May be a primary or they covary-ers? secondary vertical  IXT – Control Score Protocolized method to standardize control of XT Starts with observation periods at distance and near *Mohney and Holmes 2006 IXT – Control Score Example 1 Control Score: 3. Observable tropia < 50% of the time IXT – Control Score Example 2 No observable tropia over 30 seconds Control Score will be 5 seconds Control Score: 2 If recovery time < 5 seconds, proceed with testing (up to 2 more covers left to perform) IXT – Control Score Tips When meeting a new patient, it can be hard to identify tropia without dissociating After both 30 second observation trials, okay to go back and cover at distance Will either begin the 3 trials to differentiate Score 0-2 OR Will confirm patient was out the whole time and Score = 5  IXT – Control Score 30 second observations Cover for 10 seconds (only after completing both observations!) 50% and 5 seconds help to differentiate each category *Mohney and Holmes 2006 IXT – Work-up Motor Sensory Cover Test (Distance/Near) Stereopsis Control Score Expect to find at near Can also perform at distance NPC Worth 4 Dot Vergence Ranges (if fused) HBAIT Vertical? Are they suppressors or are May be a primary or they covary-ers? secondary vertical Primary or Secondary Vertical You see vertical movement on your IXT patient’s cover test Is the eye moving vertically SOLELY because of the horizontal misalignment (secondary) OR Is the eye moving vertically because your patient has a “true” vertical deviation (primary) Primary or Secondary Vertical You see vertical movement on your IXT patient’s cover test Is the eye vertically displaced SOLELY because your patient is dissociated (secondary) OR Is the eye vertically displaced because your patient has an associated vertical deviation (primary) Test to differentiate: Wesson Card (Associated Phoria testing) Wesson Card for Verticals Turn sideways to look for associated vertical If arrow not pointing at red line, align with appropriate prism and record associated vertical phoria If arrow aligned, consider flip prism testing to look for a preference E.g. Still lined up with 1BDOD but then arrow misaligned with 1BUOD, has a small right hyper bias May not be able to perform if patient troping at near Primary or Secondary Vertical If your patient reports misalignment on Wesson card, then they have a PRIMARY vertical deviation If your patient reports aligned on Wesson card, but you see movement on cover test, that is a SECONDARY vertical deviation Primary verticals benefit from vertical prism in glasses Do not confuse with comitancy primary versus secondary!  Distance Stereo Test https://www.stereooptical.com/products/stereotests-color-tests/distance-randot/ HBAIT Review Recall, Covariation of Correspondence will have patients alternate between NORMAL correspondence and HARMONIOUS anomalous correspondence NC when aligned, HAC when deviated Will have UNCROSSED after images IXT – Parent Education Variety of treatment options exist Active monitoring, overminus lenses, part-time patching, prism, vision therapy, surgery Often, patient has good binocularity potential, just little to no awareness when they do not Treat symptoms if present (child complaining) IXT – Is it okay to wait? Low progression from IXT to Constant XT over 3 year period In 1-3 year-olds: 10% converted to “constant” In 3-10 year-olds: 15% converted to “constant” Constant XT determined based on 1 control score with same day retest for both groups OR drop in stereo for older group, even if later they regained stereo at future visits  IXT 2 Findings – Younger Cohort 1-3 year-olds Deterioration Criteria Control Score = 5 Treatment implemented *Cotter et al 2020  IXT 2 Findings – Older Cohort 3-10 year-olds Deterioration Criteria Control Score = 5 Stereo drop by 2 octaves *Mohney 2019 IXT – Is it okay to wait? Is it okay to wait? Most in optometry would say: Yes! Some in ophthalmology agree What’s the concern with rushing to surgery? May take an intermittent fuser with stereo and convert them to constant small angle ET with no stereo