Dissociated Vertical Deviation

Etiology

The etiology of dissociated vertical deviation is not known. A few of the important points to consider include:

• An elastic preponderance of the elevator or depressor muscles, which imbalances the amount of innervation from each vestibular organ
• Abnormalities of the visual pathway
• Imbalance of binocular stimulation [3]

DVD is a unique ocular motility disorder, typically associated with early-onset strabismus, particularly infantile esotropia (see Tables 1 and 2). The etiology remains multifactorial and not fully understood, but several mechanisms have been proposed:

• Sensory theory (binocular maldevelopment):
• DVD is thought to arise from disrupting normal binocular development during infancy.
• Early loss of fusion (due to strabismus, anisometropia, or amblyopia) leads to defective cortical binocular interactions.
• This results in a dissociated response where one eye drifts upward when not fixating, independent of the Hering law.[13]
• Motor theory (vestibular imbalance):
• An imbalance in vertical vergence or vestibular pathways has been implicated.
• Bielschowsky suggested that latent nystagmus and abnormal vertical vergence mechanisms are linked.[14]
• Abnormal vertical vergence pathways:
• Some evidence suggests that DVD may represent an abnormal adaptive mechanism to suppress diplopia and confusion by elevating the nonfixing eye.
• This is thought to involve supranuclear control pathways for vertical vergence.[15]
• Neurophysiological basis:
• DVD is considered part of humans' “dorsal light reflex” abnormality, resembling compensatory eye movements in animals with binocular disruption.
• Functional MRI and electrophysiology studies support the role of subcortical (brainstem/vestibular) mechanisms.[12]
• Association with strabismus and amblyopia:
• Most cases occur in children with infantile esotropia, amblyopia, or other early binocular sensory deficits.
• DVD is rare in patients with normal binocular development.[16]

 Table 1. Theories of DVD Etiology

 Table 2. Clinical Associations of DVD

The etiology of DVD is multifactorial, with early sensory disruption of binocular vision considered the most widely accepted mechanism, possibly modulated by vestibular/vertical vergence pathway abnormalities. Associations with infantile esotropia, amblyopia, and latent nystagmus provide strong clinical support for these theories.[17]

Epidemiology

In the United States, about 3% to 5% of children have strabismus. The prevalence of DVD among the diagnosed cases of strabismus was estimated at 1.9%.[18] was found to be more frequently associated with sensory esotropia than exotropia.[19] Kutluk et al reported a DVD prevalence of 12.5% in patients with sensory hypertropia (see Image. Exotropia (20 degrees) and Hypertropia (10 degrees), Left Eye).[19] Cherfan et al reported that the common strabismus subtypes associated with DVD were congenital esotropia (53%), esotropia with a developmental deficit (25%), and accommodative esotropia (3.4%) in declining order.[18]

Kutluk et al reported a DVD prevalence of 12.5% in patients with sensory hypertropia.[19] Cherfan et al reported that the common strabismus subtypes associated with DVD were congenital esotropia (53%), esotropia with a developmental deficit (25%), and accommodative esotropia (3.4%) in declining order.[18] Dissociated vertical deviation (DVD) is an uncommon but clinically significant form of strabismus, typically manifesting in early childhood; this is strongly associated with infantile esotropia and other early-onset strabismic syndromes.

Frequency and Prevalence

• United States and Europe: DVD is reported in 50% to 90% of patients with infantile esotropia and in 60% to 80% of those with a history of infantile strabismus surgery. In the general population, the estimated prevalence is 1% to 1%, though precise figures are limited due to underdiagnosis in mild or latent cases.
• Worldwide: Studies from Asia, the Middle East, and South America suggest similar associations, though prevalence data vary widely, reflecting differences in study methodology and access to pediatric ophthalmology services. DVD is frequently reported in tertiary care centers as part of complex strabismus cases rather than in community-based surveys.
• Sex distribution: Most study results show no significant sex predilection. Male and female patients are affected equally.
• Age of onset: DVD usually manifests between 2 and 5 years of age, often after strabismus surgery, but can appear as early as infancy. This rarely presents in adolescence or adulthood unless long-standing childhood strabismus is present.
• Laterality: DVD is typically bilateral but asymmetric, with one eye more affected. Isolated unilateral cases are less common.[20]

Clinical Epidemiologic Associations

• Infantile esotropia is present in up to 70% to 80% of children with DVD.
• Latent nystagmus and oblique muscle overaction are commonly coexisting ocular motility disorders.
• Family history: Genetic and familial clustering have been suggested, but epidemiologic evidence remains limited.[21]

DVD is rare in the general population but common among children with infantile esotropia, with peak manifestation in early childhood and no sex predilection. The global frequency is underreported outside tertiary centers, but the condition carries consistent epidemiologic associations with early-onset strabismus syndromes.[22]

Pathophysiology

The exact mechanism underlying DVD remains incompletely understood. Still, several theories have been proposed, centering on abnormal binocular development, disruption of fusion, and aberrant vertical vergence control (see Image. Dissociated Vertical Deviation, Pathophysiology). A widely accepted belief is that DVD represents a disorder of binocular sensory processing that manifests as a motor imbalance. The exact cause of dissociated vertical deviation is not well understood. However, a few of the important theories explaining the underlying mechanism include:

• The Bielschowsky theory: Proposed alternating and intermittent excitation of subcortical vertical divergence centers as the cause of DVD.
• Later, it was thought of as a dorsal light reflex that modulates the central vestibular tone. Any fluctuations in the binocular visual input were supposed to stimulate the visual-vestibular reflex.[23] 
• Guyton described it as a nystagmus blocking mechanism.[24]
• Spielmann suggested an imbalance of binocular stimulation.
• Few authors have also postulated an imbalance between the cortical input and subcortical pathways as the underlying pathology.[4][25]

Abnormal Binocular Development

• DVD is strongly associated with early-onset strabismus (especially infantile esotropia), suggesting that abnormal visual experience in the critical period disrupts the development of normal fusion.
• The absence of stable binocular input leads to dysfunction of the supranuclear fusion control centers, resulting in uncontrolled upward drifting of one eye when it is not fixating.[26]

Dissociated Nature of the Deviation

• Unlike comitant hypertropias, DVD is “dissociated,” meaning the deviation is not yoked to the Hering law of equal innervation.
• Each eye can drift upward independently, without a corresponding downward movement of the fellow eye. This reflects an abnormality in supranuclear ocular motor pathways controlling vertical vergence.[27]

Role of Fusion Maldevelopment Nystagmus Syndrome

• DVD often coexists with latent/manifest latent nystagmus and oblique overaction, leading some authors to consider it part of the “fusion maldevelopment nystagmus syndrome.”
• In this model, abnormal binocular control circuits in the brainstem and cerebellum development produce nystagmus and DVD.[16]

Neural Mechanisms

• Brainstem: Dysfunction within the interstitial nucleus of Cajal and posterior commissure is implicated in abnormal vertical vergence signals.
• Cerebellum: Aberrant output from the vestibulocerebellum (flocculus and nodulus) is believed to modulate the dissociated vertical drift.
• Cortical input: Deficient cortical binocular processing contributes to the loss of fusion and failure to suppress abnormal vergence signals.[28]

Clinical Correlates

• DVD is more prominent under inattention, fatigue, or monocular occlusion, consistent with its basis in disrupted fusional control.
• The association with early esotropia, latent nystagmus, and oblique dysfunction further supports the idea of a shared sensory-motor pathway disruption in infancy.

DVD arises from abnormal binocular sensory development in early childhood, leading to a supranuclear disorder of vertical vergence control. Brainstem and cerebellar dysfunction and loss of fusion cause one eye to drift upward independently when not fixating; this is best understood as part of the broader fusion maldevelopment spectrum rather than a simple motor imbalance.[29]

Histopathology

DVD is primarily a functional supranuclear disorder rather than a structural lesion. Unlike diseases with clear histopathologic tissue changes, DVD reflects abnormal neurophysiological control of ocular alignment due to defective development of binocular vision pathways in infancy (see Image. Dissociated Vertical Deviation (DVD), History and Physical Findings). However, correlates from neuropathology, animal models, and associated ocular changes help explain its basis.[4]

• Cortical and subcortical levels
  • Visual Cortex: Abnormal development of binocular neurons in striate and extrastriate cortex, due to early disruption of fusion (commonly from infantile esotropia).
  • Loss of normal cortical suppression mechanisms leads to unbalanced input into ocular motor nuclei.[4]
• Brainstem findings
  • Dysfunction has been localized to the interstitial nucleus of Cajal and posterior commissure, which mediate vertical gaze and vergence.
  • Abnormal output causes asymmetric innervation of vertical recti and oblique muscles, independent of the Hering law.[30]
• Cerebellar involvement
  • Vestibulocerebellum (flocculus, nodulus) is implicated in adaptive control of eye movements.
  • Histopathologic/functional studies suggest disinhibition of vertical vergence pathways, resulting in dissociated hypertropia.
  • Cerebellar lesions in experimental primates can reproduce DVD-like phenomena.[27]
• Ocular and muscular correlates
  • Extraocular muscles themselves show no primary histopathological abnormality in DVD.
  • Secondary changes such as fibrosis or hypertrophy may be seen following long-standing strabismus or surgery, but these are nonspecific.[30]
• Neurophysiologic correlates
  • Rather than true histopathology, DVD reflects a fusion maldevelopment nystagmus syndrome.
  • Persistent abnormal neuronal firing in ocular motor integrators (brainstem + cerebellum) results in dissociated vertical drifts.[31]

Histopathology of DVD does not reveal local tissue damage but points to neurodevelopmental dysfunction within the visual cortex, brainstem vertical gaze centers, and cerebellar control circuits. The disorder arises from abnormal binocular development in infancy, leading to supranuclear dysregulation of vertical vergence pathways. No intrinsic disease of the extraocular muscles is found, making DVD a functional, centrally mediated condition rather than a peripheral structural pathology.[32]

Toxicokinetics

DVD is a neurodevelopmental strabismic disorder and not a toxin-mediated disease. Therefore, toxicokinetics in the classical sense (absorption, distribution, metabolism, excretion of toxins) does not apply directly to the pathogenesis. However, the concept becomes relevant when considering pharmacotherapy for the management of associated ocular motility or amblyopia-related complications, especially in children who may require prolonged therapy.[7]

Anticholinesterase Agents

• Refractory DVD/strabismus: Agents like echothiophate iodide were rarely historically used to induce miosis and augment accommodative effort.
• Absorption/metabolism: Topical absorption with systemic distribution; hydrolyzed by plasma cholinesterases
• Toxicity: Can cause iris cysts, prolonged paralysis with succinylcholine, and systemic cholinergic effects
• Clinical Relevance: Largely obsolete due to systemic adverse effects [3]

Botulinum Toxin, Botox

• Botox: Sometimes used in the nonsurgical management of DVD by injection into the superior rectus
• Absorption/distribution: Acts locally at the neuromuscular junction; blocks acetylcholine release with minimal systemic absorption
• Metabolism/Excretion: Degraded locally by proteolysis
• Toxicity: Local ptosis, overcorrection, and rare systemic weakness
• Kinetics: Onset within days, peak effect at 1 to 2 weeks, resolution in 3 to 4 months [12]

Corticosteroids (Adjunctive in Inflammatory Strabismus)

• Not a primary treatment for DVD; may be used when ocular inflammation coexists
• Absorption: Topical or systemic
• Metabolism: Hepatic
• Excretion: Renal
• Toxicity: Glaucoma, cataract, systemic effects with prolonged use  [33]

Clinical Implications

• DVD is usually managed surgically (eg, superior rectus recession, inferior oblique weakening), but pharmacologic adjuncts require careful dosing and monitoring in children.
• Understanding the toxicokinetics of agents such as batrachotoxin and rare cholinesterase inhibitors is critical to balance efficacy with safety.

While DVD has no direct toxicokinetic basis, drugs occasionally used in its management (echothiophate iodide, botulinum toxin, corticosteroids) require awareness of their absorption, metabolism, and adverse effect profiles. The relevance of toxicokinetics in DVD lies in the safe use of adjunctive pharmacologic therapies, especially in pediatric and strabismus populations.[33]

History and Physical

Dissociated vertical deviation rarely presents in infancy, but is usually seen in patients between 2 and 5 years old. This condition can present as an isolated finding or be associated with other forms of strabismus, such as infantile esotropia, most commonly, or rarely, infantile exotropia, or Duane retraction syndrome.[34] This is usually bilateral and asymmetrical. The deviation is often more prominent in the amblyopic eye. The clinical features can be broadly divided into:

Deviation: This is defined as the upward drifting of the nonfixating eye when the patient fixates on the target with the other eye. This vertical deviation is often associated with extortion and slight abduction movement of the deviated eye. No movement is seen in the contralateral eye, as the uncovered eye takes up fixation. Thus, DVD is said to disobey the Herring law of ocular motility.

• Head posture: An abnormal head posture can be associated with one-third of the patients with DVDs. This is a motor adaptation to maintain binocular single vision. Patients presenting with this adaptation do not complain of double vision and tend to have good vision in both eyes.
• Sensory adaptations: Patients have binocular vision in the normal state, but fusion is lost when one eye deviates. The image from the deviated eye is suppressed, thus eliminating diplopia.[7]

Types of DVD

• Comitant: The vertical deviation is the same in abduction, primary position, and adduction. 
• Incomitant: There is a significant difference in the deviation in abduction, primary position, and adduction.[22] 

Types Based on Degrees of Deviation

This is defined based on the degrees of deviation measured in prism diopters (PD).

1. Mild (0 to 9 PD)
2. Moderate (10 to 19 PD)
3. Severe (>20PD) [35]

History

Age of onset

• Most cases become evident between 2 and 5 years of age, coinciding with the development of visual attention and parental recognition of abnormal ocular movements.
• Rarely, a subtle DVD may be detectable in infancy but becomes clinically significant only after strabismus surgery (especially infantile esotropia surgery).[33]

Parental/patient observations

• Parents often describe the eye as "wandering upward" when the child is daydreaming, fatigued, or inattentive.
• DVD is intermittent, and parents may notice it more in photographs where one eye appears higher.
• Older children and adults may report awareness of eye drift in mirrors or may be teased about a cosmetic misalignment.[36]

Symptoms

• Diplopia is rare because the brain typically suppresses the deviating eye.
• Blurred vision is possible if the DVD is large and intermittent.
• Asthenopia: Some patients may report eye strain during near tasks due to intermittent ocular misalignment.
• Cosmesis is the most frequent complaint in adolescents and adults.[37]

Associated History

• This condition often coexists with infantile esotropia (present in 60%–80% of cases).
• This also may be associated with latent or manifest latent nystagmus.
• A history of strabismus surgery is common, with DVD often becoming more obvious postoperatively.
• A family history of strabismus, amblyopia, or nystagmus may be elicited.[32]

Physical Examination

General features

• Laterality: Typically bilateral but asymmetric; one eye may consistently demonstrate a larger deviation (see Image. Bilateral Exotropia)
• Character: A slow, spontaneous upward drift of the nonfixating eye, usually accompanied by excyclotorsion and abduction [36]

Cover-uncover test

• Hallmark finding: When one eye is covered, the nonfixing eye drifts upward; when uncovered, it slowly drifts back down without a corresponding downward movement of the other eye (violating the Hering law).
• The deviation may be more pronounced in distant fixation, inattention, or fatigue.[38]

Quantification

• Magnitude usually ranges from 8 to 15 prism diopters, but can be >20 PD in severe cases.
• The amplitude is often variable, even within the same patient at different examination times.[39]

Ocular motility

• Frequently associated with inferior oblique overaction
• May coexist with V-pattern strabismus
• No significant restriction of elevation or depression in versions, distinguishing DVD from restrictive or paretic causes [40]

Binocular sensory status

• Fusion: Poor or absent; fusional amplitudes are small
• Stereopsis: Usually reduced or absent (common in early-onset strabismus)
• Suppression: Deviating eye is typically suppressed during upward drift, preventing diplopia [41]

Associated ocular signs

• Latent or manifest latent nystagmus: Often present, especially in esotropic patients.
• Amblyopia: Frequently coexists in one eye due to strabismic amblyopia, requiring careful visual acuity assessment.
• Photophobia: Rare but reported in cases with large-amplitude DVD.[42]

Systemic/neurological exam

• No systemic abnormalities; DVD is an isolated ocular motility disorder
• Neurological exam is normal unless there is an associated secondary cause (rare)[43]

DVD typically presents in early childhood, most often in children with infantile esotropia or a history of strabismus surgery (see Table 3). Parents report an intermittent upward drift, often bilateral and asymmetric, worse with fatigue or inattention. On exam, the hallmark finding is a slow upward drift of the nonfixating eye with excyclotorsion, not following the Hering law (see Image. Evaluation Pattern of  Dissociated Vertical Deviation). This is usually associated with latent nystagmus, inferior oblique overaction, reduced fusion, and poor stereopsis, but systemic and neurological findings are normal.[44]

Table 3. History and Physical Examination in Dissociated Vertical Deviation

Evaluation

The diagnosis of dissociated vertical deviation is based on clinical examination alone. A few of the important tests include:

• Cover/uncover test: Spielmann translucent occluder is used.
  • Manifest DVD: Once the fixating eye is covered, the deviated eye shows a downward movement to take up the fixation
  • Latent DVD: The deviation manifests only once the eyes are dissociated. In this, no movement of the uncovered eye occurs; the eye is elevated and moves down once it is uncovered.[45]
• Head tilt test: The deviation of the eye increases on contralateral head tilt.[46]
• Bielschowsky graded density filter test: In this test, when one eye is covered, it elevates under the cover, and the other eye takes up the fixation. The filter bar, consisting of an increasing density of neutral density filters, is placed before the fixing eye. As the filter of gradually greater density is placed before the fixing eye, the elevated eye starts moving down. When the filters of lesser density are placed in front of the fixing eye, the other eye undercover will start elevating again.[47]
• Red filter test: This is also a dissociation test. Torchlight is shown as a target, and red glass is placed in front of one eye. The red glass dissociated the eyes. The eye behind the filter drifts up, and the patient localizes the red image of the fixation light. In the DVD, the red light is always seen below the fixation light, regardless of which eye the filter is placed in. This helps differentiate DVD from other cyclo-vertical deviations, in which red light position changes relative to the fixation light based on which eye fixates.[48]
• Measurement of DVD: This is done using a base-down prism. A prism is placed in front of the deviated eye first, and the patient is asked to fixate on a target located at a distance of 6 meters. The occluder is then shifted to the fixating eye, allowing the deviating eye to take up fixation. The alternate cover test is repeated with prisms of greater power until no downward movement of the deviated eye is noted. This test must be repeated for each eye in patients with bilateral DVDs.[49]

Grading of DVD

• 1+ deviation= a slight deviation
• 2+ deviation= a small deviation
• 3+ deviation= a moderate deviation
• 4+ deviation= a large deviation [50]

A DVD is primarily a clinical diagnosis, established through history and a detailed orthoptic/ocular motility examination. Investigations are directed toward quantifying the deviation, ruling out differential diagnoses, and planning management.

Clinical Examination

• History Taking:
  • Age of onset, frequency, triggers (fatigue, inattention, occlusion)
  • Previous strabismus surgery or history of infantile esotropia
  • Family history of strabismus or amblyopia
• Visual acuity testing:
  • To assess for amblyopia in one or both eyes, which is common in strabismic children
• Cover tests (mandatory):
  • Cover-uncover test: Reveals slow, spontaneous upward drift of the covered (nonfixating) eye with excyclotorsion, a hallmark of DVD
  • Alternate cover test: Helps quantify the deviation using the prism cover measurement
• Laterality assessment:
  • Determine whether the DVD is bilateral but asymmetric or unilateral
• Measurement of deviation:
  • Use prism diopters at distance and near fixation
  • Note variability in amplitude depending on attention, fatigue, or fixation target
• Ocular motility evaluation:
  • Assess for inferior oblique overaction or V-pattern strabismus.
  • Check for coexistence of latent/manifest latent nystagmus.
• Binocular sensory testing:
  • Worth 4-dot test and Bagolini striated lenses are used to evaluate fusion
  • Stereopsis testing (Titmus Fly, Randot)–usually reduced or absent [51]

Ancillary Tests

• Cycloplegic refraction:
  • Rule out associated refractive errors (hyperopia, astigmatism)
  • Prescribe spectacles for amblyopia management
• Fundus examination:
  • Evaluate for torsion (excyclotorsion often noted in DVD)
  • Exclude structural anomalies
• Ocular imaging (optional):
  • Not required for diagnosis, but optical coherence tomography may be used if coexisting amblyopia or structural causes are suspected [52]

Guidelines Perspective

• American Association for Pediatric Ophthalmology and Strabismus, AAPOS:Clinical evaluation with the prism cover test is recommended as the gold standard. Surgery is indicated only if the deviation is cosmetically significant or interferes with binocular function.
• American Academy of Ophthalmology, AAO:This organization emphasizes comprehensive strabismus workup, including ocular motility, binocular function, and refraction, with surgery tailored to functional/cosmetic needs.
• International Practice (UK, Europe, Asia):The guidelines are similar, stressing careful differentiation from true hypertropia, oblique dysfunction, and skew deviation.[53]

DVD evaluation relies on a detailed clinical assessment, especially covering testing and prism measurement, supported by binocular sensory testing and refraction. No specialized laboratory or radiographic test is required. International guidelines emphasize accurate diagnosis, quantification, and differentiation from other vertical strabismus for appropriate surgical planning.[49]

Treatment / Management

Treatment of dissociated vertical deviation can vary from observation to nonsurgical or surgical.

• Observation: This might be sufficient in patients with latent DVD, especially those older than 8, when the risk of amblyopia is not of concern, with small degrees of anomalous head postures, and not a significant cosmetic blemish.
• Nonsurgical: Conservative therapy, in the form of changing the fixation pattern or encouraging fusion, can be useful for small deviations. A slight optical blur induced in the fixating eye example by adding a +2D lens shifts the fixation preference to the other eye, and thus, DVD is avoided.[54] Injection of Botulinum toxin into the superior rectus has also been described.[55]
• Surgical: This is indicated when there is greater than +2 deviation; large DVD frequently manifests, anomalous head posture, or a significant cosmetic blemish. The literature describes several surgical options for DVD.

Important surgical options among these include:

• Inferior oblique weakening [56]
• Anteriorization of the inferior oblique [57] 
• Anteriorization of the inferior oblique with resection [58] 
• Superior rectus large recession (7 to 10 mm) [59][60]
• Faden operation with superior rectus recession of 3 to 5 mm [61] 
• Inferior rectus resection: 4 mm for small deviations, 6 mm for intermediate deviations, and 8mm for large deviations [62] 
• Anteronasal transposition of the inferior oblique [63]
• Inferior rectus tucking [64]
• Four-muscle oblique surgery [50][65]
(A1)

The surgical treatment can be planned based on the DVD grade and the presence or absence of inferior oblique (IO) overaction.

• DVD with no IO overaction: Superior rectus recession + inferior rectus resection
• Moderate DVD with IO overaction: Recession with anteropositioning of IO
• Severe DVD with IO overaction: Recession with anteropositioning of IO + superior rectus recession (7 to 10 mm) [66]

The severity of deviation, cosmetic significance, functional impact, and association with other strabismic disorders guide DVD management. Most children are asymptomatic, and treatment is indicated primarily for cosmetic concerns, large-angle deviation, or when DVD interferes with fusion.

Observation and Nonsurgical Management

• Observation:
• A small, intermittent, and cosmetically insignificant DVD requires no active intervention.
• Parents should be reassured about the benign course.[50]
• Amblyopia therapy:
• If amblyopia coexists, treatment with occlusion therapy or optical correction is essential.
• Prisms/glasses:
• This is rarely useful for DVD correction, but may help address associated horizontal deviation or refractive error.[67]
(A1)

Surgical Management (Mainstay of Treatment)

Surgery is considered when the DVD is large (>8–10 prism diopters), cosmetically disfiguring, or interferes with binocular vision.[66]

Superior rectus recession

• This is the most common surgery for DVD.
• Bilateral superior rectus recession is often performed in bilateral DVD.
• The amount of recession is titrated to the deviation magnitude.[68]

Inferior oblique weakening

• This is indicated when the DVD is associated with IO overaction.
• Procedures: IO recession, myectomy, or anterior transposition.
• IO anterior transposition has the dual benefit of reducing IO overaction and DVD.[69]

Combined procedures

• In large or asymmetric DVDs with IO overaction, SR recession + IO weakening may be combined.
• Unilateral DVD: This includes unilateral SR recession, occasionally combined with IO anterior transposition.

Posterior fixation sutures (Faden procedure)

• This is applied to the superior rectus in selected cases, especially when DVD is incomitant.[70]

Role of botulinum toxin

• Rarely used as a temporary measure for DVDp (particularly when surgery is contraindicated)
• Provides transient reduction but is not a definitive treatment

Prognosis after surgery

• Surgical success rates: A 60%–80% reduction in deviation has been shown.
• Residual DVD is common but usually less cosmetically significant.
• Repeat surgery may be needed in severe or recurrent cases.[71]

Guideline-based approach

• AAPOS/AAO Recommendations:
• Surgery is indicated only if the DVD is large, cosmetically unacceptable, or interferes with fusion.
• The choice of procedure depends on the presence/absence of IO overaction.
• The emphasis is on tailoring surgery to asymmetry (bilateral vs unilateral).

DVD is usually observed if mild, but for larger, cosmetically significant deviations, superior rectus recession with or without inferior oblique weakening is the treatment of choice. Combined procedures are often required in asymmetric or severe cases. Prognosis is generally favourable, though recurrence or residual deviation may occur.[66]

Differential Diagnosis

The closest and most important differentials to consider are inferior oblique overaction (IOOA) and acquired skew deviations; this is important to differentiate, as the surgical approach differs for these conditions.

The important differentiating points between IOOA and DVD include:

• Hyperdeviation is greatest in adduction in cases of IOOA. In contrast, in DVD, the hyperdeviation remains similar in primary, adducted, and abducted gaze positions.
• The V pattern is associated with IOOA but is absent in the DVD.
• Superior oblique under action is usually associated with IOOA.
• An extorted macula can be seen in IOOA, but it is absent in DVD patients.
• The Bielschowsky phenomenon is present in DVD, while it is absent in true hypertropia.[72]

The important differentiating points between acquired skew deviation and DVD (see Table 4) include:

• Skew deviations can present at any age, but the most common age of presentation among those with DVDs is around 2-4 years. 
• In skew deviations, there is intortion of the higher eye and extortion of the lower eye, while vice versa in DVD.
• A brainstem or cerebellar region lesion can be associated with skew deviation.
• Vertical diplopia is associated with skew deviation, while DVD is not associated with similar complaints.
• Seesaw or hemi-seesaw nystagmus is associated with skew deviation, while DVD is associated with latent nystagmus.[73]

Table 4. Differential Diagnosis of DVD

DVD should be distinguished from superior oblique palsy, inferior oblique overaction, skew deviation, comitant hypertropia, monocular elevation deficiency, latent nystagmus, and ocular tilt reaction. Careful evaluation of gaze dependency, torsional changes, compliance with the Hering law, and associated neurologic/systemic findings helps establish the correct diagnosis.[74]

Pertinent Studies and Ongoing Trials

Pertinent studies and ongoing trials include the following:

• Most evidence for DVD management comes from retrospective case series and small prospective cohorts; randomized trials are rare.
• Common surgical options include bilateral superior rectus (SR) recession (± posterior fixation), IO anteriorization/anterior-nasal transposition, and combined SR + IO procedures for mixed DVD/IO overaction.
• Across series, surgery typically reduces DVD by ~60% to 80% and improves head posture/manifestation of dissociation; undercorrection and asymmetry remain the main limitations.
• Risk of iatrogenic hypotropia and anti-elevation syndrome is higher with aggressive SR weakening or IO anteriorization—careful titration and symmetry are key.
• Nonsurgical measures (occlusion, optical penalization, amblyopia therapy) help in mild or intermittent DVD, especially in children (see Table 5).[74]

Table 5. Representative DVD Studies 

DVD, dissociated vertical deviation; IO, inferior oblique; IOOA, inferior oblique overaction; SR, superior rectus

Evidence Gaps

Standardized dose–response tables, long-term (>5 years) outcomes, and validated patient-reported measures (cosmesis, asthenopia).

Ongoing/Needed Trials

• Prospective multicenter registry tracking pre-/postoperative angle, incomitance, stereopsis, and patient-reported outcome measures.
• Randomized/controlled trials comparing SR recession vs IO anteriorization in DVD with IO overaction, and evaluating posterior fixation augmentation.
• Technique refinements (graded anterior-nasal transposition vs classic IO anteriorization) to minimize anti-elevation.
• Nonsurgical protocols (standardized amblyopia/penalization pathways) for intermittent or small-angle DVD.[75]

Treatment Planning

Initial Assessment

• Severity of deviation: Angle of DVD (mild <10 PD, moderate 10–15 PD, severe >15 PD)
• Laterality: Bilateral (most common) vs unilateral or asymmetric presentation
• Associated anomalies: IOOA, latent nystagmus, amblyopia, or dissociated horizontal deviation
• Functional impact: Cosmesis, abnormal head posture, asthenopia, or suppression
• Age and visual potential: Younger children may require amblyopia management first [4]

Nonsurgical Management

• Observation: Mild, intermittent, or cosmetically insignificant cases can be monitored
• Amblyopia therapy: Occlusion or penalization to equalize fixation preference
• Prisms: Limited role due to dissociated nature (not comitant)
• Orthoptic therapy: Minimal efficacy, but may help in binocular stabilization [76]

Indications for Surgery

• Large DVD (>12–15 PD) affecting cosmesis
• Asymmetrical DVD with marked cosmetic disfigurement
• Frequent manifest DVD interfering with binocularity
• Associated IO overaction producing V-pattern or overelevation in adduction [77]

Surgical Options

DVD, dissociated vertical deviation; IO, inferior oblique; IOOA, inferior oblique overaction; SR, superior rectus

Postoperative Care and Follow-Up

• Follow up regularly for residual/recurrent DVD.
• Monitor for iatrogenic hypotropia, anti-elevation syndrome, or induced vertical incomitance.
• Continue amblyopia management if needed.
• Counsel parents regarding variable outcomes and the possibility of staged surgery.[78]

Treatment Strategy

• Mild/asymptomatic DVD: Observation + amblyopia therapy
• Moderate DVD or asymmetry: Targeted SR or IO procedure
• Severe/bilateral DVD (>15–20 PD): Bilateral SR recessions (± posterior fixation)
• DVD with IO overaction: IO anteriorization or anterior-nasal transposition ± SR surgery
• Residual/recurrent cases: Secondary procedures or combined surgery [21]

Treatment must be individualized based on severity, symmetry, cosmesis, presence of IOOA, and binocular potential. Surgery aims at reducing the manifest deviation to a cosmetically and functionally acceptable level rather than complete elimination.

Toxicity and Adverse Effect Management

Adverse effects and surgical complications can occur with DVD. See Table 6 below for more information.

Table 6. Surgical Complications and Their Management

Nonsurgical Risks

• Amblyopia progression: Persistent suppression in the deviating eye; managed with occlusion or penalization therapy.
• Cosmetic dissatisfaction: Parents/patients may perceive residual updrift postop; preoperative counseling is required to set realistic expectations.
• Loss of fusion potential: Rare, but can occur in late or incomplete correction cases.[79]

Preventive Strategies

• Graded and symmetric surgical dosages to minimize overcorrection/undercorrection
• Tailoring surgery to the associated IO overaction (SR vs IO approach)
• Preoperative counseling regarding the possibility of recurrence or staged procedures
• Regular follow-up for early detection of complications [7]

DVD management is aimed at functional improvement and cosmesis, not complete elimination of deviation. Complications like hypotropia, anti-elevation, and residual asymmetry are best prevented with careful planning, conservative dosages, and stepwise surgical approaches. When they occur, most can be managed with observation, prism therapy, or revision surgery.[66]

Staging

The following details the DVD staging; please see Table 6 below for a complete summary.

Based on the Magnitude of Deviation

• Mild DVD: <10 PD; often intermittent, cosmetically insignificant, rarely requires surgery
• Moderate DVD: 10–15 PD; frequently noticeable, may cause cosmetic concern, surgical consideration if persistent
• Severe DVD: >15–20 PD; manifests most of the time, cosmetically disfiguring, usually a surgical candidate [49]

Based on Laterality

• Unilateral DVD: Rare; usually in the amblyopic eye
• Bilateral symmetrical DVD: Common in infantile esotropia; both eyes drift equally
• Bilateral asymmetrical DVD: One eye shows greater elevation than the other, often requiring an asymmetric surgical approach [80]

Based on the Frequency of Manifestation

• Latent DVD: Manifests only on dissociation (cover test)
• Intermittent DVD: Appears when fatigued, daydreaming, or under stress
• Manifest DVD: Constantly present; cosmetically significant [81]

Based on Associated Findings

• DVD with IOOA: Requires a combined approach (IO anteriorization)
• DVD without IOOA: Best managed with SR weakening procedures
• DVD with amblyopia/latent nystagmus: Indicates broader sensory disruption and may impact management [82]

Table 6. Practical Staging of DVD Summary

DVD is not formally staged in the way cancers or systemic diseases are, but clinicians commonly describe it in terms of severity, laterality, frequency, and associated anomalies. This practical staging helps guide treatment planning (eg, observation vs surgery and unilateral vs bilateral procedures).[22]

Prognosis

Depending on the frequency or degrees of deviation, the dissociated vertical deviation can be observed, or nonsurgical or surgical treatment might be needed. No major studies have compared nonsurgical versus surgical management options. The most frequently performed procedures include inferior oblique anteriorization or superior rectus weakening. The choice of surgical procedure depends on the degree of deviation, the degree of anomalous head posture, and the surgeon's preference.[72]

Natural History

Dissociated Vertical Deviation is generally non-progressive and persists throughout life once it develops. It often becomes apparent in early childhood, especially in those with infantile esotropia, amblyopia, or latent nystagmus. In many cases, the deviation may appear more noticeable with fatigue, inattention, or loss of fixation.[83]

Visual Prognosis

Visual acuity and long-term ocular health are usually unaffected if amblyopia is appropriately managed. However, untreated amblyopia can worsen outcomes, particularly in unilateral or asymmetric cases. Binocular vision potential is limited in most children with DVD, as it reflects early sensory disruption, but some patients may retain fusion in primary gaze.[84]

Cosmetic and Functional Outcomes

Mild DVD may be tolerated well, with minimal cosmetic impact. Moderate to severe cases can cause significant cosmetic disfigurement due to frequent upward drifting of one eye, which is often the main reason for surgical intervention.[50]

Surgical prognosis

Surgery (superior rectus recession, inferior oblique anteriorization, or combined procedures) typically reduces DVD magnitude by 60% to 80%. However:

• Residual DVD is common, and complete elimination is rare.
• Recurrence can occur, particularly in young children and asymmetric cases.
• Complications such as hypotropia or anti-elevation syndrome may affect long-term outcomes if surgical dosing is excessive.[85]

Quality of life

With appropriate treatment, most patients achieve cosmetically acceptable alignment and functional improvement. Residual DVD is often small enough to be socially inconspicuous. Early diagnosis and amblyopia management improve visual outcomes and reduce psychosocial impact. DVD has a benign visual prognosis but a variable cosmetic prognosis. Most patients achieve satisfactory long-term outcomes with observation or surgery, but recurrence and incomplete correction are common, requiring realistic expectations and, occasionally, staged procedures.[86]

Complications

The complications can be divided into those related to the disease, anesthesia, or those related to the surgical process (intraoperative or postoperative)

• Related to disease: Amblyopia, torticollis, and contracture of the sternocleidomastoid muscle.
• Anesthesia-related: Oculocardiac reflex, malignant hyperthermia, cardiac arrest, hepatic porphyria, or succinylcholine–induced apnoea
• Surgical complications:
  • Intraoperative: Hemorrhage, Lost or slipped muscle, eyeball perforation, inadvertent injury to surrounding structures/muscles, operation of the wrong muscle or eye
  • Postoperative complications include suture reaction, conjunctival granuloma, anterior segment ischemia, diplopia, retinal detachment, under- or overcorrections, and adhesive syndrome.[87]

Although the DVD is not vision-threatening, complications arise mainly from its clinical course, associated conditions, and surgical management (see Table 7). 

Natural/Functional Complications

• Amblyopia: Common in unilateral or markedly asymmetric cases due to suppression of the deviating eye
• Loss of Binocular Function: Poor fusion and stereopsis (result from early binocular disruption)
• Cosmetic Impact: Visible updrift of one eye causes social/psychological distress
• Abnormal Head Posture: Rare, but may be adopted to minimize the cosmetic impact or maintain fusion [88]

Table 7. Surgical Complications of DVD

Psychosocial/Quality-of-Life Complications

• Cosmetic disfigurement: Persistent visible updrift can impact confidence and social interactions even after surgery.
• Parental anxiety: In pediatrics, visible eye movements often cause parental concern, requiring counseling.[89]

DVD complications are most often cosmetic and functional rather than vision-threatening. Long-term outcomes are generally good with careful amblyopia management, surgical planning, and parental counseling. The main risks relate to residual asymmetry, hypotropia, or anti-elevation syndrome after surgery.[84]