Spasm of the Near Reflex

Key Points at a Glance

1. Spasm of the Near Synkinetic Reflex

Spasm of the near synkinetic reflex is a condition characterized by the triad of accommodation spasm, acute convergent strabismus, and miosis.

It is also called spasms of the near reflex or convergence spasm. It is a paroxysmal, sustained adduction of both eyes, where the three components of the near response (convergence, accommodation, and miosis) occur simultaneously as a supranuclear, binocular, conjugate movement. These cannot be voluntarily separated.

This condition is broadly divided into functional and organic types. ¹⁾

Functional (psychogenic): Most common. Anxiety and psychological distress are the main triggers. It is classified as a conversion disorder.
Organic: Head trauma, multiple sclerosis³⁾, metabolic encephalopathy, Arnold-Chiari malformation, tumors, etc. It may also result from increased irritability of the convergence center at the midbrain dorsal level or organic lesions (pseudo sixth nerve palsy).

Q Does convergence spasm occur in both children and adults?

This condition is classified under pediatric ophthalmology, but adult-onset cases have also been reported.²⁾ In functional cases, it can occur in healthy individuals, with anxiety and psychological distress as triggers regardless of age.

2. Main symptoms and clinical findings

Subjective symptoms

Blurred vision: Transient blurring of vision.
Diplopia: Homonymous diplopia when looking at distant objects (caused by inward deviation of the eye).
Asthenopia: Eye fatigue or discomfort.
Decreased visual acuity: Decreased vision due to myopia.
Non-ocular symptoms: May be accompanied by nausea, vomiting, headache, and eye pain.

Clinical Findings

Acute esotropia: Paroxysmal, simultaneous, severe esotropia in both eyes persists. Extreme adduction of both eyes is a characteristic finding.
Miosis: Accompanied by simultaneous miosis in both eyes.
Abduction limitation: Observed as variable acute esotropia with abduction limitation.
Convergence angle variability: Characterized by large fluctuations in the convergence angle.
Pseudomyopia: Dry refraction without cycloplegic agents shows apparent myopia with miosis.
Recurrence: Essentially recurrent, worsening during periods of anxiety.
Key point for differentiation: In monocular adduction, the abduction limitation disappears, and miosis also disappears.

3. Causes and Risk Factors

Functional (Psychogenic)

Frequency: The most common cause.

Triggers: Anxiety or emotional distress.

Mechanism: Involves the mechanism of conversion disorder (hysteria).

Characteristics: Often improves when psychological stability is achieved.

Organic

Head trauma: The convergence center is stimulated after trauma, leading to onset.

Multiple sclerosis: Demyelination of the central nervous system affects the convergence center. ³⁾

Metabolic encephalopathy/tumor: Organic lesions at the level of the dorsal midbrain.

Arnold-Chiari malformation: Involvement due to congenital malformation of the posterior cranial fossa.

Q Can stress or anxiety really cause eye symptoms?

In psychogenic near reflex spasm, the mechanism of conversion disorder is thought to cause anxiety and psychological distress to reflexively enhance convergence, accommodation, and miosis. In this case, there are no organic lesions in the eye or nerves, and it often improves with psychological approaches.

4. Diagnosis and Examination Methods

Diagnosis is usually made clinically.

Main Diagnostic Procedures

Cycloplegic refraction: This is an essential test. Hyperopic shift or reduction of existing myopia is observed. The difference from dry refraction can confirm transient accommodative spasm.
Assessment of versions: In binocular versions, abduction limitation is observed, but in monocular versions, the limitation disappears and miosis also disappears. This is a characteristic differential finding of convergence spasm.
Measurement of convergence angle: Confirm that the convergence angle fluctuates significantly.
Imaging: Performed when neurological or systemic findings are present, or when there is a history of closed head injury.
Wavefront sensor: Can simultaneously measure the three components of the near response (accommodation, miosis, convergence) and is considered useful for understanding the pathophysiology.

Differential Diagnosis

It is important to differentiate from the following diseases.

Disease	Key differentiating features
Bilateral abducens nerve palsy	Without miosis or accommodation disorder. Asymmetry present.
Convergence insufficiency (divergence paralysis)	Not accompanied by accommodation disorder or pupillary abnormality.
Myasthenia gravis⁴⁾	Ptosis, easy fatigability. No miosis or accommodative spasm
Multiple sclerosis³⁾	Accompanied by other neurological findings

Convergence spasm is characterized by the triad of high esotropia, miosis, and accommodative spasm. The key to differentiating from abducens nerve palsy is performing the monocular duction test.

Q How is it distinguished from abducens nerve palsy?

Abducens nerve palsy does not involve miosis or accommodation disorders, and the abduction limitation is monocular and does not fluctuate. In convergence spasm, the abduction limitation disappears when performing monocular adduction movement, and miosis also disappears. Additionally, a characteristic feature is that the convergence angle fluctuates significantly. For details, refer to the “Diagnosis and Examination Methods” section.

5. Standard Treatment

Organic Cases

Treatment of the underlying disease is prioritized.

Psychogenic (Functional) Cases

Psychological support: The basic approach is to alleviate the patient’s anxiety and provide a sense of psychological security.
Monocular occlusion: May be effective in eliminating convergence spasm.
Instillation of cycloplegic agents: Performed when convergence spasm persists (e.g., atropine).
Plus lenses (convex lenses): Used to reduce accommodative load. Bifocals may be selected.
Spontaneous resolution: Most cases resolve spontaneously.

Q Will it heal naturally without treatment?

In psychogenic cases, most cases resolve spontaneously. However, in organic cases, treatment of the underlying disease is necessary, and if left untreated, improvement may not occur. If mental stress is a trigger, stress reduction and psychological support are important.

6. Pathophysiology and Detailed Mechanism of Onset

The near reflex is a physiological response in which convergence, accommodation, and miosis occur simultaneously as associated movements when viewing near objects. It is a binocular associated movement under supranuclear control, and each component cannot be voluntarily separated.

Supranuclear fibers to the Edinger-Westphal nucleus (EW nucleus) for the near reflex run ventral to the midbrain pretectal area and posterior commissure, through which afferent fibers of the pupillary light reflex pass. The ratio of neurons involved in the pupillary light reflex and accommodation in the ciliary ganglion is 3:97, with accommodation-related cells overwhelmingly predominant.

The mechanism of convergence spasm varies depending on the cause.

Psychogenic: The mechanism of conversion disorder is involved. Mental distress is thought to cause hyperreflexia of the near response.
Organic: Caused by increased irritability of the convergence center at the dorsal midbrain level or organic lesions (pseudo sixth nerve palsy). Lesions from the dorsal midbrain to the tegmentum, such as tumors, trauma, or demyelination, can be causative.

8. References

Goldstein JH. Spasm of the near reflex: a spectrum of anomalies. Surv Ophthalmol. 1996;40(4):269-278.
Hussaindeen JR. Acute adult onset comitant esotropia associated with accommodative spasm. Optom Vis Sci. 2014;91(4 Suppl 1):S46-51.
Sitole S. Spasm of the near reflex in a patient with multiple sclerosis. Semin Ophthalmol. 2007;22(1):29-31.
Rosenberg ML. Spasm of the near reflex mimicking myasthenia gravis. J Clin Neuroophthalmol. 1986;6(2):106-8.

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