[Spasm of the near reflex. Treatment with botulinum toxin]

The etiology, diagnostics, and treatment of the spasm of the near reflex - a narrative review

Physiological adaptation of the eye to the visual perception of near objects consists of the "near triad": convergence, accommodation, and pupil miosis. Normally, these tend to revert when one stops fixating on a near object. Spasm of the near reflex (SNR) is a pathological phenomenon, which manifests itself by the persistence of the above-mentioned adjustments, which prevents the eye from returning to its relaxed state. In this narrative review, we aim to summarize the etiology, diagnostics, treatment, and prevention of SNR. The literature review was performed by searching online databases. The clinical presentation of SNR is diverse; it presents as isolated accommodative spasm more frequently than impairment of all three components of the near triad. Patients usually present with fluctuations in visual acuity, blurred vision, diplopia, and asthenopia. The etiology is not fully understood. Potential causes include neuroanatomic, organic, and psychogenic disorders. The diagnosis is clinical, based on the constellation of symptoms and assessment of the near triad. The diagnostic golden standard is a cycloplegic examination of refraction, preferably using cyclopentolate hydrochloride (1%, 0.5%, or 0.1% solution). The first-line treatment requires the administration of a cycloplegic drug in combination with plus lenses, flipper lenses, optical fogging, or miotics. For secondary cases, causal treatment should be implemented. Prevention of SNR should be based on eliminating modifiable risk factors. We propose including screening for SNR symptoms in every ophthalmic examination, especially among patients with psychogenic or neural disorders, after brain trauma, or young adults spending much time in front of computer screens.

Periorbital injections of botulinum toxin a: a novel therapeutic option for convergence spasm in neuropsychiatric disorders

PURPOSE

Convergence spasm (CS, spasm of near reflex) is characterized by transient attacks of convergence, miosis and accommodation, often associated with functional neurological disorders. To date, no simple and efficient treatment option is available for CS. This study investigates whether periorbital botulinum toxin injections as used in essential blepharospasm are also a treatment option in these patients.

METHODS

All patients with convergence spasm having been treated with periorbital BoNTA injections in the department of neuro-ophthalmology were identified. Data were extracted from patient files concerning details and subjective effectiveness of botulinum toxin injections and relation to psychiatric or neurological disorders. Patients reporting with a history of closed-head trauma or organic neurologic pathologies possibly causing CS were excluded. A telephone assessment with a standardized questionnaire was performed to evaluate mental health issues as a trigger, as well as the long-term effect and satisfaction with periorbital injections.

RESULTS

Of 16 patients treated with periorbital botulinum toxin injections for convergence spasm, 9 patients reported depression and/or anxiety disorders ongoing or in the past. A median number of 3 injections (range 1-13) was administered with a variable effect (relief of symptoms) between no effect and effect of up to more than 12 weeks. A longitudinal follow-up revealed ongoing symptoms in five patients.

CONCLUSIONS

Periorbital botulinum toxin injections are less invasive than injections in the medial rectus muscle and can be a bridging therapeutic option in patients with CS. Mental health exploration is important due to psychiatric comorbidity.

Unilateral accommodation spasm: Case report and literature review

This case report describes a probable unilateral accommodation spasm in a 10 year-old girl with no significant medical history. The right eye showed decreased visual acuity, 0.2 to 0.6 for far distance and 0.125 for near distance. Refraction without cycloplegia showed myopization up to -6 and cycloplegic refraction of+0.50. The patient had normal ocular motility, orthophoria, normal pupil reflex, normal anterior and posterior segments, normal optical coherence tomography. Neurophysiological tests and brain magnetic resonance imaging were all normal. Treatment with atropine 1% drops for 15 days improved distance visual acuity to 0.8. Accommodation spasm is a rare condition and is usually bilateral. Imaging test are necessary because it may be associated with ocular or head trauma. Treatment consists of cycloplegic drugs (atropine, cyclopentolate); however, there is no defined guideline.

Efficacy of Botulinum Toxin in the Treatment of Convergence Spasm

BACKGROUND

Previous studies have shown that botulinum toxin can be an important adjunct to management of convergence spasm. However, we have not experienced the same level of success in our cohort of patients.

METHODS

Using retrospective review, we collected data on patients presenting to our department with convergence spasm. This included presenting symptoms, examination findings, response to atropine and plus lenses, number and dosage of botulinum toxin injections received, and the status at last follow-up/discharge.

RESULTS

We identified a total of 6 patients with a male: female ratio of 1:1 and mean age of 44.3 years. Commonest symptom was diplopia followed by headache and blurred vision. Depression was present in 4 out of 6 patients. Average pre-injection deviation for near was 32.5 PD ET (Prism Diopters esotropia) and for distance was 27.7 PD ET. All of the patients received botulinum toxin injections to the medial rectus muscle. The response to toxin was variable with an average near deviation at 2 weeks of 10 PD XT (exotropia), range 20 PD XT to 25 PD ET and at 3 months 12.5 PD ET (10 PD XT to 35 PD ET). At the last follow-up, after the toxin effect had worn off, all the patients returned to the pre-injection levels and the symptoms recurred.

CONCLUSION

The response of patients with convergence spasm to botulinum toxin was variable with a recurrence of the deviation once the effect wore off. In our experience, botulinum toxin has a limited role in the management of convergence spasm.

Spasm of the near reflex: A case report

Purpose

Spasm of the near reflex (SNR) is a triad of miosis, excess accommodation and excess convergence. Primary SNR is most often functional in origin We aim to highlight the clinical features which distinguish primary convergence from other conditions with a similar presentation but more sinister underlying aetiology, for example bilateral abducens nerve palsy.

Observations

There is a paucity of published data on SNR, in particular diagnostic criteria and treatment. We report a case of SNR of functional origin in an otherwise healthy young female and discuss the clinical features that differentiate this condition from similar conditions with underlying neurological origin.

Conclusions and importance

SNR is predominantly a clinical diagnosis, and often leads to patients undergoing unnecessary investigations and sometimes treatment. Recognising the salient features that differentiate it could potentially avoid this.