Internal ophthalmoplegia--a complication of ocular varicella

Isolated Internal Ophthalmoplegia Secondary to Herpes Zoster Ophthalmicus: A Rare Case Report

Herpes zoster becomes latent in the sensory ganglia after the primary infection and may reactivate many years later to produce shingles in adults. Involvement of the ophthalmic branch of the trigeminal nerve with this virus is called Herpes zoster ophthalmicus (HZO). The eyelid skin, cornea, uvea, retina, optic nerve and other cranial nerves can be affected by HZO. Isolated internal ophthalmoplegia can rarely be seen. Clinicians should be aware of this condition and HZO must be kept in mind in the differential diagnosis of anisocoria.

A case of internal ophthalmoplegia associated with varicella zoster

The authors report a case of internal ophthalmoplegia in a 5-year-old boy presenting after primary varicella infection. This is an uncommon and mostly irreversible ocular manifestation after chickenpox. The internal ophthalmoplegia showed a potential mild improvement with oral acyclovir. Consideration should be given to starting treatment on presentation in such cases.

Disorders of the pupil

Pupil size is determined by the interaction of the parasympathetic and the sympathetic nervous system. The parasympathetic system conducts the light reaction with its major center in the dorsal midbrain. The sympathetic nervous system acts either directly on the dilator muscle (peripherally) or centrally by inhibiting the Edinger-Westphal nucleus. Psychosensory reactions are transmitted via the sympathetic system. The afferent input of the light reflex system in humans is characteristically wired, allowing a detailed analysis of a lesion of the afferent input. Even in humans a subgroup of ganglion cells containing melansopsin plays an important role as a light sensor for the pupillary system. To diagnose normal pupillary function, pupils need to be isocoric and react bilaterally equally to light. Anisocoria indicates a problem of the efferent pupillary pathway. Pupillary disorders may involve the afferent pathways (relative afferent pupillary defect) or the efferent pathways. Physiological anisocoria is a harmless condition that has to be distinguished from Horner's syndrome. In this case pharmacological testing with cocaine eye-drops is helpful. Disorders of the parasympathetic system will impair the light response. They include dorsal midbrain syndrome, third-nerve palsy, and tonic pupil. Tonic pupils are mainly idiopathic and do not need imaging. Disorders of the iris, including application of cholinergic agents, need also to be considered in impaired pupillary light reaction.

Delayed internal ophthalmoplegia and amblyopia following chickenpox

INTRODUCTION

Chickenpox can be responsible for various ophthalmologic complications [4].

DISCUSSION

An internal ophthalmoplegia could be observed in this context and is responsible for a fixed pupil [2]. This complication is extremely rare and seems to occur mainly in young children during the two weeks following cutaneous eruption. We report an atypical observation of internal ophthalmoplegia due to chickenpox that occurs with a particularly prolonged interval.

CONCLUSION

We would like to emphasize the consequences of the paralysis of accommodation associated with this tonic pupil on visual acuity.