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Year : 2019  |  Volume : 27  |  Issue : 1  |  Page : 44-46

Unilateral Isolated Internal Ophthalmoplegia − Idiopathic Etiology

1 Department of Pediatric Ophthalmology and Strabismus, Sankara Eye Hospital, Bengaluru, Karnataka, India
2 DNB, Dept of Pediatric Ophthalmology and Strabismus, Sankara Eye Hospital, Bengaluru, Karnataka, India

Date of Web Publication4-Jul-2019

Correspondence Address:
Dr. Sowmya Raveendra Murthy
Department of Pediatric Ophthalmology and Strabismus, Sankara Eye Hospital, Varthur main road, Kundlahalli gate, Bengaluru, Karnataka - 560035
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/njo.njo_27_18

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Unilateral internal ophthalmoplegia is rare to occur as an isolated entity. Herein, we report a case of a young boy with isolated unilateral internal ophthalmoplegia, that is, mydriasis with absent near response without external ophthalmoplegia. There was neither light-near dissociation nor supersensitivity to dilute pilocarpine. Neuroimaging including magnetic resonance imaging and magnetic resonance angiography was normal. Follow-up for over 2 years showed no change in pupil size and reaction. The internal ophthalmoplegia was presumed to be idiopathic in nature.

Keywords: III cranial nerve palsy, internal ophthalmoplegia, near reaction, pupil

How to cite this article:
Murthy SR, Sudhakar P. Unilateral Isolated Internal Ophthalmoplegia − Idiopathic Etiology. Niger J Ophthalmol 2019;27:44-6

How to cite this URL:
Murthy SR, Sudhakar P. Unilateral Isolated Internal Ophthalmoplegia − Idiopathic Etiology. Niger J Ophthalmol [serial online] 2019 [cited 2022 Nov 30];27:44-6. Available from:

  Introduction Top

Dilated and fixed pupil need a stepwise evaluation. Presence of light-near dissociation and supersensitivity to dilute pilocarpine points toward Adie’s pupil, wherea absence of the above responses along with constriction to 1% pilocarpine suggest 3rd cranial nerve involvement as etiology. The latter is termed as internal ophthalmoplegia.[1],[2]

Bilateral occurrence of internal ophthalmoplegia as an isolated entity has been shown to be an initial manifestation of Miller Fisher variant of Guillain Barré syndrome. The unilateral occurrence of the same is rare.[3],[4] Unilateral internal ophthalmoplegia may be the initial manifestation of III nerve palsy and needs to evaluated and monitored.[1] Anomalous posterior cerebral artery as a cause of 3rd cranial nerve palsy has been well documented.[5],[6] We hereby describe a case of internal ophthalmoplegia with normal MRI and MRA, hence presumed to be idiopathic.

  Case report Top

A 15-year-old boy presented to us with a history of diminution of near vision in the right eye since 20 days. There was no history of trauma or instillation of drops prior to presentation.

On examination, visual acuity in the right eye was 6/6, N36 and in the left eye was 6/6, N6. Ocular movements were normal. Cover tests were orthophoric for distance. Anisocoria was present with right eye having dilated pupil (6–7 mm) with absent direct or consensual light and near response [[Figure 1]]. Left eye pupil was 3 mm in size with normal response to light and near stimuli.
Figure 1 (A) Anisocoria with dilated right pupil. (B) Absent near response of right pupil.

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In view of anisocoria, diluted pilocarpine (0.125%) test was done that showed no change in the size of pupil [[Figure 2]] whereas instillation of 1% pilocarpine caused constriction of right pupil to 3 mm. Rest of the anterior and posterior segment examinations were normal. Visual fields (Humphrey visual fields of 30-2 program) was normal.
Figure 2 (A) No change in pupil size with 0.125% pilocarpine. (B) Constriction of right pupil with 1% pilocarpine.

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Diagnosis of (OD) internal ophthalmoplegia was made. MRI brain and orbits with contrast were ordered. T2 FS FLAIR, DWI, ADC, and SW1 sequences, 3D TOF MRA through circle of Willis, coronal and axial T2 FSE through orbits, and CISS 3D, 3D T2 TRUFI, and T1 MPR sequences through orbits were taken.

Imaging reports showed right PCA (P1 segment) looping over right 3rd cranial nerve without angulation or kinking of nerve. There was no evidence of mass lesion or aneurysm. MRA was normal. Incidental pituitary gland enlargement reaching the undersurface of the chiasm was noted.

The child was referred to a neurologist and neurosurgeon for further evaluation. Serum ANA, ANCA, lupus anticoagulant, homocysteine, and lipid profile were evaluated to rule out systemic vasculopathy. All investigations were within normal limits except for raised LDL level.

The repeat MRI done, however, confirmed with the previous MRI reports. The boy was prescribed uniocular reading glasses to aid his academics.

On subsequent bimonthly and then six monthly follow-up visits, there was neither change of size of pupil in the right eye nor features of supersensitivity. No features of external ophthalmoplegia were noted.

Two-year follow-up showed no change in pupil of the right eye with no features of super/hypersensitivity to dilute pilocarpine nor features of external ophthalmolegia.

  Discussion Top

The patient’s symptoms of diminution of near vision along with examination findings of fixed and dilated pupil with absent light near dissociation and constriction to 1% pilocarpine along with normal extraocular movements, goes well in favor of the internal ophthalmoplegia.[1],[2] Absence of light-near dissociation and supersensitivity to diluted pilocarpine rules out Adie’s pupil as possibility.[1],[2]

Internal ophthalmoplegia, term coined by Hutchinson, includes iridoplegia and cycloplegia. It is a diagnostic challenge when it occurs in isolation.

Patients with anisocoria and poorly reactive pupil, that is, internal ophthalmoplegia, should be evaluated for ipsilateral III nerve palsy. Sunderland[7] reported that dilated pupil in isolation or with minimal 3rd cranial nerve paresis may be caused by extraaxial lesion compressing III nerve, but such presentation is rare to occur in isolation.

Intrinsic lesions like neurinoma of III nerve can present as isolated internal ophthalmoplegia initially followed by late involvement of extraocular muscle as late as 17 years.[8],[9]

Arachnoid cysts also can cause slow progression and compression of III nerve initially presenting as only pupillary involvement.[10]

Recently, vascular compression as a cause of such isolated unilateral pupillary involvement has been reported.[5],[6] Observational study of five cases with only internal ophthalmoplegia showed neurovascular conflict between III nerve, posterior communicating artery, and clinoid process as the possible cause.[5]

Isolated 3rd cranial nerve palsy secondary to posterior intracranial circulation anatomical variants have been reported. In fact, the cause has been localized to aberrant course of posterior cerebral artery in these nine cases and is nonaneurysmal. Interestingly, most of them were spontaneously resolved. The authors concluded that these anatomical variations are rare but possible causes of 3rd cranial nerve palsy.[6]Our case also showed right PCA (P1 segment) looping over right III nerve similar to MRI features as reported by Tan et al.[11] but with no evidence of compression of III nerve.

Our case is unique in its presentation as internal ophthalmoplegia and remaining status quo at 2 years follow-up unlike other cases reported in the literature. This we presume to be probably idiopathic in nature.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Walsh FB, Hoyt WF. Clinical neuro-ophthalmology. 3rd ed. Vol. 1. Baltimore, MD: Williams & Wilkins, 1969 pp. 425-8, 500-11.  Back to cited text no. 1
Thompson HS, Pilley SEJ. Unequal pupils. A flow chart for sorting out the anisocorias. Surv Opthalmol 1976;21:45-8.  Back to cited text no. 2
Radziwill AJ, Steck AJ, Borruat FX, Bogousslavsky J. Isolated internal ophthalmoplegia associated with IgG anti-GQ1b antibody. Neurology 1998;50:307.  Back to cited text no. 3
Sato H, Naito K, Hashimoto T. Acute isolated bilateral mydriasis: case reports and review of the literature. Case Rep Neurol 2014;6:74-7.  Back to cited text no. 4
Albayram S, Ozer H, Sarici A, Murphy K, Miller N. Unilateral mydriasis without ophthalmoplegia: a sign of neurovascular compression? Case report. Neurosurgery 2006;58:E582-3.  Back to cited text no. 5
Trechot F, Tonnelet R, Conart JB, Legou F, Braun M, Angioi K. Mydriasis revealing vascular and osteodural compression of the oculomotor nerve: an observational study on five cases. J Fr Ophtalmol 2016;39:491-7.  Back to cited text no. 6
Sunderland S. Mechanism responsible for changes in the pupil unaccompanied by disturbances of extraocular muscle function. Br J Ophthalmol 1952;36:638-44.  Back to cited text no. 7
Kaye-Wilson LG, Gibson R, Bell JE, Steers AJW. Oculomotor nerve neurinoma, early detection by magnetic resonance imaging. Neuro-ophthalmology 1994;14:37-41.  Back to cited text no. 8
Wilhelm H, Klier R, Toth B, Wilhelm B. Oculomotor nerve paresis starting as isolated internal ophthalmoplegia. Neuro-ophthalmology 1995;15:211-5.  Back to cited text no. 9
Hustler A, Joy H, Hodgkins P. Isolated unilateral mydriasis with delayed oculomotor nerve palsy secondary to intracranial arachnoid cyst. J AAPOS 2009;13:308-9.  Back to cited text no. 10
Tan T, Tee JW, Wang YY. Oculomotor nerve palsy secondary to 10aberrant posterior cerebral artery. BMJ Case Rep 2014.  Back to cited text no. 11


  [Figure 1], [Figure 2]


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