CASE 16796 Published on 22.06.2020

Myopic Strabismus Fixus (Heavy Eye Syndrome HES) as a cause of intermittent diplopia.

Section

Head & neck imaging

Case Type

Clinical Cases

Authors

Dr. Simon Gatt1, Dr. Adrian Mizzi2 , Dr. Francis Zarb3

1Higher Specialist Trainee, Medical Imaging Department, Mater Dei Hospital, Malta

2Consultant Radiologist, Medical Imaging Department, Mater Dei Hospital, Malta.

3Seniour Lecturer, Department of Radiography, Faculty of Health Sciences, University of Malta, Malta.

Patient

71 years, male

Categories
Area of Interest Eyes, Head and neck ; Imaging Technique MR
Clinical History

71-year-old gentleman with circa 4-month history of frontal headaches and diplopia, worse while watching TV. Headaches are described as persistent and interfering with the patient’s normal sleep pattern. Recent brain CT showed no acute intracranial pathology or space-occupying lesions within the brain. MRI performed.

Imaging Findings

High-resolution MR imaging shows irregular posterior elongation of the globes, in keeping with advanced myopic changes. The globes also demonstrate an element of superolateral displacement with respect to the bony orbit (Fig. 1).

Thinning and displacement of the lateral rectus – superior rectus (LR-SR) muscle band is seen, as well as inferior and nasal displacement of the lateral rectus and superior rectus muscles respectively on both sides (Fig. 2).

Dislocation angles (measured as the angle formed by the central points of the lateral rectus and superior rectus muscles with that of the globe) were abnormal measuring between 113-125 degrees (Fig. 3).

Discussion

Background: HES is a rare sequela of individuals who suffer from severe myopia which can result in a form of strabismus which classically presents as an intermittent horizontal diplopia [4]. The term ‘heavy eye’ originates from a previous misconception that the symptomatology was a result of a ‘heavier’ globe which drooped anteriorly [4]. It is now believed to be the result of superotemporal herniation of the posterior part of the globe through the lateral conal musculature which in turn causes dysfunction of the normal muscular pull of the superior and lateral recti of the orbit which in turn show medial and inferior deviation respectively as a consequence.

Clinical Perspective: Typically, patients would be heavily myopic which results in distortion of the normal globe architecture thus leading to the aforementioned muscular disruption and esotropia (where one or both eyes turn inward in an intermittent or permanent state) [2-3]. The current diagnostic gold-standard is cross-sectional imaging (usually MRI) which provides accurate anatomical delineation of the orbital musculature and thus identification of any discrepancy.

Imaging Perspective: The key imaging findings are seen on high resolution cross-sectional multiplanar reformats (typically MRI). Unilateral or bilateral globe enlargement is seen (in keeping with ocular myopia), often with focal posterior prolapsing in the superotemporal direction [2-3]. Coronal views (specifically T1W) at a level just off the posterior equator of the globe allow for optimal visualisation of the extraocular muscles, specifically of the lateral and superior recti [4]. In HES, there is medial deviation of the superior rectus and inferior deviation of the lateral rectus with consequent widening of the normal 90° angle they normally form with respect to the centre of the globe (thus giving a wide dislocation angle) [3-4]. Imaging also allows identification of the LR-SR band, a strip of collagenous fibres which connect the superior and lateral recti. In HES this band is often thinned or can even show focal disruption, a process which is believed to be secondary to abnormal compression of the conus with the lateral orbital wall [2, 4].

Outcome & Teaching Points: Surgical correction is often employed nowadays to correct this abnormality, where the fibres from the superior and lateral recti are anastomosed (partial Jensen’s procedure), restoring their normal position with relation to the globe and effectively correcting the strabismus with a relatively safe and simple procedure [1,5]. It is therefore an important radiological diagnosis to make in these patients as their quality of life will be markedly improved following treatment.

Written patient consent for this case was waived by the Editorial Board. Patient data may have been modified to ensure patient anonymity.

Differential Diagnosis List
Raised intraocular pressure (congenital vs acquired) giving macrophthalmus.
Coloboma (producing a focal discontinuity in the eyeball).
Final Diagnosis
Raised intraocular pressure (congenital vs acquired) giving macrophthalmus.
Case information
URL: https://www.eurorad.org/case/16796
ISSN: 1563-4086