PURPOSE:

To explain the mechanism for acquired enophthalmos after ventriculoperitoneal shunting (VPS).

DESIGN:

Case series and a case-control study.

PARTICIPANTS AND CONTROLS:

Four study patients with bilateral enophthalmos after VPS and 10 control subjects.

METHODS:

Case description of 4 study patients. Calculated orbital volumes for 2 study patients were compared with controls using the Wilcoxon rank-sum test.

MAIN OUTCOME MEASURES:

Exophthalmometry measurements and total orbital and fat volumes.

RESULTS:

Patient 1 is a 25-year-old man who presented with progressive enophthalmos 3 years after VPS for traumatic intracranial bleeding. Imaging demonstrated upward expansion of the orbital roof and evidence of intracranial hypotension. The intracranial pressure (ICP) was 20 mm H₂O. The enophthalmos improved after shunt revision. Patient 2 is a 19-year-old man who presented with progressive enophthalmos 18 months after VPS for traumatic intracranial hemorrhage. Patient 3 is a 38-year-old woman who presented with bilateral enophthalmos 15 years after VPS after a ruptured aneurysm. Imaging showed orbital expansion. Patient 4 is a 16-year-old man who presented with severe enophthalmos 5 years after a VPS for aneurysm-related hemorrhage. Imaging demonstrated orbital enlargement and findings of intracranial hypotension. Intracranial pressure ranged between -200 and 0 mm H₂O. Shunt revision improved the enophthalmos. Total orbital volumes were significantly greater in the study patients than in the controls. Control subjects (5 male, 5 female, ages 23-45 years) had an average right orbital volume of 24.6 ± 3.3 cm³ (n = 10). In comparison, the right orbital volumes of patients 1 and 3 were 32.6 and 32.1 cm³. Similar results were found for the left orbits (23.9 ± 2.7 cm³ [control average] vs. 35.9 and 32.6 cm³). In patient 1, the post-shunt volumes increased 14% (right) and 23% (left) from pre-shunt volumes. In contrast, orbital fat volume was not statistically significantly different between the control group and enophthalmic patients (right orbit control mean 7.94 ± 3.1 cm³ [n = 10] vs. 7.9 and 9.8 cm³; left orbit control mean 7.88+3.1 cm³ vs. 9.2 and 10.0 cm³).

CONCLUSIONS:

Enophthalmos after VPS results primarily from chronic intracranial hypotension. Low ICP causes expansion of orbital volume with no fat atrophy. In such patients, shunt revision with a pressure-regulating valve to correct intracranial hypotension should be considered.

FINANCIAL DISCLOSURE(S):

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Copyright © 2011 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.