Model-based improvements in the treatment of patients with strabismus and axial high myopia.
OBJECTIVE
Eye motility disorders with axial high myopia and an enlarged globe are often characterized by a hypotropia of the affected eye, usually referred to as heavy-eye syndrome. Based on an intuitive interpretation of magnetic resonance (MR) images, the cause of the hypotropia has typically been assigned to the rectus muscles. In this study, the hypothesis that the oblique muscles play an important role in the underlying biomechanical disorder of this type of strabismus was investigated.


METHODS
The hypothesis was tested by (1) a retrospective analysis of surgical results in one patient with unilateral axial high myopia; and (2) MR images of orbital tissues in two further patients with unilateral axial high myopia.


RESULTS
MR images demonstrated a pattern of extraocular muscle path displacements similar to those described previously, but also a uniform decrease in the cross-sectional area of the inferior oblique muscles. Computer modeling required decreased inferior oblique contractility in addition to displaced extraocular muscle paths to recreate the observed motility pattern accurately.


CONCLUSIONS
Patients with axial high myopia regularly show a reduction in the diameter of the inferior oblique. The resultant reduction in muscle-strength is important for the correct explanation of this complex eye movement disorder.
Hoerantner
Robert
R
Department of Ophthalmology, Krankenhaus der Barmherzigen Schwestern (Good Sisters Hospital), Ried, Austria.
Kaltofen
Thomas
T
Priglinger
Siegfried
S
Fock
Christian-Michael
CM
Buchberger
Michael
M
Haslwanter
Thomas
T
D000328:Adult; D003198:Computer Simulation; D005133:Eye Movements / Q000502:physiology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D009801:Oculomotor Muscles / Q000503:physiopathology / Q000601:surgery*; D012189:Retrospective Studies; D013285:Strabismus / Q000503:physiopathology / Q000601:surgery*; D013577:Syndrome; D013709:Tendon Transfer