title: Topographic analyses of shape of eyes with pathologic myopia by high-resolution three-dimensional magnetic resonance imaging.
abstract: OBJECTIVE
  To analyze the topography of human eyes with pathologic myopia by high-resolution magnetic resonance imaging (MRI) with volume rendering of the acquired images.
  
  
  METHODS
  Observational case series.
  
  
  METHODS
  Eighty-six eyes of 44 patients with high myopia (refractive error ≥-8.00 diopters [D] or axial length >26.5 mm) were studied. Forty emmetropic eyes were examined as controls.
  
  
  METHODS
  The participants were examined with an MRI scanner (Signa HDxt 1.5T, GE Healthcare, Waukesha, WI), and T(2)-weighted cubes were obtained. Volume renderings of the images from high-resolution 3-dimensional (3D) data were done by computer workstation. The margins of globes were then identified semiautomatically by the signal intensity, and the tissues outside the globes were removed.
  
  
  METHODS
  The 3D topographic characteristic of the globes and the distribution of the 4 distinct shapes of globes according to the symmetry and the radius of curvature of the contour of the posterior segment: the barrel, cylindric, nasally distorted, and temporally distorted types.
  
  
  RESULTS
  In 69.8% of the patients with bilateral high myopia, both eyes had the same ocular shape. The most protruded part of the globe existed along the central sagittal axis in 78.3% of eyes and was slightly inferior to the central axis in the remaining eyes. In 38 of 68 eyes (55.9%) with bilateral pathologic myopia, multiple protrusions were observed. The eyes with 2 protrusions were subdivided into those with nasal protrusions and those with temporal protrusions. The eyes with 3 protrusions were subdivided into nasal, temporal superior, and temporal inferior protrusions. The eyes with visual field defects that could not be explained by myopic fundus lesions significantly more frequently had a temporally distorted shape. Eyes with ≥2 protrusions had myopic chorioretinal atrophy significantly more frequently than eyes with ≤1 protrusion.
  
  
  CONCLUSIONS
  Our results demonstrate that it is possible to obtain a complete topographic image of human eyes by high-resolution MRI with volume-rendering techniques. The results showed that there are different ocular shapes in eyes with pathologic myopia, and that the difference in the ocular shape is correlated with the development of vision-threatening conditions in eyes with pathologic myopia.
  
  
  BACKGROUND
  The author(s) have no proprietary or commercial interest in any materials discussed in this article.
authors.forename: Muka
authors.initials: M
authors.lastname: Moriyama
authors.forename: Kyoko
authors.initials: K
authors.lastname: Ohno-Matsui
authors.forename: Kengo
authors.initials: K
authors.lastname: Hayashi
authors.forename: Noriaki
authors.initials: N
authors.lastname: Shimada
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yoshida
authors.forename: Takashi
authors.initials: T
authors.lastname: Tokoro
authors.forename: Ikuo
authors.initials: I
authors.lastname: Morita
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001699:Biometry; D005123:Eye / Q000473:pathology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D047728:Myopia, Degenerative / Q000473:pathology*; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology