Relationship between Three-Dimensional Magnetic Resonance Imaging Eyeball Shape and Optic Nerve Head Morphology

Area of Science:

• Ophthalmology
• Optometry
• Medical Imaging

Background:

• The optic nerve head (ONH) is crucial for vision, and its structural integrity is vital.
• Variations in ONH morphology can impact visual function and are relevant in diseases like glaucoma.
• Understanding the factors influencing ONH structure, such as eyeball shape, is important for diagnosis and management.

Purpose of the Study:

• To investigate the association between three-dimensional (3D) eyeball shape and the positioning of the central retinal vascular trunk (CRVT) and externally oblique border (EOB) within the optic nerve head (ONH).

Main Methods:

• A prospective, cross-sectional study involving 56 subjects (112 eyes) diagnosed with glaucoma or glaucoma suspect.
• 3D magnetic resonance imaging (MRI) was used to classify eyeball shape (prolate, horizontally oblate, vertically oblate).
• Optical coherence tomography (OCT) measured the deviation of the CRVT from the Bruch's membrane opening (BMO) center and the angular location of the longest EOB.

Main Results:

• The CRVT's angular deviation varied significantly with eyeball shape: nasal in prolate, temporal in horizontally oblate, and vertical in vertically oblate shapes.
• The EOB's longest axis was consistently located opposite to the CRVT's position (P < 0.001).
• Temporal CRVT location was associated with older age, nasal EOB, and oblate eyeball shapes (P < 0.001 for both).

Conclusions:

• The 3D eyeball shape is significantly associated with the positions of the CRVT and EOB in the ONH.
• Diverse eyeball expansion patterns during growth may lead to variations in the spatial relationship between the lamina cribrosa (LC) and BMO in adults.
• These findings highlight the influence of overall ocular geometry on optic nerve head structure.