Morphology and microcirculation changes of the optic nerve head between simple high myopia and pathologic myopia

Area of Science:

• Ophthalmology
• Medical Imaging
• Myopia Research

Background:

• High myopia (HM) encompasses both simple high myopia (SHM) and pathologic myopia (PM).
• Pathologic myopia is associated with significant ocular structural changes, including those at the optic nerve head (ONH).
• Understanding ONH morphology and microcirculation differences between SHM and PM is crucial for identifying early signs of PM progression.

Purpose of the Study:

• To investigate and compare morphological and microcirculation changes of the optic nerve head (ONH) in simple high myopia (SHM) and pathologic myopia (PM).
• To identify specific ONH alterations indicative of PM development.

Main Methods:

• A cross-sectional study included 193 patients with high myopia (HM).
• Optical coherence tomography (OCT) and fundus photography were used to assess ONH parameters, peripapillary atrophy (PPA), retinal nerve fiber layer (RNFL) thickness, choroidal thickness (PCT), scleral thickness (PST), and vessel density (PVD).
• Patients were categorized into SHM (138 eyes) and PM (55 eyes) groups for comparative analysis.

Main Results:

• Pathologic myopia patients were older with higher diopter and longer axial length (AL) compared to SHM.
• PM eyes showed a smaller angle α, increased disc-fovea distance (DFD), larger PPA area, thinner peripapillary choroidal thickness (PCT), and reduced peripapillary vessel density (PVD).
• Superior and inferior peripapillary retinal nerve fiber layer (PRNFL) thickness was reduced in PM, while temporoinferior PRNFL was increased.

Conclusions:

• Pathologic myopia is characterized by specific ONH morphological and microcirculatory differences compared to SHM, including thinner PCT and lower PVD.
• An enlarged PPA area relative to ONH area may indicate the presence of PM.
• Ophthalmologists and patients should monitor ONH morphology and microcirculation changes, as these may precede overt morphologic alterations in PM development.