Maculopapillary Bundle Degeneration in Optic Neuropathies

Area of Science:

• Neuroscience
• Ophthalmology
• Cell Biology

Background:

• Maculopapillary bundle (MPB) degeneration is a key feature across various optic neuropathies.
• Conditions like nutritional/toxic optic neuropathies, Leber hereditary optic neuropathy (LHON), and dominant optic atrophy (DOA) exhibit MPB-selective degeneration.
• Despite diverse etiologies, these disorders share a common pathway: compromised mitochondrial homeostasis affecting metabolism, biogenesis, and protein synthesis.

Purpose of the Study:

• To comprehensively review the role of the MPB in optic neuropathies.
• To emphasize the critical role of mitochondrial mechanisms in the pathogenesis of these conditions.
• To synthesize current clinical and molecular research on primary MPB disorders.

Main Methods:

• Review of optical coherence tomography (OCT) studies characterizing retinal nerve fiber layer changes.
• Synthesis of clinical and molecular research on primary MPB disorders.
• Analysis of proposed mechanisms, including reactive oxygen species (ROS) generation.

Main Results:

• OCT studies reveal characteristic RNFL changes in mitochondrial optic neuropathies, including selective temporal thinning.
• Mitochondrial dysfunction, leading to ROS generation, is a proposed mechanism for selective MPB atrophy.
• Recent findings indicate MPB degeneration occurs in early glaucoma, with distinct patterns compared to mitochondrial diseases.

Conclusions:

• Mitochondrial dysfunction is a central mechanism in MPB degeneration across various optic neuropathies.
• MPB degeneration in glaucoma presents unique characteristics, challenging previous assumptions.
• Further in-vivo and in-vitro studies are needed to validate the role of ROS in MPB-selective optic neuropathies.