Reduction in retinal nerve fiber layer thickness in tuberous sclerosis complex.

Area of Science:

• Neuroscience
• Ophthalmology
• Genetics

Background:

• Tuberous sclerosis complex (TSC) is associated with diffuse white matter abnormalities, including axonal disorganization, altered myelination, and gliosis.
• Non-invasive assessment of central nervous system (CNS) axonal integrity is crucial for understanding TSC pathophysiology.
• Optical coherence tomography (OCT) offers a non-invasive, cost-efficient method for evaluating retinal morphology and retinal nerve fiber layer (RNFL) thickness.

Purpose of the Study:

• To investigate central nervous system (CNS) axonal integrity in patients with tuberous sclerosis complex (TSC) using non-invasive methods.
• To assess RNFL thickness in TSC patients and compare it with healthy controls.
• To explore the potential of OCT as a biomarker for axonal alterations in TSC.

Main Methods:

• Eight subjects diagnosed with TSC were evaluated using OCT to measure RNFL thickness.
• A control group of age- and sex-matched healthy individuals was included for comparison.
• RNFL thickness was analyzed, particularly in the temporal quadrant, between the TSC and control groups.

Main Results:

• Patients with TSC exhibited significantly reduced mean overall RNFL thickness compared to healthy controls.
• The temporal quadrant showed a statistically significant difference in RNFL thickness (TSC: 62.5 ± 6.9 vs. Control: 76.9 ± 5.4; p < 0.0001).
• These findings suggest a measurable impact of TSC on axonal integrity within the retina.

Conclusions:

• Reduced RNFL thickness in TSC patients may indicate chronic axonal degeneration or impaired neuronal development.
• The results support the hypothesis of diffuse axonal alterations in TSC, potentially more widespread than previously recognized.
• Observed RNFL thinning could be a manifestation of early neurodevelopmental abnormalities driven by mammalian target of rapamycin (mTOR) overactivation in TSC.