Variation in retinal changes and muscle pathology in mitochondriopathies

Area of Science:

• Ophthalmology
• Neurology
• Genetics

Background:

• Mitochondrial myopathies are a group of disorders affecting muscle function due to mitochondrial dysfunction.
• Retinal changes are increasingly recognized as a manifestation of mitochondrial disorders.
• Classification of certain retinal changes has been limited due to diagnostic challenges.

Purpose of the Study:

• To investigate and characterize the spectrum of ophthalmological findings in patients with mitochondrial myopathies.
• To compare these retinal findings with the underlying myopathic alterations.
• To assess the utility of muscle biopsy in diagnosing generalized mitochondriopathy, especially in cases with severe ocular manifestations.

Main Methods:

• Ophthalmological examinations were performed on a cohort of 12 patients diagnosed with mitochondrial myopathies.
• Muscle biopsies were conducted to identify pathological mitochondria and ragged-red fibers.
• Clinical data on myopathic alterations were collected and compared with ocular findings.

Main Results:

• A wide range of retinal changes, including pigmentary alterations and severe dystrophic changes of the retina, pigment epithelium, and choroid, were observed.
• No clear correlation was found between the severity of retinal pathology and the characteristics of the myopathic changes.
• In two patients with severe chorioretinal dystrophy, generalized mitochondriopathy was not suspected before muscle biopsy confirmation.

Conclusions:

• Retinal and choroidal dystrophic changes can be significant manifestations of mitochondrial myopathies.
• Muscle biopsy is essential for diagnosing mitochondrial myopathies, even in the presence of severe, seemingly isolated, ocular findings.
• These findings expand the spectrum of retinal conditions classifiable under mitochondriopathies.