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Microscopic and ultrastructural changes of Müller's muscle in patients with simple congenital ptosis
Mohammed D Alshehri1, Yasser H Al-Fakey, Hisham M Alkhalidi
1Departments of *Ophthalmology and †Pathology, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia.
Purpose:
To study microscopic and ultrastructural changes of Müller's muscle in patients with isolated congenital ptosis.
Methods:
In this prospective, observational case-control study, Müller's muscle specimens were collected during ptosis surgical correction for 18 consecutive patients. Each specimen was divided into 2 parts. One part was embedded in formalin for light microscopy, and the other one was fixed in 3% glutaraldehyde for electron microscopy. A neuropathologist, serving as a masked evaluator, blindly reviewed all the different features for every case and counted the number of myocytes showing distinct myofilaments in the whole grid for every case. Statistical analysis using compare means and correlation tests was conducted to investigate potential associations and/or differences within and across groups.
Results:
Twelve Müller's muscle specimens from patients with simple congenital ptosis of various severities and 6 specimens from patients with aponeurotic ptosis (controls) were collected and studied. Under light microscopy, congenital ptosis slides showed a small number of dispersed myocytes in a fibrotic background, whereas acquired ptosis slides showed a greater number of well-defined myocytes. Under electron microscopy, all congenital ptosis specimens had only a very small number of myocytes with clear, distinct myofilaments. Most myocytes in the aponeurotic ptosis group showed clear, distinct myofilaments, indicating a well-preserved muscle. No relationship existed between the number of clear, distinct myofilaments observed in the congenital ptosis group by transmission electron microscopy and patient age or ptosis severity.
Conclusion:
Substantial Müller's muscle atrophy was observed in patients with different severities of isolated congenital ptosis.
Insights
Müller's muscle in congenital ptosis patients shows significant atrophy, with fewer myocytes and distinct myofilaments compared to controls. This muscle degeneration is evident across various ptosis severities.
Area of Science:
- Ophthalmology
- Histopathology
- Cell Biology
Background:
- Congenital ptosis is a common eyelid condition.
- Müller's muscle plays a crucial role in eyelid elevation.
- Understanding the microscopic changes in Müller's muscle is key to explaining ptosis etiology.
Purpose of the Study:
- To investigate the microscopic and ultrastructural characteristics of Müller's muscle in individuals with isolated congenital ptosis.
- To compare these changes with control groups.
Main Methods:
- Prospective observational case-control study involving 18 patients undergoing ptosis surgery.
- Müller's muscle specimens analyzed using light and electron microscopy.
- Quantitative assessment of myocyte integrity and myofilament presence by a masked neuropathologist.
Main Results:
- Congenital ptosis specimens exhibited dispersed myocytes in a fibrotic background (light microscopy).
- Electron microscopy revealed significantly fewer myocytes with distinct myofilaments in congenital ptosis compared to controls.
- No correlation found between myofilament count and patient age or ptosis severity in the congenital group.
Conclusions:
- Significant Müller's muscle atrophy is a key finding in isolated congenital ptosis.
- These ultrastructural changes likely contribute to the pathophysiology of congenital ptosis.
- The study highlights the degenerative nature of Müller's muscle in this condition.
