Surgery and Tissue Preparation

Strabismus correction by unilateral R&R procedure was done by the same surgeon (A.P.), under peribulbar block or general anesthesia, using standard procedure proposed by Parks et al.³⁴ Surgical dosage was based on the maximal deviation angle. In our cases, we preferred to limit recessions and resections up to 8 mm. Large recessions or resections cause alteration in the palpebral aperture of the eyes and eye motility, including lateral incomitance.³⁵ The full width strip of rectus muscles excised during strabismus were immediately immersed in a fixative solution of 2.5% glutaraldehyde and stored in a refrigerator at a temperature of 10 C in the Human tissue Bank in Chisinau, Moldova, for a minimum of 1 week before further preparation.

After washing, muscle samples were immersed in a 1% solution of unbuffered Osmium Tetroxide for 1 hr., then dehydrated in graded ethanol, cleared in Xylene, and embedded in Araldite. Serial transverse sections were cut on an ultramicrotome with a thickness of 0.75 µm, then mounted on glass slides and stained with Toluidine blue. The initial cut was obtained from the distal end of the tissue (containing pure tendon), and advanced towards the proximal end of the tissue (containing muscle fibres). Every 5 to 8 sections were examined until reaching the first evidence of muscle fibres and thereafter complete serial sections through all identified neuromuscular structures.