Strength is defined as the amount of stress a material can withstand before fracturing. Therefore, the more strength a material has, the more durable it is. Thus, a toric lens should be constructed from a material with high strength.

Every time I read this to myself, it sounds badly worded. How could I word this better?

As strength is defined as the amount of stress a material can withstand before fracturing, the material used to construct a toric lens should have a relatively high tolerance to stress. The material tolerance to stress should be relatively high when facing each type of stress, such as shear, compression, and tensile stress. This would allow its user to handle the toric more easily as it would be more durable.

I completely rewrote the paragraph. Does this sound better?

I meant to say "The material's tolerance to stress..." not "The material tolerance."

Strength refers to the ability of a material to withstand stress without breaking or fracturing. Essentially, it measures the durability and resistance of the material. Consequently, when constructing a toric lens, it is preferable to utilize a material with high strength to ensure its long-lasting performance.