Sentence:  Myopia has many pages devoted to it. The author regards as the primary cause of this disease an abnormal extensibility and stretching of the sclera, that there is a sort of <WSD>scleromalacia</WSD>, analagous to osteomalacia, which develops in some persons during the period of their growth, recovers spontaneously in many cases, leaves behind an elongation of the axis of the eye, but lasts for decades in the malignant cases, and occurs sometimes in one eye alone. 
Meaning of the word marked with <WSD> tags:  Degenerative thinning of the sclera.