Bates betont immer wieder 'strain' als Ursache von Fehlsichtigkeit.
Huxley analysiert dieses Phänomen so:
"... -either by trying too hard to do well,
or by feeling unduly anxious about possible mistakes. (S.9)
... - by being too anxious to achieve the desired end. But in seeing, as in all other
psycho-physical skills, the anxious effort to do well defeats its own object; for this
anxiety produces psychological and physiological strains, and strain is
incompatible ...