In spite of almost constant illness brought about by eyestrain, he accomplished more than most well men have done.
He, therefore, constantly tries to improve it by changing the tension of his ciliary muscles, and so brings on eyestrain.
Then eyestrain and headache and a touch of fever followed, and I cast about for means to ameliorate my bodily ills.
eyestrain eye·strain (ī'strān')
Pain and fatigue of the eyes, often accompanied by headache, due to prolonged use of the eyes, uncorrected defects of vision, or an imbalance of the eye muscles. Also called asthenopia.