A practical guide to the study of the diseases of the eye : their medical and surgical treatment / by Henry W. Williams.

  • Williams, Henry W. (Henry Willard), 1821-1895.
Date:
1873
Catalogue details

Licence: Public Domain Mark

Credit: A practical guide to the study of the diseases of the eye : their medical and surgical treatment / by Henry W. Williams. Source: Wellcome Collection.

Provider: This material has been provided by the Harvey Cushing/John Hay Whitney Medical Library at Yale University, through the Medical Heritage Library. The original may be consulted at the Harvey Cushing/John Hay Whitney Medical Library at Yale University.

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    lowed weaker glasses at first, — sometimes of even less power than suited him previous to the use of atro- pia, — their strength being afterwards increased, as his habit of continuous accommodation is gradually laid aside, till he reaches the power which is equivalent to the amount of his hypermetropia. Theoretically, it is for the advantage of the hyper- metrope to wear his glasses constantly, even for dis- tant sight, — as he thus avoids tasking his accommoda- tive power for such purposes, but keeps it in reserve for near vision. But few persons are willing to do this, inasmuch as vision is very often perfect at a dis- tance without glasses, and in nearly all cases the pa- tient is able, at least during early life, to discern large objects sufficiently well for most purposes. Where, however, there is a high degree of the affection, its subjects usually resign themselves, even from youth, to the use of glasses, and nearly always in advanced age require two pairs, the weaker for distant vision and the stronger for reading. The latitude of accommodation may be tested by first adapting to the eye such glasses as completely neutralize the hypermetropia, and then measuring the nearest point at which small objects can be distinctly seen. A high degree of hypermetropia is by no means rare in childhood, and is often hereditary. Its exist- ence or absence should always be determined by an examination if the eyes readily become fatigued by