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To the Editor:
—The purpose of this communication is to clarify a minor but significant point in the physiology of vision. The subject is not clearly presented in some of the most widely used textbooks on ophthalmology, as evidenced by inquiries which I have received. A typical inquiry is this: "Which author is correct—Duke-Elder, who states in his `Text-Book of Ophthalmology,' volume 1, page 755, that the retinal image is increased during accommodation, or Cowan, who says in `Refraction of the Eye,' page 147, that the retinal image is decreased during accommodation?"An examination of the material referred to shows that in a sense both authors are correct, but what they wanted to explain has not been fully and adequately presented. Dr. Cowan states, page 147:In accommodation the dioptric power is increased and the principal focal distances are shortened. The retinal image, therefore, is decreased in size during accommodation.
Pascal JI. ACCOMMODATION AND RELATIVE IMAGE SIZE. Arch Ophthalmol. 1950;43(1):142-143. doi:10.1001/archopht.1950.00910010147009