Report of a study of prevalence of refractive error in Central Government employees.

Eitemau Tebyg

• Refraction of the human eye and methods of estimating the refraction, including a section on the fitting of spectacles and eye-glasses, etc
  gan: Thorington, James, 1858-1944
  Cyhoeddwyd: (1916)
• Refraction of the human eye and methods of estimating the refraction, including a section on the fitting of spectacles and eye-glasses, by James Thorington
  gan: Thorington, James, 1858-1944
  Cyhoeddwyd: (1930)
• Lectures on the errors of refraction and their correction with glasses
  gan: Valk, Francis
  Cyhoeddwyd: (1889)
• Refraction of the eye; its diagnosis and the correction of its errors. with a chapter on the use of prisms
  gan: Morton, A. Stanford
  Cyhoeddwyd: (1906)
• Lectures on the errors of refraction and their correction with glasses : delivered at the New York post-graduate medical school, with illustrative cases from practice, both private and clinical
  gan: Valk, Francis
  Cyhoeddwyd: (1895)