title: Direct image-creating aspheric lens for indirect ophthalmoscopy.
abstract: OBJECTIVE
  To describe a compact handheld optical lens that creates a real, upright image of the fundus with indirect ophthalmoscopy.
  
  
  METHODS
  The compound lens consists of three double aspheric lenses of variable dioptric power mounted coaxially in a plastic housing mount. Lens A and B are separated by a distance of 30.96 mm while lens B and C are 19.38 mm apart. The length of the optical system is 79.63 mm.
  
  
  RESULTS
  The lens design provides an upright aerial image of the fundus between the lens and the observer compared to the real inverted image formed by conventional indirect lenses during indirect ophthalmoscopy.
  
  
  CONCLUSIONS
  The direct image-creating aspheric lens provides an upright image of the fundus with binocular indirect ophthalmoscopy, thus eliminating the need for mental reorientation of an inverted image.
authors.affiliation: Department of Ophthalmology, University of Florida College of Medicine, Jacksonville, FL 32209, USA.
authors.forename: Kakarla V
authors.initials: KV
authors.lastname: Chalam
authors.forename: Vikram S
authors.initials: VS
authors.lastname: Brar
authors.forename: Swati
authors.initials: S
authors.lastname: Agarwal
mesh_terms: D004867:Equipment Design; D005654:Fundus Oculi; D006801:Humans; D007909:Lenses; D019721:Ophthalmoscopes; D009887:Ophthalmoscopy / Q000379:methods*