BIO

• What are the characteristics of the images produced by Direct and BIO methods?

  • Direct:
  • Virtual image
  • Upright orientation
  • No stereopsis
  • ~5° field of view
  • ~15x magnification
  • BIO:
  • Real image
  • Reversed & inverted orientation
  • Yes stereopsis
  • 25° field of view
  • 2x magnification
• What is the limitation of the Direct method?

  Equator
• What is the limitation of the BIO method?

  Posterior pole, equator to ora serrata, and vitreous
• What are the indications for using BIO?

  • Thorough ocular fundus exam
  • Reduced best corrected visual acuity or visual field
  • Reported visual disturbances (e.g., photopsia, floaters)
  • History of diabetes, hypertension, cancer, etc.
  • Known PVD or retinal lesions
  • Cataract examination
• What are the advantages of using BIO?

  • Provides 2x magnification
  • Stereopsis
  • Large field of view (8DD)
  • Potential to view entire retina
  • Better view through media opacities
  • Portable and requires less patient cooperation
• What are the disadvantages of using BIO?


  • Lower magnification than fundus lens
  • Image is reversed and inverted
  • Requires mydriasis
  • Illumination may be uncomfortable for the patient
• What is the basic optics of BIO?

  • Fundus illuminated and reflected light observed
  • Light rays focused using a high plus condensing lens
  • Image is real, inverted, and reversed
  • Examiner views image through oculars of an indirect ophthalmoscope
• What are the features of BIO instrumentation?

  • Head/spec mounted for hands-free use
  • Built-in +2.00 lens
  • Variable pupil distance
  • Fixed aperture sizes (small, medium, large)
  • Optional filters (red free, cobalt blue)
• What are the characteristics of condensing lenses used in BIO?

  • Handheld, usually +20D or +2.2D
  • Range from 5.5 to 40D
  • Different types for various pupil sizes
  • Clear or amber tint available

  
• What is the procedure for performing BIO?

  Position equipment comfortably, adjust eyepieces, and inform the patient.
• What adjustments should be made during the BIO procedure?

  • Adjust PD for the same field of view
  • Use appropriate aperture size based on pupil dilation
  • Dim lights for better visibility
  • Provide gaze direction to the patient
• What should be done if the image does not fill the lens during BIO?

  Move the lens in/out and adjust the position.
• What troubleshooting steps can be taken for alignment issues in BIO?

  • Check light direction through the pupil
  • Anchor fingers against the patient for stability
  • Ensure light is perpendicular to the lens
  • Adjust working distance as needed
• How should the retina be examined during BIO?

  • Examine in different gaze positions
  • Maintain perpendicularity to the area being observed
  • Systematically move around to view surrounding retina
• What should be recorded after a BIO examination?

  • Drops used (name, %, dose, eye, time)
  • Techniques performed
  • Findings in mid-periphery and periphery
  • Abnormalities noted (size, shape, color, location)
• What is the purpose of scleral indentation during BIO?

  • Used for suspected retinal tears or holes
  • Elevates the retina for better visibility
  • Allows examination of nasal and temporal quadrants