A gas-permeable contact lens should be considered if the patient:

• • Has had a long, successful history of gas-permeable lens wear. Otherwise, these patients may experience a longer adaptation period due to the rigid nature of GP lenses.
  • Desires to have excellent optical clarity at a distance and near, especially if astigmatic.
  • Is not involved in activities and /or hobbies that require rapid eye movement.
  • Has more significant corneal irregularities, such as keratoconus or irregular astigmatism.
  • Desires a more cost-effective lens. Although they require specialized cleaning and handling techniques, their longevity can save costs over time.

Corneal topography can also be used to determine which lens could be used. When prescribing gas-permeable lenses, an aspheric design can be used on a cornea with a central apex, and a segmented/translating design can used on an inferior-positioned apex.⁴

• Aspheric Multifocal Designs
  • • Early-to-moderate presbyopes are best suited with this design and patients who need better distance and intermediate vision.
    • Near and distance optics are present within the pupil simultaneously (simultaneous vision), so it is best suited for patients with intermediate distance demands such as computer usage at eye level.
    • More successful in patients with small-to-medium pupils (less than 5mm) because of the effects of glare and ghosting in the plus periphery.
    • Early presbyopes who were previous gas permeable lens wearers will adapt easily from a thin spherical design into a relatively thin aspheric design
    • Recommended for patients who are not good segmented, translating candidates (i.e., flaccid lower lid and/or an inferiorly positioned lid)
• Segmented, Translating Designs
  • • Provide excellent distance and near vision as any add power can be incorporated into the lens
    • Good option for moderate-to-advanced presbyopes, especially if the patient is unable to achieve satisfactory vision with an aspheric lens design.
    • Utilize prism or truncation to use the lower lid such that when the patient looks inferiorly to read, the lens is pushed up so that the patient is viewing through the reading add power of the lens.
    • The segments are available in executive, crescent, and D-shaped. They are fit on flat or flatter than “K” to allow the lower lid to interact with the lens during downward gaze. The best anatomical traits for these lenses are:
      • • An upper lid that just covers the upper limbus or is above the upper limbus so that there is limited upper lid interaction.
        • A lower lid 1mm to 1.5mm below or tangent to the limbus with a tight lower lid tension.
        • Any pupil size but a smaller pupil is preferred to avoid high segment heights, excessive translation, or a decentered corneal apex.

• It is important to understand the pros and cons of each modality to meet every patient’s needs. These include soft, gas permeable, hybrid, and scleral lenses.
• Prescribing well-fitted gas-permeable lenses will lead to loyal patients with excellent comfort, vision, and eye health, which is both professionally and financially rewarding.