First Responders
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Introduction
Specific vision requirements to meet the eligibility for employment are variable among different first responder disciplines. To meet these standards, it is generally accepted that contact lenses can be used as a method of vision correction. However, some agencies have a blanket legacy policy prohibiting the use of any hard or rigid contact lenses due to their potential for dislodgement from the eye. We seek to clarify the types of rigid contact lenses and refute the exclusion of scleral contact lens wear based on the potential for dislodgement.
Position
Rigid gas permeable (GP) contact lenses can be classified into three categories: corneal GP’s, hybrid contact lenses, and scleral GP lenses. Corneal GP lenses rest on the corneal surface and typically have a diameter of 12.0 mm or smaller. Although they align to the corneal curvature, they do not create a seal to the corneal surface, and they may interact with the eyelids. In extreme positions of gaze or in the event of significant physical contact, a corneal GP lens could eject or dislodge from the eye. Hybrid contact lenses have a GP lens center with a soft contact lens skirt that are bonded together. This provides the optics of GP lens, while using the soft lens to align to the ocular surface beyond the corneal diameter. The soft lens skirt maintains a semi-seal allowing the lens to maintain stability and centration. Scleral GP lenses are larger diameter GP lenses that range between 14.0 and 22.0 mm in diameter. They vault over the corneal surface and align to the sclera (white of the eye) and bulbar conjunctiva.
Although scleral GP lenses may fall under the umbrella of rigid lenses, it is our position that rigid lenses should be reclassified to separate categories of corneal GP’s and hybrid/scleral GP’s. It is accepted that GP lenses have superior optics to soft contact lenses1, so it’s reasonable to assume that any exclusion of rigid lenses is due to potential for dislodgement. Alignment of the scleral lens to the sclera allows for lens centration and stable optics as well as superior comfort2. The semi-seal created by this alignment also effectively eliminates lens movement and eyelid interact that would contribute to lens dislodgement. Therefore, our position maintains there is no greater risk of dislodgement with a scleral GP lens than a soft contact lens. Provided all other vision requirements are met, candidates wearing scleral lenses should not be immediately excluded from eligibility.
