What are Gas Permeable Contact Lenses?
Gas-permeable contact lenses, also known as GP, RGP, or hard contact lenses, are a type of contact lens that are severely under-rated. Due to their firm material which maintains a smooth curved surface, these lenses provide crisper vision than soft contact lenses. They also offer excellent eye health due to their oxygen permeability, small size, and resistance to harbor bacteria and deposits. They provide correction for myopia, hyperopia, astigmatism, and presbyopia. Specialty GP lenses can be fitted onto eyes that have mild keratoconus, corneal scarring, or who have undergone a corneal transplant as well.
This patient was referred to our office for GP lenses to be free from reading glasses. We provided them with monovision in which one eye is corrected for their near prescription, similar to a monocle.
Due to their ability to maintain their shape, GP lenses can correct for irregular astigmatism. Although this eye has corneal scarring, we were able to correct the vision in this eye to 20/20 with a GP lens that would otherwise be uncorrectable with spectacles or soft lenses.
GP contact lenses are custom-made for each individual prescription. We measure the shape of your cornea and prescribe lenses with the appropriate curvature, size, and prescription power that is necessary. There is no limit to the prescription that they can provide, and we have several patients in our office that are over -20 who wear these lenses. They are also very good at correcting for regular astigmatism without the rotational, shifting effect that soft contact lenses have.
What are the pros and cons of GP lenses vs soft contact lenses?
As you can see, initial comfort is the only area where soft lenses excel over GP contacts. But once you get used to them, GP contacts are comfortable, more durable, easier and less expensive to care for, healthier, and provide crisper vision.
Are these the same kind of hard contact lenses from the past?
No! With advances in manufacturing, gas-permeable contact lenses are made in better materials, thinner designs, larger diameters, and consistently smoother edges than before. They also allow plenty of oxygen transmissibility to the cornea, unlike old hard contact lenses that provided none.
Why haven't I heard of these before/why does no one wear these?
There are a variety of reasons why this may be the case. Soft contact lenses are mass manufactured and easily accessible at any optical shop, whereas a GP lens is custom designed per patient. Soft lenses therefore require little chair time in comparison to fitting GP lenses. For the majority of people, their prescription is low and regular enough that a soft contact lens is a fast and easy option. Unfortunately, prescribing GP lenses has become more of a niche rather than the norm so a specialty fitter may be necessary to fit them. Finally, soft lenses provide immediate comfort rather than needing to go through an adaptation period first to get over the initial lens awareness sensation.
Do GP contact lenses hurt/Are GP contact lenses comfortable?
For someone who has never worn a GP lens before, there will be initial lens awareness that will go away after about two to three weeks of wear (on average). Your eyelids gradually adapt so that you don't feel the lens with each blink. Once over that initial hurdle, the comfort of soft and GP contacts are comparable. I like to compare getting your first GP lenses to getting a new pair of shoes. You may initially feel the shoes, but once you break into them and they are properly fitted, that feeling disappears.
If you are interested in gas-permeable contact lenses, request an appointment for a consultation here: