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Why Are Hard Contact Lenses Still Used?

2026.10.13
Why Are Hard Contact Lenses Still Used?

Say "contact lenses" today and most people picture soft, flexible lenses. With daily disposables everywhere, rigid lenses can feel like something from the past.

But hard lenses have not disappeared. Today's hard lenses are RGP (rigid gas permeable) lenses made of materials that let oxygen through, and for some eyes they do what soft lenses cannot.

How hard lenses came to be the size they are today is covered in How a Lens That Covered the Whole Eye Shrank to the Size of an Iris.

When being rigid becomes an advantage

A rigid lens and a larger soft lens side by side

Soft lenses are flexible, so they follow the shape of the cornea. If the cornea is even, that is no problem.

But if the cornea itself is uneven, things change. A soft lens follows that shape, while a rigid lens keeps its own shape. That is why it can create a new smooth surface in front of an irregular cornea.

An eye with keratoconus

An optometrist looking at a corneal topography map

A typical example is keratoconus. The American Academy of Ophthalmology (AAO) describes keratoconus as the cornea thinning out and bulging forward like a cone.

  • It often starts in the late teens to early 20s.
  • Vision symptoms slowly get worse over about 10 to 20 years.
  • Early on there may be blurred vision, straight lines that look wavy, glare and redness.
  • As it progresses, nearsightedness or astigmatism keeps increasing so the prescription must change often, and lenses can become hard to wear.

The AAO explains that early on glasses or soft lenses can correct vision, but as it progresses, hard lenses may be needed. It also stresses not rubbing your eyes, because rubbing damages the weakened corneal tissue and can make symptoms worse.

Hard lenses are a way of correcting vision, not a treatment that stops keratoconus from progressing. One treatment aimed at stopping progression is corneal cross-linking, which uses ultraviolet light and riboflavin eye drops. The AAO explains that, unlike hard lenses that only improved refractive status, this treatment was developed with the aim of actually halting the progression of keratoconus. Severe cases may need a corneal transplant.

A lens that rests on the white of the eye: scleral lenses

An ordinary hard lens sits on the clear dome of the eye (the cornea). But there is a much larger kind of hard lens: the scleral lens.

Cleveland Clinic in the US describes scleral lenses as follows.

  • They are large lenses that extend past the cornea and cover part of the white of the eye (the sclera).
  • The center of the lens vaults over the cornea like an arch and does not touch it.
  • The small space between the cornea and the lens is filled with saline or another liquid that covers the cornea.
  • To put one in, you fill the lens with saline first and then bring it up to the eye.

The AAO's journal EyeNet explains that this space acts as a fluid reservoir that continuously bathes the cornea. It also says scleral lenses are more comfortable than hard lenses resting on the cornea, because the conjunctival tissue they rest on is less sensitive than the cornea.

Cleveland Clinic explains that scleral lenses are used for corneal diseases such as keratoconus, severe dry eye, corneal scarring from injuries, and severe refractive errors.

How do hard and scleral lenses compare?

In 2024, a research team in Paris, France, had 14 patients with keratoconus (25 eyes) wear both kinds of lens and compared them.

  • Corrected visual acuity showed no significant difference between hard and scleral lenses.
  • With both lenses, vision was clearly better than with glasses.
  • Higher-order aberrations, which blur vision, were lower with scleral lenses.

Which lens suits you depends on the state of your cornea, comfort and cost. EyeNet says that in the US a scleral lens costs roughly $1,000 to $5,000 per eye.

Are hard lenses used without keratoconus?

The American Optometric Association (AOA) lists the pros and cons of RGP lenses as follows.

Pros

  • Excellent vision
  • Short adaptation period
  • Correct most vision problems
  • Easy to put on and care for
  • Relatively long life
  • Also available for myopia control and corneal refractive therapy (ortho-k)

Cons

  • Require consistent wear to maintain adaptation
  • Can slip off the center of the eye more easily than other types
  • Debris can sometimes get under the lens
  • Require regular follow-up visits

Ortho-k lenses are also a kind of hard lens. They are covered in What Do Ortho-K Lenses Do to Your Eyes While You Sleep?

In short

  • Soft lenses follow the shape of the cornea; hard lenses keep their own shape.
  • That is why eyes with an uneven cornea, as in keratoconus, may need hard or scleral lenses.
  • Hard lenses are a form of correction; the progression of keratoconus needs separate medical care.
  • If your prescription changes often or straight lines look bent, have your cornea examined by an eye doctor.

References

This article is general information and does not replace diagnosis or treatment. Follow the examination and instructions of an eye care professional for lens choice and treatment of corneal disease.

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