Keratoconus is a progressive eye condition that affects the cornea, the transparent layer at the front of the eye. In people with keratoconus, the cornea progressively loses its normal curved shape, and instead develops into a cone-like bulge. Over time, this can prevent the eye from focusing properly, causing blurred, distorted vision.1
Contact lenses can play an important role in treating keratoconus because they can help to mask the shape of the cornea. Here, we’ll take a closer look at the different contact lens options for keratoconus your doctor may consider when examining you.
What causes keratoconus?
There are a number of factors that researchers believe cause keratoconus. Research suggests that keratoconus may develop because of an imbalance of enzymes within the cornea. This imbalance makes the cornea more susceptible to oxidative damage from compounds called free radicals, causing it to become weaker and bulge. Genetics also play a large role in keratoconus development, as 10% of people with the condition will have a parent who also experiences it.1 Keratoconus is also associated with prolonged exposure to UV rays from the sun, excessive eye rubbing, and chronic eye irritation.
Although keratoconus is typically diagnosed within the late teens to the early 20s, symptoms may not be experienced until the condition progresses over the next few decades.1 Symptoms of keratoconus can change over time and may even differ between eyes.
Early symptoms include mild blurred vision, a slight distortion of vision (straight lines appear wavy), redness and swelling of the eyes, and photophobia (increased sensitivity to light and glare).1 As the cornea continues to change shape, many people develop vision conditions such as astigmatism or myopia (shortsightedness), which can cause blurry vision to worsen. For some, wearing contact lenses with an old prescription may no longer be comfortable because they do not fit the new shape of the eye.
Why are contact lenses used for vision correction in those with keratoconus?
A common way to correct vision problems in people with keratoconus is through the use of contact lenses. While prescription glasses can be effective for milder cases of keratoconus, you may need to switch to contact lenses to correct your vision as the condition progresses.1 Here are a few contact lens options to your doctor may consider:
Rigid Gas Permeable Contact Lenses
Rigid Gas Permeable (RGP) contacts are often the first option for keratoconus. They are made of a rigid, breathable plastic that creates a tear layer that makes the shape of the cornea, correcting it to fit the natural shape of the lens. These contact lenses are easy to put in and out, and are relatively easy to look after. While contact lens wear increases the risk of an eye infection, with RGP lenses the risk is less. RGP lenses can be a little uncomfortable initially — especially for first-time contact lens wearers. If you find it too uncomfortable to wear RGP lenses for large amounts of time or if your keratoconus has worsened and RGPs no longer improve your sight, you might be offered another type.2
Scleral Contact Lenses
A scleral lens is a large, made-to-measure lens that sits on the sclera (the white of your eye), rather than on your cornea. As your sclera is less sensitive than your cornea, these lenses can be more comfortable for people with keratoconus compared to RGPs.2
Piggyback Contact Lenses
Piggybacking involves wearing a pair of soft contact lens underneath an RGP lens to act as a cushion. Although this involves more care and work, it can help to prevent the rigid lens from irritating the corneal surface and ease contact lens discomfort.
How can custom soft contact lenses help correct keratoconus ?
Custom soft contact lenses can be used for those with mild-to-moderate keratoconus Iin people who are unable to tolerate harder contact lens options. These contact lenses are made-to-order to ensure that they fit perfectly the wearer’s eye. They are specially designed to fit over the central steep part of the bulging cornea, and have a variable lens thickness to neutralize the irregularity of the cornea. Since they are made-to-measure, keratoconus patients typically consider custom soft lenses to be the most comfortable contact lens option. 3 Although they are not the typical choice for keratoconus patients, custom soft contact lenses can provide a good balance between comfort and vision correction.
If you do have keratoconus, then your first step should be to see a doctor. They’ll be able to help you find the right lens for you. In the meantime, if you’re interested in learning more about eyecare and contact lenses, head over to our contact lens resource for more information.
- American Academy of Ophthalmology. (no date). Keratoconus. [Online]. Available at: https://www.aao.org/eye-health/diseases/what-is-keratoconus [Accessed 5 November 2019].
- Rathi VM, Mandathara PS, Taneja M, Dumpati S, Sangwan VS. Scleral lens for keratoconus: technology update. Clin Ophthalmol. 2015;9:2013–2018. Published 2015 Oct 28. [Online]. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4630203/ [Accessed 5 November 2019].
- Rathi VM, Mandathara PS, Dumpati S. Contact lens in keratoconus. Symposium: Keratoconus. 2013; Volume 61; Issue 8; Page 410-415. [Online]. Available at: http://www.ijo.in/article.asp?issn=0301-4738;year=2013;volume=61;issue=8;spage=410;epage=415;aulast=Rathi [Accessed 5 November 2019].