The National Eye Institute (NEI) estimates that 1 in 2000 people are affected by keratoconus, the leading form of corneal dystrophy. Some studies have reported the number may be as high as 1 in 500, depending on the criteria used, as high astigmatism is often confused for keratoconus and vice versa. With these figures in mind, it seems strange that you may have never heard about this disorder until you or a loved one were diagnosed. Part of this is due to the high success of the available treatment options and management strategies. By understanding this disorder, how it may affect you, the treatments available and the support systems available to assist those with keratoconus, you can be proactive and educated regarding your choices. This empowerment is integral to a successful management strategy or treatment plan, as patient motivation always factors heavily into success rates.
The Anatomy of Keratoconus
The cornea is the crystal-clear, rounded section on the front of your eye, in front of the black pupil in the center and the colored ring of iris around it. In typical eyes, you can see the smooth, gentle, uniform curve of the cornea if you look at a person’s profile in good lighting. With keratoconus, however, that gentle curve is not correct. In an eye afflicted with keratoconus, the cornea is thin and damaged. In extreme cases, the cornea will appear almost conical or nipple-shaped. Less-severe cases aren’t always visible to the naked eye, but the problem remains the same. Keratoconus is, in essence, a misshapen cornea that distorts vision, creates halos around lights and poor night vision. The condition usually worsens throughout the patient's teens and twenties, then stabilizes or slowly progresses, in their thirties. It is possible, however, for keratoconus to be diagnosed in older adults.
Speculation Regarding the Origins of Keratoconus
We do not yet understand what causes keratoconus. We do, however, have many theories that may one day bear fruit in finding a true cure. Promising research being done lately has pointed to detrimental enzyme activity in the cornea called proteases. Other studies supposition that free radicals build up in the corneal tissue, which causes oxidation. Whatever the cause, there is strong evidence that the risks of developing keratoconus are largely genetic. The disorder is noted most in certain ethnic groups, notable South Asians. Those diagnosed with Down Syndrome, Marfan Syndrome, Alport Syndrome are at higher risk. Even less-serious diagnoses such as asthma, eczema and allergies have a higher instance of keratoconus. It’s been suggested that the eye rubbing associated with some of these problems may play a factor in keratoconus development, so eye rubbing has been heavily discouraged by allergists, optometrists and the medical community as a whole.
Symptoms and Early Warning Signs
Keratoconus usually presents in teens and young adults who seek out an optometrist, believing they need standard vision correction. Rarely, keratoconus will present earlier or later in life. The chief complaints are usually a slight blurring of vision and a ‘ghosting’ image around lights. It’s common for this to prompt a visit soon after a young person begins to learn to drive, as night vision is affected in the earliest stages of keratoconus. In some cases, eye pain, eye strain, photophobia and itching may also be complaints. Of course, many of these problems can be attributed to other eye issues such as allergies, making a prompt examination necessary for proper diagnosis.
Keratoconus Treatment Options
The treatment options for keratoconus are varied and depend on the severity of the disorder. Keratoconus has four stages, determined chiefly by corneal thickness and level of refractive error. Your eye care professional will be able to explain your options to you and explain which would likely provide the best possible outcome.
Contact lenses are usually the first choice of treatment, especially in the earlier stages. Lens wear options are varied and, again, the treatment choice entirely depends on the individual’s case, condition, ability to tolerate lenses and other factors determined by your optometrist or ophthalmologist.
- Rigid gas-permeable (RGP) lenses, also called hard lenses, were once the go-to choice to help form a normal curvature and restore clear, crisp vision. For those who tolerate them well, they’re still a valid, great choice. They are made of a nearly rigid plastic and trap the tear film between the lens and the cornea. Once smoothed and rounded properly, the cornea allows light into the eye without distortion, improving visual acuity.
- Hybrid contact lenses are newer technology that can assist keratoconus patients who don’t tolerate RGP lenses very well. Hybrid lenses have a rigid center that forms the properly corneal shape. This rigid center is surrounded by a soft ‘skirt’ of sorts that surrounds that center. Not only can hybrid lenses be easier to handle and insert, some patients find them more comfortable and tolerable than a traditional RGP lens.
- Scleral lenses are another great option for keratoconus patients. They are larger and cover a bigger section of the eye. Not only does this offer a larger surface area for handling and insertion, it gives more stability to the lens and allows a smooth, functional corneal shape to be created.
- Finally, piggyback lenses offer the opportunity to wear a soft lens against the eye for comfort and vision correction and an RGP lens on top of the soft lens in a special sunken area created for it for more visual correction and reshaping of the cornea.
With all types of contact lens treatments, your patience is absolutely critical to the eventual success of the fitting. Not everyone handles contact lenses well. Learning to insert and remove them requires dexterity and determination for some people, and wearing them can be uncomfortable as your eyes adjust. Don’t be surprised if it takes some trial and error to find the perfect lens or lens combination to suit you and your diagnosis adequately.
Eye surgery may sound like a scary proposition, but it’s sometimes the best choice to create a stable, smooth corneal surface and restoring visual acuity. Of course, your ophthalmologist will discuss surgical options with you in great detail before you’re asked to make such a big decision. Careful consideration and study are both normal reactions to being told surgery is your best option, so don’t be afraid to ask questions and request further information about your surgical possibilities.
A corneal transplant is one of the most common surgical answers to late-stage keratoconus. Using a cornea from a donor, the diseased cornea is removed and replaced with healthy tissue. This is extremely useful for patients who have trouble with their contact lenses or have damaged corneas from long-time contact lens use. As the cornea does not have a blood supply, there’s no concern over blood or tissue types and rejection isn’t usually an issue. In the rare case where a transplant fails, a repeat transplant is often successful.
Corneal ring implants use flexible implants to pull the cornea into a more ideal shape. This is an ideal procedure for those with lots of corneal tissue that is simply misshapen, and it’s a method favored for young patients because the results can be changed by repositioning the implants, if needed. It’s also fully reversible, making it one of the most conservative surgical options available.
Corneal collagen cross-linking was recently approved for use in the United States, although its use with keratoconus is still in its testing stages. This procedure encourages the growth of the body’s natural collagen fibers, which strengthen the cornea and improve its shape dramatically. Should this turn out to be a viable treatment, keratoconus patients may be able to see an effective ‘cure’ without relying on donor tissue or implants.
In rare cases, a radial keratotomy can be performed to increase visual acuity and strengthen the cornea. A radial keratotomy uses a spoke-like pattern of incisions to draw the cornea into a proper curve with the creation of scar tissue. For most keratoconus patients, however, this is not a good choice, as it can weaken an already-compromised cornea.
Available Support Systems
If you are having trouble living with low vision or need help finding resources, talk to your optometrist or ophthalmologist about your issue. There are visual therapists available to help train you to use what vision you do have effectively, as well as programs designed to find adaptive technology that suits your needs. If you feel you’re becoming depressed or anxious due to your condition, get a referral for a psychologist who is experienced in helping those with diminished sight.
The UK Keratoconus Self Help and Support Association has discussion groups, newsletters, members stories and a wealth of information about Keratoconus.
Author: John Dreyer Optometrist Bsc(Hons), MCOPTOM, DipCLP
Created: 24 Apr 2015, Last modified: 17 Jul 2019