Keratoconus is a progressive eye disease where the typically round cornea thins and begins to bulge into a cone-like shape. This cone shape deflects light as it gets in the eye on its way to the light-sensitive retina, triggering distorted vision.
Keratoconus can happen in one or both eyes and often begins during an individual’s teens or early 20s.
Keratoconus Symptoms and Signs
As the cornea ends up being more irregular in shape, it causes progressive nearsightedness and irregular astigmatism to develop, creating extra problems with distorted and blurred vision. Glare and light sensitivity also might take place.
Often, keratoconic patients experience changes in their eyeglass prescription whenever they visit their eye care practitioner.
What Causes Keratoconus?
New research recommends the weakening of the corneal tissue that results in keratoconus might be due to an imbalance of enzymes within the cornea. This imbalance makes the cornea more prone to oxidative damage from substances called totally free radicals, triggering it to compromise and bulge forward.
Risk factors for oxidative damage and weakening of the cornea consist of a genetic predisposition, describing why keratoconus typically affects more than one member of the very same family.
Keratoconus also is associated with overexposure to ultraviolet rays from the sun, excessive eye rubbing, a history of poorly fitted contact lenses and chronic eye inflammation.
See also: Complete List of Eye Diseases
In the mildest form of keratoconus, glasses or soft contact lenses might assist. However as the disease advances and the cornea thins and becomes increasingly more irregular fit, glasses and routine soft contact lens creates not provide sufficient vision correction.
Treatments for progressive keratoconus include:
- Corneal cross-linking (CXL)
- Custom-made soft contact lenses
- Gas permeable contact lenses
- “Piggybacking” contact lenses
- Hybrid contact lenses
- Scleral and semi-scleral lenses
- Topography-guided conductive keratoplasty
- Corneal transplant
Corneal crosslinking. This procedure, also called corneal collagen cross-linking or CXL, reinforces corneal tissue to halt bulging of the eye’s surface area in keratoconus.
There are two variations of corneal crosslinking: epithelium-off and epithelium-on.
With epithelium-off crosslinking, the outer layer of the cornea (called the epithelium) is removed to enable entry of riboflavin, a type of B vitamin, into the cornea, which then is activated with UV light.
With the epithelium-on approach (likewise called transepithelial crosslinking), the corneal epithelium is left undamaged during the treatment. The epithelium-on approach needs more time for the riboflavin to permeate into the cornea, but potential benefits consist of less risk of infection, less pain and faster visual recovery, inning accordance with supporters of this method.
And Dr. Brian Boxer Wachler, who started performing and developing transepithelial crosslinking in 2003, has actually reported outstanding outcomes with keratoconus patients such as bobsledder Steve Holcomb, whose enhanced vision helped his group win a gold medal in the 2010 Winter Olympics.
Dr. Boxer Wachler, who is a member of the All About Vision editorial advisory board, refers to the procedure as the Holcomb C3-R, which is the first instance of a medical procedure being named for an Olympic athlete.
In April 2016, the FDA gave approval of Avedro’s KXL System corneal collagen cross-linking treatment of progressive keratoconus. The approval consists of use of the pharmaceutical and medical device company’s Photrexa and Photrexa Viscous riboflavin options with the KXL System during the procedure.
Avedro’s Photrexa/KXL System is the first corneal collagen cross-linking system to gain the required regulative approval to be carried out by eye doctors in the United States for this sight-threatening condition. More than 200,000 patient eyes have been treated with the system outside the United States prior to FDA approval, inning accordance with the company.
Corneal crosslinking may lower considerably the need for corneal transplants among keratoconus patients. It also is being examined as a way to treat or prevent complications following LASIK or other vision correction surgery.
Utilizing a mix of corneal crosslinking and Intacs implants (see above) likewise has shown appealing outcomes for dealing with keratoconus.
In a research study released in early 2012, progressive mild to moderate keratoconus was securely and successfully treated with a mix of corneal crosslinking and implantation of a toric phakic IOL.
Customized soft contact lenses. Recently, contact lens producers have presented custom-made soft contact lenses specially created to remedy mild-to-moderate keratoconus. These lenses are made-to-order based on detailed measurements of the individual’s keratoconic eye( s) and may be more comfortable than gas permeable lenses (GPs) or hybrid contact lenses for some users.
In the United States, customized soft contacts that are readily available for the correction of keratoconus include:
- KeraSoft lenses (Bausch + Lomb). These high-water silicone hydrogel lenses can correct approximately 20 diopters (D) of nearsightedness or farsightedness and approximately -12 D of astigmatism.
- NovaKone lenses (Alden Optical). These medium-water hydrogel lenses can remedy up to 30 D of nearsightedness or farsightedness and as much as -10 D of astigmatism.
Both lenses have a really wide range of fitting parameters for a tailored fit and are larger in diameter than routine soft lenses for higher stability on a keratoconic eye.
In a current study of the visual performance of toric soft contacts and stiff gas permeable lenses for the correction of moderate keratoconus, though GP lenses offered better visual skill in low-contrast scenarios, soft toric lenses carried out similarly well in high-contrast acuity screening.
Customized soft toric lenses likewise can be a great alternative for part-time wear for individuals with keratoconus who can not tolerate using gas permeable lenses full-time. For instance, the GP lenses might be worn during work and for driving, and the soft lenses might be worn during leisure activities after work or for a short break from the GP lenses throughout the day.
Custom-made toric soft contacts for keratoconus are substantially more expensive than routine soft contacts, but vision insurance coverage might cover a few of the expenses connected with contact lenses for keratoconus.
Gas permeable contact lenses. If glasses or soft contact lenses can not control keratoconus, then gas permeable contact lenses usually are the favored treatment. Their rigid lens product enables GP lenses to rise over the cornea, changing its irregular shape with a smooth, consistent refracting surface to improve vision.
But GP contact lenses can be less comfy to wear than soft contacts.
Also, fitting contact lenses on a keratoconic cornea is tough and lengthy. You can expect frequent return visits to your eye care provider so she or he can fine-tune the fit and your prescription, especially if your keratoconus continues to advance.
Also read: LASIK Risks And Complications
“Piggybacking” contact lenses. Due to the fact that fitting a gas permeable contact lens over a cone-shaped cornea can often be unpleasant for an individual with keratoconus, some eye care practitioners promote “piggybacking” two various types of contact lenses on the exact same eye.
For keratoconus, this technique involves placing a soft contact lens, such as one made from silicone hydrogel, over the eye then fitting a GP lens over the soft lens. This method increases wearer comfort due to the fact that the soft lens acts like a cushioning pad under the rigid GP lens.
Your eye care practitioner will keep an eye on closely the fitting of “piggyback” contact lenses to make sure adequate oxygen reaches the surface of your eye, which can be a problem when two lenses are endured the exact same eye. However, most modern contacts — both GP and soft — generally have adequate oxygen permeability for a safe “piggyback” fit.
Hybrid contact lenses. The UltraHealth and ClearKone hybrid contact lenses made by SynergEyes combine an extremely oxygen-permeable stiff center with a soft peripheral “skirt.” These lenses were developed specifically for keratoconus, and the central GP zone of the lens vaults over the cone-shaped cornea for increased convenience.
Hybrid contact lenses supply the crisp optics of a gas permeable contact lens and using convenience that matches that of soft lenses, inning accordance with SynergEyes. UltraHealth uses silicone hydrogel material for the soft lens skirt, offering higher oxygen transmissibility than ClearKone’s hydrogel skirt.
UltraHealth and ClearKone are available in a wide variety of parameters to offer a fit that adheres well to the irregular shape of a keratoconic eye.
Scleral and semi-scleral lenses. These are large-diameter gas permeable contacts — large enough that the periphery and edge of the lens rest on the “white” of the eye (sclera). Scleral lenses cover a larger portion of the sclera, whereas semi-scleral lenses cover a smaller area.
Since the center of scleral and semi-scleral lenses vaults over the irregularly shaped cornea, these lenses don’t apply pressure to the eye’s cone-shaped surface area for a more comfortable fit. These larger lenses also are more stable than standard gas permeable contact lenses, which move with each blink since they cover just a portion of the cornea.
One example of a scleral lens is the Boston Scleral Lens Prosthetic Device (BSLPD). In addition to correcting vision problems associated with keratoconus, this device is used to treat severe dry eyes that might be brought on by Sjogren’s syndrome and other systemic illness and to manage complications connected with a corneal transplant.
To get approved for the BSLPD, you should have a severe, uncommon or otherwise untreatable condition.
In cases of financial requirement, the non-profit Boston Foundation for Sight, which developed the BSLPD, might help fund the cost of the fitting and lens, which typically runs a number of thousand dollars.
Intacs. These surgically applied corneal inserts produced by Addition Technology got FDA approval for dealing with keratoconus in August 2004. The small plastic inserts are placed just under the eye’s surface area in the periphery of the cornea and help re-shape the cornea for clearer vision.
Intacs may be required when keratoconus patients not can get practical vision with contact lenses or spectacles.
Numerous research studies show that Intacs can improve the best spectacle-corrected visual acuity (BSCVA) of a keratoconic eye by approximately two lines on a standard eye chart. The implants likewise have the advantage of being removable and exchangeable. The surgical procedure takes just about 10 minutes.
Intacs might delay however cannot prevent a corneal transplant if keratoconus continues to progress.
See also: Bump on Eyeball (Pinguecula)
Topography-guided conductive keratoplasty. While more research study is required, early results of a small study involving topography-guided conductive keratoplasty (CK) reveal this procedure might help smooth irregularities in the corneal surface.
This treatment uses energy from radio waves, used with a small probe at numerous points in the periphery of the cornea to reshape the eye’s front surface. A topographic “map” produced by computer system imaging of the eye’s surface area assists create personalized treatment strategies.
In October 2010, the American Journal of Ophthalmology reported that 15 of 21 keratoconic eyes treated with topography-guided CK attained more normal corneal proportion.
Corneal transplant. Some individuals with keratoconus cannot endure a stiff contact lens, or they reach the point where contact lenses or other therapies not supply acceptable vision.
The last solution to be thought about might be a cornea transplant, also called a permeating keratoplasty (PK or PKP). After a transplant, you probably will require glasses or contact lenses for clear vision.