By: Dr. Liz
I have been working closely with a patient of mine who has had bilateral corneal transplants due to severe kerataconus. I found a specialized contact lens that is both hard and soft all in one lens. I will be learning how to use this lens next week. It is a relatively complicated lens to fit but I am looking forward to the challenge!! I will blog about my experience once I complete the fitting course.
Here is a great article I found about Keratoconus. It describes what the disease is, signs and symptoms and some of the latest treatment options.
Thanks to All About Vision for this article.
By Gretchyn Bailey and Judith Lee;
additional contributions and review by Gary Heiting, OD
Often appearing in the teens or early twenties, keratoconus is a progressive eye disease in which the normally round cornea
thins and begins to bulge into a cone-like shape. This cone shape
deflects light as it enters the eye on its way to the light-sensitive retina, causing distorted vision. Keratoconus can occur in one or both eyes.
Keratoconus Symptoms and Signs
Keratoconus can be difficult to detect, because it usually develops
so slowly. However, in some cases, it may proceed rapidly. As the
cornea becomes more irregular in shape, it causes progressive nearsightedness and irregular astigmatism
to develop, creating additional problems with distorted and blurred
vision. Glare and light sensitivity also may be noticed. Keratoconic
patients often have prescription changes every time they visit their eye care practitioner.
It's not unusual to have a delayed diagnosis of keratoconus, if the
practitioner is not familiar with the early-stage symptoms of the
disease.
What Causes Keratoconus?
New research suggests the weakening of the corneal tissue that leads
to keratoconus may be due to 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 weaken and bulge
forward.
Risk factors for oxidative damage and weakening of the cornea
include a genetic predisposition, explaining why keratoconus often
affects more than one member of the same family. Keratoconus is also
associated with overexposure to ultraviolet rays from the sun,
excessive eye rubbing, a history of poorly fit contact lenses and
chronic eye irritation.
Keratoconus Treatment
In the mildest form of keratoconus, eyeglasses or soft contact lenses
may help. But as the disease progresses and the cornea thins and
becomes increasingly more irregular in shape, glasses or soft contacts
no longer provide adequate vision correction.
Treatments for moderate and advanced keratoconus include:
Gas permeable contact lenses: If eyeglasses or soft contact lenses cannot control keratoconus, then rigid gas permeable (RGP) contact lenses
are usually the preferred treatment. Their rigid lens material enables
RGP lenses to vault over the cornea, replacing the cornea's irregular
shape with a smooth, uniform refracting surface to improve vision.
But RGP contact lenses
can be less comfortable to wear than a soft lens. Also, fitting contact
lenses on a keratoconic cornea is challenging and time-consuming. You
can expect frequent return visits to fine-tune the fit and the
prescription, especially if the keratoconus continues to progress.
"Piggybacking" contact lenses: Because fitting a gas
permeable contact lens over a cone-shaped cornea can sometimes be
uncomfortable for the individual with keratoconus, some eye care
practitioners advocate "piggybacking" two different types of contact
lenses on the same eye. For keratoconus, this method involves placing a
soft contact lens, such as one made of silicone hydrogel,
over the eye and then fitting a GP lens over the soft lens. This
approach increases wearer comfort because the soft lens acts like a
cushioning pad under the rigid GP lens.
Normal
eye vs. eye with small amount of keratoconus. The keratoconic cornea
bulges slightly, for a more cone-shaped surface. (Artist's re-creation
of keratometry images.)
Your eye care practitioner will monitor closely the fitting of
"piggyback" contact lenses to make sure enough oxygen reaches the
surface of your eye, which can be a problem when two lenses are worn on
the same eye. However, most modern contacts — both GP and soft —
typically have adequate oxygen permeability for a safe "piggyback" fit.
Hybrid contact lenses: Hybrid contact lenses have a
relatively new design that combines a highly oxygen-permeable rigid
center with a soft peripheral "skirt." Manufacturers of these lenses
claim hybrid contacts provide the crisp optics of a GP lens and wearing
comfort that rivals that of soft contact lenses. Hybrid lenses are also
available in a wide variety of parameters to provide a fit that
conforms well to the irregular shape of a keratoconic eye.
Intacs: (Addition Technology, Des Plaines, Ill.) Intacs or corneal inserts received FDA
approval for treating keratoconus in August 2004. These tiny plastic
inserts are placed just under the eye's surface in the periphery of the
cornea and help re-shape the cornea for clearer vision. Intacs may be
needed when keratoconus patients no longer can obtain functional vision
with contact lenses or eyeglasses.
Several studies show that Intacs can improve the best
spectacle-corrected visual acuity (BSCVA) of a keratoconic eye by an
average of two lines on a standard eye chart.
The implants also have the advantage of being removable and
exchangeable. The surgical procedure takes only about 10 minutes.
Intacs might delay but can't prevent a corneal transplant if
keratoconus continues to progress.
Boston Scleral Lens Prosthetic Device (BSLPD): This
cone-shaped device resembles a large contact lens and works partly by
maintaining a "pool" of fluid on the eye's surface through which light
rays pass and are bent to achieve proper focus. Rather than resting on
the eye's clear surface or cornea, however, the lens makes contact with
the "white" or sclera of the eye. The device was FDA-approved in 1994.
The BSLPD is both comfortable and able to "fill in" a highly
irregular eye surface with fluid to help achieve proper focus. If other
methods of keratoconus correction such as RGP contact lenses don't
work, the BSLPD with its unique characteristics may be an option. To
qualify for the BSLPD, you must have a severe, unusual or otherwise
untreatable condition.
In cases of financial need, the non-profit Boston Foundation for
Sight providing the lens will help subsidize or pay outright the $7,600
needed for lenses and fittings for both eyes. The price of a lens and
fitting for one eye is $5,000. The BSLPD also has demonstrated
effectiveness as a treatment for severe dry eye.
C3-R: (Boxer Wachler Vision, Los Angeles) Another new
procedure for treating keratoconus, known by the brand name of C3-R
(corneal collagen cross-linking with riboflavin), is a non-invasive
method of strengthening corneal tissue to halt bulging of the eye's
surface.
In the C3-R procedure, eye drops containing riboflavin (vitamin B2)
are placed on the cornea and are then activated by ultraviolet (UV)
light to strengthen links between the connective tissue (collagen) fibers within the cornea.
In the United States, FDA clinical trials for corneal collagen cross-linking began in early 2008.
Early results showing benefits of using this method have been
promising. In 2008, University of Siena researchers in Italy reported
positive outcomes in all 44 eyes that were followed for three years
after treatment with corneal collagen cross-linking.*
Other researchers have concluded that this simple treatment method
might reduce significantly the need for corneal transplants among
keratoconus patients. Corneal cross-linking also is being investigated
as a way to treat or prevent keratoconus-like complications following LASIK or other vision correction surgery.
Corneal transplant: Some people with keratoconus can't
tolerate a rigid contact lens, or they reach the point where contact
lenses or other therapies no longer provide acceptable vision. The last
remedy to be considered may be a cornea transplant, also called a penetrating keratoplasty (PK or PKP). Even after a transplant, you most likely will need glasses or contact lenses for clear vision. 
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