November 10: World Keratoconus Day
November 10 is the first World Keratoconus Day. This is our chance to raise awareness and hope. Let’s join together to recognize World Keratoconus Day and to create awareness.
World Keratoconus Day is an awareness day sponsored by the National Keratoconus Foundation, an educational program of the Gavin Herbert Eye Institute, UC Irvine. NKCF has created a special website for the World KC Day. make sure to visit worldkcday.com to add yourself to their KC map, share your KC selfies, and learn about their other programs and activities.
Keratoconus is a progressive disease, often appearing in the teens or early twenties, in which the cornea thins and changes shape. The cornea is normally a round or spherical shape, but with keratoconus the cornea bulges, distorts and assumes more of a cone shape. This affects the way light enters the eye and hits the light-sensitive retina, causing distorted vision. Keratoconus can occur in one or both eyes.
Kerotoconus Symtoms and Signs
Keratoconus can be difficult to detect, because it comes on slowly. You may have distorted and blurred vision. You might also notice glare and light sensitivity. Keratoconic patients often have prescription changes each time they visit their optometrist. 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?
Causes of keratoconus are unclear. A genetic link may exist, as you may find several keratoconics within an extended family.
In the mildest form of keratoconus, spectacles or soft contact lenses may help. But as the disease progresses and the cornea thins and changes shape even more, spectacles or soft contacts will no longer correct your vision. Rigid gas permeable contact lenses are the next correction method of choice.
The firmer material of a rigid contact lens holds the cornea in place better than a soft contact lens. Fitting contact lenses on a keratoconic cornea is delicate and time-consuming. You can expect frequent return visits to fine-tune the fit and the prescription. The process will begin again when the cornea thins and distorts even more, altering the contact lens fit and prescription needed for clear, comfortable vision.
Information for the Patient with Keratoconus
Keratoconus is defined as a permanent degenerative disease of the cornea in which the central area becomes distorted and cone-shaped due to a thinning and stretching of the tissue. While keratoconus is usually considered to be a “solitary ocular abnormality in an otherwise normal individual”, many keratoconus patients have atopic conditions (allergies). The relationship between allergies and keratoconus is not fully understood. Keratoconus is only rarely associated with other ocular or systemic conditions. Unlike other eye diseases, keratoconus always results in a distortion of vision which eyeglasses are unable to correct. The only non-surgical therapy to provide effective vision is the wearing of therapeutic lenses for keratoconus. If the therapeutic lenses cannot be worn, the only alternative is corneal transplant surgery. The condition is relatively rare. The prevalence in the general population is reported to vary between 0.02% (1 in 5,000) to 0.6% (6 in 1,000).
Keratoconus is an unusual disease in that only a portion of the eye, the cornea, is involved. There is no severe pain associated with the disease (unless unusual secondary complications develop). There is no active inflammation present, and thus, the eye does not redden or appear more irritated than eyes without keratoconus; however, there may be general discomfort associated with keratoconus due to either drying of the eye resulting from altered blinking, or allergic changes of the lid and palpebral conjunctive (the lining of the lid in contact with the eye). The eye may exhibit an unusual light reflex or teary appearance if the keratoconus is advanced.
Keratoconus involves a change in the tissue of the cornea. The cornea can be thought of as a clear transparent watch crystal which forms the front surface of the eye, providing over 75% of the total focusing power for the eye. The cornea usually presents a spherical surface – that is, the surface is perfectly round as is the surface of a billiard ball. If the surface is not perfectly round, but more curved in one direction than in the other, the cornea is referred to as toric or astigmatic. The corneal surface in this instance may be compared to that of an egg. Keratoconus differs from all other eye diseases in that tissue changes and thinning of the cornea result in a conical corneal shape (resembling a missile or a bullet). This conical shape results in light scatter and visual interference.
The Etiology of keratoconus is unknown. Recent studies with the electron microscope have demonstrated that fundamental changes exist in the cornea of the keratoconus patient. Collagen is present in the cornea and provides the basis support for the corneal shape. The collagen for patients with keratoconus is different from the collagen for patients without keratoconus. It is believed that the collagen difference and possible other differences in the stroma and/or epithelium account for keratoconus. There appears to be a genetic factor with certain people, but the total role of genetics has not yet been completely established.
Classification of Keratoconus & Visual Results
Keratoconus is highly individual in characteristics and severity. When discussing the visual performance possible with either eyeglasses or therapeutic lenses for keratoconus, the severity of the keratoconus must first be established. The following classification describes the stages and progression of keratoconus and the resulting visual performance.
1. Incipient Keratoconus Incipient keratoconus is the earliest stage of the disease. Diagnosis at this stage may be difficult and may require specialised equipment and evaluation by an ophthalmologist or an optometrist with significant experience with keratoconus patients. The quality of the vision with eyeglasses is usually adequate, although it is not as clear as prior to the development of keratoconus. Frequent prescription changes, particularly if astigmatic, may indicate that keratoconus is developing or progressing.
2. Mild Keratoconus With mild keratoconus, eyeglasses cannot provide optimal vision because the cornea has become conically deformed so that light is scattered. The patient with this condition may read the eye test chart with eyeglasses well enough to pass the driver’s test (20/40 acuity), but still may not be able to drive adequately due to distorted vision and shadows. A further complication is multiple halos and images which may surround lights sources, thereby resulting in compromised vision. Sensitivity to light of all types is also increased. These problems are worse at night. Therapeutic lenses for keratoconus are necessary to provide both clear and normal vision. A rigid therapeutic lens is usually required to provide a spherical surface over the deformed cornea.
3. Moderate Keratoconus Moderate keratoconus is a progression of mild keratoconus. While mild keratoconus can usually be corrected with a therapeutic lens so that there are no significant visual disadvantages, visual compromise may occur with moderate keratoconus, particularly at night. This is caused by the severity of the conical shape which allows rays of light to creep around the edge of the lens. This results in some glare and distortion, particularly at night when the pupil is enlarged.
4. Severe Keratoconus Vision may be significantly compromised. In those cases where it cannot be adequately corrected with therapeutic lenses, keratoplasty (corneal transplant surgery) is required. It is obviously desirable to prevent keratoconus from progressing to the severe stage.
There are 2 methods of treatment for keratoconus:
1. Therapeutic Contact Lenses Therapeutic contact lenses differ from usual contact lenses in both physical characteristics and purpose. There are different types of therapeutic lenses designed and prescribed for the treatment of ocular diseases. Only 1% of all contact lenses, however, are therapeutic lenses, while the remainder are worn for either convenience, appearance, or for certain elective visual advantages. The therapeutic lens for keratoconus is fitted as a physical replacement for the deformed cornea, thereby providing a regular surface and improving vision.
(a) Fitting Procedure
Contact lenses are usually fitted so as to be in even contact with the central areas of the cornea (these are referred to as bearing areas). Keratoconus, however, is a disease in which the central areas of the cornea become thinner and are weakened. Recent research has shown that the usual methods of fitting contact lenses to keratoconus with the favoured technique of central bearing results in a special form of irritation, which usually develops into permanent scarring of the weakened central areas. The time course for this scarring may be rapid, within 1 to 5 years. Scarring of the central cornea clouds vision and as the scarring becomes more severe, it may be impossible to obtain adequate vision with any type of lens, even the most sophisticated therapeutic lens. Cornea transplant surgery is then necessary to remove the scarred cornea and insert a normal donor cornea. This same research has also established that it is possible to avoid this type of scarring by using special therapeutic lenses which shift the bearing areas of the lens away from the weakened central areas of the corner to the less compromised adjacent areas. This type of special therapeutic lens, however, requires intricate and complex fitting procedures. It is necessary to design the lens to accuracies of 1/3,500″ thickness (the thickness of a red blood cell) and to maintain this tolerance as wearing continues. Every eye with keratoconus presents a different shape and require individual evaluation. Since the shape of the cornea is both deformed and conical, fitting procedures are very different from those used with normal eyes. Special evaluation and fitting techniques are required to achieve the best initial custom lens. The reaction of the eye to the initial therapeutic lens and the resulting wearing success will vary with severity and the type of keratoconus and also the individual characteristics of the patient. Thus, the presence of allergic and/or dermatologic conditions may influence both are very important and poor blinking may result in failure. Thus, as lens wearing adaptation proceeds, it is frequently necessary to continue altering and customising the therapeutic lens design or refitting a different type of therapeutic lens in order to achieve the ideal fit. It is generally accepted that with the fitting of standard lenses to keratoconus it is “almost impossible to achieve a successful fit unless modifications are done in the practitioner’s office”. To achieve the tolerances required for these special therapeutic lenses for keratoconus, it is mandatory for the practitioner to maintain more stringent controls than those provided by contact lens manufacturing laboratories. Thus, a laboratory capable of precision tolerances must be available in the practitioner’s office in order to utilise special therapeutic lenses for keratoconus. It is obviously critical to strive for absolute perfection with the design of keratoconus lenses in order to provide the best possibility of avoiding scarring of the cornea, minimising the progression of keratoconus, and achieving long-term success.
(b) Long-Term Success and Follow-up
Modern contact lenses have been used to treat keratoconus since 1938. Our personal experience with keratoconus spans 25 years and we have continued to follow patients for whom fittings were initiated at that time. It has been reported that after a number of years wearing standard contact lenses (5 – 15), keratoconus may progress so that lenses cannot be worn and keratoplasty (corneal transplant surgery) will be necessary. Our research and experience indicates that over 90% of all keratoconus patients can continue to wear lenses after 10 years, provided:
(1) a therapeutic rather than a standard lens is fitted
(2) the therapeutic lens is meticulously customised to the individual patient and
(3) both patient care and professional services are stringently maintained. Long-term success is dependent upon intensive custom fitting procedures during the first year and continuing follow-up with necessary changes and refittings as required. Following the completion of initial fittings, it is mandatory to schedule evaluation for every keratoconus patient at least twice per year. Many keratoconus patients require more frequent attention. The number of required visits will vary with the characteristics of the individual patient. Without this intensive care, there is a greater probability that deterioration and progression of the keratoconus will occur so that keratoplasty (corneal transplant surgery) will then be required.
2. Collagen Cross-linking System
Corneal Collagen Cross-linking with Riboflavin (CXL) is a developing keratoconus treatment. CXL works by increasing collagen cross-links which are the natural ‘anchors’ within the cornea. These anchors are responsible for preventing the cornea from bulging out and becoming steep and irregular. During the corneal cross-linking treatment custom made riboflavin drops saturate the cornea, which is then activated by ultraviolet light. This process has been shown in laboratory and clinical studies, to increase the amount of collagen cross-linking in the cornea and strengthen the cornea. Collagen cross-linking is not a cure for keratoconus. The aim of this treatment is to arrest the progression of keratoconus and thereby prevent further deterioration in vision and the need for corneal transplantation. Collagen cross-linking is therefore best suited for people with progressive keratoconus, before the cornea gets too distorted. This would usually mean treating people when they are in their mid to late teens, as this is typically when the disease commences and when it is progressing most rapidly. Spectacles or contact lenses will still be needed following the cross-linking treatment (although a change in the prescription may be required) but it is hope that it could limit further deterioration of vision and the need for corneal transplantation. This procedure, developed at the Technische Universität Desden, Germany has been shown to slow or arrest the progression of keratoconus in published European studies. Collagen cross-linking is not recommended for patients with a cornea thickness of less than 400 microns. This is to ensure minimal side effects on the corneal cells after the surgery. Patients with prior herpetic infections are also advised against CXL, as the procedure might result in viral reactivation. Other contra-indications include concurrent eye infection, scarring of the cornea, poor corneal wound healing and severe dry eye.
3 Kerotoplasty (Corneal Transplant Surgery)
(a) Surgical Considerations and Time Required.
In this procedure, a donor cornea is sutured into the host cornea. A special instrument is used to remove the cornea of the eye receiving the operation. The donor cornea is then sutured into place. The procedures are delicate and performed under special operating microscopes. A complete work-up is required prior to the operation. The surgery is performed with either general or local anaesthesia. There are the usual risks associated with the use of anaesthesia. The average time spent in the hospital varies between 3 and 5 days. A recuperation period of 2 weeks to several months is required, depending upon the nature of the activities to be performed. (After surgery, a 6 – 12 month period is required for the eye to stabilise before visual correction can be effectively prescribed.) Thus, it is advisable to operate on the poorer eye while the other eye is still functioning.
Rejection of the donor tissue is the most frequent complication. The rate of rejection is the lowest of any surgical transplant procedure since the cornea does not have blood vessels. Nevertheless, certain cornea will be rejected or lose their clarity. The possibility of rejection is far greater with young people than with older people because of a more active immune system. If rejection occurs, further surgery is required.
(c) Visual Results After Surgery
The surgery is subject to many variables which influence vision. They include the nature of the donor tissue, the healing processes, and the type of surgery required. Following surgery, either eyeglasses or therapeutic contact lenses may be required. Approximately 50% of all patients will be able to achieve adequate vision with eyeglass correction. The eye must stabilise before either eyeglasses or contact lenses may be effectively prescribed; this may require a period of 6 to 12 months. The most frequent difficulty following successful surgery is the presence of moderate or high astigmatism. If this occurs, it will be necessary to fit a lens to provide effective vision. With very high astigmatism, extremely complicated lenses may be required.
(d) Recommendations Regarding Surgery
Corneal surgery for keratoconus is usually not recommended if the patient can satisfactorily wear contact lenses. If the severity of the keratoconus, however, either makes the wearing of the lens unsatisfactory, or results in unsatisfactory vision, then there is no other alternative than the surgical procedure.
A New Procedure in Kerotoconus Management
When it comes to keratoconus there are many fundamental questions surrounding this mysterious eye disease. What causes it? Who contracts it and why? What factors affect its evolution and can it be cured? Many questions are difficult to answer. “Why can’t I see with glasses anymore? Will hard lenses correct my vision and for how long? When will I need a graft? What happens if the graft fails? What vision can I expect following a graft and how long with a graft last?” Patients need reassurance that, in most cases, keratoconus need not lead to a dramatic change in their quality of life. Especially as some have a history of misdiagnosis of their condition, resulting in a series of ineffective treatments. No wonder patients are anxious, frightened, wary and sometimes even angry about their previous experiences with eye care practitioners.
Keratoconus Australia believes it can aid patients because all it’s members have keratoconus. They live with it every day. That gives them a unique insight into the challenges facing patients. Keratoconus Australia aims to provide support for individuals with keratoconus and their families through regular group meetings, help lines, individual counselling and the dissemination of information.
Keratoconus Australia want to do much more. They plan to:
• Support the development of a network of self-help groups throughout Australia.
• Conduct publicity campaigns and seminars to improve community awareness and understanding of keratoconus and it’s impact on those with the conditions, with particular focus on schools and eye carers (optometrists and ophthalmologists). • Publish a regular newsletter with information on a wide range of issues affecting people with keratoconus.
• Act as a lobby group for keratoconus patients to improve health rebates for treatments (contact lenses and solutions, glasses) and corneal surgery and to obtain higher funding for local research into the condition and recognition of keratoconus as a disability.
• Develop a national registry and database on Australians with keratoconus, designed to assist in networking individuals and groups within Australia and to form a basis for future research work.
If you would like to assist Keratoconus Australia or simply wish to draw on their experience with keratoconus, to help new sufferers concerned about their eyesight, please contact them:
Kerataconus Australia P O Box 8188 Camberwell North, Vic 3124 Tel: 0409 644 811 Email: email@example.com Web: www.keratoconus.asn.au