I've been diagnosed with keratoconus. What do I do now? - 1

I've been diagnosed with keratoconus. What do I do now? - 1

This article brings together some questions and answers about the pathology keratoconus to help you understand what it is, what causes it and how your ophthalmologist at Clínica Privada de Oftalmologia (CPO) can help stabilize your disease and improve your vision.

What is keratoconus?     

Keratoconus is a progressive, non-inflammatory disease that causes the cornea to become thinner and more curved, resulting in a cone-shaped cornea. Over time, this greater curvature leads to the development of myopia and irregular astigmatism (a type of astigmatism that is impossible to correct with glasses or contact lenses), making vision progressively lower and poorer quality. Ongoing monitoring and treatment are crucial to prevent significant vision loss.

The cornea is a kind of transparent watch glass, part of the fundamental surfaces of the eye and responsible for focusing light so that you can see well. It also protects the eye from dirt, germs and UV rays.

In people with keratoconus, when light hits the cornea, it refracts in different ways, depending on which part of the cornea is abnormally shaped.

How is keratoconus diagnosed?

• Initially, a technician at the CPO uses a device called an autorefractometer to screen for possible eye pathologies;

• The ophthalmologist will look at the eyes with a device, the slit lamp, which involves shining a vertical beam of light into each eye, this light being coupled to a microscope that allows each layer of the eye to be accurately assessed. This exam assesses the shape of the cornea and can also detect other eye problems;

• If keratoconus is suspected, the ophthalmologist will request a series of tests from the technicians at CPO. The technicians will use the latest and most accurate device available (Pentacam) to carry out an examination called corneal topography, which involves focusing a circle of light on the cornea and measuring the reflection of the light, making it possible to construct various maps of the two surfaces of the cornea (anterior and posterior). It should be noted that this examination, based on Scheimpflug imaging technology, allows for the early detection of keratoconus in subclinical cases.

The need for other complementary diagnostic tests will depend on the clinical judgment of the ophthalmologist who sees you, and will be done on a case-by-case basis.

What are the usual symptoms of keratoconus?

In the vast majority of cases, patients don't know they have keratoconus, not least because it is often unilateral, at least in the early stages. The disease usually manifests itself during adolescence. Some of the symptoms to look out for in keratoconus are as follows:

• Difficulty with night vision;
• Blurred vision;
• Halos or glare around the lights;
• Greater sensitivity to bright lights;
• Headaches or eye irritation associated with eye pain;
• Progressive deterioration of vision that cannot be easily corrected.

If you experience any of these symptoms, you should make an appointment for a specialized keratoconus consultation with one of the following cornea specialists at CPO: Prof. Dr. Tiago Ferreira; Dr. Eunice Guerra; Dr. Samuel Alves e Dr. Bernardo Feijóo.

How can keratoconus affect my lifestyle?

Keratoconus considerably affects vision, which can worsen your quality of life. People with this disease may find it difficult to work, read, watch television or drive. It is also possible for the disease to trigger anxiety, decrease self-confidence and reduce the ability to participate in team sports.

What are the main risk factors that cause keratoconus?

• Genetics: Around 1 in 10 people with keratoconus also have a family member with the disease.

• Inflammation: Irritation and inflammation associated with allergies, asthma and other atopic diseases can contribute to the development of keratoconus.

• Frequent rubbing of the eyes: Intense and frequent rubbing of the eyes can make the cornea thinner and more curved, contributing to the progression of the disease.

• Underlying disorders: Keratoconus is sometimes associated with systemic diseases, such as Down's syndrome, Ehlers-Danlos syndrome, Leber's congenital amaurosis, Marfan syndrome or osteogenesis imperfecta.

• UV light: Ultraviolet light can increase oxidative stress, a physiological condition that contributes to weakening the corneas in eyes already predisposed to the disease.

• Weak collagen: In a healthy eye, there are collagen fibers that help keep the cornea in a normal shape (like a watch glass), free of other protuberances. In the case of keratoconus, the collagen fibers become weaker and therefore cannot maintain the normal shape of the cornea, which causes an increase in its curvature.

• Corneal surgery: In very rare cases, this can cause a change in the shape of the cornea, in much the same way as keratoconus, called corneal ectasia.

What treatments are available for keratoconus?

Spectacles and Contact Lenses:

In the early stages of the disease, it can be corrected with glasses with special lenses. As the condition progresses to mild or moderate stages, increasing irregular astigmatism, the treatment of choice is contact lenses, namely rigid gas-permeable or hybrid lenses, both of which are available at CPO's contactology clinic. You will be referred by your ophthalmologist if he or she deems it appropriate and after your first observation by a cornea specialist. These contact lenses have their own rigidity and a wide diameter, covering the entire surface of the cornea, which makes them effective and comfortable for people with keratoconus. All these types of contact lenses are available at CPO and can be adapted to your case.

However, approximately 20% of patients with advanced keratoconus are unable to tolerate or improve their vision with contact lenses, and it is eventually necessary to resort to surgical procedures to treat the disease.

Crosslinking:

When keratoconus progresses and if the transparency of the cornea is sufficient to maintain satisfactory vision, a treatment called Collagen Crosslinking. This procedure aims to prevent the progression of the disease and consists of applying vitamin B2 and exposing the cornea to ultraviolet (UV) rays, which will increase the mechanical resistance of the cornea. In technical terms, it consists of interlacing the collagen fibers that make up the cornea. These fibers are normally linear and, in this process, they become a kind of "safety net", which gives the cornea more rigidity and resistance, in a safe and highly effective treatment.

Corneal collagen crosslinking is performed using topical anesthesia (just anesthetic drops) and is a completely painless procedure. After the procedure, the improvement in vision, myopia, astigmatism, reduction in corneal curvature and, consequently, improvement in visual quality can last for 6 to 12 months and, in some cases, there is a progressive improvement even after this initial period. The effectiveness of a single treatment can be around 95% on average.

Intra-stromal rings

In certain situations, it will be necessary to resort to another surgical procedure, if the cornea maintains its transparency and adequate thickness, the implantation of intra-stromal ring segments. In OCT, these segments are implanted using the femtosecond laser. The rings are semi-circular segments inserted into tunnels made in the thickness of one of the layers of the cornea (stroma). The aim of this surgery is to standardize the shape of the cornea, allowing the use of glasses, contact lenses or the implantation of a phakic intraocular lens (ICL) at a later stage, in order to correct any residual refractive error (myopia or astigmatism). In these cases, the femtosecond laser is currently an essential aid, as it allows the ring segment(s) to be precisely implanted at an exact depth along their entire path, something that is impossible in manual surgery without the use of this type of laser.

In the most advanced and severe cases, or in cases where there is opacity , acorneal transplant (keratoplasty) is the only treatment option. This surgery, currently using the most advanced techniques, consists of transplanting only the superficial layers of the cornea, in order to preserve the deeper, healthier layers, thus reducing the risk of transplant rejection and increasing survival (years in which the transplant remains transparent and functional).

Can I go blind if I have keratoconus?

Generally, the disease does not cause total blindness. However, as keratoconus progresses, it can cause progressive visual impairment, including blurred vision at a distance, blurriness, glare, high astigmatism, extreme sensitivity to light and even loss of vision that can, in extreme cases, be classified as "legal blindness".

Does keratoconus affect both eyes?

Yes, in approximately 90% to 95% of keratoconus cases, the disease manifests itself in both eyes. However, the rate of progression and the time of onset of the disease are different for each eye.

If you would like to find out more about this pathology, consider the following source: NCBI