KERATOCONUS, C3R, LASIK XTRA, ICL, INTACS

KERATOCONUS (CONE SHAPED CORNEA)

Keratoconus is a non-inflammatory thinning and anterior protrusion (ectasia) of the cornea that results in steepening and distortion of the cornea, altered refractive error, and decreased vision. Keratoconus is a complex condition of multifactorial etiology. Both genetic and environmental factors are associated with it. Evidence of genetic etiology is not very certain but includes familial inheritance in some cases, and association with other known genetic disorders.

Keratoconus is a common bilateral corneal condition, occurring in more than 1 in 1000 people. The condition typically starts in adolescence and early adulthood.

Usually one eye is involved more than the other. It is more common in people with allergies or those who rub their eyes frequently.

Despite its uncertainties, keratoconus can be successfully managed with a variety of clinical and surgical techniques, and often with little or no impairment to the patient's quality of life.

The cornea is the clear window on the front of the eye. It is usually a regular spherical dome in shape. The substance of the cornea consists of hundreds of layers that are linked to each other by a substance called collagen. If these collagen cross-links between layers are lost due to keratoconus, there is a progressive corneal thinning and stretching which gradually progresses, often in both eyes. Normal pressure within the eye causes the cornea to bulge forward into an irregular cone shape. When light enters the eye, it first passes through the cornea. If the cornea has turned conical, there is distortion of the image. The eye develops astigmatism (cylindrical errors) and myopia [shortsightedness] and the vision may become severely blurred.

A simulation of the multiple images seen by a person with keratoconus

RISK FACTORS

Reported risk factors for keratoconus include eye rubbing, a family history of keratoconus, genetic predisposition, certain systemic disorders such as Down’s syndrome, ocular allergy, connective tissue disease, and long-term rigid contact lens wear. It affects men and women in equal proportions and is bilateral in 90% of patients.

SYMPTOMS

At early stages, the symptoms of keratoconus may be no different from just having the need for spectacle correction. As the disease progresses, the vision deteriorates. Keratoconus can cause substantial distortion of vision, with multiple images, streaking and sensitivity to light.

DIAGNOSIS

This is usually done by an ophthalmologist with a detailed eye examination. Diagnosing mild or early disease may be difficult as it does not show any identifiable signs on slit-lamp examination. A more definitive diagnosis can be obtained using pentacam or advanced scan corneal topography, in which an automated instrument projects an illuminated pattern onto the cornea and determines its shape from analysis of a digital image.

Keratoconus Diagnosis - OPD Scan

Keratoconus Diagnosis - OPD Scan

The topographical map reveals distortions or scarring in the cornea, with keratoconus revealed by a characteristic steepness of curvature which is usually below or around the centre of the cornea. The topography is used for assessing its rate of progression. Unilateral cases tend to be uncommon though one eye is generally more affected than the other.

TREATMENT

1.CONTACT LENS

Treatment of mild keratoconus is geared towards eliminating or reducing the myopia and astigmatism, at times with spectacles alone.

As the condition progresses, spectacles may no longer provide the patient with a satisfactory degree of visual acuity, and most doctors will move to managing the condition with rigid contact lenses.

  • Rigid gas permeable contact lenses or advanced Rose-K and Scleral contact lenses for keratoconus improve vision by means of tear fluid filling the gap between the irregular corneal surface and the smooth regular inner surface of the contact lens, thereby creating the effect of a smoother cornea. The irregular cone needs doctor’s expertise to produce a contact lens with optimal contact, stability and steepness. Some trial-and-error fitting might be necessary.
  • A soft contact lens has a tendency to conform to the conical shape of the cornea, thus diminishing its effect. These do not however prove effective for keratoconus patient. New soft scleral contact lenses are proving to be very effective though expensive.
  • Some patients also find good vision correction and comfort with a "piggyback" contact lens combination, in which gas permeable rigid contact lenses are worn over soft contact lenses, providing clarity of vision and comfort.
Precaution with contact lenses:

There is a small risk of infection with use of contact lens so it is important to strictly follow the hygiene instructions given when the contact lenses are fitted.

Contact lenses are used as temporary measures of treatment, but do not, unfortunately, slow down the rate of progression of the cone.

2. Surgery :

In about 10% to 20% of keratoconus patients the cornea may become extremely steep, thin and irregular or the vision cannot be improved sufficiently with contact lenses. The cornea may then need to be replaced surgically with a corneal transplant or grafting (keratoplasty), DLK etc. Visual recovery after a transplant takes a long time - sometimes as long as a year to 18 months - to settle down and there is a strong possibility that the eye will still need to be fitted with a contact lens afterwards in order to see properly .

There is also a risk of the transplant rejecting afterwards, although a majority of corneal transplants done for keratoconus are successful.

Kera Rings, Intacs or ICL are used in appropriate cases.

3. CORNEAL COLLAGEN CROSSLINKING WITH RIBOFLAVIN - C3R ®*, CXL

With current methods using rigid contact lens or intra corneal ring segments, only the refractive error (spectacle numbers) can be corrected, but it has very little effect on the progression of keratoconus.

What is collagen cross-linking?

A new treatment for keratoconus which has shown great success is Corneal Collagen Crosslinking with Riboflavin (C3-R®*), a one-time application of riboflavin eye drops to the eye. C3R causes the collagen fibrils to thicken, stiffen, and crosslink & re-attach to each other, making the cornea stronger and more stable thus convincingly halting the progression of the disease.

The riboflavin, when activated by approximately 30 minutes illumination with UV-A light, augments the collagen cross-links within the stroma and so recovers some of the cornea's mechanical strength and in some cases even reverse it, particularly when applied in combination with intracorneal ring segments.

Before C3R Treatment

After C3R Treatment

How is CXL, C3R treatment done?

The treatment is performed in our operation theatre under complete sterile conditions. The treatment is performed under topical anesthesia (using anesthetic eye drops). The surface of the eye (cornea) is treated with application of Riboflavin eye drops for 30 minutes. The eye is then exposed to UVA light for 30 minutes. Hence, the treatment takes about an hour per eye. After the treatment, antibiotic eye drops are applied; a bandage contact lens may be applied, which will be removed by our doctor during the follow up visit.

C3R CSO Vega - Keratoconus Treatment

Who can benefit from this treatment ?

Patients may need to continue to wear spectacles or contact lenses (although a change in the prescription may be required) following the cross-linking treatment;The main aim of this treatment is to arrest progression of keratoconus, and thereby prevent further deterioration in vision and the need for corneal transplantation.

Like all treatments, this procedure is most beneficial when performed at the earliest possible stage of Keratoconus when the visual and mechanical damage to the cornea is minimal.

Biomechanical measurements have shown an impressive increase in corneal rigidity of over 300% after crosslinking. The Dresden, Germany clinical study has shown that in all treated eyes the progression of keratoconus was stopped ('freezing'). In over 53% of those eyes there was a slight reversal and flattening of the keratoconus ;

What are the risks and consequences involved?

The treatment involves the outer layer of the cornea. There is therefore, some amount of discomfort and a short-term haze.

There is inability to wear contact lenses for several weeks after the treatment

Changes in corneal shape necessitates fitting of a contact lens or a occasional change in spectacle correction.

4. Intacs

Intacs / Corneal ring segment insert is another surgical alternative to corneal transplant / number correction in keratoconus etc. It involves insertion of intrastromal corneal ring segments. A small incision is made in the periphery of the cornea and two thin arcs of polymathy methacrylate are pushed in between the layers of the stroma on either side of the pupil before the incision is closed. The segments then push out against the curvature of the cornea, flattening the peak of the cone and returning it to a more natural shape. The procedure, carried out on an outpatient basis under local anesthetic, offers the benefit of being reversible and even potentially exchangeable as it involves no removal of eye tissue.

The principal intrastromal ring available is known by the trade name Intacs. Internationally, Ferrara rings are also available. Intacs are a patented technology and are placed outside the optical zone, whereas the smaller prismatic Ferrara rings are placed just inside the 5 mm optical zone. In common with penetrating keratoplasty, the requirement for some vision correction in the form of spectacles or hydrophilic contact lenses may remain subsequent to the operation. Potential complications of intrastromal rings include accidental penetration through to the anterior chamber when forming the channel, postoperative infection of the cornea, and migration or extrusion of the segments.

5.LASIK XTRA

Is used in keratoconus suspect patients and borderline keratoconus patients for stabilization of disease and correction of glasses.

ADVANTAGES OF CROSS LINKING, C3R, CXL, Intacs CXL-Extra
  • Permanent
  • Simple- Single- one hour treatment
  • One time treatment
  • Stops the progress and causes regression of disease
  • No incisions as in Intacs or Corneal ring segments
  • No follow up sittings required
  • No need for admission
  • No major precautions
  • No injections or stitches
  • Quick recovery with short follow up
  • Does not need eye donation as in corneal transplant
  • Inbuilt monitor & software programming.

6. IMPLANTABLE CONTACT LENS OR PHAKIC I.O.L., TORIC ICL

Toric ICL is being used for correction of refractive errors (glasses) in keratoconus patients. For details see under LASIK.

Only certified ICL Eye Hospital in the region

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