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Ashraf Armia Eye Clinic

Keratoconus

Seeing Clear with Corneal Rings

If you have been told that you have keratoconus, you’re probably anxious to address the issue and begin seeing clearly again. Enter corneal ring implantation, a safe, effective, quick procedure that is completely reversible. Corneal rings also may be an option if you have mild to moderate nearsightedness; however, thanks to advancements in technology, these days most patients with nearsightedness opt for LASIK.

Corneal rings, also called corneal ring segments or intrastromal corneal ring segments (ICRS), are small plastic devices implanted to alter the shape of the front portion of the eye to provide you with clear vision. In the U.S., Intacs are the most popular brand of corneal rings.

Why Have Corneal Rings Implanted?

Corneal ring segments have a number of amazing benefits.

For one, the procedure time is very quick. Though you will need to remain at the surgical center for an hour or two, the actual implantation of corneal rings only takes around 15 minutes per eye.

Nearly 100 percent of patients who undergo this procedure meet the requirements for driving without corrective lenses following surgery, and more than half achieve 20/20 vision or better.

The procedure is also completely reversible. If for some reason you don’t like the results – or if your vision changes – the corneal rings can be taken out.

Implanting corneal ring segments is also very safe – and it’s now safer than ever thanks to advances in laser technology.

What’s more, you won’t feel your corneal rings, and other people won’t see them.

Corneal rings are made of a clear, biocompatible substance, so they can be left in the eye forever unless you have reason to remove them.

If you’re considering corneal ring segments to correct your nearsightedness, there are additional benefits. Specifically, if you are at high risk for a condition called ectasia, you may want to speak to your surgeon about the benefits of having corneal rings implanted, rather than having LASIK or another laser vision correction procedure. Corneal rings also eliminate the risk of tiny refractive errors that can arise as a result of LASIK.

Potential Risks & Complications

Like any surgical procedure, corneal ring implantation poses certain risks (most are rare), including:

  • Reduced vision
  • Glare or halos around lights
  • Infection
  • Blurriness
  • Night vision
  • Fluctuating vision

It’s also possible that you will need glasses for certain tasks following your procedure.

Most complications associated with corneal ring segments are temporary and go away on their own. And remember, if you do have problems with them, they can be removed.

Though corneal rings can be used to correct mild to moderate myopia (nearsightedness), they cannot correct hyperopia (farsightedness) or astigmatism.

Are You a Candidate for Corneal Ring Segments?

To be considered a good candidate for corneal rings you must be at least 21 years of age. Your vision must be stable for the year leading up to your surgery. Your eyes must be healthy, with no disease and no compromised vision stemming from injury.

You will not be considered a candidate for corneal ring implantation if you have severe myopia or astigmatism. In fact, patients with a measurement higher than -3.00 diopters of myopia and/or -1.00 diopters of astigmatism are not considered candidates.

Talk to qualified eye surgeon to learn if you are a candidate for corneal ring implantation.

 

COLLAGEN CROSSLINKING : A PARADIGM SHIFT IN KERATOCONUS MANAGEMENT

This revolutionary new treatment offers a new hope in patients of progressive Keratoconus

Keratoconus is a bilateral ocular disorder in which the cornea assumes a conical shape due to thinning of the stromal collagen tissue.It is a relatively frequent disease with an incidence of 1 in 2000 in the general population.It classically has its onset at puberty and is progressive until the third or fourth decade of life when it usually arrests.

Keratoconus can be detected clinically by slit lamp examination by an Ophthalmologist and the diagnosis can be confirmed by corneal topography.

Treatment options

Currently, the mainstay of treatment for Keratoconus include glasses and / or specially designed rigid gas permeable contact lenses which offer good quality of vision in advance cases keratoconus can be corrected surgically by corneal grafting and placement of intracorneal rings. However, all these treatment options only correct the refractory error in Keratoconus and do not address the issue of progression of the disease. Collagen Cross Linking is a new modality of treatment that aims to arrest progression of keratoconus.

What is Collagen crosslinking ?

The corneal collagen is crosslinked with the help of ultraviolet rays ( UVA ) and a photosensitiser, Riboflavin , thus enhancing the rigidity of corneal tissue and stabilizing the condition

Who is a suitable candidate for Collagen crosslinking ?

Patient must be a proven case of keratoconus with documented progression of the disease.
Patient's corneal thickness must be at least 400 microns.
Patient should not be pregnant or nursing.

How is Collagen crosslinking performed ?

The treatment is performed under topical anaesthesia with the patient in a lying down posture in the sterile environment of the operating room. The patient's corneal epithelium is gently removed, following which Riboflavin solution is applied every 5 minutes for the first half an hour. Thereafter the patient's cornea is exposed to UVA light for half an hour. The treatment is painless and lasts for an hour, at the end of which the eye is patched. The cornea is the clear, transparent dome in front of the "black portion" of the eye. It is also the main focusing surface, which converges light rays as they enter the eye to focus on the retina. It is thus the most important part of the optical apparatus of the Eye. Loss of transparency directly results in loss of vision.

When can the patient resume normal routine ?

After the treatment, patient will be able to resume work within 3 to 4 days.Care should be taken to avoid entry of water into the eyes during this period.The use of contact lenses may be resumed 6 weeks after treatment.

How often must the patient come for follow up ?

The surgeon will examine the patient's eye daily for the first 2 to 3 days until the epithelial healing is complete. Eye drops will be used for 4 months. Patient will have to come for follow up at 6 weeks, 3 months, 6 months, 1 year and 2 years after the procedure.

Can both eyes be treated at the same time?

If both eyes are suitable for Collagen crosslinking, the treatment is performed on one eye at a time .The timing of treatment of the second eye is best decided in consultation with your ophthalmologist.

What are the possible side effects of the procedure?

A foreign body sensation, irritation or watering accompanied by pain is not uncommon on the day of treatment. Analgesics for relief from pain will be prescribed , and the pain usually subsides within 24 hours. Dryness of the eyes frequently follows this treatment and may last for 6 to 8 months. Tear lubricants are therefore recommended for the period.

Concerns using UVA light

UVA light can potentially harm the vital cell layer of the cornea known as the endothelium as also the crystalline lens and the retina. However, the use of riboflavin and the choice of the wavelength of UV light used, substantially reduces the intraocular penetration of UV rays to negligible levels. Potential side effects are therefore avoided. It is mandatory to perform a preoperative measurement of the corneal thickness and to exclude patients with corneal thickness less than 400 microns .

The 3 & 5 year results of the Dresden clinical study on collagen crosslinking in human eyes has shown arrest of progression of keratoconus in all treated eyes Collagen crosslinking has thus emerged as a safe and effective , inexpensive non surgical promising new treatment for Keratoconus to slow the progression of the disease and to delay or avoid corneal graft surgery. With more long term experience in the arena , prophylactic treatment of Keratoconus might become possible with collagen crosslinking.

In the early stages, spectacles or soft contact lenses may be used to correct vision. As the cornea becomes thinner and steeper, rigid gas permeable (RGP) contact  lenses are often required to correct vision more adequately. In very advanced cases, where contact lenses fail to improve vision, a corneal transplant may be needed.

Changes caused by keratoconus can take many years to develop. For this reason we monitor those with the condition and invite them back for repeat assessments for up to five years from an initial visit. 

When a person with keratoconus attends a clinic at Moorfields , the following tests might be performed;

1. Vision (reading chart)

2. Refraction (spectacle test)

3. Corneal scan (Pentacam) 

Any necessary contact lens checks will also be undertaken.  The results are compared with those from your previous visits. If the results are getting steadily worse, we will discuss with you whether you need to undergo corneal cross-linking (CXL). 

CXL is a new treatment that can stop keratoconus getting worse. It is effective in more than nine out of 10 patients, with a single 30-minute day-case procedure, but it is only suitable where the corneal shape is continuing to deteriorate.  Beyond a certain stage, if the cornea is too thin, it could be unsafe to perform the procedure. Usually in people in their late 30s, the cornea naturally stiffens and CXL is generally not required. Below this age, the cornea is more flexible and disease progression (and worsening vision) are more likely to occur. 

 

To diagnose keratoconus, your eye doctor (ophthalmologist) will review your medical and family history and conduct an eye exam. He or she may conduct other tests to determine more details regarding the shape of your cornea. Tests to diagnose keratoconus include:

  • Eye refraction. In this test your eye doctor uses special equipment that measures your eyes to check for vision problems. He or she may ask you to look through a device that contains wheels of different lenses (phoropter) to help judge which combination gives you the sharpest vision. Some doctors may use a hand-held instrument (retinoscope) to evaluate your eyes.
  • Slit-lamp examination. In this test your doctor directs a vertical beam of light on the surface of your eye and uses a low-powered microscope to view your eye. He or she evaluates the shape of your cornea and looks for other potential problems in your eye. The doctor may repeat the test after you've had eyedrops applied to dilate your pupils. This helps with viewing the back of your eye.
  • Keratometry. In this test your eye doctor focuses a circle of light on your cornea and measures the reflection to determine the basic shape of your cornea.
  • Computerized corneal mapping. Special photographic tests, such as optical coherence tomography and corneal topography, record images of your cornea to create a detailed shape map of your cornea's surface. The tests can also measure the thickness of your cornea.

Keratoconus Symptoms & Diagnosis


The earliest signs of keratoconus are usually blurred vision and  frequent changes in eye glass prescription, or  vision that cannot be corrected with glasses. Symptoms of keratoconus generally begin in late teenage years or early twenties, but can start at any time.


Other symptoms include:

  • Increased light sensitivity
  • Difficultly driving at night
  • A halo around lights and ghosting (especially at night)
  • Eye strain
  • Headaches and general eye pain
  • Eye irritation, excessive eye rubbing

Keratoconus, especially in the early stages can be difficult to diagnose and all of the above symptoms could be associated with other eye problems. Simply recognizing symptoms does not by itself diagnose keratoconus.

Keratoconus requires a diagnosis from a competent eye doctor trained not only in recognizing the symptoms but also observing signs of keratoconus through direct measurement as well as inspection of the cornea at a microscopic level using a slit lamp.