Keratoconus: how to protect your eyes from a gradual drop of vision

this condition is one of the  most popular chronically or slowly progressive ocular conditions that takes years to affect and impair a person’s vision. In this condition the cornea, the clear window at the front of the eye loses its natural spherical contour, and becomes thinned out ,bulging out at weak points and assuming a conical shape. This abnormality of shape and contour affects the bending of light rays at the corneal interface , causing irregular bending and defocus of these rays when they fall onto the retina, leading to drop of visual clarity and acuity. The condition affects one or both eyes with varying degrees, and the average age of affection is between 15 -25 years . 

What causes keratoconus?

The actual cause is unknown yet, but  research has shed light that a deficiency of certain building enzymes within the corneal stroma.  

The wear and tear that is constantly repaired by these enzymes is slowed down, causing excessive accumulation of diseased collagen fibers and oxygen free radicles, leading to weakening of the corneal stromal bridges, and hence weakness  and forward bulge of the cornea. 

Research has also linked the condition to certain hereditary factors and genetic conditions, which highlights the importance of family history in this condition. 

In addition, excessive unprotected exposure to sunlight and constant eye rubbing have also been implicated. Also, the misuse of poor-quality contact lenses has also been added to the predisposing factors. 

Available treatment options:

At the early stages of the disease , glasses and/or rigid contact lenses (Rose -K, RGP) can be used to treat the condition according to your doctor’s decision. 

As the condition worsens however, your ophthalmologist or eye surgeon may resort to corneal collagen cross linking or intracorneal ring implantation. 

What are the common symptoms for keratoconus?

Patient’s with this condition notice that their vision becomes gradually blurred and unclear with frequent change of their glasses prescription.

 This subtle symptom may progress over years or months and may affect both eyes and one eye more than the other .

 the most common early symptoms include 

  • Blurring of distant and near vision despite wearing the proper optical correction
  • Straight lines appear bent or skewed at different angles
  • Increased sensitivity to ,light and increased sense of haloes around the light 
  • Redness and swelling of the eye

Later symptoms become more ominous and include 

  • Increased blur and visual distortion that does not respond to  any form of optical correction
  • Intolerance to contact lenses
  • Progression of myopia and astigmatism

 

What are the various surgeries that can be used to treat the condition?

Corneal collagen cross linking:

 this procedure uses ultraviolet light rays and concentrated vit B2 eye drops to create and strengthen the interconnecting bridges between the collagen fibers in the corneal stroma, making it stronger and less liable to bulge. 

The vitamin B2 drops are instilled onto the eye over a period of 30 minutes, this is followed by further 30 minutes of ultraviolet exposure. 

intracorneal ring implantation

 these semicircular devices made of PMMA are inserted into tracks created within the stroma of the diseased cornea and help to restore visual clarity and acuity by flattening the cones and increasing corneal thickness therefore creating a smoother refractive surface and regular light refraction onto the retina.

Corneal implantation

 if the cornea is severely thinned out or damaged you might need to have it partially or fully replaced by  donor tissue. This surgery restores the natural anatomy of the cornea and may provide best visual outcomes for some cases

 

Not all keratoconus patients have the same condition or follow the same treatment protocol, or  respond to the same treatment modality, each treatment option is specifically tailored according to the presented case 

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About the doctor

A consultant specializing in corneal, cataract and Glaucoma Surgery and Refractive surgery in Egypt, Assistant Professor of Ophthalmology – Ain Shams University, Consultant cornea, cataract, and Glaucoma Surgery and Refractive Surgery, Fellow of the Royal College of Physicians and Surgeons of Glasgow, UK.

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