Keratoconus is a progressive disorder that causes thinning and distortion of the cornea, resulting in blurry and distorted vision, often affecting both eyes differently. Diagnosis involves assessing the curvature, thickness, and cone morphology of the cornea, with treatment options ranging from corrective lenses to surgical procedures like corneal inserts and transplants. Collagen cross-linking is a promising procedure aimed at stabilizing the cornea and preventing further progression, with a high success rate but some associated risks.

1. {
Understanding Keratoconus
Saleh Hassan
May 2018

2. Background
o Cornea: transparent front part of the eye that deflects light rays
which focused into a point of sharp focus. For a good vision the
focus point must be on retina
o Keratoconus is a disorder of the eye which results in progressive
thinning of the cornea and bulging like a cone
o Changing the shape of the cornea brings light rays out of focus
o As a result, your vision is blurry and
distorted, making daily tasks like reading
or driving difficult
Normal eye Keratoconus

3. KeratoconusNormal
Blur vision Distorted vision

4. o Unknown
o It is believed that genetics, the environment and the endocrine
system all play a role in keratoconus
Causes
Source of causes: https://www.nkcf.org
 Normal eye Keratoconus
• Collagen fibers
(tiny fibers hold cornea in place
and keep it from bulging)
• Weak collagen fibres
• Protective antioxidants
(molecules that inhibit the oxidation)
(Oxidation is a chemical reaction produce radicals
absorbed from environment Ex: O*,
leading to chain reactions
that may affect signal transduction
and damage corneal cells)
• Protective antioxidants

5. o Early stages
• mild blurring of vision
• slightly distorted vision, where straight lines look bent or wavy
• increased sensitivity to light and glare
• eye redness or swelling
Symptoms
o Later stages
• more blurry and distorted vision
• increased astigmatism
(when your eye cannot focus as well as it should)
• not being able to wear contact lenses
o Keratoconus affects both eyes,
and can lead to very different vision between the two eyes

6. o Measuring the shape of cornea by several devices
o Step1 Slit-lamp
determines the damage of cornea
o Step2 Corneal Topography
more accurate details and showing
how the disease is progressing
Diagnosis
o There are three levels of severity when it comes to Keratoconus and it
determined by several parameters

7. 1) Testing Steepness of greatest Curvature
40-45D is mild
52 D is considered advance
Above 52D is severe
2) Thickness of the Cornea
Mild- 506µm
Advanced- Less than 446µm
3) Morphology of the Cone
If the cone is sagging it too is an indicator of the
advancing of the disease.
Parameters

8. Keratoconus cornea
• Non symmetrical
• Inferior Steeping
Normal cornea
• Symmetrical
• No excessive steeping
Topography map
Blue shows the flattest areas, and red the steepest

9. o Depend on level of condition
1) Lenses: Level (Mild – moderate)
• Eyeglasses or Contact lenses:
- correct blurry and distorted vision
- glasses or lenses changes as the shape of cornea changes
• Hard contact lens(RGP):
- Next step of treating progressive keratoconus
- Can be made to fit your cornea
Treatment
Hard contact lens (RGP)

10. • Piggyback lenses
- a hard contact lens on top of a soft one
- used if rigid lenses are uncomfortable
• Hybrid lenses
• Scleral lenses
- useful for very irregular shape changes
in your cornea in advanced keratoconus
- sits on the white part of the eye
Lenses
Hybrid lenses
How scleral vaults on
misshapen cornea

11. • Small device implanted in the eye to correct
vision
• Procedure:
Making small incision in the
cornea and inserts two crescent or semi-
circular shaped ring segments between the
layers of the corneal stroma , one on each side
of the pupil
• Uses:
Treatment of mild– moderate
keratoconus
Near sighted vision
Surgery: Corneal Insert
A pair of corneal rings after
insertion into the cornea
Stroma

12.  Outcomes:
- short-terms
central flattening of the cornea were reported in all of the studies
• keratometric was reduced to (2.14 to 9.60 D)
- medium and long-terms
ICRS did not stop cone progression
• Useful for improving the contact lens tolerance for the residual refractive
error.
• Carrasquillo et al found an 81% improvement in contact lens tolerance
after Intacs implantation in keratoconus and post-LASIK ectasia
 Complications
Rare. Its reversible. No tissues need to be removed
Surgery: Corneal Insert
Source: http://eyewiki.aao.org

13. o Required when damage is severe
o It’s a surgical procedure to replace part of your cornea with corneal tissue
from a donor
o Procedure
Eye drops to help you to relax
The central damage part is removed
The healthy donor cornea is securely sewn into place
o Outcomes
Generally is very successful
o Complications
New cornea rejection
Poor vision
Astigmatism
Inability to wear contact lenses
Infection
Surgery: Cornea transplant
Corneal transplantation

14. Background
• Cross-link is a bond that links a polymer chains to another whether its
synthetic or natural such as Protein
• In chemistry when polymer chains are cross-linked, the materiel is
rigified
• Collagen fibers are fibers that hold cornea together made of proteins
How it works
• Collagens + Riboflavin(Vitamin B2)
Surgery: Collagen cross-linking
Activation
UV
New bonds between
collagen fibers
• The result is a cornea that is stiffer and more resistant to any change in
its shape

15. Aim
• Stop the progression & prevent from getting worse
Procedure
• the epithelium is first disrupted
• Riboflavin (vitamin B2) is then applied to the eye
• eye is exposed to UV light
Outcomes
• Success rate is more than 95% for epi-off treatment(epi is removed by
cotton bud then the normal procedure. thin bandage contact lens is
placed on the eye at the end for 24–72 hours)
Complications
• Small risk of infection
• The procedure don’t causing bleeding due to affected cornea dosent have
blood
• The UV only penetrate the cornea not deeper structure of the eye
Corneal cross-linking
Source: https://visioneyeinstitute.com.au