Keratoconus is a generally bilateral but asymmetric corneal ectasia, which involves thinning of the corneal thickness,
gradual corneal protrusion and irregular astigmatism that is generally progressive and can reach elevated levels.
Onset is normally during puberty with 75% of cases being diagnosed before the age of 25 years. It continues to
progress until the third decade of life, after which progression often slows down. The severity of its progression is
partly associated with how early it appears.
Although evidence on the influence of sex in onset and progression is inconsistent, there appears to be a higher
tendency in males.
2. Presenter
Mohamed said Ibrahim
Careers:
• Key Account sales Manger and training, Nikon Lenswear middle east
• Sr.Optometrist, Hadi Hospital
• International Member of the American Optometric Association
• Certified International Professional Trainer (CIPT)
• Ambassador of the Arab British Academy for Higher Education
• Advanced Member of the UK Professional Board
• Trainer of BARAKA AND C&CO. Optics (earlier)
• Demonstrated and lecturer of the High optics technology institute (earlier)
Educational:
PhD in visual behavioural rehabilitation for vision defects
Master Degree of projects management in optics and vision sciences by the
faculty of projects management at Maryland University, USA
BS.C in optics technology and vision science
achieved degree of many short diplomas in health, patient care, customer
service, business administration.
Experience:
More than 15 years of experience for optical shops, optical products, and
optometry clinic
Mohamed Said Ibrahim
mm.Said2004@ymail.Com
5. Mohamed Said Ibrahim
mm.Said2004@ymail.Com
CORNEA
It is a transparent Tissue, the most sensitive part of the body.
it is the most powerful refractive where its power is two-thirds of
the power of the eye, equivalent to about 40.0 to 45.0 dioptres, the
refractive index is (n = 1.376)
A protective barrier from infection and trauma.
The corneal epithelium is one of the fastest healing tissues in the body.
The stroma makes up 90% of the corneal structure.
The Endothelium acts as a water pump to maintain proper tissue
hydration.
Both corneal segments and layers are designed towards one end
which is the clarity and transparency of the cornea.
6. Mohamed Said Ibrahim
mm.Said2004@ymail.Com
CORNEA
The front surface is elliptical (horizontal at 180 degrees equals
approximately 11.7 mm, vertically at 90 degrees equals
approximately 10.6 mm).
The back surface is circular in shape (11.7 mm).
The curvature of the surface or curvature is expressed by the
word keratometry, which shows the strength of each direction
on the surface of the cornea (the average anterior diameter of
the curvature is 7.2-8.4 millimetres). .
The thickness of the center (about 535 microns, which is
equivalent to about half 0.5 millimetres), which is thinner than
the peripheral circumference (about 660 microns = 0.66 mm).
7. Mohamed Said Ibrahim
mm.Said2004@ymail.Com
CORNEAL TOPOGRAPHY
Cool colours (Violet, blue, azure) Flatter surfaces
Warm colours (orange, red) Steeper surfaces
Normal (green, yellow) Normal surfaces
COLOUR MAP
8. Mohamed Said Ibrahim
mm.Said2004@ymail.Com
CORNEA
The Pentacam uses Scheimpflug imaging and, like the Orbscan,
measures both elevation and pachymetry using the same data set.
The Pentacam has been shown to have excellent agreement with
the ultrasound pachymeter with regard to central corneal
pachymetry in both pre and post LASIK eyes
Normal corneal thickness of 535 to 555 micron
Pachymetry
12. Mohamed Said Ibrahim
mm.Said2004@ymail.Com
KERATOCONUS (Kc)
The Cornea Assumes A Conical Shape Because Of Thinning
And Protrusion.
A Progressive, Non-inflammatory, Bilateral (But Usually
Asymmetrical) Ecstatic Corneal Disease, Induces Irregular
Astigmatism, Myopia Leading To Mild To Moderate Impairment
In The Quality Of Vision.
Onset is age 16 years, Shows no gender predilection.
Definition
Ghosting/ monocular diplopia
Glare at night , Haloes around lights
Blurred/ distorted vision
Frequently changing spectacle Rx and axis of astigmatism
Poor repeatability of subjective refraction
Symptoms
16. Mohamed Said Ibrahim
mm.Said2004@ymail.Com
KERATOCONUS Signs
Vogt striae
vertical tension lines
in posterior cornea
Fleischer ring
iron ring around base of cone
Munson sign
bulging of lower lid
on downgaze
Rizutti sign
conical nasal reflection
with temporal illumination
18. Mohamed Said Ibrahim
mm.Said2004@ymail.Com
KERATOCONUS
Based on type of cones :
1. Round or nipple :
Most common, less than 5 mm in diameter , Cone-lies in
centre towards inferior nasal quadrant.
2. Oval cone :
Diameter > 5 mm; often displaced inferiorly.
3. Globus cone :
diameter more than 6 mm diameter, overall steepening , 75%
of cornea affected.
CLASSIFICATION
19. Mohamed Said Ibrahim
mm.Said2004@ymail.Com
KERATOCONUS CLASSIFICATION
Based on severity of curvature :
1. Mild < 45 D in both meridians
2. Moderate 45-52 D in both meridians
3. Advanced > 52 D in both meridians
4. Severe > 62 D in both meridians
20. Mohamed Said Ibrahim
mm.Said2004@ymail.Com
KERATOCONUS Management
- The Routine Follow Up Is The Mandatory For All Keratoconus Patients
- All Optical Solutions (Eyeglasses & C.L) Are Present Pre And Post Surgeries
Based on Keratoconus Severity :
MILD MODERATE ADVANCED
Spectacles
contact lenses:
Soft or hard or Hybrid
Collagen Cross-linking (CXL)
Spectacles
contact lenses:
Soft or hard or Hybrid
Collagen Cross-linking (CXL)
Intracorneal ring segments (ICRS)
Penetrating keratoplasty (PK)
Deep Anterior Lamellar (DALK)
Descemet Stripping Automated
Endothelial (DSAEK)
Descemet Membrane
Endothelial (DMEK)
21. Mohamed Said Ibrahim
mm.Said2004@ymail.Com
KERATOCONUS Management
CONTACT LENSES
Soft contact lenses : single soft C.L
Rigid gas permeable lenses : single hard C.L
Combined lens system : Soft + Hard
- Piggy back system : Rigid lens fitted over a hydrogel
lens
- Hybrid lens system : fuse a soft rim onto a hard
central portion
Fully Keratonic Family Lenses :
- Rose-k lenses
- Scleral and mini scleral lenses
PIGGY BACK SYSTEM
Soft C.L
Scleral/mini scleral
Hard C.L
22. Mohamed Said Ibrahim
mm.Said2004@ymail.Com
KERATOCONUS Management
CONTACT LENSES FITTING PHILOSOPHY
FLAT FITTING
- early keratoconus
- The Entire Weight Of The Lens On The
Cone.
- Apical Touch, Good visual acuity.
- acceleration of apical changes.
- corneal abrasions
APICAL CLEARANCE
- Resting on the paracentral cornea.
- clears the central cornea.
- minimize trauma to the central cornea.
- poor tear film, bubbles under the lens,
poor visual acuity.
- the weight of the contact lens between the
cone and the peripheral cornea.
- a thin band of touching near the edge of the
lens
THREE-POINT TOUCH
26. Mohamed Said Ibrahim
mm.Said2004@ymail.Com
KERATOCONUS Eye Refraction
1. Visual Acuity (VA) :
- Distance unaided VA, monocular VA, binocular VA.
- Distance aided VA, monocular VA, binocular VA.
- Pinhole Visual Acuity (PH VA), aided monocular VA is worse.
- Near VA, aided VA, binocular VA.
2. Best Vision Sphere Refraction :
- Most common is Minus to correct Myopia but trial of Plus is also require regarding Irregular
Astigmatism.
- Best Visual Acuity with more plus or less minus.
3. Sphero-Cylindrical Refraction :
- Jack son cross cylinder (Test 4 main Axis – 90/180 and 35/145)
- JCC cylinder power ( add -0.50cyl will add +0.25sph).
- Refine the axis again by JCC.
4. +1 Test and Binocular Balance :
- Refine SPH Monocular and binocular for BCVA.
5. Near Refraction :
- Near VA, new Rx VA, binocular VA.
- Adjust Powers Sph & Cyl and Axis for Near BCVA.
Visual Acuity
Best Vision
Sphere
Sphero-
Cylindrical
+1Test/Binocular
Near Refraction
Based on Keratoconus Severity – Subjective Refraction (Trial and Error) :
27. Mohamed Said Ibrahim
mm.Said2004@ymail.Com
REFERENCES
Management of Optical measurements in ophthalmic health care, Mohamed Said Ibrahim, 2020
Step by Step Reading Pentacam Topography, second edition, Dr. Mazen M Sinjab, 2015
Oxford Handbook of Ophthalmology, Fourth edition International edition,2018
Refractive Error Training Package, Student Manual, Brien Holden Vision Institute, Edition 2012
American Academy of ophthalmology, Keratoconus – Europe, 2015
National Eye Institute, www.nei.nih.gov
medical-dictionary.thefreedictionary.com
Keratoconus pptx, Slideshare.com
Images and diagrams, google images search.