3. INTRODUCTION
• CONICAL CORNEA
• Keratoconus a noninflammatory ectasia of axial part of cornea
• Described first by Burchard Mauchart
• Usually starts at puberty and progresses slowly
4. AETIOLOGY*
• Congenital weakness of cornea, though it manifests only after puberty
• Secondarily following trauma
• Heredity
• Eye rubbing
• Endocrine anomaly.
• With vernal keratoconjunctivitis
• Down syndrome
5. PATHOPHYSIOLOGY
• Biomechanical hypothesis proposes keratoconus to result from interlamellar and
interfibrillar slippage of collagen within stroma*
• Progressive thinning and ectasia as a result of
-defective synthesis of mucopolysaccharide
and collagen tissue
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11. CLINICAL FEATURES
• Although can present in any age group, it more commonly affects patients in
their late teens or early twenties
• The condition almost always progressive but the rate of progression and
severity is variable
• Tends to progress more rapidly in young patients
12. SYMPTOMS
• Defective vision due to
- progressive myopia
- irregular astigmatism
which does not improve fully on glasses
13. SIGNS
• On ocular examination - Window reflex is distorted.
- MUNSON’S SIGN seen
• Slit lamp examination - thinning and ectasia of central cornea
- opacity at the apex
- Fleischer’s ring at base of cone
- folds in Descemet’s and bowman’s membranes
- very fine, deep stromal striae (VOGT LINES) which
disappear with external pressure
14. • Retinoscopy - SCISSOR REFLEX
- irregular astigmatism
• Distant direct ophthalmoscopy – annular dark shadow is seen which separates the
central and peripheral areas of cornea (OIL DROPLET REFLEX)
• Keratometry – keratometric values are increased
• Corneal topography- most sensitive method of detection – FORME FRUSTE refers
to earliest subclinical form of keratoconus detected
16. COMPLICATIONS
• Acute hydrops – due to rupture of descemts membrane.
- characterized by sudden development of corneal edema
- marked defective vision, pain, photophobia and lacrimation
17. Nipple cone - (<5 mm)
Oval cone – (5 to 6 mm)
Globus cone – (>6mm)
Cone type
& position
CLASSIFICATION
20. SPECTACLE CORRECTION
• The patient’s refractive error can often be successfully managed with spectacle in
the early stages
21. • Usually a rigid gas permeable contact lens improve vision in early cases
• In moderate cases, a specially designed scleral contact lens (ROSE-K) is useful
• INTACS, the intracorneal ring segment, are useful
• Corneal collagen cross linking with riboflavin and UV-A rays may slow the progression
• Keratoplasty required in later stages
-Deep lamellar keratoplasty (DALK)
-Penetrating keratoplasty (PK)
27. CORNEAL COLLAGEN CROSS LINKING WITH
RIBOFLAVIN
• This treatment have been shown to slow down or arrest the progression of
keratoconus and in some cases reverse it
• The need to keratoplasty thus might be significantly reduced
• Clinical trials are continuing and the technique is definitely showing promise in
treating early cases
no one theory fully explains clinical findings
No direct evidence but the condition often first develops at the time of puberty and occasionally during pregnancy.
due to loss of cohesion between collagen fibrils and non collagenous matrix.
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Presenter’s level of expertise in the subject: Briefly state your credentials in this area, or explain why participants should listen to you.
small near centre less than 5mm in diameter
the most common type, apex of cone is displaced well below midline.
a large cone affecting nearly three quarter of corneal surface, more than 6mm in diameter
(based on keratometry)
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are surgically inserted through a a small radial incision into a track created within the central cornea stroma
collagen cross linking within the corneal stroma and so recovers some of its mechanical strength
-gold standard surgery for keratoconus patients with success rates of more than 90%
-keratoconic cornea is replaced by removing the central area of cornea and a full thickness donor corneal button is sutured in its place
-corneal trephines between 8-8.5mm are used
-second eye is not grafted until the first eye is successfully rehabilitated usually keeping an interval of 12 months.
a partial thickness corneal transplant
-The host cornea is removed upto the depth of posterior stroma and a lamellar donor corneal button is sutured in place
technique requires less recovery time, and poses less chance for corneal graft rejection or failure.
-This technique is difficult and visual acuity is inferior to that of penetrating keratoplasty
In DALK the patients endothelium is retained giving additional structural integrity to post graft cornea. This technique requires less recovery time
