Keratoconus is a degenerative disease of the cornea characterized by thinning and cone-shaped deformation that leads to irregular astigmatism, typically manifesting between ages 16 and 30. Its causes are not fully understood but may involve factors like eye rubbing and hormonal changes, with diagnosis primarily through detailed examination and corneal topography. Management options range from spectacles and various types of contact lenses to surgical interventions like collagen cross-linking and keratoplasty for advanced cases.

1. ~ Kunjvihari Yadav
(Optometry intern at UPUMS, Saifai, Etawah, UP)

2. Introduction
 From Greek
Kerato= Cornea
Conus = Cone-shape
 Definition - keratoconus is a degenerative non-inflammatory
disease of the cornea where the central or paracentral cornea
undergoes progressive thinning , changing it from dome-shaped to
cone shape , causing irregular astigmatism.

4. Onset of keratoconus
 It can be anywhere between the ages of 8 and 45.
 In the majority, it becomes apparent between the ages of 16 and 30
years .
 It affects male and female equally .
 KC is present in both eyes in over 90% of cases.
 Onset is not always at the same time or to the same magnitude .
 KC is has been associated with conditions such as-
• Hay fever
• Asthma
• Eczema
• Down’s syndrome
• Marfan’s syndrome etc.

5. Etiology
 Still unknown.
 The incidence of KC reported to be 1 in 2000 people
 Heredity- there is less than one in ten chances that a blood relative
of keratoconic patient will have KC.
 Eye rubbing- especially children due to some diseases as vernal
keratoconjunctivitis . So corneal curvature will be changed . Eye
rubbing among keratoconic patient has been reported 66% to 73% .
 Hormonal change - that KC is often first develops around puberty.
Or advances during pregnancy.
 Contact lens wearer- uncorrect fitting.

6. Classifications
 Based on severity of curvature -
• Mild: <45.00D
• Moderate: 45.00D to 52.00D
• Advanced: 52.00D to 62.00D
• Severe: >62.00D
 Based on shape -
• Nipple cones: cone small size 5mm
• Oval cones: larger ellipsoid 5-6mm
• Globus cones: largest>6mm, may involve over 75% of
cornea

7. Nipple cone Oval cone Globus cone
• Diameter: <5mm
• Cone: lies in centre towards
inferior nasal quadrant
• Easiest to fit with CL
• Diameter: >5mm
• Cone: displaced
inferiorly
• More difficult to fit
with CL
• Diameter: >6mm
• Cone: steepening
• 75% affected cornea
• Most difficult to fit with CL

9. The classic signs of KC
Corneal nerves:
• More prominent then in
normal eye.
Vogt’s striae:
• Fine vertical line in the
stroma and Descemet’s
membrane.
• disappear temporarily on
digital pressure.
Fleischer’s ring:
• Iron pigment ring forms
the base.
• May be partial or
complete.

10. The classic signs of KC
Corneal thinning:
• Represents an actual
reduction in the number
of stromal lamellae.
Munson’s sign:
• Ectasic protrusion of the
cornea on down gaze
produces a V-shaped
conformation of the lower
lid.
Rizzuti sign:
• Lateral illumination of the
cornea produces a steeply
focused beam of light near
the limbus.

11. Corneal scarring:
• Sub-epithelial corneal scarring.
• Not generally seen early.
• May occurs as keratoconus
progresses because of ruptures in
bowman’s membrane which is then
filled with connective tissue.
Corneal hydrops:
• Occurs generally in advanced cases,
when Descemet’s membrane
rupture, aqueous flows into the
cornea and reseals.

12. Diagnosis
 Diagnosing keratoconus in its early
stages is more difficult . It requires a
through history and examination .
• Visual acuity – Reduced visual acuity
due to oblique astigmatism.
• Retinoscopy – scissor reflex
• Keratometer- distorted mires
• Ophthalmoscopy – oil droplet
• Reduced intraocular pressure- due to
corneal thinning or reduced scleral
rigidity.

13. • The topography of keratoconus – the photokeratoscope or placido
disc can provide an overview of the cornea and can show the
relative steepness of the corneal area.
 Photokeratoscope with normal round curvature  Distorted pattern of the rings.

14. Nipple-Shaped Topography
Small near central ectasia, less than
5.0 mm in cord diameter .
May manifest as a small central ectasia
with moderate to high with-the-rule
corneal astigmatism.

15. Oval-Shaped Topography

16. Globus-Shaped Topography

17. Management of kc
 Spectacles-
• Mild keratoconus in early stage
can be corrected with spectacles.
• As the cornea steepens and
becomes more irregular , glasses
not capable of providing adequate
visual improvement.

18.  Contact lenses -
• Soft contact lenses.
• Rigid gas permeable lenses.
• Combined lens system-
1. Piggy back system
2. Hybrid lens system
• Fully keratonic designed lenses-
1. Rose k
2. Scleral and mini scleral lens

19.  soft contact Lenses -
• It is not better than spectacle lens but it works in piggy back system
.
• At very stage, this way work as equal to spectacle .
• But patient may not be satisfied with the level of vision he has even
though it is 6/6-
• Shadow effect of texts
• Ghosting of image
• Poor night vision
• Eye fatigue on prolong reading

20.  Rigid Gas Permeable Lenses -
• Cost effective , easily available ,
suitable for mild to moderate
keratoconus .
• Fitting: three point conventional
fitting philosophy.

21.  combined lens system -
 Piggy back system-
Rigid lens fitted over a hydrogel lens
increases comfort resulting in
adequate wearing time with good
vision .

22.  combined lens system -
 hybrid lens system –
One way to overcome the problems with piggyback lenses, yet have
the optics of a rigid lens with the comfort of a hydrogel , it is to fuse a
soft rim onto a hard central portion .

23. fully keratoconic designed lens -
• Rose K: • Scleral lenses

24.  Surgical intervention-
 Collagen cross-
linking (CXL or C3-
R):
It may slow or halt the
progression of
keratoconus by using a
photo-oxidative treatment
to increase the rigidity of
the corneal stroma .

25.  Keratoplasty
• For patients intolerant to contact lens and cases with scarring.
• Penetrating keratoplasty and Deep anterior lamellar keratoplasty can
be done .
Penetrating keratoplasty:
In this procedure , the central area
of the cornea is excised and a full-
thickness corneal button is sutured
into the recipient

26.  Lamellar keratoplasty:
A partial thickness portion of the cornea is excised and a partial
thickness donor corneal button is sutured into the recipient
transplant .

27.  Intacs: intrastromal corneal ring –
Two arc shaped segments of inert plastic are inserted into the
peripheral (outer) cornea.
These segments add volume to the thinned area .
This flattens the steep curvature and reduces the irregular shape.

28. STEPS IN KERATOCONUS TREATMENT
KERATOCONUS
PROGRESSIV
E
NON PROGRESSIVE
SPECTACLE
S
CONTACT
LENSES
CXL
CORNEAL SCLERAL
INTACT
S
CORNEAL
TRASPLANT
S
PHAKIC
IOLS
ACCELARAT
ED CXL
SURGICAL
OPTIONS
SCLERAL LENSES ARE THE BEST CHOICE FOR KERATOCONUS