keratoprosthesis, kpro

1. KERATOPROSTHESIS
Presented by- Dr samarth mishra

2. Keratoprosthesis=artificial corneaKeratoprosthesis=artificial cornea
(kerato=cornea; prosthesis=artificial(kerato=cornea; prosthesis=artificial
substitute)substitute)
 The idea of artificial cornea was first proposed in
1789 by French ophthalmologist Guillaume Pellier
de Quengsy.
 The first reported human KPro surgery with a
quartz crystal implant was performed by Nussbaum
in 1855
 1950- Stone & Herbert – noted PMMA(poly methyl
methacrylate) splinters embedded in corneas of
pilot of World War II were well tolerated.

3. KERATOPROSTHESISKERATOPROSTHESIS
 Keratoprosthesis is a surgical procedure where a severely damaged
or diseased cornea is replaced with an artificial cornea.
 Keratoprotheses are made of clear plastic with excellent tissue
tolerance and optical properties. They vary in design, size and in the
implantation techniques.
 Keratoprosthesis restores sight – eye with damaged cornea by
means of a special tube that acts as a “periscope’’ from the eye to
outside world.
 Keratoprosthesis extend both inside the eye and outside into the
environment.
 It provides a tunnel vision.
 Extent of visual field increases with increase in diameter and
decreases with increasing length of the optical cylinder.

4. DESIGN & MATERIALSDESIGN & MATERIALS
 Keratoprosthesis –consists of an optical cylinder & a
supporting flange.
 Devices usually consist of a porous outer skirt element
joined to rigid polymethylmethacrylate lens.
 Materials used for optical cylinder-
1. PMMA(choyce & boston keratoprosthesis)
2. Dacron( pintucci keratoprosthesis)
3. Polycarbonate(champagne cork keratoprosthesis )
4. Hydroxy-apatite ( leon – barraquer Kpro)
5. Hydrogel( alpha cor keratoprosthesis) &
6. Polyurathane ( seoul keratoprosthesi)
 PMMA – most widely used material for optical
cylinder & never reported as a cause of failure.

5. SUPPORTING FLANGE made up of :SUPPORTING FLANGE made up of :
1. METHACRYLATE
2. TEFLON
3. DACRON MESH
4. POLYCARBONATE
5. TOOTH & BONE( OSTEO-ODONTO KPRO)
6. CARTILAGE(CHONDRO KPRO) OR
7. NAIL ( ONYCHO KPRO)

6. CLASSIFICATION OFCLASSIFICATION OF
KERATOPROSTHESIS DESIGNS:KERATOPROSTHESIS DESIGNS:
 NON PENETRATING ( INTRALAMELLAR )
 PENETRATING
 ANTERIOR
 POSTERIOR
 PERFORATING
 INTRALAMELLAR
 ANTERIOR
 Cardona through and through keratoprosthesis
 Ceramic keratoprosthesis
 Dohlman keratoprosthesis
 Osteo odonto keratoprosthesis
 Boston keratoprosthesis
 Champagne cork keratoprosthesis
 POSTERIOR
 Nut and Bolt keratoprosthesis

8. Keratoprosthesis
suitable for severe
dry eye with absent
tear function-
Osteo odonto
keratoprosthesis
Boston
keratoprosthesis
type II
Keratoprosthesis
indicated in eyes with
some residual tear
function are
classified as wet
eyes-
Champagne cork
Pintussi
Boston type I
Alpha cor
keratoprosthesis

10. Keratoprosthesi can be divided into temporary andKeratoprosthesi can be divided into temporary and
permanent depending on indicationpermanent depending on indication
Temporary device used intra operatively to aid in
visualization and removed following surgery.
 Indication include
 Severe ocular trauma for anterior & posterior segment
reconstruction
 Cataract extraction
 Modified triple procedure
 Vitreo retinal surgery in case of corneal opacity or ocular
trauma
 Combined PK &vitreoretinal surgery
 Ex- Eckardts keratoprosthesis, Landers Foulk & Landers
wide field lenses
Permanent keratoprosthesis- used to treat
patients with severe corneal disease where corneal
transplantation is inappropriate or has repeatedly failed.

11. INDICATIONS &INDICATIONS &
CONTRAINDICATIONSCONTRAINDICATIONS
Keratoprosthesis indicated in patients with bilateral corneal
blindness who have little or no chance of success with a
standard corneal graft.
Indicated in medical conditions like
Multiple graft failure
Graft failure with chronic edema
Corneal dystrophy
 Stevens-Johnson syndrome
 Ocular cicatricial pemphigoid
 Ocular burns (acid and alkali, thermal)
 and other conditions with poor prognosis with traditional PKP
Procedure of last resort
- to give at least navigational vision
- not done if BVA both eyes > or= CF

12. Indications:Indications:
Lacrimal choristoma
Failed corneal graft HZO/ neurotrophic keratopathy

13. STEVEN JOHNSONS SYNDROMES
Vascularized cornea
Central KPro in a patient with Acid burns
8yrs post-op VA 6/36

14. Contraindications
• Patients who are happy and managing with their level of
vision
•children under the age of 17,
• eyes that have no perception of light,
•evidence of phthisis,
•advanced glaucoma or
• irreparable retinal detachment should be excluded.
Suitable candidates have to understand that the surgery can
be prolonged—they may require multiple procedures—and
that there is a significant risk of serious complications
including loss of the eye.
The patient must be able to commit to life-long follow-up, and
not have unreasonable expectations of outcome and
cosmesis.

15. Preoperative assessmentPreoperative assessment
Eye undergoing keratoprosthesis surgery should
be free from initial insult of injury,physical
/chemical , active inflammation or infection.
Intraocular pressure should be adequately
controlled with no evidence of glaucomatous
damage to optic nerve head.
A good visual potential must be elicited with aid
of light projection, pupillary responses,
ultrasonography of posterior segment &
electrodiagnostic tests.

16. The commonly used ones are
BOSTON KPRO(TYPE 1 AND 2)
The Boston Type I Kpro is the most widely used device.
The Boston Type II Kpro may be indicated in patients
with severe ocular surface disease, poor ability to maintain
a moist ocular surface, and forniceal foreshortening with
inability to wear a contact lens
ALPHA-COR KPRO
AlphaCor Kpro is indicated in patients with failed grafts
due to corneal allograft rejection
OSTEO-ODONTO KPRO(OOKP)
OOKP like theBoston Type II Kpro, is reserved for end-
stage ocular surface
disease as a last resort

17. BOSTON KERATOPROSTHESISBOSTON KERATOPROSTHESIS
Boston Keratoprosthesis is the innovation
and design of Professor Claes H. Dohlman
FDA approval 1992
types 1 and 2
made from poly methyl methacrylate
(PMMA).
Most commonly used type 1

18. 2 Types
◦ Type 1:- More
commonly used.
Used in eyes that
have sufficient
wetting function to
maintain the corneal
tissue in which the
Kpro is placed.
◦ Type 2:- Used in
very dry eye with
minimal or no tear
production.
Boston Keratoprosthesis TypesBoston Keratoprosthesis Types

19. PartsParts
collar button design
 There is a front plate and
back plate sandwiching a
fresh donor corneal graft
Titanium locking ring is
used to secure the front And
back plates and corneal
complex to prevent Any
Inadvertent Unscrewing of
the complex.

20. Type 1Type 1
The typical anterior surface power of this device is 43–44
dioptres.
Aphakic eyes require a variety of powers depending on
the axial length

21. Type 2Type 2
The type 2 device is of a similar design,
with an added anterior cylinder that
protrudes through a permanently closed
upper eyelid, and is used in end-stage dry
eye
Back plates holes are important to allow
the nutrients to reach the graft
keratocytes from the aqueous

22. surgerysurgery
Superficial keratectomy of 8.5 mm of
donor cornea then a 3mm central punch
done
The donor button is then placed over
the stem of the front plate and the back
plate is slid into place on top of this
without screwing or turning.
 A titanium locking ring is then pushed
onto the remaining exposed stem until
an audible snap is heard

23. The recipient cornea is then trephined as
for conventional PKP (trephine diameter
0.5 mm less than donor trephine size).
The donor graft with the KPro is then
sutured in place with interrupted 10–0
nylon, using the same technique as a
standard PKP.
Surgery usually concludes with the
intracameral injection of 0.4 mg
dexamethasone
Conclusion with the application of a soft
contact lens
Post op steroid E/D ,antibiotic E/D used
Post op F/U at 1,2,4 wks,then monthly
Each visit IOP and VA noted and soft
contact lens changed

25.  Finally, a soft contact lens , plano power, is placed as
a bandage lens.
 All patients received lifelong prophylactic antibiotics:
moxifloxacin 0.5% , Vacomycin fortified drops
(25mg/ml) qid, Prednisolone Acetate 1% and Tears
Naturale Free .

27. OSTEO-ODONTO KPRO (OOKP)OSTEO-ODONTO KPRO (OOKP)
Osteo-odonto-keratoprosthesis
(OOKP) (also known as "tooth in eye"
procedure.
It includes removal of a tooth from the
patient or a donor. After this, a lamina of
tissue cut from the tooth is drilled and the
hole is fitted with optics. The lamina is
grown in the patients' cheek for a period
of months and then is implanted upon the
eye

28. MODIFIED OSTEO ODONTOMODIFIED OSTEO ODONTO
KPRO(MOOKP)KPRO(MOOKP)
The OOKP was first described by Strampelli in
1963
Later modified (MOOKP) by falcinelli and coll
It uses the patient’s own tooth root and
surrounding alveolar bone to support a centrally
cemented optical cylinder.
Multi staged procedure, sx in mouth and eye
PRINCIPLE
use of a wide single rooted tooth with surrounding
alveolar bone acts as carrier for a PMMA optical
cylinder, which is covered by buccal mucous
membrane,

31. Pre op assesmentPre op assesment
detailed history
Previous surgical interventions
An inaccurate projection of rays (PR) is not
a contraindication
Intraocular pressure is usually assessed by
digital tonometry
 Oral assessment includes assessment of
oral and dental hygiene and state of buccal
mucosa.
spiral CT scan of canines is carried out for
selection of a suitable tooth with the
assistance of an oromaxillofacial surgeon

32. MethodsMethods
In contrast to classic
OOKP, Our MOOKP
consists of 3 stages.
The first stage involves
the removal of iris and
lens, as well as the
preparation of the osteo-
dental lamina complex.

33. MethodsMethods
The second stage
involves the
preparation of
buccal mucosal
surface
Third stage
involves
implantation of
complex.

34. STAGE 1A
superficial keratectomy
fibrovascular pannus removal
intracapsular cataract extraction
anterior vitrectomy
total iridectomy
Complete removal of these structures is
done to reduce the possibility of
postoperative glaucoma and formation of
retroprosthetic membranes.

35. STAGE 1B
done usually 6 weeks after stage IA
full thickness mucous membrane graft (MMG) harvested from
the buccal mucosa.
The extent of MMG should be extend from upper to lower
fornix and measures around 3-4 cm in diameter.
MMG is sutured over damaged cornea at insertion of 4 recti
muscles and sclera In four quadrnts with 6.0 vicryl
It has stem cells,high proliferating Capacity and adapted to high
Bacterial load

36. STAGE 1C
Involves preparation of the osteo dental acrylic Lamina
(ODAL)
A single rooted tooth, preferably the upper canine is chosen
for preparation of the lamina.
The tooth with the surrounding alveolar bone is extracted.
Then sliced sagitally and Central hole is drilled
customized PMMA optical cylinder is cemented with acrylic
resin
ODAL is then placed in the subcutaneous pouch in the orbito
zygomatic area for next 3 months to develop vascularization
and to promote the growth of connective tissue.

37. STAGE 2
This is performed 3 months after stage IB+IC
ODAL is dissected off from the subcutaneous pouch and
examined for its integrity prior to proceeding with ocular surgery
The central cornea is trephined according to the posterior
diameter of the cylinder.
ODAL is placed with the cylinder centered over the corneal
trephination and sutured.
The MMG is finally reflected back on the lamina with a central
trephination through which the anterior cylinder protrudes out

38. POST OP MANAGEMENT
•Perioperatively, systemic and topical
antibiotics are administered.
•Systemic steroids and antiglaucoma
medication are also prescribed
Visual acuity, refraction, digital tonometry,
fundus, optic nerve status and visual fields
should be checked at each follow up.
The health of the mucous
membrane,protrusion and stability of the
optic cylinder should be looked for.

39. ALPHA COR KPROALPHA COR KPRO
The AlphaCor developed from the Chirila Kpro at
the Lions Eye Institute in Western Australia, first
implanted in human eyes in 1998 and receiving FDA
approval in 2003.
Manufactured from a single biocompatible polymer,
poly hydroxyethyl methacrylate (pHEMA)
two zones, a clear central optical core and an
opaque spongy skirt, made by polymerizing
the pHEMA under conditions of differing water
content
Interpenetrating polymer network (IPN) –
junction between the skirt and central optic
and is a permanent bond
Refractive Power close to that of human cornea .

40. ALPHA-COR KERATOPROSTHESISALPHA-COR KERATOPROSTHESIS
FDA-approved type of synthetic cornea
measuring 7.0 mm in diameter and
0.5 mm in thickness.
main advantages of synthetic corneas are
that they are biocompatible, and the
network between the parts and the device
prevents complications that could arise at
their interface.

42. PRINCIPLE
The ability of the outer skirt to be colonized by
invading keratocytes resulting in integration of
the device with surrounding tissues
INDICATIONS
Patients should have adequate tear production
as assessed by the unstimulated Schirmer test
with a value of at least 50% of normal
VA from <6/60 to light perception
previous failed grafts with a poor chance with
further PKP
Functioning retina
absence of evidence of advanced
glaucomatous optic neuropathy or well-
controlled glaucoma on treatment.

43. Surgical procedure-- 2 stageSurgical procedure-- 2 stage
procedureprocedure
STAGE 1
•360° conjunctival peritomy
debridement of the corneal epithelium
superior half of the cornea is dissected into two
layers, superficial and deep, each of about 50%
thickness, through a superior paralimbal 180°
incision
extended to form a pocket in the inferior cornea
superficial corneal flap is then reflected inferiorly to
expose the deep cornea, to allow trephination of the
central posterior lamella with a 3.5 mm disposable
trephine to enter the anterior chamber
The AlphaCor is placed between the two layers
within the pocket, centred over the posterior
lamellar opening
The superficial flap is then replaced and sutured at
the limbus with interrupted 10/0 nylon.

44. STAGE 2
•2 months after Stage I
•tissues superficial to the AlphaCor optic (anterior corneal
lamella) are removed to expose the optical zone.

45.  Following trephination and removal of the host
cornea, manual extracapsular cataract extraction
is performed via an open-sky technique with
placement of a plano intraocular lens.
COMBINED KERATOPROSTHESIS PLACEMENT,
CATARACT EXTRACTION, AND IOL IMPLANTATION

46. The pre-assembled keratoprosthesis is
sutured into position with interrupted bites
using 9.0 nylon suture.

47. SINGH-WORST KPROSINGH-WORST KPRO
 Designed and developed in collaboration
with Dr. Jan Worst in Netherlands and Dr.
Daljit Singh in India.
 Champagne-Cork Design for better stability.
 one piece polycarbonate device
 anterior surface has a diameter of 6.0mm
 Shaft end diameter 4.5mm. Neck diameter
3.0 mm.
 The flange has 8 equidistant holes near the
margin.
 Anticonical shape –creates a valve on the
cornea
 Steel suture fixation on equatorial sclera
preventing extrusion.

48. Stanford Keratoprosthesis :-
◦ Kpro is based on a mechanically enhanced
Hydrogel called Duoptix
◦ It supports the growth of epithelial cells.
◦ Surrounding the optic is a microperforated rim
designed to promote peripheral tissue
integration
Collagen Based Keratoprosthesis
◦ Designed to mimic the extra cellular Matrix of
corneal stroma
Modified Keratoprosthesis Biomaterials
with bio active factors
Recent AdvancesRecent Advances

49. COMPLICATIONSCOMPLICATIONS
MELTS AND EXTRUSION
INFECTIOUS ENDOPHTHALMITIS
GLAUCOMA
RETRO PROSTHETIC MEMBRANES
RETINAL DETACHMENT
OTHERS

50. MELTS AND EXTRUSIONMELTS AND EXTRUSION
Melts tends to occur at the base of Boston
kpro
USG and anterior segment OCT are helpful in
detection and f/u of corneal thinning around
kpro
Any leak on siedels test, USG to be done to
see choroidal effusion
If melts are seen then replace the whole thing
with fresh graft and put new kpro’
In MOOKP, resorption of buccal mucosa can
occur,new graft can be placed
Resoprtion of osteo odonto lamina can
occur,serial CT scan yearly
If much resorption of dentine has occurred
entire thing should be replaced

52. INFECTIOUSINFECTIOUS
ENDOPHTHALMITISENDOPHTHALMITIS
Dreadful complication
following kpro sx
Often evidence of leak
seen
Rx includes leak
repair,i/vit tap,injection
of antibiotics and topical
antibiotics
Fungal infection
suspected change
contact lens and give
topical amphotericin and
systemic anti fungals
required

53. GLAUCOMAGLAUCOMA
Single most serious complication following
sx leading to irreversible loss of vn
D/T chronic low grade
inflamman,progessive angle
closure,anterior displacement of iris have
been implicated
Topical rx is effective in pts with boston
type 1 kpro
systemic rx can be used with boston type
2 and MOOKP
Tube shunts and endoscopic
cyclophotocoagulation have been
succesfully used with all types of kpros

55. RETRO PROSTHETIC MEMBRANESRETRO PROSTHETIC MEMBRANES
 Most commonly reported
 Occurs in 25-64% of pts in 1 yr follow up
 These fibrous membranes originate from activated host
stromal cornea cells that migrate through gaps in the
posterior graft–host junction
 RPM formation seems to be more prevalent in individual
with chronic inflammation such as autoimmune diseases
and uveitis
 Development of titanic back plates have reduced incidence

56. Treatment
Nd yag capsultomy following by steroids in 90% cases
If membrane thick,leathery and vascularised,sx
management
For boston kpro vit+membranectomy can be performed
However removal of prosthesis and repacement with new
one is preferred

57. RETINAL DETACHMENTRETINAL DETACHMENT
Most common posterior segment complication
with an incidence of 16.9 %
Surgical rx with buckle or vitrectomy is
performed
achievement of anatomic success is limited by
the presence of chronic retinal scarring or
proliferative vitreo retinopathy (PVR) and visual
outcomes tend to be worse in these cases
Choroidal detachments can also develop in eyes
with KPro, in as many as 17 % of patients

58. MOOKP

59. Thank youThank you