CORNEAL AND REFRACTIVE SURGERY

1. CORNEAL AND REFRACTIVE
SURGERY

2. PRESENTERS
• JOHN OPONDO
• DAVID ONYANGO
• BEVERLINE KHAVERE
• MICHELLE WANJIRU

3. KERATOPLASTY
• Replacement of diseased host corneal tissue by healthy donor
cornea
• Partial thickness or full thickness

4. INDICATIONS
• Optical keratoplasty- improve vision. They include keratoconus,
scarring, corneal dystrophies, pseudophakic bullous keratopathy and
corneal degeneration
• Tectonic graft -restore or preserve corneal integrity in eyes
• Therapeutic corneal transplantation – in eyes unresponsive to
antimicrobial therapy
• Cosmetic grafting- to improve the appearance of the eye

5. KERATOPLASTY
Optical penetrating keratoplasty for
macular
corneal dystrophy;
tectonic lamellar patch graft for
descemetocoele;
penetrating keratoplasty for
pseudomonas keratitis

6. DONOR TISSUE
• Removed within 12-24 hours of death
• Age-match donors and recipients
• Stored in coordinating eye banks for pre-release evaluation
• Preserved in hypothermic storage(7-10 days) and organ
culture(4 wks)

7. CONTRAINDICATIONS TO TISSUE
DONATION
• Death from unknown causes
• Certain systemic infections
• Prior high risk behavior for HIV and hepatitis
• Sex with someone who has engaged in high risk behavior(last 12months)
• Infectious and possibly infectious disease of the CNS
• Receipt of a transplanted organ
• Receipt of human pituitary-derived GH
• Brain or spinal surgery before 1992
• Most hematological malignancies
• Ocular disease

8. RECIPIENT PROGNOSTIC FACTORS
• Severe stromal vascularization
• Abnormalities of the eyelids
• Conjunctival inflammation
• Tear film dysfunction
• Anterior synechiae
• Uncontrolled glaucoma
• Uveitis

9. PENETRATING KERATOPLASTY
• Key surgical points
Graft size 7.5mm
Donor button >0.25mm larger than host site
Preparation should precede excision of host tissue
Manual/automated trephination is used
Secured with interrupted or continuous suture techniques

10. Excision of host tissue.

11. POSTOPERATIVE MANAGEMENT
• Topical steroids- decrease risk of immunological graft rejection
• Other immunosuppressants- high risk patients
• Cycloplegics
• Oral acyclovir- pre-existing herpes simplex keratitis
• Monitoring of IOP- non-applanation tonometry
• Removal of sutures – after 12-18 months

12. POSTOPERATIVE COMPLICATIONS
EARLY
Wound leak
Uveitis
Microbial keratitis
Endophthalmitis
Rejection
Microbial
keratitis

13. POSTOPERATIVE COMPLICATIONS
EARLY
Loose continuous suture with
probable infection and rejection
traumatic graft rupture and
extrusion of intraocular lens
implant
microbial keratitis

14. POST OPERATIVE COMPLICATIONS
LATE
 Astigmatism
 Recurrence of underlying disease
 Late wound dehiscence
 Retro corneal membrane formation
 Glaucoma
 Rejection
 Failure without rejection

15. CORNEAL GRAFT REJECTION
PATHOGENESIS
Predisposing factors
• Eccentric or larger grafts
• Glaucoma
• Previous keratoplasty

16. SYMPTOMS
• Blurred vison
• Redness
• Photophobia
• Pain
SIGNS
• Ciliary injection
• Epithelial rejection- elevated line of
abnormal epithelium
• Subepithelial rejection-subepithelial
infiltrates
• Stromal rejection
• Endothelial rejection –linear pattern of
keratic precipitates
• Stromal edema

17. CORNEAL GRAFT REJECTION
elevated epithelial line in epithelial
rejection
Krachmer spots endothelial rejection with
Khodadoust line

18. DIFFERENTIAL DIAGNOSIS
• Graft failure
• Infective keratitis
• Uveitis
• Sterile suture reaction
• Raised IOP
• Epithelial ingrowth

19. MANAGEMENT
• Preservative free topical steroids
• Topical cycloplegic
• Topical cyclosporin
• Systemic steroids
• Subconjunctival steroid injection
• Other systemic immunosuppressants

20. SUPERFICIAL LAMELLAR KERATOPLASTY
• Partial-thickness excision of the corneal epithelium and stroma
• Endothelium and deep stroma are left behind
Indication
• Opacification of the superficial 1/3 corneal stroma
• Marginal corneal thinning or infiltration
• Localized thinning or descemetocoele

21. DEEP ANTERIOR LAMELLAR KERATOPLASTY
(DALK)
• Corneal tissue is removes almost to the level
of Descemet membrane
• Decreased risk of rejection-endothelium is
not transplanted
Indications
• Disease involving anterior 95% of cornel
thickness with absence of breaks/scars in
Descemet’s membrane
• Chronic inflammatory disease

22. DEEP ANTERIOR LAMELLAR KERATOPLASTY
Advantages
• No risk of endothelial
rejection
• Less astigmatism and
stronger globe
• Increased availability of graft
material
Disadvantages
• Difficult and time consuming
• Interface haze may limit best
final VA

23. DEEP ANTERIOR LAMELLAR KERATOPLASTY
• Post operative management
Similar to penetrating keratoplasty except lower intensity topical
steroids are needed and sutures are removed after 6 months

24. ENDOTHELIAL KERATOPLASTY
• Removal only of diseased endothelium along with Descemet
membrane through corneoscleral or corneal incision.
• Folded donor tissue introduced through the same small(2.8-
5.0mm) incision
• DSAEK- uses an automated microkeratome to prepare door
tissue .Small posterior stromal thickness transplanted along
with DM and endothelium
• DMEK-only the DM and endothelium transplanted
• Indications - endothelial disease

25. ENDOTHELIAL KERATOPLASTY
Advantages
• Little refractive change and
more intact globe
• Faster visual rehabilitation
• Suturing is minimized
Disadvantages
• Significant learning
curve
• Specialized equipment
required
• Endothelial rejection

26. LIMBAL STEM GRAFTING
Techniques include:
• Transplantation of a limbal area of limited
size
• Complete limbal transplantation
• Ex vivo expansion by culture with
subsequent transplantation

27. KERATOPROSTHESES
• Artificial corneal implants use in
patients unsuitable for
keratoplasty
• Odontokeratoprostheses-
patient’s own tooth root and
alveolar bone and covered with a
buccal mucous membrane graft
• Surgery is difficult and time
consuming, done in 2 stages 2-4
months apart

28. KERATOPROSTHESES

29. KERATOPROSTHESES
Indications
• Bilateral blindness- severe but
inactive anterior segment
disease
• VA of counting finger or less in
better eye
• Intact optic nerve and retinal
function
• High patient motivation
Complications
• Glaucoma
• Retroprosthesis membrane
formation
• Tilting or extrusion
• Endophthalmitis

30. KERATOPROSTHESES
Results
• Approx. 80% of patients achieve VA between counting fingers
and 6/12
• Poor outcome associated with pre-existing optic nerve or
retinal dysfunction

31. REFRACTIVE PROCEDURES
• Procedures aimed at changing the refraction of the eye by
altering the cornea or lens

32. CORRECTION OF MYOPIA
• Surface ablation procedures- correct low-moderate degrees of
myopia
• Laser in situ keratomileusis (LASIK)- moderate-high myopia
depending on corneal thickness
• Refractive lenticule extraction- correction of myopia and
myopic astigmatism
• Clear lens exchange- very good visual result but small risk of
complications of cataract surgery

33. CORRECTION OF MYOPIA
• Iris clip (lobster claw)-implant attached to iris
Complications
 Subluxation
 Oval pupil
 Endothelial cell loss
 Cataract
 Pupillary –block glaucoma
 Retina detachment

34. CORRECTION OF MYOPIA
• Phakic posterior chamber implant( ICL)- inserted behind the iris
and in front of the lens, supported in the ciliary sulcus
Material derived from collagen with a power of -3D to -20.50D
Complications include uveitis, pupillary block, endothelial cell
loss, cataract formation and retinal detachment
• Radial keratotomy

35. CORRECTION OF MYOPIA
Anterior chamber iris claw implant
with anterior
iris attachment at 3 and 9 o’clock
inferior subluxation
with resultant inferior endothelial
decompensation –
note also an iridectomy to prevent pupillary
block
emplacement of a posterior chamber
phakic implant
between the iris and anterior lens
surface

36. CORRECTION OF HYPERMETROPIA
• Surface ablation procedures- low degrees
• LASIK – up to 4D
• Conductive keratoplasty (CK)- application of
radiofrequency energy to the corneal stroma
,thermally induced stromal shrinkage is
accompanied by increase in central corneal
curvature
• Laser thermal keratoplasty- holmium laser can
correct low hyperopia
• Clear lens extraction
• Phakic lens implants

37. CORRECTION OF ASTIGMATISM
• Limbal relaxing incisions/ arcuate keratotomy-making paired
arcuate incisions on opposite sides of cornea in the axis of the
correcting plus cylinder
• PRK and LASEK – up to 3D
• LASIK- up to 5D
• Lens surgery- toric intraocular implant
• Conductive keratoplasty

38. Arcuate
Keratotomies ; toric intraocular implant in site
markings incorporated in the lens (arrows)
facilitate correct
orientation

39. CORRECTION OF PRESBYOPIA
• Lens extraction- to treat cataract of
refractive purposes
Include :
• Clear lens exchange(CLE)
• Refractive lens exchange(RLE)
• Presbyopic lens exchange(PreLEx)

40. CORRECTION OF PRESBYOPIA
Small aperture inlay Small aperture in lay Partial extruded refractive inlay

41. LASER REFRACTIVE PROCEDURES
Laser In Situ Keratomileusis
• The excimer lase is used to reshape corneal stroma exposed by
the creation of a superficial flap
• Myopia corrected by central ablative flattening
• Hyperopia by ablation of the periphery so that the center
becomes steeper
• Generally used to treat higher refractive errors:
 Hypermetropia- up to 4D
 Astigmatism –up to 5D
 Myopia –up to 12D

42. LASIK
Elevating the flap Wrinkling of the flap Sub-epithelial haze

43. LASIK
Epithelial in growth Diffuse lamellar keratiitis Bacterial keratitis

44. LASIK
Technique
• Suction ring centered on the cornea is applied to the globe-
raises IOP
• Ring stabilizes the eye and provides the guide track for a
mechanical microkeratome
• The flap is reflected and the bed reshaped then flap
repositioning

45. LASIK
Intraoperative complications
• Buttonholing of the flap
• Flap amputation
• Incomplete or irregular flap creation
• Penetration into the anterior chamber

46. LASIK
Postoperative complications
• Tear instability
• Wrinkling, distortion or dislocation of the flap
• Subepithelial haze
• Persistent epithelial defects
• Epithelial ingrowth under the flap
• Diffuse lamellar keratitis
• Bacterial keratitis
• Corneal ectasia

47. SURFACE ABLATION PROCEDURES
• Photorefractive keratectomy(PRK) employs excimer laser ablation to reshape
the cornea
• Corrects myopia- up to 6D , astigmatism- around 3D and low-moderate
hyperopia
• Main disadvantage as compared to LASIK- lower degrees of refractive error
correctable and slower epithelial healing
• Lower risk of serious complications than in LASIK
• Suitable for patients renders ineligible for LASIK due to low corneal
thickness
• Other indications include epithelial basement membrane disease, prior
corneal transplantation or radial keratotomy and large pupil size

48. SURFACE ABLATION PROCEDURES
Technique
• Corneal epithelium is removed using a sponge, an automated
brush and alcohol
• Ablation of the Bowman’s layer and anterior stroma, taking 30-
20 sec
• Epithelium heals within 48- 72 hrs. bandage contact lens is
used to minimized discomfort

49. SURFACE ABLATION
Corneal ablation during photorefractive
keratectomy RK or advanced surface (laser)-
ASA/ASLA

50. SURFACE ABLATION TECHNIQUES
Complications
• Slowly healing epithelial defects
• Corneal haze with blurring and haloes
• Poor night vision
• Regression of refractive correction
Uncommon problems
• Decentered ablation
• Scarring
• Abnormal epithelial healing
• Irregular astigmatism
• Hypoesthesia
• Sterile infiltrates
• Infection
• Acute corneal necrosis

51. SURFACE ABLATION TECHNIQUES
Variations of PRK
• LASEK- Laser Epithelial Keratomileusis or Laser –assisted
subepithelial keratectomy
• Epi-LASIK-Epipolis or epithelial LASIK
• Modified PRK
• ASLA OR ASA- Advanced surface ablation
• Trans-PRK- transepithelial PRK

52. REFRACTIVE LENTICULE EXTRACTION
• ReLex is a relatively long technique that uses a femtosecond
laser to cut a lens-shaped piece of corneal tissue with the
intact cornea
• Then removed via a LASIK-style flap or using a minimally
invasive 4mm incision
• Advantages include:
Less marked biochemical and neurological corneal disturbance
than LASIK
Surface disturbance is minimal in comparison to surface
ablation procedures

53. REFRACTIVE LENTICULE EXTRACTION