Lamellar keratoplasty

keratoplasty, partial corneal transplantation, presentation

1. Lamellar Keratoplasty MODERATOR- DR SUNDEEP PRESENTER- DR AKSHAY NAYAK

2. DEFINITION The replacement of diseased cornea with autologus or heterologus cornea is called as keratoplasty . In most of the cases the donor cornea is taken from a deceased person. Either full thickness of the cornea or a part of it may be transplanted.

3. Introduction For over hundred years Penetrating keratoplasty has been the standard care for corneal diseases PK involves replacing a full thickness of diseased recipient’s cornea with that of a healthy donor cornea secured into place with 32,16 or 12 sutures Claesson et al studied 520 grafts, at 2 years after PK showed a visual acuity of upto 20/40 (6/12)

4. Layers Thickness(um) Composition Epithelium 50 Stratified Squamous Epithelium  Bowman’s Membrane 8-14 Compact layer of unorganised collagen fibres Stroma Stroma 500 Orderly arrangement of collagen lamellae with keratocytes   Descemet’s Membrane 10-12 Consists of basement membrane materials Endothelium 5  single layer of simple squamous epithelium

5. Types of keratoplasty Based on the thickness of the cornea transplanted, keratoplasty can be divided as: Penetrating keratoplasty - involved full thickness of the cornea. Lamellar keratoplasty - involves transplantation of a part. Anterior lamellar : SALK, MALK, DALK, TALK Posterior lamellar : DLEK, DMEK, DSAEK,DSEK

6. Donor tissue Removed as early as possible (6-12 hours of death). Corneas from infants (2 years and under) are rarely used -surgical, refractive and rejection problems. It should be stored under sterile conditions. Evaluation – medical history review and donor blood screening to exclude contraindications, and microscopic examination of the cornea including endothelial cell count determination

7. Corneal preservation Short-term storage (up to 2 days) -The whole globe is preserved at 4 C in a moist chamber. Intermediate storage (up to 2 weeks) - McCarey -Kaufman (MK) medium and various chondroitin sulfate enriched media such as optisol medium used. Long-term storage ( up to 35 days) -It is done by organ culture method.

8. Contraindications for donation of corneal tissue Absolute Rabies HIV , viral hepatitis, syphilis and active malaria . Septicaemia Prior high-risk behavior for HIV and hepatitis. infectious diseases of the CNS . Creutzfeldt -Jacob disease Relative Most hematological malignancies. Ocular disease such as inflammation and malignancies (e.g. retinoblastoma) and corneal refractive surgery . Death of unknown cause. Congenital rubella, tuberculosis

9. Why there is need for an alternative to PK?????

10. Because PKP induced astigmatism in range of 3 to 7 diopters Decline in endothelial cell count leading to graft failure Allograft rejection and endothelial decompensation were the major concerns Postoperative discomforts and wound healing time more Wound strength in lamellar graft superior Non penetrating surgery, it reduces the risk of intraocular complications like glaucoma, cataract, CME,RD, endophthalmitis Graft quality , endothelium count should be good in cases of PK compared to LK

11. LAMELLAR KERATOPLASTY Involves a partial thickness of the cornea that is transplanted only on the diseased portion. Less invasive procedure but involves finer surgical skill and more refined instrumentation.

12. History In 1824 Reisinger performed the first animal graft and coined the term ‘ Keratoplasty ’. The first successful lamellar keratoplasty was performed by Arthur Von Hippel at the end of 19th century. Jose Barraquer was the first to perform posterior lamellar keratoplasty in 1950

13. Anterior Lamellar Keratoplasty (ALK)  Removal and replacement of deformed or diseased anterior corneal tissue ( epithelium, Bowman’s layer, and stroma) Sparing the host Descemet’s membrane and endothelium 

14. Indications Indicated in corneas that have a healthy endothelium 1.Optical ALK is useful in Anterior stromal scars after infectious keratitis or trauma Complications after refractive surgery Dystrophies like epithelial and stromal dystrophy Salzmann nodular degenerations, spheroidal degeneration etc Post inflammatory:Trachomatous kerartopathy,healed superficial keratitis

15. Indications ( contd …) 2. Tectonic ALK is useful in Peripheral non inflammatory thinning Terrien’s marginal degeneration Pellucid marginal degeneration Peripheral ulcerative autoimmune keratitis - Mooren’s ulcer. Descematocoele 3. Combined indications include Keratoconus Pellucid marginal degeneration Iatrogenic keratoectasia after Refractive surgeries 4.therapeutic Infective keratitis limited to anterior corneal layers

16. Surgical Planning (Surgeon to ask themselves) Is the Endothelium Normal? What level does the pathology extend? Will leaving minimal posterior stroma affect visual outcome?

17. SALK should be used when the anterior 30--50% of the cornea is affected with pathology and is to be replaced with a similar amount of donor tissue. The main indications are superficial scars resulting from healed infections, including trachoma, trauma (post-laser or accidental), superficial corneal dystrophies and degenerations, or persistent epithelial defects

18. Surgical Techniques 1)DIRECT DISSECTION- Partial thickness(60-80%) trephination Corneal stromal dissection with crescent Partial thickness donor Suture Disadvantage – Unreliable depth of dissection Irregular Host Bed Interface haze

19. Melles Technique(closed dissection) To visualize the depth of lamellar dissection – Exchange aqueous with air- Create Air Endothelium interface – Act as convex mirror Specialised spatula –stromal pocket—inject visco —stroma over visco excised A black band is visualized in front of dissecting instrument, which represent twice the residual stroma Trephination A full-thickness donor button stripped off its DM is sutured in place. Good visual results have been reported with this technique. There is about a 14% chance of DM perforation.

20. ANWAR Big Bubble Technique

21. Surgical technique Anwar ‘BUBBLE’ TECHNIQUE The technique involves trephining the anterior host corneal surface with a Hessburg -Barron suction trephine to a depth of about 400 µm 25-gauge disposable needle inserted into the corneal stroma, Air is then injected to create a big bubble (Anwar’s technique) that will detach the deep stromal layers from the Descemet’s membrane. lamellar dissection and removal of the anterior stromal disk by crescent knife

22. Using a 30° superblade /15° lance tip, a small oblique incision is made in the corneal stromal surface, releasing air and collapsing the big bubble. The space between the Descemet’s membrane and the detached deep stroma is then filled with viscoelastic. Utilizing a divide-and-conquer technique with corneal microscissors , the remaining deep corneal stroma is excised to expose the smooth surface of the Descemet’s membrane

23. The donor cornea is then trephined with a Hessburg -Barron trephine, followed by staining of the endothelium with trypan blue. Descemet’s membrane and the donor endothelium are then removed using dry cellulose sponges and forceps. The donor cornea devoid of Descemet’s membrane and endothelium is then placed within the host corneal bed and sutured in place with 16 interrupted 10-0 nylon sutures.

24.   Viscoelastic Dissection Technique – Viscoelastics , namely sodium hyaluronate , were forced into a previously made stromal pocket using a 25-gauge blunt cannula to create a visco -bubble. This technique detaches the deeper stromal layer from the Descemet’s membrane, and the detached stroma is then excised to expose the Descemet’s membrane.

25. Hydrodelamination Technique-   A partial trephination and a lamellar keratectomy are carried out at a suitable depth. A small cut /depression is created in the deeper stroma. A 27-gauge needle attached to a syringe is inserted at the bottom of the depression, and saline is injected into the stromal bed, which whitens and swells. A fine spatula is then inserted through a small incision in the delaminated tissue and moved fan like in different direction to loosen the residual stroma which is then dissected to reach the Descemet’s membrane . A 5-mm DM area in front of the pupil is exposed .

26. Microkeratome Technique –   The advantage of this technique over other lamellar techniques is the relative ease of surgery and the low incidence of interface scarring and irregular astigmatism. The automated microkeratome is used to cut the donor lenticule , as well as the corneal disc in the recipient eye. The thickness of the cut can be adjusted in relation to the depth of the lesion, by choosing the proper plate size (up to 450 μm ). This technique has advantage of a smooth central host bed and a consistent and controlled bed diameter

27. Big Bubble Technique Combined with Zigzag Femtosecond Laser Incisions-- The use of a femtosecond laser for the dissection of anterior lamella in anterior keratoplasty was first described by Suwan et al in and latter by Price et al Farid in 2009. The technique combines the advantages of secure zigzag femtosecond laser wound construction with the aim to reduce the amount of postoperative astigmatism combined with the high-quality interface obtained with the big bubble technique

28. Clinical Outcomes over various techniques The techniques of dissection as well as surgeon's experience are main factors in determining the rate of true Descemet’s membrane (DM)exposure Sarnicola et al* found the highest rate (60%) with Anwar's big-bubble technique. Supplemented with viscoelastic dissection at the same session in the case of unsuccessful air injection, this rate increased to as high as 77% Viscodissection technique was the second most successful technique in baring the DM, with a rate of 58%, followed by the hydrodelamination (7%)

29. Complications Intraoperative Microperforation – Sudden softening eye and excursion of fluid or air into the interface. Occurrence 39% expert hand Manage – Air in AC- Continue dissection peripheral to perforation. Leaving Air bubble with supine position of patient Macroperforation – Convert PKP Pupillary Block Glaucoma - due to air bubble left in AC Avoided by Pupil dilation if air left Periodically examination eye in hour immediately after surgery

30. Graft host malapposition /edge irregularity Due to improper sizing of tissues Interface debris Fibers , bleeding

31. COMPLICATION POSTOPERATIVE Double AC Cause- Micro perforation, Entrapped Visco at interface Manage- Accelerated intracameral Air/ SF6 and drain interface flui d Persistent epithelial defects Suture related,ocular surface diseases,wound /edge problems Infections Suture related, lid adnexal abnormalities,poor hygiene,steroid use,reactivation of herpectic infections

32. Graft vascularization In cases of trachomatous keratopathy,chemical burns and SJ syndrome Epithelial , Subepithelial or stromal rejection Epithelium – Line of oedema Subepithelial - Subepithelial infiltrate Stromal – Oedema

33. Advantages of ALK less chances of postoperative inflammation as well as secondary glaucoma. No risk of endothelial graft rejection . No need for long term steroid prophylaxis Rapid functional recovery of vision. Very good best corrected visual acuity ( BCVA ) very low astigmatism. No significant endothelial cell loss . Penetrating Keratoplasty can be done if recurrences occur or Descemet's membrane perforation occurs intraoperatively. The criteria for quality of donor tissue are not very stringent

34. Endothelial keratoplasty DLEK DSEK DMEK

35. Endothelial Keratoplasty (EK) Purpose To remove the diseased recipient endothelium and replace with healthy donor corneal endothelium. In 1998,Dr.Gerritt Melles et al first described this technique involved large limbal incision and deep manual lamellar corneal dissection . Dr. Mark Terry modified by small incision 5mm rename the Procedure “ Deep Lamellar Endothelial Keratoplasty (DLEK) ” Next Evolution by Melles was the substitution of the patient dissection with Descement’s stripping and “ Descement’s stripping Endo Keratoplasty (DSEK) ” coined

36. Why there is need for EK ,an alternative to PKP?????

37. DLEK/DSEK/DMEK vs PKP EK procedure preserves the normal corneal topography to allow faster visual recovery  Astigmatism after DLEK surgery was 1.63 ±0.97D* , In contrast, after standard PKP surgery was between 4.00 and 6.00D After DLEK surgery and in DSEK 18-35% endothelial cell loss from preoperative donor counts.After 5 years its was 54%. After PKP, the cell count has been at 6months- 34% cell loss from preoperative donor counts and 69% at 5 years. Less immunological rejection rates than PK.PK>DSEK>DMEK Tectonically stable globe No suture related complication

38. Patients Selection Endothelial Diseases Fuch’s endothelial dystrophy Pseudophakic bullous keratopathy Aphakic bullous keratopathy Iridocorneal endothelial syndrome

39. SURGICAL PROCEDURE LARGE INCISION TECHNIQUE(DLEK) A scleral access incision is placed at superior limbal region of size 9.0 mm SCLERO CORNEAL LAMELLAR POCKET IS MADE USING A CRESCENT BLADE STRAIGHT DEVERS DISSECTOR IS THEN USED TO EXTEND THE POCKET TO MID PUPILLARY REGION OF THE CORNEA THEN A CURVED DEVERS DISSECTOR EXTENDS THE POCKET COMPLETELY TO THE LIMBUS FOR 360 DEGREES, CREATING A TOTAL AREA OF DEEP LAMELLAR POCKET

40. THE RESECTION OF THE POSTERIOR RECIPIENT TISSUE IS DONE WITH AN INTRASTROMAL TREPHINE (TERRY TREPHINE) ONCE THE BLADE IS IN POSITION IN THE POCKET, IT IS ROTATED ALONG THE ARC OF 9.0 MM SCLERAL INCISION   RESECTION OF THE RECIPIENTS DISK IS COMPLETED USING CINDY SCISSORS ONCE THE POSTERIOR RECEIPIENT DISK HAS BEEN CUT 360 DEGREES, THE TISSUE IS REMOVED FROM THE EYE

41. DONOR TISSUE PREPARATION THE DONOR CORNEOSCLERAL FLAP IS PLACED ON AN ARTIFICIAL ANTERIOR CHAMBER WHICH IS COATED WITH HELON ON THE ENDOTHELIAL SIDE ARTIFICIAL ANTERIOR CHAMBER HEALON ON THE ENDOTHELIUM   THE DONOR TISSUE IS THEN CAPPED ONTO PLACE AND TREPHINATION IS CARRIED OUT TO ABOUT 60% DEPTH LAMELLAR DISSECTION IS COMPLETED USING CRESCENT KNIFE THE DONOR POSTERIOR DISC IS THEN PLACED ON A OUSLEY SPATULA THE DONOR DISC IS THEN SLOWLY INSERTED USING OUSLEY SPATULA THE SPATULA IS THEN GENTLY REMOVED FROM THE EYE LEAVING THE DONOR TISSUE BEHIND SUPPORTED BY AIR BUBBLE IN ANTERIOR CHAMBER 10-0 NYLON IS THEN USED TO CLOSE THE SCLERAL WOUND AND PREVENT THE ESCAPE OF DONOR TISSUE A REVERSE SINSKEY HOOK IS THEN USED FOR ENDOTHELIAL SIDE POSITIONING APPEARANCE AT THE END OF SURGERY

42. Descemet’s Membrane Stripping Automated Endothelial Keratoplasty (DSAEK) DSAEK It is a method of posterior lamellar keratoplasty in which the recipient bed is prepared by stripping off the recipient’s Descemet's membrane. Technique was popularized by Gerrit Melles in 1999

43. Indications of DSAEK Fuchs endothelial dystrophy (most common) Pseudophakic / Aphakic bullous keratopathy Post PK endothelial graft rejection Iridocorneal endothelial syndromes (ICE) After glaucoma filtration surgeries Eyes with anterior chamber IOL

44. SURGICAL TECHNIQUE RECIPIENT’S CORNEA WOUND CONSTRUCTION THROUGH A 3-5 MM SCLERO CORNEAL TUNNEL WITH HEALON FILLING THE ANTERIOR CHAMBER DESCEMETORHEXIS AND REMOVAL OF DESCEMET’S MEMBRANE AS A SINGLE DISK IS CARRIED OUT USING DEXATOME DESCEMETORHEXIS IS BEGUN IN THE DISTAL POINT FROM THE ANTERIOR CHAMBER ENTRY SITE AND CONTINUED IN CLOCKWISE FASHION. THE PERIPHERAL STROMA IS MADE ROUGH USING THE DSAEK SCRUBBER TO ENHANCE DONOR DISK ATTACHMENT TO RECIPIENT CORNEA

45. Graft insertion and positioning Forceps – charlie 2, goosey , kelman Sheets glide – sheets intraocular lens Busin glide-reusable funnel glide Insertors/injectors- endosertor,endoglide,neusidl After graft is inserted—air BUBBLE—10-12 MINS Anterior chamber and wound is closed by 3 interrupted nylon sutures Donor disk is uniformly adherent to the patient’s cornea

46. DONOR PREPARATION MOUNTED ON AN ARTIFICIAL ANTERIOR CHAMBER MANUALLY OR SEMI AUTOMATED MICROKERATOME FEMTOSECOND LASERS

47. DSAEK

48. DSEK/DSAEK - disadvantages Steep learning curve Higher endothelial cell loss rate in initial post op period Graft dislocation Pupillary block Reports of graft dislocation in vitreous cavity in aphakics Interface haze limiting 20/20 vision More hyperopic shift compared to DMEK

49. DMEK(Descemet’s membrane endothelial keratoplasty ) Transplantation of isolated donor endothelium and Descemet’s membrane. Steps – Isolation of donor DM and endothelium , recipient descematorhexis followed by donor insertion and positioning Donor preparation :DM isolated by direct peeling(SCUBA) or by injection of air to create a Big Bubble Donor tissue over 40 years of age is preferred Insertion – glass pipette or IOL catridge and injector, through 2.8mm corneal incision—unwrapping--air fill

50. DMEK --advantages Reduction of interface haze Less incidence of graft dislocation Shorter visual recovery as total corneal thickness remains same Larger donor surface provides more viable endothelial cells Less strong host graft apposition at interface allows easier removal of failed/rejected donor lenticule No costly instruments for donor lenticule preparation

51. disadvantages Difficult and more traumatic manipulation of rolled DM Higher endothelial cell loss rates with current techniques

52. DMEK Not suitable for Aphakics Large iris defects Previous pars plana vitrectomy

53. Surgical Outcomes Visual acuity-6/9 to 6/18 with DSEK DMEK has faster and better visual recovery DMEK – 6/9 or better vision Refractive results- mean hyperopic shift of 0.75 to 1.5D due to changes in posterior corneal curvature and increase in thickness in DSEK DMEK– 0.25 to 0.50 D hyperopic shift Endothelial cell loss- at 6months- 18-35 % , 54% at 5years Graft survival-55-100% in various studies

54. Complications of EK Early post operative raised IOP Pupillary block Appositional angle closure Graft Detachment/Dislocation-The most common complication following DSAEK surgery is dislocation of the graft due to difficulty in achieving air fill for required time or to maintain a firm eye. DMEK> DSEk Management-scraping, venting incisions, air, supine position, rebubbling Epithelial down growth- donor epithelial entrapment

55. Interface abnormalities- thickness irregularities due to manual dissection—folds and wrinkles in EK, incomplete removal of visco Haze due to proteoglycan deposition Infections Graft rejection- Lower in EK compared to PK, rejection PK>DSEK>DMEK Late endothelial graft Failure Steroid induced glaucoma

56. The future of keratoplasty Femtosecond Laser DSAEK • This laser is used to create flaps in LASIK and can be used to perform keratoplasty with different shapes of stromal cut. • The laser uses an infrared wavelength (1053nm) to deliver closely spaced, 3 microns spots that can be focused to a preset depth to photodisrupt the tissue within the corneal stroma. • Femtosecond laser is used to create a dissection plane on the donor cornea mounted on artificial anterior chamber. • Offers a potential advantage over microkeratome with regards to better sizing of the posterior lenticule . •Obtains a smooth surface and precise stromal cuts

57. SUTURELESS CORNEAL ADHESION Bioadhesive (Fibrin glue) Kaufman et al successfully used fibrin glue in small series of lamellar keratoplasty Photochemical keratodesmos is method of producing sutureless adhesion by applying a photosensitizer to wound surfaces followed by low energy laser irradiation. Laser promotes cross linkage between collegen molecules to produce tight seal without thermal damage.

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