Penetrating keratoplasty

popularly known as corneal transpalnt

1. PENETRATING KERATOPLASTY DR NIKITA JAISWAL

2. glossary INTRODUCTION TYPES INDICATIONS DONOR CORNEA & PRE OPERATIVE EVALUATION COMPLICATIONS

3. history 1905 by Eduard Zirm

4. introduction Penetrating keratoplasty (PKP). This comprises of replacing full thickness host corneal tissue with a full thickness donor corneal tissue.

5. TYPES OBTAINING A CLEAR VISUAL AXIS FOR VISUAL REHABILITATION TO ELIMINATE CORNEAL INFECTION TO PROVIDE SUPPORT IMPROVE APPEARNANCE OF EYES WITH A WHITISH CORNEAL SCAR

6. INDICATIONS OPTICAL Pseudophakic / aphakia Stromal corneal dystrophies Primary corneal endotheliopathies Corneal ectasias & thinning. Congenital corneal opacity Acquired corneal scars Non infectious ulcerative keratitis.

7. THERAPEUTIC NON HEALING INFECTIOUS KERATITIS INFECTIOUS KERATITIS WITH PERFORATION POST CHEMICAL INJURY

8. TECTONIC RECONSTRUCTION OF OCULAR SURFACE TO STRENGTHEN THE CORNEA IN CASE OF CORNEAL MELTS CORNEAL THINNING.

9. PREOPERATIVE EVALUATION

10. Ocular evaluation Ocular history Visual acuity Detailed examination: Underlying pathology IOP Vascularization Tear film status Presence of cataract Need for IOL exchange B-scan

11. Surgical technique PREOPERATIVE EVALUATION SURGICAL PROCEDURE SUTURING TECHNIQUE

12. PREOPERATIVE PREPARATION ANTI INFECTIVE AGENTS: PRE OP ANTIBIOTICS TREATMENT OF BLEPHARITIS 5% POVIDINE IODINE SOLUTION IOP CONTROL : PRE-OP MANNITOL HONAN’S BALLOON COMPRESSION AT 30 MM HG GOOD LID EXTRA OCULAR AKINESIA. ANESTHESIA : PERIBULBAR ANESTHETIA WITH OR WITHOUT LID BLOCK GENERAL ANAESTHESIA FOR PAEDIATRIC CASES APPREHENSIVE PATIENTS MENTAL IMPAIRMENT PUPIL DILATATION : PUPIL CONSTRICTION WITH 2% PILOCARPINE PUPIL DILATATION WITH MYDRIATICS WHEN CATARACT SURGERY IS PLANNED

13. Surgical procedure TREPHINIZATION GRAFT SIZING HIGHLIGHTS OF TRIPLE PROCEDURE

14. TREPHINATION DONOR TREPHINATION HOST TREPHINATION

15. Donor trephination Trephination of the donor button should preferably be performed from the epithelial side using an artificial anterior chamber with a large central opening Punching the donor from the endothelial side results in an undercut at the level of Descemet’s membrane with convergent cut angles

16. HOST TREPHINATION Horizontal positioning of limbal plane is indispensable Flieringa ring is only necessary in aphakic eyes The higher the intraocular pressure (iatrogenic!) the more divergent are the cut angles to be expected

17. Combination of donor trephined from the endothelial side (convergent cut angle) and mechanically trephined recipient (divergent cut angle) results in a triangular-shaped tissue deficit at the level of Descemet’s membrane which has to be compensated by suture tension resulting in central flattening

18. graft size has to be judged by the microsurgeon individually in every single case before recipient trephination to achieve the best compromise between immunologic purposes and optical quality ς donor trephination from the endothelial side results in a smaller donor button than trephine size and convergent cut angles (“undercut”) ς recipient trephination results in larger openings than trephine size and divergent cut angles ς this discrepancy makes a donor “oversize” of ≥ 0.25 mm necessary ς same size grafts are feasible if the donor is created by means of an artificial anterior chamber from the epithelial side ς undersizing the graft for simultaneous correction of myopia in keratoconus is not recommended (watertight wound! irregular astigmatism!)

19. Hessburg -Barron suction trephine. A Recipient trephine with cross-hairs for centration; B Donor trephination is performed from the endothelial side

20. Graft A good optical performance requires a larger graft, whereas a low rate of immunologic graft reactions tends to be seen with smaller grafts .

21. Triple procedure Comprises of grafting+extraction of cataract+IOL implantation. PEARL: Cataract should be removed regardless of the stage as later it will progress & then it can cause damage to the corneal endothelium. Vitreous can be removed with vannazs or wide bore canula .(host –graft junction should be free of vitreous) IOL insertion-routine insertion if not then the lens can be sutured to the iris or to the sclera.

22. MEDIUM FOR CORNEAL PRESERVATION Short term storage Intermediate storage Long term storage

23. Short term storage Method: Moist chamber method: when globe is preserved at 4’c with saline humidification for upto 48 hrs . Endothelial viability depends on: Enucleation within 6 hours of death. Cool enviornment maintainence until enucleation Maintaining 4’C Careful slit lamp examination

24. INTERMEDIATE TERM STORAGE

25. M c CAREY –KAUFMAN MEDIUM ORIGINAL TC199 5% Dextran Bicarbonate buffer Penicillin&streptomycin (100unit/ml) later substituted by gentamycin in conc of 50-200µg/mi MODIFIED Added phenol red as a pH indicator Osmolarity -290mOsm/kg pH is 7.4 k/as modified MK medium Cornea can be stored at 4’C upto 4 days

26. LONG TERM STORAGE ORGAN CULTURE DONOR CORNEA UPTO 35 DAYS NO REMARKABLE LOSS OF ENDOTHELIAL CELLS . CRYOPRESERVATION ONLY TRUE PRESERVATION CAPELLA & KAUFMAN Corneoscleral rim—in a series of soln of dimethyl sulfoxide (DMSO) upto 7.5%.---placed for 10mins— upto -80’C & subsequently stored at -160’C indefinitely.

27. Suturing techniques Suture material Suture technique (interrupted, single running, double running, combinations) Length of stitch Depth of stitch Angle of stitch towards graft-host apposition Suture tension “Depth disparity”

28. Correct position of second cardinal suture ( arrow ) is facilitated by orientation tooth (donor) and corresponding notch (host)

29. Surgical outcomes GROUP 1 EXCELLENT PROGNOSIS >90% KERATOCONUS CENTRAL/PARACENTRAL CORNEAL SCARS STROMAL DYSTROPHY GROUP 2 VERY GOOD PROGNOSIS EXPECTED SUCCESS RATE OF 80-90 % APHAKIC/P’PHAKIC CORNEAL ODEMA & BULLOUS KERATOPATHY INACTIVE HERPETIC KERATITIS MACULAR STROMAL DYSTROPHY

30. GROUP 3 FAIR PROGNOSIS-SUCCESS RATE 50 TO 80% Active microbial /herpetic keratitis Mild chemical injury Moderate keratoconjunctivitis sicca GROUP 4 POOR PROGNOSIS-<50% Severe chemical injury Radiation injury Steven’s johnson syndrome Multiple failed grafts

31. COMPLICATIONS INTRAOPERATIVE SCLERAL PERFORATION Trephination related Retained descement membrane Endothelial damage Intraocular hemmorhage Vitreous loss POSTOPERATIVE Wound leak Persistent epithelial defect Post op inflammation Suture related Raised IOP Ant synechiae formation LATE: Post PK astigmatism Graft rejection Post pk glaucoma

32. Graft rejection Time : rarely within 1 st month but it can be till 20 years post PK These rejections takes 4 clinical forms EPITHELIAL REJECTION:in this immune response—donor epithelium-lymphocytes causes elevated linear epithelial ridge— centipetally The rejection has been reported at the rate of 10% of patients experiencing rejection Usually seen in the post op period (1-13 months)

33. SUBEPITHELIAL REJECTION They may present as subepithelial infiltrates Alone they may cause no symptoms Lymphocytes direction is unknown Can be seen in broad,tangential light These leave no sequelae if treated But it may presage the more severe endothelial graft rejection STROMAL REJECTION: This is uncommon If present can present as neovascularization In very prolonged bouts the stroma can become necrotic

34. ENDOTHELIAL REJECTION THE MOST COMMON TYPE 8%-37% loss of significant NUMBER OF ENDOTHELIAL CELLS LEADS TO GRAFT REJECTION inflammatory cells seen in anterior chamber. endothelium lost— stroma thickens—epithelium odematous pts have--- photophobia,redness,irritation,halos around light.

35. Treatment Frequent steroid instillation Dexamethasone 0.1% Prednisolone0.1% Periocular injection of triamcinolone acetonide for severe rejection or non compliant patient. PREVENTION Early attention to loosening sutures Use of cyclosporine,tacrolimus,mycophenolate .

36. preservative-free topical steroids hourly for 24 hours are the mainstay of therapy. the frequency is reduced gradually over several weeks. steroid ointment can be used at bedtime as the regimen is tapered. high-risk patients can be maintained on the highest tolerated topical dose (e.g. prednisolone acetate 1% four times daily ) ○ topical cycloplegia (e.g. homatropine 2% or atropine 1% OD or BD daily). ○ topical ciclosporin 0.05% to 2% may be of benefit, but the onset of action is delayed. ○ systemic steroids oral prednisolone 1 mg/kg/day for 1–2 weeks with subsequent tapering; if given within 8 days of onset IV methylprednisolone 500 mg daily for up to 3 days may be particularly effective, suppressing rejection and reducing the risk of further episodes. ○ subconjunctival steroid injection (e.g. 0.5 ml of 4 mg/ml dexamethasone ).

37. KERATOPROSTHESIS Group 1 With good blink rate Wet eye BOSTON Type 1 K Pro Group 2 Significant conjunctival scarring Dry eye & exposure Alpha cor keratoprosthesis

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