eye banking

Eye Banking

1. Eye Banking and Corneal P reservation Bebika Phuyal Resident 1 st year KMCTH

2. EYE BANK: Non-profit community organization which deals with collection, storage and distribution of cornea for the purpose of corneal grafting, research and supply of other eye tissues for other purposes Primary function of eye banks is to provide safe, viable ocular tissue for transplantation & for teaching & research. Townley Paton: Eye bank in New York in 1959 Eye banking Association of America (EBAA): a pioneer in modern Eye banking system.

3. Functions of eye bank Collect donor human eyes, process them and make them available to eye surgeons for corneal transplant surgery Educate public for willing donation of eyes to be removed after death Motivate people to consent for removal of eyes when a relative or friend has died Research different ways and means to prolong viability and usability of donor cornea with particular reference to environmental factors

4. Structure of Eye Bank M e d i c a l s e ct i o n : M e d i c a l D i r e ct o r (a qualified corneal surgeon), Trained technicians Administrative Section: Eye Donation Counsello r, Social Worker , Health Educator

5. 1. MEDICAL SECtion Consent & history review Physical assessment Tissue evaluation Tissue preservation/storage Tissue distribution by following the medical quality of highest standard Testing

6. 2. Functions of the Administrative Section: Public awareness programs Liaison with government, local voluntary and other health care agencies Fund raising

7. E quipment s Refrigerator with temperature recording device Biological safety cabinet O peratio n theatre === last ma Slit - lamp Specular microscope Serology laboratory Sterilization facilities Enucleation and corneal excision instruments Preservation media and appropriate transportation system

8. Eye donation Only the cornea is used for transplant Eyes should be donated within 6-8 hours of death Total removal time is about 15-20 minutes More than two corneal blind persons can get sight due to a single person's eye donation Nobody is charged for making eye donation The only cost to encounter is one local telephone call It is replaced by artificial eyes to prevent disfigurement Cornea is free of cost to the recipients Identity of both donor and recipient is kept secret D oes not delay the funeral

9. Any g ender can donate eyes All religions endorse the practice of eye donation Age lower limit 18 months to 2 years Willing donation of one’s own eye during life Eyes from medico legal post mortem cases Eyes from unclaimed bodies A good donor cornea is A h ealthy cornea If r emoval of cornea soon after death (within 6 h ou rs) Who can donate eyes?

10. Problems of Eye Banking May die at distant places May not carry donation card There may be no facility of enucleation at the place of death The place may not be connected by a quick mode of transport The near relatives may not consider it necessary to inform Eye Bank and can even refuse to allow enucleation for psychological reasons Medical issues/contraindications

11. Steps of eye donation Donor selection Tissue retrieval Corneal examination T ransportation and Storage of corneal tissue Distribution

12. 1. DONOR SELECTION 1. Age of donor: N o influence of age on transplant outcome 2. Medical history review: Eye banks must have consistent policies for the examination and documentation of donor's a vailable medical records, medical history, c ause of death, medications, laboratory reports especially serology

13. 3. Legal consent taken from next of kin, if: Consented donor meets medical and social history screening criteria Physical assessment reveals no contraindication to donation Then, acquisition of donor tissue can be carried out

14. Contraindications for eye donation I. Systemic c onditions : potentially health threatening for the recipient(s) or pose a risk to the success of the surgery and shall not be offered for surgical purposes Absolute contraindications: HIV s eropositivity Rabies Active viral hepatitis Creutzfeldt-Jakob disease Relative contraindications: Subacute sclerosing panencephalitis Progressive multifocal leukoencephalopathy Reye’s syndrome Death from unknown cause including unknown encephalitis Congenital r ubella Active septicemia including endocarditis Leukemias Active disseminated lymphomas

15. II. Ocular conditions: Intrinsic eye disease : R etinoblastoma, active inflammatory disease (conjunctivitis, iritis, uveitis, vitritis , retinitis), congenital abnormalities (keratoconus, keratoglobus), m alignant tumors of the anterior ocular segment, central opacities pterygium Prior refractive procedures : R adial keratotomy scars, lamellar inserts, laser photo - ablation Anterior segment surgical procedures : C ataract, glaucoma

16. 2. TISSUE RETRI E VAL Enucleation i.e. surgical removal of the whole eye By in-situ corneo -scleral excision (globe is retained in the orbit)

17. Enucleation

18. Corneo - scleral button excision

19. 3. Corneal examination Gross in-situ examination: Slit lamp examination: Whole globe examination Thawed to room temperature for endothelium to function and deturgescence of cornea Corneo -scleral button examination Glass vial placed in a special corneal viewing chamber

20. Corneal epithelium Epithelial microscytic oedema, defects and debris Epithelial oedema is indicative of poor endothelial f unction Corneal stroma Screened for opacities, infiltration, edema and Descemet's membrane folds

21. c. Specular microscopy: Cell density Cell size, shape, uniformity, pleomorphism, and polymegathism Presence of corneal guttata Evidence of any old intraocular inflammation and endotheli al insult

22. Parameters obtained by cell analysis Cell density (CD) Coefficient of variation of cell area (CV) Percentage of hexagonal cells (6A)

23. Cell density (CD) Inversion of cell area i.e. 10 , 00,000 divided by average cell area (1mm 2 = 10 , 00,000um 2 ) Eg . Average cell area = 346 um 2 then CD = 10 , 00,000/346 = 2890 cells /mm 2 Excellent : CD of >3000 cells/mm 2 Very good : CD of 2500-3000 cells/mm 2 G ood : CD of 2000-2500 cells/mm 2 Fair : CD of 1500-2000 cells/mm 2 Poor : CD of 1200-1500 cells/mm 2

24. Coefficient of variation of cell area (CV) CV : Standard deviation of cell area/mean cell area Normal range : 0.20 - 0.30 Higher the CV (wide variety in cell sizes) , higher polymegathism Lower the CV , more stable the cornea

25. Percentage of hexagonal cells (6A) Represents the shape factor of cells ( p leomorphism ) I rre gula r ce l l shap es i n t r a u m a tiz ed e nd o t h e lium - elongation/triangle/octagon / square 6A is calculated as number of hexagonal cells/number of cells entered Higher the 6A , more stable the cornea >50% hexagonality is desirable

26. Normal Endothelial cells

27. Polymorphism and Polymegathis m

28. 4. Preservation of donor cornea Short-ter m preservation Intermediate-term preservation Long - term preservation

29. Eye Bank - Preservation Media Short t erm (48 hrs ) : Moist c hamber Intermediate t erm : McCarey - Kaufman medium - 4 days K- Sol medium - 7-10 days Dexol medium - 10 days Corneal storage medium/ Optisol - 2 weeks 3. Long term storage: Organ Culture - 35 days Cryopreservation - 1 year

30. 1. Short term storage methods a. Moist chamber storage: Storage of whole globe for short period of time at 4 o C Usable eyeballs transferred to autoclaved wide-mouth bottles containing sterile cotton gauze pad  adequate antibiotic solution and sterile saline is instilled to moisten the pad  eyeball rests on the pad in a mouldable clamp with cornea straight up and without touching any part of bottle Tight screw cap in bottle to prevent fluid entering in it even if ice has melted in the container Thermocol container - provision for carrying one or two pairs of eyeballs with ice adequate for 18-24 hours transport

31. Advantages S implicity N eeds little expertise and manipulation I nexpensive Disadvantages S torage time limited to 48 h ou rs E ndothelium remains in contact with aqueous

32. 2. Intermediate term storage methods a. Modified McCarey -K aufman medium (1974) Components Tissue culture medium-199 5% dextran HEPES buffer Gentamicin- 50-200 mg/ml Phenol red as pH indicator Osmolality 290 mOsm /kg, pH 7.4 Stored in 20cc of medium at 4 o C Increases the endothelial viability of tissue and prolongs storage time to 96 hours

33. b. K-sol medium: Components 2.5% chondroitin sulphate in tissue culture medium-199 - prevents swelling of tissue HEPES buffer 100mg/ml gentamicin sulphate Osmolality- 310 mOsm /kg, pH 7.4 Storage period 7-10 days at 4 o C

34. c. Corneal storage medium/ Optisol Components Tissue culture medium-199 5% dextran 1.35 % chondroitin sulphate HEPES buffer 100mg/ml gentamicin sulphate Non-essential amino acids Storage period 2 weeks at 4 o C d. Dexol medium Composition similar, along with anti-oxidants Storage period - 10 days

35. INGREDIENTS Dextran C hondroitin sulphate Electrolytes pH buffer system Antibiotics Non-e ssential amino acids Anti - oxidants

36. D e x t ran Keeps preserved cornea thin 5 % of 40 , 000 Da mol w t is used Chondroitin sulphate A kin to naturally occuring GAG in cornea High mol. wt chondroitin sulphate maintains detu rgescence where as low mol. wt helps retain viability of endothelium Also acts as an antioxidant

37. Tissue culture media Provides a chemically defined and stable environment Helps to support and enhance metabolic activities Reduces the stromal swelling Keeps the tissue under sterile condition till use Provides time for Eye Bank to serologically screen the donor for communicable diseases

38. 3. Long-term preservation methods a. Organ-culture method Corneo -scleral button with endothelial side up is placed in Petri dish containing 15ml of medium C omponents Eagle’s minimum essential medium with HEPES buffer Earle’s salts without L-glutamine 1% L-glutamine 1.35% 50,000 Da mol wt chondroitin sulfate 2.5% fetal bovine serum 90 mg/ml gentamicin sulfate Tissue maintained in Petri dish for 2-3 days with one or two changes of medium at 34 o C in 5% CO2 Stored at 34 o C in 130ml of medium in sealed bottle, at least 35 days

39. b. Cryopreservation C an be preserved for an indefinite period of time Developed by CAPELLA and KAUFMAN Corneo - scleral button is passed through a series of solutions containing increasing concentra t ion of DIMETHYL SULFOXIDE(DMSO) up to 7.5%  a cts as membrane stabilizer F rozen at a controlled rate upto -80 o C S ubsequently stored at -180 o C

40. Advantages Emergency situations like corneal trauma and perforation For performing bacteriological studies on donor tissue and HLA compatibility studies Disadvantages Needs expensive equipment and highly trained persons

41. 5. Distribution of Cornea Distribution to only hospitals and ophthalmologists registered under HOTA ( Human Organs Transplantation Act) Maintenance of waiting list Distribution record Feedback from the hospital receiving cornea

42. CORNEAL TRANSPLANTATION: Keratoplasty / Corneal grafting Operation in which abnormal corneal host tissue is replaced by healthy donor cornea. Types: 1. Penetrating keratoplasty (full-thickness grafting) 2. Lamellar keratoplasty (partial-thickness grafting Anterior lamellar keratoplasty : Superficial & deep & Posterior lamellar keratoplasty

43. History: Late 19 th & earlier 20th century: Reisinger , Von Hippel & Elschnig Lamellar keratoplasty : less popular because of remarkable success of penetrating corneal graft technique.

44. Indications: 1. Optical i.e. to improve vision: corneal opacity, bullous keratopathy , corneal dystrophies, advanced keratoconus . 2. Therapeutic i.e., to replace inflamed cornea not responding to conventional therapy. 3. Tectonic graft i.e. to restore integrity of eyeball e.g. after corneal perforation & in marked corneal thinning 4. Cosmetic i.e. to improve appearance of eye.

45. TYPES: Corneal scarring or disease confined to anterior third of cornea: SALK Extensive stromal disease & healthy endothelium, keratoconus , post infectious keratitis & corneal dystrophy or scarring : DALK Primary endothelial dysfunction like Fuchs corneal dystrophy, pseudophakic bullous keratopathy (PBK) or a failed corneal graft: EK

46. PK : Combined epithelial, stromal & endothelial disease or with a failed graft with high astigmatism. Severe ocular surface disease or multiple graft failures: Keratoprosthes

47. ANAESTHESIA: Depending on age & patients cooperation: local or general anesthesia Peribulbar or retrobulbar injection Lidocaine 2%, bupivacaine 0.75% & hyaluronidase .

48. Examination: Visual potential. Neurologic or intraocular factors Media opacity, uncontrolled glaucoma, amblyopia , macular abnormalities, retinal disease or optic nerve damage Ocular surface abnormality: rosacea , dry eyes, blepharitis , trichiasis , exposure keratopathy , ectropion , entropion .

49. Intraocular pressure (IOP) Ocular inflammation Prior corneal diseases & vascularization : h/o herpetic keratitis Peripheral corneal melting: rheumatoid arthritis Treat prior to surgery.

50. Preparation of recipient eye: Globe: stabilized with bridle sutures passed beneath SR &IR. A trephine: gently to mark extent of graft needed. Hessburg -Barron suction trephine, Hanna trephine , Castroviejo trephine Hanna Trephine System : Less recipient edge undercutting & precision of cut depth. Disadvantages: cost, complexity & reduced visualization of cornea Femtosecond laser : Limited accessibility, increased costs

51. Partial-thickness trephination followed by controlled entry into AC using a No. 75 Beaver blade or a continued trephination i.e. stopped as soon as aqueous egress shows AC has been entered Suction is released & viscoelastic is injected. Recipient button is excised using forceps & corneal scissors The edge of recipient bed is made perpendicular for optimal graft–host apposition Smooth, uniplanar recipient bed

52. Preparation of donor eye: Trephination of tissue i.e. centering previously excised corneoscleral donor tissue, endothelial side up, in concave well of a cutting block apparatus that approximates cornea's shape. Use of calipers to measure the corneal diameters Slightly oversized 0.25–0.5 mm compared with recipient bed.

53. Trephination: hand-held trephine, universal punch & Katena trephine blade attached to a gravity corneal punch All cut donor from endothelium to epithelium. From epithelium to endothelium: Hanna artificial anterior chamber. Donor tissue is fashioned in a manner similar to that of recipient counterpart which reduces donor-recipient disparity & astigmatism

54. Interrupted sutures : Usuallly16- 24 in number 12 o’clock & 6 o clock so as to bisect the corneal button then 3 & 9 o’clock sutures Healing is rapid

55. The tension as an independent vector, generating central steepening & local flattening. Vascularized or thinned cornea: as subsequent selective removal may be necessary to prevent advancement of vessels or to control astigmatism

56. Continuous sutures: Speedy placement intraoperatively & better tension distribution & healing. Suture passes may be placed radially to donor - recipient wound Advantages: ease removal postoperatively. Disadvantages: sectoral loosening or cheese wiring which may compromise the entire closure

57. The combined interrupted & continuous suture technique: The interrupted sutures may be removed earlier after PK in order to reduce corneal astigmatism The continuous suture remains to protect against wound dehiscence.

58. Intraoperative Complications: Damage to lens &/or iris from trephine, scissors Irregular trephination & Inadequate vitrectomy Poor graft centration on host bed Excessive bleeding from iris & wound edge vascularized host corneas) Choroidal hemorrhage & effusion Iris incarceration in wound Damage of donor endothelium & Presence of remnants of retained descemet’s membrane in recepient

59. Post operative: 1.Wound leak 2. Flat chamber/ iris incarceration 3. Glaucoma 4. Endophthalmitis 5. Primary endothelial failure 6. Persistent epithelial defect 7. Microbial keratits 8. Recurrence of primary disease

60. Suture-related problems: Excessive tightness Loosening & breakage of running suture Infectious abscesses usually localized around loose, broken, or exposed sutures Noninfectious (toxic) suture infiltrates Giant papillary conjunctivitis from exposed knots Vascularization along suture tracks

61. Broken running suture Suture abscess Toxic infiltrates Giant papillary conjunctivitis

62. Late complications: Various corneal dystrophies and infections may recur in grafts Graft rejection: Epithelial rejection: epithelial line, which represents replacement of donor epithelium by that of the recipient. Subepithelial rejection – multiple subepithelial infiltrates limited to corneal graft may be observed

63. Endothelial rejection 21% Severe type: keratic precipitates, iritis & corneal edema: a Khodadoust line Pain, photophobia, redness & decreased vision

64. Topical corticosteroids. Epithelial: Corticosteroid drops increased to hourly Endothelial: hourly or more often) until process is reversed. Subconjunctival injection Systemic corticosteroids: oral or intravenous: in severe cases but are usually not necessary.

65. ASTIGMATISM: Readjust or remove sutures. Release of suture tension at I month postoperatively using cornea topography as a guide if single suture type is used. Relaxing incisions: if astigmatism even sutures been removed.

66. Artificial Cornea ( Keratoprosthesis ): Procedure designed to help patients whose conditions are the most difficult to treat, such as multiple graft failures or deep neovascularization of the cornea. Chronic bilateral inflammation from Stevens-Johnson syndrome or pemphigoid Synthetic keratoprosthesis Boston K-Pro AlphaCor

67. LK: advantages Minimal requirements for donor material Reduced incidence of allograft rejection Reduced risk of entry into AC: avoids risks of glaucoma, cataract, RD, CME, expulsive hemorrhage & endophthalmitis Shorter wound healing time

68. Anterior lamellar transplantation: Superficial stromal dystrophies & degenerations Superficial corneal scars Multiple recurrent pterygium Corneal thinning & melting Superficial corneal tumors Congenital lesions ( eg , dermoid ) Keratoconus Selective infections, including acanthamoeba

69. Partial-thickness trephination : performed on the host in the desired location and to the desired depth Dissection of diseased area on host tissue by blade Or microkeratome

70. Superficial lamellar keratoplasty technique Separation of cadaveric cornea : Martinez dissector or a cyclodialysis spatula, is used to separate gently the cornea along the lamellar cleavage plane through the entire cornea Donor tissue is harvested: -trephine is placed on the cadaveric globe in the size and the shape desired - circular lamellar graft is being harvested

71. The lamellar tissue is sutured to the host bed Depth of the suture is about 90% of the corneal stroma’s depth

72. DEEP ANTERIOR LAMELLAR KERATOPLASTY: To create smoothest recipient bed by removing all stromal tissue overlying recipient pupillary zone while leaving behind recipient DM & endothelium intact 3 techniques available : Depth of corneal dissection is visualized by filling AC with air(air- endothelium interface) By injecting viscoelastics to DM (Anwar’s big bubble) Femtosecond laser

73. Post operative complications : Inflammatory necrosis of graft Technically more difficult than PK & more time-demanding, May cause opacification & vascularization of interface, which may limit visual function

74. POST LAMELLAR KERATOPLASTY : 2 techniques: microkeratome -assisted & deep stromal pocket approach. Deep stromal pocket: created across cornea through a superior scleral incision. In microkeratome -assisted: posterior lamellar disc is sutured onto recipient posterior stromal rim using 10-0 or 11-0 nylon. The knots are rotated & buried & anterior stromal flap is sutured. With deep stromal pocket approach: donor posterior lamellar disc is placed within recipient rim via anterior chamber but not sutured

75. DESCEMET STRIPPING AUTOMATED ENDOTHELIAL KERATOPLASTY: Involves removal only of diseased endothelium along with Descemet membrane through a corneoscleral or corneal incision. Folded donor tissue is inserted through small incision.

76. Indication: Fuchs corneal dystrophy Pseudophakic bullous keratopathy (PBK) & Repeat corneal grafts due to endothelial cell failure Iridocorneal endothelial syndrome (ICE)

77. Descemet Stripping Automated Endothelial Keratoplasty ( DSAEK): Stripping Descemet's membrane: - Glide insertion of donor tissue - Air is tamponaded to appose the donor graft to the host stromal bed.

78. Advantages over PK: Better globe integrity & stability with scleral or clear corneal incision as compared to a full-thickness central corneal incision Corneal incision only sutured no graft Elimination of corneal suture- related problems Less induced postoperative corneal astigmatism Rapid visual rehabilitation with less concern for ocular surface disorders

79. Complications: Poor microkeratome dissection Incomplete removal of Descemet's tissue Poor centration of donor tissue during trephination Intraocular hyphema Posterior dislocation of donor tissue Epithalial ingrowth Primary graft failure Endothelial cell loss

80. REFERENCES Daniel M Albert, Joan W Miller, Dimitri T Azar . Albert & Jakobiec’s Principle and Practice of Ophthalmology, Volume 1, 3rd edition, 2008. Jack J Kanski . Clinical Ophthalmology, 9th edition, American Academy of Ophthalmology. External disease and Cornea, Section -12, 2019-20

81. THANK YOU