4. PROCESSING
IT MUST BE PERFORMED IN
• A LAMINAR AIR FLOW HOOD WHICH MEETS ISO CLASS 5 STANDARDS
• IN AN ACCREDITED OPERATING ROOM
TISSUE MUST PROCESSED IN SUCH A WAY AS TO PREVENT CROSS
CONTAMINATION AND LABELLING
5.
6. EVALUATION
THE ULTIMATE RESPONSIBILITY IS DETERMINING THE SUITABILITY OF THE TISSUE
FOR THE TRANSPLANTATION .
IT INVOLVES
1. GROSS EXAMINATION
2. SLIT LAMP EXAMINATION
3. SPECULAR EXAMINATION
7. GROSS EXAMINATION
• WHOLE GLOBE
EYE WITH EXCESSIVE STROMAL HYDRATION SHOULD BE DISCARDED
UNLESS SPECULAR MICROSCOPY CAN BE DONE FOR ENDOTHELIAL CELL COUNT
• CORNEOSCLERAL BUTTON
COLOUR OF THE TISSUE STORAGE MEDIA IS TO BE NOTED
FOREIGN BODY CONTAMINATION
10. SPECULAR EXAMINATION
• KONAN'S EYE BANK SPECULAR MICROSCOPE - HIGH QUALITY IMAGES OF THE DONOR
CORNEA.
• RAPID AND ACCURATE CELL COUNT, AS WELL AS OTHER PARAMETERS SUCH AS
POLYMEGATHISM AND PLEOMORPHISM.
• BUILT IN PACHYMETER TO MEASURE CORNEAL THICKNESS.
• DONOR CORNEAS MUST BE WARMED TO ROOM TEMPERATURE FOR AT LEAST 1 TO 2
HOURS BEFORE EVALUATION TO ELIMINATE ARTIFACTS THAT APPEAR IN THE
ENDOTHELIUM AT LOW TEMPERATURE.
• EXAMINATION CAN BE DONE EVEN WITH THE CORNEAS BEING KEPT INSIDE STORAGE
MEDIA, THUS MINIMIZING CHANCES OF CONTAMINATION.
• WARMING THE PRESERVED CORNEAS WILL NOT AFFECT THE ENDOTHELIAL VIABILITY.
• DONOR ENDOTHELIAL CELL DENSITY SHOULD BE GREATER THAN AT LEAST 1500
CELL/MM² TO ENSURE SUFFICIENT DENSITY FOR CORNEAL DETURGESCENCE.
13. EYE BANK - PRESERVATION MEDIA
• SHORT TERM (48HRS) - MOIST CHAMBER
• INTERMEDIATE TERM (4 DAYS)
• -MCCAREY - KAUFMAN MEDIUM - 4 DAYS
• K-SOL MEDIUM - 7 DAYS
• DEXSOL MEDIUM - 10 DAYS
• OPTISOL MEDIUM - 14 DAYS
• LONG TERM STORAGE - ORGAN CULTURE - 35 DAYS
• CRYOPRESERVATION - 1 YEAR
14. SHORT TERM STORAGE METHODS
MOIST CHAMBER STORAGE:
• STORAGE OF THE WHOLE GLOBE FOR SHORT PERIOD OF TIME AT 4 DEGREE
• IT IS A CLOSED CONTAINER WITH COTTON GAUZE MOISTENED WITH STERILE
SALINE
• CONTAINER IS NEVER COMPLETELY FILLED WITH LIQUID
• ADVANTAGES: 1.SIMPLICITY 2. NEEDS LITTLE EXPERTISE & MANIPULATION 3.
INEXPENSIVE
• DISADVANTAGES: 1.STORAGE TIME LIMITED TO 48 HRS. 2. ENDOTHELIUM
REMAINS IN CONTACT WITH AQUEOUS.
15. INTERMEDIATE TERM STORAGE METHODS
• TISSUE MEDIA PRESERVATION:
ADVANTAGES:
1.PROVIDES A CHEMICALLY DEFINED & STABLE ENVIRONMENT
2.HELPS SUPPORT & ENHANCES METABOLIC ACTIVITIES
3.REDUCES THE STROMAL SWELLING
4.KEEPS THE TISSUE UNDER STERILE CONDITION TILL USE
5.PROVIDES TIME FOR EB TO SEROLOGICALLY SCREEN THE DONOR FOR
COMMUNICABLE DISEASES
17. DEXTRAN
• KEEPS PRESERVED CORNEA THIN.
• INITIALLY 5% OF 5,00,000 MOL WT. DEXTRAN IS USED.
• IN NEWER MEDIA 1% OF 40000MOL.WT IS USED.
CHONDROITIN SULPHATE.
• IT IS AKIN TO NATURALLY OCCURRING GAG IN CORNEA.
• IT IS AVAILABLE FROM WHALE(TYPE A),WINE (TYPE B),SHARK(TYPE C).
• HIGH MOL.WT CHONDROITIN SULPHATE MAINTAINS DETUREGENCE WHERE AS
LOW MOL.WT HELPS RETAIN VIABILITY OF ENDOTHELIUM
• ALSO ACTS AS AN ANTIOXIDANT
18. MC CAREY KAUFMAN MEDIUM
• COMPONENTS
• TIC 199
• 5% DEXTRAN
• BICARBONATE BUFFER
• PENICILLIN AND STREPTOMYCIN WHICH WAS LATER SUBSTITUTED BY
GENTAMYCIN IN CON OF 50-200 MICRO GRAMS PER ML
19. MODIFIED MK MEDIUM
• WALTMAN AND PLAMBERG
• SUBSTITUTED 0.025 M HEPES BUFFER FOR BICARBONATE BUFFER
• PHENOL RED AS A PH INDICATOR.
• OSMOLARITY 290 MILLI OSM/KG
• PH 7.4
• STORAGE PERIOD 4 DAYS AT 4 DEGREE C.
21. ORGAN CULTURE METHOD
• UP TO 35 DAYS
• CORNEOSCLERAL BUTTON IS PLACED IN PETRI DISHCONTAINING 15ML OF
MEDIUM.
COMPONENTS OF ORGAN CULTURE MEDIUM
• EAGLE'S MINIMUM ESSENTIAL MEDIUM
• EARLE'S SALTS WITHOUT L-GLUTAMINE
• L-GLUTAMINE DECOMPLEMENTED CALF SERUM
• 1.5% CHONDROITIN SULPHATE
22. CRYOPRESERVATION
• CAN BE PRESERVED FOR AN INDEFINITE PERIOD OF TIME
• DEVELOPED BY CAPELLA AND KAUFMAN
• CORNEOSCLERAL BUTTON IS PASSED THROUGH A SERIES OF SOLUTIONS
CONTAINING INCREASING CONCENTRATIONS OF DIMETHYL SULFOXIDE(DMSO)
UP TO 7.5%
• IT ACTS AS MEMBRANE STABILIZER FROZEN AT A CONTROLLED RATE UP TO -80
DEG C
• SUBSEQUENTLY STORED AT -180 DEG
23. ADVANTAGES
• EMERGENCY SITUATIONS LIKE CORNEAL TRAUMA AND PERFORATION
• FOR PERFORMING BACTERIOLOGICAL STUDIES ON DONOR TISSUE AND HLA
COMPATABILITY STUDIES
DISADVANTAGES
• NEEDS EXPENSIVE EQUIPMENT AND HIGHLY TRAINED PERSONS
