8/20/2014
DESCRIPTION
Plasma Knife versus Conventional Scissors for In-situ Excision of Donor Corneoscleral button for the purpose of Penetrating Keratoplasty. Ashutosh Agarwal 1 , Radhika Tandon 1 , Namrata Sharma 1 , Jeewan S. Titiyal 1 , Rasik B. Vajpayee 1,2 - PowerPoint PPT PresentationTRANSCRIPT
04/22/23 1
Plasma Knife versus Conventional Scissors for In-situ Excision of Donor Corneoscleral buttonfor the purpose of Penetrating Keratoplasty
Ashutosh Agarwal1, Radhika Tandon1, Namrata Sharma1, Jeewan S. Titiyal1, Rasik B. Vajpayee1,2
1Department of Ophthalmology, All India Institute Medical Sciences, New Delhi, India; 2Centre for Eye Research, University of Melbourne, Melbourne, Australia
The authors have no financial interest in the subject matter of this poster.
04/22/23 2
Introduction
In IndiaPrevalence of corneal blindness is approximately 6.8 million of which about 1 million are bilaterally blind and 40,000 fresh cases are added every year.
Nearly 3.5 million good quality cornea donors are required, quite challenging with an annual meagre collection of 20,000 eyes. Rajesh Sinha, Namrata Sharma et al .Corneal Blindness—Present Status I CATARACT & REFRACTIVE SURGERY TODAY ,OCTOBER 2005: 59-64
Major obstacles include ineffective procurement of donated corneas as also failure to successfully convince the potential donors.
Tandon et al.. Factors Affecting Eye Donation From Postmortem Cases in tertiary Care Hospital (Cornea 2004;23:597–601)
In situ excision of donor cornea (compared to conventional Whole Globe Enucleation) ) is a
1. newer technique (last one decade)
2. swift and precise extraction with least damage to endothelium
3. prolific in enhancing the quality and utilization of donor corneas by reducing death preservation time
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Author/Group Study Design Infection Tissue Quality Comments
Rootman et al , Cornea 2007
468 corneas-300 by in-situ & 168
enucleated over 4 yrs
Lower incidence
mod. to severe haze &
folds in DM
No difference in
mean ECD
No difference in
tissue trauma level
mean ECD
Placed in storage medium earlier -- improve the overall initial quality.
Everts RJ et al –
Retrospective study
Cultures of post- PK CorneoScleral rim
PPV and sensitivity for
predicting subsequent
endopthalmitis were both zero
Post-op endopthalmitis
optimum specimens collected
treatment based on known eye pathogens
Vishal Jhanji et al, Cornea 2008
Prospective RCT
100eyes—50 in-situ & 50 enucleated
Risk of contamination is
equally low in skilled hands
Initial cell loss and corneal thickness
higher
3 mths Post op comparable
ECD
GC
Median VA
More Acceptable
Review of Literature: In-situ versus Enucleation
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Review of Literature (contd…)
Plasma Knife
Cutting
1. Safe, quick, atraumatic
2. By tissue ablation
3. Resistance free (minimum tissue traction)
4. No tactile sensation of making incision
5. Tip does not adhere to tissue
6. Lower frequency and power compared to laser
7. Application in a wide range of ocular surgeries
Plasma Knife can produce sharp cuts in the cornea while
minimal tissue damage seen beyond edges of the incisionPeponis et al ,Fugo Blade in Corneal Surgery ;Cornea 2006;25;206-208
Aims and Objectives
Systematic comparative prospective evaluation of two techniques of harvesting donor cornea by in-situ method with respect to:
Donor tissue microbiological contamination
Corneal endothelium in the donor and also the recipient following transplantation
Graft infection
Graft outcome in the recipient at three months
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Methodology
Donor selection YES
• Age <60 years• DPT < 6 hours
NO• Aphakia / Pseudophakia• Putting on ventilator for long time (>72hrs)• Hypotension
Recipient Selection Non-vascularized corneal opacity
Written consent from legal next of kin
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Methodology
Eyes were systematically randomized (Right/Left) for both type (Plasma Knife or Corneoscleral Scissors) and sequence of
extraction.
The eye cleaned externally with povidone iodine 10% for 3 mins
Irrigation of conjunctival sac with saline
Povidone 10% instilled in conjunctival sac and washed off with saline
The eye cleaned and draped
1st limbal swab for culture
Gatifloxacin 0.3% eye drops instilled
Cont………
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Methodology
After doing 360° peritomy, a scleral incision made (in conventional method) with surgical blade 3mm from limbus taking care not to enter the choroid
Corneoscleral rim excised using curved corneal scissors/ or Plasma Knife
Careful separation of cornea from underlying tissue care not to damage
endothelium
Second swab taken(S2)
Eyes put in McKarey Kauffman (MK) medium (transferred to eye bank)
A transparent plastic cap put over the eye
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Methodology
Comparative evaluation done for 2 techniques of in-situ excision i.e. Plasma Knife assisted versus conventional scissors
Preoperative EvaluationDonor tissue microbiological contamination (before and after excision)Evaluation and grading of donor cornea on Slit Lamp
Post operative follow up of graft recipientsPost-op. corneal endothelial statusGraft status at 3 months in terms of Central Corneal Thickness, Graft Clarity and Spectacle Corrected Visual Acuity Any associated complications like graft infection/ graft failure etc.
RESULTS: Donor Evaluation
Comparative Evaluation Plasma Knife ScissorsStatistical Coefficient
No. of Donors15(13+2 single eyed
donors)13
p= 0.597
(FET)
Median Age (years) 50 50 p=0.889
(MWT)
Endothelial Cell Density (cells /mm2) 2181.27±286.30 2103.15±186.75p=0.409
(MWT)
Death Preservation Time (hrs) 4.70± 1.39 4.75 ±1.48p=0.924
(MWT)
Baseline Microbial Contamination (before extraction)
11/15 10/13 p= 0.843
(CST)
Microbial Contamination after extraction
9/15 7/13p= 1.00
(FET)
FET=Fischer Exact Test, MWT=Mann Witney Test, CST=Chi Square Test
RESULTS: Recipient Evaluation
Comparative Evaluation
Plasma Knife
Day 7 Day 90
Scissors
Day 7 Day 90Statistical Coefficient
Endothelial Cell Density
1821±226 1633±245 1800±193 1639±175p7=0.982p90=0.612
(MWT)
Central Corneal Thickness
583.5±26.3 560.7±30.1 577.0± 21.9 586.62± 54.2
p7=0.519
p90=0.240
(MWT)
Median Graft Clarity 3+ 4+ 4+ 4+
p7=0.082
p90=0.686
(FET)
Mean Spectacle Corrected Visual Acuity
0.101±0.07 0.305±0.12 0.091±0.09 0.315±0.23p7=0.500p90=0.667
(MWT)
Graft Complications Nil NilGraft Infection
(Pseudomonas)Nil
p=0.464(FET)
FET=Fischer Exact Test, MWT=Mann Witney Test, CST=Chi Square Test
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Conclusion
Plasma knife is a safe and effective equipment for in-situ extraction of donor corneoscleral rim.