47. 25 g vitrectomy for diabetic traction retinal
detachment
Steve T. Charles (Memphis)
Advantages of 25G Tools
25G Cutter
• Port-Based Flow Limiting Reduces Iatrogenic Retinal Breaks Due to Sudden Elastic Deformation of ERM
Thru Port
• Port Closer to Tip Facilitates ìVerticalî Access to ERM
• Smaller Diameter Facilitates ìLateralî Access to ERM
25G Laser
• Small Spot Size Facilitates Use for Non-Contact Coagulation of Vascular Attachment Points After
Delamination
Requirements for Use of Vitreous Cutter for ERM
Port-Based Flow Limiting Reduces Surge & Iatrogenic Retinal Breaks After Sudden Elastic Deformation of ERM Through Port
• High Cutting Rates Limit Flow
• 25G Limits Flow
Convoluted Detached Retina
Precise Low Vacuum Control w/ Fast Proportional Response to Decreasing Footpedal Vacuum Command
Port Closer to the Tip
Vit Cutter
Welded End vs. Spin Closed
Port Closer to Tip
Cutter Delamination
Inserting Cutter Between ERM & Retina Causes Iatrogenic Retinal Breaks
Foldback Delamination – Cutter Against ERM ìBehindî Margin of ERM, ERM Folds Back Into Port
Conformal Delamination - Side/Oblique Approach, Not Port Up, Rotate Cutter Around Longitudinal Axis to Control Angle of Attack, FollowRetinal Contour
Curved Scissors
Always Use Curved Scissors for Conformal Delamination and Access Segmentation
Never Use Vertical or Horizontal (135°) Scissors
Direction of Delamination
Inside-Out (Best)
• Central Retina Thicker
• Central Retina Redundant
• Central Retina Stronger
• ERM Thicker Centrally
• View Better Centrally
• Detach ERM Vessels From Optic Nerve Blood Supply
Outside-In
• Causes Breaks Just Outside Arcades (PRP, chronic RD, or ischemia induced atrophy)
• Breaks at Vitreous Base from Traction on PVC
• Occasionally Needed
Inside-Out Delamination
Before PVC Truncation for Diabetic TRD
Used if Minimal/No PVD (aggressive creating of a PVD causes retinal breaks)
ERM is Virtually Always Contiguous With Posterior Vitreous Cortex & Easily Visualized & Removed After Inside-Out Delamination of ERM
Prior Teaching Was That Truncation of Posterior Vitreous Cortex Should Always Precede ERM Dissection
Inside-Out Delamination Before PVC Truncation Technique Developed by Charles, Subsequently Called ìEn Blocî by Abrams et al and
initially described as outside-in with forceful traction on vitreous cortex
Advantages of Disposable
Forceps & Scissors
Small Diameter 25/23G Tools Are Easily Damaged During Cleaning & Sterilization
Optimal Gripping & Cutting Performance in Every Case
No Risk of Contamination (TSE/BSE, etc.)
Reduced Per Case Cost Because of Elimination of Cleanup, Sterilization, Packaging, Storage, Backup, and Inventory Costs
Current Role of Segmentation
Access Segmentation to Expose Delamination Plane
Dense ERM with Marked Adherence to Thin Atrophic Retina
• Peripheral Retina is Normally Thinner
• Heavy Prior PRP
• Marked Ischemia
• Chronic TRD Causes Atrophy
Post Vitrectomy Bleeding
Very Common
May Take Months to Clear
May Require Reoperation
Follow with Ultrasound If Other Eye OK
Full Vitrectomy (not ìwashoutî) With Scissors Delamination of Recurrent ERM, Bipolar or Laser to NVE, Pre-PPV Avastin
25G Rebleeds Less Than or Equal to 20G
No Evidence That Air, Viscoelastics, Thrombin, or Factor 13 Reduce Post-Op Hemorrhages
Ways to Reduce
Post-Vitrectomy Hemorrhage
Epiretinal Membrane Dissection Only as Needed for TRD Management and Macular Attachment
Better Hemostasis
• Intravitreal Avastin 5-7 days Before PPV
• Coagulate Vascularized ERM Attachment Points with Laser After Delamination
• PRP (pre-op, intra-op, post-op)
Pre, Intra, Post-Op Blood Pressure Control
Two Compartment Eyes Retain Blood: Phakic or IOL
Intravitreal Avastin Use w/ PPV
Intravitreal Avastin 3-7 Days Before PPV, If Any Active NV
Several Published Case Series Since July 2005 Indicate That Pre-PPV Intravitreal Avastin Reduces Intraoperative and Post-Operative
Bleeding (Avery, et al)
Injection Greater Than One Week Before PPV Can Result in Development of TRD or Progression of TRD Due to Rapid NV Regression and
Cicatrization
Garee Thomas Recommends Injecting Avastin at the End of Every Diabetic PPV
Stanley Chang Uses Avastin for Rebleeds (in my opinion one effect is to cause regression of VEGF driven NV at pars plana wounds, mistakenly
called fibrovascular ingrowth)