anterior vitrectomy
TRANSCRIPT
الرحمن الله الرحمن بسم الله بسمالرحيمالرحيم
Anterior VitrectomyAnterior Vitrectomy
· Mohamed Zaki (M.Sc) · Tanta University
Aim· Prevent intra/post-operative vitreous
traction
· Leave a clean anterior segment
· IOL implantation
Event
· * PCT
· * Zonular dialysis
1- Once you suspect
Keep irrigation till inject methyl
Vitreous flow from high to low pressure
2- Keep the AC formed
The anterior vitrectomy should be done through tight paracentesis (not the main wound)
Make new paracentesis to fit bare vitrector shaft using original side-port
for irrigation
3- Don’t sweep vitreous from the wound
Traction on the anterior vitreous is dangerous because of the strong, permanent vitreoretinal adherence at the vitreous base
· The vitreous cutter should be used to amputate any posterior connection to wound entrapped vitreous.
· OVD can be used to reposit vitreous through the incision
4- Adjust machine parameters
· High cutting rate
· Lowest effective flow and vacuum
· Irrigation → cut → aspiration
Irrigation Cutting Vacuum
Anterior vitrectomy
Low bottle hight
(to maintain normotension)
High600 - 2500 /
min
Low (150 – 250 mm Hg)
Lensectomy Low 300 / min
5- Technique
1. The irrigation is placed in the AC directed towards the AC angle
2. The vitrector is placed through the capsular tear directed to the optic nerve with the aspiration port facing up .
3. The cutter should be maintained in a central position and not moved peripherally to avoid stress on the vitreous base.
4. The vitreous is removed to a level just posterior to the capsule
5 -the cutter is moved forward into the capsular bag. The remaining lens matter is removed with the cutter, reducing the cut rate to 300 cuts/min and increasing vacuum.
6- The cortex is then engaged, using the
vacuum-only setting of the cutter, and stripped off the capsule..
· The cutter should be held stationary while suction is applied to reduce traction;
· The cutter tip should always be in view when activated.
video
End point : no vitreous in the AC & no vitreous in the bag
· * rounded pupil· * Clean incision· * Sweep infusion canula from angle to
angle· *Instill air or triamcinolone and rinse
away.
TAAC
· Diluted 1 : 10
· Should be completely removed by end of case ( IOP )
Types of anterior vitrectomy
Bi manual
Coaxial
Dry ( small amount of vitreous)
Parsplana anterior vitrectomy
(single pars plana port )
Coaxial
· Easy but may increase the tear· Irrigation is directed to the vitreous
lead to more prolapse.
Pars plana Anterior vitrectomy
· More efficent particularly in extensive prolapse
· Used also in traumatic lens sublaxation or angle closure glaucoma.
· Cutter should be visualized , surgeon should be familial with the technique
Residual cortex
· After completeing anterior vitrectomy
· Dry technique
· Or : with the vitrectomy cutter set to :· I / A / cut
Conclusion
• Maintain a closed chamber• Separate the infusion from the cutter • Use a low bottle height • Use a high cut rate • Use low to moderate aspiration • Identify any vitreous remaining with
triamcinolone stain • Preserve the capsule