Anterior vitrectomy

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