How to perform an anterior vitrectomy

When the capsule breaks during cataract surgery, minimizing vitreous loss is key.

Issue: August 15, 2006

ByUday Devgan, MD

The capsule has broken, and now the planned routine cataract surgery has unexpectedly become complicated: Vitreous has prolapsed, there is still cataract material in the eye, and the patient is becoming restless. What techniques and settings can help us minimize vitreous loss, implant a posterior chamber IOL and ensure a satisfactory visual outcome for our patient?

Anesthesia

Uday Devgan

If you are doing your routine cataract surgery under topical anesthesia with a minimal amount of systemic sedation, now is the time to supplement your anesthesia. Adding topical anesthesia on the field as well as further intravenous sedation and narcotics is helpful to prolong patient comfort and prevent eyelid squeezing.

When the patient squeezes or elicits the Bell’s reflex, the posterior pressure increases and the vitreous is more likely to prolapse further. Avoid injecting further anesthetic in the retrobulbar space as this can also increase the posterior pressure. Intracameral lidocaine without preservatives is a better choice.

Machine settings and modes

The key for an anterior vitrectomy is taking your time and doing a thorough cleanup of any prolapsed vitreous. Lower the bottle height, lower the flow rate and lower the vacuum level to achieve a slow-motion effect. Set the vitreous cutting rate at the highest allowed on your machine, as this will exert the least traction on the vitreous.

Most phaco machines allow a choice of anterior vitrectomy modes, performing the cutting action either before or after aspiration. With an anterior chamber full of vitreous, it is important to set the mode so that vitreous cutting is performed before aspirating (Figure 1). When the goal is removal of residual cortex or small cataract pieces, a mode where aspiration occurs before cutting is helpful (Figure 2).

With an anterior chamber full of vitreous, it is important to set the mode so that vitreous cutting is performed before aspirating.

When the goal is removal of residual cortex or small cataract pieces, a mode where aspiration occurs before cutting is helpful.

Images: Devgan U

Incisions and positioning of instruments

It is critical to avoid using your primary cataract incision for the anterior vitrectomy. Using the large clear corneal incision is a mistake because it is too large for the vitrector and the ensuing leakage from the incision will only draw more vitreous anteriorly. Close the primary incision and put a suture through it. Split the anterior vitrector into two components: the irrigator and the vitreous cutter. Using a 20- or 21-gauge cannula on the irrigating line and inserting it via the paracentesis will maintain the anterior chamber while creating a fluid current to push the vitreous back.

A second incision for the vitreous cutter can be created at the limbus into the anterior chamber or via the pars plana into the anterior vitreous. Placing the vitreous cutter via the pars plana is more physiologic, as it will draw the prolapsed vitreous posterior where it belongs (Figure 3). With the vitreous cutter via a second paracentesis incision, care must be taken to avoid drawing vitreous into the anterior chamber (Figure 4).

Placing the vitreous cutter via the pars plana is more physiologic, as it will draw the prolapsed vitreous posterior where it belongs.

With the vitreous cutter via a second paracentesis incision, care must be taken to avoid drawing vitreous into the anterior chamber.

Images: Devgan U

Staining the vitreous

Consider staining the prolapsed vitreous with dilute preservative-free triamcinolone, as this will improve visualization and provide somewhat of an anti-inflammatory effect postoperatively. Draw 1 cc of triamcinolone (10 mg/cc) into a syringe, then attach a micro-filter and push the plunger to discard the solvent and trap the triamcinolone particles in the filter.

Now, re-suspend the triamcinolone particles by drawing up 2 cc of sterile balanced salt solution through the micro-filter. These steps can be repeated for further washing. Then the filter can be removed and a 25- or 27-gauge cannula can be attached, and the resultant triamcinolone suspension (now 5 mg/cc and preservative-free) can be injected via the paracentesis to stain the vitreous.

Surgical technique

The goal is to remove any remaining cataract pieces, clearing the anterior segment of any prolapsed vitreous, and to securely implant the IOL. Using plenty of viscoelastic to support the nuclear pieces is helpful to prevent losing them into the vitreous. Should a nuclear piece fall posterior, do not chase after it. It is far better to refer the patient to a retinal colleague for a pars plana lensectomy than risk a retinal break or detachment.

Keep the infusion cannula in the anterior chamber, above the vitreous cutter at all times, as this will prevent hydrating the vitreous. Performing a vitrectomy is a slow process for cataract surgeons who are used to quick surgical procedures, and patience is key to thoroughly remove the prolapsed vitreous. Stay central in the posterior chamber and avoid contact with the remaining lens capsule. Due to pressure gradients, the vitreous will tend to gravitate toward sites of wound leakage at the main incision and the paracentesis. Sweeping these areas with a second instrument or cyclodialysis spatula is helpful to draw the vitreous strands posterior. Once the anterior vitrectomy is complete, more of the triamcinolone suspension can be injected to double-check for the presence of residual strands of vitreous.

While the main incision is still sutured shut, it is important to inject viscoelastic via the paracentesis to prepare for IOL implantation and to maintain the pressure within the anterior chamber. At this point, the main incision can be opened and the IOL can be implanted, ideally with the haptics in the sulcus and the optic captured by the capsulorrhexis.

For more information:

Uday Devgan, MD, FACS, is in private practice at Devgan Eye Surgery in Los Angeles, Beverly Hills, and Newport Beach, California. Dr. Devgan is Chief of Ophthalmology at Olive View UCLA Medical Center and an Associate Clinical Professor at the Jules Stein Eye Institute at the UCLA School of Medicine. Dr. Devgan can be reached at 11600 Wilshire Blvd., Suite 200, Los Angeles, CA 90025; 800-337-1969; fax: 310-388-3028; e-mail: devgan@gmail.com; Web site: www.DevganEye.com. Dr.Devgan is a consultant to Abbott Medical Optics and Bausch & Lomb, and is a stockholder in Alcon Laboratories and formerly in Advanced Medical Optics.