Fig. 13.1
Clear corneal wound construction for anterior vitrectomy
Create two radial vitrector wounds on either side of the phaco wound, by approximately 1–2 clock hours from the phaco wound (see Fig. 13.1). The two wounds are to be used separately for the vitrector and can therefore be constructed using an appropriate size of microvitreoretinal (MVR) blade (or similar) for the vitrector being used. The original side port(s) can be used as the vitrector wounds, or enlarged as necessary to fit the vitrector.
With the infusion on, place the self-retaining AC maintainer into its wound using a rotatory screwing movement and check for any visible leakage from the original phaco wound. Resuture if there is any leak. Secure the AC infusion with tape to maintain its orientation and prevent inadvertent removal or kinking.
Inject a diluted suspension of triamcinolone into the AC via a vitrector wound using a Rycroft AC cannula (or similar) attached to a 5 ml Luer Lock syringe. The triamcinolone acetonide injectable suspension 40 mg/ml version should first be diluted with balanced salt solution (BSS) to a concentration of approximately 1:3. Surgeons should note that there are different preserved and nonpreserved versions of triamcinolone acetonide injectable suspension available depending upon the geographical location. When injecting the diluted suspension, the aim is to disperse its white particles throughout the AC, so that it acts as a particulate stain of any vitreous. This occurs as the white crystals of triamcinolone become trapped within the vitreous’ collagen bundles. It therefore highlights the otherwise colorless vitreous strands within the colorless fluid of the AC. Excess triamcinolone is removed during the vitrectomy. Therefore, utilizing intraocular triamcinolone in this way enables the surgeon to visualize and remove the vitreous from the AC more easily, as it not only acts as a marker for the vitreous but can also establish an end point for the anterior vitrectomy when no further attachment to vitreous is seen [4].
Slowly enter the AC with the vitrector via a vitrector wound. Use maximum cut rate throughout the anterior vitrectomy phase. Maximum cut rate is used to minimize traction on the vitreous and therefore the retina by minimizing pulsatile flow and volume per cut. Do not use the aspiration-only setting with the vitrector (i.e., cutter off) until the vitreous is cleared from the AC or the risk of retinal damage is further increased by the traction applied to the aspirated (rather than cut) vitreous strands.
Angle the vitrector cutter down and just through the PCR. Trim all visible vitreous, with care not to cut any other structures in the eye. Keep the vitrector wound in view at all times.
Swap vitrector wounds with the vitrector by carefully removing the vitrector from the vitrector wound being used and swapping to the other side if required for reasons of access. When exiting the eye, ideally stop aspirating, turn the infusion off momentarily, and swap to the other vitrector wound before turning the infusion back on. This limits inadvertent vitreous outflow through the wounds.
Repeat administration of the diluted triamcinolone suspension via a vitrector wound as much as necessary to ensure confidence in clearing all of the vitreous in the AC.
Anterior Vitrectomy Summary
- 1.
Inject dispersive OVD into AC.
- 2.
Give low-volume LA block (if topical LA).
- 3.
Suture phaco wound closed.
- 4.
Construct self-retaining AC maintainer wound.
- 5.
Construct vitrector port wounds.
- 6.
Insert self-retaining AC maintainer with infusion on.
- 7.
Inject diluted triamcinolone into AC.
- 8.
Cut vitreous from AC with vitrector.
Operating Room/Theater Staff PCR Preparation Summary
- 1.
Prime a dispersive OVD to hand to the surgeon.
If surgeon advises anterior vitrectomy:
- 2.
Open LA drug and equipment for on-table sub-Tenon’s LA block (or other type of block) by surgeon if patient is only under topical LA.
- 3.
Open 10–0 nylon sutures (or similar) and instruments for wound closure.
- 4.
Prepare anterior vitrector and self-maintaining AC maintainer equipment.
- 5.
Change phaco machine settings/set up vitrectomy machine for anterior vitrectomy.
- 6.
Prepare triamcinolone suspension 40 mg/ml diluted to 1:3 with balanced salt solution (BSS) in a 5 ml Luer Lock syringe and primed Rycroft cannula (or similar).
- 7.
Prepare intracameral acetylcholine chloride in a Luer Lock syringe and primed Rycroft cannula (or similar).
- 8.
If not routinely used, prepare intracameral cefuroxime 1 mg in 0.1 ml in a 1 ml Luer Lock syringe and primed Rycroft cannula (or similar).
13.4.3 PCR Case Scenarios
- 1.
Suspected PCR, but not confirmed. For example, pupil snap sign during hydrodissection (see others above). Proceed with caution, use a dispersive OVD as described above, and re-assess. If PCR is not thought to be present, carefully continue with reduced phaco machine fluidics (see 13.3).
- 2.
One small strand of vitreous in a wound with the IOL in place and otherwise uneventful surgery. We do not generally recommend the routine use of cellulose sponge-assisted anterior vitrectomy as it exerts vitreous traction by its very action. It is also less able to clear significant amounts of vitreous in the AC. However, cellulose sponges can be used in this particular scenario to manage a single strand of vitreous in a wound at the end of the procedure. The sponge is used to apply tension on the vitreous strand at the wound; then, scissors are used to cut the strand flush with the wound. The strand should then retract away from the wound and into the eye. This quick technique avoids making the wounds, the equipment, and extra time required for anterior vitrectomy. Surgeons should not enter the AC or touch the iris with the sponge or scissors, as the resultant drop in AC pressure can encourage more vitreous to enter the AC [3].
- 3.
Small, round PCR after removal of cortex/soft lens matter (SLM) but no vitreous movement into the AC. Utilize the dispersive OVD as above to partition the vitreous from the AC; however, as there is no vitreous in the AC, no anterior vitrectomy is required. Proceeding to careful direct IOL placement is therefore possible. We would advise ciliary sulcus IOL fixation in this situation. Therefore, a three-piece IOL with at least a 13 mm haptic diameter should be used. Occasionally, a small irregular PCR can be converted into a stable posterior capsulorhexis allowing capsular bag IOL fixation, but only by experienced surgeons and in rare circumstances. Dispersive OVD should be used liberally to maintain AC depth and vitreous partitioning during the procedure. Be aware that if the IOL later proved to be unstable, IOL removal from a capsular bag with a PCR can be difficult, with a significant risk of vitreous traction. Therefore, if there is any doubt, an IOL should not be implanted into the capsular bag.
- 4.
PCR with SLM present, but no vitreous movement into the AC. If a small PCR has occurred and a small amount of SLM remains, inject dispersive OVD as above and consider performing “dry aspiration.” For this technique, we would recommend setting up as for anterior vitrectomy (see above), but without the self-retaining AC maintainer and its infusion. While partitioning the vitreous and maintaining space in the AC using the dispersive OVD, use the vitrector on its aspiration-only setting (cutter off) to carefully remove the SLM. Optimally, a stripping motion of engaging SLM into the port is used. Rather than aspirating the SLM in the eye, the SLM is instead stripped from the eye by removing the vitrector and the engaged SLM though the vitrector wound. This avoids AC shallowing and reducing the risk of vitreous movement into the AC. Top-up the dispersive OVD into the AC via the other vitrector wound as much as necessary. If there is any doubt about vitreous movement, check with triamcinolone as above and proceed to anterior vitrectomy if required.
- 5.
PCR with SLM present and vitreous movement into the AC. Inject dispersive OVD and follow the anterior vitrectomy procedure as above to clear the vitreous from the AC. Once the vitreous is removed from the AC, carefully attempt to remove the SLM using the aspiration setting. Move the vitrectomy probe into the SLM area, engage with aspiration only, move the probe to the central pupillary area, and then engage the cut-aspiration mode to aspirate the SLM. This sequence avoids the risk of inadvertently cutting precious capsule or iris in the periphery while engaging the SLM. However, be vigilant for any vitreous, and remember to utilize triamcinolone if there is any doubt. If further vitreous movement does occur, revert to the anterior vitrectomy procedure immediately (see above), that is, stop using the aspiration mode on the vitrector and start using the cutter mode to clear the vitreous, or there is an increased risk of traction on the retina and its subsequent complications as described above.
- 6.
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PCR with vitreous movement into the AC, in the presence of nuclear lens fragments in the AC.
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Small nuclear lens fragment in the AC. This is a complex scenario. Inject dispersive OVD and perform anterior vitrectomy (as above). Once the AC is clear of vitreous, attempt aspiration of the nucleus or epinuclear material using aspiration (with high vacuum, but ideally capped or limited flow) or aspiration with a lowered cut rate if the lens material is soft. If it is harder, a bimanual crushing technique using a second instrument can be attempted. If impossible, return to the use of the phaco probe, but the phaco machine fluidics should be significantly reduced so that an almost dry aspiration technique is used to attempt to phaco/chop the nuclear fragments before removing the SLM. A variety of techniques have been described for this scenario using IOLs or lens glides to mechanically partition the nuclear material from the vitreous cavity and reduce the risk of vitreous aspiration. Unfortunately, all of the techniques are difficult and are therefore only to be attempted by experienced surgeons when no other options exist. Surgeons should be aware that with or without the use of an IOL or other barrier to partition the vitreous, such techniques still risk further egress of vitreous into the AC and the need to return to the anterior vitrectomy procedure. If this occurs, returning to the use of the vitrector is essential as the phaco probe is unable to cut the vitreous; it instead aspirates the vitreous, causing further traction on the retina. If the surgeon is not confident to attempt the above techniques or is plagued by recurrent movement of vitreous into the AC, proceed with the management described below for larger nuclear fragments in the AC.
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- (a)