Ординатура / Офтальмология / Английские материалы / Master's Guide to Manual Small Incision Cataract Surgery (MSICS)_Garg_2009

After pupil stretching, the pupil may be permanently larger than before, with crenated edges, particularly if it was very small and nondilatable preoperation. In these cases, it might be advisable to use a 6.0 mm or larger optic (I prefer 7.0 mm optics in all cases). This larger pupil is actually a benefit in allowing easier fundus viewing. I think you will be impressed by the ease and safety of this pupil stretching maneuver, and by the relatively normal appearance of the pupil postoperation.

ANTERIOR CAPSULOTOMY

Any type of capsulotomy works well with this procedure. I prefer a capsulorhexis. The capsulorhexis, however, needs to be made as large as possible to allow nucleus tip-up. A can-opener capsulotomy works well also and is used if there is difficulty with the capsulorhexis. For mature cataracts, capsular staining under an air-bubble with either ICG or Trypan Blue (Vision Blue®, from Dutch Ophthalmic) makes the capsulorhexis much easier (Figures 4.14A to D).

I prefer a Gimbel Utrata forceps for the capsulorhexis. This forceps has sharp tips so the capsule can be penetrated and the rhexis completed without changing instruments. I start in the middle and spiral out. Redeepen with viscoelastic anytime the tear wants to “head south” (Figures 4.15 and 4.16).

HYDRODISSECTION

Complete hydrodissection is done, with the cannula just beneath the anterior capsule, to loosen the nucleus and get it rotating freely. Generally one fluid wave to the right and one to the left will be adequate. I like to use a

spatula through the sideport and the hydrodissection cannula through the incision to bimanually rotate the nucleus after hydrodissection (Figure 4.17).

NUCLEUS DELIVERY

After capsulotomy, the 3.2 mm incision is enlarged to 7.0 mm. I find that a 5.2 mm keratome works best for this. The crescent blade also works fairly well. Attempt to maintain the internal self-sealing incision all the way across (Figure 4.18).

The chamber is refilled with viscoelastic. A Kuglen hook in the left hand nudges the nucleus gently away from the incision. The spatula catches the superior pole of the nucleus at the equator and tips it up. Using the two instruments, the nucleus is then cartwheeled through the capsulorhexis and pupil (Figures 4.19 to 4.22) into the anterior chamber (as an alternative, it may be “somersaulted” end-over-end into the anterior chamber).

If nucleus tip-up is difficult, aspirate the cortex off the top of the nucleus with the 0.3 IA tip, refill with viscoelastic, and attempt tip-up again.

Additional viscoelastic is placed beneath the nucleus. The lens loop is placed beneath the nucleus and the spatula on top. The nucleus is extracted, “sandwiched” between the two instruments. The outer portion of the nucleus will be sheared off with this technique, but it is soft and easily aspirated or irrigates out of the self-sealing incision with gentle pressure on the posterior wound lip (Figures 4.23 to 4.26).

If the nucleus breaks in two during removal, rotate the residual fragment so it is oriented with its long axis perpendicular to the incision. Add additional viscoelastic to blow the iris back and resandwich it (Figures 4.27 to 4.29).

Large brunescent nuclei may be extracted through a 7.0 mm incision by purposely breaking off a superior wedge, then rotating 90° and removing. This is done by placing the lens loop and spatula one-third of the way down the nucleus and pinching off a fragment, reducing its diameter. Then, rotate long axis perpendicular to the incision and sandwich (Figures 4.30 to 4.33).

CORTEX ASPIRATION

Cortex is aspirated with the technique of your choice. I prefer automated technique with 0.3 IA tip. Manual technique also works well. If there are damaged zonules or a break in the capsule, I go to a “dry” technique, with manual cortex aspiration with a 27 gauge cannula on a

3 cc syringe under viscoelastic. A noncohesive viscoelastic, such as Viscoat, works better in this situation than Healon. A Morcher capsular support ring is helpful in cases with damaged or absent zonules.

A safety suture is not necessary. If there is a tendency to iris prolapse, this usually means a selfsealing incision has not been obtained and an “X” suture will be required at the end of the case. Residual epinucleus can be washed out of the wound by slightly depressing the posterior lip while irrigating with the IA tip. This is somewhat more efficient than aspirating epinucleus. Stubborn cortex can be assisted into the 0.3 IA tip with the “potato masher” maneuver (Figure 4.34).

Subincisional cortex can be more easily removed by splitting irrigation and aspiration and inserting the

aspiration cannula through the side-port (Figure 4.35). These instruments and adaptor are available fairly inexpensively from ASICO (Table 4.1).

Viscoelastic is used to expand the capsular bag. A 7.0 mm lens fits snugly through the incision. If squeezing is required, hold the eye with the closed 0.12 forceps inserted into the side-port (holding the flap risks tearing it). Insert the leading loop of the lens first, then the optic to avoid loop crimping (Figures 4.36 to 4.38).

Aspirate viscoelastic. The internal flap is sealed by pressurizing the eye with BSS through the side-port. Blood in the wound gives a Seidel effect to demonstrate any leak. The chamber depth can also be observed to demonstrate no leak. If the chamber deepens with pressurization and does not shallow once the pressurization

cannula is removed, self-sealing is indicated. This should occur in 95 percent + of cases (Figure 4.39).

Conjunctiva is brushed over the wound and sealed with wet-field cautery (Figure 4.40).

CAVEATS

This technique is viscoelastic dependent. Be sure to have plenty of viscoelastic both in front of the nucleus and behind it when sandwiching. Attempting to remove the nucleus under air will result in striate keratopathy. This procedure does, however, work well with methylcellulose, or with any other viscoelastic.

When starting out, use a larger incision, possibly 8.0 mm; then gradually decrease the incision size as