TABLE 6–1 STEPS IN THE MANAGEMENT OF THE

SMALL PUPIL

1.Make a clinic note regarding dilation status so that preoperatively you know what to expect from pharmacologic dilation

2.Add a nonsteroidal antiinflammatory drug (NSAID) and phenylephrine 10% viscous if a patient dilates poorly

3.A retrobulbar block assists pharmacologic dilation

4.Always have a Beehler pupil dilator sterile and ready to use anytime the pupillary size appears too small

5.Always have one set of micro-iris hooks available

6.Use additional postoperative steroid, NSAID, and meiotics

0.2to 0.4 cc of 1% unpreserved lidocaine is injected into the anterior chamber. It is then deepened with viscoelastic. Usually a 3.0-mm clear corneal incision

1.75to 2.00 mm into clear cornea is established. If indicated, a Kuglen hook is then used to examine the iris for adhesions and mobility. Peripupillary adhesions can often be broken at this time. Additionally, both the blunt viscoelastic cannula as well as gentle viscodissection can be used to sweep under the iris to release posterior synechiae (Fig. 6–1).

Occasionally, thin veneer-like membranes will remain on the anterior capsule. These should be removed with a Utrata (not sharp-tipped) or a Kelman McPherson forceps, as this will allow better control of the capsulorrhexis. If the pupil is large enough after these steps, no further manipulations are necessary. As all iris manipulation causes iris damage and

TABLE 6–2 PROBLEMS IN THE MANAGEMENT

OF THE SMALL PUPIL

1.Too much phenylephrine 10%, especially the aqueous form, may cause intractable cardiac arrhythmias

2.Do not operate in the presence of a small pupil; first make it larger

3.Disregard the increased iris fragility throughout the remainder of the case

4.Implantation of a 5.5-mm or smaller optic intraocular lens (IOL)

subsequent breakdown of the blood–aqueous barrier, the less the iris is manipulated, the better.

IRIS STRETCH—TWO INSTRUMENTS

Simple stretch techniques often work and usually eliminate the need of scissors or retractors. One simple method utilizes two instruments. After filling the anterior chamber (AC) with viscoelastic, and before creating the capsulorrhexis, two Kuglen hooks or Y hooks are employed. One is inserted through the incision and the other through the paracentesis. The instrument tips are moved toward the limbus employing a slow, constant bimanual stretch (Fig. 6–2A). A single stretch will often be adequate. However, to obtain maximum pupil size a second stretch 90 degrees away will usually create a significant increase in the pupil diameter1,5–7 (Fig. 6–2B). The chamber can then be re-deepened with viscoelastic, and surgery commenced.

Histologically, it is observed that stretching causes micro–sphincter tears. Too rapid of a stretch may increase the length of these microtears, creating macrotears and permanent secondary mydriasis. Done slowly and gently, the end result is usually a round, functional pupil.

IRIS STRETCH—BEEHLER DILATOR

Moria Company (no. 18032), in association with Beehler, has come up with an instrument that produces a four-point stretch using one hand. It requires an incision of 3.0 mm or larger, and is reusable and extremely effective (Fig. 6–3). Due to its delicate nature and poor finish, it must be carefully cleaned of adherent viscoelastic after each use. It may then be sterilized and held available, prepackaged, for use at a moment’s notice. A three-point dilator, with a smaller diameter barrel and an angulation for small clear corneal incisions (2.5 mm), is also available. A similar but smaller two-point dilation instrument, the Keuch pupil dilator, is produced by Katena (K-3-4950).

To use this family of instruments, the AC is filled maximally with viscoelastic prior to capsulorrhexis. It may be helpful to partially release the lid speculum to aid in maximally deepening the AC. The instrument is inserted through the incision turned sideways such that the hook on the barrel is pointed laterally. The superior aspect of the barrel is used to engage the anterior wound while depressing the posterior wound. Gentle fine oscillation aids the entry of the barrel into the AC. Once inside the AC, the hook is rotated downward and the subincisional iris is engaged. The splines are then extended and manipulated to push the pupil margin opposite to the incision. The pushing of the splines against the iris is slowly performed. Gentle movement of the entire instrument toward the wound accompanies it.

The splines are then retracted, the instrument is pushed forward to release subincisional iris, the hook is rotated laterally, and the entire instrument is removed. This clever instrument will usually provide a pupil that is 5 to 7 mm in diameter. Its mechanism of action is to cause innumerable microtears of the fibrotic pupillary sphincter. Therefore, the iris is often somewhat flaccid after its use. Additional precautions, such as low or zero vacuum, must be employed to prevent phaco damage to the iris, which seemingly wants to be aspirated into the phaco tip.

FIGURE 6–3 A Beehler pupil dilator is utilized to stretch the pupil. Each of the splines are engaged at the pupil margin opposite the wound. The hook on the barrel engages the iris near the wound. The splines are then gently wiggled to and fro to increase the micro–sphincter tears, resulting in more effective pupil dilation.

IRIS STRETCH—MICRO-IRIS

RETRACTORS

Both metal (titanium) and flexible (nylon) iris microretractors are available to dilate the pupil. The titanium retractors can be steam sterilized and are therefore reusable. Both nylon and titanium employ a silicone cinch for adjusting the iris position. Regardless of the type, four equidistant paracentesis incisions are required (Fig. 6–4A). The surgeon should be careful to place the paracenteses in the correct position. If they are too anterior (too far into clear cornea), the iris will be pulled anteriorally when the silicone cinches are tightened (Fig. 6–4B). The result will be an inability to pass the phaco tip over the iris. Even if the phaco tip can be placed into the AC, significant iris chafe will result.

In addition, if the paracentesis is too parallel to the iris, the retractors may cause the iris edge to “curl” up and cause difficulty (Fig. 6–4C). The iris retractors are capable of creating great amounts of pupil dilation if the silicone cinch is tightened maximally. It is not necessary to enlarge the pupil to the maximum, as signficant damage to the iris sphincter is likely to occur (Fig. 6–4D). This will result in severe postoperative pupil irregularity and dysfunction. The retrac-

A

B C D

tors should therefore only be withdrawn and cinched to the point where the surgeon believes that pupillary aperture is adequate for the performance of the capsulorrhexis and phacoemulsification. It is also important to slowly enlarge the pupil by tightening the silicone cinches sequentially, a little bit at a time to minimize iris tears. It is also prudent to slightly release the subincisional retractors to decrease the contact of the iris with the phacoemulsification needle, thereby diminishing iris chafe.

SILICONE PUPIL EXPANDER

John Graether has developed a clever silicone pupil expander, which is available in two diameters. To use it, first select the desired diameter ring. In an AC deeply filled with viscoelastic, a small sleeve retracts the iris subincisionally. An injected sleeve is then placed across the AC and seated on the iris. It is then released from the injector and seated on the pupillary margin. After the phacoemulsification and implantation of the lens, the silicone is removed.

MULTIPLE SPHINCTEROTOMIES

This technique, devised by Howard Fine, is most effective when combined with bimanual stretching. It is also effective combined with the use of the Beehler dilator, although the Beehler dilator is so effective it can usually be employed without actually cutting the sphincter. After filling the AC with viscoelastic, eight equally spaced mini-sphincterotomies are performed. Each incision into the pupillary sphincter is 0.5 mm in length (Fig. 6–5A). Thus, only part of the sphincter is incised. Cuts, which transect the sphincter fully, are to be avoided, as they will create a fixed and dilated postoperative pupil.3 Rapozzo scissors are the best instrument for this, but any small intraocular scissors such as Vannas or Gills can be used (Fig. 6–5B). Once all the cuts are in place, the pupil should be stretched, slowly and gently, as noted above (Fig. 6–5C).

SECTOR IRIDECTOMIES WITH OR

WITHOUT IRIS SUTURE

FIGURE 6–4 (A) Micro–iris retractors shown with the appropriate amount of pupillary retraction. (B) The paracentesis is too high in the cornea. The iris is folded toward the cornea, making it impossible to pass the phaco tip into the AC without damaging the iris. (C) The paracentesis is too low. The iris is bunched up as the retractor is retracted. Passage of the phaco tip without iris damage is unlikely.

(D) The correct placement of the paracentesis is demonstrated. Note the iris is retracted and there is adequate space for the passage of the phaco tip.

The techniques as noted above are almost always successful at providing an adequate pupil to allow phacoemulsification. Therefore, in the interest of comprehensive description, but relegated to a historical prospective, are sector iridectomies with or without a suture. A huge increase in pupillary area can be achieved by either superior or inferior iridectomies. First effecting a peripheral iridectomy and then extending it through the pupillary mar-

A

C

gin, one may perform a subincisional sector iridectomy.8

Inferiorly a preplaced 10-0 Prolene suture can also be used.9

CAPSULORRHEXIS

If the pupil stretching has resulted in a large pupil, the capsulorrhexis may be of standard size (i.e., 5.0 to 5.5 mm).

If the pupil stretch has resulted in only a moderate or small pupil, the surgeon may be tempted to venture phaco through a smaller than normal pupil and rhexis. Alternatively, some have recommended tearing the rhexis under the pupil where the tearing edge cannot be visualized. Both these options are risky and therefore unacceptable. A surgeon faced with these options must recognize the fundamental problem. That is, the pupil diameter has not been sufficiently enlarged. Thus, an additional method of

B

FIGURE 6–5 (A) The Rapozzo scissors are used to make 1⁄2-mm cuts in the iris sphincter. (B) Eight sphincterotomies have been created. Note appearance of the iris prior to stretching. (C) The combination of sphincterotomies and stretching allows the creation of a large pupillary aperture.

dilation must be employed. Once pupil size is adequate, capsulorrhexis can be accomplished.

PUPIL STRETCH AFTER INITIATING

CAPSULORRHEXIS

Stretching the pupil by any technique, after beginning the capsulorrhexis, is to be avoided. It is all too easy to catch the capsule edge with the stretching instrument, leading to a capsular tear. In addition, the shallowing of the anterior chamber during stretching maneuvers may lead to posterior positive pressure tearing the capsule outward with resultant likelihood of complications.

HYDROSTEPS

It has been previously noted that the mechanically dilated pupil is more flaccid than one that has been pharmacologically dilated. Therefore, if hydrosteps