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Devices help manage small pupils during cataract surgery
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There are several way to deal with small pupils during cataract surgery. Microincision cataract surgery can be safely performed, provided that the diameter of the pupil is sufficient to allow performing a capsulorrhexis of 4 mm to 5 mm.
Small pupil phaco
Precautions to be taken during the first stages of surgery are the creation of a long corneal tunnel and the use of an adhesive or high molecular weight viscoelastic.
The best phacoemulsification technique in these cases is the central “phaco chop” technique, which prevents contact and potential damage to the iris (Figure 1, click here to see the technique).
The use of “push and pull” hooks helps get the iris out of the way while visualizing residuals and aspirating the cortex (Figure 2, click here to see the technique).
IOL implantation and viscoelastic removal are easily carried out with standard maneuvers.
Figure 1. The best phacoemulsification technique in these cases is the central ‘phaco chop’ technique.
Figure 2. The use of ‘push and pull’ hooks helps get the iris out of the way while visualizing residuals and aspirating the cortex.
Images: Galan A
Figures 3a and 3b. The easier and most effective way of stretching the pupil is by using two hooks: one Osher hook and one ‘push and pull’ hook.
Figure 4. Iris retractors can be used with small but non-fibrotic pupils.
Figure 5. The wide aperture makes cortex aspiration and IOL implantation easy and safe.
Figure 7. Pupil dilation using a special pupil expander, the Beaver-Visitec I-Ring.
Figure 8. The ring is removed with the OVD still in the chamber, through the same injector used for insertion.
Small pupil — stretching
When pupils are small due to fibrosis of the pupil edge, mechanical stretching is the best way of expanding them to a sufficient aperture for MICS. The easier and most effective way of stretching the pupil is by using two hooks: one Osher hook and one “push and pull” hook (Figures 3a and 3b, click here to see the technique).
The following maneuvers are as previously described: creation of a long corneal tunnel and use of an adhesive OVD, central “phaco chop” to avoid contact with the iris, the use of a “push and pull” hook during aspiration of the cortex, IOL implantation and viscoelastic removal.
Small pupil — retractors
Iris retractors can be used with small but non-fibrotic pupils (Figure 4, click here to see the techique). In these cases, mechanical stretching does not work and may stimulate further pupil constriction. Iris retractors are placed in a diamond configuration through four small incisions. Each retractor is gently pulled to gradually obtain the aperture that allows the surgeon to gain access to the crystalline lens. A central “phaco chop” technique is used to avoid contact and damage to the iris. The wide aperture makes cortex aspiration and IOL implantation easy and safe (Figure 5, click here to see the technique). At the end of surgery, the iris retractors are removed and the pupil goes back to its natural round shape (Figure 6, click here to see the technique). However, the traction may lead to sphincter lesions in some cases.
Small pupil — dilator ring
The best and safest way of obtaining pupil dilation is by using a special pupil expander, the Beaver-Visitec I-Ring (Figure 7, click here to see the technique). Compared with other rings currently available on the market, this device is easier to insert and remove. Insertion is performed through a dedicated injector after filling the anterior chamber with viscoelastic. The I-Ring expands the pupil to a diameter of 6 mm, which remains stable during surgery. Phacoemulsification, aspiration and IOL implantation can be performed using whatever technique the surgeon feels comfortable with. The ring is removed with the OVD still in the chamber, through the same injector used for insertion (Figure 8, click here to see the technique).
Although the ring is extremely pliable and the traction is evenly distributed along the circumference of the pupil, immediately after removal of the ring, the pupil sphincter may temporarily show indentations.
- For more information:
- Alessandro Galan, MD, OSN Europe Edition Board Member, is head of ophthalmology at Sant’Antonio Hospital, Padua, Italy. He can be reached at Ospedale Civile Sant’Antonio, Via Facciolati 121, Padova, Italy; email: alessandro.galan@gmail.com.
Disclosure: Galan reports no relevant financial disclosures.