Anterior segment surgeon can perform complete management of dropped nucleus

Using the phaco probe through the pars plana can eliminate the need for second surgery and reduce reliance on vitreoretinal surgeons.

Phacoemulsification is becoming increasingly popular worldwide. It is a safe procedure, but complications are possible. Though complications such as shallow anterior chamber and hard eye have largely disappeared with the phasing out of conventional extracapsular cataract extraction (ECCE), newer complications such as the dropped nucleus have increased with the advent of phacoemulsification. This is potentially serious, as retained lens fragments can induce severe uveitis, secondary glaucoma and retinal detachment, all of which can lead to potentially serious visual loss.

Literature review

Forty-nine percent of phaco surgeons have experienced at least one case of dropped nucleus; the overall incidence is said to be 1.1%.

The literature describes various approaches to tackle this problem. Commonly, a 3-port pars plana vitrectomy with or without the use of perfluorocarbon liquids has been described. Management is exclusively performed by a vitreoretinal surgeon.

As far as the timing of vitrectomy is concerned, confusion reigns supreme. Some believe that there is no difference in the visual outcome whether the vitrectomy is done early or late. Others believe that the results are better if the vitrectomy is done after the eye quiets down. Still others have found that immediate vitrectomy done by the cataract surgeon leads to disastrous complications. As far as using the phaco probe posteriorly is concerned, the major complication is retinal detachment as noted by Borne (24%) and Wong (12%). But Stenkula says that there is no retinal detachment (RD) if a posterior segment surgeon does the procedure.

Our study has attempted to provide a complete solution to the dropped nucleus during phacoemulsification in one sitting. Toward this aim, we have used the phaco probe through the pars plana because it is available immediately, it becomes easy to remove even large pieces and a second surgery can be avoided. Overall it is economical and less stressful for both the patient and the doctor.

Procedure

Over a period of 2.5 years, we performed 3,405 cases of phacoemulsification with IOL implantation. Of these, we experienced a dropped nucleus in 27 cases during phaco training programs. Patient age ranged from 43 to 69 years; 15 were male and 12 were female. Thirteen procedures involved the right eye and 14 involved the left eye. The causes for dropped nucleus included zonular dialysis in three cases and posterior capsular tear in 24 cases, with small tears in eight cases and large tears in 16 cases.

At the first sign of capsular tear or zonular dialysis, all maneuvers are stopped and the phaco probe is gently withdrawn. The anterior chamber is formed with viscoelastic and the situation is assessed. The ophthalmic technician staff is instructed to prepare for pars plana approach.

A pars plana infusion cannula is inserted in the lower temporal quadrant and adequate vitrectomy is done through another pars plana sclerotomy incision in the upper temporal quadrant. All vitreous in the anterior chamber is removed via the limbal incision while anterior vitrectomy is done via the pars plana.

When using the phaco probe through the pars plana, suction and power are kept at 45% to 50%. The tip is kept visible in the pupillary area. Phacoemulsification is started only when the fragments are engaged into the tip. The power is not used continuously to avoid heating up. Phacoemulsification is done in the mid-vitreous cavity, away from both the retina and the iris. For larger fragments that have fallen to the bottom, the phaco probe is very carefully turned posteriorly.

The vitrector can be used for removing small fragments rather than chasing after them with the phaco probe. One should not hesitate to make multiple entries with the phaco probe and the vitrectomy cutter while attempting to remove the dropped fragments, as they will not be engaged in the phaco tip unless they are freed from all surrounding formed vitreous.

During both vitrectomy and phacoemulsification it is very important to save the anterior and posterior capsules from further damage. Therefore, all instrument tips should be kept away from the capsule.

After adequate vitrectomy and complete phacoemulsification, the remaining cortex is cleared up (this can be done earlier if it obscures the posterior view). For this the pars plana infusion line is closed and the irrigation and aspiration (I&A) probe is used through the corneoscleral tunnel. Additional vitrectomy is done if needed.

Capsular support is assessed and the appropriate IOL is placed in the appropriate position, followed by vitrectomy, then the eye is closed.

Results

Of the 27 cases of dropped nucleus, IOLs were placed in the capsular bag in three cases having small PC rents and in five cases where a broad peripheral rim of the posterior capsule was available. Twelve cases had large rents extending to the periphery and four cases had only a small rim of posterior and anterior capsules remaining. In these cases the IOL was placed in the sulcus. The IOL was also placed in the sulcus in three patients with zonular dialysis.

Postoperatively, 17 patients had best corrected visual acuity of 20/20 and 20/30, followed by nine cases who were between 20/40 and 20/50 and one case with 20/60 vision. Four cases had raised intraocular pressure, five had corneal edema and one case suffered from cystoid macular edema, which disappeared with conservative treatment.

Discussion

With phaco on the rise, the incidence of dropped nucleus has also increased, especially during the learning phase. Our aim should be complete management, which involves not only removing the dropped nucleus and prolapsed vitreous successfully, but also saving as much capsular support as possible for IOL insertion behind the iris.

A phaco probe is more advantageous in removing a dropped nucleus than a vitreous cutter or a fragmetome, because of the large opening and better suction and phaco power.

When using the pars plana phaco probe anteriorly, the fluid currents help engage the free-floating fragments. When using it more posteriorly for large pieces at the bottom, care should be exercised in removing them and avoiding traction on the vitreous.

To save whatever capsule remains, the boundary of the iris must always be respected. All maneuvers in the anterior chamber are always through the limbus/corneoscleral tunnel. All maneuvers behind the iris are always through the pars plana only. Also, the vitreous cutter, phaco probe and the I&A probe are all kept at a safe distance from the capsule.

If the phaco tip is kept in the pupillary area with the I&A on, then usually most of the small fragments that remain floating can be easily engaged into the tip and then emulsified. An anterior segment surgeon can very well accomplish this part. Once the preliminary reconstruction of the anterior segment is done with proper placement of the IOL, the patient can then be referred to the vitreoretinal surgeon for any nonretrievable, posteriorly situated lens fragments.

Summary

The phaco probe was used via the pars plana in 27 cases of dropped nucleus. In all cases the IOL could be inserted behind the iris with good visual outcome.

The boundary between anterior segment and posterior segment is fast becoming blurred regarding surgical management of problems. An anterior segment surgeon sooner or later does require to deliver a complete solution to the patient’s problem.

Toward this aim, an anterior segment surgeon should also be able to handle the posterior segment in such situations. Further, it is not always easy or possible to have a retinal surgeon ready in all such cases. We personally feel that an anterior segment surgeon should handle such cases, as he is more sensitive toward the aim of respecting capsular support. However, before attempting this procedure, the anterior segment surgeon should have enough experience handling the posterior segment.

This procedure is not for all; it is a new method that is complete in itself for managing the dropped nucleus. We strongly feel that it is time for the anterior segment surgeon to be able to manage his own complications without having to rely completely on the vitreoretinal surgeon.

In our hands, this procedure has yielded a very good visual recovery with no major postoperative complications like retinal detachment, and requires only a few additional instruments like the pars plana infusion cannula and the vitreous cutter.

For Your Information:

• Ashok P. Shroff, MD, can be reached at Schroff Eye Hospital, Near Railway Station, Navsari, Gujarat, India 396445; (91) 2637-50565 or (91) 2637-50695; fax: (91) 2637-57695; e-mail: apshroff@yahoo.com. Dr. Shroff has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.

References:

• Borne MJ, Tasman W, et al. Outcome of vitrectomy for retained lens fragments. Ophthalmology. 1996; 103:971-976.
• Gilliland GD, et al. Retained intravitreal lens fragments surgery. Ophthalmology. 1992;99:1263-1269.
• Marghero RR, et al. Vitrectomy for retained lens fragments after phacoemulsification. Ophthalmology. 1997;104:1426-1432.
• Pande M, Dabbas T. Incidence of lens matter dislocation during phacoemulsification. J Cataract Refract Surg. 1996;22:737-742.
• Stenkula S, Buhr E, et al. Tackling the dropped nucleus. Acta Ophthalmol Scand 1998;76:220-223.
• Terasaki H, Miyake Y, Miyake K. Visual outcome after management of a posteriorly dislocated lens nucleus during phacoemulsification. J Cataract Refract Surg. 1997;23:1399–1403.
• Wong D, Briggs MC, et al. Removal of lens fragments from the vitreous cavity. Eye. 1997;11:37-42.