Extracapsular cataract surgery using capsulorhexis with viscoexpression via a limbal section

R.L. Burton, F.R.C.S., F.R.C.(Oph), Sharron Pickering

ABSTRACT Two hundred consecutive patients had extracapsular cataract surgery by capsulorhexis and viscoexpression. Capsulorhexis, attempted in 195 eyes, was successful in 87.7%. Viscoexpression was attempted in 162 cases and successfully delivered the nucleus in 87.7%. There were five cases of zonule rupture, one of posterior capsule rupture, and two of vitreous loss. If the capsulorhexis is larger than 5 mm, viscoexpression can be safely used on all cataracts, regardless of nuclear density, and is the ideal transition to phaco­emulsification.

Key Words: extracapsular cataract extraction, hydrodissection, hydroex­pression, viscoexpression

Pathological studies by Assia et al. 1 have proved that capsulorhexis ensures lens stability and centra­lion. Yet delivery of the nucleus through an intact capsulorhexis can be difficult in extracapsular cataract extraction (ECCE). Corydon and coauthors2

-6 devel­

oped the techniques of hydroexpression and viscoex­pression and have shown that viscoexpression is safer than hydroexpression because of the slower, more controlled delivery of the nucleus.

MATERIALS AND METHODS Two hundred patients had ECCE by a single sur­

geon (R.L.B.) between February and October 1992. The cases were unselected and consecutive. Fifty-four patients were operated on under general anesthesia and 146 under local anesthesia using a peribulbar tech­nique. Hydroexpression and viscoexpression were per­formed using the techniques described by Corydon and coauthors. 2

A superior rectus suture was placed and a superior limbal conjunctival perimetry performed. Mter dia­thermy of the wound, a partial-thickness, 8 mm to 9 mm section was performed 1 mm behind the limbus. A small entry was made into the anterior chamber, which was then filled with sodium hyaluronate (Rea­Ion®) viscoelastic. A continuous curvilinear capsula­rhexis (CCC) using forceps was made. A 30-gauge,

U-shaped cannula was fashioned from a disposable 30-gauge Rycroft cannula using an artery clip. The section was opened and the cannula placed under the edge of the anterior capsule at 12 o'clock. An initial wave of hydrodissection was created.

The cannula was then attached to the Healon sy­ringe and the Healon injected in the track in which hydrodissection was performed. The Healon accumu­lated behind the nucleus, dislocating the superior pole forward into the anterior chamber. The cannula was turned on its side and passed behind the nucleus to 6 o'clock. The lower pole of the nucleus was dislo­cated anteriorly into the anterior chamber with the cannula. The cannula was turned once again so the hook was facing anteriorly and the nucleus impaled upon it. The nucleus was then removed from the eye.

In some eyes with a soft nucleus, the nucleus could not be removed from the anterior chamber with the U-shaped cannula and so was removed with an irri­gating vectis. When viscoexpression was unsuccess­ful, the nucleus was removed with a Rycroft cannula to "tyre lever" it out of the capsulorhexis or by making two relieving incisions in the capsulorhexis. The nu­cleus was then delivered with an irrigating vectis. Three radial 10-0 nylon sutures were placed before irrigation and aspiration (1/A) and the lens placed in the capsular bag.

Presented at the 3rd American-International Congress on Cataract, IOL and Refractive Surgery, Seattle, May 1993.

Reprint requests to R.L. Burton, F.R.C.S., F.R.C.(Oph), Eye Department, West Norwich Hospital, Bowthorpe Road, Norwich, Norfolk NR2 3TU, United Kingdom.

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Fig. 1. (Burton) Best corrected preoperative visual acuity (LP = light perception; HM = hand motion; CF = counting fingers).

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At the end of the procedure, the Healon was re­moved and subconjunctival Cefuroxime® and Bet­nosol® were injected. Betamethasone drops were used three times a day for two weeks.

RESULTS Figure 1 shows preoperative best corrected visual

acuity. Capsulorhexis was attempted in 195 eyes. In the 5

eyes in which CCC was not attempted, 1 had a pupil stuck down with posterior synechia and 4 had white, mature cataracts. A beer-can capsulotomy was per­formed in these cases. The capsulorhexis success rate was 87.7%. In the 29 eyes in which capsulorhexis was not attempted or was unsuccessful, the nucleus was delivered with an irrigating vectis. Hydrodissection resulted in hydroexpression in 9 cases. In the remain­ing 162 cases, viscoexpression was attempted and was successful in 142 (87%). Viscoexpression was unsuc­cessful in 20 cases, and the nucleus was removed with a Rycroft cannula in 15 and by two cuts in the cap­sulorhexis in 5. Complications occurred in 7 cases (Table 1).

Figure 2 shows best corrected visual acuity at two months and Figure 3, astigmatism at two months.

DISCUSSION Capsulorhexis is now the method of choice in cat­

aract surgery. In addition to the advantages of lens centration described by Assia et al., 1 Gimbel and Neu­hann 7 list 20 potential benefits of capsulorhexis.

Harris and Specht8 reported six cases of total zonu­lar rupture during attempted external expression with an intact capsulorhexis. Because of the capsulorhexis' taut edge, external expression should not be used. Hydroexpression and viscoexpression rely on the buildup of fluid or viscoelastic pressure behind the

LP HM CF 20/200 20/120 20/80 20/60 20/40 20/30 20/20

Visual Acuity

nucleus to dislocate it forward into the anterior cham­ber. With these techniques, no force is placed on the zonule, making safe nucleus delivery possible. Thim and coauthors4 report the successful use of hydroex­pression in 26 consecutive cases, and Pande9 had two nuclear-delivery-related complications in 210 cases.

The success rate of capsulorhexis in our series was lower than others reported in the literature10 because it included the surgeon's learning curve; the rate of successful capsulorhexis improved from 68% in the first 50 cases to 96% in the final 50. In addition, many eyes had advanced cataracts, with 39.5% having a preoperative acuity of counts fingers or worse. In white, milky mature cataracts, two of nine capsula­rhexes were successful. Apart from poor visibility, the main reason for unsuccessful capsulorhexis was fail­ure to maintain a deep anterior chamber.

Hydrodissection was performed before viscoex­pression in all cases. If a track is not made between the cortex and the capsule using balanced salt solution, it is unlikely the viscoelastic will pass successfully be­hind the nucleus. Hydrodissection is not always achieved at first attempt. In some cases, several at­tempts must be made before the wave of hydrodissec­tion is seen passing behind the nucleus. In very dense cataracts, it is not possible to see this wave and hy­drodissection is continued until the nucleus bulges forward slightly.

The goal of this technique is to create an initial hydrodissection wave of 30% (L. Corydon, M.D., per­sonal communication, May 1992). The Healon will then preferentially accumulate behind the upper pole of the nucleus, causing the upper pole to dislocate forward first. If a 100% hydrodissection is performed, the Healon immediately tracks inferiorly and will sometimes result in the lower pole dislocating before the upper pole.

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Table 1. Complications.

CCC Visual Acuity Nucleus Size

Patient Density (mm) Preop Postop IOL Complication Cause

1 ++ 5.0 20/120 20/60 PC Iris sphincter tear, anterior Cannula removed from eye with hook capsule tear pointing posteriorly

2 +++ 6.0 CF 20/20 PC Anterior capsule tear, Cannula removed from eye with hook superior zonule rupture, pointing posteriorly vitreous loss

3 ++++ 4.5 CF 20/30 PC Superior zonule rupture, Attempted nucleus delivery with vitreous loss Rycroft cannula after unsuccessful

viscoexpression

4 ++ 5.0 20/60 20/30 PC Superior zonule rupture Attempted nucleus delivery with Rycroft cannula after unsuccessful viscoexpression

5 +++ 4.5 20/120 20/60 AC Inferior zonule rupture Viscoexpression with small capsulorhexis, large nucleus

6 ++ 4.5 20/80 20/30 PC Inferior zonule rupture Viscoexpression with small capsulorhexis, large nucleus

7 ++ 5.0 CF 20/20 PC Posterior capsule rupture During I/A

VA = visual acuity; CF = counts fingers; PC = posterior chamber; AC = anterior chamber

Although the intention was only to create a 30% hydrodissection, in many cases there was an immedi­ate 100% hydrodissection; in nine, immediate hydro­expression of the nucleus occurred. The size of the capsulorhexis determines whether initial hydrodissec­tion will result in hydroexpression. In the latter part of the series, as the surgeon's capsulorhexis skills im­proved, the capsulorhexis was 6 mm rather than 5 mm; it is in these cases that hydroexpression occurred.

Viscoexpression was successful in only 87% of eyes. It failed when a wave of hydrodissection could not be established and when capsulorhexis diameter was different from nucleus diameter. Many eyes had a pupil of 5 mm or less. If the capsulorhexis is 5 mm or less and there is a large nucleus, viscoexpression is not always successful. In these eyes, it is necessary to

make relieving incisions at 10 o'clock and 2 o'clock in the capsular edge, allowing for conventional expres­sion or vectis extraction of the nucleus.

In their initial description of viscoexpression, Cory­don and Thim3 describe using Healon to dislocate the upper and lower poles of the nucleus into the anterior chamber. When this technique was used, several cases required a second tube of Healon. The lower pole of the nucleus can be physically dislocated forward using the bent cannula. Corydon and Thim3 describe using an 18-gauge cannula and later a disposable 25-gauge cannula.

When the surgeon in the present study used a 25-gauge cannula, he found it easy to inject a whole syringe of viscoelastic quickly, and a second tube was often required. Although the 30-gauge cannula re-

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CF 20/200 20/120 20/80 20/60 20/40 20/30 20/20 20/15

Visual Acuitv

Fig. 2. (Burton) Best corrected visual acuity two months postoperatively.

J CATARACT REFRACT SURG-VOL 21, MAY 1995 299

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Fig. 3. (Burton) Astigmatism at two months. " .0 E :J z

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suited in a slower, more controlled delivery of the viscoelastic, viscoexpression was easily achieved. M­ter learning the technique, the surgeon found a single 0.5 ml tube of Healon sufficient for capsulorhexis, viscoexpression, and intraocular lens insertion in 90% of cases.

There is a theoretical risk of damage to the endo­thelium as the nucleus is pulled out of the anterior chamber on the end of the U-shaped cannula. In this series of 200 patients, there were no cases of corneal decompensation because during capsulorhexis, the an­terior chamber is filled with Healon, which coats the endothelium and protects it from damage as the nu­cleus is extracted. To establish that there was no significant corneal damage, a study with preoperative and postoperative endothelial cell counts would be required.

The main complication in this series was zonular rupture (n = 5). In one eye, rupture occurred when the cannula was removed with the hook pointing posteri­orly. In two eyes, superior zonular rupture occurred while the surgeon was trying to physically dislocate the upper pole of the nucleus after unsuccessful vis­coexpression. This technique had a complication rate of 13.3% and should not be used as it puts undue stress on the zonule; instead, relieving incisions in the ante­rior capsule should be made. Only two cases of zonu­lar rupture occurred during viscoexpression; in both, capsulorhexis size was 5 mm or less, a finding similar to that of Thim and coauthors. 6 Capsulorhexis position was also eccentric superiorly in these cases. In both eyes, the upper pole was successfully dislocated for­ward but during the dislocation of the lower pole inferiorly, the inferior zonule ruptured.

There were no complications when the capsula­rhexis was 6 mm or larger. We now think this is the best diameter, although during the learning curve of capsulorhexis, the larger the size, the more likely a radial extension is to occur.

0 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 Astigmatism (D)

The fear that the passage of a cannula behind the nucleus would rupture the capsule was unfounded. The one case of posterior capsular rupture occurred during II A in a patient who had a successful visco­expression. Irrigation and aspiration with an intact capsulorhexis are easier than with a beer-can cap­sulotomy, particularly with sutures preplaced to give a deep anterior chamber similar to that found in phacoemulsification.

Limbal sections cause acceptable levels of astigma­tism, with 94% having 2 diopters or less. The visual results were good, with poor results explained by pre-existing macula disease.

Viscoexpression is a safe technique in extracapsular surgery if a capsulorhexis larger than 5 mm is achieved. We have found it the ideal technique to complete the transition from extracapsular surgery to phacoemulsification because it helps the surgeon mas­ter the following skills: scleral incisions, capsula­rhexis, hydrodissection, viscoexpression, I/ A with an intact capsulorhexis, and lens insertion in the capsular bag.

REFERENCES

1. Assia EI, Castaneda VE, Legler UFC, et al. Studies on cataract surgery and intraocular lenses at the Center for Intraocular Lens Research. Ophthalmology Clin North Am 1991; 4(2):251-266

2. Thim K, Krag S, Corydon L. Stretching capacity of capsulorhexis and nucleus delivery. J Cataract Refract Surg 1991; 17:27-31

3. Corydon L, Thim K. Continuous circular capsulorhexis and nucleus delivery in planned extracapsular cataract extraction. J Cataract Refract Surg 1991; 17:628-632

4. Thim K, Krag S, Corydon L. Capsulorhexis and nu­cleus expression. Eur J Implant Refract Surg 1990; 2:37-41

5. Krag S, Thim K, Corydon L. Strength of the lens capsule during hydroexpression of the nucleus. J Cata­ract Refract Surg 1993; 19:205-208

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6. Thim K, Krag S, Corydon L. Hydroexpression and viscoexpression of the nucleus through a continuous circular capsulorhexis. J Cataract Refract Surg 1993; 19:209-212

7. Gimbel HV, Neuhann T. Development, advantages, and methods of the continuous circular capsulorhexis technique. J Cataract Refract Surg 1990; 16:31-37

8. Harris DJ Jr, Specht CS. Intracapsular lens delivery

during attempted extracapsular cataract extraction; as­sociation with capsulorrhexis. Ophthalmology 1991; 98:623-627

9. Pande M. Continuous curvilinear (circular) capsulorhexis and planned extracapsular cataract extraction-are they compatible? Br J Ophthalmol1993; 77:152-157

10. Lee CP. Capsulorhexis-a 5-year experience. Eur J Implant Refract Surg 1990; 2:27-31

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