'Can-opener' Extracapsular Cataract Extraction: Are Postoperative Mydriatics Necessary?

P.P. KEARNS, L. KAYE-WILSON and G.I.S. MACKINTOSH

Princess A/exandra Eye Pavilion, Cha/mers St., Edinburgh EH39HA

OBJECTIVES: To determine: (1) the ineidenee ofiridoeapsular and iridophakie adhesions foUow­ing 'ean-opener' eapsulotomy eataraet extraetion and (2) whether routine postoperative dilation alters the ineidenee of adhesions or affeets ultimate pupil shape and dilation. STUDY DESIGN: Retrospeetive study. SETTING: Ophthalmie out-patient department, Prineess Alexandra Eye Pavilion, Royal Infirmary of Edinburgh. PATIENTS: AU patients seen in out-patient elinie over a 3-month period who had previously undergone uneomplieated 'ean-opener' eataraet extraetion and whose eyes were now quiet. MAIN OUTCOME MEASURES: Ineidenee of iridoeapsular/ iridophakie adhesions, pupil shape and response to mydriaties. Also, whether mydriaties were used postoperatively. RESULTS: Adhesions oeeurred in 29% of eyes and were more eommon in those eyes treated with mydriaties postoperatively (0.01 > P > 0.001). Pupil distortion was also more eommon in this group (0.02 > P > 0.01), but subsequent pupillary dilation did not appear to be affeeted by postoperative mydriatie treatment. CONCLUSIONS: Iridoeapsular and irido­phakie adhesions oeeur in a signifieant number of eyes foUowing 'ean-opener' eapsulotomy extra­eapsular eataraet extraetion. However, they appear to be relatively benign. The routine post­operative use ofmydriaties is unneeessary.

Keywords: Extraeapsular eataraet extraetion; Adhesions; Mydriaties

INTRODUCTION

In the last decade extracapsular cataract extraction has largely replaced intracapsular surgery. InitiaIly, most surgeons performed so-called 'can­opener' capsulotomy with sulcus fixation of the in­traocular lens (lOL) [1]. A large, round anterior cap­sulotomy is fashioned by multiple needle-point per­forations. However, with time, concern began to be voiced as to the wisdom of sulcus fixation [2] and many began to turn to 'in-the-bag' implantation. The 'intercapsular' or envelope capsulotomy became the favoured technique for capsular fixation of the IOL. This involves making a single incision in the anterior capsule, performing lens extraction and irrigation/aspiration of lens matter through this opening and only enlarging the capsulotomy once the intraocular lens has been inserted 'in-the-bag'. As weIl as the theoretical safety of 'in-the-bag' com­pared with sulcus fixation, it has been claimed that the former is less damaging to the corneal endothe-

Correspondence to: Dr Kearns.

0955-3681/92/010015+04 $03.00/0 © 1992 Bailliere Tindall

lium, as irrigation/aspiration is carried out under the protective cover ofthe anterior lens capsule [4].

Despite the popularity of the intercapsular tech­nique, with placement of the IOL in the capsular bag, it is undoubtedly technically more difficult than 'can-opener' capsulotomy with sulcus fixation. A specific objection to the intercapsular technique raised recently has been the incidence of adhesions developing between anterior capsular remnants and either the posterior capsule, the IOL or the iris, resulting in pupil distortion, IOL decentring or poor pupillary dilation [5-7]. Some have advocated reverting to 'can-opener' capsulotomy with sulcus fixation since the intercapsular technique is only theoretically advantageous, is technically more dif­ficult and prone to more complications [7].

These reports, however, do not make clear the clinical significance of these adhesions, and in par­ticular do not comment on what effect, if any, they have on pupillary dilation, and whether the use of postoperative mydriatics influences their occur­rence. Following Dhillon's report [5], a subsequent group of patients undergoing intercapsular surgery was not dilated postoperatively and the incidence of

Eur J /mp/ant Re' Surg, Vo/4, March 1992

16

adhesions dropped significantly (unpublished data). Moreover, we were unable to find any reports in the literature regarding the incidence of such compli­cations in 'can-opener' capsulotomy, with the single exception of the study by Rosen et al. [7], in which no details were given on the use of postoperative mydriatics.

We therefore carried out this study to answer the following questions:

(1) what is the incidence of iridocapsular/ iridophakic adhesions following 'can-opener' capsu­lotomy;

(2) does the use of postoperative mydriatics affect the rate of occurrence of these adhesions;

(3) are these adhesions clinically significant, i.e. do they impair subsequent pupillary dilation?

METHODS

Over a 3-month period all patients who were attend­ing the out-patient department for routine post­operative follow up after cataract extraction and lens implant by 'can-opener' sulcus fixation tech­nique were examined by one ofus (PPK). In all cases a standard surgical technique was employed. After creating a conjunctival fiap (limbal or fornix based), a partial thickness posterior limbal ab externo in­cision was made. Through a small stab incision in the wound a curved cystotome needle was intro­duced into the anterior chamber. A 'can-opener' cap­sulotomy, as large as the pupillary diameter would allow, was created under Helonid. Following hydro­dissection and expression of the nucleus, irrigation and aspiration of corticallens matter was performed with either a MacIntyre or Simcoe cannula. A Sinsky 6mm optic posterior chamber IOL with 10° forward angulation of haptics (lOLAB G707G) was introduced and dialIed into the ciliary sulcus in all cases, with no attempt made to place the IOL 'in-the­bag'. The wound was then sutured with either inter­rupted virgin silk or a continuous 'bootlace' nylon suture. For the purposes of the study the following patients were excluded: patients with any pre­operative history ofuveitis or previous surgery, any variation in standard technique (e.g. sector or peri­pheral iridectomy, sphincterotomy), intraoperative complications (e.g. vitreous loss), severe post­operative uveitis or endophthalmitis, or hyphaema. Any eye that was not entirely quiet and off topical steroid treatment was also excluded. The following data were recorded; name, date ofbirth, date of oper­ation, surgeon, whether postoperative dilating drops were prescribed, duration of use of steroids post­operatively, date of current examination and period since operation. The eyes were then examined and

P.P. Kearns et si.

the following features were noted; visual acuity and shape and size of the pupil (either round or dis­torted). All patients were then dilated by a single drop of tropicamide 1% and phenylephrine 10%, and then further examined in 45 minutes to an hour's time. Pupil dilation was noted and classified accord­ing to the percentage increase in pupil diameter. A Goldman 3 mirror lens was used to examine both the anterior chamber drainage angle and the anterior capsular remnant, IOL and posterior surface of the iris in the pupil area. The presence of angle synechiae and of iridocapsular and iridophakic ad­hesions were recorded.

RESULTS

A total of 86 patients were studied. Forty-two were treated postoperatively with mydriatics and ster­oids, 44 were treated with steroids alone. Operations were carried out by a total of six different surgeons, all of whom were experienced junior members of staff. Each operated on patients of a number of different consultants, each ofwhom had a particular policy as to the use ofpostoperative mydriatics. The use of postoperative mydriatics was determined by which consultant the patient was registered under, not by the surgeon or any specific clinical indication, and therefore could be considered to be random.

The average length of time for which mydriatics were used was 6 weeks. Most were on steroids for between 6 weeks and 6 months. The average time between operation and examination was 14 months (range 4 to 68 months). The long period of follow-up in a number of eyes is explained by patients attend­ing the clinic for treatment for the fellow eye, in most cases for a second cataract extraction. Follow­ing uncomplicated surgery patients were discharged at about 1 year.

Figure 1 shows the proportion of patients whose undilated pupil was distorted. Figure 2 shows the effect of dilation with tropicamide and phenyleph­rine prior to examination on the pupil. Out of 86

Fig. 1 Pupil shape (undilated)

Eur J /mp/ant Ret Surg, Vo/4, March 1992

'Can-opener' ECCE

< 50% increose in pupil diameter 7.98%

17

2 .29% Fixed in dilation

·,,,., , ~' .....•.•..... ' .. ' •. '." ...... ," ... , .. . ~ i

• 27.92%

> 50% increase in pupil diameter

61.81% ~ ~~

>100% increose in pupil diameter

Fig. 2 Response of pupil to tropicamide and phenylephrine

patients iridocapsular/iridophakic adhesions were found in 25 (29%) and peripheral anterior synechiae in 31 (36%). The average final visual acuity was slightly better than 6/9.

The effects of postoperative pupil dilation are shown in Tables 1-4.

Table 1 Effect of postoperative dilating drops on ultimate pupil shape

Patients treated with mydriatics

Patients treated without mydriatics

Roundpupil

21

32

Distorted pupil

23

10

Chi-squared test, Yates' correction; 0.02 > P > 0.01.

Table 2 Pupillary response to tropicamide and phenylephrine

Increase in pupillary diameter Fixed in

> 100% > 50% < 50% dilation Patients treated with

mydriatics 28 11 2 1 Patients treated without

mydriatics 25 13 5 1

Chi-squared test; P > 0.5.

Table 3 Incidence of adhesions

None Adhesions present

Patients treated with mydriatic

Patients treated without mydriatic

25

36

19

6

Chi-squared, Yates' correction; 0.01> P > 0.001.

Table 4 Incidence of peripheral anterior synechiae asso­ciated with IOL haptic in the ciliary sulcus

Patients treated with mydriatic Patients treated without mydriatic

None 29 26

Chi-squared test, Yates' correction; 0.5 > P > 0.1.

Eur J /mp/ant Re' Surg, Vo/4, March 1992

PA.S. present

13 18

DISCUSSION

The overall incidence of adhesions (29%) was in the same order as that reported with intercapsular oper­ations. Peripheral anterior synechiae (PAS) were in all cases associated with the IOL haptic. This associ­ation has been observed previously [8]. These syne­chiae are caused by indentation of the iris root by the IOL haptic, fixed in the sulcus, causing localized iridocorneal contact. They are characteristically non-progressive, and are not associated with eleva­tion of intraocular pressure. They are associated with forward angulation of the haptic, the configur­ation of the lenses used in our centre. The signifi­cance of these is therefore unclear, but should perhaps be borne in mind when implanting intra­ocular lenses in eyes with areas ofpre-existing angle closure.

The routine use of mydriatics postoperatively made pupil distortion more likely and increased the incidence of adhesions. However, it did not affect subsequent pupil dilation (Table 2), which would seem to be the only point of real practical import­ance.

Although a number of different surgeons carried out the operations, the results, when analysed on an individual basis, were similar.

In summary, although iridocapsular and irido­phakic adhesions occur in a significant number of 'can-opener' cataract extractions, and postoperative pupillary dilation increases this number, they seem to have no deleterious effects. 'Can-opener' compares weIl in this respect with the intercapsular technique (Raines et al. reported a 46% incidence of adhesions in the latter) and postoperative mydriatics seem unnecessary. Various techniques of capsulorhexis are becoming increasingly used and are likely to be associated with far more reliable capsular fixation and a much lower incidence of iridocapsular ad­hesions than either the 'can-opener' or intercapsular techniques [9]. However, these latter techniques will always be required in a proportion of patients and therefore the findings ofthis study are ofpracti­cal importance to today's cataract surgeons.

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REFERENCES

1 SP Shearing. The Shearing posterior chamber lens and extra­capsular surgery. In ES Rosen, W Haining, EJ Arnot, Intra­ocular Lens Implantation. The CV Mosby Company, St. Louis 1984: 366-375. '

2 JB Crawford. A histopathological study ofthe Shearing intra­ocular lens in the posterior chamber. Am. J. Ophthalmol. 1981; 91(4): 458-461. '

3 AGaland, R Van Oye, C Budo, F Goes, B Foets. Results of implantation in the capsular bag. A short term review of 1588 cases. Trans. Ophthalmol. Soc. U.K., 1985; 104: 563-566.

4 J Patel, DJ Apple, SO Hansen et al. Protective effect of the anterior lens capsule during extracapsular cataract extrac­tion: Part 11. Preliminary results of clinical study. Ophthal­mol., 1989; 96(5): 589-602.

P.P. Kearns et al.

5 B Dhillon, G Maclntosh, V Khanna, BW Fleck. Iris/Anterior capsule adhesions and capsule opacification in endocapsular extraction. Implants in Ophthalmology (Singapore), 3(1): 27.

6 MF Raines, p. Corridan, EC O'Neill. Posterior synechiae in intercapsular cataract surgery. Ophthalmie Surg., 1989; 20(4): 245-249.

7 PH Rosen, JM Twomey, CM. Kirkness. Endocapsular cataract extraction. Eye, 1989; 3: 672-677.

8 RB Evans. Peripheral anterior synechiae overlying the hap­tics of posterior chamber lenses. Occurrence and natural history. Ophthalmol. , 1990; 97(4): 415-423.

9 EI Assia, DJ Apple, JC Tsai, ES Lim. The elastic properties of the lens capsule in capsulorrhexis. Am. J . OphthalmoZ., 1991; 111: 628-632.

Reeeived April 1991

Eur J Implant Re! Surg, VOl4, March 1992