Corneal Endothelial Cell Density After Complicated Cataract Surgery and Implantation of an Anterior

Chamber Intraocular Lens MERVI A. BERGMAN, HEIKKI NIEMINEN and LEILA T. LAATIKAINEN

Department 0' Ophtha/m%gy, University 0' Ou/u, Ou/u, Fin/and

OBJECTIVE: To compare corneal endothelial cell densities in eyes with a semifiexible open-loop anterior chamber intraocular lens (AC-IOL) with those in unoperated fellow eyes or in fellow eyes having a posterior chamber intraocular lens (PC-IOL). STUDY DESIGN AND SETTING: During the period January 1988 to August 1990 48 AC-IOLs were implanted in eyes in which either an intracapsular cataract extraction was performed or during an extracapsular extraction posterior capsular support was lost. The corneal endothelial cells of 25 of the 48 patients were photo­graphed using a specular microscope 7 to 37 months (median 22) postoperatively. P ATIENTS: The mean age of the patients was 72.6 years (range 39 to 86). In 16 cases (group A) the fellow eye was phakic, in nine cases (group B) the fellow eye had a PC-IOL implanted after uncomplicated surgery. RESULTS: In group A the mean cell densities in the operated and unoperated eye were 1726 and 23211mm2

, respectively (P < 0.001), in group B the mean cell densities in eyes with an AC­IOL and a PC-IOL were 1485 and 1900/mm2

, respectively (P < 0.05). The presence of glaucoma, exfoliation syndrome or anterior vitrectomy did not reduce the mean cell density. CON­CLUSIONS: Although the corneal endothelial cell densities were lower in eyes with an AC-IOL than in unoperated fellow eyes or in fellow eyes with uncomplicated cataract surgery and a PC­IOL, the risk of corneal decompensation seems to be small, and therefore the use of an open-loop semifiexible AC-IOL in complicated age-related cataract extraction is justified.

Keywords: Cataract surgery; Anterior chamber intraocular lens; Corneal endothelial cells; Specu­lar microscopy.

INTRODUCTION

In the 1980s pseudophakic bullous keratopathy became the most common indication for penetrating keratoplasty in many centres, and the most common type of intraocular lens associated with bullous keratopathy was a closed-Ioop semiflexible anterior chamber intraocular lens (AC-IOL) [1]. Therefore the use of an AC-IOL was almost abandoned and replaced with a posterior chamber intraocular lens (PC-IOL) implantation. In conditions such as sub-. luxation of the lens or wide rupture of the posterior capsule or zonules safe insertion of a PC-IOL may not be possible without fixation of the lens with sutures. This procecure is more complex, however, it involves more manipulation and requires more sur-

Correspondence to: Leila Laatikainen, M.D., Department ofOph­thalmology, Oulu University Hospital, SF-90220 Oulu, Finland.

0955-3681/93/040237+05 $08.00/0 © 1993 Bailliere Tindall

gical time than implantation of an AC-IOL, and various short- and long-term complications possibly related to IOL suture have been presented [2-5]. All problems related to trans-sclerally fixated posterior chamber lenses may not yet be known. Therefore, implantation of an AC-IOL may still be a good choice in many complicated cases.

It is estimated that about 5% of all IOLs implanted in Finland are anterior chamber lenses. In most cases an AC-IOL is used because of zonular or posterior capsular break. One reason for the occurrence of these intraoperative complications is the high frequency of exfoliation syndrome in the Finnish cataract population [6]. In this study we compared endothelial cell densities in 25 eyes having had an open-Ioop semiflexible AC-IOL for 7 to 37 months (median 22 months) to those in the

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fellow eyes which were either phakic or had a PC­IOL after uncomplicated cataract surgery 0 to 37 months (median 22 months) previously.

PATIENTS AND METHODS

During the period of January 1988 to August 1990, 48 AC-IOLs were implanted during primary catar­act surgery. In 25 of these patients, specular pho­tography of the central cornea of both eyes was per­formed 7 to 37 months (median 22) after surgery. In 16 cases (group A) the fellow eye had had no cataract surgery, but trabeculectomy had been performed on three eyes. In ni ne cases (group B) the fellow eye had a PC-IOL.

The operations were performed by a number of surgeons, some of them in training. The AC-IOL used was a semifiexible one-piece open-Ioop lens (the Symfiex™ AC-Iens, Pharmacia, Groningen, The Netherlands) with the diameter of 13.75mm. In 10 eyes cataract extraction was intracapsular (in three cases planned, in seven cases unintentional), in 15 eyes extracapsular. All the latter cases were compli­cated by a wide rupture of the posterior capsule or zonules. Anterior vitrectomy with sponge and scis­sors or a vitrectomy instrument was performed in 15 cases (60%).

The camera used for specular photography was a Konan specular microscope Sp-5500. For each eye 2-5 photographs were taken of the central cornea, and the photographs with the clearest cell bound­aries were selected for printing and analysis. Kodak T-max 100 film was used. The image on the negative was x40. The final magnification on the paper print was x 240. The number of cells was counted three times in an area corresponding to 0.01 mm2 of cor­nea, and the average was taken as the cell density. The percentage of hexagonal cells (an index of pleo­morphism) was counted.

STATISTICAL METHODS

Mean, standard deviation (SD) and range are given for continuous variables, and median for time vari­ables (age, follow-up period). 95% confidence inter­val is given for the cell counts in the various groups. Paired t-test is used for comparing the means ofthe cell counts in the two eyes of one person, for other comparisons the unpaired t-test is used. Correlation between the cell counts and the age or the follow-up period is tested with the Spearman correlation.

M.A. Bergman, H. Nieminen and L.T. Laatikainen

RESULTS

The mean age of the patients was 72.6 years (median 74, range 39-86),19 out ofthe 25 being 70 years of age or older. There was no significant corre­lation between the cell density and the age of the patients (Figs 1 and 2) nor between the cell density and the length of the follow-up period in any of the groups studied.

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3000

2750

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35 40 45 50 55 60 65 70 75 80 85 90

Age

• AC-tOl o Unoper.eye

Fig. 1 Endothelial cell density in the eyes with an anterior chamber intraocular lens (AC-IOLl and the fellow unoperated eyes in relation to the age of the patient. On three of the phakic eyes (marked with a diagonal) trabeculectomy had been per­formed

2600 • AC-IOl • o Pe-IOl 2400 0

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~ 2000 • u • '0 1800 0 0 O. 0 ID 1600 .!l 0 E 1400 • :> Z 1200 • • 1000

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Fig. 2 Endothelial cell density in the eyes with an anterior chamber intraocular lens (AC-IOLl and the fellow eyes with a posterior chamber intraocular lens (PC-IOLl in relation to the age of the patient

In group A the mean endothelial cell densities in the opera ted eye and the unoperated fellow eye were 1726 ± 513 (range 900-2767) and 2321 ± 406 (range 1667-3167) cells/mm2

, respectively (P < 0.001) (Table 1). In two patients the cell density was slightly (7-8%) greater in the operated eye, in one case both eyes had similar values and in the remain­ing 13 cases the opera ted eye had 8-54% less endo­thelial cells than the unoperated eye. In the phakic eyes, the lowest endothelial cell densities were found in eyes which had had a trabeculectomy (Fig. 1).

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Corneal endothelial cell denslty 239

Table 1 Endothelial cell densities in eyes with an anterior chamber intraocular lens (AC-IOL), in unoperated fellow eyes and in fellow eyes with a posterior chamber intraocular lens (PC-IOL)

Group Eye with AC-IOL Unoperated fellow eye Fellow eye with PC-IOL

* 95% confidence interval.

n

25 16 9

Mean 1639 2321 1900

In group B the mean endothelial cell densities in eyes with an AC-IOL and in eyes with a PC-IOL were 1485 ± 566 (range 850-2550) and 1900 ± 321 (range 1467-2416) cells/mm2

, respectively (P < 0.05) (Fig. 2). The follow-up time did not differ be­tween the groups (19.7 and 17.6 months on the aver­age, respectively). In three patients the cell count was slightly (5-8%) greater in the AC-IOL eye, in one case the densities were equal and in five cases the AC-IOL eye had 36-50% less cells than the fel­low eye with a PC-IOL.

Seven of 25 eyes (28%) with an AC-IOL had pri­mary chronic open-angle glaucoma. No difference was found in the mean endothelial cell densities be­tween glaucomatous (1557 ± 332 cells/mm2

) and non-glaucomatous (1671 ± 600 cells/mm2

) eyes. Exfoliation syndrome had been diagnosed in 15

eyes (60%). The endothelial cell density in eyes with AC-IOL and exfoliation syndrome (1630 ± 512 cells/ mm2) did not differ significantly from that in eyes with an AC-IOL and no exfoliation syndrome (1714 ± 504 cells/mm2

).

During cataract surgery anterior vitrectomy was performed in 15 eyes (60%). The me an endothelial cell density was greater in eyes having had an an­terior vitrectomy (1844 ± 493 cells/mm2

) than in eyes in which no vitrectomy was performed (1332 ± 457 cells/mm2

, P < 0.05). The me an percentage of hexagonal cells did not

differ in the various groups: 58 ± 12% (95% confi­dence interva154-63%) in eyes with an AC-IOL, 63 ± 9% (95% confidence interval 56-70%) in eyes with PC-IOL and 62 ± 11% (95% confidence interval 56-68%) in unoperated fellow eyes.

DISCUSSION

The number of endothelial cells in healthy eyes de­creases with age from about 4500 to 2000-2500 cells/mm2 at the age of 70 years and to less than 2000 after 70 years of age (7). In the present se ries the me an cell density in the unoperated eyes was 2320 cells/mm2 • Because of the small number of cases and the fairly narrow age range no correlation between cell density and age was found.

Reports on endothelial cell loss in cataract sur-

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sn 535 406 321

Cell density (cells/mm2)

Range 850-2767

1667-3167 1467-2416

95% Cl*

1419-1860 2104-2537 1653-2147

gery have been presented since the 1970s. Endo­thelial cell loss depends on the method of surgery, implant type and operative and postoperative com­plications. After intracapsular cataract extraction decline in endothelial cell density is more likely if operative or postoperative complications occur [8]. Implantation of an intraocular implant increases cell loss. In the early reports cell loss after intra­ocular implantation of iris-fixated or iridocapsular lenses was significant [9-13]. Kraff et al. (12) re­ported 13-15% cell loss after intracapsular extrac­tion or posterior chamber phacoemulsification with­out an IOL implantation and 16-21% cellioss after an anterior chamber, iris-fixated or posterior chamber IOL implantation. Both Kraff et al. (12) and Rao et al. (13) reported less cell loss after AC­IOL implantation than with other implants. Galin et al. (11) found that the decline essentially ceased at ab out three months after surgery whereas Rao et al. [13] and Liesegang et al. (14) noticed progressive cell loss even during the second year after surgery.

In the early studies the AC-IOLs used were rigid or semiflexible closed-Ioop lenses. It seems that the endothelial cell damage with implantation of an open-loop semiflexible AC-IOL is less. Stur [15] found 15% cell loss during the first year and a pre­sumptive 4% cell loss during every 3 years in the next decade. In the present series preoperative endo­thelial cell densities were not known because these are not routinely examined and AC-IOLs were mainly used after operative complications in patients originally selected for posterior chamber implantation. Comparison of the cell densities with those in the unoperated phakic eye showed that most patients had significantly less cells in the oper­ated eye and the eye with an AC-IOL had signifi­cantly less cells than the fellow eye with a PC-IOL. Until now no clinically significant corneal decom­pensation has occurred, however. We had no cases with suture fixated PC-IOL for comparison. It may well be that manipulation and increased surgical time required for suturing may have caused at least a similar degree of cell damage than insertion of an AC-IOL. During penetrating keratoplasty implan­tation of a Kelman-style AC-IOL was associated with similar [16] or less endothelial cell loss than implantation of a sutured PC-IOL [17].

240

In addition to physiological reduction by age and following intraocular surgery, the number of endo­thelial cells may be reduced in glaucomatous eyes [18, 19], in exfoliation syndrome [20, 21] and in chronic uveitis [22]. In the present series the endo­thelial cell densities in eyes with an AC-IOL did not differ between glaucomatous and non-glaucomatous eyes or between eyes with and without exfoliation syndrome. The lowest cell counts in the unoperated eyes were, however, seen in glaucomatous eyes which had had trabeculectomy corresponding with findings of Brooks and Gillies [19]. In these eyes the cell counts were similar to the mean values in eyes having an AC-IOL.

According to previous studies the average cell density which results in cornea I decomposition and bullous keratopathy is about 500 cells/mm2 [23-26]. In the present series four ofthe 25 eyes with an AC­IOL had 850-1000 cells/mm2 but until now no signs of bullous keratopathy have developed. Bates et al. [25] reported that corneal decompensation occurred at a mean time after complicated cataract surgery of 44.6 months, and at that time the endothelial cell density was 495 cells/mm2

. Two years post­operatively the mean cell density in eyes with com­plicated cataract extraction progressing to bullous keratopahy was 853 ± 452 cells/mm2 as compared with 2086 ± 648 cells/mm2 in eyes with uneventful per- and postoperative course. Accordingly, four of the 25 eyes with an AC-IOL in our series (16%) having less than 1000 cells/mm2 9 to 27 months postoperatively may be in danger of developing bul­lous keratopathy with time.

In addition to cell density, variation in the cell size (polymegathism) and shape (pleomorphism) seem to be important for the function of the endo­thelium [20, 27, 28]. Cheng [29] did not, however, find significant difference in cell morphology be­tween eyes developing bullous keratopathy and those that did not. In our series pleomorphism did not differ between the groups.

To conclude, the endothelial cell density observed in the present series of eyes with an AC-IOL after complicated cataract extraction justifies the use of open-Ioop semiflexible AC-IOLs in senile eyes if cap­sular support is lost but in younger patients the lens style may warrant more concern.

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