Reduced intraocular pressure after phacoemulsification and posterior chamber intraocular lens implantation

Claus E. Jahn, MD

ABSTRACT

Purpose: To ascertain whether phacoemulsification with posterior chamber intraoc­ular lens (IOL) implantation causes long-term reduction in intraocular pressure (lOP).

Setting: Private practice, Kempten, Germany.

Methods: Intraocular pressure was measured in both eyes of 120 consecutive patients who were unilaterally phakic after phacoemulsification a mean of 17 months ± 17 (SD) previously. Mean age of the 36 men and 84 women was 76 ± 10 years. Data were analyzed using binomial distribution and the Wilcoxon signed-rank test.

Results: The median ratio of lOP in the pseudophakic eye to lOP in the phakic eye was 0.83. The lOP was lower in the pseudophakic eye in 96 patients (80%). The median lOP was 12 mm Hg in the pseudophakic eyes and 14 mm Hg in the phakic eyes (P < .001). As measured by the interquartile range, lOP distribution was more centered in the pseudophakic than in the phakic eyes (3 versus 4). The lOP in the pseudophakic eyes remained lower to the last measurement, 5 years postopera­tively, and appeared to be independent of patient age. Lower lOP in the pseudophakic eye was consistently present in patients with higher lOP in the phakic eye (16 to 22 mm Hg).

Conclusion: Phacoemulsification with posterior chamber IOL implantation reduced lOP in most but not all patients with a preoperative lOP of 22 mm Hg or less. This reduction was maintained over several years, with the cause yet to be established. Lower lOP may decrease the risk of subsequent glaucomatous nerve damage in these patients. J Cataract Refract Surg 1997; 23:1260--1264

T he effect on intraocular pressure (lOP) of extra­

capsular cataract extraction (ECCE) with or with­

out posterior chamber intraocular lens (IOL) implanta­

tion is still controversial. Although some prospective studies have been done,l-4 most have been based on a

review of medical records.5-14 In addition, most exam­

ined the effect of ECCE with posterior chamber IOL implantation in glaucoma patients.3,5-10,12-14 These stud­

ies disagree; some found that the procedure lowers IOP1-7,12-14 and others that it has no detectable effect?-10

The difference in findings may have been the result of

the heterogeneity of the cohorts.

Reprint requests to Claus E. Jahn, MD, Bodmanstrafe 8, 87435 Kempten, Germany.

Based on the literature and unsystematic observa­

tion of several thousand patients who had phacoemul-

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lOP IN PSEUDOPHAKIA

sification with posterior chamber 10L implantation, I hypothesized that the procedure often lowers lOP in patients with senile cataract alone or combined with glaucoma. This study measured lOP over several years after phacoemulsification and posterior chamber lens implantation in patients with normal lOP not suffering from glaucoma. The goal was to determine whether the procedure lowers lOP and if so, how much and for how long.

Materials and Methods

The first consecutive 120 patients who had phaco­emulsification with posterior chamber 10L implanta­tion and who met the entry criteria were selected for the study. The order was exclusively determined by the timing of the follow-up appointment; thus, the cohort was considered to be representative.

All patients were unilaterally pseudophakic after having phacoemulsification with posterior chamber 10L implantation a mean of 17 months :±: 17 (SO) previously (range 2 to 69 months). Mean age of the 36 men and 84 women was 76 :±: 10 years (range 53 to 97 years). Of the pseudophakic eyes, 67 (56%) were right and 53 (44%) were left eyes; the difference was not significant.

Inclusion criteria were an lOP of22 mm Hg or less preoperatively and at all visits after 2 months postop­eratively, wide angles, a normal optic nerve head, no glaucoma or history of glaucoma treatment, and no other intraocular surgery in either eye. Excluded were patients with diabetic retinopathy or central venous occlusion.

Phacoemulsification was done using a 3.0 mm superior scleral approach (n = 40) or a scleral tunnel (n = 80) enlarged to 6.0 mm for in-the-bag insertion of a one-piece or three-piece poly(methyl methacrylate) posterior chamber 101. The median ratio ofIOP in the pseudophakic eye to lOP in the phakic eye did not differ significantly between the two groups (0.84 versus 0.82). Emulsification of the nucleus was performed within the bag, with the posterior capsule intact in all eyes. No cyclodialysis or filtering bleb occurred.

To negate the influence of diurnal variation, one lOP measurement was taken by Goldmann applana­tion tonometry in both eyes at the same visit with the pupils undilated. To ascertain whether phacoemulsi-

fication with posterior chamber 10L implantation low­ered lOp, the ratio of lOP in the pseudophakic eye to lOP in the phakic eye was determined.

To test the methodology, the ratio of lOP in one eye to that in the fellow eye was determined in 100 consecutive patients who were phakic in both eyes but had senile cataract in one eye; the ratio was 1.0 :±: 0.1. The ratio distribution was symmetrical around 1.0 (Figure 1), indicating that in general, the presence of a cataract did not cause a difference in lOP between the two eyes of an individual patient. Other than being bilaterally phakic, these patients met the study's inclu­sion criteria.

Surgical analysis was done using binomial distribu­tion and the Wilcoxon signed-rank test. 15

Results In 96 patients (80%), the ratio of lOP in the

pseudophakic eye to lOP in the phakic eye was less than 1.0, with the lOP lower in the pseudophakic eye (Figure 2). In 18 patients (15%), there was no differ­ence in lOP between eyes. In 6 patients (5%), lOP in the pseudophakic eye was higher than in the fellow phakic eye and the ratio ofIOP was more than 1.0.

For all eyes, the median ratio of lOP in the pseudophakic eye to lOP in the phakic eye was 0.83. The estilVated probability that phacoemulsification with posterior chamber 10L implantation would lower lOP was P = 0.8 (99% confidence limits: 0.71 < P < .89).

•

•

~ ----80 100

Figure 1. (Jahn) Percentile plot of the ratio of lOP in one phakic

eye to lOP in the fellow phakic eye.

J CATARACT REFRACT SURG-VOL 23, OCTOBER 1997 1261

lOP IN PSEUDOPHAKIA

~ . .,

-. -40 60 80 100

Percentile

Figure 2. (Jahn) Percentile plot of the ratio of lOP in the pseudophakic eyes to lOP in the phakic eyes.

Intraocular pressure in pseudophakic eyes could be as much as 40% lower than in the fellow phakic eyes; in about two-thirds of patients, the lOP in the pseudo­phakic eye was up to 20% lower than in the phakic eye. The median lOP in the pseudophakic eyes was lower than that in the phakic eyes (12 versus 14 mm Hg).

Figure 3 shows the lOP distribution for the pseudophakic and phakic eyes. The distribution for the pseudophakic eyes was over a smaller range than that for the phakic eyes. The interquartile range was 3 and 4 mm Hg, respectively.

Figure 4 shows the distribution of lOP ratios for each pair of eyes over time since phacoemulsification. Ratios smaller than 1.0 were the rule up to 63 months postoperatively. No patient with an lOP of 16 to 22 mm Hg in the phakic eye had a higher lOP in the pseudophakic eye (Figure 5). The lOP ratio was inde­pendent of patient age (Figure 6).

Discussion

Most patients in this study had lower lOP in the pseudophakic than in the phakic eye. This finding is unexpected because these patients had wide angles. The most likely explanation is that phacoemulsification with IOL implantation decreased the lOP in these eyes. Although the difference between eyes was observed over the range of lOP measured, it appeared to be more consistently present in the higher range of lOP. It would be interesting to see whether this is also true in patients with an lOP above 22 mm Hg. These findings

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Figure 3. (Jahn) Frequency distribution of lOP in pseudophakic (top) and phakic (bottom) eyes.

Figure 4. (Jahn) Scattergram of the ratio of lOP in the pseudophakic eyes to lOP in the phakic eyes in relation to time since surgery.

agree with those of earlier studies that evaluated the influence of conventional ECCE and phacoemulsifi­cation with posterior chamber IOL implantation in eyes without glaucoma. 1,11

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lOP IN PSEUDOPHAKIA

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Figure 5. (Jahn) Scattergram of the ratio of lOP in the pseudophakic eyes to lOP in the phakic eyes in relation to lOP in the phakic eye.

In most cases, the ratio ofIOP in the pseudophakic eye to lOP in the phakic eye was less than 1.0 over 5 years postoperatively, suggesting that phacoemulsifi­cation with posterior chamber 10L implantation lowers lOP for a long time. The difference seemed to become smaller over time, as has been reported after ECCE with posterior chamber 10L implantation.2 If one used the difference in lOP to estimate the change in lOP caused by phacoemulsification and 10L implantation, lOP reductions between 20 and 40% could be expected in half the cases.

Some authors4,12 have suggested that deepening the

anterior chamber decreases lOP after ECCE with posterior chamber lens implantation. However, this

hypothesis remains to be proven. If the reduction in lOP has a physiological effect, it

would be that of reducing the risk of the pseudophakic eye developing glaucomatous nerve damage16 over a long period. This also remains to be established.

There appears to be no reason patients with glau­coma would not benefit from this reduction in lOP. Although research shows that ECCE lowers lOP in

patients with glaucoma, some require further drug or surgical treatment.3-9,12,13

References

1. Hansen TE, Naeser K, Rask KL. A prospective study of intraocular pressure four months after extracapsular cataract extraction with implantation of posterior cham­ber lenses. ] Cataract Refract Surg 1987; 13:35-38

2. Hansen TE, Naeser K, Nilsen NE. Intraocular pressure 2Y2 years after extracapsular cataract extraction and

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55 60 65 70 75 80 85 90 95 100

Patient Age (Years)

Figure 6. (Jahn) Scattergram of the ratio of lOP in the pseudophakic eyes to lOP in the phakic eyes in relation to patient age.

sulcus implantation of posterior chamber intraocular lens. Acta Ophthalmol 1991; 69:225-228

3. Wishart PK, Atkinson PL. Extracapsular cataract extrac­tion and posterior chamber lens implantation in patients with primary chronic angle-closure glaucoma: effect on intraocular pressure control. Eye 1989; 3:706-712

4. Lucas B, Kruger H, Bake W Retropupillare Linsen bei Glaukom: Vorderkammertiefe, Druckverhalten Medi­kation pra- und postoperativ. Fortschr Ophthalmol 1986; 83:214-216

5. Kooner KS, Dulaney DO, Zimmerman T]. Intraocular pressure following ECCE and IOL implantation in patients with glaucoma. Ophthalmic Surg 1988; 19:570-575

6. Handa], Henry ]c, Krupin T, Keates E. Extracapsular cataract extraction with posterior chamber lens implan­tation in patients with glaucoma. Arch Ophthalmol 1987; 105:765-769

7. Calissendorff BM, Hamberg-Nystrom H. Pressure con­trol in glaucoma patients after cataract surgery with intraocular lens. Eur J Ophthalmol 1992; 2:163-168

8. McGuigan LJB, Gottsch J, Stark WJ, et al. Extracapsular cataract extraction and posterior chamber lens implanta­tion in eyes with preexisting glaucoma. Arch Ophthalmol 1986; 104:1301-1308

9. Savage JA, Thomas]V, Belcher CD III, Simmons RJ. Extracapsular cataract extraction and posterior chamber intraocular lens implantation in glaucomatous eyes. Ophthalmology 1985; 92:1506-1516

lO. Radius RL, Schultz K, Sobocinski K, et al. Pseudophakia and intraocular pressure. Am J Ophthalmol 1984; 97:738-742

11. Kooner KS, Cooksey ]C, Perry P, Zimmerman T]. Intraocular pressure following ECCE, phacoemul­sification, and PC-IOL implantation. Ophthalmic Surg 1988; 19:643-646

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lOP IN PSEUDOPHAKIA

12. Steuhl KP, Marahrens P, Frohn C, Frohn A. Intraocular pressure and anterior chamber depth before and after extracapsular cataract extraction with posterior chamber lens implantation. Ophthalmic Surg 1992; 23:233-237

13. Kamman J, Niickel A, LUcking W, Wetzel W. Hinter­kammerlinsen-Implantation bei Glaukom. Fortschr Ophthalmol 1985; 82:183-185

14. Payer H, Payer G. Intraokulare Drucksenkung nach Einsetzen von nach hinten gewinkelten Ziliarkorper­gestUtzten Sienskey-Hinterkarnmerlinsen in normotone Augen. Klin Monatsbl Augenheilkd 1983; 183:381-383

15. Snedecor Gw, Cochran WG. Statistical Methods, 7th ed. Ames, lA, Iowa State University Press, 1980; 83-143

16. Sommer A. Intraocular pressure and glaucoma (edito­rial). Am J Ophthalmol1989; 107:186-188

Presented in part at the annual meeting of the German Ophthalmologi­cal Society, Mannheim, September 1994, and the JERMOV meeting, Montpellier, France, October 1994.

The author has no proprietary interest in any material or method presented.

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