Effectiveness of the soft-shell technique in patients with Fuchs' endothelial dystrophy

ARTICLE

Effectiveness of the soft-shell technique in patients with Fuchs’ endothelial dystrophy Dorota Tarnawska, MD, Edward Wyl˛ega1a, MD, PhD

PURPOSE: To evaluate the protective ability of the soft-shell technique in patients with senile cataract and Fuchs’ dystrophy having phacoemulsification with intraocular lens (IOL) implantation. SETTING: Department of Ophthalmology, Railway Hospital, Katowice, Poland. METHODS: Sixty-one eyes of 54 patients (37 women, 17 men) with clinically confirmed Fuchs’ dystrophy and cataract had clear corneal phacoemulsification and implantation of an intracapsular posterior chamber IOL with sodium hyaluronate 1% (Healon) or chondroitin sulfate 4%–sodium hyaluronate 3% (Viscoat) in combination with sodium hyaluronate 1% (Provisc) in 1 package (DuoVisc). The central corneal thickness (CCT), measured with a Pocket Precision ultrasonic pachymeter (Quantel Medical, Inc.), was compared preoperatively and 1 day, 1 week, and 1 and 6 months postoperatively. RESULTS: The mean preoperative CCT was 549.5 mm G 29.3 (SD). The postoperative increase in CCT over preoperative pachymetry measurements remained statistically significant in both ophthalmic viscosurgical device groups throughout the entire follow-up, from the first day to the sixth month after surgery (P<.0001). The maximum increase in CCT in both groups was on the first postoperative day, and it was significantly higher in the Healon group. Six months postoperatively, patients in the Healon group had a significantly greater CCT increase (P Z .008). CONCLUSION: The soft-shell technique effectively protected the compromised endothelium in patients with Fuchs’ dystrophy, proving its advantages in eyes with moderately damaged endothelium. J Cataract Refract Surg 2007; 33:1907–1912 Q 2007 ASCRS and ESCRS

Fuchs’ dystrophy is an inherited disorder of unknown etiology in which the corneal endothelial cells develop morphological and functional abnormalities. Clinically, the disease progresses slowly over a period of 20 years or more from asymptomatic cornea guttata to corneal edema with decreased vision. Pathology studies suggest the abnormalities in endothelial function occur early in life, although symptoms usually do not appear until middle age.1 Cataract surgery in patients with Fuchs’ dystrophy presents a challenge because intraocular maneuvers result in endothelial cell damage. Increased nuclear Accepted for publication June 29, 2007. From the Department of Ophthalmology, District Railway Hospital, Katowice, Poland. Neither author has a financial or proprietary interest in any material or method mentioned. Corresponding author: Dorota Tarnawska, MD, Powstan´co´w 24/3, 40-039 Katowice, Poland. E-mail: [email protected]. Q 2007 ASCRS and ESCRS Published by Elsevier Inc.

density is associated with greater perioperative endothelial cell loss.2 There is a confirmed association between Fuchs’ dystrophy and nuclear cataracts3; patients with Fuchs’ dystrophy, therefore, have an additional risk factor for endothelial injury resulting from increased nuclear hardness. Cataract surgery decreases the number of corneal endothelial cells by 8% to 13%.4,5 In patients with Fuchs’ dystrophy, surgery can reduce the number of endothelial cells to such an extent that the extracellular matrix, basement membrane, and metabolic pump are compromised. This could lead to corneal decompensation, painful bullous keratopathy and, ultimately, the need for keratoplasty. Ophthalmic viscosurgical devices (OVDs), commonly used in modern cataract surgery, help create space, balance ocular pressure in the anterior and posterior chambers, stabilize the tissue, and protect corneal endothelial cells. Several OVDs are currently marketed, and they differ in rheologically active polymeric substances, concentrations, and chain lengths. These factors determine the viscosity, elasticity, and 0886-3350/07/$dsee front matter doi:10.1016/j.jcrs.2007.06.049

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cohesion of the OVD and affect other physical and chemical properties.6 The number of endothelial cells sufficient to maintain corneal transparency is unknown and probably varies among individuals. Current techniques in cataract surgery destroy approximately 10% of the corneal endothelial cells in patients with healthy corneas. One method, the soft-shell technique, uses different types of OVD substancesdcohesive and dispersivedto protect the corneal endothelium during phacoemulsification.7 The soft-shell technique might therefore be useful in cataract patients with a hard lens nucleus such as those with Fuchs’ dystrophy.8 In this study, we evaluated the protective ability of a modified soft-shell technique in patients with Fuchs’ dystrophy having phacoemulsification with intraocular lens (IOL) implantation. To our knowledge, this study is the first to compare OVDs in eyes with dystrophic corneas. PATIENTS AND METHODS This prospective study was designed as a consecutive interventional case series. Sixty-one eyes of 54 patients with clinically confirmed Fuchs’ dystrophy and with nuclear or corticonuclear senile cataracts graded from 2C to 4C on the Lens Opacities Classification System III9 (LOCS III) were selected for the study. Inclusion criteria were Fuchs’ dystrophy with cornea guttata in stages 3 to 4 according to Laing et al.,10 nuclear or corticonuclear cataract, no history of eye surgery or glaucoma in the study eye, a transparent central cornea, pupil dilation 7.0 mm or greater at the preoperative examination, anterior chamber depth greater than 2.2 mm, and absence of biomicroscopic signs of pseudoexfoliation. Patients with coexisting non-Fuchs’ corneal abnormalities were excluded. Patients with clinical evidence of corneal decompensation or preoperative corneal pachymetry measurements of more than 600 mm were also excluded and referred for a triple procedure (combined posterior lamellar keratoplasty or penetrating keratoplasty with cataract extraction and IOL implantation). All patients excluded from the study and referred for triple procedures also had damaged endothelium. Patients were informed by their first-contact ophthalmologist of their risk for corneal decompensation in the postsurgical course, including the need for corneal transplantation. Treatment was performed in accordance with the tenets of the Declaration of Helsinki. Institutional review board approval was obtained. Subjects provided written informed consent before surgery. The patients were randomized into 2 groups before cataract surgery based on the type of OVD used: sodium hyaluronate 1% (Healon) or chondroitin sulfate 4%–sodium hyaluronate 3% (Viscoat) in combination with sodium hyaluronate 1% (Provisc) in 1 package (DuoVisc).

Preoperative Evaluation Preoperative examination included assessment of nucleus hardness by slitlamp biomicroscopy, central pachymetry, intraocular pressure (IOP) measurement, endothelial cell count, and ocular comorbidity.

Central corneal thickness (CCT) was measured using a Pocket Precision ultrasonic pachymeter (Quantel Medical, Inc.). To reduce variability, 3 measurements in each eye were averaged and the preoperative and postoperative assessments were performed by the same experienced physician. The observer was blind to the treatment group. Measurements were taken throughout the day between 8 AM and 3 PM. Fuchs’ dystrophy was confirmed by noncontact specular microscopy (Topcon SP-2000, Topcon). In all patients, cornea guttata, polymegathism, and pleomorphism were confirmed and a decrease in cell density was visible; however, not all patients showed symptoms of early morning decompensation. The reliability of endothelial cell density measurements in stages 3 to 4 are limited by 2 factors: (1) interfering zones of separate or confluent central excrescences obscure the view of endothelial cells lying behind them, and (2) areas with guttae are distributed unevenly and the adjacent zones vary in cell number; hence, the endothelial cell number depends on the site that was photographed. An endothelial cell outline could not be observed in places so cell density could be accurately estimated in only 13 patients. Therefore, a decision was made not to base the statistical analysis in this series on endothelial cell density. It was assumed that in the presence of large cornea guttae, polymegathism, pleomorphism, and decreased cell density, increased corneal thickness is the manifestation of corneal edema caused by the deterioration of endothelial cell function.

Surgical Technique All procedures were performed by the same surgeon (D.T.) using topical anesthesia according to a standardized technique. The anterior chamber was filled with Healon or Viscoat followed by Provisc through a 3.2 mm clear corneal incision, and a curvilinear continuous capsulorhexis was created with a forceps. Hydrodissection and hydrodelineation were performed with balanced salt solution (BSS). Phacoemulsification was performed using the Quinto system (Oertli Instrumente AG) with a vacuum setting of 150 mm Hg, flow rate of 25 mL/min, and bottle height of 70 cm and less than 70% phaco power at an ultrasound frequency of 28 kHz. After in-the-bag phaco-chop phacoemulsification was performed, the cortical material was aspirated. For capsular bag expansion, only a cohesive OVD (Healon or Provisc) was used. After foldable IOL implantation, the OVD was evacuated from behind and in front of the IOL. After surgery, all patients received a combination of tobramycin 0.3% with dexamethasone 0.1% sulfate eyedrops 5 times daily for 1 week and then 3 times daily for 3 weeks. This was supplemented by sodium chloride 5% eyedrops 4 times daily for 1 month and tropicamide 1% 3 times daily for 1 week and then once daily for 2 weeks.

Postoperative Evaluation The postoperative examination included slitlamp biomicroscopy, central pachymetry, and IOP measurement. Central corneal thickness was determined by ultrasonic pachymetry. Examinations were performed 1 day, 1 week, and 1 and 6 months postoperatively. As in the preoperative evaluation, 3 central pachymetry measurements were averaged. When increased corneal thickness resulted in poor visual acuity, corneal decompensation was recognized and the patient was referred for posterior lamellar keratoplasty.

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Statistical Analysis

700

Alterations in corneal thickness between groups before and after surgery were tested using a Student t test for dependent values. Statistical differences between the Healon and DuoVisc groups were determined using a Student t test for independent groups. The correlation between corneal thickness before and after surgery was calculated using the Pearson coefficient. A P value less than 0.05 was considered statistically significant for all study outcome measures.

690

Pachymetry day 1

680

RESULTS

670 660 650 640 630 620 610

Preoperative Data

600

The study comprised 37 women and 17 men. Table 1 shows the patients’ characteristics in the 2 OVD groups. The proportions in each group with a lens opacity of NO2–NO4 (LOCS III) were similar. The morphologic changes in cornea guttata in Fuchs’ endothelial dystrophy observed with a specular photomicroscope matched stage 3 to stage 4. The mean preoperative CCT was 549.5 mm G 29.3 (SD) (range 481 to 599 mm), and the median was 552 mm. The mean preoperative IOP was 14.0 G 4.9 mm Hg in the DuoVisc group and 13.7 G 5.6 mm Hg in the Healon group. Postoperative Data The mean phacoemulsification time was 54.9 G 38.4 seconds in the DuoVisc group and 50.2 G 26.8 seconds in the Healon group. The difference between groups was not significant (P Z .302). On the first postoperative day, the mean IOP was significantly higher in the DuoVisc group (15.9 G 5.5 mm Hg) than in the Healon group (12.7 G 4.9 mm Hg; P Z .002). There was no statistically significant difference in IOP, however,

Table 1. Patients’ characteristics.

590

DuoVisc

Healon

Mean Mean±SE Mean±1,96*SE

Figure 1. Differences in postoperative CCT between groups at 1 day (P Z .003).

compared with the preoperative measurement (DuoVisc, P Z .16; Healon, P Z .75). At 1 week and subsequent postoperative measurements, there were no statistically significant differences between the groups and no statistically significant differences in IOP compared with the preoperative measurement. There was no correlation between postoperative IOP and CCT throughout the follow-up. The postoperative CCT was significantly greater in the Healon group at 1 day (P Z .003; Figure 1), 1 week (P Z .02), and 6 months (P Z .009; Figure 2). One month after surgery, there was a tendency toward a greater CCT value in the Healon group, although the difference was not statistically significant (Table 2). In both OVD groups, the postoperative CCT remained significantly greater than the preoperative CCT at every examination (P!.0001). The maximum CCT increase was on the first postoperative day (Tables 3 and 4). There was a statistically significant correlation between preoperative and postoperative CCTs. Figure 3

Group

Number of eyes Mean age (y) G SD Sex (n) Male Female Mean cataract grade (LOCS III)9 G SD Stage of endothelial dystrophy10 (n) Stage 3 Stage 4

DuoVisc

Healon

P Value

32 72.6 G 10.3

29 74.4 G 11.6

d .524* .963†

9 23 3.1 G 0.93

8 21 2.95 G 0.99

620 610

.745*

600

CCT month 6

Parameter

590 580 570

†

.932 18 14

16 13

LOCS III Z The Lens Opacities Classification System III *Unpaired t test † Chi-square test

560 550 540

DuoVisc

Healon

Mean Mean±SE Mean±1,96*SE

Figure 2. Differences in postoperative CCT between groups at 6 months (P Z . 009).

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DISCUSSION Fuchs’ dystrophy is one of the leading indications for corneal transplantation.11–13 The time required for visual rehabilitation after the triple procedure (penetrating keratoplasty, cataract extraction, and IOL implantation) is much longer than after cataract surgery, and visual outcomes are worse. A newer surgical technique, posterior lamellar keratoplasty, provides faster recovery after the triple procedure and better outcomes due to minimal postoperative astigmatism.

However, even after this type of surgery, the patient requires many months for visual rehabilitation. Several patient-related and surgery-related risk factors for perioperative endothelial cell loss should be taken into consideration preoperatively and intraoperatively. In our selected group, there were strong risk factors, such as morphologic and functional abnormalities of the endothelium. More effective protection of the endothelium could increase the percentage of Fuchs’ dystrophy patients who achieve visual rehabilitation after cataract surgery alone without concurrent keratoplasty. Poyer et al.14 speculate that the protective effect of Viscoat results from its coating properties, whereas Healon more effectively maintains the anterior chamber, allowing safe surgical maneuvers. Some studies confirmed that the dispersive qualities of Viscoat protect the endothelium better than cohesive OVDs,15,16 whereas others report that cohesive and dispersive OVDs are equally effective.17–21 These authors compared OVDs used alone. Arshinoff7 popularized the use of a combination of sequentially applied cohesive and dispersive OVDs in a phacoemulsification technique called the soft-shell technique because it improved surgical results compared with using either OVD alone. A newer modification, the ultimate softshell technique,22 uses OVDs and BSS. Miyata et al.8 and Kim and Joo23 found the soft-shell technique beneficial in patients with hard lens nuclei having cataract surgery. Behndig and Lundberg24 report that in the first week after surgery, the mean increase in corneal thickness was significantly smaller in groups operated on using a variation of the soft-shell technique (Viscoat combined with Healon GV or Viscoat with Provisc) than in a group in which Healon GV alone was used. The major drawback of Viscoat is its tendency to increase IOP in the early postoperative hours in the case of incomplete removal, which occurs because of the

Table 3. Comparison of preoperative and postoperative CCT in the Healon group.

Table 4. Comparison of preoperative and postoperative CCT in the Duovisc group.

Table 2. Distribution of mean CCT in DuoVisc and Healon groups. Number of Eyes Exam Preop Postop 1d 1 wk 1 mo 6 mo

DuoVisc Healon

Mean CCT (mm) G SD DuoVisc

Healon

P Value

32

29

547 G 29

552 G 29

.4

32 32 32 32

29 29 29 29

618 G 54 609 G 52 586 G 52 557G 31

665 G 64 644 G 65 610 G 56 588 G 57

.003 .022 .08 .008

CCT Z central corneal thickness.

shows the scatterplots and regression lines in the Duo Visc and Healon groups 6 months postoperatively. The correlation after 6 months was selected for graphic presentation because of the clinical relevance of a longer follow-up. The regression line in the Healon group is above the line in the DuoVisc group, which might indicate that corneas in the Healon group were thicker postoperatively. Six months after surgery, the mean postoperative CCT was lower in the DuoVisc group (P Z .003).

Exam Preop Postop 1d 1 wk 1 mo 6 mo

Relative Mean CCT Number CCT (mm) Increase of Eyes G SD Difference (%)

P Value*

Exam

.000000 .000000 .000001 .00022

Preop Postop 1d 1 wk 1 mo 6 mo

552 G 29 29 29 29 29

665 G 64 644 G 65 610 G 56 588 G 57

113 92 58 36

20.3 16.5 10.5 6.5

CCT Z central corneal thickness. *Student t test for dependent groups; P!.05 statistically significant

Relative Mean CCT Number CCT (mm) Increase of Eyes G SD Difference (%)

P Value*

547 G 29 32 32 32 32

618 G 64 609 G 65 586 G 56 557 G 57

71 62 39 10

13.2 11.3 7.1 1.8

.000000 .000000 .000003 .000003

CCT Z central corneal thickness. *Student t test for dependent groups; P!.05 statistically significant

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850

CCT 6 month post-op

800 750 700 650 600 550 500 450 460

480

500

520

540

560

Preoperative CCT

580

600

620

Healon DuoVisc

Figure 3. The correlation between CCT in the DuoVisc group and Healon group preoperatively and 6 months postoperatively.

OVD’s coating ability.14,19,25,26 To solve this problem, special aspiration techniques are recommended; these include the rock ‘n’ roll technique of Arshinoff27 and the 2-compartment technique of Tetz and Holzer.28 In contrast, some authors argue that the prolonged irrigation and aspiration maneuvers involved in removing Viscoat might cause greater endothelial damage than if the OVD were left in the anterior chamber.20 For patients with Fuchs’ endothelial dystrophy, Arshinoff recommends leaving the dispersive agent in the eye; at the end of surgery, an ocular hypotensive agent is administered to prevent a postoperative IOP increase (M. Lipner, ‘‘Five Strategies to Best Use the Ultimate Soft Shell Technique,’’ EyeWorld, January 2004, page 25). We departed from the original soft-shell technique, in which the capsular bag is filled first with a cohesive OVD and then centrally filled with a dispersive OVD, to facilitate positioning the IOL in the bag. In our series, only a cohesive OVD (Healon or Provisc) was used during capsular bag expansion to eliminate the potential influence of prolonged aspiration of Viscoat on the CCT and to reduce the probability of a postoperative spike in IOP that could induce an increase in the CCT. Corneal thickness before cataract extraction in patients with Fuchs’ dystrophy is a good predictor of endothelial cell function and a prognostic factor for the future development of corneal edema.29–31 A postoperative increase in CCT is strongly correlated with preoperative pachymetry. The CCT increase was significantly greater in the Healon group 1 day, 1 week, and 6 months postoperatively. Despite a standard treatment regimen to reduce swelling (sodium chloride 5%), the CCT in both groups remained significantly greater than before surgery for up to 6 months.

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Other studies8,23 found that in patients with healthy corneas, CCT values returned to preoperative levels within 1 week after cataract surgery using the soft-shell technique. Our study found that in patients with Fuchs’ dystrophy, the CCT remained greater after treatment, although it gradually decreased over time. Although CCT did not fully recover even 6 months postoperatively regardless of the OVD used, the results were satisfactory. Only 1 patient (Healon group, preoperative pachymetry 563 mm, lens opacity NO4, stage 3 cornea guttata) had corneal decompensation greater than 800 mm; this occurred on postoperative day 1 and did not resolve during follow-up. This resulted in poor visual acuity, and the patient required keratoplasty. All patients were informed of the progressive nature of their disease and the increased risk for corneal decompensation. Also, patients with preoperative pachymetry near the upper limit were informed of an expected visual acuity decrease due to the thick cornea (even in the absence of decompensation or epithelial edema). A percentage of the operated eyes might eventually require keratoplasty. Early cataract extraction before advanced lens maturation can eliminate the need for more complicated surgery later. Some patients in this study had a relatively hard nucleus because they delayed their surgery decision because of previous complications after cataract surgery in the fellow eye. These patients were particularly satisfied with the uneventful postoperative period because they were aware of the possible complications, including corneal transplantation. In conclusion, the soft-shell technique effectively protected the compromised endothelium in patients with Fuchs’ dystrophy. The advantages are clear in eyes with a moderately damaged endothelium with minimal or no corneal edema. For a more compromised endothelium, the protection might not be as effective in keeping the number of endothelial cells above the threshold number for corneal transparency. Further study is needed to determine whether the recommendation for cataract surgery alone in eyes with more swollen corneas should be expanded. REFERENCES 1. Wilson SE, Bourne WM. Fuchs’ dystrophy. Cornea 1988; 7:2–18 2. Hayashi K, Hayashi H, Nakao F, Hayashi F. Risk factors for corneal endothelial injury during phacoemulsification. J Cataract Refract Surg 1996; 22:1079–1084 3. Naumann GOH, Schlo¨tzer-Schrehardt U. Keratopathy in pseudoexfoliation syndrome as a cause of corneal endothelial decompensation; a clinicopathologic study. Ophthalmology 2000; 107:1111–1124 4. Walkow T, Anders N, Klebe S. Endothelial cell loss after phacoemulsification: relation to preoperative and intraoperative parameters. J Cataract Refract Surg 2000; 26:727–732

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