Purpose
To investigate the prevalence and morphologic changes of capsular bag distention syndrome after cataract surgery using the Pentacam and to analyze its clinical characteristics and influencing factors.
Design
Retrospective, cross-sectional study.
Methods
Clinical records of 239 consecutive patients who underwent cataract surgery were reviewed. Demographic data, use of intraoperative ophthalmic viscosurgical devices, type of intraocular lens implanted, axial length, and white-to-white corneal diameter were recorded. One month after surgery, dilated Scheimpflug imaging was performed. Prevalence, morphologic changes, and characteristic clinical findings of this syndrome were evaluated.
Results
Using Scheimpflug imaging, the prevalence of capsular bag distention syndrome was high at 26.8% (64/239), and it was possible to classify its morphologic changes into 3 types. Patients with the syndrome had poorer best-corrected visual acuity and lower satisfaction scores than those without the syndrome ( P = .041 and P = .008, respectively). Although there was no significant difference observed in rate of this syndrome between the 2 ophthalmic viscosurgical devices used in our study ( P > .05), implantation of 4-haptic intraocular lenses was associated with a high prevalence of the syndrome (odds ratio, 2.07; 95% confidence interval, 1.05 to 4.07; P = .0346). Patients with this syndrome had significantly longer AL (26.26 ± 2.84 mm) and white-to-white diameter (12.02 ± 0.34 mm) than those without (AL, 24.63 ± 2.89 mm; white-to-white diameter, 11.81 ± 0.32 mm; P = .0002 and P < .0001, respectively).
Conclusions
Scheimpflug imaging revealed the prevalence of capsular bag distention syndrome to be high, and these patients generally had poorer visual outcomes. Intraocular lens design and dimensions of the eyes significantly influenced the prevalence of this syndrome.
Capsular bag distension syndrome is considered a rare complication occurring after cataract surgery when diagnosis is based on slit-lamp biomicroscopy. Recently, Scheimpflug imaging (Pentacam HR; Oculus Optikgerate GmbH, Wetzlar, Germany) demonstrated advantages in detecting morphologic changes in the anterior segment caused by capsular bag distension syndrome. It allows precise documentation of the phenomenon, including exact measurements of the distended posterior capsule, turbidity of the fluid, and intraocular lens (IOL) position. However, because this complication occurs with low incidence, systematic studies of the morphologic changes caused by the syndrome, using the Pentacam system or other anterior segment imaging techniques, are rare. In the present study, using Scheimpflug imaging, we found that the prevalence of capsular bag distension syndrome actually is high after cataract surgery, and we carefully studied its morphologic characteristics.
Miyake and associates and Nishi and associates classified capsular bag distension syndrome into 3 types according to the time of onset: intraoperative, early postoperative, and late postoperative. In early postoperative capsular bag distension syndrome, occurring between 1 day and 2 weeks after surgery, transparent liquid accumulates between the IOL and the distended posterior capsule. Sugiura and associates identified this liquid as diluted sodium hyaluronate, the main ingredient of retained ophthalmic viscosurgical devices (OVDs). Another study reported a patient in whom capsular bag distension syndrome developed on the fifth day after surgery and was found to have cortical material trapped behind the IOL. Saccadic eye movements also may contribute to the development of capsular bag distension syndrome. However, most of these studies enrolled insufficient numbers of patients with capsular bag distension syndrome to draw credible conclusions regarding its cause.
In the present study, we identified 64 cases of capsular bag distension syndrome with Scheimpflug imaging and evaluated their visual outcomes. We further explored its cause by reviewing the clinical records of these patients, as well as those cases that were not capsular bag distension syndrome. Possible influencing factors were investigated, including age, gender, OVD use, IOL type, axial length (AL), and white-to-white diameter of the eyes.
Methods
The Institutional Review Board of the Eye and ENT Hospital of Fudan University, Xuhui, Shanghai, China, approved this retrospective, cross-sectional study. All procedures adhered to the tenets of the Declaration of Helsinki and were conducted in accordance with the approved research protocol. Informed consent for research use of patients’ clinical records was obtained from each participant before participation. The study was registered at www.clinicaltrials.gov ; the clinical trial accession number is NCT01868217 .
Subjects
We performed retrospective chart review of 239 consecutive patients who underwent uneventful phacoemulsification and posterior-chamber IOL implantation at the Eye and ENT Hospital of Fudan University between November 2011 and December 2012. Eyes with fundus pathologic features, previous trauma, glaucoma, or zonular weakness were excluded from the study, as were eyes with intraoperative or postoperative complications, such as a posterior capsule opening, radial tearing of the continuous curvilinear capsulorrhexis, a reversed-optic IOL, or pupillary capture of IOL.
Preoperative Examination
Before surgery, routine ophthalmic examinations were conducted, including assessment of visual acuity, funduscopy, tonometry, corneal topography (Pentacam HR; Oculus Optikgerate GmbH, Wetzlar, Germany), B-scan ultrasonography, and measurement of AL and white-to-white diameter using IOLMaster devices (Carl Zeiss AG, Oberkochen, Germany).
Surgical Technique
After topical anesthesia with oxybuprocaine hydrochloride eye drops (Santen Pharmaceutical Co., Osaka, Japan), a 2.6-mm clear corneal incision was created, followed by a continuous curvilinear capsulorrhexis that was 0.5 mm smaller than the optic. Hydrodissection, chopping, nucleus rotation, and phacoemulsification then were performed. Irrigation and aspiration of the cortex was followed by insertion of the IOL into the capsular bag. After removal of the viscoelastics, the incisions were hydrated with balanced salt solution. Stitches were not used in any patient. After surgery, TobraDex (tobramycin/dexamethasone eye ointment; Alcon NV/SA, Vilvoorde, Belgium) was instilled into the treated eye. From the first day after surgery, patients were instructed to apply Cravit eye drops (levofloxacin; Santen Pharmaceutical Co. Ltd.) and prednisolone acetate (Allergen Pharmaceutical Ireland, Westport, County Mayo, Ireland) 4 times daily for 2 weeks and pranopulin (Pranoprofen; Senju Pharmaceutical Co. Ltd., Osaka, Japan) 4 times daily for 1 month.
Postoperative Evaluation
Routine ophthalmic examinations, including assessment of visual acuity, refraction, funduscopy, and tonometry, were conducted at 1 month after surgery. Uncorrected visual acuity (measured in logarithm of the minimal angle of resolution [logMAR] units), best-corrected visual acuity (measured in logMAR units), and spherical equivalent were recorded. The overall results for patient satisfaction with the surgery were recorded on a 10-point scale ranging from 1 = very bad to 10 = excellent. Patients’ pupils were dilated using a mixture of 0.5% phenylephrine and 0.5% tropicamide (Mydrin P; Santen Pharmaceutical Co.). Anterior segment photography was performed. Pentacam examinations were undertaken, and the data collected by the Scheimpflug device were used only if the data-quality statement reading was “OK”. For each subject, the Scheimpflug Image Overview function was used to examine the 25 images obtained during 1 measurement to evaluate the overall morphologic characteristics of the posterior capsule. The postoperative anterior chamber depth, defined as the distance between the posterior corneal surface and the anterior IOL surface, was measured manually after adjusting the contrast of the Scheimpflug image. Clinical data from 36 patients, including 8 capsular bag distension cases, also were collected ( Supplemental Table , available at AJO.com ). Wavefront aberrometry (KR-1W; Topcon, Tokyo, Japan) examinations were carried out. Wavefront aberration data included total higher order aberrations, trefoil, coma, spherical, third-order, and 4th-order aberrations of Zernike polynomials, calculated as root mean square values. The aberrometer also provided modulation transfer function curves (for both the x-axis and y-axis) and the Strehl ratio value obtained from point spread function as optical quality indices of eyes.
Capsular bag distension syndrome was defined as the presence of capsular bag distension and attachment of the anterior capsule margin to the IOL optic on Scheimpflug imaging. Morphologic classification of capsular bag distension syndrome was performed according to Scheimpflug imaging. Patients with intraoperative capsular block syndrome were excluded from this study.
Statistical Analysis
Demographic variables recorded included age, gender, and eye(s) operated on. Other variables included OVD type, type of IOL inserted, AL, and white-to-white diameter. All data were expressed as the mean ± standard deviation. Logistic regression analysis was used to analyze the association between IOL type and prevalence of capsular bag distension syndrome. One-way analysis of variance was used to compare quantitative data. Subsequent mean comparisons were carried out using the least significant difference test. P values less than .05 were considered statistically significant. All analyses were performed using SPSS software version 11.0 (SPSS, Inc, Chicago, Illinois, USA).
Results
Prevalence and Morphologic Classification of Capsular Bag Distension Syndrome With Pentacam
The overall 1-month prevalence of capsular bag distension syndrome was 26.8% (64/239) when observed by Pentacam. Examination by Scheimpflug imaging revealed 3 types of morphologic change of the distended posterior capsule ( Figure ):
- 1.
Type I, sector: a fan-shaped space exists between the IOL optic and the posterior capsule. Prevalence: 6.3% (15/239).
- 2.
Type II, concentric ring: space exists only between the center of the IOL optic and the posterior capsule. Prevalence: 8.4% (20/239).
- 3.
Type III, full area: space exists between the entire IOL optic and the posterior capsule. Prevalence: 12.1% (29/239).
The liquid accumulated in the space was transparent in all 3 types.
The morphologic characteristics of each type as identified by Scheimpflug imaging are illustrated in Table 1 . Posterior displacement of the posterior capsule was evaluated by measuring the maximum vertical distance between the optic and posterior capsule; the angle of the sector also was measured in patients with type I capsular bag distension syndrome. The mean maximum vertical distance in patients with type III capsular bag distension syndrome was significantly larger than that in patients with types I and II capsular bag distension syndrome ( P = .004 and P < .0001, respectively). A relatively small maximum vertical distance increases the difficulty of diagnosing capsular bag distension syndrome using slit-lamp biomicroscopy.
| Type | Morphologic Characteristics | |
|---|---|---|
| Maximal Vertical Distance (mm) | Angle (Degrees) | |
| I: Sector | 0.31 ± 0.11 a | 123.0 ± 83.0 |
| II: Concentric ring | 0.24 ± 0.07 a | — |
| III: Full area | 0.42 ± 0.14 | — |
| Total | — | — |
a Compared with type III, the maximal vertical distance of other 2 types of capsular bag distention syndrome were significantly smaller ( P = .004 and P < .0001, respectively).
Clinical Characteristics of Capsular Bag Distension Syndrome
Clinical characteristics of each group are shown in Table 2 . Average uncorrected visual acuity in patients with and without capsular bag distension syndrome was 0.44 ± 0.32 logMAR and 0.37 ± 0.24 logMAR, respectively, and no statistically significant difference was evident between these 2 groups ( P > .05). Average spherical equivalent in patients with and without this syndrome was −1.84 ± 0.70 diopters (D) and −1.13 ± 0.84 D, respectively ( P < .0001). Average best-corrected visual acuity was 0.19 ± 0.26 logMAR and 0.12 ± 0.20 logMAR, respectively, and this difference was statistically significant ( P = .041). Patients with this syndrome had lower satisfaction scores (7.6 ± 1.2) than those without (8.1 ± 1.5; P = .008). Capsular bag distension syndrome patients had a deeper anterior chamber (4.03 ± 0.43 mm) than those without (3.78 ± 0.46 mm; P < .0001). No statistically significant differences were found for all these parameters among the 3 types of capsular bag distension syndrome (all P > .05). Patients with capsular bag distension syndrome also tend to have worse visual quality, as indicated by the total higher order aberrations, modulation transfer function curves, and Strehl ratio values ( Supplemental Figure , available at AJO.com ).
| Parameter | Patients with Capsular Bag Distention Syndrome | Patients without Capsular Bag Distention Syndrome | ||
|---|---|---|---|---|
| Type I | Type II | Type III | ||
| UCVA (logMAR) | 0.44 ± 0.28 | 0.43 ± 0.33 | 0.44 ± 0.34 | 0.37 ± 0.27 |
| SE (D) | −1.71 ± 0.54 | −1.79 ± 0.66 | −1.93 ± 0.79 | −1.13 ± 0.84 |
| BCVA (logMAR) | 0.17 ± 0.26 | 0.17 ± 0.27 | 0.20 ± 0.27 | 0.12 ± 0.20 |
| Patient satisfaction (10-point scale) | 7.6 ± 1.0 | 7.7 ± 1.3 | 7.4 ± 1.3 | 8.1 ± 1.5 |
| ACD (mm) | 3.89 ± 0.45 | 4.00 ± 0.46 | 4.12 ± 0.38 | 3.78 ± 0.46 |
Influencing Factors of Capsular Bag Distension Syndrome
Demographic data
The demographic data of each group are shown in Table 3 . Age, gender, and operated eye were unrelated to the prevalence of postoperative capsular bag distension syndrome (all P > .05). Two types of intraoperative OVDs were used in this study: Amvisc (Bausch & Lomb [Shanghai] Trading Co., Ltd., Shanghai, China), used in 81.2% (194/239) of patients, and Duovisc (Alcon Laboratories, Inc, Fort Worth, Texas, USA), used in 18.8% (45/239) of patients. The prevalence of capsular bag distension syndrome for each of these 2 OVDs was 27.3% (53/194) and 24.4% (11/45), respectively, and no statistically significant difference was evident between these 2 viscoelastics ( P > .05).
| Parameter | Patients with Capsular Bag Distention Syndrome | Patients without Capsular Bag Distention Syndrome | ||
|---|---|---|---|---|
| Type I | Type II | Type III | ||
| Mean age ± SD (y) | 66.9 ± 10.4 | 63.4 ± 14.7 | 64.4 ± 10.5 | 66.2 ± 13.5 |
| Sex (male/female) | 7/8 | 10/10 | 17/12 | 69/106 |
| No. of operated eyes (right/left) | 9/6 | 8/12 | 13/16 | 92/83 |
| OVD (Amvisc/Duovisc) | 10/5 | 17/3 | 23/6 | 144/31 |
Intraocular lens type
The types of IOL used in the present study are shown in Table 4 . Among the 6 IOLs used most frequently in the present study, the Akreos ADAPT AO (Bausch & Lomb [Shanghai] Trading Co., Ltd.) and MC X11 ASP (HumanOptics AG, Erlangen, Germany) are 4-haptic IOLs. Postoperative capsular bag distension syndrome was more prevalent with 4-haptic than with 2-haptic IOL use (odds ratio, 2.07; 95% confidence interval, 1.05 to 4.07; P = .0346). With 4-haptic IOL use, type II capsular bag distension syndrome was the most common morphologic change (45%, 13/29). However, with 2-haptic IOL use, type III capsular bag distension syndrome constituted most capsular distention changes (54%, 19/35).
