Purpose
To compare the outcome of primary anterior chamber vs secondary scleral-fixated intraocular lens (IOL) implantation in complicated cataract surgeries.
Design
Retrospective, comparative study.
Methods
A consecutive series of complicated cataract surgeries with primary anterior chamber (ACIOL) or secondary scleral-fixated IOL implantation from January 1, 2004 to December 31, 2009 was analyzed. Main outcome measures included the postoperative best-corrected visual acuity (BCVA) and postoperative complications.
Results
There were 89 eyes in the primary ACIOL group and 74 eyes in the secondary scleral-fixated IOL group. The mean follow-up duration was 64.1 ± 36.7 months. The mean postoperative logarithm of minimal angle of resolution (logMAR) BCVA at 1 year was 0.32 ± 0.54 and 0.34 ± 0.21 in the primary ACIOL group and the secondary scleral-fixated IOL group, respectively ( P = .734). The mean latest logMAR BCVA was 0.68 ± 0.54 and 0.61 ± 0.47 in the primary ACIOL group and the secondary scleral-fixated IOL group, respectively ( P = .336). The primary ACIOL group had more early postoperative complications ( P < .001). No difference in late postoperative complications was observed between the 2 groups ( P = .100). Regression analysis showed that primary ACIOL and secondary scleral-fixated IOL implantation had similar latest postoperative logMAR BCVA ( P = .927), while the presence of late complications was associated with a worse final visual outcome ( P = .000).
Conclusions
This study shows that there are no long-term differences in the visual outcomes and complication profiles after primary ACIOL or secondary scleral-fixated IOL implantation in a complicated cataract operation when capsular support is inadequate.
Cataract extraction is the most commonly performed ophthalmic surgery. Implantation of posterior chamber intraocular lens (IOL) is always desirable in the presence of sufficient capsular support. In complicated cataract surgery when capsular support is inadequate for IOL implantation in the capsular bag or at the ciliary sulcus, the surgeon needs to decide whether to implant an anterior chamber IOL (ACIOL) or a scleral-fixated IOL. With the development of the open-loop haptic design, ACIOL regained its popularity because of the ease of insertion and better safety profile. Primary ACIOL implantation has been compared to primary scleral-fixated IOL implantation in a study from our hospital showing better visual outcomes and noninferior complication profiles. On the contrary, secondary ACIOL and scleral-fixated IOL implantation were reported to have similar visual outcomes and late complications.
In our setting, surgeons often choose between primary ACIOL or secondary scleral-fixated IOL implantation when cataract surgery is complicated owing to the loss of posterior capsule. Primary scleral-fixated IOL is not a common choice, since not all surgeons are familiar with the surgical technique. Moreover, the surgical slot is often tightly packed, making prolonged operation logistically difficult. The main advantage of primary ACIOL insertion is the avoidance of a second operation. However, there are potential risks of corneal edema and intraocular pressure escalation. On the other hand, secondary scleral-fixated IOL implantation allows for better surgical planning, yet an additional operation is needed.
The present study aims to compare the outcomes of primary ACIOL vs secondary scleral-fixated IOL implantation in complicated cataract surgeries.
Methods
This is a retrospective study of all the consecutive primary ACIOL and secondary scleral-fixated IOL implantation surgeries performed at Hong Kong Eye Hospital from January 1, 2004 to December 31, 2009. Patients were identified by a search from the logbook documenting cataract and IOL surgeries during the study period. The study was conducted in accordance with the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board of the Kowloon Central Cluster, Hospital Authority, Hong Kong. Exclusion criteria included: (1) causes of poor visual function other than cataract, such as amblyopia, macular scar, and optic atrophy before cataract surgery; (2) pathologic features that would dictate the choice of IOL implantation, such as uveitis and glaucoma; (3) combined surgery, including corneal surgery, glaucoma surgery, and pars plana vitrectomy; and (4) postoperative follow-up of less than 12 months. Patient demographics, follow-up duration, type of cataract operation planned, type of IOL implanted, postoperative best-corrected visual acuity (BCVA) and refraction at 1 year after surgery, latest BCVA, and postoperative complications were collected from each case record.
Surgical technique for IOL implantation in both groups was the same as previously described. In the primary ACIOL group, Pharmacia 351C lenses (Pharmacia International, Capelle aan den Ijssel, The Netherlands) or Bausch & Lomb S112UV lenses (Bausch & Lomb Inc, New York, New York, USA) were implanted. Both lenses are single-piece polymethyl methacrylate (PMMA), open-loop, semi-flexible lens with 4-point fixation. In the secondary scleral-fixated IOL group, Alcon CZ70BD lenses (Alcon Laboratories, Forth Worth, Texas, USA), a single-piece PMMA lens with eyelets, were used for all secondary scleral-fixated IOL implantations in the current study.
Statistical analyses were performed using PASW software version 18.0 (SPSS/IBM Inc, Chicago, Illinois, USA). Descriptive statistics in both treatment groups were reported. Snellen BCVA was converted into logarithm of the minimal angle of resolution (logMAR) units for analysis. Visual acuities of hand movement and light perception were arbitrarily assigned the equivalent of 1.7 and 1.8 logMAR units, respectively. Group means were compared with independent t test. Complication rates were evaluated using χ 2 test or Fisher exact test. A multiple linear regression model with latest BCVA as the dependent variable was constructed. Collinearity diagnostic, using an averaged variance inflation factor of more than 3 as cutoff, was included. A P value of <.05 was considered as statistically significant.
Results
A total of 163 eyes of 153 patients were included in the current study. There were 89 eyes in the primary ACIOL group and 74 eyes in the secondary scleral-fixated IOL group. The mean age was 76.2 ± 9.6 years. The mean age of patients in the primary ACIOL group was significantly older than that of the secondary scleral-fixated IOL group ( P < .001). The mean follow-up duration was 64.1 ± 36.7 months, with no significant difference between the 2 groups ( P = .915).
The mean postoperative BCVA was similar between the 2 groups at 1 year after IOL implantation ( P = .734). The mean postoperative logMAR BCVA at 1 year was 0.32 ± 0.54 and 0.34 ± 0.21 in the primary ACIOL group and the secondary scleral-fixated IOL group, respectively. The latest BCVA was also similar between the 2 groups ( P = .336). The latest logMAR BCVA was 0.68 ± 0.54 and 0.61 ± 0.47 in the primary ACIOL group and the secondary scleral-fixated IOL group, respectively. There was also no significant difference in the proportion of eyes having a Snellen BCVA of 20/40 or better between the 2 groups at 1 year after IOL implantation ( P = .647) or at the last follow-up ( P = .378). Absolute spherical equivalent was 1.38 ± 1.03 diopters in the primary ACIOL group and 1.63 ± 1.11 diopters in the secondary scleral-fixated IOL group, with no significant difference between groups ( P = .139). Also, there was no intergroup difference in astigmatism ( P = .672). Patient demographics and postoperative visual outcomes are summarized in Table 1 .
| Intraocular Lens Type | P Value | ||
|---|---|---|---|
| 1° Anterior Chamber IOL | 2° Scleral-Fixated IOL | ||
| Number of eyes | 89 | 74 | |
| Age of patients (y) at the time of operation | 78.8 ± 6.6 | 73.1 ± 11.5 | .000 |
| Sex, n (%) | .348 | ||
| Male | 30 (33.7%) | 30 (40.5%) | |
| Female | 59 (66.3%) | 44 (59.5%) | |
| Planned operation, n (%) | .000 | ||
| Phacoemulsification | 34 (59.6%) | 72 (82.8%) | |
| Extracapsular cataract extraction | 23 (40.4%) | 15 (17.2%) | |
| Follow-up duration (mo) a | 63.8 ± 39.6 | 64.5 ± 33.3 | .915 |
| Postoperative logMAR BCVA at 1 year a | 0.32 ± 0.54 | 0.34 ± 0.21 | .734 |
| Absolute astigmatism (diopters) at 1 year a | 2.25 ± 1.79 | 2.36 ± 1.50 | .672 |
| Absolute spherical equivalent (diopters) at 1 year a | 1.38 ± 1.03 | 1.63 ± 1.11 | .139 |
| Postoperative logMAR BCVA at last follow-up a | 0.68 ± 0.54 | 0.61 ± 0.47 | .336 |
Early (within 1 month) postoperative complications occurred in 62 of 89 eyes (69.7%) and 29 of 74 eyes (39.7%) in the primary ACIOL group and the secondary scleral-fixated IOL group, respectively ( P < .001). The primary ACIOL group had significantly more transient corneal edema ( P < .001) and residual lens material ( P = .003) compared to the secondary scleral-fixated IOL group. Late (after 1 month) postoperative complications occurred in 23 of 89 eyes (25.8%) and 28 of 74 eyes (37.8%) in the primary ACIOL group and the secondary scleral-fixated IOL group, respectively ( P = .100). There were no differences in each of the late postoperative complications between the 2 groups ( P < .115). Early and late postoperative complications are shown in Table 2 . Among the cases in which patients suffered from persistently elevated intraocular pressure, 1 eye (1/12; 8.3%) following primary ACIOL insertion needed laser cyclophotocoagulation ( P = 1.000), while 2 eyes (2/17; 11.8%) receiving secondary scleral-fixated IOL placement needed trabeculectomy ( P = .485). Suture erosion occurred in only 2 eyes (2/74; 2.7%) with scleral-fixated IOL implanted ( P = .118). There were no cases of IOL-pupil capture, IOL dislocation, or endophthalmitis associated with stitch erosion encountered in our patients following scleral-fixated IOL implantation.
| Intraocular Lens Type | P Value | ||
|---|---|---|---|
| 1° Anterior Chamber IOL | 2° Scleral-Fixated IOL | ||
| Number of eyes | 89 | 74 | |
| Early complications (within 1 mo) | |||
| Transient corneal edema | 49 (66.6%) | 16 (21.6%) | .000 |
| Vitreous hemorrhage | 6 (6.7%) | 9 (12.2%) | .222 |
| Intraocular pressure >30 mm Hg | 11 (12.4%) | 8 (10.8%) | .783 |
| Residual lens material | 13 (14.6%) | 1 (1.4%) | .003 |
| Severe uveitis | 4 (4.5%) | 5 (6.8%) | .515 |
| Fibrin | 1 (1.1%) | 0 (0.0%) | .364 |
| Hyphema | 7 (7.9%) | 3 (4.1%) | .323 |
| Vitreous incarceration at wound site | 0 (0.0%) | 1 (1.4%) | .268 |
| Intraocular lens capture | 1 (1.1%) | 0 (0.0%) | .364 |
| Choroidal detachment | 2 (2.2%) | 2 (2.7%) | .841 |
| Retinal detachment | 1 (1.1%) | 0 (0.0%) | .364 |
| Endophthalmitis | 2 (2.2%) | 0 (0.0%) | .194 |
| Number of eyes with early complications | 62 (69%) | 29 (39.2%) | .000 |
| Late complications (after 1 mo) | |||
| Bullous keratopathy | 11 (12.4%) | 8 (10.8%) | .783 |
| Persistent intraocular pressure >21 mm Hg | 12 (13.5%) | 17 (23.0%) | .115 |
| Vitreous prolapse into anterior chamber | 3 (3.4%) | 4 (5.4%) | .524 |
| Persistent uveitis | 1 (1.1%) | 4 (5.4%) | .118 |
| Intraocular lens decentration | 1 (1.1%) | 3 (4.1%) | .229 |
| Pseudophakic cystoid macular edema | 3 (3.4%) | 2 (2.7%) | .805 |
| Retinal detachment | 1 (1.1%) | 0 (0.0%) | .360 |
| Number of eyes with late complications | 23 (25.8%) | 28 (37.8%) | .100 |
Eyes without long-term complications had better latest BCVA than eyes with complications ( P < .001 for both groups). There was no difference in the latest postoperative BCVA ( P = .883) and latest Snellen BCVA of 20/40 or better ( P = .911) between the 2 groups in the eyes with no late complications. The latest postoperative logMAR BCVA in the eyes with no late complications was 0.48 ± 0.30 and 0.49 ± 0.33 in the primary ACIOL group and the secondary scleral-fixated IOL group, respectively. On the contrary, the primary ACIOL group had worse postoperative BCVA ( P = .031) and latest Snellen BCVA of 20/40 or better ( P = .023) compared to the secondary scleral-fixated IOL in the eyes with late complications. The latest postoperative logMAR BCVA in the eyes with late complications was 1.25 ± 0.63 and 0.86 ± 0.59 in the primary ACIOL group and the secondary scleral-fixated IOL group, respectively.
The types of cataract operation planned were known in 144 eyes, including 87 of 88 eyes (97.8%) and 57 of 74 eyes (77.0%) in the primary ACIOL group and the secondary scleral-fixated IOL group, respectively. There were more cataract operations unidentified in the secondary scleral-fixated IOL group because those cases were referred to our hospital for secondary IOL insertion from the private sector. A total of 72 eyes (72/87; 82.8%) in the primary ACIOL group and 34 eyes (34/57; 59.6%) in the secondary scleral-fixated IOL group underwent phacoemulsification ( P < .001). Extracapsular cataract extraction was planned in 15 eyes (15/87; 17.2%) and 23 eyes (23/57; 40.4%) in the primary ACIOL group and the secondary scleral-fixated IOL group, respectively ( P < .001). Indeed, most cases were converted to extracapsular cataract extraction when there was inadequate capsular support during phacoemulsification.
A multiple linear regression model was constructed with the latest logMAR BCVA as the dependent variable and IOL group (primary ACIOL group vs secondary scleral-fixated IOL group), age of patient, postoperative logMAR BCVA at 1 year, presence of early postoperative complication, presence of late postoperative complication, and type of cataract operation planned as the independent variables. There was no evidence of correlation or interaction among the variables included in the regression model. The presence of late complication was an independent predictor for poorer logMAR BCVA at the last follow-up ( P < .001). None of the other independent variables was significantly associated with the latest logMAR BCVA. The regression model summary for latest logMAR BCVA is shown in Table 3 . Similar results were seen when the type of cataract operation planned was excluded because the cataract was actually extracted differently than planned. The regression model summary with the type of cataract operation excluded among other independent variables is shown in Table 4 .
