Phacoemulsification has been referred to as a refractive surgery due to the development of surgical techniques and refraction-correcting IOLs. An accurate prediction of postoperative refraction is important in refractive cataract surgery. The anterior capsule contraction syndrome (ACCS) is a well-recognized postoperative complication. The outcomes of ACCS are opacification, fibrosis, and contraction of the anterior capsule [
High myopic patients, especially with axial length of >27.0 mm, probably have an enlarged capsular bag with weak zonules and tend to develop cataracts earlier than emmetropic patients [
The objective of this study is to determine if the anterior capsule polishing is beneficial to reduce the extent of the anterior capsule contraction and increase the stability of the intraocular lens.
This is a prospective patient-masked clinical trial. The study followed the tenets of the Helsinki agreement, and informed consent was obtained from all patients. In this study, 40 eyes from 20 patients were recruited in the Eye Hospital of Wenzhou Medical University. One patient was excluded because of a postoperative retinal tear and did not complete the follow-up protocol. The inclusion criteria included: cataract patients with extremely high myopia (axial length >27 mm); the difference between bilateral eyes was less than 1 mm; and age range from 50 to 75 years. Preoperative assessments included slit-lamp, dilated fundus examination by an ophthalmologist. The same examiner performed noncontact tonometry and optical biometry (IOLMaster 5.0, Carl Zeiss, Germany) measurements. Patients with keratitis, glaucoma, uveitis, retinitis pigmentosa, pseudoexfoliation syndrome, diabetes, or myotonic dystrophy were excluded. Additionally, patients with history of ophthalmic surgery, trauma, severe postoperative inflammatory reactions, or unsuccessful intraoperative continuous circular capsulorhexis (CCC) were excluded.
All surgeries were performed by the same experienced surgeon (Z. Y. E). Phacoemulsification (Alcon infiniti, USA) was performed and a one-piece hydrophilic, square-edged Akreos MI60 IOL with a total length of 11 mm and optical zone diameter length 6.2 mm (Bausch, USA) was implanted. After topical anesthesia, a 2.2 mm corneal incision was made. Ophthalmic viscosurgical devices (OVDs) were used to inflate the anterior chamber, and CCC (diameter range of 5.5 ± 0.2 mm) was performed, ensured the CCC size and shape to expected use of the digital navigation system. Hydrodissection and phacoemulsification were performed, and the cortex was removed with automated irrigation/aspiration. In the polished group, take the left eye for example, after the IOL implantation, a polisher was introduced into the chamber via a side port incision on the temporal to polish the superior and nasal quadrant of the inner surface of the anterior capsule and then via a main incision on the superior to polish the inferior and temporal quadrant capsule. In the unpolished group, the anterior capsule was left unpolished. All posterior capsules were polished.
According to the random number table, one eye was randomly assigned to the polished group, while the other eye was assigned to the unpolished group, and two operations were completed within one week. All cases of postoperative medication were standardized. Immediate application of eye drops occurred after surgery. Levofloxacin (0.5%, Santen, Japan) was administered four times a day for two weeks after surgery. Fluorometholone (0.1%, Santen, Japan) was administered four times a day for 4 weeks after surgery, and the dose was reduced once a week. Bromfenac sodium (0.1%, Stuton, Japan) was administered twice a day for six weeks after surgery.
All patients were examined at one day, one week, and one, three, and six months after surgery. In every follow-up visit, BCVA and intraocular pressure were assessed. Fully dilated fundus exams were also performed. The refractive status and anterior capsule opening size were determined as baseline on the first day after operation. Measured parameters included the area and diameter of the anterior capsule opening (area and D), IOL tilt and decentration, refractive state, and postoperative aqueous depth (PAD). All exams were performed after pupil dilation with tropicamide phenylephrine (Santen, Japan). The investigator acquiring and measuring the data have been masked. Anterior-segmental photography using both diffused light and slit-light across the central visual axis was obtained from each patient. Image J software (2x, National Institutes of Health) was used to determine the anterior capsulorhexis size (Area and D).
The commercially available Scheimpflug imaging system (Pentacam, Oculus) was used to measure the PAD, which is defined as the perpendicular distance from the central corneal endothelium to the anterior surface of IOL. The Pentacam Scheimpflug system also was used to measure IOL tilt and decentration [
Anterior segment of an aphakic eye imaged by the Pentacam Scheimpflug imaging system. L3: axis on the optical center of IOL; L4: axis on the center of pupilla; C1: the best-fit-circle on the anterior surface of IOL; C2: the best-fit-circle on the posterior surface of IOL; L1: horizontal line of IOL; L2: horizontal line of pupilla. The tilt of IOL is defined as the angle between L3 and L4. The decentration of IOL is defined as the distance between horizontal coordinates of P1 and P2.
Data analysis was performed using SPSS software for Windows (Version 19.0; SPSS Inc., Chicago, IL, U.S.). Kolmogorov–Smirnov tests were used to check the normal distribution of variables. Based on the design of experiment, paired
A total of 38 eyes (19 patients) with mean age of 60.53 ± 10.18 years were included in this prospective study. No patients received Nd: YAG laser capsulotomy due to serious posterior capsule opacification (PCO) or CCS. There were no significant differences between the polished group and the unpolished group, in terms of the axial length (AL), refraction status, and anterior capsule opening size on the day after surgery (Table
The AL, refraction status, and anterior capsule opening size at the 1st day after surgery.
Parameter ( |
Polished | Unpolished |
|
|
---|---|---|---|---|
AL (mm) | 29.90 ± 1.68 | 29.99 ± 1.86 | −0.544 | 0.583 |
Refraction status (D) | −3.05 ± 0.91 | −2.70 ± 1.06 | −1.347 | 0.195 |
Area (mm2) | 25.26 ± 1.21 | 25.46 ± 1.40 | −1.008 | 0.327 |
Vertical Dia.(mm) | 5.45 ± 0.12 | 5.50 ± 0.10 | −1.644 | 0.118 |
Horizontal dia. (mm) | 5.48 ± 0.10 | 5.51 ± 0.09 | −1.509 | 0.149 |
Although the IOL tilt did not show significant differences between groups at one month after operation (
Cross-sectional comparison between polished and unpolished groups at the 1 month after surgery.
Parameter ( |
Polished | Unpolished |
|
|
---|---|---|---|---|
Refraction status (D) | −3.00 ± 0.77 | −2.76 ± 1.12 | −1.124 | 0.276 |
PAD (mm) | 4.79 ± 0.39 | 4.79 ± 0.39 | 0.076 | 0.940 |
IOL tilt (°) | 0.49 ± 0.30 | 1.06 ± 0.90 | −0.364 | 0.065 |
IOL decentration (mm) | 0.32 ± 0.16 | 0.38 ± 0.19 | −0.973 | 0.344 |
Area (mm2) | 23.97 ± 1.34 | 23.78 ± 2.11 | 0.495 | 0.626 |
Vertical dia. (mm) | 5.38 ± 0.17 | 5.38 ± 0.27 | 0.026 | 0.979 |
Horizontal dia. (mm) | 5.37 ± 0.15 | 5.32 ± 0.22 | 1.208 | 0.243 |
Cross-sectional comparison between polished and unpolished groups at the 3 months after surgery.
Parameter ( |
Polished | Unpolished |
|
|
---|---|---|---|---|
Refraction status (D) | −2.92 ± 0.74 | −2.76 ± 1.03 | −0.763 | 0.455 |
PAD (mm) | 4.86 ± 0.41 | 4.87 ± 0.40 | −0.138 | 0.891 |
IOL tilt (°) | 0.61 ± 0.41 | 1.13 ± 1.02 | −2.127 | 0.047 |
IOL decentration (mm) | 0.37 ± 0.17 | 0.49 ± 0.22 | −2.154 | 0.045 |
Area (mm2) | 23.41 ± 1.24 | 22.97 ± 2.14 | 1.018 | 0.322 |
Vertical dia. (mm) | 5.35 ± 0.20 | 5.32 ± 0.25 | 0.527 | 0.605 |
Horizontal dia.(mm) | 5.31 ± 0.16 | 5.26 ± 0.26 | 0.773 | 0.450 |
Cross-sectional comparison between polished and unpolished groups at the 6 months after surgery.
Parameter ( |
Polished | Unpolished |
|
|
---|---|---|---|---|
Refraction status (D) | −2.97 ± 0.74 | −2.99 ± 1.11 | −0.127 | 0.900 |
PAD (mm) | 4.87 ± 0.47 | 4.81 ± 0.42 | 0.645 | 0.527 |
IOL tilt (°) | 0.69 ± 0.35 | 1.24 ± 1.00 | −2.519 | 0.021 |
IOL decentration (mm) | 0.42 ± 0.14 | 0.55 ± 0.21 | −2.519 | 0.021 |
Area (mm2) | 23.26 ± 1.24 | 22.64 ± 1.90 | 1.636 | 0.119 |
Vertical dia. (mm) | 5.33 ± 0.18 | 5.26 ± 0.24 | 1.452 | 0.164 |
Horizontal dia.(mm) | 5.28 ± 0.17 | 5.17 ± 0.25 | 1.563 | 0.135 |
The anterior capsular opening area decreased significantly between each time points (all
The differences in IOL stability between the two groups (
The differences in refraction and anterior capsule opening size between the two groups.
The anterior capsular opening area differed significantly between each time points (
The risk of postoperative complications, such as ACCS, is increased in high myopic patients due to zonular weakness. This is caused by anterior capsular opening shrinkage, zonule elongation, or IOL tilt and decentration. In a previous retrospective analytical study, we demonstrated that the frequency of anterior capsular opening shrinkage and IOL tilt and decentration was significantly higher in cataract eyes with high myopia than that in cataract eyes with a normal axial length [
No significant difference in the anterior capsule opening formation between the two groups was observed. However, we found the anterior capsule opening area of the two groups similarly contracted after the operation. This is due to myofibrillar contraction of LECs following transdifferentiation [
The impact of IOL tilt and decentration on visual quality has been widespread recognized [
In this study, using the Pentacam system to evaluate the PAD, we defined the PAD as the distance from the posterior surface of the corneal to the anterior IOL surface. This reflects the ELP, which has a clinically relevant impact on postoperative refraction [
Besides, during the six months follow-up even beyond the experiment, we observed no obvious difference in the incidence of PCO between polished eyes and unpolished eyes which was consistent with the results of the previous study of Liu et al. [
The limitation of this study is relatively small sample size and some differences, which has not reached any significant clinical impact in terms of patient symptoms. However, in the present study, all procedures were performed by the same surgeon, and the axial length of our subjects was limited to more than 27; the difference between bilateral eyes was less than 1 mm, and these may minimize influencing factors.
In conclusion, our study suggests that 360° anterior capsule polishing can effectively maintain stability of the position of the IOL-capsule complex.
This prospective study was approved by the Research Review Board at Wenzhou medical University. Practices and research were in accordance with the tenets of the Declaration of Helsinki.
Written informed consent was obtained from all the patients after explanation.
The authors declare that they have no conflicts of interest.
Dandan Wang and Xiaoyu Yu contributed equally to this work.
This study was supported by research grants from the Provincial Construction Project of Zhejiang (Grant no. 201647538), the Innovation Discipline of Zhejiang Province (lens disease in children), and research grants from the Science and Technology Projects of Wenzhou, Zhejiang (Grant no. 20160452).