The Effect of Capsular Tension Ring on Posterior Capsular Opacity in Cataract Surgery

Can toric IOL rotation be minimized? Toric IOL-Capsular Tension Ring suturing technique and its clinical outcomes

Purpose: In this study, we aimed to evaluate the outcomes of the toric intraocular lens (IOL) and capsular tension ring (CTR) suturing technique in patients with cataract and astigmatism. Methods: Group 1 comprised 37 eyes of 36 patients to whom the CTR-toric IOL complex was co-implanted after the CTR was sutured to the toric IOL haptic. Group 2 comprised 35 eyes of 33 patients in whom the toric IOL and CTR were implanted without suturing. Both groups were compared in terms of preoperative and postoperative astigmatism, best-corrected visual acuity (BCVA), uncorrected visual acuity (UCVA), and IOL rotation. Results: The mean rotation degree was 0.54° ± 2.29° in group 1 and 4.28° ± 8.84° in group 2 (p = .01). While there was no significant difference between the postoperative residual astigmatism and the estimated residual astigmatism in group 1, the postoperative residual astigmatism was statistically higher than the estimated residual astigmatism in group 2 (p = .47 and 0.000, respectively). The mean postoperative UCVA was 0.02 ± 0.04 (logMAR) in group 1 and 0.08 ± 0.13 (logMAR) in group 2 (p = .01). Conclusion: The toric IOL and CTR suturing technique provides excellent rotational stability and astigmatism correction.

Exosome-transmitted circ-CARD6 facilitates posterior capsule opacification development by miR-31/FGF7 axis

BACKGROUND

Posterior capsular opacification (PCO) is the major vision-disrupting complication arising after cataract surgery. Circular RNAs (circRNAs) are biological active RNAs which were involved in various physiological functions. So far, the role of circRNA caspase recruitment domain family member 6 (circ-CARD6) in PCO is still unclear.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was applied to detect the expression of circ-CARD6, microRNA 31 (miR-31) and fibroblast growth factor 7 (FGF7) message RNA (mRNA). Western blot was used to analyze the protein expression. Transmission electron microscopy (TEM) was employed to capture the exosome image. The proliferation and metastasis were analyzed by cell counting kit-8 (CCK8), transwell and wound healing assays. The potential binding sequences between miR-31 and circ-CARD6 or FGF7 were respectively predicted by Circinteractome and Targetscan online tool, and verified by dual-luciferase reporter and RNA binding protein immunoprecipitation (RIP) assays.

RESULTS

Exosome-transmitted circ-CARD6 was highly expressed in PCO tissues and TGF-β2-treated SRA01/04 cells. Circ-CARD6 deletion repressed the proliferation, metastasis, EMT process and MAPK pathway, which was reversed by anti-miR-31 in TGF-β2-treated SRA01/04 cells. Meanwhile, circ-CARD6 sponged miR-31 which directly targeted FGF7 in TGF-β2-treated SRA01/04 cells. FGF7 overexpression allayed miR-31 overexpression-induced suppression in proliferation, metastasis, EMT process and MAPK pathway. Besides, circ-CARD6 regulated FGF7 expression by sponging miR-31.

CONCLUSION

Circ-CARD6 promoted PCO development via miR-31/FGF7 axis. This finding might contribute to the development of the targeted therapy for PCO.

The effect of capsule tension ring on posterior capsule opacification: A meta-analysis

Background

Posterior capsule opacification is one of the most common complications after cataract surgery. Studies have suggested that the introduction of a capsule tension ring might play a critical role in the prevention of capsule opacification, yet quantitative evidence is still lacking. This work consists of a meta-analysis on available data in order to explore the influence of a capsule tension ring on posterior capsule opacification.

Methods

A comprehensive review of the literature on capsule tension ring and posterior capsule opacification was carried out using the Embase, Pubmed, Web of Science, and Cochrane electronic databases. The selected studies included randomized controlled trials, retrospective studies and prospective studies published before June 2020. The studies of interest were selected by two reviewers independently from the included studies. Odds ratios (ORs) and standardized mean differences (SMD) were used in order to assess the association. A fixed-effects model or a random-effects model was applied to combine data according to heterogeneities. Sensitivity analysis was used to assess the heterogeneity of the studies. Publication bias was estimated using the Egger test. Statistical analysis was performed using the stata15.1 software.

Results

The meta-analysis included in total 8 studies involving 379 cases and 333 controls. There was a statistically significant difference of Nd:YAG laser capsulotomy rate (OR=0.241, 95% CI: 0.145, 0.400 I²=42.1%) between the capsule tension ring group and the control group, indicating that the tension ring reduced the Nd:YAG laser capsulotomy rate. Further studies with continuous data also revealed that the use of capsule tension ring was associated with a lower posterior capsule opacification score (SMD = -1.402, 95% CI: -2.448, -0.355 I²=95.0%). The sensitivity analysis suggested that the result of the re-combined analysis did not change notably, indicating that the result was reliable and stable. Both pooled analysis showed no evidence of publication bias.

Conclusion

The findings of this meta-analysis confirmed that capsule tension ring might reduce capsule opacification. Further studies should be made to validate the result.

Autoregenerative redox nanoparticles as an antioxidant and glycation inhibitor for palliation of diabetic cataracts

Diabetic cataracts (DCs) are one of the most common ocular complications of diabetes, and easily causes blindness among diabetics. However, there are limited drugs to delay and prevent DCs. Research studies indicate that oxidative damage of the crystalline lens and nonenzymatic glycosylation of the lens protein play a key role in the pathogenesis of DCs. Hence, we developed a kind of autoregenerative redox nanoparticle, which was CeO2 NPs coated with PEG-PLGA (PCNPs). We first found that PCNPs could work not only as an antioxidant to protect lens epithelial cells from oxidative stress based on the repetitive elimination of reactive oxygen species (ROS), but also as a glycation inhibitor effectively restraining α-crystallin glycation and crosslinking, thereby keeping the lens transparent and alleviating DCs. Experimental results successfully validated the fact that the PCNPs were able to operate in eyes for a long time to attenuate lens opacity. We expect that this strategy will provide promising potential for the treatment of DCs.

Calculation of posterior chamber intraocular lens (IOL) size and dioptric power for use in pet rabbits undergoing phacoemulsification

OBJECTIVES

To calculate the size and dioptric power of a posterior chamber intraocular lens (IOL) to achieve emmetropia in adult rabbits and to compare the dioptric power calculation results using a proprietary predictive formula to a retinoscopy-based method.

ANIMALS STUDIED

Three wild rabbit cadavers, seven pet rabbits with cataracts and ten healthy pet rabbits.

MATERIALS AND METHODS

Implant size was calculated using a capsular tension ring (CTR) (Acrivet^® , Berlin, Germany). Published and cadaveric biometric data were used in the predictive formula. An IOL power-escalation study compared the predicted values to the refraction results of one pet rabbit (P1) fitted with a + 41D canine IOL (Acrivet^® ) and six pet rabbits (P2-P7) fitted with prototype IOLs (Acrivet^® ). Retinoscopy of 10 healthy pet rabbits served as controls.

RESULTS

A 13.5 mm CTR fitted in all rabbits and permitted the use of a 13 mm IOL. The predicted IOL power ranged between +24D and +25D. The +41D IOL resulted in a refraction error of +8D. Progressive recalculation through a calibration formula led to the insertion of three +49D IOLs in two pet rabbits and a refraction of +6D to +8D, followed by seven +58D IOLs in four pet rabbits and a refraction median of 0D (range: -1.5D to +1D).

CONCLUSIONS

A 13 mm prototype IOL of +58D achieves emmetropia and is of adequate size for rabbits. The combined use of a CTR and retinoscopy is a useful method to calculate the size and refractive power of a new, species-specific, veterinary IOL.

Influence of capsular tension ring on posterior capsule opacification in myopic eyes

Purpose:

To determine the effect of a capsular tension ring (CTR) implantation in preventing posterior capsular opacification (PCO) after cataract surgery in patients with high myopia.

Materials and Methods:

In this prospective single-surgeon standardized-surgical-procedure fellow-eye comparison trial, 34 patients with high myopia had phacoemulsification surgery. Although one eye received an acrylic intraocular lens (IOL) and CTR, other eye received only an IOL as control. PCO, within the capsulorhexis overlap, was documented by standardized digital retroillumination images at least 2 years post-operatively, and the percentage area of PCO was scored (scale 0%-100%) using the POCOman software system. The PCO score and the incidence of neodymium-doped yttrium aluminum garnet (Nd: YAG) capsulotomy of groups, and correlations between PCO score and presence of CTR, age, phaco time, refraction, and axial length (AL) were determined.

Results:

The mean time interval from surgery to PCO measurement was 43.4 ± 11.2 months for the eyes with a CTR and 43.1 ± 11.6 months for the controls (P = 0.91). The PCO score of the eyes with a CTR was significantly lower than in the controls (5.9 ± 4.3 vs. 22.3 ± 12.2, respectively; P < 0.001). There were statistically insignificant correlations between PCO score and pre-operative refraction (r = 0.02; P = 0.90), AL (r = 0.03; P = 0.80), phaco time (r = 0.11; P = 0.53), and patient's age (r = 0.23; P = 0.55). No patient with a CTR had a Nd: YAG laser capsulotomy, but it was six in controls (P = 0.025).

Conclusions:

CTR implantation seems to be effective in reducing the PCO and Nd: YAG laser capsulotomy rates in high myopic eyes.

Prevention of lens epithelial cell growth in vitro using mibefradil-containing PLGA micro particles

The prevention of the posterior capsule opacification is still unsolved. To interfere with proliferating cells the T-type calcium channel antagonist Mibefradil was immobilized in poly-lactic-co-glycolic-acid micro particles which were fixed at a capsular tension ring and tested in a human organ culture model as well as in human lens cells HLE-B3 in vitro. It is feasible to get a release significantly affecting cell viability and growth evaluated by MTT test and cell cycle analysis. In addition, Bionas^® sensor chips were used for time-dependent adhesion experiments in living lens cells. Interestingly, the concentration of Mibefradil which inhibited subconfluent cells is not effective in confluent cells. This is an important feature for the protection of the intact tissue in the eye.