Optical coherence tomography for an in-vivo study of posterior-capsule-opacification types and their influence on the total-pulse energy required for Nd:YAG capsulotomy: a case series

A 3D in vitro model for assessing the influence of intraocular lens: Posterior lens capsule interactions on lens epithelial cell responses

Posterior Capsule Opacification (PCO), the most frequent complication of cataract surgery, is caused by the infiltration and proliferation of lens epithelial cells (LECs) at the interface between the intraocular lens (IOL) and posterior lens capsule (PLC). According to the "no space, no cells, no PCO" theory, high affinity (or adhesion force) between the IOL and PLC would decrease the IOL: PLC interface space, hinder LEC migration, and thus reduce PCO formation. To test this hypothesis, an in vitro hemisphere-shaped simulated PLC (sPLC) was made to mimic the human IOL: PLC physical interactions and to assess their influence on LEC responses. Three commercially available IOLs with different affinities/adhesion forces toward the sPLC, including Acrylic foldable IOL, Silicone IOL, and PMMA IOL, were used in this investigation. Using the system, the physical interactions between IOLs and sPLC were quantified by measuring the adhesion force and interface space using an adhesion force apparatus and Optical Coherence Tomography, respectively. Our data shows that high adhesion force and tight binding between IOL and sPLC contribute to a small interface space (or "no space"). By introducing LECs into the in vitro system, we found that, with small interface space, among all IOLs, acrylic foldable IOLs permitted the least extent of LEC infiltration, proliferation, and differentiation (or "no cells"). Further statistical analyses using clinical data revealed that weak LEC responses are associated with low clinical PCO incidence rates (or "no PCO"). The findings support that the in vitro system could simulate IOL: PLC interplays and predict IOLs' PCO potential in support of the "no space, no cells, no PCO" hypothesis.

Analysis of the capsular bend in posterior capsular opacification using anterior segment optical coherence tomography

PURPOSE

To investigate the link between the capsular bend and the morphological types and characteristics of posterior capsular opacification (PCO) using anterior segment optical coherence tomography.

METHODS

Thirty eyes with PCO were examined, and three types of PCO were identified: pearl, fibrosis, and mixed. We assessed anterior capsular overlap, intraocular lens-capsule adhesion, and capsular bending. In addition to measuring the intraocular lens-posterior capsule distance and capsule bending angle (CBA), the PCO parameters (area, density, and score at 6-, 5-, and 3-mm intraocular lens optic regions) were recorded. The associations between capsular bend and PCO type and characteristics were investigated. A control group of 12 eyes without PCO was used to compare the study variables.

RESULTS

With p values greater than 0.001, there was a statistically significant difference in the mean PCO area and score at the 6-, 5-, and 3-mm optic zones in different PCO types, with the pearl type having the highest value, followed by the mixed type, and finally the fibrosis type. The PCO group had a significantly higher mean CBA than the control group (P = 0.001). CBA was positively related to intraocular lens-posterior capsule distance, PCO area, and PCO score at the 6-, 5-, and 3-mm zones (P = 0.001). The receiver operating characteristic curve's cut-off point for CBA was 96.85° when comparing PCO cases to controls. Partial overlap and incomplete adhesion were statistically more common in the PCO eyes than in the control (P = 0.001, 0.003, respectively).

CONCLUSION

PCO types and CBA have a strong relationship with PCO score and intraocular lens-posterior capsule space. In PCO's eyes, CBA has a cut-off value of 96.85°.

The Influence of Inflammation in Posterior Capsule Opacification Development

Cataract represents the reduction of the transparency of the crystalline lens. Cataract surgery is the most commonly performed surgical procedure worldwide. One of the most common postoperative complication of successfully performed cataract surgery is a development of posterior capsule opacification (PCO). In the postoperative period, lens epithelial cells (LECs) undergo proliferation, migration and differentiation, which is clinically manifested by the development of PCO. Inflammation has a central role in these processes. Cytokines, such as transforming growth factor β, fibroblast growth factor, interleukin 1, interleukin 6, matrix metalloproteinases have a huge effect on the activity of LECs. Understanding these processes can find a great usage in clinical practice. By prescribing anti-inflammatory therapy in the early postoperative period, the incidence of PCO can be significantly reduced.

[Posterior YAG capsulotomy: selection of the application pattern]

BACKGROUND

The posterior neodymium-yttrium-aluminum-garnet laser capsulotomy is an established and simple method with a low complication rate for the treatment of secondary cataracts; however, the risk of intraocular pressure elevation, pit marks of the intraocular lens (IOL), anterior hyaloid damage, cystoid macular edema and retinal detachment may increase with high pulse number, pulse energy, and total energy.

PURPOSE

The optimization potential of the method through a rational choice of the laser pattern and the strategy, taking into account the mechanical properties of the posterior capsule and the anatomical features of the retrolental region, is shown.

MATERIAL AND METHODS

The article provides a literature review with own clinical observations and a geometric representation.

RESULTS

The efficiency of a laser pattern is examined with a constant capsulotomy length: The largest opening can be reached with the U‑pattern, which is followed by the +, T, H, V, O and spiral patterns in decreasing order. When estimating the size of the opening, its incircle is of particular functional importance. If the ability of the posterior capsule to tear spontaneously, which is predetermined by its anatomical and mechanical properties, is taken into account when choosing the application pattern and the laser strategy, the efficiency of the method increases.

CONCLUSION

An efficient technique is not only determined by an adapted defocusing and a minimum possible individual pulse energy setting but also characterized by the lowest possible total energy consumption if the necessary opening size is achieved by the smallest number of pulses. Taking into account the individual retrolental anatomical conditions and the mechanical properties of the NS membrane can contribute to the gentle implementation of a YAG capsulotomy.

Utility of the optical quality analysis system for decision-making in Nd: YAG laser posterior capsulotomy in patients with light posterior capsule opacity

Background

A prospective cohort study was performed to evaluate whether the Optical Quality Analysis System (OQAS) can serve as a valuable additional indicator for appropriate posterior capsulotomy referral.

Methods

One hundred and five eyes from 96 patients undergoing capsulotomy were divided into precapsulotomy logMAR CDVA ≤0.1 group and logMAR CDVA > 0.1 group. CDVA, and the Visual Function 14 index (VF-14) score were estimated before and 1 month after capsulotomy. The objective scattering index (OSI) value was measured by using the OQAS. Posterior capsule opacification (PCO) severity was assessed with Evaluation of PCO 2000 (EPCO 2000) software.

Results

In logMAR CDVA > 0.1 group, the correlations of OSI, logMAR CDVA, EPCO score and VF-14 score were very strong preoperatively. In logMAR CDVA ≤0.1 group, preoperatively, OSI was correlated with logMAR CDVA (r = 0.451), EPCO score (r = 0.789), and VF-14 score (r = 0.852). LogMAR CDVA has weak correlation with VF-14 score (r = − 0.384) and EPCO score (r = 0.566). VF-14 score was correlated with EPCO score (r = − 0.669). In the logMAR CDVA ≤0.1 group, there was no significant difference in logMAR CDVA between precapsulotomy and postcapsulotomy (P > 0.05). In the two groups, all the other optical quality parameters were significantly improved after capsulotomy (P < 0.05). In logMAR CDVA > 0.1 group, the area under the curve of the ROC of the OSI was 0.996 (P = 0.000). In logMAR CDVA ≤0.1 group, the area under the curve of the ROC of the OSI was 0.943 (P = 0.000).

Conclusions

The OSI was useful for evaluating of PCO and prediction of beneficial capsulotomy. Especially for patients with slight PCO and better visual acuity, OSI is more valuable than CDVA and completely objective examination.

Trial registration

The study protocol was registered at the Chinese Clinical Trial Registry. Register: ChiCTR1800018842 (Registered Date: October 13th, 2018).

[Late capsular block syndrome]

The article describes 5 cases of capsular block syndrome (CBS). This late cataract surgery complication has not been sufficiently covered in Russian scientific literature. Diagnostics were based mainly on slit-lamp biomicroscopy and anterior segment optical coherence tomography. In all cases, examination revealed a retro-optical space filled with content of different transparency and homogeneity (transparent liquid, opaque liquid, regenerative lens material). The condition caused visual acuity to decrease in each case. Patient management included follow-ups (2 cases), yttrium-aluminum-garnet laser (YAG-laser) puncture of posterior lens capsule (1 case) or YAG-laser posterior capsulotomy (2 cases). YAG-laser treatment resulted in visual functions improvement.

Application of Spectral Domain Optical Coherence Tomography to Objectively Evaluate Posterior Capsular Opacity In Vivo

Objectives

To objectively evaluate posterior capsular opacification (PCO) with RTVue-100 spectral domain-OCT and assess the agreement with the Pentacam system.

Methods

Sixty-seven eyes diagnosed with PCO were included. RTVue-100 SD-OCT was used to scan the IOL outline and PCO at horizontal and vertical meridians. PCO was also imaged with a Pentacam and slit-lamp photography system. With RTVue-100 SD-OCT, the PCO area, thickness, density, and objective scores were recorded and used to evaluate the severity of PCO at 3 mm and 5 mm diameter ranges of the IOL optic region. We assessed the correlation of visual acuity, PCO characteristics, and PCO scores. PCO scores acquired from RTVue-100 SD-OCT images were also compared with those from the Pentacam. Differences between pear-type and fibrosis-type PCOs were also compared using RTVue-100 SD-OCT cross-sectional images.

Results

The cross-sectional images of PCO acquired with RTVue-100 SD-OCT corresponded well to Pentacam and slit-lamp retroillumination images. IOL-posterior capsular space, area, thickness, and density of the proliferated and accumulated LECs could be clearly visualized and quantified with RTVue-100 SD-OCT. PCO scores were correlated with decreased visual acuity, which was in line with the outcomes using the Pentacam. Differences between the pear-type and fibrosis-type PCO were statistically significant; pear-type PCOs showed a wider and thicker opacification region with lower density compared with fibrosis-type PCOs.

Conclusion

RTVue-100 SD-OCT could be a powerful tool in PCO objective evaluation and classification. OCT could be used to visualize the morphology and outline of PCO. Thus, it could discriminate and quantify differences between different types of PCO. PCO scores seem to be a useful factor that could reliably reflect PCO severity.

Surface PEGylation of intraocular lens for PCO prevention: An in vivo evaluation

Posterior capsular opacification (PCO) is a common complication in cataract surgery. The development of PCO is attributed to the combination of adhesion, migration, proliferation, and transdifferentiation of the residual lens epithelial cells (LEC) onto the interface of intraocular lens (IOL) material and lens posterior, in which the initial adhesion is the beginning step and plays important roles. In the present study, hydrophilic polyethylene glycol (PEG) was immobilized onto IOL surface via plasma-aided chemical grafting procedure. The attenuated total reflection - Fourier transform infrared (ATR-FTIR) and contact angle (CA) - measurements indicate the successful surface PEGylation, as well as the excellent hydrophilicity of the surfaces. Compared with pristine IOL, the PEGylation does not influent its optical property, whereas the initial adhesion of LEC is greatly inhibited. In vivo ocular implantation results show that the PEGylated IOL presents good in vivo biocompatibility, and can effectively prevent the PCO development.