Intraocular pressure before and after capsulorhexis using two viscoelastic substances and two surgical approaches in enucleated porcine eyes

AIM:To investigate the influence of ophthalmic viscoelastic devices(OVDs)and different surgical approaches on the intraocular pressure(IOP)before and after creation of the curvilinear circular capsulorhexis(CCC)as a measure for anterior chamber stability during this maneuver.METHODS:Prospective experimental WetLab study carried out on enucleated porcine eyes.IOP was measured before and after CCC with the iCare Rebound tonometer(iCare ic200;iCare Finland Oy,Vantaa,Finland).The OVDs used were a cohesive one[Z-Hyalin,Carl Zeiss Meditec AG,Germany;hyaluronic acid(HA)]and a dispersive[Z-Celcoat,Carl Zeiss Meditec AG,Germany;hydroxy propylmethylcellulosis(HPMC)].The CCC was created using Utrata forceps or 23 g microforceps in different combinations with the OVDs.RESULTS:Using the Utrata forceps the IOP dropped from 63.65±6.44 to 11.25±3.63 mm Hg during the CCC.The use of different OVDs made no difference.Using the 23 g microforceps the IOP dropped from 65.35±8.15 to 36.55±6.09 mm Hg.The difference between IOP drop using either Utrata forceps or 23 g microforceps was highly significant regardless of the OVD used.CONCLUSION:Using the sideport for the creation of the capsulorhexis leads to a lesser drop in IOP during this maneuver compared to the main incision in enucleated porcine eyes.The use of different OVD has no significant influence on IOP drop.

Clinical Observation of Non-Staining Circular Capsulorhexis for Hypermature Cataract

Objective:To explore the circular capsulorhexis method and its clinical effect in phacoemulsification of hypermature cataract without staining.Methods:In this prospective randomized case-control study,22 patients(22 eyes)with hypermature cataract were randomly divided into a staining agent group(10 cases,10 eyes)and a non-staining agent group(12 cases,12 eyes).Both groups underwent phacoemulsification with foldable intraocular lens implantation under topical anesthesia.In the staining agent group,0.5%indocyanine green was used to stain the anterior lens capsule to assist in circular capsulorhexis;in the non-staining agent group,after puncturing the anterior lens capsule and aspirating the liquefied cortical material,the capsular bag was filled with viscoelastic agent to increase the contrast prior to circular capsulorhexis.The operability of the anterior capsule without staining in capsulorhexis was observed,and the effect of capsulorhexis,diameter of capsulorhexis opening,and operative time were compared and analyzed between the two groups.Results:Both groups successfully underwent circular capsulorhexis,with a success rate of 100%.The diameters of capsulorhexis opening in the staining agent group and non-staining agent group were 5.68±0.15 mm and 5.54±0.16 mm,respectively,without any statistical difference between the groups(P>0.05);the operative time of the staining agent group(40.40±5.42 s)was shorter than that of the non-staining agent group(50.92±3.97 s),and the difference was statistically significant(P<0.001).In both groups,phacoemulsification was successful,and intraocular lens were implanted into the capsular bags;their visual acuity showed significant improvement during the 1-month follow-up period after surgery,without any surgical complications.Conclusion:In hypermature cataract,injecting viscoelastic agent into the capsular bag for volume replacement,given a lack of capsule staining agent,can increase the contrast for capsulorhexis and reduce the risk of large capsular bag collapse on the zonular ligament.Thus,it is considered safe and effective.Circular capsulorhexis is conducive to a smooth phacoemulsification procedure.

A new application of capsulorhexis forceps in phacoemulsification: capsulorhexis forceps-assisted prechop technique

Dear Editor,I am Dr.Jian-Cen Tang,from the Department of Ophthalmology,Shanghai East Hospital,Tongji University School of Medicine,Shanghai.I write to present a new application of capsulorhexis forceps in phacoemulsification,which is called capsulorhexis forceps-assisted prechop technique.

Comparison of diathermic high-frequency capsulorhexis and continuous curvilinear capsulorrhexis in white cataract surgery

AIM： To compare the corneal endothelial cell counts pre-and post-operation, ultrastructure of anterior lens capsule and surgical completion after diathermic highfrequency capsulorhexis（DHC） and continuous curvilinear capsulorrhexis（CCC） applied in phacoemulsification（PHACO） of white cataract surgery.METHODS： Sixty-six eyes of 66 patients（33 males and 33 females） with cataract aged between 60 and 80 y（mean 72.5±5.5） were recruited and undergone the surgery from June 2014 to November 2016. Anterior lens capsule, derived from two kinds of capsulorhexis, were randomly divided into two groups according to random number table. The ultrastructure of the capsule edge and its closer tissue were observed by transmission electron microscopy（TEM） and optical microscopy respectively. The surgical completion conditions and corneal endothelial cell counts were analyzed pre-and post-operation after two capsulorhexis.RESULTS： The capsule derived from CCC had smooth edge, well-organized cellular structure and the cells filling into the cutting edge under TEM and optical microscopy. The capsule derived from DHC had an approximate 60 banded area of cell degeneration and necrosis, with dentiform prominences at the edge of the capsule, and no cell structure was observed at this area. The corneal endothelial cell counts of both groups were slightly declined 1 wk post-operation compared with that of preoperation. There was no statistical difference between the two groups（t=1.63, P〉0.05）.CONCLUSION： DHC shows good clinical value in white mature and hypermature cataract surgery.

Application of lens capsules tension reducing capsulorhexis and conventional capsulorhexis in the white cataract phacoemulsification

Objective: To explore the clinical effect of lens capsules tension reducing capsulorhexis and conventional capsulorhexis in the white cataract phacoemulsification. Methods: A total of 68 patients (76 eyes) with white cataract who were admitted in our hospital from June, 2011 to June, 2016 were included in the study and divided into the experiment group (n=34, 36 eyes) and the control group (n=34, 40 eyes) according to the difference of intraoperative capsulorhexis. All the patients were performed with cataract phacoemulsification in combined with intraocular lens implantation. The patients in the experiment group were performed with lens capsules tension reducing capsulorhexis, while the patients in the control group were performed with conventional capsulorhexis. The integrity of the anterior capsule capsulorhexis, the degree of corneal endothelium edema, the intraocular lens deviation, uncorrected visual acuity, and corneal endothelial cell count in the two groups were compared. Results: A total of 34 eyes (94.44%) in the experiment group and 35 eyes (87.50%) in the control group successfully completed continuous annular capsulorhexis, and there was no significant difference between the 2 groups. The number of patients whose uncorrected visual acuity was greater than 0.5 increased 1 d-6 months after operation, and that in the experiment group was significantly higher than that in the control group. The difference of intraocular lens deviation rates between the 2 groups at different times after operation was not significant. The corneal endothelial cell count 1 d-6 months after operation in the 2 groups was significantly decreased when compared with before operation, but the difference between the 2 groups was not significant. The number of eyes without edema in the experiment group 1d after operation was significantly higher than that in the control group, and the number of eyes with grade Ⅱ edema was significantly less than that in the control group. Conclusions: The method of reducing capsulorhexis can make white cataract patients get better vision after operation, and reduce the degree of corneal edema, with higher clinical application value.

Standard manual capsulorhexis / Ultrasound phacoemulsification compared to femtosecond laser-assisted capsulorhexis and lens fragmentation in clear cornea small incision cataract surgery

Background:Femtosecond-laser assisted clear cornea cataract surgery may hold promise in safer and more effective procedures.We decided to perform a comparative study to standard manual incision phacoemulsification surgery.Methods:This is a single-center,single-intervention,and prospective comparative data evaluation of 133 consecutive cases subjected to cataract surgery.Group-A(Phaco),manual capsulorhexis&ultrasound phacoemulsification(n=66);Group-B femtosecond-laser assisted capsulorhexis and lens fragmentation(n=67),employing the LenSx laser(Alcon Surgical,Ft.Worth,TX).All cases were evaluated for refraction,visual acuity,keratometry,tomography,pachymetry,endothelial cell counts,intraocular pressure,and type of intraocular lens(IOL)implanted.The groups were matched for age,gender,pre-operative vision metrics,and cataract grade,and were followed up to 1 year.Results:In group-A post-operative uncorrected distance visual acuity(UDVA)was 20/20 or better in 61.5%and 20/25 or better in 78.5%of the eyes.The femtosecond laser group-B had improved outcomes(p=0.075 and p=0.042,respectively):post-operative UDVA was 20/20 or better in 62.7%of the eyes and 20/25 or better in 85.1%.Linear regression scatterplots of achieved versus attempted spherical equivalent had excellent regression coefficients(r^(2)=0.983 in group-A and 0.979 in group-B).There were 75.2%cases in group-A and 80.6%in group-B(p=0.8732)within±0.50 D of targeted refractive equivalent.Slight trend of under-correction was noted in group-A.Average residual manifest cylinder in the toric subgroup-A was-0.50 D(95%Limit-of-Agreement(LoA)=-0.78 D),and in toric subgroup-B-0.45 D(LoA=-0.45 D).Conclusions:Mean spherical equivalent refraction and visual acuity are comparable with laser cataract surgery compared with manual capsulorhexis&ultrasound phacoemulsification.Improved astigmatism correction may be among the benefits of femtosecond laser–assisted cataract surgery.Transient corneal edema may be a first day transient disadvantage in femtosecond laser–assisted cataract surgery.

Femtosecond laser capsulotomy versus manual capsulotomy： a Meta-analysis

AIM：To perform a Meta-analysis on the precision and safety of femtosecond laser（FSL） capsulotomy compared with manual continuous curvilinear capsulotomy（CCC）.· METHODS：We searched PubMed,EMBASE,Web of Science,the Cochrane Library databases,and Clinical Trials.gov that maintained our inclusion criteria.Reference lists of retrieved articles were also reviewed.The effects of morphology of capsulorhexis and the tears of anterior capsule were calculated by using randomeffect models.· RESULTS：We identified 4 randomized and 7nonrandomized studies involving 2941 eyes.The diameter of capsulotomy and the rates of anterior capsule tear showed no statistically difference between FSL group and manual group（MD=0.03;95%CI,-0.03 to0.09,P=0.31）,and（OR=1.40;95%CI,0.28 to 6.97,P=0.68） respectively.In terms of the circularity of capsulotomy,FSL group had a more significant advantage than the manual CCC group（MD=0.09;95%CI,0.05 to 0.12,P〈0.001）.· CONCLUSION：Our Meta-analysis shows that FSL can perform a capsulotomy with more precision and higher reliability than manual CCC.The results in diameter of capsulotomy and the rate of anterior capsule tears was no significant difference between FSL and manual CCC groups.However in terms of circularity,the FSL was superior to the manual procedure.

Phacoemulsification combined with transpupillary removal of silicone oil and intracapsular intraocular lens implantation

AIM： To estimate the effectiveness of phacoemulsification and foldable intraocular lens（IOL） implantation combined with transpupillary silicone oil removal.METHODS： There were 168 eyes of 168 candidate patients with cataract and silicone oil-filled eyes recruited in our study. All of the patients received the intraocular silicone oil removal surgery by transpupillary drainage and cataract extraction by phacoemulsification. Then the IOL implantation were also performed through corneal incision. RESULTS： The surgery was successfully completed in all eyes. Best corrected visual acuity（BCVA） and postoperative complications were recorded in three months after surgery. There were 143 eyes with BCVA improved, otherwise 25 eyes remained stable at the last follow-up visit. The mean BCVA statistically improved from 20/400±0.02 to 20/100±0.15（P〈0.001） and mean postoperative IOP was 13.85±2.18 mm Hg（P=0.415）. No intra-operative complications were reported.CONCLUSION： Phacoemulsification combined with transpupillary removal of silicone oil is a safe and simple effective method. In general, it enables quick recovery of visual acuity with less complication rate.

Cell death and survival following manual and femtosecond laser-assisted capsulotomy in age-related cataract

AIM： To study molecular and morphological changes in lens epithelial cells following femtosecond laser-assisted and manually performed continuous curvilinear capsulotomy（CCC） in order to get information about these methods regarding their potential role in the induction of development of secondary cataract. METHODS： Anterior lens capsules（ALC） were removed from 40 patients with age-related cataract by manual CCC and by femtosecond laser-assisted capsulotomy（FLAC）. Samples removed by manual CCC were assorted in group 1, FLAC samples were classified in group 2. Morphology of lens epithelial cells was examined with light and electron microscopes. Following capsulotomy, expressions of p53, Bcl-2 and cyclin D1 genes were analyzed with reverse transcriptase polymerase chain reaction. Immunohistochemistry was used to detect the pro-apoptotic p53 in the epithelial cells. RESULTS： Light and electron microscopic examination showed that ALC of group 1 contained more degenerating cells following manual CCC than after FLAC. The expression level of p53 was higher after manual than laser-assisted surgery. Immunocytochemistry indicated significantly higher number of cells containing p53 protein in the manual CCC group than following FLAC. Bcl-2 and cyclin D1 gene expression levels were slightly lower following manual CCC than after FLAC, but the difference was not significant. CONCLUSION： Manually removed ALC shows slightly, but not significantly larger damage due to the mechanical stretching and pulling of the capsule than those removed using FLAC.

Experimental Study on the Effectiveness and Safety of Gardenia Blue Pigment on Anterior Capsule Staining

Objective: To explore the effect of gardenia blue pigment on the anterior capsule staining and its safety performance. Methods: In this study, New Zealand white rabbits were used as the research object to test the effect of gardenia blue pigment on the anterior capsule staining and anterior segment toxicity. In this study, gardenia blue stains of different concentrations (5%, 4%, 3%, 2%, 1%, 0.5%) were prepared to stain the anterior capsule of rabbit crystals, and the effect of the stain was observed to determine the optimal concentration of the stain. Twenty-seven healthy New Zealand white rabbits without eye disease were randomly divided into three groups: gardenia blue staining group;bio-blue positive drug group;physiological saline group. The intraocular pressure, anterior chamber inflammation, corneal endothelial injury, and anterior chamber angle pathological changes were measured in 1D, 7D, and 14D. Results: The results of this study showed that the effect of gardenia blue pigment on the anterior capsule of the lens was the best when the concentration of blue pigment was 2%. There was no change in intraocular pressure in the anterior chamber for a short period of time. There is no damage to the corneal endothelium. Conclusion: The results of this study show that the effect of gardenia blue pigment on the anterior capsule is best when the concentration of blue pigment is 2%, and the stain has no obvious toxic and side effects on the anterior segment of the eye.

Femtosecond laser-assisted cataract surgery(FLACS)in resident training

This article reviews the history of the femtosecond laser in ophthalmology and its subsequent introduction into the field of cataract surgery.It discusses the innovations that this technology has brought to the field.The article also describes the current system of teaching cataract surgery to ophthalmology residents in the United States and then examines how femtosecond laser-assisted cataract surgery(FLACS)can be a beneficial part of residency education.

Research progress of lens zonules

Background:The lens zonule,a circumferential system of fibres connecting the ciliary body to the lens,is responsible for centration of the lens.The structural,functional,and positional abnormalities of the zonular apparatus can lead to the abnormality of the intraocular structure,presenting a significant challenge to cataract surgery.Main text:The lens zonule is the elaborate system of extracellular fibers,which not only centers the lens in the eye but also plays an important role in accommodation and lens immunity,maintains the shape of the lens,and corrects spherical aberration.The zonules may directly participate in the formation of cataract via the immune mechanism.Abnormal zonular fibers that affect the position and shape of the lens may play an important role in the pathogenesis of angle closure disease and increase the complexity of the surgery.Capsular tension rings and related endocapsular devices are used to provide sufficient capsular bag stabilization and ensure the safety of cataract surgery procedures.Better preoperative and intraoperative evaluation methods for zonules are needed for clinicians.Conclusions:The microstructure,biomechanical properties,and physiological functions of the lens zonules help us to better understand the pathogenesis of cataract and glaucoma,facilitating the development of safer surgical procedures for cataract.Further studies are needed to carefully analyze the structure–function relationship of the zonular apparatus to explore new treatment strategies for cataract and glaucoma.

Finite element analysis of neodymium： yttrium-aluminum-garnet incisions for the prevention of anterior capsule contraction syndrome

Background Anterior capsular contraction syndrome is a potential complication of continuous curvilinear capsulorhexis （CCC）. Three neodymium： yttrium-aluminum-garnet （Nd：YAG） laser relaxing incisions decrease anterior capsular contraction but the mechanism is unknown. The present study analyzed the biomechanical mechanism of three Nd：YAG laser relaxing incisions made to reduce anterior capsular contraction. Methods A three-dimensional control model and a three-dimensional Nd：YAG model of the anterior capsule with an opening diameter of 6 mm were created. Three incisions of 1 mm in length were made centrifugally at intervals of 120~ around the opening circle. The stress alterations of the anterior capsule after CCC with and without Nd：YAG relaxation were numerically simulated and compared. Results In the control model, the stress was axially uniform in the inner area and relatively high near the inner rim of the opening. Meanwhile, in the Nd：YAG model, the stress level was very low in the inner opening areas, especially near the three incisions. The relaxing incisions in the Nd：YAG model significantly released the relatively high stress on the anterior capsule. Additionally, there was a high stress gradient near the relaxing incisions. Conclusion Biomechanical effects of stress release may be the preventive mechanism of Nd：YAG incision against anterior capsular contraction syndrome.

Femtosecond laser cataract surgery

Femtosecond laser(FSL)cataract surgery is in its infancy but is rapidly gaining popularity due to the improved consistency and predictability for corneal incisions and anterior capsulorhexis.It enables subsequently less phacoemulsification energy and time to be employed,which has gains in terms of reduced corneal oedema.In addition,the FSL allows better circularity of the anterior capsulotomy,capsule overlap,intraocular lens(IOL)placement and centration of the IOL.These advantages have resulted in improved visual and refractive outcomes in the short term.Complication rates are low which reduce with surgeon experience.This review article focuses on the Alcon LenSx system.