Intraocular lens exchange or explantation post cataract surgery

AIM:To report incidence,indications,and visual outcomes of intraocular lens(IOL)exchange/explantation surgery.METHODS:Retrospective analysis of 60 eyes requiring IOL exchange/explantation surgery between 1^(st) January 2017 and 31^(st) December 2022.The overall outcomes as well as comparison between the trainee versus experienced surgeons were analyzed.RESULTS:Out of 39778 cataract surgeries(with no preexisting ocular co-morbidities)during a six-year period(2017-2022),60(0.15%)needed IOL exchange/explantation.Surgeons-under-training performed 36/60 cases(60%)while 24/60(40%)were by experienced surgeons.The commonest indication was subluxated IOL in 26(43.3%),followed by dislocated IOL in 20(33.3%),postoperative refractive surprise in 7(11.6%),IOL induced uveitis in five and broken haptic in two eyes.Twenty-four(40%)eyes had intraoperative complications during primary surgery.Posterior chamber IOL(PCIOL)was the commonest secondary IOL in 21(35%)eyes,scleral fixated in 20(31.6%),anterior chamber IOL(ACIOL)in 13(21.6%),iris fixated IOL in three(5%)and three eyes(5%)were left aphakic.The mean time between primary and secondary surgery was 168d(168±338.8).Best corrected visual acuity(BCVA)of>20/60 was obtained in 43 eyes(71.66%),20/80-20/200 in 14(23.33%),20/250 in two and hand movements in one.No statistically significant difference in visual outcome was noted at post-op one month between trainees versus experienced surgeons(UCVA 0.45±0.29 vs 0.53±0.32,P=0.20,BCVA 0.34±0.25 vs 0.37±0.26,P=0.69).CONCLUSION:IOL subluxation as the commonest indication and posterior capsular rupture is the commonest intraoperative risk factor.This complication can be effectively addressed with selection of the appropriate secondary IOL achieving good visual outcomes in over 70% of patients.

Early clinical outcome with lens position adjustment following implantable collamer lens surgery

AIM:To observe early clinical outcome with lens position adjustment following the implantable collamer lens(ICL)surgery.METHODS:Sixty patients were selected for this retrospective study.One eye from each patient received Toric ICL for astigmatism correction,and the other received non-astigmatic ICL surgery using horizontal position.Patients with higher postoperative arch height were selected,and their non-astigmatic eye clinical outcome were observed after ICL surgery at 1wk,1,and 3mo.The clinical measurements included uncorrected visual acuity(UCVA),intraocular pressure(IOP),refractive state,corneal endothelium cell count,and arch height.Three months later,the ICL in each patient’s non-astigmatic eye was adjusted to the vertical from the horizontal position.The results were compared before and 1wk,1,and 3mo after adjustment.RESULTS:UCVA and IOP were significantly reduced 1wk after position adjustment compared to 1wk after ICL implantation(P<0.05).The patients demonstrated significantly reduced arch height and corneal endothelium cell count 1wk,1,and 3mo after adjusting position compared to 1wk,1,and 3mo after ICL implantation(P<0.05).However,there was no significant difference in refraction between 1wk,1,and 3mo after ICL implantation and position adjustment(P>0.05).CONCLUSION:Early positioning adjustment postphakic ICL implantation can benefit patients with adjusted arch height or higher IOP.Despite the good clinical effects,the doctors should pay attention to the potential for adverse effects on UCVA and corneal endothelium cells following early position adjustment after posterior chamber phakic ICL implantation.

Bariatric surgery and diabetes:Current challenges and perspectives

Diabetes mellitus(DM)and obesity have become public issues of global concern.Bariatric surgery for the treatment of obesity combined with type 2 DM has been shown to be a safe and effective approach;however,there are limited studies that have systematically addressed the challenges of surgical treatment of obesity combined with DM.In this review,we summarize and answer the most pressing questions in the field of surgical treatment of obesity-associated DM.I believe that our insights will be of great help to clinicians in their daily practice.

Intraocular lens optic capture in pediatric cataract surgery

Posterior capsule opacification（PCO） remains the most common complication of pediatric cataract surgery despite continuous efforts to reduce its incidence. For this reason, pediatric cataract surgeons have expended considerable effort into preventing and mitigating PCO. The intraocular lens（IOL） optic capture technique has been used for the prevention of PCO after pediatric cataract surgery for more than 20 y, but there is still no professional consensus. However, recent research has shown encouraging results. The IOL optic capture technique can be performed without anterior vitrectomy to prevent PCO, even in younger children. The type and characteristics of IOLs used for optic capture technique, the location of IOL and the complications of IOL optic capture in children are here reviewed.

Clinic study on silicone hydrogel contact lenses used as bandage contact lenses after LASEK surgery

AIM: To compare the clinical performance of two types of silicon hydrogel contact lenses used as bandage lenses after LASEK surgery. METHODS: A prospective, double-masked study was conducted on 42 eyes of 21 patients who received binocular LASEK surgeries. The interocular difference in spherical equivalent power was less than -1.50D. Patients were randomly assigned to wear Galyfilcon A (Lens A) bandage contact lens in one eye and Balafilcon A (Lens B) in the fellow eye after the surgery. The responses to a subjective questionnaire on comfort of wearing, corneal epithelial status, conjunctival hyperemia, limbal neovascularization, lens fitting and contact lens debris were assessed 1 and 5 days postoperatively. Corneal endothelium was assessed before and 5 days after the surgery upon bandage lens removal. RESULTS: There was no difference between the two groups in terms of conjunctival hyperemia, limbal neovascularization, contact lens fitting, corneal epithelial status, corneal endothelium cell density (CD) and endothelium cell size (CS) at any postoperative visit. Complaints of discomfort, including foreign body sensation, pain and intolerance were statistically more among Lens B wearers at any postoperative visit (P < 0.05). Lens B appeared to attract much more debris than Lens A at the 5-day post-operative follow-up visit (P < 0.01). CONCLUSION: The two types of silicon hydrogel lenses investigated in this study demonstrated similar clinical performance in terms of corneal responses and lens fitting. However, Lens A showed a better performance in terms of comfort of wearing and deposit resistance.

High order aberration and straylight evaluation after cataract surgery with implantation of an aspheric,aberration correcting monofocal intraocular lens

·AIM: To evaluate the quality of vision in respect to high order aberrations and straylight perception after implantation of an aspheric, aberration correcting,monofocal intraocular lens(IOL).·METHODS: Twenty-one patients(34 eyes) aged 50 to83 y underwent cataract surgery with implantation of an aspheric, aberration correcting IOL(Tecnis ZCB00,Abbott Medical Optics). Three months after surgery they were examined for uncorrected(UDVA) and corrected distance visual acuity(CDVA), contrast sensitivity(CS)under photopic and mesopic conditions with and without glare source, ocular high order aberrations(HOA, Zywave II) and retinal straylight(C-Quant).· RESULTS: Postoperatively, patients achieved a postoperative CDVA of 0.0 log MAR or better in 97.1% of eyes. Mean values of high order abberations were +0.02±0.27(primary coma components) and-0.04 ±0.16(spherical aberration term). Straylight values of the C-Quant were 1.35±0.44 log which is within normal range of age matched phakic patients. The CS measurements under mesopic and photopic conditions in combination with and without glare did not show any statistical significance in the patient group observed(P ≥0.28).· CONCLUSION: The implantation of an aspherical aberration correcting monofocal IOL after cataractsurgery resulted in very low residual higher order aberration(HOA) and normal straylight.

Human lens epithelial cell apoptosis and epithelial to mesenchymal transition in femtosecond laser-assisted cataract surgery

AIM： To evaluate human lens epithelium cell apoptosis and epithelial to mesenchymal transition （EMT） induced by femtosecond laser in femtosecond laser assisted cataract surgery （FLACS）. METHODS： Sixty cataract patients with N2 to N3 stage according to the LOCS III were enrolled in this study and divided into three groups randomly： FLACSl group （cataract surgery by FLACS with LenSx）, FLACS2 group （cataract surgery by FLACS with LensAR） and manual group （cataract surgery by phacoemulsification）. Patients in two FLACS groups performed anterior capsulotomy by LenSx or LensAR laser system. Patients in the manual group were performed continuous curvilinear capsulorrhexis （CCC） manually. The anterior capsules were fixed right after moved out of eye. Hematoxylin-eosine staining, immunofluorescence staining and real-time PCR were performed in order to observe human lens epithelium cells changes after cataract surgery. RESULTS： The capsule cutting edge was shown irregularity and roughness in two FLACS groups and smooth edge in manual capsulotomy by pathologic staining. Irregularities of the cell configuration with partly swollen and destroyed nuclei were observed in two FLACS groups. Femtosecond laser could induce a significantly higher cell apoptosis in human lens epithelium cell than manually performed CCC （P〈0.05）. Lens epithelium cells apoptosis were correlated with femtosecond laser duration according to Pearson correlation analysis. Decreased N-cadherin expression, alpha-SMA and FSP-1 level in two FLACS groups showed the inhibition of cell EMT. CONCLUSION： Femtosecond laser may affect the apoptosis and EMT of lens epithelium cells which are under the peeled central lens capsule.

Optical quality of toric intraocular lens implantation in cataract surgery

AIM: To analyze the optical quality after implantation of toric intraocular lens with optical quality analysis system.METHODS: Fifty-two eyes of forty-four patients with regular corneal astigmatism of at least 1.00 D underwent implantation of Acry Sof toric intraocular lens, including T3 group 19 eyes, T4 group 18 eyes, T5 group 10 eyes,T6 group 5 eyes. Main outcomes evaluated at 3mo of follow-up, included uncorrected distance visual acuity(UDVA), corrected distance visual acuity(CDVA), residual refractive cylinder and intraocular lens(IOL) axis rotation.Objective optical quality were measured using optical quality analysis system(OQAS Ⅱ, Visiometrics, Spain),included the cutoff frequency of modulation transfer function(MTFcutoff), objective scattering index(OSI),Strehl ratio, optical quality analysis system value(OV)100%, OV 20% and OV 9% [the optical quality analysis system(OQAS) values at contrasts of 100%, 20%, and 9%].RESULTS: At 3mo postoperative, the mean UDVA and CDVA was 0.18 ±0.11 and 0.07 ±0.08 log MAR; the mean residual refractive cylinder was 0.50 ±0.29 D; the mean toric IOL axis rotation was 3.62 ±1.76 degrees, the mean MTFcutoff, OSI, Strehl ratio, OV 100%, OV 20% and OV9% were 22.862 ±5.584, 1.80 ±0.84, 0.155 ±0.038, 0.76 ±0.18,0.77±0.19 and 0.78±0.21. The values of UDVA, CDVA, IOL axis rotation, MTFcutoff, OSI, Strehl ratio, OV100%,OV20% and OV9% depending on the power of the cylinder of the implantation were not significantly different(P 】0.05), except the residual refractive cylinder(P 【0.05).CONCLUSION: The optical quality analysis system was useful for characterizing the optical quality of Acry Sof toric IOL implantation. Implantation of an Acry Sof toric IOL is an effective and safe method to correct corneal astigmatism during cataract surgery.

Ka-Band metalens antenna empowered by physics-assisted particle swarm optimization(PA-PSO)algorithm

Design of multiple-feed lens antennas requires multivariate and multi-objective optimization processes,which can be accelerated by PSO algorithms.However,the PSO algorithm often fails to achieve optimal results with limited computation resources since spaces of candidate solutions are quite large for lens antenna designs.This paper presents a design paradigm for multiple-feed lens antennas based on a physics-assisted particle swarm optimization(PA-PSO)algorithm,which guides the swarm of particles based on laws of physics.As a proof of concept,a design of compact metalens antenna is proposed,which measures unprecedented performances,such as a field of view at±55°,a 21.7 dBi gain with a flatness within 4 dB,a 3-dB bandwidth>12°,and a compact design with a f-number of 0.2.The proposed PA-PSO algorithm reaches the optimal results 6 times faster than the ordinary PSO algorithm,which endows promising applications in the multivariate and multi-objective optimization processes,including but not limited to metalens antenna designs.

Early outcomes of vision and objective visual quality analysis after cataract surgery with trifocal intraocular lens implantation

AIM: To investigate the early outcomes of vision, objective visual quality and their correlation after cataract surgery with trifocal intraocular lens implantation.METHODS: The visual examination and objective visual quality analysis using Optical Quality Analysis System(OQAS) at 1 mo and 3 mo, and defocus curve examination at 3 mo were performed in 20 patients(27 eyes) after phacoemulsification combined with trifocal intraocular lens implantation surgery.RESULTS: The uncorrected distant(UD), intermediate and near visual acuity(VA) were significantly improved after surgery(P<0.001). UDVA at 1 mo after the surgery was slightly better than that after 3 mo(P=0.026). The defocus curve after 3 mo indicated that the peak of distant vision was close to 0 logMAR, and UDVA was lower than 0.3 logMAR in the range of-1.5 D to-3.0 D. The modulation transfer function(MTF) cutoff frequency, strehl ratio(SR), Optical Quality Analysis System values(OVs), includes OV100, OV20 and OV9 after the surgery were significantly better than before surgery(P<0.001), but the objective scattering index(OSI) was significantly decreased(P<0.001). UDVA at 3 mo after the surgery had correlations with MTF cutoff, OSI, OV100 and OV20(r=-0.400, 0.431,-0.437,-0.411, P=0.039, 0.025, 0.023, 0.033). The uncorrected intermediate VA after 3 mo of the surgery had correlations with OSI and OV100(r=0.478,-0.411, P=0.012, 0.033). CONCLUSION: Trifocal intraocular lens implantation can provide good distant, intermediate and near VA, and the vision shows a well correlation with objective visual quality during early surgery.

Supercritical metalens at h-line for high-resolution direct laser writing

Supercritical lens(SCL)can break the diffraction limit in the far field and has been demonstrated for high-resolution scanning confocal imaging.Its capability in sharper focusing and needle-like long focal depth should allow high-resolution lithography at violet or ultraviolet(UV)wavelength,however,this has never been experimentally demonstrated.As a proof of concept,in this paper SCLs operating at 405 nm(h-line)wavelength with smaller full-width-at-half-maximum focal spot and longer depth of focus than conventional Fresnel zone lens while maintaining controlled side lobes are designed for direct laser writing(DLW)lithography.Aluminum nitride(AlN)with a high refractive index and low loss in UVvisible range is used to fabricate nanopillar-based metasurfaces structure for the metalens.Grating arrays with improved pitch resolution are fabricated using the SCLs with sub-diffraction-limit focusing capability.The AlN-based metasurface for SCLs at short wavelength for DLW could extend further to UV or deep UV lithography and might be of great interest to both the research and industry applications.

Intraocular lens removal or not during vitrectomy for acute infectious endophthalmitis after cataract surgery

At present, the incidence of infectious endophthalmitis after cataract surgery has been significantly reduced, but it is still a serious complication. Removal or not of the intraocular lens(IOL) during vitrectomy in cases with a moderate or severe inflammation is controversial. In order to call upon more discussion, we publish the article entitled “Timely vitrectomy without intraocular lens removal for acute endophthalmitis after cataract surgery” written by Guo et al in this issue. With recent advanced vitrectomy techniques, and critical measures for management of risk factors related to occurrence of infection, IOL remaining during timely vitrectomy for acute endophthalmitis can possibly be safe and effective in selected cases.

Evaluation of the safety and efficacy of therapeutic bandage contact lenses on post-cataract surgery patients

AIM： To evaluate the safety of therapeutic bandage contact lens for post-cataract surgery patients and to illustrate its efficacy on post-operative comfort and tear-film stability. METHODS： A total of 40 participants were recruited and randomly divided into two groups. Group one was instructed to wear bandage contact lenses for a week and use antibiotic eye drops for a month since the first day after surgery. Group two received sub-conjunctival injection of tobramycin and was asked to wear eye pads on the first day after surgery and then were instructed to use antibiotic eye drops as the first group did. Ocular surface disease index（OSDI） questionnaire, slit-lamp microscope examination of tear break-up time（TBUT）, corneal fluorescein score（CFS）, tear meniscus height（TMH） together with anterior segment optical coherence tomography（AS-OCT） and corneal topography were evaluated preoperatively and postoperatively. RESULTS： The subjective feeling（P=0.004）, TBUT（P〈0.001） and TMH（P=0.02） post-surgery had improved in patients who used bandage contact lenses compared with those who did not at 1wk post-surgery. Until three month postoperatively, the comfort degree（P=0.004） and TMH（P=0.01） of group two were still worse than group one. Moreover, TBUT（P〈0.001） and CFS（P=0.004） of the group with eye pads got worse than the results before, whereas the group with bandage contact lenses recovered to normal. None of these patients had infections or other complications. CONCLUSION： Wearing therapeutic bandage contact lens after cataract surgery, compared with traditional eye-pads, is a safe method to improve tear-film stability and reduce post-operative discomfort without hindering corneal incision recovery.

Implantable collamer lens for residual refractive error after corneal refractive surgery

AIM：To assess the safety,efficacy,predictability and stability of implantable collamer lens（ICL） for residual refractive error after corneal refractive surgery.METHODS： This study evaluated 19 eyes of 12 patients who underwent ICL implantation after corneal refractive surgeries.They were followed up for 1y to 5y of uncorrected distance visual acuity（UDVA）,corrected distance visual acuity（CDVA）,manifest refractive error,flat and steep K value,axial length,intraocular pressure,corneal endothelial cell density,adverse events after ICL surgery.RESULTS： The mean follow-up period was 39.05 ±19.22 mo（range,1-5y）.Spherical equivalent refractive error changed from-7.45±3.02 D preoperatively to-0.85±1.10 D 1wk to 1mo after ICL implantation,with the safety and efficacy indices being 1.12 and 1.15,respectively.A total of 52.63% of eyes were within ±0.5 D of the predicted spherical equivalents,73.68% were within ±1.0 D.A trend of mild regression towards myopia with axial elongation after 5y was observed.One eye with mild anterior capsule opacity and retinal detachment 1y after surgery were observed.CONCLUSION： ICL implantation is safe and effective for the correction of residual refractive error after corneal refractive surgeries,especially in moderate to high residual myopia.

Dynamic profile of ocular refraction in pediatric cataract patients after lens surgeries

AIM: To study the change in ocular refraction in patients with pediatric cataracts(PCs) after lens extraction. METHODS: A total of 1258 patients who were undergoing cataract extraction with/without intraocular lens(IOL)implantation were recruited during preoperative examinations between Jan 2010 and Oct 2013. Patient ages ranged from 1.5 mo to 14y. Follow-ups were conducted at1 wk, 1, and 3 mo postoperatively and every 3 mo in the first year, then 6 mo thereafter. Ocular refraction [evaluated as spherical equivalent(SE)] and yearly myopic shift(YMS)were recorded and statistically analyzed among patients with age at surgery, baseline ocular refraction, gender,postoperative time and laterality(bilateral vs unilateral). RESULTS: By Dec 31st 2015, 1172 participants had been followed for more than 2y. The median follow-up period was 3y. The critical factors affecting the ocular refraction of PC patients were baseline ocular refraction, postoperative time for both aphakic and pseudophakic eyes. YMS grew most rapidly in young childhood and early adolescence. CONCLUSION: After lens surgeries, ocular refraction in PC patients shows an individual difference of change.Further concerns should be raising to monitor the rapid myopic shift at early adolescence of these patients.

Sutured scleral fixation of existing subluxated/dislocated acrylic one-piece intraocular lenses

AIM:To evaluate the visual and refractive outcomes in cases after sutured scleral fixation of existing subluxated or dislocated acrylic one-piece intraocular lenses(IOLs).METHODS:This study retrospectively enrolled a consecutive series of patients who underwent a surgery of sutured existing subluxated or dislocated IOLs from October 2018 to June 2020.All patients underwent comprehensive preoperative and postoperative ophthalmologic examination,and data were collected including age,sex,surgical indications,best-corrected visual acuity,refractive error,intraocular pressure.Presence of intraoperative and postoperative surgical complications was documented.RESULTS:A total of 20 consecutive cases were enrolled for analysis with mean final follow-up period 9.8±5.3mo.Visual acuity improved from a mean of 0.35(0.46±0.32 logMAR)preoperatively to 0.61(0.21±0.18 logMAR)at the 3-month follow-up(P=0.002).The mean amount of preoperative keratometric astigmatism and total postoperative refractive astigmatism was-1.24±0.80 diopters(D)and-1.42±0.97 D,respectively.There was no statistically significant difference between preoperative and postoperative astigmatism(P=0.156).The mean IOL-induced astigmatism was-0.23±0.53 D.The mean spherical equivalent at the 3-month follow-up was-0.1±0.94 D.No major complications were noted during the follow-up period.CONCLUSION:Surgical techniques using sutured scleral fixation of existing subluxated or dislocated acrylic one-piece IOLs result in favorable visual and refractive outcomes without major complications.

Effect of femtosecond laser-assisted lens surgery on the optic nerve head and the macula

AIM: To evaluate the effect of femtosecond laser-assisted lens surgery(FLALS;cataract surgery or refractive lens exchange) on the structure of the optic nerve head and the macula.METHODS: This prospective longitudinal study included healthy eyes undergoing FLALS. Eyes with glaucoma or any other ocular disease that could alter optical coherence tomography results were excluded. Retinal nerve fiber layer(RNFL), Bruch’s membrane opening-minimum rim width(BMO-MRW) and macular thickness(MT) were measured preoperatively, 1 and 6 mo after surgery using spectral-domain optical coherence tomography(SD-OCT). Changes between preoperative and postoperative values were evaluated.RESULTS: A total of 87 eyes of 46 patients were included in this study. Preoperative RNFL, BMO-MRW and MT in microns(μm) were 100.77±10.39, 330.31±49.99 and 276.30±33.39, respectively. Postoperative RNFL, BMO-MRW and MT were 104.74±11.55, 348.32±54.05 and 279.83±22.65 1 mo after surgery and 102.93±11.17, 343.11±53.4 and 278.90±22.19 6 mo after surgery, respectively;which equals an increase of 3.93%, 5.45% and 1.27%,respectively, 1 mo after surgery, and 2.14%, 3.87% and 0.94% 6 mo after surgery. The differences between the preoperative and the postoperative RNFL and BMO-MRW values were statistically significant(P<0.001). Regarding MT values, there were not statistically significant differences(P=0.26).CONCLUSION: Our study suggests that FLALS does not have a negative impact on the structural status of the optic nerve head in healthy eyes, assessed by SD-OCT. There is a slight increase in the values of RNFL, BMO-MRW and MT 1 mo and 6 mo after surgery.

Image-guided lens extraction surgery: a systematic review

A systematic review of the recent literature regarding the current image-guided systems used for cataract surgery or refractive lens exchange was performed based on the PubMed and Google Scholar databases in March 2018. Literature review returned 21 eligible studies. These studies compared image-guided systems with other keratometric devices regarding their accuracy, repeatability and reproducibility in measurement of keratometric values, astigmatism magnitude and axis, as well as in IOL power calculation. Additionally, the image-guided systems were compared with conventional manual ink-marking techniques for the alignment of toric IOLs. In conclusion, image-guided systems seem to be an accurate and reliable technology with measurements of high repeatability and reproducibility regarding the keratometry and IOL power calculation, but not yet interchangeable with the current established and validated keratometric devices. However, they are superior over the conventional manual inkmarking techniques for toric IOL alignment.

Using Topical Anesthesia for Standing Phacoemulsification Cataract Surgery and Intraocular Lens Implantation

Introduction: To report by using topical anesthesia for standing phacoemulsification and intraocular lens implantation for two patients who need cataract extraction but unable to lie flat with marked cervical kyphosis due to long-standing ankylosing spondylitis and chronic uveitis. Methods: Two patients are unable to lie flat respectively during phacoemulsification underwent this technique in Jingdong and Tonghai county Hospital of Yunnan province in China. Each patient was positioned erect or semirecumbent in a standard reclining cataract surgical chair. The ceiling-mounted microscope was rotated 60 degrees from the vertical to point toward the patient. Results: The intraoperative and postoperative periods were uneventful in two patients, with good visual outcomes after surgery. Conclusion: This technique is valuable for situations where the patient requires upright positioning because of the inability to recline flat, and should be considered for cases where standard surgical positioning is not possible.

Evaluating the Effects of Graviton Redshift upon Spiral Galaxy Rotation Curves, Surface Brightness Magnitudes and Gravitational Lensing

The effects of the gravitational redshift of gravitons upon spiral galaxy rotation energy are compared to the standard mass to light analyses in obtaining rotation curves. The derivation of the total baryonic matter compares well with the standard theory and the rotation velocity is matched to a high precision. The stellar mass distributions obtained from the fit with graviton energy loss are used to derive the surface brightness magnitudes for the galaxies, which agree well with the observed measurements. In a new field of investigation, the graviton theory is applied to the observations of gravitational lenses. The results of these applications of the theory suggest that it can augment the standard methods and may eliminate the need for dark matter.