Modeling monocular form deprivation in rabbits using a simulated-cataract intraocular lens

AIM:To establish an animal model of form deprivation amblyopia based on a simulated cataract intraocular lens(IOLs).METHODS:Poly(dimethyl siloxane)-SiO_(2) thin films(PSF)with different degrees of opacity as IOL materials were prepared.The light transmission of the PSF-IOL was measured,and its in vitro biosafety was determined by cell counting kit(CCK)-8 assay using the HLEC-B3 cell line and ARPE-19 cell line.Subsequently,the in vivo safety was determined by implanting the PSF-IOL with 10%wt SiO_(2) into the right eyes of New Zealand white rabbits(PSF-IOL group),and compared with two control groups:contralateral comparison group and normal control(NC)group(Contralateral comparison group:the fellow eye;NC group:a group of binocular normal rabbits without intervention).The flash visual-evoked potentials(F-VEPs)were measured to verify amblyopia.RESULTS:PSFs containing 0,2%,and 10%wt SiO_(2) were successfully constructed.The 0 SiO_(2) PSF was transparent,while the 10%wt SiO_(2) PSF was completely opaque.It was found that PSF did not induce unwanted cytotoxicity in HLECs and ARPE19 cells in vitro.In vitro,PSF-IOL with 10%wt SiO_(2) was also non-toxic,and no significant inflammation or structural changes occurred after four weeks of PSF-IOL implantation.Finally,our IOL-simulated congenital cataract rabbit detected by F-VEPs suggested tentative amblyopia.CONCLUSION:A PSF-IOL that mimics cataracts is created.A novel form deprivation model is created by the IOL-simulated congenital cataract rabbit.It can be developed fast and stable and holds great potential for future study.

Transcapsular scleral fixation of the standard capsular tension ring and in-the-bag intraocular lens implantation for severely subluxated lenses

AIM:To present a technique of transcapsular scleral fixation of the standard capsular tension ring(CTR)through equatorial capsulotomy and in-the-bag intraocular lens(IOL)implantation in subluxated lenses.METHODS:This retrospective consecutive case series included patients with subluxated lenses by more than 180 degrees who underwent lens extraction,transcapsular scleral fixation of the standard CTR through equatorial capsulotomy,in-the-bag IOL implantation and with at least 6mo follow-up.Preoperative and postoperative best corrected visual acuity(BCVA),intraocular pressure(IOP),complications,and postoperative IOL tilt and decentration were recorded.RESULTS:Nine eyes of 7 patients with a mean followup of 11.0±3.7mo were included in this study.The BCVA was significantly improved from 0.64±0.22 logMAR preoperatively to 0.21±0.19 logMAR postoperatively(P<0.001).The IOP was within the normal range postoperatively.The mean tilt of the IOL was 4.30°±2.31°(range,1.0°to 8.9°)and the mean decentration of the IOL was 0.37±0.12 mm(range,0.14 to 0.50 mm).No visually threatened intraoperative and postoperative complications were detected during the follow-up period.CONCLUSION:This is a safe and effective surgical technique for managing patients with severely subluxated lenses.It has achieved favorable outcomes with fewer surgical manipulations and less need for advanced capsular support devices.

Clinical usefulness of the baby vision test in young children and its correlation with the Snellen chart

AIM:To investigate the efficacy of a new visual acuity(VA)screening method,the baby vision test for young children.METHODS:A total 105 eyes of 65 children aged 2-8y were included in the study.Acuity testing was conducted using a standardized recognition acuity chart(Snellen visual chart:at 3 m)and the baby vision model assessment.The baby vision device includes a screen,a near infrared camera and a computer.Children were seated at a measured distance of 33-40 cm from a display for testing.VA was estimated according to the highest resolution the children could follow.Decimal VA data were converted to logarithm of the minimum angle of resolution(logMAR)for statistical analysis.The VA results for each child were recorded and analyzed for consistency.RESULTS:The mean VA measured using the Snellen visual chart was 0.62±0.32,and that assessed using the baby vision test was 0.66±0.27.The 95%limit of agreement was-0.609 to 0.695,with 95.2%(100/105)plots within the 95%limits of agreement.VA values of the baby vision test were significantly correlated with those of the Snellen chart(R=0.274,P=0.005).CONCLUSION:The baby vision test can be used as a relatively reliable method for estimating VA in young children.This new acuity assessment might be a valid predictor of optotype-measured acuity later in preverbal children.

Evaluation of optic nerve head vessels density changes after phacoemulsification cataract surgery using optical coherence tomography angiography

·AIM:To evaluate optic nerve head(ONH)vessel density(VD)changes after cataract surgery using optical coherence tomography angiography(OCTA).·METHODS:This was a prospective observational study.Thirty-four eyes with mild/moderate cataracts were included.ONH scans were obtained before and 3mo after cataract surgery using OCTA.Radial peripapillary capillary(RPC)density,all VD,large VD and retinal nerve fiber layer thickness(RNFLT)in total disc,inside disc,and different peripapillary sectors were assessed and analyzed.Image quality score(QS),fundus photography grading and bestcorrected visual acuity(BCVA)were also collected,and correlation analyses were performed between VD change and these parameters.·RESULTS:Compared with baseline,both RPC and all VD increased in inside disc area 3mo postoperatively(from 47.5%±5.3%to 50.2%±3.7%,and from 57.87%±4.30%to 60.47%±3.10%,all P<0.001),but no differences were observed in peripapillary area.However,large VD increased from 5.63%±0.77%to 6.47%±0.72%in peripapillary ONH region(P<0.001).RPC decreased in inferior and superior peripapillary ONH parts(P=0.019,<0.001 respectively).There were obvious negative correlations between RPC change and large VD change in inside disc,superior-hemi,and inferior-hemi(r=-0.419,-0.370,and-0.439,P=0.017,0.044,and 0.015,respectively).No correlations were found between VD change and other parameters including QS change,fundus photography grading,postoperative BCVA,and postoperative peripapillary RNFLT.·CONCLUSION:RPC density and all VD in the inside disc ONH region increase 3mo after surgery in patients with mild to moderate cataract.No obvious VD changes are found in peripapillary area postoperatively.

Contrast visual acuity after multifocal intraocular lens implantation: aspheric versus spherical design

AIM: To evaluate contrast visual acuity(CVA) after implantation of an aspheric apodized diffractive intraocular lens(IOL) or a spherical apodized diffractive IOL in cataract surgery. ·METHODS: This prospective randomized controlled study with a 12-month follow-up compared the results of cataract surgery with implantation of an aspheric AcrySof ReSTOR SN6AD3 IOL(30 eyes) and a spherical AcrySof ReSTOR SN60D3 IOL(30 eyes). CVA with best distance correction was measured at 4 contrast levels(100%,25%,10% and 5%) under 3 levels of chart luminance [250,85 and 25 candelas per square meter(cd/m2)] using a multi-functional visual acuity tester(MFVA-100). ·RESULTS: At 12 months after surgery,there were no statistically significant differences in 100% CVA and 25% CVA under 250cd/m2(P100% =0.875 and P25% =0.057) and 85cd/m2(P100% =0.198 and P25% =0.193) between the aspheric group and the spherical group. However,the 10% CVA and 5% CVA were significant better in aspheric group than spherical group under 250cd/m2(P10% =0.042 and P5% = 0.007) and 85cd/m2(P10% =0.002 and P5%=0.039). Under the luminance level of 25cd/m 2,no significant differences was found in the 100% CVA between the 2 group(P100% = 0.245),while aspheric group had better visual acuity in the remaining 3 contracts(P25% =0.023,P10% =0.026 and P5% = 0.002,respectively). ·CONCULSION: The aspheric AcrySof ReSTOR SN6AD3 IOL provided patients with better low-contrast visual acuity than the spherical AcrySof ReSTOR SN60D3 IOL.

Effect of simulated dynamic intraocular pressure on retinal thickness measured by optical coherence tomography after cataract surgery

AIM: To investigate the effect of simulated dynamic intraocular pressure (SDIOP) during uncomplicated phacoemulsification on postoperative macular and peripapillary retinal nerve fiber layer (RNFL) thickness. METHODS: Macular and RNFL thicknesses in one eye of patients (n=30) undergoing uncomplicated phacoemulsification were measured by optical coherence tomography preoperatively and 1 week postoperatively. The best-corrected visual acuity, SDIOP, irrigation time (IT), effective phacoemulsification lime, entire surgical duration, blood pressure, and heart rate were recorded. RESULTS: The mean SDIOP and IT was (74.9 +/- 27.4)cmH(2)O and (178.4 +/- 21.6) seconds respectively. We divided our patients into two groups based upon IT with greater than 90cmH(2)O (P>90IT). In Group A (n= 14), the P>90IT was greater than the mean P>90IT, and in Group B (n=16), the P>90IT was less than the mean P>90IT. For all patients there was a significant increase in macular thickness one week after cataract surgery (P=0.001). While the RNFL thickness tended to increase, the change was not significant. The postoperative macular thickness of Group A,(277.8 +/- 13.7)mu m, was significantly thicker than that of Group B, (267.9 +/- 15.0)mu m (P=0.004). The postoperative peripapillary RNFL thickness of Group A, (96.8 +/- 10.8)mu m, was not significantly different from Group B. For Group A, the change in macular thickness was positively correlated with P>90IT (R-2=0.524, P =0.02). There was no statistical difference in postoperative visual acuity between Groups A and B. CONCLUSION: After uncomplicated phacoemulsification, increased macular thickness is associated with the IT under high SDIOP. The effect of high SDIOP is limited to the sub-clinical level.

Assessment of anterior chamber angle changes after phacoemulsification with swept-source OCT

AIM:To assess the changes of anterior chamber angle in patients with shallow anterior chamber after phacoemulsification combined with intraocular lens(IOL)implantation,based on anterior segment swept-source optical coherence tomography(AS-SS-OCT)measurements.METHODS:This was a prospective case control study;sixty eyes of sixty case were scheduled for cataract surgery with normal intraocular pressure(IOP).Based on anterior chamber depth(ACD)and gonioscopy findings,the eyes were divided into two groups:group of shallow anterior chamber and narrow angle(SAC group,30 eyes);and group of normal anterior chamber group with wide angle(NAC group,30 eyes).Measurements of ACD,anterior chamber volume(ACV),iris volume(IV),lens vault(LV),angle opening distance(AOD),angle recess area(ARA),trabecular iris space area(TISA),and trabecular iris angle(TIA)were conducted in each group before and 3mo after surgery.RESULTS:There was no significant difference in age,axial length(AL),corneal curvature,corneal diameter,intraocular pressure,and IV between two groups before surgery,except for the LV(P=0.000).ACD and ACV were prominently larger in the NAC group than the SAC group 3mo after operation(3.69±0.38 vs 3.85±0.39 mm,P=0.025;161.37±19.47 vs 178.26±20.30 mm3,P=0.002).AOD750,ARA750 in nasal and inferior quadrants,TISA750 in all quadrants except temporal,and TIA750 in all quadrants in SAC group were significantly smaller than those in NAC group after operation(all P<0.05).CONCLUSION:Cataract surgery can deepen anterior chamber and increase the width of anterior chamber angle in Chinese subjects,but the angle related parameters including AOD750,ARA750,TISA750,TIA,TISA750,and ACV in patients with shallow anterior chamber and narrow angle do not reach the normal level.

Retinal vessel diameter changes induced by transient high perfusion pressure

·AIM: To investigate the effects of transient high perfusion pressure on the retinal vessel diameter and retinal ganglion cells.·METHODS: The animals were divided into four groups according to different infusion pressure and infusion time(60 mm Hg-3min, 60 mm Hg-5min, 100 mm Hg-3min, 100 mm Hg-5min). Each group consisted of six rabbits. The left eye was used as the experimental eye and the right as a control. Retinal vascular diameters were evaluated before, during infusion, immediately after infusion, 5min, 10 min and 30 min after infusion based on the fundus photographs. Blood pressure was monitored during infusion. The eyes were removed after 24 h.Damage to retinal ganglion cell(RGC) was analyzed by histology.·RESULTS: Retina became whiten and papilla optic was pale during perfusion. Measurements showed significant decrease in retinal artery and vein diameter during perfusion in all of the four groups at the proximal of the edge of the optic disc. The changes were significant in the 100 mm Hg-3min group and 100 mm Hg-5min group compared with 60 mm Hg-3min group(P 1=0.025, P 2=0.000).The diameters in all the groups recovered completely after 30 min of reperfusion. The number of RGC)showed no significant changes at the IOP in 100 mm Hg with5 min compared with contralateral untreated eye(P 】0.05).·CONCLUSION: Transient fluctuations during infusion lead to temporal changes of retinal vessels, which could affect the retinal blood circulation. The RGCs were not affected by this transient fluctuation. Further studies are necessary to evaluate the effect of pressure during realtime phacoemusification on retinal blood circulation.

Commentary review:challenges of intraocular lens implantation for congenital cataract infants

As an indispensable part of congenital cataract surgery,intraocular lens(IOL)implantation in infantile patients has long-term positive impacts on visual rehabilitation,as well as postoperative complications inevitably.Timing of IOL implantation in infantile congenital cataract patients is not simply a point-in-time but a personalized decision that comprehensively takes age at surgery,risks of postoperative complications,and economic condition of family in consideration,and combines with choosing suitable IOL type and power.For infants with well-developed eyeballs and good systemic conditions,IOL implantation at six months of age or older is safe and effective.Otherwise,secondary IOL implantation may be a safer choice.

Morphological changes in the iridocorneal angle and their relationship with intraocular pressure after infantile cataract surgery

·AIM:To evaluate morphological changes in the iridocorneal angle after pediatric cataract surgery.·METHODS:Children who underwent primary infantile cataract surgery were included and 64 eyes from 41 children,including 18 with unilateral cataracts(18 eyes)and 23 with bilateral cataracts(46 eyes)were examined.All patients underwent two gonioscopic examinations to evaluate the iridocorneal angle,before the primary lens removal and before the secondary intraocular lens implantation.The anatomical changes in the iridocorneal angle and the relationship between intraocular pressure(IOP)and iridocorneal angle changes were also analyzed.·RESULTS:The iridocorneal angle was wide in 64 eyes before and after surgery.The trabecular meshwork pigmentation,number of iris processes in every quadrant of the iridocorneal angle,and the width of the ciliary body band in the superior and inferior quadrants at the second gonioscopic examination were significantly increased compared to those at the first examination(P<0.001,P<0.05,P<0.05.and P<0.05,respectively).IOP gradually increased at 1 mo after operation,and returned to the preoperative level at 3 mo.However,IOP still increased significantly at 6 and 12 mo.·CONCLUSION:The main changes after pediatric cataract surgery include an increase in trabecular meshwork pigmentation and number of iris processes,IOP gradually increase and has positive correlation with trabecular meshwork pigmentation and anterior insertion of iris process.

Progressive cracking technique for phacoemulsification of superhard cataracts: a case report

Background:Complete nuclear disassembly of superhard cataracts cannot always be achieved by phaco chop,which is considered one of the best techniques for dealing with hard cataracts.We present a phaco chopprogressive cracking technique to divide superhard cataracts completely.Case presentation:We presented a case of cataract with over Grade V nucleus sclerosis and very low density of corneal endothelial cell(812 cells/mm^(2)).By performing the cataract surgery with our phaco chop-progressive cracking technique,the corneal endothelial cells were well protected and the patient’s visual acuity was markedly improved from finger counting at 40 cm to 20/200 the day after surgery without obvious corneal edema.Conclusions:Although an initial learning curve was needed,this phaco chop-progressive cracking technique could be of particular benefit to the superhard cataract,especially in patients with low density of corneal endothelial cells.