Topography versus non-topography-guided photorefractive keratectomy with corneal cross-linking variations in keratoconus

AIM:To compare the visual results of non-topographyguided and topography-guided photorefractive keratectomy(PRK)applying sequential and simultaneous corneal crosslinking(CXL)treatment for keratoconus.METHODS:Interventional and comparative prospective study.Sixty-nine eyes(36 patients)suffering from keratoconus(stages 1 Amsler-Krumeich classification)were divided into four groups:sequential topography-guided photorefractive keratectomy with CXL,simultaneous topography-guided photorefractive keratectomy with CXL,simultaneous nontopography guided photorefractive keratectomy with CXL,and sequential non-topography guided photorefractive keratectomy with CXL.The main outcome measures were pre-and postoperative uncorrected distance visual acuity(UDVA),best corrected distance visual acuity(CDVA),manifest refraction,contrast sensitivity,and keratometry.RESULTS:All analyzed visual,contrast sensitivity,and refractive parameters showed a significant improvement in the four groups(all P<0.05).A noticeable improvement was seen in keratometry in all the groups,and a remarkable difference was observed between topography-guided groups in comparison to non-topography-guided groups(P<0.05).Interestingly,the improvement in all parameters showed a degree of stability to the end of the follow-up.CONCLUSION:The treatment priorities in all four groups are safety,efficacy,and predictability in the correction of the sphero-cylindrical errors in mild and moderate keratoconus.No significant differences among groups in the recorded objective outcomes were found.

Patients’dissatisfaction with multifocal intraocular lenses managed by exchange with other multifocal lenses of diferent optical profles

Background:The aim of the study was to evaluate the outcomes of dissatisfed patients reporting poor visual quality following implantation of multifocal intraocular lenses(MF-IOLs),managed by IOL exchange with another multifocal optical profle.Methods:This is a retrospective series of cases.MF-IOL exchange was done in 15 dissatisfed patients(30 eyes)with the perception of poor visual quality for far distance afected by neuroadaptation failure.Patients underwent a bilateral exchange of a MF-IOL with another MF-IOL of a diferent optical profle.Visual outcomes and complications were analyzed.Questionnaires including Quality of Vision(QoV),Visual Function Index-14(VF-14)and its Rasch-revised version(VF-8R)and a satisfaction questionnaire were also used for outcome evaluation.Results:The mean elapsed time from implantation to explantation-reimplantation was 11.8 months.The QoV scores improved signifcantly across all the three subscales.Visual function improved with a change in VF-14 score from 60.41±24.81 to 90.16±10.91(P<0.001).The VF-8R score improved as well.The uncorrected distance visual acuity improved from 0.24 to 0.12 logMAR after exchange(P<0.001)and corrected distance visual acuity improved from 0.15 to 0.04 logMAR(P<0.001).Safety and efcacy indexes reached 1.46 and 1.16,respectively.Concerning patients’satisfaction following MF-IOL exchange,80%of the patients reported they would have the MF-IOL reimplantation procedure again.Conclusions:Patient dissatisfaction with neuroadaptation failure following MF-IOL implantation can be managed in 80%of our cases by MF-IOL exchange with a diferent MF-IOL optical profle.

Corneal collagen cross-linking epithelium-on vs. epithelium-off: a systematic review and meta-analysis

Background The purpose of the study was to determine the advantages and disadvantages of epi-on corneal cross-linking(CXL)techniques compared with standard epi-off CXL.Methods We searched MEDLINE and EMBASE for randomized controlled trials(RCTs)and non-randomized studies of interventions(NRSIs)and we evaluated the selected papers according to the Cochrane risk of bias tool.We considered,as primary outcomes,average Kmax flattening,changes in uncorrected and corrected distance visual acuity(UDVA and CDVA);as secondary outcomes,we considered changes in pachymetry values and endothelial cell density(ECD).We also investigated adverse events related to the treatments and treatment failure.Meta-analysis was conducted with a fixed or random-effects model using weighted mean difference(MD)with 95%confidence interval(CI)as the effect size.Results A total of 15 studies were included and among these 15 trials,9 were RCTs and 6 were NRSIs,but only 4 studies showed no high risk of bias and were included in this meta-analysis.Our analysis revealed significant postoperative differences in CDVA(MD=0.07;95%CI 0.04 to 0.10;P<0.001),and no significative differences in UDVA,Kmax,central corneal thickness(CCT)and ECD(P>0.05).Epi-on CXL protocol was found to be significantly less prompt to have risks of delay in epithelial healing(P=0.035)and persistent stromal haze(P=0.026).Conclusion Epi-on CXL is as effective as epi-off CXL.Except for a higher significant improvement in CDVA with current epi-on protocols,our meta-analysis demonstrates that epi-on and epi-off CXL have comparable effects on visual,topographic,pachymetric,and endothelial parameters.Epi-on CXL has clinical advantages in terms of comfort and avoidance of complications as it reduces the risk of developing delay in epithelial healing and persistent stromal haze.

Retinal image quality with multifocal, EDoF, and accommodative intraocular lenses as studied by pyramidal aberrometry

BackgroundTo study and compare the clinical optical image quality following implantation with different premium IOLs by analysing the point spread function (PSF) Strehl ratio using a pyramidal wavefront sensor (PWS)-based aberrometer.MethodsThis study included 194 eyes implanted with: (a) 19 AcrySof SA60AT (control group);(b) 19 Miniwell;(c) 24 LENTIS Mplus LS-313 MF30;(d) 33 LENTIS Mplus LS-313 MF15;(e) 17 AkkoLens Lumina;(f) 31 AT LISA Tri 839MP;(g) 20 Precizon Presbyopic;(h) 20 AcrySof IQ PanOptix;(i) 11 Tecnis Eyhance. Main outcome measures were PSF Strehl ratio, PSF Strehl ratio excluding second-order aberrations (PSFw2), total root mean square (RMS), low-order aberration (LOA) and high-order aberration (HOA) RMS measured by PWS aberrometer.ResultsAT LISA Tri had the highest PSFw2 Strehl ratio at both 3.0- and 4.0-mm pupil size (0.52 ± 0.14 and 0.31 ± 0.10;P < 0.05), followed by SA60AT (0.41 ± 0.11 and 0.28 ± 0.07) and PanOptix (0.4 ± 0.07 and 0.26 ± 0.04). AT LISA Tri was found to provide a significantly better retinal image quality than PanOptix at both 3.0 mm (P < 0.0001) and 4.0 mm (P = 0.004). Mplus MF15 was found to be significantly better than Mplus MF30 at both 3.0 mm (P < 0.0001) and 4.0 mm (P = 0.002). Total RMS, LOA RMS, HOA RMS, PSF Strehl ratio and PSFw2 varied significantly between the studied groups (P < 0.001).ConclusionsFar distance clinical image quality parameters measured by PWS aberrometer differed significantly according to the technology of the implanted lens. AT LISA Tri, SA60AT and PanOptix showed the highest values of far distance retinal image quality, while the lowest PSFw2 Strehl ratios were displayed by Miniwell, Mplus MF30 and Precizon Presbyopic.

Corneal surgery in keratoconus: which type, which technique, which outcomes?

Keratoconus is a disease characterized by progressive thinning,bulging,and distortion of the cornea.Advanced cases usually present with loss of vision due to high irregular astigmatism.A majority of these cases require surgical intervention.This review provides an update on the current treatment modalities of corneal surgery available for the management of advanced corneal ectasias.

The use of intracorneal ring segments in keratoconus

Keratoconus is a corneal degeneration that usually appears during puberty and may seriously deteriorate the quality of life of the patients.This corneal disease is today the first indication of corneal transplantation in young patients.Until the last decade of the XX century,keratoplasty procedures were the only alternative to treat this pathological condition.In the beginning of the XXI century,intracorneal ring segments implantation was proposed as a therapeutic choice for treating keratoconus patients.Since then,several published articles have reported the benefits of this surgical procedure in treating this type of corneal ectatic disorder.The purpose of the present investigative work is to summarize the characteristic of the intracorneal ring segments and also to review the different features published in the literature in relation to this surgical technique for the treatment of keratoconus patients.

Retinal image quality with multifocal,EDoF,and accommodative intraocular lenses as studied by pyramidal aberrometry

Background:To study and compare the clinical optical image quality following implantation with different premium IOLs by analysing the point spread function(PSF)Strehl ratio using a pyramidal wavefront sensor(PWS)-based aberrometer.Methods:This study included 194 eyes implanted with:(a)19 AcrySof SA60AT(control group);(b)19 Miniwell;(c)24 LENTIS Mplus LS-313 MF30;(d)33 LENTIS Mplus LS-313 MF15;(e)17 AkkoLens Lumina;(f)31 AT LISA Tri 839MP;(g)20 Precizon Presbyopic;(h)20 AcrySof IQ PanOptix;(i)11 Tecnis Eyhance.Main outcome measures were PSF Strehl ratio,PSF Strehl ratio excluding second-order aberrations(PSFw2),total root mean square(RMS),low-order aberration(LOA)and high-order aberration(HOA)RMS measured by PWS aberrometer.Results:AT LISA Tri had the highest PSFw2 Strehl ratio at both 3.0-and 4.0-mm pupil size(0.52±0.14 and 0.31±0.10;P<0.05),followed by SA60AT(0.41±0.11 and 0.28±0.07)and PanOptix(0.4±0.07 and 0.26±0.04).AT LISA Tri was found to provide a significantly better retinal image quality than PanOptix at both 3.0 mm(P<0.0001)and 4.0 mm(P=0.004).Mplus MF15 was found to be significantly better than Mplus MF30 at both 3.0 mm(P<0.0001)and 4.0 mm(P=0.002).Total RMS,LOA RMS,HOA RMS,PSF Strehl ratio and PSFw2 varied significantly between the studied groups(P<0.001).Conclusions:Far distance clinical image quality parameters measured by PWS aberrometer differed significantly according to the technology of the implanted lens.AT LISA Tri,SA60AT and PanOptix showed the highest values of far distance retinal image quality,while the lowest PSFw2 Strehl ratios were displayed by Miniwell,Mplus MF30 and Precizon Presbyopic.

Corneal collagen cross‑linking epithelium‑on vs.epithelium‑off:a systematic review and meta‑analysis

Background:The purpose of the study was to determine the advantages and disadvantages of epi-on corneal crosslinking(CXL)techniques compared with standard epi-off CXL.Methods:We searched MEDLINE and EMBASE for randomized controlled trials(RCTs)and non-randomized studies of interventions(NRSIs)and we evaluated the selected papers according to the Cochrane risk of bias tool.We considered,as primary outcomes,average Kmax flattening,changes in uncorrected and corrected distance visual acuity(UDVA and CDVA);as secondary outcomes,we considered changes in pachymetry values and endothelial cell density(ECD).We also investigated adverse events related to the treatments and treatment failure.Meta-analysis was conducted with a fixed or random-effects model using weighted mean difference(MD)with 95%confidence interval(CI)as the effect size.Results:A total of 15 studies were included and among these 15 trials,9 were RCTs and 6 were NRSIs,but only 4 studies showed no high risk of bias and were included in this meta-analysis.Our analysis revealed significant postoperative differences in CDVA(MD=0.07;95%CI 0.04 to 0.10;P<0.001),and no significative differences in UDVA,Kmax,central corneal thickness(CCT)and ECD(P>0.05).Epi-on CXL protocol was found to be significantly less prompt to have risks of delay in epithelial healing(P=0.035)and persistent stromal haze(P=0.026).Conclusion:Epi-on CXL is as effective as epi-off CXL.Except for a higher significant improvement in CDVA with current epi-on protocols,our meta-analysis demonstrates that epi-on and epi-off CXL have comparable effects on visual,topographic,pachymetric,and endothelial parameters.Epi-on CXL has clinical advantages in terms of comfort and avoidance of complications as it reduces the risk of developing delay in epithelial healing and persistent stromal haze.

Artificial neural network to guide intracorneal ring segments implantation for keratoconus treatment:a pilot study

Background:To analyze the clinical results of an artificial neural network(ANN)that has been processed in order to improve the predictability of intracorneal ring segments(ICRS)implantation in keratoconus.Methods:This retrospective,comparative,nonrandomized,pilot,clinical study included a cohort of 20 keratoconic eyes implanted with intracorneal ring segments KeraRing(Mediphacos,Belo Horizonte,Brazil)using the ANN(ANN group)and 20 keratoconic eyes implanted with KeraRing using the manufacturer’s nomograms(nomogram group).Uncorrected distance visual acuity(UDVA),corrected distance visual acuity(CDVA)(visual acuity is expressed in decimal value and in LogMAR value in brackets),manifest refraction,corneal topography,tomography,aberrometry,pachymetry and volume analysis(Sirius System.CSO,Firenze,Italy)were performed during the preoperative visit;and the two groups,ANN group and nomogram group,did not differ significantly preoperatively in all of the parameters evaluated.These preoperative values were compared with the results obtained at the third-month visit.Mann-Whitney test and Wilcoxon test were used for the statistical analyses.Results:The spherical equivalent and the keratometric values decreased significantly in both groups.The CDVA improved from 0.60±0.23(0.22 LogMAR)pre-operatively to 0.73±0.21(0.14 LogMAR)post-operatively in the ANN group(p<0.005),and from 0.54±0.19(0.27 LogMAR)pre-operatively to 0.62±0.19(0.21 LogMAR)post-operatively in the nomogram group(p<0.01),with statistically significant difference between the two groups(p<0.05),being better in the ANN group.Coma-like aberrations decreased significantly in the ANN group,while in the nomogram group they did not change significantly,but no statistically significant difference was found between the two groups.Conclusions:ANN to guide ICRS provides an increase in the visual acuity,reduction in the spherical equivalent and improvement in the optical quality of keratoconus patients.ANN gives better results when compared with the manufacturer’s nomograms in terms of better corrected vision and reduction of the coma-like aberrations.The constant inclusion of new cases will make the predictability of ANN increasingly better as the software finetunes its learning.

Safety and visual outcomes following posterior chamber phakic intraocular lens bilensectomy

Background:To evaluate the safety,efficacy,refractive outcomes and causes for bilensectomy[phakic intraocular lens(plOL)explantation with cataract surgery and pseudophakic intraocular lens(IOL)implantation]in patients previously implanted with posterior chamber plOLs(PC plOLs).Methods:This multi-center retrospective study included 87 eyes of 55 patients who underwent bilensectomy for PC plOL with a follow-up time of 12 months.The uncorrected and corrected distance visual acuities(UDVA,CDVA),endothelial cell density before and after bilensectomy were assessed,as well as the cause of bilensectomy and intra or postoperative complications.Results:There was a statistically significant improvement in UDVA and CDVA after bilensectomy(P=0.00).The main reason for bilensectomy was cataract development(93.1%of the cases),followed by miscalculation of lens size,and corneal edema.The endothelial cell count remained stable without a statistically significant change after surgery(P=0.67).The refractive efficacy index was 0.8,none of the patients lost lines of CDVA after surgery,73%of the patients were within±1.0D(spherical equivalent)of the target refraction.Intraoperative complications were one posterior capsule rupture with the IOL implanted in the sulcus,and three eyes required the use of pupil expanders for adequate pupil dilation.Postoperatively,one eye developed retinal detachment.The three plOLs models explanted were the implantable collamer lens(ICL);implantable phakic contact lens(IPCL)and the phakic refractive lens(PRL).Conclusions:Good safety and visual outcomes were observed one year after bilensectomy for PC plOLs.There were few intra and postoperative complications and there was no significant endothelial cell loss after the bilensectomy procedure.

Artificial neural network to guide intracorneal ring segments implantation for keratoconus treatment:a pilot study

Background:To analyze the clinical results of an artificial neural network(ANN)that has been processed in order to improve the predictability of intracorneal ring segments(ICRS)implantation in keratoconus.Methods:This retrospective,comparative,nonrandomized,pilot,clinical study included a cohort of 20 keratoconic eyes implanted with intracorneal ring segments KeraRing(Mediphacos,Belo Horizonte,Brazil)using the ANN(ANN group)and 20 keratoconic eyes implanted with KeraRing using the manufacturer's nomograms(nomogram group).Uncorrected distance visual acuity(UDVA),corrected distance visual acuity(CDVA)(visual acuity is expressed in decimal value and in logMAR value in brackets),manifest refraction,corneal topography,tomography,aberrometry,pachymetry and volume analysis(Sirius System,CSO,Firenze,Italy)were performed during the preoperative visit;and the two groups,ANN group and nomogram group,did not differ significantly preoperatively in all of the parameters evaluated.These preoperative values were compared with the results obtained at the third-month visit.Mann-Whitney test and Wilcox on test were used for the statistical analyses.Results:The spherical equivalent and the keratometric values decreased significantly in both groups.The CDVA improved from 0.60±0.23(0.22 logMAR)preoperatively to 0.73±0.21(0.14 logMAR)postoperatively in the ANN group(P<0.005),and from 0.54±0.19(0.27 logMAR)preoperatively to 0.62±0.19(0.21 logMAR)postoperatively in the nomogram group(P<0.01),with statistically significant difference between the two groups(P<0.05),being better in the ANN group.Coma-like aberrations decreased significantly in the ANN group,while in the nomogram group they did not change significantly,but no statistically significant difference was found between the two groups.Con elusions:ANN to guide ICRS provides an increase in the visual acuity,reduction in the spherical equivalent and improvement in the optical quality of keratoconus patients.ANN gives better results when compared with the manu facturer's no mograms in terms of better corrected vision and reduction of the coma-like aberrations.The constant inclusion of new cases will make the predictability of ANN increasingly better as the software finetunes its learning.

Corneal transplantation outcomes after the extrusion of an intrastromal keratoprosthesis:a pilot study

This short report includes 5 eyes of 5 patients(mean age 63.2±12 years)who underwent a tectonic keratoplasty[deep anterior lamellar keratoplasty(DALK)or penetrating keratoplasty(PK)]in order to rehabilitate the eye after the extrusion of the non-perforating keratoprosthesis(Kpro)KeraKlear(KeraMed,USA).The non-perforating Kpro was extruded after a mean period of 21.4±21.8 months due to melting.In two cases,the keratoplasty was performed the same day of the non-perforating Kpro removal due to a severe melting,while in the other three cases it was performed 1 to 3 months later.Two eyes received a DALK,but in 3 eyes a macroscopic Descemetzs membrane perforation forced the conversion into a PK.The mean follow-up period after the keratoplasty was 16.8±6.6 months.No cases of rejection were recorded.All the 5 eyes achieved"anatomical success"(transparent graft,with no signs of infection or inflammation).Two eyes showed limited functional success"because the achievement of the best visual potential was prevented by the development of glaucomatous optic atrophy during the follow-up period.In conclusion,this short report presents an unexpected success of a keratoplasty performed with a tectonic purpose after the extrusion of the non-perforating Kpro because the corneal graft remained transparent,without neovascularization or scarring during the follow-up period.This initial evidence shows some encouraging results reg a rd i ng graft survival rate and the achievement of a useful visual rehabilitation with keratoplasty after a nonperforating Kpro failure in stead of repeating the Kpro implantation.

Clinical outcomes with a newvdesign in multifocal intraocular lens:a pilot study

Purpose:To evaluate the clinical and visual outcomes,quality of near vision and the influence of photic phenomena in patients bilaterally implanted with a new Precizon Presbyopic multifocal intraocular lens(IOL).Methods:In this prospective consecutive case series,20 eyes of 10 patients were included(mean age 63.80±12.55 years).Uncorrected and corrected visual acuity(far,intermediate and near),subjective refraction,binocular defocus curve,contrast sensitivity(CSV-1000)and quality of vision and satisfaction questionnaires were measured.The follow-up was 12 months after surgery.Results:At 12 months after surgery,uncorrected distance visual acuity(UDVA)improved with surgery(P=0.001)with a value of 0.08±0.08 logMAR.Uncorrected near visual acuity(UNVA)was 0.22±0.12 logMAR and distance corrected near visual acuity(DCNVA)was 0.16±0.13 logMAR.Intermediate distance visual acuity(UIVA)was 0.22±0.10 logMAR.Contrast sensitivity outcomes were similar to normal population in photopic conditions and slightly reduced in mesopic conditions of lighting.Defocus curve showed that this multifocal iOL was able to provide a visual acuity(VA)equal to or better than 0.16 logMAR between defocus levels of+1.00 to-2.50 D.Good patient satisfaction was obtained in quality of vision and satisfaction questionnaires outcomes.Conclusions:The Precizon Presbyopic NVA IOL(OPHTEC BV)provides good visual outcomes.This multifocal IOL provides a high percentage of spectacle independence due to good VA at far,intermediate and near distances and satisfactory contrast sensitivity.High patient satisfaction was observed in quality of vision and satisfaction questionnaires with a low percentage of patients manifesting photic phenomena.

Corneal transplantation outcomes after the extrusion of an intrastromal keratoprosthesis:a pilot study

This short report includes 5 eyes of 5 patients(mean age 63.2±12 years)who underwent a tectonic keratoplasty[deep anterior lamellar keratoplasty(DALK)or penetrating keratoplasty(PK)]in order to rehabilitate the eye after the extrusion of the non-perforating keratoprosthesis(Kpro)KeraKlear(KeraMed,USA).The non-perforating Kpro was extruded after a mean period of 21.4±21.8 months due to melting.In two cases,the keratoplasty was performed the same day of the non-perforating Kpro removal due to a severe melting,while in the other three cases it was performed one to 3 months later.Two eyes received a DALK,but in 3 eyes a macroscopic Descemet membrane perforation forced the conversion into a PK.The mean follow-up period after the keratoplasty was 16.8±6.6 months.No cases of rejection were recorded.All the 5 eyes achieved“anatomical success”(transparent graft,with no signs of infection or inflammation).Two eyes showed limited“functional success”because the achievement of the best visual potential was prevented by the development of glaucomatous optic atrophy during the follow-up period.In conclusion,this short report presents an unexpected success of a keratoplasty performed with a tectonic purpose after the extrusion of the non-perforating Kpro because the corneal graft remained transparent,without neovascularization or scarring during the follow-up period.This initial evidence shows some encouraging results regarding graft survival rate and the achievement of a useful visual rehabilitation with keratoplasty after a nonperforating Kpro failure instead of repeating the Kpro implantation.

Reply to the letter to the editor

We appreciate the interest of Miguel Faria Ribeiro in our paper[1],as well as the comments made to it.The interest of the topic is sound,as nowadays an enormous amount of new so-called“premium lenses”are appearing in the market,with different optical profiles which obviously lead to different light distributions and different quality of retinal image.This is why our interest in this topic is longstanding and we have published extensive summaries about the outcomes and complications of multifocal lenses over the last years[2,3].