AIM:To compare simultaneous corneal collagen cross-linking(CXL)with intracorneal ring segment(ICRS)implantation versus successive ICRS followed by CXL and detect the impact of the timing of CXL after ICRS implantation...AIM:To compare simultaneous corneal collagen cross-linking(CXL)with intracorneal ring segment(ICRS)implantation versus successive ICRS followed by CXL and detect the impact of the timing of CXL after ICRS implantation in the successive method.METHODS:This is a retrospective study of the records of three groups of patients.Group 1 of 28 patients were operated on with simultaneous ICRS implantation and CXL,group 2 of 32 patients had ICRS implantation followed by CXL after 1mo,and group 3 of 38 patients had ICRS implantation followed by CXL after 3mo.The three groups had follow-up visits after 6,12,and 24mo.RESULTS:The preoperative data,age,and gender differences among 3 groups revealed no significant differences.The postoperative spherical equivalent and best-corrected visual acuity were improved significantly in all groups compared to the baseline,which were more evident in groups 1 and 2.The differences between preoperative and postoperative mean values of mean of K readings(Km)and maximum K reading(Kmax)at 6mo were 4.66 and 4.1 D in group 1,4.43 and 4.64 D in group 2,but 3.2 and 3.4 D in group 3,respectively.The spherical aberrations and the vertical coma showed significant postoperative changes in all groups,and trefoil showed nonsignificant changes.CONCLUSION:Simultaneous and sequential ICRS implantation and CXL at 1mo has similar Km and Kmax better postoperative changes than when both surgeries were done at three-month intervals.展开更多
AIM：To represent mathematically the intersection between the ectatic corneal geometry and the plane of intracorneal ring implants（ICRS）in order to determine the corneal response to ICRS surgery in keratoconus（KC）...AIM：To represent mathematically the intersection between the ectatic corneal geometry and the plane of intracorneal ring implants（ICRS）in order to determine the corneal response to ICRS surgery in keratoconus（KC）.Thereafter,to present the concept and early results of a newly derived topography-guided nomogram for ICRS surgery for the treatment of keratectasia. METHODS：The corneal rings plane intersection was modelled to a conic section. Ring effect was the result of：the ring size,position（steep vs flat）,location（distance from the geometric centre of the cornea）,and the discrepancy between the ring＇s curvature and the tunnel＇s curvature.Femtosecond laser was used to create the tunnels and the incision sites were chosen according to the nomogram in order to place the thickest ring in the steepest portion of the cornea regardless of the astigmatism axis of refraction.RESULTS：The conic section had a more prolate shape in the steep area of the cornea than in the flat area,depending on the corneal sagittal curvature. Equal ring size had more flattening effect in the steep area than in the flat area. Thick segment should be implanted under the steep portion of the cornea regardless of the cylinder axis of refraction. Single segment in the steep area was sufficient in early and moderate cases of KC. The new nomogram provided more topographic regularity with significant reduction of astigmatism and better improvement in uncorrected visual acuity（UCVA）and best-corrected visual acuity（BCVA）than the conventional nomogram. CONCLUSION：The newly derived nomogram can produce better results than the conventional nomogram. Moreover,based on this concept,a new nomogram can be integrated into the femtosecond laser software to create topography-guided,customized,elliptical tunnels with modified focal asphericity that allows for customized focal flattening of the irregularly steepened ectatic cornea.展开更多
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...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.展开更多
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...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.展开更多
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...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.展开更多
Background:To compare the results of single versus double intracorneal ring segment(ICRS)(KeraRing)implantation in keratoconus with respect to different cone locations.Methods:Twenty-two eyes of 18 patients with total...Background:To compare the results of single versus double intracorneal ring segment(ICRS)(KeraRing)implantation in keratoconus with respect to different cone locations.Methods:Twenty-two eyes of 18 patients with totally asymmetric cones(20-80%or 0-100%distribution along steep axis)were implanted with single ICRS(Group 1),38 eyes of 32 patients with central or partially asymmetric cones(50-50%or 40-60%distribution along steep axis)were implanted with double ICRS(Group 2),at a depth of 80%of the site of implantation,in channels created with femtosecond laser device.All patients had uncorrected and corrected distance visual acuities(UDVA and CDVA,respectively)of≤0.3 Snellen lines.Results:In both groups,patients had median UDVA and CDVA gain of 3 Snellen lines(P>0.05).Postoperative improvement in indices of vertical asymmetry and height decentration in Group 1;simulated keratometry,corneal astigmatism and anterior corneal asphericity values in Group 2 were greater(P<0.05).A total of 10 eyes(45.5%)in Group 1 were recommended double ring implantation by the manufacturer’s nomogram,but underwent single ICRS implantation and achieved visual,refractive,tomographic outcomes comparable to that in Group 2,although corneal cylindrical correction was less and final topographic astigmatism was greater.Conclusion:Double ICRS implantation seems to be superior in terms of keratometry,corneal astigmatism and anterior corneal asphericity improvement.Single ICRS implantation in totally asymmetric cones seems to provide satisfactory visual,refractive and tomographic results,similar to double ICRS implantation in central and partially asymmetric cones,by inducing central shift of the cone.展开更多
AIM: To investigate the efficacy of Ferrara rings (FR) implantation in the treatment of keratoconus.METHODS: It was a retrospective case series descriptive study. The sample was comprised of 50 patients 79 eyes diagno...AIM: To investigate the efficacy of Ferrara rings (FR) implantation in the treatment of keratoconus.METHODS: It was a retrospective case series descriptive study. The sample was comprised of 50 patients 79 eyes diagnosed with progressive keratoconus. This included 24 (48%) males and 26 (52%) females between the age of 13 and 44 years. All participants underwent surgical implantation of FR in the period between January 2009 and September 2010 at Jordan University Hospital. Thorough ophthalmologic examinations were applied to measure vital variables for each pathological condition before and after surgery. RESULTS: Findings indicated an overall significant postoperative improvement in both uncorrected visual acuity (UCVA) and best spectacle corrected visual acuity (BSCVA) throughout follow up visits. Moreover, results illustrated a significant decrease in spherical equivalent (SE) and keratometric readings (lower, higher and the average). CONCLUSION: Surgical intervention strategies are being frequently developed to meet the needs of patients with keratoconus. The implantation of Ferrara rings has proven to be a safe and feasible alternative procedure for the treatment of mild-moderate keratoconus especially for patients with contact lenses intolerance. We have found that this procedure has improved visual outcomes in all eyes studied. Nevertheless, further research is needed to investigate long term outcomes.展开更多
AIM:To evaluate the short-term clinical outcomes of Ferrara rings in keratoconus using an optimized nomogram developed after several years of research and retrospective analysis of clinical data.METHODS:This prospecti...AIM:To evaluate the short-term clinical outcomes of Ferrara rings in keratoconus using an optimized nomogram developed after several years of research and retrospective analysis of clinical data.METHODS:This prospective longitudinal non-comparative clinical trial evaluated 88 eyes of 88 patients(age 18-62 y)with keratoconus diagnosis from two Spanish centers.Ferrara ring segment(AJL Ophthalmic)implantation was performed in all cases,using the mechanical procedure in 25 eyes(28.4%)and a femtosecond laser-assisted procedure in 63 eyes(71.6%).The ring segments implanted in each case were selected using a new optimized nomogram that considered variables such as anterior corneal asphericity and astigmatism or the discrepancy among astigmatism and coma orientations.Visual,refractive,corneal topographic,aberrometric,and pachymetric changes after surgery were evaluated during a 3-month follow-up.RESULTS:The implants induced a significant refractive change as well as an improvement in uncorrected(UDVA)and corrected distance visual acuity(CDVA;P<0.001).Postoperative CDVA of 0.10 log MAR or better was achieved in 28.4%and 46.5%of eyes,respectively.Two eyes(2.3%)lost two or more lines of CDVA whereas a total of 53.5%of eyes gained lines of CDVA.A significant central anterior and posterior corneal flattening was induced(P≤0.003),with a significant reduction of anterior(P<0.001)and posterior corneal astigmatisms(P=0.048),and a change in anterior asphericity(P<0.001).Total primary coma(6 mm pupil)change was also statistically significant(preoperative 3.66±3.04μm vs postoperative 2.33±2.26μm,P<0.001).No significant differences were found in the effect of ring segments between cases implanted using the mechanical and femtosecond techniques(P≥0.101).CONCLUSION:The implantation of Ferrara rings based on the nomogram evaluated is safe and effective for promoting a visual rehabilitation in keratoconus,with a relevant control of primary coma aberration.展开更多
Several treatment options corresponding to the grade of keratoconus have been established.These are ultra-violet corneal crosslinking and intracorneal ring segments for mild to moderate keratoconus,and penetrating ker...Several treatment options corresponding to the grade of keratoconus have been established.These are ultra-violet corneal crosslinking and intracorneal ring segments for mild to moderate keratoconus,and penetrating keratoplasty or deep anterior lamellar keratoplasty for the more advanced cases of keratoconus.Bowman layer transplantation was developed as a procedure for patients with advanced,progressive keratoconus.The technique consists of transplanting an isolated donor Bowman layer into a mid-stromal pocket of a keratoconic cornea resulting in corneal flattening and stabilization against further ectasia.Thus,it aims at corneal stabilization in eyes with advanced keratoconus,and enabling continued contact lens wear for normal visual functionality.By being a sutureless procedure and using an acellular graft,it potentially avoids commonly known suture and graftrelated complications of penetrating or deep anterior lamellar keratoplasty.The treatment seems to be a promising option in the management of advanced keratoconus in order to postpone or prevent a more invasive corneal surgery,while minimizing the risk of complications and allowing less stringent surveillance and less intensive medical therapy.展开更多
文摘AIM:To compare simultaneous corneal collagen cross-linking(CXL)with intracorneal ring segment(ICRS)implantation versus successive ICRS followed by CXL and detect the impact of the timing of CXL after ICRS implantation in the successive method.METHODS:This is a retrospective study of the records of three groups of patients.Group 1 of 28 patients were operated on with simultaneous ICRS implantation and CXL,group 2 of 32 patients had ICRS implantation followed by CXL after 1mo,and group 3 of 38 patients had ICRS implantation followed by CXL after 3mo.The three groups had follow-up visits after 6,12,and 24mo.RESULTS:The preoperative data,age,and gender differences among 3 groups revealed no significant differences.The postoperative spherical equivalent and best-corrected visual acuity were improved significantly in all groups compared to the baseline,which were more evident in groups 1 and 2.The differences between preoperative and postoperative mean values of mean of K readings(Km)and maximum K reading(Kmax)at 6mo were 4.66 and 4.1 D in group 1,4.43 and 4.64 D in group 2,but 3.2 and 3.4 D in group 3,respectively.The spherical aberrations and the vertical coma showed significant postoperative changes in all groups,and trefoil showed nonsignificant changes.CONCLUSION:Simultaneous and sequential ICRS implantation and CXL at 1mo has similar Km and Kmax better postoperative changes than when both surgeries were done at three-month intervals.
文摘AIM：To represent mathematically the intersection between the ectatic corneal geometry and the plane of intracorneal ring implants（ICRS）in order to determine the corneal response to ICRS surgery in keratoconus（KC）.Thereafter,to present the concept and early results of a newly derived topography-guided nomogram for ICRS surgery for the treatment of keratectasia. METHODS：The corneal rings plane intersection was modelled to a conic section. Ring effect was the result of：the ring size,position（steep vs flat）,location（distance from the geometric centre of the cornea）,and the discrepancy between the ring＇s curvature and the tunnel＇s curvature.Femtosecond laser was used to create the tunnels and the incision sites were chosen according to the nomogram in order to place the thickest ring in the steepest portion of the cornea regardless of the astigmatism axis of refraction.RESULTS：The conic section had a more prolate shape in the steep area of the cornea than in the flat area,depending on the corneal sagittal curvature. Equal ring size had more flattening effect in the steep area than in the flat area. Thick segment should be implanted under the steep portion of the cornea regardless of the cylinder axis of refraction. Single segment in the steep area was sufficient in early and moderate cases of KC. The new nomogram provided more topographic regularity with significant reduction of astigmatism and better improvement in uncorrected visual acuity（UCVA）and best-corrected visual acuity（BCVA）than the conventional nomogram. CONCLUSION：The newly derived nomogram can produce better results than the conventional nomogram. Moreover,based on this concept,a new nomogram can be integrated into the femtosecond laser software to create topography-guided,customized,elliptical tunnels with modified focal asphericity that allows for customized focal flattening of the irregularly steepened ectatic cornea.
文摘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.
文摘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.
文摘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.
文摘Background:To compare the results of single versus double intracorneal ring segment(ICRS)(KeraRing)implantation in keratoconus with respect to different cone locations.Methods:Twenty-two eyes of 18 patients with totally asymmetric cones(20-80%or 0-100%distribution along steep axis)were implanted with single ICRS(Group 1),38 eyes of 32 patients with central or partially asymmetric cones(50-50%or 40-60%distribution along steep axis)were implanted with double ICRS(Group 2),at a depth of 80%of the site of implantation,in channels created with femtosecond laser device.All patients had uncorrected and corrected distance visual acuities(UDVA and CDVA,respectively)of≤0.3 Snellen lines.Results:In both groups,patients had median UDVA and CDVA gain of 3 Snellen lines(P>0.05).Postoperative improvement in indices of vertical asymmetry and height decentration in Group 1;simulated keratometry,corneal astigmatism and anterior corneal asphericity values in Group 2 were greater(P<0.05).A total of 10 eyes(45.5%)in Group 1 were recommended double ring implantation by the manufacturer’s nomogram,but underwent single ICRS implantation and achieved visual,refractive,tomographic outcomes comparable to that in Group 2,although corneal cylindrical correction was less and final topographic astigmatism was greater.Conclusion:Double ICRS implantation seems to be superior in terms of keratometry,corneal astigmatism and anterior corneal asphericity improvement.Single ICRS implantation in totally asymmetric cones seems to provide satisfactory visual,refractive and tomographic results,similar to double ICRS implantation in central and partially asymmetric cones,by inducing central shift of the cone.
文摘AIM: To investigate the efficacy of Ferrara rings (FR) implantation in the treatment of keratoconus.METHODS: It was a retrospective case series descriptive study. The sample was comprised of 50 patients 79 eyes diagnosed with progressive keratoconus. This included 24 (48%) males and 26 (52%) females between the age of 13 and 44 years. All participants underwent surgical implantation of FR in the period between January 2009 and September 2010 at Jordan University Hospital. Thorough ophthalmologic examinations were applied to measure vital variables for each pathological condition before and after surgery. RESULTS: Findings indicated an overall significant postoperative improvement in both uncorrected visual acuity (UCVA) and best spectacle corrected visual acuity (BSCVA) throughout follow up visits. Moreover, results illustrated a significant decrease in spherical equivalent (SE) and keratometric readings (lower, higher and the average). CONCLUSION: Surgical intervention strategies are being frequently developed to meet the needs of patients with keratoconus. The implantation of Ferrara rings has proven to be a safe and feasible alternative procedure for the treatment of mild-moderate keratoconus especially for patients with contact lenses intolerance. We have found that this procedure has improved visual outcomes in all eyes studied. Nevertheless, further research is needed to investigate long term outcomes.
基金Supported by the Ministry of Economy, Industry and Competitiveness of Spain within the program Ramón y Cajal (RYC-2016-20471)
文摘AIM:To evaluate the short-term clinical outcomes of Ferrara rings in keratoconus using an optimized nomogram developed after several years of research and retrospective analysis of clinical data.METHODS:This prospective longitudinal non-comparative clinical trial evaluated 88 eyes of 88 patients(age 18-62 y)with keratoconus diagnosis from two Spanish centers.Ferrara ring segment(AJL Ophthalmic)implantation was performed in all cases,using the mechanical procedure in 25 eyes(28.4%)and a femtosecond laser-assisted procedure in 63 eyes(71.6%).The ring segments implanted in each case were selected using a new optimized nomogram that considered variables such as anterior corneal asphericity and astigmatism or the discrepancy among astigmatism and coma orientations.Visual,refractive,corneal topographic,aberrometric,and pachymetric changes after surgery were evaluated during a 3-month follow-up.RESULTS:The implants induced a significant refractive change as well as an improvement in uncorrected(UDVA)and corrected distance visual acuity(CDVA;P<0.001).Postoperative CDVA of 0.10 log MAR or better was achieved in 28.4%and 46.5%of eyes,respectively.Two eyes(2.3%)lost two or more lines of CDVA whereas a total of 53.5%of eyes gained lines of CDVA.A significant central anterior and posterior corneal flattening was induced(P≤0.003),with a significant reduction of anterior(P<0.001)and posterior corneal astigmatisms(P=0.048),and a change in anterior asphericity(P<0.001).Total primary coma(6 mm pupil)change was also statistically significant(preoperative 3.66±3.04μm vs postoperative 2.33±2.26μm,P<0.001).No significant differences were found in the effect of ring segments between cases implanted using the mechanical and femtosecond techniques(P≥0.101).CONCLUSION:The implantation of Ferrara rings based on the nomogram evaluated is safe and effective for promoting a visual rehabilitation in keratoconus,with a relevant control of primary coma aberration.
文摘Several treatment options corresponding to the grade of keratoconus have been established.These are ultra-violet corneal crosslinking and intracorneal ring segments for mild to moderate keratoconus,and penetrating keratoplasty or deep anterior lamellar keratoplasty for the more advanced cases of keratoconus.Bowman layer transplantation was developed as a procedure for patients with advanced,progressive keratoconus.The technique consists of transplanting an isolated donor Bowman layer into a mid-stromal pocket of a keratoconic cornea resulting in corneal flattening and stabilization against further ectasia.Thus,it aims at corneal stabilization in eyes with advanced keratoconus,and enabling continued contact lens wear for normal visual functionality.By being a sutureless procedure and using an acellular graft,it potentially avoids commonly known suture and graftrelated complications of penetrating or deep anterior lamellar keratoplasty.The treatment seems to be a promising option in the management of advanced keratoconus in order to postpone or prevent a more invasive corneal surgery,while minimizing the risk of complications and allowing less stringent surveillance and less intensive medical therapy.
