Clinical outcomes after implantation of a new intrastromal corneal ring with 140-degree of arc in patients with corneal ectasia

AIM：To evaluate the clinical and tomographic outcomes after implantation of a new intrastromal corneal ring segment（ICRS） with 140-degrees of arc in eyes with corneal ectasia.METHODS：We evaluated patients with corneal ectasia implanted with Ferrara 140° ICRS from April 2010 to February 2015.Outcome measures included preoperative and postoperative corrected distance visual acuity（CDVA）,keratometry simulated（K） reading,tomographic astigmatism and asphericity.All patients were evaluated using the Pentacam Scheimpflug system.RESULTS：The study evaluated 58 eyes.The mean followup was 16.81±10.8 mo.The CDVA（logM AR） improved from 0.5±0.20（20/60） to 0.3±0.21（20/40）（P〈0.01）.The average K reduced from 49.87±7.01 to 47.34±4.90 D（P〈0.01）.The asphericity changed from-0.60±0.86 to-0.23±0.67 D（P〈0.01）.The mean preoperative tomographic astigmatism decreased from-8.0±3.45 to-4.53±2.52 D（P〈0.01）.CONCLUSION：The new ICRS model with 140-degrees of arc effectively improve the visual acuity and reduce the high astigmatism usually found in patients with corneal ectasia.

Ferrara ring segments implantation for treating keratoconus

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.

Clinical outcomes after intrastromal corneal ring segments reoperation in keratoconus patients

AIM:To evaluate the clinical outcomes after Ferrara intrastromal corneal ring segments(ICRS)reoperation in patients with keratoconus.METHODS:A total of 37 keratoconus eyes implanted with intrastromal corneal ring segments,which had an ICRS exchange,addition,reposition or removal were evaluated.Uncorrected visual acuity(UCVA),best corrected visual acuity(BCVA),keratometry(K),asphericity(Q)and pachymetry at the thinnest point(PTP)of the cornea were evaluated using a corneal tomography(Oculus Pentacam,USA)RESULTS:The mean follow-up time after the reoperation was 30.5±9.7 months.The mean UCVA improved from 20/300 to 20/80(P=0.005);the mean BCVA improved from 20/160 to 20/50(P=0.0002),the mean keratometry reduced from 49.33±4.19D to 46.16±3.90D(P=0.0001),the mean pachymetry at the thinnest point increased from 450±42.9μm to 469±40.8μm(P=0.0001).The asphericity increased from-0.84±0.74 to-0.35±0.81(P=0.15)and the spherical equivalent reduced from-4.64±4.87D to-3.04±3.45D(P=0.137).The changes in the asphericity and spherical equivalent were not statistically significant.CONCLUSION:Ferrara ICRS implantation showed to be a reversible and readjustable surgical procedure for keratoconus treatment.Good outcomes can be obtained even after removal,addition,reposition or exchange of ICRS.

Investigation of the efficiency of intrastromal ring segments with cross-linking using different sequence and timing for keratoconus

· AIM: To evaluate and compare the efficacy and stability of intrastromal corneal ring segment(ICRs)implantation with cross-linking(CXL) using different sequence and timing.· METHODS: In this single retrospective study, 86 keratoconic eyes subjected the ICRs implantation. We analyzed only 41 eyes that had complete follow-ups.They were divided into three groups: ICRs implantation was applied only(group normal), ICRs first followed by CXL immediately(group CXL-S), CXL first followed by ICRs long after(group CXL-B). The visual acuity,refractive results, keratometry were compared preoperatively and 1y postoperatively. Their differences among the three groups were also analyzed.·RESULTS: Group normal comprised 25 eyes, group CXL-S 8 eyes, and group CXL-B 8 eyes. There were improvements in the mean uncorrected distance visual acuity(UDVA) and the mean corrected distance visual acuity(CDVA) compared preoperatively and 1y postoperatively [UDVA: 0.31(P =0.030) logarithmic minimum angle of resolution(log MAR) group normal, 0.4(P =0.020) group CXL-S, 0.45(P =0.001) group CXL-B;CDVA : 0. 21 log MAR( P = 0. 013) group normal, 0. 30(P =0.036) group CXL-S; 0.26(P =0.000) group CXL-B].The refractive and topographic outcomes also showed improvements. In terms of comparisons among the three groups, all the P values were above 0.05, showing no significant difference. But only group CXL-B had improvement in UDVA and CDVA for all the patients.·CONCLUSION: With safety and good visual outcomes,ICRs implantation is a viable alternative for keratoconus.No significant difference was found among these three groups.

Preliminary results of a new intrastromal corneal ring segment as a tissue saving procedure in photorefractive keratectomy to correct moderate to high myopia

AIM:To evaluate the clinical results after implantation of a new intrastromal corneal ring segment(ICRS)associated with photorefractive keratectomy(PRK)to correct high myopia(HM)patients with thin corneas.METHODS:We evaluated 42 eyes of 23 HM patients that had ICRS implantation followed by PRK.The mean age of patients was 29.1±7.12 y(range 18 to 40 years old).Uncorrected visual acuity(UCVA),best corrected visual acuity(BCVA),keratometry,spherical equivalent,pachymetry,and aberrometry were compared using ANOVA with repeated measurements evaluated preoperatively and at last follow-up visit after the procedures.The refractive predictability and simulated/real corneal ablation were also assessed.RESULTS:The mean follow-up time after PRK was 6.8±1.6 mo.The mean preoperative UCVA improved from 20/800 preoperative to 20/100 after ICRS and 20/35 after PRK.The mean preoperative BCVA was 20/25(range from 20/30 to 20/20)and remained unchanged after ICRS implantation.Following the PRK the mean BCVA was 20/25(range from 20/30 to 20/20).The mean spherical equivalent decreased from-7.25±1.12(range-5.00 to-9.00)preoperatively to-3.32±1.0(range-2.00 to-5.00)postoperatively(P<0.001)after ICRS implantation and decreased from-2.44±1.51 preoperatively to 0.32±0.45(range-0.625 to 0.875)postoperatively(P<0.001)after PRK.The change in BCVA and topographic astigmatism was statistically significant(P<0.0001).CONCLUSION:ICRS in HM associated with PRK can be a tissue saving procedure and an alternative surgical option for correction of moderate to high myopia.

Evaluation of a new nomogram for Ferrara ring segment implantation in keratoconus

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.

Double intrastromal corneal ring segment implantation: a new approach for improved clinical outcomes in keratoconus patients

AIM:To evaluate the clinical outcomes after subsequent implantation of a new intrastromal corneal ring segment(ICRS)model followed by an additional short-arc ICRS implant in keratoconus patients.METHODS:This retrospective single-arm cohort study evaluated 25 eyes of 21 keratoconus patients implanted with the new ICRS followed by 140-arch length ICRS(140-ICRS)implantation.Uncorrected distance visual acuity(UDVA,logMAR),corrected distance visual acuity(CDVA,logMAR),sphere,astigmatism,keratometry,spherical equivalent(SE),and asphericity were compared preoperatively and postoperatively after both ICRS implantation.RESULTS:The average follow-up time after 140-ICRS implantation was 6.40±2.20mo.The mean preoperative UDVA improved from 1.27±0.14 preoperative to 0.52±0.26 after both ICRS implantation(P=0.03).The mean sphere value reduced from-5.34±2.74 preoperatively to-2.06±1.84 postoperatively(P<0.001)after the first ICRS implantation and decreased to-0.59±1.54 postoperatively(P<0.001)after 140-ICRS implantation.The mean preoperative astigmatism was-3.72±1.56 and improved to-2.82±1.08 after the first ICRS implantation,and following the 140-ICRS implantation,the mean astigmatism was-1.37±0.67(P=0.001).The SE and asphericity changes were statistically significant(P<0.001).The researchers did not find intraoperative or postoperative complications for both procedures.CONCLUSION:The combination of 2 different ICRSs can efficiently regularize the cornea,reduce the SE,and improve visual acuity in selected keratoconus patients.

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.

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.

The number of intracorneal ring segments in asymmetric and central cones

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.

Bowman layer transplantation in the treatment of keratoconus

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.