Evaluation of anterior and posterior surfaces of the cornea using a dual Scheimpflug analyzer in keratoconus patients implanted with intrastromal corneal ring segments

AIM:To evaluate corneal parameters measured with a dual Scheimpflug analyzer in keratoconus patients implanted with intrastromal corneal ring segments(ICRS).METHODS:Fifty eyes of 40 keratoconus patients had Ferrara ICRS implantation from November 2010 to April2014.Uncorrected visual acuity(UCVA),best corrected visual acuity(BCVA),refraction,keratometry,asphericity,elevation,pachymetry,root mean square(RMS),spherical aberration and coma were studied.All patients were evaluated using a dual Scheimpflug system.RESULTS:The mean follow-up time after the procedure was 12.7mo.The mean UCVA improved from0.82 to 0.31(P<0.001);the mean BCVA improved from0.42 to 0.05(P<0.0001),the mean spherical refraction changed from-3.06 ±3.80 D to-0.80 ±2.5 D(P<0.0001)and the mean refraction astigmatism reduced from-4.51 ±2.08 D to-2.26±1.18 D(P<0.0001).The changes from preoperative to postoperative,in parameters of the anterior and posterior surface of the cornea,were statistically significant except the elevation posterior at the apex of the cornea and posterior asphericity.CONCLUSION:The implantation of Ferrara ICRS induces changes in both anterior and posterior surfaces of the cornea.

Comparison of clinical outcome of small-incision lenticule intrastromal keratoplasty and FS-LASIK for correction of moderate and high hyperopia

AIM:To compare the clinical outcome of small-incision lenticule intrastromal keratoplasty(s LIKE)and femtosecond laser-assisted in situ keratomileusis(FS-LASIK)for correction of moderate and high hyperopia.METHODS:A case-controlled clinical study was performed.Twenty right eyes of 20 moderate and high hyperopia patients underwent s LIKE(s LIKE group)and 22 right eyes of 22 moderate and high hyperopia patients underwent FS-LASIK(FS-LASIK group)were enrolled in this study from October 2015 to October 2017.Visual acuity,refractive error,corneal thickness,and keratometry were compared between the groups before and 1 y postoperatively.RESULTS:The postoperative uncorrected near visual acuity(UNVA)and uncorrected distance visual acuity(UDVA)were improved in the two groups.The UNVA reached J1 in 15 eyes(75.0%)in the s LIKE group and 5 eyes(22.7%)in the FS-LASIK group 1 y after surgery(χ2=11.476,P=0.001).The UDVA was equal or better than the preoperative CDVA in 16 eyes(80.0%)in the s LIKE group and 8 eyes(36.4%)in the FS-LASIK group,respectively(X2=8.145,P=0.004).No eyes lost any line of best-corrected visual acuity(BCVA)in either group.The amount of postoperative residual hyperopia in the s LIKE group was significantly less than in the FS-LASIK group(Z=-2.841,P=0.004).The postoperative keratometry and corneal thickness were significantly higher in the s LIKE group than in the FS-LASIK group(t=4.411,10.279,P<0.001).The SRI and SAI of the s LIKE group were significantly higher than that in the FS-LASIK group.There was no statistically significant difference in mean decentration between the two groups.CONCLUSION:s LIKE has better visual and refractive outcome than FS-LASIK for correction of moderate and high hyperopia.

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.

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.

Assessment of contrast sensitivity loss after intrastromal femtosecond laser and LASIK procedure

AIM: To assess the loss of contrast sensitivity(CS)function for INTRACOR or intrastromal femtosecond laser presbyopia procedure to conventional LASIK procedures.·METHODS: Patients were recruited from a refractive surgery center for either INTRACOR or conventional LASIK. INTRACOR was performed on 8 eyes and LASIK was performed for 40 eyes in an overlapping period. Preoperative evaluation and post-operative follow up for up to three months was done. Drops of CS in 4 spatial frequency(3 cpd, 6 cpd, 12 cpd and 18 cpd) right before and 3mo after the surgery were compared by Wilcoxon signed ranks test.· RESULTS: For INTRACOR, CS threshold showed significant drop at both glare and non-glare condition,the drop was seen in all 4 spatial frequency. The averaged loss over the 4 spatial frequencies 3mo after surgery was 1.18 for non-glare and 0.71 for glare. For LASIK the CS threshold drop was most significant in 12 cpd for glare.·CONCLUSION: INTRACOR procedure produces a gain of near vision for presbyopia patients but also introduces a high lost of contrast sensitivity plus worsen of vision quality. Pre-surgical patient selection and advise should be given with specific regards to night driving and glare conditions.

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.

Non-Penetrating Femtosecond Laser Intrastromal Astigmatic Keratotomy Performed during Laser-Assisted Cataract Surgery: Results on Keratometric Astigmatism

Purpose: To investigate the efficacy of non-penetrating femtosecond laser intrastromal astigmatic keratotomy (ISAK) in terms of topographic and refractive changes. Methods: Retrospective study including 42 eyes (35 patients) with a corneal astigmatism between 0.5 and 1.5 D. All eyes underwent femtosecond laser-assisted cataract surgery with ISAK for astigmatism management using the Catalys laser system (Johnson & Johnson Vision). Visual acuity, refraction, as well as corneal topographic and corneal endothelial cell density (ECD) changes were evaluated during a 12-month follow-up. Astigmatic changes were analyzed using the Alpins vector method. Results: A significant reduction in manifest cylinder was observed at 1 month postoperatively (p = 0.03), with no significant changes afterwards (p = 0.90). A total of 38.1%, 52.4% and 59.2% of eyes had a manifest cylinder of 0.50 D or lower preoperatively and at 1 and 12 months after surgery, respectively. A significant reduction was found in topographic astigmatism at 1 month postoperatively (p < 0.01), with an additionally small but statistically significant reduction afterwards (p < 0.01). No significant changes in postoperative uncorrected (p = 0.97) and corrected visual acuities (p = 0.40) were observed during the follow-up. There was a trend to undercorrection of corneal astigmatism that decreased significantly over time. This led to some variability in changes of refractive astigmatism. A small but significant reduction in ECD was observed at 1 month postoperatively (p Conclusions: Femtosecond laser assisted ISAK is an effective and safe option to reduce corneal astigmatism during cataract surgery and consequently refractive astigmatism.

Visual rehabilitation in low-moderate keratoconus:intracorneal ring segment implantation followed by same-day topography-guided photorefractive keratectomy and collagen cross linking

AIM:To present the results of same-day topographyguided photorefractive keratectomy(TG-PRK) and corneal collagen crosslinking(CXL) after previous intrastromal corneal ring segment(ISCR) implantation for keratoconus.METHODS:An experimental clinical study on twentyone eyes of 19 patients aged 27.1±6.6y(range 19-43y),with low to moderate keratoconus who were selected to undergo customized TG-PRK immediately followed by same-day CXL, 9mo after ISCR implantation in a university ophthalmology clinic. Refraction, uncorrected distance visual acuities(UDVA) and corrected distance visual acuities(CDVA), keratometry(K) values, central corneal thickness(CCT) and coma were assessed 3mo after TG-PRK and CXL.RESULTS:After TG-PRK/CXL: the mean UDVA(logMAR) improved significantly from 0.66 ±0.41 to 0.20 ±0.25(P <0.05); Kflatvalue decreased from: 48.44±3.66 D to43.71±1.95 D; Ksteepvalue decreased from 45.61±2.40 D to41.56±2.05 D; Kaveragealso decreased from 47.00±2.66 D to42.42 ±2.07 D(P <0.05 for all). The mean sphere andcylinder decreased significantly post- surgery from,- 3. 10 ± 2. 99 D to-0.11±0.93 D and from-3.68±1.53 to-1.11 ±0.75 D respectively, while the CDVA, CCT and coma showed no significant changes. Compared to postISCR, significant reductions(P <0.05 or all) in all K values,sphere and cylinder were observed after TG-PRK/CXL.CONCLUSION:Same-day combined topography-guided PRK and corneal crosslinking following placement of ISCR is a safe and potentially effective option in treating low-moderate keratoconus. It significantly improves all visual acuity, reduced keratometry, sphere and astigmatism, but causes no change in central corneal thickness and coma.