Pubblicazioni scientifiche

Clinical observation of transepithelial corneal collagen cross-linking by Iontophoresis of riboflavin in treatment of keratoconus.

Eye Sci. 2014 Sep;29(3):160-4.

Li N, Fan Z, Peng X, Pang X, Tian C.

To evaluate the efficacy and safety of transepithelial collagen cross-linking by iontophoretic delivery of riboflavin in treatment of progressive keratoconus.
Eleven patients (15 eyes) with progressive keratoconus were enrolled. After 0.1% riboflavin-distilled water solution was deliveried via transepithelial iontophpresis for 5 min with 1 mA current, and ultraviolet radiation (370 nm, 3 mW/cm2) was performed at a 1.5 cm distance for 30 min. The follow up were 6 months in all eyes. The uncorrected visual acuity, corrected visual acuity, endothelial cell counting, corneal thickness, intraocular pressure, corneal curvature, corneal topography, OCT and corneal opacity before and 6-month after surgery were analyzed.
At 6 month postoperatively, mean uncorrected visual acuity and corrected visual acuity changed from 0.36 to 0.30 and from 0.42 to 0.57 without statistical significance. The mean value of each index of corneal curvature declined without statistical significance.Kmax value dereased from 60.91 to 59.91, and the astigmatism declined from 3.86 to 3.19. Central corneal thickness decreased from 460.93 μm to 455.40 μm, and thinnest corneal thickness declined from 450.87 μm to 440.60 μm with no statistical significance. Intraocular pressure was significantly elevated from 10.85 mmHg to 12.62 mmHg. Endothelial cell count did not change significantly. No corneal haze occurred. Mean depth of corneal demarcation line was 288.46 μm at 1 month postoperatively.
Transepithelial corneal collagen cross-linking by iontophoresis is effective and safe in the treatment of progressive keratoconus, and yields stable clinical outcomes during 6-month follow up. However, long-term follow up is urgently required.

Structural modifications and tissue response after standard epi-off and iontophoretic corneal crosslinking with different irradiation procedures.

Invest Ophthalmol Vis Sci. 2014 Apr 17;55(4):2526-33

Mastropasqua L1, Lanzini M, Curcio C, Calienno R, Mastropasqua R, Colasante M, Mastropasqua A, Nubile M.

The aim of this study is to investigate modifications in human cadaver corneas after different crosslinking procedures, including standard epi-off treatment, iontophoresis imbibition, and different exposure to ultraviolet A (UVA) sources (30 minutes at 3 mW and 9 minutes at 10 mW).
A total of 12 human cadaver corneas was examined and divided as follows: 3 served as control (group 1), 3 were treated with a standard epi-off procedure (group 2), 6 underwent iontophoresis imbibition for 5 minutes, and then 3 were irradiated for 30 minutes with 3 mW UVA (group 3), and 3 for 9 minutes at 10 mW UVA (group 4). Deformation amplitude index was measured before and after the corneas underwent treatment. After treatment, corneas were prepared for hematoxylin-eosin and immunohistochemistry evaluation. The expression of TUNEL, matrix metalloproteinase-1 (MMP-1), collagen type I, and CD34 was investigate in all samples.
The deformation amplitude index decreased in all groups, in particular in group 4, indicating an improvement of corneal biomechanical properties. Immunohistochemical staining showed a significant stromal alteration in group 2, mild damage in group 3, and no modifications in corneal morphology in group 4. The TUNEL (P < 0.001) and MMP-1 (P = 0.002) positivity was more evident in group 4. Collagen type I positivity significantly increased in groups 3 (P = 0.002) and 4 (P = 0.002). The CD34 expression was more evident in groups 2 (P = 0.003) and 3 (P = 0.003).
Iontophoresis imbibition followed by UVA irradiation for 9 minutes at 10 mW determined less tissue damage and better stromal remodeling.

Intracorneal Ring Segment Implantation in Corneas with Post-Laser In Situ Keratomileusis Keratectasia

Ophthalmology Volume 116, Number 9, September 2009

David P. Piñero, MSc,1,2 Jorge L. Alio, MD, PhD,1,3 Antonio Uceda-Montanes, MD,4,5 Bassam El Kady, MD, PhD,1,6 Inmaculada Pascual, PhD2

Purpose: To evaluate the refractive and aberrometric changes in corneas with post-LASIK keratectasia implanted with intracorneal ring segments (ICRS) during a 2-year follow-up.
Design: Retrospective, consecutive case series.
Participants: Thirty-four eyes of 25 patients (age range, 20–59 years) with post-LASIK ectasia were included. Ectasia was diagnosed by slit-lamp appearance of corneal thinning, unstable topographic steepening, progressive corneal thinning on ultrasonic pachymetry, decreased visual acuity, and unstable refraction.
Methods: Intracorneal ring segment implantation was performed in all cases by 2 surgeons from 2 different ophthalmologic centers with the aim of correcting the spherocylindrical error and improving the visual quality. Corneal tunnels were created by means of mechanical dissection in 20 eyes and femtosecond laser technology in 14 eyes. Intacs (Addition Technology, Inc, Fremont, CA) were inserted in 24 eyes, and KeraRings (Mediphacos, Belo Horizonte, Brazil) in 10 eyes. In all cases a follow-up of 12 months was completed, with a total of 15 eyes examined 24 months after surgery.
Main Outcome Measures: Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, keratometry, and corneal aberrations.
Results: Uncorrected visual acuity did not improve after surgery (P 􏰄 0.17). Best spectacle-corrected visual acuity increased significantly at 6 months (P 􏰄 0.02). Some 38.89% of eyes gained 2 or more lines of BSCVA at 6 months, and this percentage increased to 60% at 24 months. There was a nonsignificant reduction of sphere at 6 months (P 􏰄 0.28). Manifest cylinder was reduced significantly during the postoperative follow-up (P 􏰄 0.05, preoperative to 6 months; P 􏰄 0.04, 6 –12 months). The cornea was on average flatter at 6 months (P􏰃0.01), with a posterior nonsignificant regression of the achieved flattening (P 􏰄 0.73). In regard to corneal aberrations, a statistically significant reduction was found in coma-like root mean square (RMS) (P 􏰄 0.03) after surgery. Segment ring explantation was performed in 6 eyes, and ring reposition was performed in 2 eyes. The apical curvature gradient was significantly higher in the group of explanted eyes (P 􏰄 0.03).
Conclusions: Intracorneal ring segment implantation is a useful option for the treatment of coma-like aberrations and astigmatism in post-LASIK corneal ectasia.
Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. Ophthalmology 2009;116:1665–1674 © 2009 by the American Academy of Ophthalmology.

One-Year Results of Intrastromal Corneal Ring Segment Implantation (KeraRing) using Femtosecond Laser in Patients with Keratoconus

Am J Ophthalmol 2008;145:775–779.


PURPOSE: To report the results of intrastromal corneal ring segment [ICRS] (KeraRing; Mediphacos, Belo Hori- zonte, Brazil) implantation using a femtosecond laser (IntraLase Corp, Irvine, California, USA) in keratoconic patients.
DESIGN: Retrospective, noncomparative, interventional study.
METHODS: Thirty-two keratoconic patients (50 eyes) who underwent ICRS insertion using a femtosecond laser for channel creation and completed at least one year of follow-up were included in this study. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, topographic findings, and adverse events were assessed.
RESULTS: No intraoperative complications were dem- onstrated in this series of patients. At the first postoper- ative day, segment migration to the incision site was seen in three eyes (6%; early postoperative complication). To avoid melting, we repositioned the migrated segment away from the incision site. Serious second migration was not seen and we did not need to reposition any segment again. At the last postoperative examination, there was a statistically significant reduction in the spherical equiv- alent refractive error compared with that observed at the examination before implantation (mean 􏰋 standard devi- ation, 􏰌5.62 􏰋 4.15 diopters [D; range, 􏰌23.62 to 0.50 D] to 􏰌2.49 􏰋 2.68 D [range, 􏰌11.12 to 3.5 D]; P < .001). The UCVA before implantation was 20/40 or worse in 47 eyes (94%; range, counting fingers to 20/30), whereas at the last follow-up examination, 14 (28%) of 50 eyes had a UCVA of 20/40 or better (range, counting fingers to 20/25). Nine eyes (18%) maintained the preimplantation BSCVA, whereas 39 eyes (68%) experienced a BSCVA gain of one to four lines at the last follow-up examination. Only in two eyes (4%; two patients) with advanced keratoconus (stage III) was there a decrease of up to two lines. Despite this deterio- ration in BSCVA, the patients did not want to remove
Accepted for publication Dec 14, 2007.
From the Dunya Eye Hospital, Istanbul, Turkey (E.C., S.A., E.A.); and
the Department of Ophthalmology, University of Crete, Heraklion, Crete, Greece (G.D.K., N.S.T., M.R.J., I.G.P.).
Inquiries to Nikolaos S. Tsiklis, Institute of Vision and Optics, University of Crete Medical School, Department of Ophthalmology, 71110 Heraklion, Crete, Greece; e-mail:
the ICRSs, because there was an increase of UCVA. No late postoperative complications were observed during the follow-up period.
CONCLUSIONS: ICRS (KeraRing) implantation using femtosecond laser for tunnel creation is a minimally invasive procedure for improving visual acuity (both UCVA and BSCVA) in keratoconic patients.

Modeling the Intracorneal Ring Segment Effect in Keratoconus Using Refractive, Keratometric, and Corneal Aberrometric Data

IOVS, November 2010, Vol. 51, No. 11

David P. Pin ̃ero,1,2 Jorge L. Alio,1,3 Miguel A. Teus,4,5 Rafael I. Barraquer,6 and Antonio Uceda-Montanes7

PURPOSE. To characterize the refractive, keratometric, and cor- neal aberrometric effect of a specific type of intracorneal ring segment (ICRS) as a function of its thickness and the preoper- ative conditions of the cornea.
METHODS. A total of 72 consecutive keratoconic eyes of 57 patients ranging in age from 15 to 68 years were retrospec- tively analyzed and included in the study. All cases had a diagnosis of keratoconus and had undergone implantation of a 160° arc-length KeraRing segment (Mediphacos, Belo Hori- zonte, Brazil), by femtosecond laser technology. Correlations between ring segment thickness and several clinical parame- ters were investigated. In addition, a multiple regression anal- ysis was performed to characterize all factors that influence the ring segment effect.
RESULTS. Significant reductions in central curvature, corneal astigmatism, and comalike aberrations were found after sur- gery (P 􏰀 0.03). Moderate and limited correlations were found between ring segment thicknesses and changes in mean kera- tometry and higher order aberrations (r 􏰀 0.50, P 􏰃 0.01). A consistent linear relationship of the superior ring segment thickness to the induced corneal changes, the preoperative cylinder, and the difference in thickness between inferior and superior segments was found (P 􏰃 0.01, R2 􏰄 0.91). An almost identical model was obtained for the inferior ring segment thickness with the only distinction in the factor being the thickness difference between segments (P 􏰃 0.01, R2 􏰄 0.64).
CONCLUSIONS. The selection of the ring segment to implant in keratoconus should be based, not only on refraction and sub- jective appearance of the corneal topographic pattern but also on corneal aberrometry. This highly customized selection would allow a more predictable outcome. (Invest Ophthalmol Vis Sci. 2010;51:5583–5591) DOI:10.1167/iovs.09-5017

Intrastromal Corneal Ring Segment Implantation for the Treatment of Keratoconus

Cornea  Volume 30, Number 1, January 2011

Anıl Kubaloglu, MD, Esin Sogutlu Sari, MD, Yasin Cinar, MD, Arif Koytak, MD, Ekrem Kurnaz, MD, and Yusuf O ̈zertu ̈rk, MD

Purpose: To evaluate the safety and efficacy of intrastromal corneal ring segment implantation using both mechanical and femtosecond- assisted tunnel creation for the treatment of patients with keratoconus.
Methods: A retrospective noncomparative interventional study including 96 eyes of 75 patients with keratoconus. All patients had contact lens intolerance and clear central corneas. Corneal tunnels were made using a femtosecond laser in 26 eyes (femtosecond group) and mechanically in 70 eyes (mechanical group). The Keraring (Mediphacos, Belo Horizonte, Brazil) was implanted in each eye, and a complete ophthalmic examination was performed, including visual acuity, refraction, and keratometric readings.
Results: The mean preoperative uncorrected visual acuity for all eyes was 1.40 6 0.39 logarithm of the minimal angle of resolution (logMAR) (mean 6 SD) and improved to 0.60 6 0.34 logMAR at the sixth month (n = 96, P , 0.001) and 0.50 6 0.32 (n = 54, P , 0.001) at the 18th month. The mean preoperative best spectacle–corrected visual acuity (BSCVA) for all eyes (n = 96) was 0.68 6 0.36 logMAR. The mean BSCVA was 0.29 6 0.21 (n = 96, P , 0.001) at the sixth month and improved to 0.26 6 0.20 (n = 54, P , 0.001) at the 18th month. There was a significant reduction in spherical equivalent refractive error from 25.88 6 3.65 diopters (D) (n = 96) to 22.26 6 1.98 D (n = 54, P , 0.001) at the 18th month. The mean preoperative maximum keratometry (Kmax) was 53.58 6 5.90 D and decreased to 49.02 6 4.70 (n = 96, P , 0.001) at 6 months and 48.57 6 4.36 D (n = 54, P , 0.001) at the 18th month. Sixth month results of the mechanical versus femtosecond groups were as follows: improvement in uncorrected visual acuity (2.08 vs. 1.50 lines), improvement in BSCVA (2.93 vs. 2.19), reduction in spherical equivalent (3.78 vs. 3.75 D), and reduction in maximum keratometry (4.66 vs. 4.62 D). There was no statistically significant difference between both groups for any parameter.
Conclusions: Keraring implantation is effective for the treatment of keratoconus, providing safety and good visual outcomes after both mechanical and femtosecond-assisted tunnel creation.

Intrastromal Corneal Ring Segment Implantation by Femtosecond Laser for the Correction of Residual Astigmatism After Penetrating Keratoplasty

Cornea  Volume 30, Number 12, December 2011

Tatiana Moura Bastos Prazeres, MD,* Allan Cezar da Luz Souza, MD,* Nicolas Cesa ́ rio Pereira, MD,* Fa ́bio Ursulino, MD,† Leon Grupenmacher, MD,* and Luciene Barbosa de Souza, MD*

Purpose: To evaluate the safety and efficacy of intracorneal ring segments (ICRSs) aided by femtosecond (FS) laser for the correction of residual astigmatism after penetrating keratoplasty (PKP).

Methods: This retrospective noncomparative study comprised 14 eyes of 14 patients with high astigmatism after PKP who had ICRS implantation by femtosecond laser. The study evaluated uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refractive astigmatism, and corneal maximum curvature.

Results: The CDVA postoperatively improved after 3 months (P , 0.001) and 6 months (P , 0.001) compared with CDVA preoperatively. The CDVA at 3 months was similar to that at 6 months (P . 0.999) as well as the UDVA (P = 0.276). The preoperative astigmatism was higher than that after surgery (P = 0.001). The preoperative maximum curvature was higher than that of the post- operative maximum curvature (P , 0.001).

Conclusions: The implantation of ICRSs using the femtosecond laser for residual astigmatism post-PKP was safe and showed satisfactory results. It reduced refractive astigmatism and maximum corneal curvature and improved UDVA and CDVA.

Key Words: intracorneal ring segment, penetrating keratoplasty, femtosecond laser, keratoconus

Femtosecond laser assisted intrastromal corneal ring segment (Keraring) implantation in keratoconus

Raciha Beril Küçümen, Demir Başar, Murat Levent Alimgil
Yeditepe University, Medicine Faculty, Department Of Ophthalmology, Istanbul, Turkey

PURPOSE: To report results of femtosecond laser assisted intrastromal corneal ring segment (Keraring) implantation in patients with keratoconus.

Material-METHODS: Twelve eyes of 10 patients with clinically and topographically verified keratoconus have been included in the study. Intrastromal corneal ring segments were implanted following tunnel creation by femtosecond laser. In one eye a single 210° Keraring segment has been implanted, one eye received double 90° Keraring segments, another eye received double 120° Keraring segments and 9 eyes received double 160° Keraring segments.

RESULTS: Mean age of patients was 32. 5 ± 9.4 years. No complication has occured during femtosecond laser and implantation stages of the operation. Mean uncorrected visual acuity has increased from 0.095 ± 0.095 ( 0.01-0.3) preoperatively to 0.30 ± 0.19 (0.1-0.67) at 6th postoperative month and this was statistically high significant (p=0.002). Mean best corrected visual acuity increased from 0.40 ± 0.30 ( 0.16-1.0) preoperatively to 0.55 ± 0.23 (0.2-1.0) at 6th postoperative month and this was statistically significant (p=0.02). Mean preoperative spherical refraction was -4.42 ± 4.11 diopters (D) (-14.00,+0.25 D) whereas mean postoperative spherical refraction at 6th month was -1.13 ± 1.39 D (-3.5,+1.00 D). Difference between mean preoperative spherical refraction and mean postoperative spherical refraction was statistically high significant (p=0.003).

Mean preoperative cylindrical refraction was -4.60 ± 2.74 D (-9.75, -0.50 D) and mean postoperative cylindrical refraction at 6th month was -1.67 ± 1.38 D (-4.50, 0.00 D), their difference was found to be statistically high significant (p= 0.005).

Mean preoperative spherical equivalence has changed from -5.96 ± 4.12 D (-15.00, -1.00 D) to – 1.93 ± 1.32 D (-4.25, +0.50 D) at 6th postoperative month and this was also statistically high significant (p=0.002).

CONCLUSION: Femtosecond laser assisted intrastromal corneal ring segment implantation (Keraring) is a safe and effective method for the correction of keratoconus.

Key words: Femtosecond laser, intrastromal corneal ring segments, keratoconus, Keraring Fonte: