Ferrara Ring Research Articles

Ferrara ring and the nomogram as the main strategy for correcting keratoconus: a systematic review of clinical findings

Introduction: In the setting of corneal ectasias, keratoconus (KC) is a bilateral and asymmetrical disease that results in progressive thinning and tilting of the cornea, leading to irregular astigmatism and decreased visual acuity. The condition affects all ethnicities and both sexes. KC prevalence and incidence rates are close to between 0.2 and 4790 per 100,000 people and 1.5 and 25 cases per 100,000 person-years, respectively. For surgeons who implant Ferrara rings, the manufacturer has developed an online nomogram aimed at optimizing patient outcomes. Objective: The present study carried out a systematic review to present the main clinical outcomes of keratoconus treatment using the Ferrara ring. Methods: The systematic review rules of the PRISMA Platform were followed. The literature search was carried out from January to February 2023 in Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases. Scientific articles from the last 15 years were selected. The quality of the studies was based on the GRADE instrument. The risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: A total of 60 articles were found, of which only 21 were part of this systematic review, after an eligibility analysis.It was concluded that the insertion of Ferrara rings in keratoconic eyes with previous cross-linking history using the company's nomogram results in significant improvements in visual, refractive, and tomographic results. Corneal densitometry in the anterior layer of the cornea decreases after the implantation of intrastromal corneal ring segments and correlates with corneal keratometry. Over 5 years, Ferrara-type intrastromal corneal ring segment implantation is a safe, effective, and stable procedure for restoring vision in pediatric patients with keratoconus old.

Ferrara Rings for Visual Rehabilitation in Eyes with Keratoconus and Previous Cross-Linking Using the Ferrara Ring Nomogram.

Purpose: To report the visual, refractive and tomographic outcomes following the implantation of intrastromal corneal ring segments (ICRS) (Ferrara rings, AJL Ophthalmics, Miñano, Spain) in eyes with a history of keratoconus and corneal cross-linking using the Ferrara ring nomogram. Methods: Retrospective, interventional case series performed at the Corneoplastics Unit, Queen Victoria Hospital, East Grinstead, United Kingdom. Results: 21 eyes of 19 patients with a history of keratoconus and prior corneal collagen cross-linking had Ferrara Intrastromal Corneal Ring Segments implanted between December 2015 and October 2017. The number, thickness and length of ring segments was chosen based on the Ferrara ring company nomogram. Mean uncorrected visual acuity (UDVA) improved from 0.88 to 0.52 logMAR (p < 0.001). Mean corrected visual acuity (CDVA) improved from 0.47 to 0.36 logMAR (p = 0.046). The percentage of eyes achieving 20/40 UDVA and CDVA increased from 5% to 38% and from 38% to 67%, respectively. Of the eyes, 52.3% gained at least two lines of CDVA. The spherical equivalent improved from −7.51D to −3.76D (p < 0.001) and the refractive astigmatism magnitude improved from 5.14D to 2.76D (p = 0.004). There were significant improvements in the corneal tomography with mean keratometry (KM) improving from 50.40D (3.53) to 48.24D (3.00) (p = 0.01) and keratometric astigmatism magnitude improving from 5.14D (2.91) to 2.76D (1.67) (p = 0.004). Conclusion: Insertion of Ferrara rings in keratoconic eyes with a history of prior cross-linking using the company nomogram results in significant improvements in visual, refractive and tomographic outcomes.

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

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. This prospective longitudinal non-comparative clinical trial evaluated 88 eyes of 88 patients (age 18-62y) 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. 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 logMAR 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±3.04 µm vs postoperative 2.33±2.26 µm, 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). 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.

Myoring and Ferrara ring segment implantation using femtosecond laser for treatment of keratoconus

Purpose To compare visual acuity, refraction, and topographic corneal changes after implantation of a MyoRing versus Ferrara ring segment for management of keratoconus. Patients and methods This is a prospective nonrandomized clinical comparative study. Forty eyes of 25 patients with keratoconus grades 2–4 were included in the study and were divided into two groups: group A (MyoRing group) included 20 eyes of patients with keratoconus subjected to femtosecond laser-assisted MyoRing implantation and group B included 20 eyes of patients with keratoconus subjected to femtosecond laser-assisted Ferrara ring segment implantation. Results Forty eyes of 25 patients (12 males and 13 females) with keratoconus grades 2–4 were enrolled in this study. The mean age of the patients in group A was 26.62±6.18 years and in group B was 24.72±5.06 years. The mean central corneal thickness improved from 440.25 to 476.57 µm in group A and from 441.35 to 470.63 μm in group B. The mean keratometric (K) reading decreased from 49.97±14.26 to 44.55±2.16 D in group A and from 48.69+4.26 to 44.85±1.92 D in group B. There was a statistically significant improvement in the postoperative uncorrected distance visual acuity, corrected distance visual acuity, K readings, manifest spherical and cylindrical refractive errors, and spherical equivalent in both groups. No serious intraoperative complications were reported. Conclusion Both MyoRing and Ferrara ring segments are effective modalities for treatment of grades 2–4 keratoconus, but MyoRing had a superior capability in improving the keratoconus parameters as well as in halting the progression of the disease.

Comparative Study between Myoring and Ferrara Ring Intracorneal Implantation Using Femtosecond Laser for Treatment of Keratoconus

Background: Keratoconus is a bilateral progressive, non-inflammatory ectatic corneal disease characterized by changes in corneal collagen structure and organization. Though the etiology remains unknown, novel techniques are continuously emerging for the diagnosis and management of the disease. Intracorneal rings are an effective way for treating keratoconus; the surgery is safe and has an adequate biocompatibility. The procedure is adjustable and reversible and, most importantly, effective in improving unaided visual acuity (UAVA), best corrected visual acuity (BCVA). Aim of the Work: To compare the efficacy of MyoRing versus Ferrara ring using femtosecond laser for treatment of keratoconus as regards the visual outcome, refractive changes, keratometery reading (K-max), proper depth tilt and haze by anterior segment OCT and complications. Patients and Methods: This study included forty eyes of patients with keratoconus. They were divided into two groups. Group (A) included twenty eyes of patients with keratoconus subjected to femtosecond laser assisted MyoRing implantation, while Group (B) included twenty eyes of patients with keratoconus subjected to femtosecond laser assisted Ferrara ring implantation. Results: In group (A) MyoRing all patients showed improvement in UAVA, BCVA, refraction and K-max except 4 patients (20%) who showed no visual improvement despite the refractive and topographic improvement. Using the anterior segment OCT in interpretation of visual, refractive and topographic findings showed that those 4 patients had their MyoRings implanted at shallower depth with presence of intracorneal ring tilt. In group (B) Ferrara ring all patients showed improvement in UAVA, BCVA, refraction and K-max except 2 patients (10%) who showed no visual improvement despite the refractive and topographic improvement. Using the anterior segment OCT in interpretation of visual, refractive and topographic findings showed that those 2 patients had their Ferrara rings implanted at shallower depth with presence of intracorneal ring tilt. Conclusion: In comparison between two rings, there were no differences in different parameters except that the Ferrara ring showed more improvement in BCVA and spherical component. Using the anterior segment OCT in assessment of implanted rings, helped us to explain the non-improvement in visual outcomes despite the refractive and topographic improvements.

Intrastromal Corneal Ring Segments in Children with Keratoconus

ABSTRACT Purpose To evaluate the long-term follow-up of Ferrara intrastromal corneal ring segments (ICRSs) (Ferrara Ophthalmics, Belo Horizonte, Brazil) implantation for the management of keratoconus in children. Study design Paulo Ferrara Eye Clinic, Belo Horizonte, Minas Gerais, Brazil. Materials and methods A total of 58 eyes of 37 children with keratoconus were included. One or two ring segments were inserted into the cornea, embracing the keratoconus area. Statistical analysis included preoperative and postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), asphericity, pachymetry, and keratometry. Results Ferrara ICRS implantation significantly improved the mean UDVA and CDVA. Corneal tomography (Pentacam®) showed corneal flattening in all eyes implanted with the Ferrara ring. The mean K decreased, and the corneal asphericity and pachymetry increased in all cases. Conclusion The Ferrara ICRS improved all parameters after 2 years of implantation in children with keratoconus. There was significant corneal flattening after ring implantation with improvement of the UDVA and the CDVA. All studied parameters remained stable over time. How to cite this article Ferrara G, Ferrara P, Torquetti L. Intrastromal Corneal Ring Segments in Children with Keratoconus. Int J Kerat Ect Cor Dis 2017;6(2):45-48.

Intrastromal corneal ring segments implantation in patients with keratoconus: 10-year follow-up.

To evaluate the long-term safety and efficacy of Ferrara intrastromal corneal ring segments (ICRS) (Ferrara Ring; AJL, Boecillo, Spain) in patients with keratoconus. The chart records of 36 eyes of 30 patients with keratoconus implanted with ICRS, operated on between July 1996 and January 2002, were retrospectively reviewed. The following parameters were studied: uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), keratometry (K), and central corneal thickness. The outcomes were evaluated at 5 and 10 years after ICRS implantation. The mean UDVA (logMAR) improved from 1.01 ± 0.28 (20/200 Snellen) to 0.71 ± 0.38 (20/100 Snellen) at 5 years (P < .05) and 0.67 ± 0.25 (20/90 Snellen) at 10 years (P = .735). The mean CDVA (logMAR) improved from 0.45 ± 0.45 (20/55 Snellen) to 0.24 ± 0.19 (20/35 Snellen) at 5 years (P < .05) and 0.29 ± 0.09 (20/38 Snellen) at 10 years (P = .292). The mean maximum K value decreased from 54.99 ± 6.33 to 50.58 ± 5.11 D at 5 years (P < .05) and 50.65 ± 5.17 D at 10 years (P = .854). The mean minimum K value decreased from 48.85 ± 5.70 to 46.90 ± 5.08 D at 5 years (P < .05) and 47.12 ± 4.22 D at 10 years (P = .945). The central corneal thickness decreased from 457.42 ± 58.21 to 421.34 ± 74.12 μm at 5 years (P = .039) and 434.32 ± 77.65 μm at 10 years (P = .427). Intrastromal corneal ring segments can effectively improve UDVA and CDVA 10 years after implantation in patients with keratoconus.

Intra-Stromal Corneal Ring Segments

Intra-stromal corneal ring segments (ICRS) are a new modality in the treatment of corneal ectactic disorders like keratoconus, post lasik ectasia and pellucid marginal degeneration. ICRS is a minimally invasive technique wherein the central optical zone is not disturbed with long term convenient refractive correction. Two brands of ICRS segments are popular commercially, Intacs (Additions Technology Inc) and Ferrara Rings. ICRS reduces the sphere, cylinder and the spherical equivalent in keratoconus.

Ferrara ring’s effects on corneal asphericity in keratoconus treatment

AbstractPurpose In keratoconus treatment, Ferrera® rings nomogram integrates the Q factor defining corneal asphericity. Our study deals with the effect of the implantation of Ferrerra rings on the Q factorMethods This retrospective and monocentric study involves forty eyes of thirty‐one patients suffering from keratoconus implanted with Ferrara® rings, with an uncorrected visual activity (UCVA), a best spectacle‐corrected visual acuity (BSCVA) and a videokerato‐topography, before and six months after surgery. The items followed are the UCVA, the BSCA, the average (Kmean) and maximum keratometry (Kmax) and the Q factor in the central 20° (Q20) and 40° (Q40). The analyse of the visual acuity (more or less than a line) enables to differentiate two groups of “good” and “bad” responders. The statistical tests are a Wilcoxon signed rank for pre and post operative comparisons, a Wilcoxon‐Mann Whithey for group comparisons, and a Spearsman for correlations.Results The average age of patients is 32,8 years with 83,1% of male gender. Twelve eyes were implanted with two rings and twenty‐eight with one. We find an average gain of 3.6 lines for UCVA, 1.1 lines for BSCVA and a decrease in Kmean of 1,4 dioptry. Q20 and Q40 are meaningly improved after surgery, but there is no significant difference between the studied groups. Lastly, before surgery, BSCVA is correlated to Q20, and Kmax to Q40. After surgery, UCVA is correlated to Q20 and Kmax to Q20. But the Kmax variation and the UCVA or BSCVA gains are not correlated.Conclusion Including the Q factor in the nomogram establishing ring’s choice improves the keratometric field but not the visual outcome.

The Influence of Corneal Volume in Surgical Planning: Insights for a New Parameter for the Ferrara Ring Nomogram

ABSTRACT Purpose To evaluate the corneal volume (CV) before and after Ferrara intrastromal corneal ring segments (ICRS) implantation and its influence in clinical outcomes in keratoconus patients. Materials and methods A total of 77 eyes of 42 keratoconus patients consecutively implanted with the Ferrara ICRS were evaluated with a Pentacam (Oculus Optikgerate GmbH). The following parameters were obtained: Anterior corneal asphericity (Q), CV and thinnest corneal thickness (TCT). The inter-relation between Q and CV was evaluated. Results In patients with CV inside two standard deviation (SD: 53.51-60.65) of the mean CV, the postoperative asphericity values roughly agreed with expected asphericity values. In patients with CV outside two SD intervals (&lt;53.51 and &gt;60.65) of the mean CV, the postoperative asphericity values did not agreed with expected asphericity values. Corneas with high volumes (&gt;60.65) had less change of asphericity than corneas with low volumes. Conclusion The CV is a new parameter, to be better studied, as it seems to be important in ICRS selection. Corneas with high volumes may require more tissue to get flattened and properly reshaped. How to cite this article Torquetti L, Ferrara G, Dias WG, Ferrara P. The Influence of Corneal Volume in Surgical Planning: Insights for a New Parameter for the Ferrara Ring Nomogram. Int J Kerat Ect Cor Dis 2013;2(1):12-15.

Treatment of visual problems after intracorneal ring implantation

PurposeTo report the effect of wavefront-guided photorefractive keratectomy and corneal collagen cross-linking (CXL) on visual problems after Ferrara ring segment placement.Materials and methodsA 32-year-old male patient was treated with a Ferrara ring segment for keratoconus. One year later, the ring was removed due to severe glare complaints. After 6 months, wavefront-guided photorefractive keratectomy and CXL were applied simultaneously to correct high order aberration and refractive error.ResultsSix months after the wavefront-guided photorefractive keratectomy and CXL, the uncorrected distance visual acuity was 20/25, and there was a 30% decrease in coma aberrations. The glare complaint regressed.ConclusionWavefront-guided surface ablation and CXL may reduce high order aberrations and glare complaints after intrastromal corneal ring implantation.

Ferrara ring segments implantation for treating keratoconus.

To investigate the efficacy of Ferrara rings (FR) implantation in the treatment of keratoconus. 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. 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). 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.

Quantitative OCT-based corneal topography in keratoconus with intracorneal ring segments

Custom high-resolution high-speed anterior segment spectral domain Optical Coherence Tomography (OCT) was used to characterize three-dimensionally (3-D) corneal topography in keratoconus before and after implantation of intracorneal ring segments (ICRS). Previously described acquisition protocols were followed to minimize the impact of the motions of the eye. The collected set of images was corrected from distortions: fan (scanning) and optical (refraction). Custom algorithms were developed for automatic detection and classification of volumes in the anterior segment of the eye, in particular for the detection and classification of the implanted ICRS. Surfaces were automatically detected for quantitative analysis of the corneal elevation maps (fitted by biconicoids and Zernike polynomials) and pachymetry. Automatic tools were developed for the estimation of the 3-D positioning of the ICRS. The pupil center reference was estimated from the segmented iris volume. The developed algorithms are illustrated in a keratoconic eye (grade III) pre- and 30 days post-operatively after implantation of two triangular-section, 0.3-mm thick Ferrara ring segments. Quantitative corneal topographies reveal that the ICRS produced a flattening of the anterior surface, a steepening of the posterior surface, meridional differences in the changes in curvature and asphericity, and increased symmetry of the anterior topography. Optical distortion correction through the ICRS (of a different refractive index from the cornea) allowed accurate pachymetric estimates, which showed increased thickness in the ectatic area as well as in peripheral corneal areas. Automatic tools allowed estimation of the depth of the implanted ICRS ring, as well as its rotation with respect to the pupil plane. Anterior segment sOCT provided with fan and optical distortion correction and analysis tools is an excellent instrument for evaluating and monitoring keratoconic eyes and for the quantification of the changes produced by ICRS treatment.

Implante de segmentos de anel estromal em ceratocone: resultados e correlações com a biomecânica corneana pré-operatória

OBJETIVO: Verificar os resultados da cirurgia de implante de segmentos de anel estromal para ceratocone e as possiveis correlacoes existentes entre o resultado cirurgico e o estado biomecânico da cornea no pre-operatorio. METODOS: Dezenove olhos de 19 pacientes com ceratocone foram avaliados antes e 12 meses apos a cirurgia de implante de segmento anel estromal. O implante de um ou dois segmentos de anel de Ferrara foi realizado de acordo com o nomograma, considerando-se espessura da cornea, padrao topografico da ectasia e o astigmatismo. O teste de Wilcoxon signed rank foi realizado para verificar diferencas entre a acuidade visual (logMAR) corrigida com oculos antes da cirurgia (AVccPre) e a obtida sem correcao (AVscPos) e com correcao (AVccPos) apos a cirurgia, bem como entre os valores pre e pos-operatorios de variaveis tomograficas medidas com o Pentacam e variaveis biomecânicas da cornea medidas com o ORA (ocular response analyzer). As diferencas absolutas antes e apos a cirurgia (valores delta - Δ) das variaveis com diferencas significantes foram calculadas. Os valores Δ foram correlacionados com as medidas do ORA no pre-operatorio por meio dos testes de Pearson ou de Spaerman, de acordo com a distribuicao das variaveis ser normal ou nao (teste de Kolmogorov-Smirnov). RESULTADOS: Observou-se melhora significante na AVcc, bem como na AVscPos em comparacao com a AVccPre (teste de Wilcoxon, p 0,05). Os parâmetros do ORA derivados das pressoes de aplanamento: histerese da cornea (corneal hysteresis - CH), fator de resistencia da cornea (corneal resistance factor - CRF) e as medidas da pressao ocular (IOPg e IOPcc) nao apresentaram correlacoes significantes com os parâmetros delta (Δ). Quinze das 38 variaveis biomecânicas derivadas do sinal de reflexo da cornea do ORA apresentaram correlacao significante com pelo um parâmetro Δ, destacando-se as correlacoes entre o ΔKMax com aindex e path1 (teste de Pearson, p<0,05; r=-0,56 e 0,56 respectivamente) e entre o ΔAVccPre-AVscPos e aindex (teste de Pearson, p<0,05; r=0,48). A variavel que teve maior numero de correlacoes significantes foi w21, que se correlacionou negativamente com ΔK2, ΔK1, ΔCKI e ΔKMax (teste de Spearman, p<0,05; r=-0,56; -0,55; -0,51 e -0,47) respectivamente. CONCLUSAO: Existe melhora significante da acuidade visual e de parâmetros ceratometricos apos cirurgia de implante de segmentos de anel de Ferrara para ceratocone. A melhora de diversos destes parâmetros com a cirurgia foi significativamente correlacionada com caracteristicas biomecânicas derivadas do sinal do reflexo da cornea do ORA no pre-operatorio. Um estado biomecânico pre-operatorio mais fraco ou menos resistente foi significativamente relacionado com um maior beneficio clinico da cirurgia. Analises com associacoes multiplas (multivariadas) sao necessarias, incluindo parâmetros tomograficos da cornea e de aberrometria total do pre-operatorio. Tais informacoes abrem novos horizontes para a selecao de pacientes e o planejamento de cirurgia de implante de segmentos de anel para ceratocone.

Facteurs prédictifs de succès des anneaux intracornéens de Ferrara dans le kératocône

To define predictive factors after manual implantation of intrastromal corneal ring segments (Ferrara ring) for the management of keratoconus. Twenty-five eyes of 25 patients with keratoconus were implanted with Ferrara intracorneal ring segments using a mechanical procedure. We measured corneal ring implantation depth, best spectacle-corrected visual acuity (BSCVA), as well as refractive and keratometric outcomes. Patients were separated into two groups according to the gain of at least two lines of BSCVA ("good response") or the gain of only one line of BSCVA, no change, or the loss of lines of BSCVA ("poor response"). After a 6-month follow-up, 41% patients experienced a gain of at least two lines of BSCVA, 31.8% a gain of only one line, 13.6% no change, and 13.6% a loss of BSCVA. The sphere reduced from 4.39 to 2.34D (p<0.01), the cylinder from 4.19 to 2.77D (p<0.01), and the mean keratometry from 51.44 to 48.74D (p<0.02). As successful predictive factors, we found the asymmetry of keratoconus (p<0.01) in relation to the steepest meridian and patients implanted with a single ring (p<0.02). Defining preoperative successful predictive factors for Ferrara intracorneal ring segments is essential to enhance postoperative outcomes.

Treatment strategies for corneal ectasia

To review the most recent management strategies for corneal ectasia after keratorefractive surgery. Management options for postoperative ectasia include conservative management with various types of contact lenses such as rigid gas permeable lenses, custom wave front-guided soft contact lenses, hybrid lenses and tandem soft contact lens-rigid gas permeable lenses. Minimally invasive surgical options including corneal ring segment implantation with Intacs, KeraRings or Ferrara rings have shown to have good results in the initial period after insertion. However, there appears to be some evidence that this initial effect may regress with time. Collagen cross-linking is also minimally invasive and has been documented to stop the progression of ectasia and in some cases may cause regression. Recently, techniques combining collagen cross-linking with intracorneal ring segments or with topography-guided excimer laser treatments have shown to have promising results. Early management of ectasia is essential to prevent its progression and to preserve visual potential. There are several management options that are available that may be used to reduce the need for corneal transplantation for these patients.

Microbial Keratitis After Intrastromal Corneal Ring Segment Implantation

To evaluate the incidence of acute microbial keratitis after intrastromal corneal ring segment implantation and to investigate whether microbial keratitis is related to the intrastromal corneal ring type or surgical technique. Intrastromal corneal ring segments were implanted in 212 eyes of 149 patients. Two different types of intrastromal corneal ring segments were used during the study, Intacs and Ferrara rings, and two surgical techniques were used for intrastromal corneal ring segment implantation, manual and femtosecond laser. One hundred thirty-four eyes (63.2%) underwent Intacs implantation and 78 (36.8%) eyes received Ferrara rings. Corneal tunnels were created using the manual technique in 119 (56.1%) eyes and by femtosecond laser in 93 (43.9%) eyes. Three cases (1.4%) of acute microbial keratitis were clinically identified. Cultures were positive in 2 eyes and negative in 1 eye, and polymerase chain reaction was positive in all 3 cases. The microorganisms isolated from cultures were Streptococcus mitis and Staphylococcus aureus. In 2 cases, the femtosecond laser technique was used (1 eye Intacs, 1 eye Ferrara), and in 1 case, the manual technique was used (Intacs). No statistically significant difference was noted between techniques (P=.582) or segment type (P=1.000). In all cases, intrastromal corneal ring segments were explanted and intensive topical antibiotics were used with clinical success. Acute microbial keratitis incidence after intrastromal corneal ring segment implantation was 1.4%. Gram-positive cocci were the organisms isolated more frequently. Proper management of this condition requires intrastromal corneal ring segment explantation and intensive topical antibiotics.

Intracorneal ring segments in ectatic corneal disease – a review

The purpose of this review is to collect and summarize all the scientific literature regarding the use of intracorneal ring segments (ICRS) in corneal ectatic disease. These implants, initially designed to correct myopia in normal eyes, are implanted in the deep corneal stroma with the aim of achieving modifications to the corneal curvature and subsequently refractive adjustments. Colin et al. in 2000 were the first to report the efficacy of these implants in reducing the refractive error and corneal steepening in keratoconus eyes. Two main types of ICRS have been developed and used for the treatment of ectatic corneal disease, different in profile and diameter of implantation: Intacs and Ferrara rings. Successful outcomes have been reported by several authors with these implants in keratoconic eyes using different nomograms. Besides keratoconus, ICRS have been also used successfully for the management of pellucid marginal degeneration and post-laser in situ keratomileusis corneal ectasia. The implantation procedure may be performed today by two surgical techniques to create the corneal channels where implants are inserted: mechanical dissection using a manual semicircular dissector (mechanical-assisted) and photodisruption of lamellar tissue using the femtosecond laser technology (femtosecond-assisted). With both techniques, visual, refractive and topographic improvements have been observed, although higher incidence of intraoperative and postoperative complications have been reported with the mechanical procedure according to the evidence found in the peer-reviewed literature. ICRS technology is a promising therapeutic option in corneal ectatic disease, avoiding corneal graft and allowing a visual and refractive rehabilitation.

Corneal Collagen Cross Linking (CXL): A Review

Treatments for conditions affecting the biomechanical strength of the cornea, until now, have been limited to treatment of the consequences of progressive weakness of the cornea such as inserts (Intacs or Ferrara rings) and corneal grafting (Deep anterior Lamellar or Penetrating Keratoplasty). Neither addresses the basic defect within the cornea. Corneal collagen crosslinking (CXL) is a treatment designed to increase the rigidity and structural integrity of the cornea, preventing progression to end-stage disease. Keratoconus is a common condition, affecting 1 in 2000 of the population. It typically affects the young, presenting in adolescence with distorted vision. It is a noninflammatory, degenerative disorder of the cornea, characterized by stromal thinning and conical ectasia, resulting in irregular astigmatism and associated visual loss. It is usually an isolated condition; however, commonly recognized associations include Down syndrome, Leber congenital amaurosis, and connective tissue disorders. Atopy, eye rubbing, and hard contact lenses have also been reported to be highly associated with this disorder, and 6% to 8% of reported cases have a positive family history or show evidence of familial transmission. Recent biochemical assays and immunohistological studies of corneas with keratoconus suggest that the loss of corneal stroma after digestion by proteolytic enzymes could be caused by increased levels of proteases (matrix metalloproteinase) and

INTACS for Keratoconus

BACKGROUND INTACS are two, arc like, PMMA segments which were designed to be surgically inserted into the deep corneal stroma to flatten the central cornea. Their original application was for the refractive correction of mild myopia (−1 to −3D). However, because of the superior accuracy and familiarity with the excimer laser by refractive surgeons, they are rarely used for this indication, except in patients with forme fruste keratoconus or extremely thin corneas with less than 3D of Myopia (1,2). Dr. Joseph Colin in France first conceived of the concept of using INTACS to treat patients with keratoconus and published his first report on the safety and efficacy for this indication in 2001(3). At 1 year, all 10 patients he operated became contact lens tolerant and demonstrated an improvement in both uncorrected and best-corrected acuity (4). Since his pioneering work, corneal surgeons throughout the word have adopted this technology to treat patients with mild to moderate keratoconus who are contact lens intolerant and/or who desire a modest improvement in uncorrected and best-corrected visual acuity (5-14). In the United States 0.25mm, 0.275mm, 0.30mm, 0.325mm and 0.35mm segments are available for use. They are approved in the United States by the FDA under an Human Devise Exemption for compassionate therapeutic use. Outside of the United States .40mm and 0.45mm sized segments are also available. Competitive devices the Ferrara ring and the Keraring are also sold and marketed outside of the United States since they do not have FDA approval in the USA. The main difference between these two devices is that with INTACS the optical zone is approximately 7mm while the Ferrara and Kerarings have an optical zone of the order of 4.5 to 5mm. Recently Intacs SK was introduced outside of the United States. They have an optical zone of 6 mm and have a round design to minimize glare. They may be used to correct larger myopic and astigmatic refractive errors than INTACS because of their design and closer proximity to the visual axis(15)