Corneal infections after implantation of intracorneal ring segments

PURPOSE: To report risk factors, clinical course, and outcome in patients with infectious keratitis following implantation of intracorneal ring segments (ICRS). METHODS: The records of 8 patients with culture-proven infectious keratitis after ICRS (Ferrara or Intacs) implantation were retrospectively reviewed. Age, gender, corneal findings, ocular abnormalities, the condition that led to ICRS implantation, immediate prior use of a contact lens, elapsed time between implantation and the onset of symptoms, previous medications, and systemic disorders were noted. RESULTS: Culture-positive infectious keratitis developed in 7 eyes of 7 patients (2 men and 5 women) with a mean age of 35 years who underwent Ferrara implantation for the treatment of keratoconus and in a 29-year-old man who underwent Intacs implantation for correction of low myopia. Contact lens use, diabetes, and trauma were factors possibly associated with the risk of infection in three cases. Microorganisms, identified in all cases, included Staphylococcus aureus, Streptococcus viridans, Streptococcus pneumoniae, Pseudomonas sp, Nocardia sp, Klebsiella sp, and Paecylomices sp. Onset of symptoms of infection varied from less than 1 week to 22 months postoperatively, depending on the infecting organism. CONCLUSIONS: Infectious keratitis following ICRS implantation is a sight-threatening complication for which early recognition and rapid institution of appropriate treatment may result in a better visual outcome.     

Microbial keratitis after INTACS implantation with loose suture

PURPOSE: To report a case of rapidly progressive infectious keratitis after INTACS implantation for keratoconus. METHODS: A 32-year-old man presented with pain and decreased vision in the right eye of 2 days' duration. Right eye visual acuity was 20/800. He had undergone bilateral INTACS implantation 40 days prior for treatment of keratoconus. RESULTS: Slit-lamp examination revealed corneal ulceration and loose suture. The corneal ulcer progressed despite aggressive therapy, and the patient underwent penetrating keratoplasty 48 hours after admission. The culture from corneal scraping and corneal button was positive for Staphylococcus aureus. CONCLUSIONS: Infectious keratitis is a rare but devastating complication of INTACS implantation for treatment of keratoconus. Meticulous wound closure is necessary to reduce the risk of infection, especially in eyes with irregular corneal contour and variable corneal thickness.     

Late bacterial keratitis after intracorneal ring segments (Ferrara ring) insertion for keratoconus

PURPOSE: To report a case of late bacterial keratitis after intrastromal corneal ring segments (ICRSs; Ferrara ring; Ferrara Ophthalmics, Belo Horizonte, Brazil). METHODS: Review the clinical findings in a 42-year-old woman with bilateral keratoconus who underwent implantation of Ferrara ring segments in her left eye and 4 months later presented with corneal infiltrates and hypopyon. Bacterial staining, culture, and antibiotic sensitivities were done. Medical treatment and rings explantation were performed. RESULTS: The cultures revealed growth of vancomycin-oxacillin sensible coagulase-positive Staphylococcus aureus. Treatment with topical moxifloxacin, topical imipenem, and systemic intravenous and topical vancomycin was kept for two weeks. Corneal inflammation and hypopyon resolved, leaving a minimal residual leucoma. CONCLUSIONS: Infectious keratitis is an uncommon complication of ICRS and it may be late in presentation, even months after implantation. Importance of patient education about alarm symptoms and the need for long-term close postoperative follow-up cannot be underestimated. If a change in surgical technique, i.e., suturing the incision, has an influence in this complication's incidence, it will require further studies.     

Clinical effectiveness of intrastromal corneal ring segments among keratoconus patients

AIM: To evaluate the clinical effectiveness of intrastromal corneal ring segments (ICRS) among the patients suffering from keratoconus. METHODS: A retrospective and non-comparative interventional design had been utilized on the basis of postoperative follow-up among 56 keratoconus patients. Visual acuity was significantly assessed during complete ophthalmic examination of the patients. The femtosecond laser had been used to create the corneal tunnels in 15 eyes; whereas, the corneal tunnels were created in 72 eyes mechanically. RESULTS: The ranges and standard deviations had been used to obtain results. It had been revealed through ophthalmic assessment that the mean preoperative uncorrected visual acuity observed was 1.38±0.37 logarithm of Minimal Angle of Resolution. Moreover, a significant improvement was observed postoperatively in visual acuity by 0.58±0.32 during the 4th month. The improvement was also witnessed in the 16th month by 0.48±0.30. CONCLUSION: The implantation of ICRS is an efficient and effective surgical intervention for the treatment of keratoconus. Thus, identified intervention seems to be associated with appropriate visual outcomes and safety after the development of femtosecond as well as mechanical tunnels.     

圆锥角膜的治疗进展

本文通过对圆锥角膜治疗方法的综述,为临床医生选择合适的治疗方法做出参考。通过数据库对“圆锥角膜”“隐形眼镜”“角膜胶原交联”“Intacs(角膜环)”“角膜成形术”“基因治疗”“不规则散光”等关键词进行搜索,并根据相关文献对圆锥角膜的治疗方法进行综述。眼镜和隐形眼镜可用于圆锥角膜早期,而疾病晚期时可采用前弹力层移植术、穿透性角膜成形术(PK)和深层前板层角膜成形术(DALK)、传导性角膜成形术和基因治疗。此外,角膜胶原交联可以阻止圆锥角膜进展,角膜基质环植入术(ICRS)通过使变形角膜变平,减少屈光不正以达到治疗目的。总得来说,眼科诊断技术和治疗方法的发展可以减缓圆锥角膜进展,从而减少晚期角膜圆锥患者对角膜移植的需要。选择恰当的圆锥角膜治疗方案可以帮助患者改善视力和预防失明。     

Keratitis after Implantation of Intrastromal Corneal Rings with Spontaneous Extrusion of the Segment

Purpose

To report a case of bacterial keratitis in a patient with a history of intrastromal corneal ring segments (INTACS®) implantation to correct keratoconus.

Methods

The patient''s history, clinical presentation, pathological analysis and therapeutic management were reviewed.

Results

A 36-year-old-man was referred to our department due to decreased vision and intense pain in his left eye, 40 days after INTACS® implantation for keratoconus. Slit-lamp examination revealed epithelial defects and stromal infiltrates in the lower channel without evidence of the inferior ring. The anterior chamber also showed a significant fibrin reaction to hypopyon. A low-tension suture was removed at the site of the incision. Microbiological study of the conjunctival swab was positive for Staphylococcus epidermidis, but the corneal culture was sterile. The patient was treated with topical fortified and systemic antibiotics. The infection slowly resolved, leaving opacity at the inferior segment site.

Conclusions

Infectious keratitis following INTACS implantation is an infrequent complication that can have important consequences without suitable and early therapeutic management.Key Words: INTACS®, Intrastromal rings, Keratitis, Segment extrusion     

圆锥角膜基质环植入术的研究进展

角膜基质环植入术(ICRS)是一种用于治疗轻中度圆锥角膜的手术方法。ICRS是通过植入基质环,使中央角膜扁平化,弧长缩短,角膜曲率半径增大,屈光力降低,从而改善角膜前突导致的轴性近视眼与不规则散光。ICRS具有微创性、安全性、有效性、可逆性且并发症少等优点,其中长期疗效较佳。本文中笔者就ICRS的发展史、适应症、手术方法、手术疗效的影响因素、术后处理及疗效的评估等方面进行阐述。     

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.     

Intrastromal corneal ring segments for management of keratoconus

Keratoconus is a progressive corneal ectasia, which can be managed both by conservative measures like glasses or contact lenses in non-progressive cases or surgical procedures like collagen crosslinking (CXL) with or without adjuvant measures like intrastromal corneal rings segments (ICRS) or topography guided ablation. Various kinds of ICRS are available to the surgeon, but it is most essential to be able to plan the implantation of the ring to optimize outcomes.

Aims:

The aim of this study is to evaluate the visual outcome and progression in patients of keratoconus implanted with ICRS.

Materials and Methods:

Two different types of ICRS-Intacs (Addition Technology) and Kerarings (Mediphacos Inc.) were implanted in 2 different cohorts of patients and were followed-up to evaluate the outcome of the procedure. All patients underwent a complete ocular examination including best spectacle corrected visual acuity, slit lamp examination fundus examination, corneal topography and pachymetry. The ICRS implantation is done with CXL to stop the progression of the disease. Improvement in uncorrected visual acuity (UCVA), best spectacle corrected visual acuity and topographic changes were analyzed.

Results:

A significant improvement in keratometry and vision was seen in both groups.

Conclusion:

ICRS have been found to reduce corneal irregularity and flatten keratometry with improvement in UCVA and best corrected visual acuity.     

Influence of intrastromal corneal ring segment implantation on corneal biomechanical parameters in keratoconic eyes

Purpose  

To assess the influence of intrastromal corneal ring segment (ICRS) implantation on corneal biomechanics in patients with keratoconus.     

Clinical and histological studies on the intrastromal corneal ring segments (ICRS(R), Intacs(R))

Intrastromal corneal ring segments (ICRS(R), Intacs(R)) are corneal inlays made of PMMA with an arc length of 150 degrees for the correction of low to moderate myopia. This additive and potentially reversible method has recently been developed to clinical usefulness during the last few years. Besides the historical development und the results of the US FDA studies, we focus on the results of the European experience with this technique. For the first time, long-time follow-up results (5 years from a single surgical center) are presented. Morphological changes after implantation of Intacs(R) were investigated in a series of patients by confocal microscopy. Weeks and months after implantation "lamellar channel deposits" regularly appear around the segments. This material consists of intracellular lipids (cholesterol ester, triglyceride and unesterified cholesterol), as we could show in new histological studies on rabbit eyes. New developments of this technique include short arc length segments (130 degrees ) for the correction of myopia concurrent with astigmatism and radially placed corneal inlays (Intrastromal Corneal Segments, ICS(R)) for the correction of hyperopia. In recent years, Intacs(R) have also been implanted in eyes with keratoconus and keratectasia after LASIK. These early results seem to indicate that in certain cases of early keratoconus, these implants can indeed improve corneal geometry and vision. Even in cases of regression or undercorrection after LASIK (with thin corneas), Intacs(R) seem to give promising results in selected cases. Although Intacs(R) do give comparable results regarding both safety and efficacy when compared with PRK and LASIK, this technology has not yet been widely accepted among refractive surgeons. Whether Intacs(R) will play a greater role in routine refractive surgery in the future or will just remain a special device for the correction of keratectasia, keratoconus or regression after LASIK cannot yet be decided with certainty.     

Mycotic keratitis in non-steroid exposed vernal keratoconjunctivitis.

PURPOSE: To report a patient with vernal keratoconjunctivitis who developed mycotic keratitis in absence of known risk factors. METHODS: A 17-year-old male suffering from vernal keratoconjunctivitis presented with infective keratitis. The patient had been treated in the past with topical antihistaminics and vasoconstrictors. The patient had not been exposed to topical steroids in 2 years of follow-up. He did not have dry eye or corneal micro or macroerosions prior to the development of infective keratitis. Corneal scrapings were obtained and subjected to KOH wet mount smear, calcofluor and Grams stain as well as bacterial culture sensitivity and fungal culture. RESULTS: Clinical diagnosis of mycotic keratitis in association with vernal conjunctivitis was supported by microbiological investigations. KOH wet mount and calcofluor staining showed presence of filamentous septate hyphae while fungal culture showed growth of aspergillus fumigatus. Antifungal therapy was initiated in the form of topical natamycin 5% suspension to which the patient responded and recovered 6/6 final visual acuity. CONCLUSION: The authors wish to conclude that patients suffering from vernal keratoconjunctivitis, even in the absence of corneal involvement, steroid exposure and trauma, may be at increased risk of developing keratomycosis.     

Long-term follow up of intracorneal ring segment implantation in 932 keratoconus eyes

PurposeTo evaluate the progression of keratoconus in 932 eyes of 659 patients through visual, refractive and topographic data after intracorneal ring segment (ICRS) implantation.MethodsRetrospective review of 659 patients who underwent ICRS (Intacs®) implantation for keratoconus between September 1997 and November 2017. Demographics, preoperative and postoperative uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) in LogMAR, corneal topography parameters (thinnest pachymetry, Kmax), central corneal pachymetry and total follow-up time were evaluated. Statistical analysis was performed using IBM SPSS Statistics 24.0 for windows.ResultsNine hundred and thirty-two eyes of 659 patients, with a mean age of 30.41 years (range 11–76 years), were evaluated. Mean total follow up time was 3.02 years. Forty-one eyes had a total follow up of over 10 years. Both UCVA and BCVA improved significantly after ICRS implantation (P < 0.01). Only 18 eyes (2.66% of eyes of patients under 35 years of age) were found to have progression of keratoconus based on postoperative topographic data (Mean age 23.00 years, 55.6% female, total follow-up 2 to 10 years)ConclusionICRS implantation showed long-term improvement and stability in visual and topographic results in a large case series of patients with keratoconus. Only a minimal rate of progression was detected in young patients. However, further prospective studies need to be conducted to better define predictability of postoperative visual outcomes and progression.     

Intrastromal corneal ring implantation for the correction of myopia: 12-month follow-up

PURPOSE: To evaluate the efficacy, predictability, and stability of refraction obtained after intrastromal corneal ring segment (ICRS) implantation for low to moderate myopia. SETTING: Single-center clinical practice. METHODS: In this prospective 2-surgeon study, 9 patients (15 eyes) with low to moderate myopia were recruited to receive ICRS implants. RESULTS: At 1 day, 10 of the 15 eyes had an uncorrected visual acuity (UCVA) of 20/40 or better. At 12 months, all eyes had this UCVA and 66.6% had 20/25 or better. The mean manifest refraction stabilized after the first week at <-0.5 diopter (D). At 12 months, all eyes were within +/-1.0 D of the intended manifest refraction; 67% were within +/-0.5 D. Sixty percent of eyes had no change from the preoperative best corrected visual acuity; 13.3% improved by 1 line, and 26.6% lost 1 line. The postoperative complications included lamellar channel deposits (n = 12), ICRS dislocation (n = 2), corneal infiltrates (n = 2), bleeding in the positioning ring hole (n = 1), 0.3 mm segment decentration (n = 1), and prolonged wound healing (n = 1). CONCLUSIONS: Intrastromal corneal ring segment implantation for the correction of low to moderate myopia afforded good visual recovery and efficacy similar to that with laser in situ keratomileusis and superior to that with photorefractive keratectomy. However, light or blunt trauma and insufficient hygiene can have serious consequences and there is the potential for induced astigmatism. Corneal infiltrates can occur and must be treated immediately. The ring implantation technique is demanding. Advantages of ICRS implantation include rapid and stable visual recovery as well as reversibility.     

Aspergillus fumigatus keratitis with wreath pattern infiltrates.

PURPOSE: To report a case of Aspergillus fumigatus keratitis with clinical features simulating Nocardia keratitis and to highlight the utility of microbiologic investigation in the successful management of infectious keratitis. METHOD: Case report. RESULTS: A 62-year-old man presented with complaints of pain, redness, and watering of 10 days' duration in his right eye. Direct microscopic observation of smears of corneal scrapings revealed a fungal etiology. The patient was treated with 5% natamycin eye drops and 1% atropine sulphate eye drops and was advised to visit the hospital for observation. During his visit to the hospital on day 10 after medication, the eye demonstrated a wreath pattern corneal infiltrate that simulated Nocardia keratitis. The fungus grown from culture of corneal scraping was identified as A. fumigatus. CONCLUSION: This report highlights the significance of subjecting corneal scrapings from suspected cases of infectious keratitis to microbiologic evaluation and emphasizes the fact that a complete microbiologic work-up helps in establishing a definitive etiologic diagnosis and initiating specific antimicrobial therapy.     

Ferrara intrastromal corneal rings for the correction of keratoconus

PURPOSE: To evaluate the safety and efficacy of Ferrara intrastromal corneal rings in the treatment of eyes with keratoconus without central corneal scarring. SETTING: Vlemma Eye Institute, Athens, Greece. METHODS: Twenty-six patients with bilateral keratoconus, clear central corneas, and contact lens intolerance participated in the study. Videokeratographic corneal topography and ultrasonic pachymetry were performed in all eyes to identify the cone area and to select the thickness of the segments to be implanted, respectively. Ferrara intrastromal corneal rings were implanted around the center of the cone in 1 eye of each patient. RESULTS: The minimum follow-up after ring implantation was 6 months. In 2 cases, the rings had to be removed early in the postoperative period because of superficial implantation in 1 patient and asymmetrical placement in the other. The rest of the operated eyes demonstrated a reduction in astigmatism and spherical correction and improved uncorrected visual acuity. No eye lost best corrected visual acuity. CONCLUSIONS: Ferrara intrastromal corneal rings reduced corneal steepening and normalized the central cornea in eyes with keratoconus. Ferrara ring implantation was a safe procedure that may be considered in patients who are unable to have other surgical techniques, particularly contact-lens-intolerant keratoconus patients whose only option is corneal transplantation.     

Spontaneous breakage of intracorneal ring segments (ICRS) 8 years after implantation

We present a case of spontaneous in situ breakage of intracorneal ring segments (ICRSs) 8?years after their implantation in a patient with keratoconus. The patient presented to our clinic with a red and painful right eye that had not improved despite topical steroids and antibiotics. The decision was made to explant the broken ICRSs from the cornea and send them for laboratory analyses, by which manufacturer defects were excluded. It is noteworthy that corneal curvature re-steepening was observed 4?months after ICRS removal despite the performance of crosslinking (CXL) 1?year prior to ICRS implantation.     

【In Press】 Etiology and failure analysis of anterior lamellar keratoplasty

AIM: To analyze indications and reasons for failure of anterior lamellar keratoplasty (ALK). METHODS: The clinical records were retrospectively reviewed. Main outcome measures: included indications for ALK and reasons for failure of ALK. RESULTS: A total of 434 patients (462 eyes) were treated with ALK at Qindao Eye Hospital, Shandong Eye Institute from June 1, 2009 to May 31, 2016. The main indications were infectious keratitis (33.3%), keratoconus (23.6%), corneal dystrophy and degeneration(9.7%), Mooren''s ulcer(8.4%), corneal neoplasm(7.8%), viral keratitis(6.5%) and regrafting (3.7%). Fungal keratitis accounted for 73.4% in the infectious keratitis cases. ALKs were failed in 36 patients, with the major causes being recurrence of primary diseases (63.9%). The leading causes of graft failure was Mooren''s ulcer (36.1%), followed by infectious keratitis (30.6%). Recurrence of fungal keratitis accounted for 81.8% in the failed cases after ALK for infectious keratitis cases. CONCLUSION: Infectious keratitis and keratoconus are the main indications for ALK, of which fungal keratitis was the major cause of corneal infections. Recurrence of primary disease is the main reason of graft failure after ALK, in which the main primary diseases associated with graft failure are Mooren''s ulcer and fungal keratitis.     

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 April 2014. 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 from 0.82 to 0.31 (P<0.001); the mean BCVA improved from 0.42 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.     

Matrix metalloproteinases (MMP-8, MMP-9) and the tissue inhibitors of metalloproteinases (TIMP-1, TIMP-2) in patients with fungal keratitis

PURPOSE: To study the infiltrating cells and quantify the levels of matrix metalloproteinases (MMP-8, MMP-9) and tissue inhibitor of metalloproteinases (TIMP-1, TIMP-2) in the cornea, tear, and serum of patients with fungal keratitis. METHODS: Experimental study. Infected corneal tissue from 4 patients with fungal keratitis (group 1) scheduled to undergo therapeutic keratoplasty accounted for the histopathologic and cytospin smear analysis. Ten patients with fungal keratitis from group 2 served for the quantification of MMPs and TIMPs. Five patients with keratoconus undergoing penetrating keratoplasty and 5 cadaver corneas were chosen as controls for group 2. Corneal buttons obtained during keratoplasty, 15 to 20 microL of tears collected using the capillary flow method, and 3 mL of blood was obtained from patients with fungal keratitis and patients with keratoconus. Corneal button sections from group 1 were stained with hematoxylin and eosin and Grocott methenamine silver nitrate for the histopathologic studies and Giemsa staining for the cytospin smear analysis. Enzyme-linked immunosorbent assay was used for the quantification of total MMP-8, MMP-9, TIMP-1, and TIMP-2 in the corneal homogenates, tear, and serum samples of group 2. RESULTS: Corneal sections from group 1 revealed dense fungal filaments and a large proportion (91.4% +/- 38%) of polymorphonuclear leukocytes (PMNs). Significant elevation in the levels of MMP-8 and MMP-9 (P < 0.05) in the fungal keratitis corneas was observed in group 2 compared with the cadaver and keratoconus corneas. The ratio of MMP/TIMP was also higher in the fungal keratitis corneas. CONCLUSIONS: Infiltrating PMNs in the cornea of patients with fungal keratitis contributed to the increased activities of MMP-8 and MMP-9, thereby enhancing tissue destruction and derangement.