Intrastromal Corneal Ring Segments: Reversibility of Refractive Effect

Cataract surgery following refractive surgery: Principles to achieve optical success and patient satisfaction

A growing number of patients with prior refractive surgery are now presenting for cataract surgery. Surgeons face a number of unique challenges in this patient population that tends to be highly motivated to retain or regain functional uncorrected acuity postoperatively. Primary challenges include recognition of the specific type of prior surgery, use of appropriate intraocular lens (IOL) power calculation formulas, matching IOL style with spherical aberration profile, the recognition of corneal imaging patterns that are and are not compatible with toric and/or presbyopia-correcting lens implantation, and surgical technique modifications, which are particularly relevant in eyes with prior radial keratotomy or phakic IOL implantation. Despite advancements in IOL power formulae, corneal imaging, and IOL options that have improved our ability to achieve targeted postoperative refractive outcomes, accuracy and predictability remain inferior to eyes that undergo cataract surgery without a history of corneal refractive surgery. Thus, preoperative evaluation of patients who will and will not be candidates for postoperative refractive surgical enhancements is also paramount. We provide an overview of the specific challenges in this population and offer evidence-based strategies and considerations for optimizing surgical outcomes.

Morphological characterization and clinical effects of stromal alterations after intracorneal ring segment implantation in keratoconus

PURPOSE

To analyze the histological and (ultra)structural stromal tissue changes after femtosecond (Fs) laser-assisted intracorneal ring segment (ICRS) implantation and their refractive and topographic effects in patients with keratoconus.

METHODS

This monocentric retrospective case series included 15 consecutive patients with clinical peri-segmental lamellar channel deposits after treatment with Fs-ICRS implantation for keratoconus. The stromal changes were investigated using in vivo confocal microscopy. Two patients underwent a penetrating keratoplasty after the Fs-ICRS implantation; the explanted corneas were processed for histopathology and transmission electron microscopy (TEM). Refractive and topographic effects were investigated comparing the uncorrected (UDVA) and corrected (CDVA) distance visual acuity, spherical equivalent (SE), flat (K1), steep (K2), and steepest (Kmax) keratometry before and after detection of lamellar channel deposits.

RESULTS

In vivo confocal microscopy revealed diffuse linear and focal granular hyperreflective structures. Histologically, there was mild proliferation of fibroblasts and fibrosis. TEM demonstrated focal accumulations of degenerated keratocytes with cytoplasmic lipid inclusions. There were no significant changes for UDVA (Δ = 0.0 ± 0.2 logMAR; p = 0.67), CDVA (Δ = 0.0 ± 0.1 logMAR; p = 0.32), SE (Δ 0.1 ± 0.9 D; p = 0.22), K1 (Δ = 0.3 ± 1.0 D; p = 0.28), K2 (Δ = 0.1 ± 0.9 D; p = 0.51), and Kmax (Δ = 0.3 ± 1.5 D; p = 0.17).

CONCLUSIONS

Two types of structural stromal changes were identified: (1) diffuse peri-segmental fibrosis and (2) lamellar channel deposits. These structural changes showed no evidence of a relevant refractive or topographic effect.

Long-term results of MyoRing implantation in patients with keratoconus

Clinical relevance: This study was conducted to evaluate five-year outcomes of MyoRing implantation in patients with keratoconus. The results showed that MyoRing implantation is a minimally invasive procedure and is safe and effective for improving visual acuity and refraction in most patients with keratoconus.Background: The long-term effects of MyoRing implantation on corneal features were studied.Methods: A total of 48 keratoconic eyes of 43 consecutive patients who had undergone MyoRing implantation using the Pocket Maker microkeratome (Dioptex, gmbh, Linz, Austria) and who had completed five years of follow‑ups were included in this retrospective study. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction and keratometry (K) readings were measured and assessed pre-operation, and five years post-operatively. As well, post-operation satisfaction was assessed using a validated questionnaire.Results: Five years post-operatively, there was a significant improvement in UDVA, CDVA, K readings, spherical equivalent (SE), and manifest sphere and cylinder (p < 0.001). Mean UDVA was 1.20 logMAR before the surgery and 0.42 after the surgery (p < 0.001). Mean CDVA was 0.63 logMAR before the surgery and 0.20 logMAR after the surgery (p < 0.001). SE was improved from -6.53 dioptres (D) before the surgery to -2.23 D after the surgery (p < 0.001). Moreover, the results show that the mean K was reduced by 2.82 D after the surgery (p = 0.001). Overall, 81% of patients were moderately to highly satisfied five years after surgery.Conclusion: MyoRing implantation was found to be a minimally invasive procedure, and is safe and effective for improving visual acuity and refraction in most patients with keratoconus.

Intrastromal Corneal Ring Segments Implantation and Descemet Membrane Endothelial Keratoplasty for Coexisting Keratoconus and Fuchs Endothelial Dystrophy

PURPOSE

To report two cases of coexisting keratoconus and Fuchs endothelial dystrophy treated with intrastromal corneal ring segments (ICRS) implantation and Descemet membrane endothelial keratoplasty (DMEK).

METHODS

Two patients with coexisting keratoconus and Fuchs endothelial dystrophy underwent ICRS implantation and DMEK, in a two-stage procedure. Follow-up evaluation included Scheimpflug tomography and optical coherence tomography.

RESULTS

In both cases, ICRS implantation improved corneal topography and DMEK restored normal corneal thickness. Corrected distance visual acuity improved from 20/100 to 20/30 and from 20/60 to 20/25. Urrets-Zavalía syndrome was diagnosed in one case and addressed with colored contact lens fitting.

CONCLUSIONS

Low vision resulting from coexisting keratoconus and Fuchs endothelial dystrophy might be addressed more selectively with posterior lamellar keratoplasty and ICRS implantation. Urrets-Zavalía syndrome must be considered a possible complication after DMEK, especially in patients with keratoconus. [J Refract Surg. 2020;36(10):703-706.].

Allogenic corneal tissue transplantation in substitution for extruded intracorneal rings: A case series

We describe a case series of four eyes of four keratoconus patients with extruded intracorneal ring segments (ICRS) in whom donor corneal tissue was used to substitute for the extruded ICRS in an attempt to preserve its effect. In all patients, the extruded intracorneal ring was removed through the exposed area. Donor corneal tissue (tailored to the size and shape of the ICRS) was inserted into the empty ICRS tunnel and fixed in place using 10-0 nylon sutures. At three months follow-up, all patients had a healed graft and displayed a stable Kmax, best corrected visual acuity (BCVA) and corneal topography comparable to the preoperative values. Replacing extruded intracorneal rings with donor tissue grafts in keratoconus patients appears to be a promising technique in preserving the effect of the corneal ring and possibly in treating primary keratoconus with donor tissue segments. Refinement of the technique, longer follow-up, and a larger study population is warranted.

Late extrusion of intrastromal corneal ring segments: A report of two cases

Purpose

To report two cases of patients with late extrusion following uneventful implantation of intrastromal corneal ring segments (ICRS) for myopia.

Observations

Two patients with previously implanted ICRS for low myopia presented with spontaneous onset of extrusion of their ICRS, one at 7 years post-operatively and the other at 17 and 20 years. Both cases underwent explantation and maintained excellent best-corrected visual acuity. These cases represent the longest reported intervals between implantation of the ICRS and subsequent extrusion.

Conclusions and importance

Late extrusion can occur many years following implantation of ICRS, even in eyes without pre-existing thinning or ectasia. The technique for explantation described herein can result in favorable clinical outcomes in such cases. These cases demonstrate the importance of long-term follow up of eyes that have undergone ICRS implantation.

Safety and Efficacy of Sequential Intracorneal Ring Segment Implantation and Cross-linking in Pediatric Keratoconus

PURPOSE

To evaluate the safety and visual outcome of intracorneal ring segment (ICRS) implantation followed by cross-linking in pediatric keratoconus patients.

DESIGN

Retrospective interventional case series.

METHODS

This retrospective study included pediatric patients (aged ≤14 years) with keratoconus and poor corrected distance visual acuity (CDVA) that underwent ICRS implantation and cross-linking (CXL). ICRS were inserted under topical anesthesia after creating a corneal tunnel with a femtosecond laser. Cross-linking was performed 1 month subsequently. Records were reviewed and data collected preoperatively and at 6 months, 1 year, 2 years, and 4 years postoperatively.

RESULTS

Twelve patients (17 eyes; 10 male, 2 female) aged 9-14 years (mean age 12.3 years) received ICRS implantation followed by CXL. Follow-up times ranged from 6 months to 4 years after surgery. At the 6-month follow-up all eyes were evaluated; at the 1-year, 2-year, and 4-year follow-up 11, 10, and 7 eyes were evaluated, respectively. At the 6-month follow-up, mean CDVA in comparison to preoperative levels improved significantly (P = .001) from 0.30 ± 0.19 logMAR to 0.12 ± 0.1 logMAR; mean uncorrected distance visual acuity (UDVA) also improved significantly from 0.90 ± 0.50 logMAR to 0.43 ± 0.31 logMAR. A significant decrease in both keratometry readings and spherical equivalent (from -4.0 to -1.56 diopters) was also noted after ICRS insertion. At the 1-year, 2-year, and 4-year follow-up refractive values remained relatively stable in comparison to the 6-month follow-up, except for a minor but significant improvement in cylinder and, at 4 years, in UDVA. All patients tolerated the surgery well and no intraoperative or postoperative complications were reported, except for 1 ring segment that had to be removed after 2 years owing to vascularization and corneal thinning.

CONCLUSION

ICRS implantation is a safe and effective procedure for visual rehabilitation in children with keratoconus and poor CDVA.

Intrastromal Corneal Ring Segments in Children with Keratoconus

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.

Clinical, Refractive and Histological Reversibility of Corneal Additive Surgery in Deep Stroma in an Animal Model

PURPOSE

The aim was to evaluate the reversibility of the clinical and histological changes induced in the corneas of an animal model after removing an intracorneal ring segment (ICRS).

METHODS

Surgery for this study was performed in 38 eyes of an experimental animal model (Gallus domesticus) for ICRS surgery (Ferrara technique). The animals without complications were randomized to two groups; in all of them, 1 segment was implanted in each eye and later removed at different times (1 and 3 months after implantation). In each group, after explantation, corneas were processed at different times for histological analysis with hematoxylin and eosin (H&E) stain and electronic microscopy. The refractive state of the eyes was also measured.

RESULTS

In corneas without complications (88.23%), explantation was performed correctly. During the first few days, around the area where the ICRS was implanted we observed deposits of cells and a moderate degree of corneal opacity (haze). These signs decreased progressively without disappearing completely. Histologically, at 7 days, we observed hyperplasia and abnormal arrangement of collagen fibers. Later, these findings also decreased in both groups, albeit at a faster rate in group 1. Minimal changes were observed in electron microscopy up to the end of the study in both groups. Preoperative refractive state was achieved at 1 month after explantation in both groups.

CONCLUSIONS

ICRS can safely be explanted from the cornea. Refractive reversibility was achieved at 1 month after explantation. However, the clinical and histological findings after ICRS explantation depend on the time from implantation to explantation.

Reshaping procedures for the surgical management of corneal ectasia

Corneal ectasia is a progressive, degenerative, and noninflammatory thinning disorder of the cornea. Recently developed corneal reshaping techniques have expanded the treatment armamentarium available to the corneal specialist by offering effective nontransplant options. This review summarizes the current evidence base for corneal collagen crosslinking, topography-guided photorefractive keratectomy, and intrastromal corneal ring segment implantation for the treatment of corneal ectasia by analyzing the data published between the years 2000 and 2014.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Intrastromal Corneal Ring Segment Explantation in Patients With Keratoconus: Causes, Technique, and Outcomes

PURPOSE

To assess the causes for intrastromal corneal ring segment (Intacs; Addition Technology Inc., Lombard, IL) explantation in patients with keratoconus, and technique for explantation, long-term outcomes, and secondary procedures to correct visual acuity.

METHODS

Ten eyes of 8 patients with a history of Intacs explantation between 2004 and 2012 were included in a retrospective study performed at the Bascom Palmer Eye Institute, Miami, Florida. Causes of Intacs removal, surgical technique, preoperative and postoperative corneal examination, and uncorrected and corrected distance visual acuity were documented. Additionally, corneal topography (Tomey, Nagoya, Japan) parameters such as average keratometry and corneal cylinder were assessed.

RESULTS

Although the segments were well positioned, the most common cause of Intacs removal was worsening visual acuity (80%). There was no statistically significant difference between pre-Intacs placement, post-Intacs placement, and post-Intacs removal in uncorrected and corrected distance visual acuity, average keratometry, or corneal cylinder, except between 1-year post-Intacs placement corrected distance visual acuity (0.57 logMAR [20/75 Snellen]) and 1-month post-Intacs removal corrected distance visual acuity (0.25 logMAR [20/36 Snellen], P =.03). Four patients underwent penetrating keratoplasty after Intacs removal with good visual outcomes.

CONCLUSION

This study demonstrates the visual and structural outcomes that returned to near baseline after Intacs explantation in keratoconic eyes.

Tissue reaction after intrastromal corneal ring implantation in an experimental animal model

PURPOSE

To evaluate corneal wound healing in the hen animal model after additive surgery with an intracorneal ring segment (ICRS).

METHODS

We implanted one ICRS in each eye of 76 hens. In control group 1 (n = 22 hens), the stromal channel was prepared but no ICRS was inserted. In control group 2 (n = 2 hens), no surgery was performed. Animals were randomly separated into groups and euthanized after clinical follow-up of 4 and 12 hours, 1, 2, 3, and 7 days, and 1, 2, 3, 4, and 6 months. Corneas were stained with hematoxylin-eosin. Apoptosis was measured by terminal uridine nick end-labeling assays. Cell proliferation and myofibroblast-like differentiation were assayed by BrdU and α-smooth muscle actin immunofluorescence microscopy. Stromal matrix changes were documented by electron microscopy.

RESULTS

Epithelial and stromal cell apoptosis around the ICRS-implanted and control group 1 eyes peaked at 12 hours, but continued for 72 hours. In ICRS-implanted eyes, epithelial and stromal proliferation was present at 12 and 24 hours, respectively, and peaked at 7 days and 72 hours, respectively. Some proliferation in the ICRS-implanted group continued through the 6-month follow-up, and myofibroblast-like cells differentiated one to three months after ICRS implantation. The segments rotated within the stroma as the limbal inferior angle approached the epithelium.

CONCLUSIONS

Wound healing after ICRS implantation in hen corneas was similar to that of other corneal surgical wounds in stages. However, there were some specific features related to the small size of the epithelial wound and the device permanently implanted inside the cornea.

Intracorneal Ring Segment Reimplantation in Keratectasia

PURPOSE

The objective of this study was to evaluate the safety and potential for visual improvement of replacing INTACS with Kerarings in patients with keratectasia.

DESIGN

Retrospective case series.

METHODS

A review of patients undergoing intracorneal segment exchange was conducted. Ten eyes of 9 patients that underwent INTACS explantation and Keraring re-implantation were included. Visual acuity, manifest refraction, keratometry, and corneal asphericity readings were collected. Data were analyzed preoperatively, immediately before Keraring insertion, and at 3, 6, and 12 months after Keraring implantation.

RESULTS

The mean age of subjects was 44.5 ± 11.23 years. The mean time to exchange was 13.9 ± 9.8 months. The initial indications for surgery were post- Laser-Assisted in Situ Keratomileusis ectasia (n = 6) and keratoconus (n = 4). The removal and re-implantation procedure were successfully completed in all eyes without significant complications. No statistical difference was observed with respect to keratometry readings, manifest sphere, and manifest cylinder during follow-up. There was a significant improvement in mean decimal corrected distance visual acuity at 3, 6, and 12 months after Keraring insertion (P>0.05). The Q values were -0.37 ± 0.94 after INTACS implantation and -0.18 ± 0.62, 0.06 ± 0.31, and 0.00 ± 0.38 at 3, 6, and 12 months after insertion of Kerarings.

CONCLUSIONS

Replacement of INTACS with Kerarings appears to be a safe procedure and may lead to an increase in corrected distance visual acuity in some eyes. This may be related to the change in corneal asphericity as experienced by our cohort.

Long-term follow-up of intrastromal corneal ring segments in keratoconus

PURPOSE

To report the long-term follow-up of Ferrara intrastromal corneal ring segment (ICRS) implantation for the management of keratoconus.

SETTING

Private clinic, Belo Horizonte, Brazil.

METHODS

This study comprised patients with keratoconus who completed at least 5 years of follow-up. One or 2 ICRS were inserted in the cornea, embracing the keratoconus area. Statistical analysis included preoperative and postoperative uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and keratometry (K) values.

RESULTS

Thirty-five eyes of 28 patients were evaluated. The mean UDVA improved from 0.15 preoperatively to 0.31 postoperatively and the mean CDVA, from 0.41 to 0.62, respectively; the increases were statistically significant (P = .003 and P = .002, respectively). Corneal topography showed corneal flattening in all eyes. The mean minimum K value decreased from 48.99 D preoperatively to 44.45 D postoperatively and the mean maximum K value, from 54.07 D to 48.09 D, respectively; the decreases were statistically significant (both P = .000).

CONCLUSIONS

Five years after ICRS implantation, the UDVA and CDVA were improved in eyes with keratoconus. There was significant postoperative corneal flattening that remained stable over the follow-up period.

Clinical and research applications of anterior segment optical coherence tomography - a review

Optical coherence tomography (OCT) is being employed more and more often to image pathologies and surgical anatomy within the anterior segment, specifically in anterior chamber biometry, corneal pachymetric mapping, angle evaluation and high-resolution cross-sectional imaging. The cross-sectional imaging capability of OCT is similar to ultrasound, but its higher resolution allows OCT to measure and visualize very fine anatomic structures. No contact is required. In this review, we describe the utility and limitations of anterior segment OCT.

Outcomes of radiofrequency in advanced keratoconus

PURPOSE

To evaluate the use of radiofrequency energy to correct advanced keratoconus.

SETTING

Universidade Federal de Minas Gerais, Belo Horizonte, and Universidade de Ciências da Saúde de Alagoas, Maceió, Brazil.

METHODS

In this prospective comparative study, radiofrequency was applied to 25 eyes of 21 consecutive patients. One group comprised patients with a K-reading between 54.0 diopters (D) and 58.0 D; 8 thermal spots were placed at the 4.0 mm optical zone. The other group comprised patients with a K-reading greater than 58.0 D; 16 spots were applied at the 4.0 mm and 5.0 mm optical zones. The minimum follow-up was 18 months in all patients. Differences between preoperative and postoperative uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), manifest refraction, and K-readings were clinically and statistically evaluated.

RESULTS

At end of the 18-month follow-up, the mean BSCVA in the 8-spot group improved from 20/100 (0.71+/-0.25 logMAR) preoperatively to 20/40 (0.32+/-0.11 logMAR) and in the 16-spot group, from 20/200 (1.03+/-0.30 logMAR) to 20/60 (0.62+/-0.22 logMAR). The mean manifest refractive spherical equivalent (MRSE) improved from -7.70 D+/-5.20 (SD) preoperatively to -6.82+/-4.41 D after 18 months in the 8-spot group and from -11.33+/-6.70 to -8.38+/-5.12 D, respectively, in the 16-spot group. The mean best contact lens-corrected visual acuity was 20/30 (0.18+/-0.24 logMAR) in the 8-spot group and 20/40 (0.31+/-0.19 logMAR) in the 16-spot group. A dense corneal scar was seen in 1 patient in the 16-spot group at the 6-month follow-up.

CONCLUSIONS

Radiofrequency appeared safe for the treatment of advanced keratoconus. Contact lens fitting was stable in all cases.

Optical coherence tomography to assess intrastromal corneal ring segment depth in keratoconic eyes

PURPOSE

To investigate intrastromal corneal ring segment depth with a high-speed corneal optical coherence tomography (OCT) system.

SETTING

Doheny Eye Institute, University of Southern California, Los Angeles, California, USA.

METHODS

A prospective observational case series comprised 4 eyes of 4 patients receiving Intacs intrastromal corneal ring segments (Addition Technology, Inc.) for keratoconus. Optical coherence tomography (OCT) was performed between 7 days and 43 days after implantation.

RESULTS

The slitlamp impression of intrastromal corneal ring segment implantation depth did not correlate well with OCT measurements (r(2) = 0.68). The fractional implantation depth was correlated with several surgical variables using a stepwise multivariate regression model, and 2 statistically significant correlations were found. The position of the distal portions of the ring segments was shallower than that of the portion closer to the insertion site (P = .003). Segments placed in the inferior cornea (P = .008) experienced more distal shallowing. Shallower depth was associated with greater fractional anterior stromal compression (P = .04).

CONCLUSIONS

Shallower placement of intrastromal corneal ring segments may result in more complications, such as epithelial-stromal breakdown and extrusion, because of the greater anterior stromal tensile strain. The distal and inferior portions of intrastromal corneal ring segments tended to be placed at a shallower depth. Optical coherence tomography provided precise measurement of ring segment depth and may help identify implants that pose a greater risk for depth-related complications.

Intrastromal Corneal Ring Implantation (360° Ring) for Myopia: A 5-Year Follow-up

PURPOSE

Stability of correction is a major factor for successful refractive surgery. Intrastromal corneal rings were placed for the correction of low to moderate myopia beginning 10 years ago. The purpose of this study was to evaluate findings in patients 5 years after ring placement and to compare these findings with 1-year results to assess the stability of effect.

METHODS

Seventy-two patients (113 eyes) with myopia (range, -0.75 to -4.50 diopters [D]) were treated with the placement of intrastromal corneal rings (360 degrees ), in a multicenter clinical trial between 1993 and 1994 under U.S. Food and Drug Administration phase II and phase III clinical trials. Six insert sizes were evaluated: 0.21, 0.25, 0.30, 0.35, 0.40, and 0.45 mm. The long-term results that were evaluated were uncorrected visual acuity, best spectacle-corrected visual acuity, cycloplegic refraction spherical equivalent at 5 years and proximity of this value to the target refraction determined preoperatively, induced manifest refraction cylinder, and slitlamp findings.

RESULTS

Data at the 5-year follow-up showed that uncorrected visual acuity was 20/40 or better in 83% of eyes and 20/20 or better in 64% of eyes, compared to 88% and 43%, respectively, at the first year of follow-up. Only 7% of eyes lost two or more lines of preoperative best spectacle-corrected visual acuity at 5 years, compared to 11% at the first year. No eyes at the 1- or 5-year follow-up had a best spectacle-corrected visual acuity worse than 20/40. Cycloplegic refraction spherical equivalent was within 1.00 D of target refraction in 68% of eyes at 5 years, compared to 71% at the 1-year follow-up. Induced manifest refraction cylinder greater than 1.00 D was reduced to 5% of eyes in the fifth year, compared to 12% of eyes at year 1.

CONCLUSIONS

Intrastromal corneal rings are a safe, effective, and stable method of correcting mild to moderate myopia, and most patients continue to be satisfied with the results after 5 years. There was no clinically significant change in refractive effect and the central corneas remained clear at the 5-year follow-up in all eyes studied. Further data are currently being collected for 10-year follow-up periods. It is hypothesized that the use of intrastromal corneal rings as a refractive option for mild to moderate myopia will be supported by these additional longitudinal data.

Contact Lens Fitting for Keratoconus After Intacs Placement

PURPOSE

To describe a patient with keratoconus who underwent Intacs surgery to one eye with an unsatisfactory result and refused to undergo an Intacs removal procedure.

METHODS

Case report.

RESULTS

The patient's eye was fitted with a soft contact lens for visual rehabilitation 5 months after Intacs placement.

CONCLUSIONS

Intacs, with the help of secondary refractive procedures or contact lenses, may still be considered as effective in postponing penetrating keratoplasty, even in patients with advanced keratoconus.

Modified Intracorneal Ring Segment Implantations (INTACS) for the Management of Moderate to Advanced Keratoconus

PURPOSE

To evaluate the safety and efficacy of modified intracorneal ring segment implantation (INTACS) in the management of moderate and advanced keratoconus (KCN).

METHODS

A modified procedure of intracorneal ring segment (INTACS) implantation was performed in eyes with moderate to advanced keratoconus that were intolerant to contact lens or spectacle correction. The main outcome measures were uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), refraction, and keratometry. The preoperative values were compared with the values 6 and 12 months postoperatively.

RESULTS

Implantation was performed on 20 eyes of 15 patients; 9 were female and 6 were male. The mean age was 30.2 years (SD +/- 5.44; range, 23-40). At the 6-month follow-up, UCVA improved from 20/154 (SD +/- 0.11) preoperatively to 20/28 (SD +/- 0.21) postoperatively (P < 0.05); BCSVA improved from 20/37 (SD +/- 0.21) preoperatively to 20/22 (SD +/- 0.13) postoperatively (P < 0.05). Spherical refractive error improved from -3.38 D (SD +/- 3.12) to -1.15 D (SD +/- 1.84); cylindrical refractive error improved from -3.75 (SD +/- 2.04) preoperatively to -1.21 (SD +/- 0.84) postoperatively (P < 0.05); average keratometry decreased from 49.50 D (SD +/- 1.64) preoperatively to 46.35 D (SD +/- 1.50) postoperatively. The changes remained stable to the 12-month follow-up. There was 1 case of anterior chamber perforation. There were 6 eyes that had ring exposure secondary to corneal thinning over the implants 3-6 months postoperatively, and a dense corneal infiltrate developed in 1 patient at 7 months postoperatively.

CONCLUSIONS

The procedure appears to be effective in improving UCVA and BSCVA of patients with clinical keratoconus. In our small study group, however, there were significant (6/20) postoperative problems with regards to thinning and ring exposure.

Comparison of Topographic Corneal Irregularity After LASIK and Intrastromal Corneal Ring Segments in the Same Patients

PURPOSE

To retrospectively compare the irregularity of the corneal surfaces of 14 patients after LASIK in 1 eye and placement of intrastromal corneal ring segments (ICRS) in the other eye.

METHODS

In a within-patient comparison, Orbscan corneal topography was used to retrospectively compare the corneal surface irregularity of LASIK-treated and ICRS-treated eyes at an outpatient tertiary-care ophthalmology clinic in Sao Paulo, Brazil. For the anterior corneal surface, irregularity measurements were compared for both the central and peripheral areas of the cornea. The differences between each group were analyzed for statistical significance.

RESULTS

The corneal surfaces of eyes treated with ICRS were found to be more irregular than the corneal surfaces of eyes treated with LASIK, the mean irregularity being 1.91 for LASIK-treated eyes and 3.12 for ICRS-treated eyes in the anterior corneal surface and 0.51 for LASIK-treated eyes and 0.87 for ICRS-treated eyes in the posterior corneal surface. A statistically significant difference was noted only in the posterior surfaces.

CONCLUSIONS

When measured with Orbscan topography, ICRS-treated eyes show more corneal surface irregularity than LASIK-treated eyes. The difference in outcome for the two types of treatment may be due to the mechanical effect of the ICRS on the shape of the cornea.

Are intracorneal rings still useful in refractive surgery?

PURPOSE OF REVIEW

This article reviews the latest data published and presented at international meetings about the use of intracorneal ring segments in corneal and refractive surgery.

RECENT FINDINGS

The long-term data on intracorneal ring segments in the correction of low to moderate myopia indicate that they seem clearly comparable with laser in-situ keratomileusis, the most common refractive procedure worldwide. There is increasing interest in the use of intracorneal ring segments for the treatment of some complications after laser in-situ keratomileusis and for the control of some degrees of primary corneal ectatic disorders such as keratoconus and pellucid marginal degeneration.

SUMMARY

Intracorneal ring segments are and will be useful in several corneal and refractive abnormalities. Concern still exists about their predictability and the long-term effects of their use in primary and secondary ectasia.

One or 2 Intacs segments for the correction of keratoconus

PURPOSE

To evaluate the effect of implanting 1 or 2 intracorneal rings (Intacs, KeraVision) as a device to correct, stabilize, and/or improve the best corrected visual acuity in patients with clear cornea keratoconus oriented by the preoperative corneal topography pattern.

SETTING

Vissum/Instituto Oftalmológico de Alicante, Miguel Hernandez University, Alicante, Spain.

METHODS

In this prospective comparative consecutive study, Intacs segments were implanted in 26 keratoconic eyes with clear central corneas of 19 consecutive patients (9 women and 10 men). Corneas were divided into 2 groups according to the topographic pattern of the cone. Group I included keratoconus not crossing the 180 degrees meridian and Group II included keratoconus crossing the 180 degrees meridian. The Intacs were horizontally placed through a lateral clear corneal incision. According to the corneal topography 1 segment was implanted 0.45 mm inferior in Group I, and 2 segments were implanted, 1 0.25 mm superior and the other 0.45 mm inferior, in Group II. All cases completed a minimum follow-up of 1 year. Differences between preoperative and postoperative uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, and keratometry were clinically and statistically evaluated.

RESULTS

Spherical equivalent error and refractive astigmatism were significantly reduced. The mean keratometric values were reduced following Intacs insertion in both groups. At the end of the first year of the postoperative follow-up, Group I (1 segment) had an improvement in mean UCVA to 20/50 (0.4 +/- 0.22 decimal value), which was statistically significant when compared to the preoperative UCVA of 20/100 (0.2 +/- 0.13 decimal value) (P=.011). Mean BSCVA was 20/32 (0.62 +/- 0.24 decimal value), which was also statistically significant when compared to the preoperative BSCVA, which was 20/50 (0.4 +/- 0.21 decimal value) (P=.002). In Group II (2 segments), UCVA after 1 year was 20/63 (0.34 +/- 0.17 decimal value), which was statistically significant when compared to the preoperative UCVA of 20/400 (0.06 +/- 0.02 decimal value) (P=.001). Mean BSCVA was 20/32 (0.62 +/- 0.27 decimal value), which was significantly better than the preoperative UCVA of 20/50 (0.38 +/- 0.22 decimal value) (P=.001). In 4 eyes, the inferior segment was removed because of partial extrusion during the postoperative follow-up.

CONCLUSIONS

Treatment of keratoconus with 1 or 2 Intacs segments oriented by the preoperative corneal topography used in this study proved to be effective in decreasing the corneal steepening and astigmatism and improving BSCVA. Further follow-up is needed to determine the final effect of Intacs on the progression of the corneal disease.

INTACS Before or After Laser in situ Keratomileusis: Correction of Thin Corneas With Moderately High Myopia

PURPOSE

Intrastromal corneal ring segments (INTACS Micro-Thin Prescription Inserts by Addition Technologies, Fremont, Calif) were inserted as a combined surgery with laser in situ keratomileusis (LASIK) in six eyes with thin corneas to correct moderately high myopia.

METHODS

INTACS were implanted before LASIK (INTACS-LASIK) in three eyes and after LASIK (LASIK-INTACS) in three eyes. Mean preoperative manifest spherical equivalent refraction was -7.88 diopters. Mean follow-up was 306 days.

RESULTS

No intraoperative complications occurred. The LASIK-INTACS eyes were slightly more overcorrected than the INTACS-LASIK eyes because of the enhanced performance of INTACS in the thinned corneal tissue. Induced astigmatism by INTACS per se was less in the LASIK-INTACS eyes than in the INTACS-LASIK eyes. At last examination, uncorrected visual acuity was better than 20/25 in all eyes. Best spectacle-corrected visual acuity was within 1 line of the preoperative value in all eyes.

CONCLUSION

Both methods resulted in significant improvement in visual acuity and refraction. Based on our limited experience, however, LASIK followed by INTACS is preferred for reasons of safety, convenience, and lower induced cylinder.

Correction of astigmatism with short arc-length intrastromal corneal ring segments: preliminary results

OBJECTIVE

To evaluate the refractive effect of 130 degrees short arc length intrastromal corneal ring segments (ICRS) designed to correct myopia concurrent with astigmatism.

DESIGN

Prospective, nonrandomized, comparative (self-controlled) trial.

PARTICIPANTS

Ten eyes of 6 patients from one surgical center with manifest refraction spherical equivalent between -1.00 and -6.00 diopters (D), manifest cylinder correction between 1.00 and 6.00 D, and best spectacle-corrected visual acuity of 20/20 or better.

INTERVENTION

The patients were assigned to receive 1 of 6 ICRS thicknesses, ranging from 0.25 to 0.50 mm by 0.05 mm increments, with an arc length of 130 degrees.

MAIN OUTCOME MEASURES

Vector analysis of astigmatic correction. Efficacy was assessed by uncorrected visual acuity and by deviation of postoperative spherical and cylindrical refractive error from predicted correction. Safety was assessed by maintenance or loss of preoperative best spectacle-corrected visual acuity. Measurements were made before surgery and after surgery at days 1 and 7 and months 1, 2, 3, and 6.

RESULTS

At 6 months, uncorrected visual acuity was 20/20 or better in 80% of eyes (8/10) and 20/40 or better in all eyes. Eight of 10 eyes (80%) were within +/-0.25 D of plano spherical equivalent manifest refraction. There was no loss of best spectacle-corrected visual acuity, and 6 of 10 eyes (60%) gained a line. Reduction of keratometric cylinder by ICRS thickness was statistically significant (P = 0.039).

CONCLUSIONS

Preliminary results of visual and refractive performance after correction of compound myopic astigmatism using short arc length ICRS are promising.

Late bacterial keratitis after implantation of intrastromal corneal ring segments

We report a case of bacterial keratitis that occurred after implantation of intrastromal corneal ring segments (Intacs). The patient presented with decreased vision, inflammation, and stromal infiltrates localized at the extremity of an Intacs channel 3 months after surgery. Culture were positive for Clostridium perfringens and Staphylococcus epidermidis. The infiltrates progressed despite treatment with topical fortified and systemic antibiotics. The Intacs were removed. The keratitis slowly resolved, and the patient recovered a best corrected visual acuity of 20/20.

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.

Intracorneal rings to correct corneal ectasia after laser in situ keratomileusis

PURPOSE

To evaluate the potential of using intrastromal corneal ring technology (Intacs, KeraVision) to correct posterior ectasia after laser in situ keratomileusis (LASIK) for myopia.

SETTING

Department of Cornea and Refractive Surgery, Instituto Oftalmológico de Alicante, and Miguel Hernández University School of Medicine, Alicante, Spain.

METHODS

In this prospective noncomparative intervention case series, Intacs segments were implanted in 3 eyes that developed posterior ectasia after myopic LASIK with clear central corneas. Posterior ectasia and corneal thickness were tested using the Orbscan II Slit Scanning Corneal Topography/Pachymetry System (Orbtek Inc.). Segment thickness varied based on corneal topography analysis and refraction. The mean follow-up was 8.3 months (range 7 to 11 months).

RESULTS

The cases showed marked improvement after Intacs segment implantation. Postoperatively, there was a reduction in the magnitude of the posterior and anterior corneal surface steepening or ectasia and an increase in the topographical regularity index. In addition, the significantly enlarged optical zones resulted in a favorable visual outcome. In 2 eyes, the uncorrected visual acuity (UCVA) was 20/40 postoperatively. In the third eye, there was a residual refractive error; the UCVA was 20/50 and the best spectacle-corrected visual acuity, 20/40.

CONCLUSIONS

Intacs intrastromal corneal rings used as a mechanical device may alter the biomechanical properties of the cornea for the correction of iatrogenic keratectasia and the associated residual myopia.

Reversibility and exchangeability of intrastromal corneal ring segments

PURPOSE

To evaluate the effect of removal and/or exchange of intrastromal corneal ring segments (ICRS, Intacs); specifically the risk factors, degree of reversibility, and visual outcomes.

SETTING

Gimbel Eye Centres, Calgary, Edmonton, and Vancouver, Canada.

METHODS

Prospective cohort data were collected on 71 eyes that had ICRS placement by 3 surgeons at the Gimbel Eye Centres between August 1998 and July 1999. Data included patient symptoms, best spectacle-corrected visual acuity, uncorrected visual acuity (UCVA), manifest refraction, reason for removal or replacement, keratometry, corneal topography, and complications.

RESULTS

Twenty-four eyes (33.8%) had exchange or removal procedures because of underresponse, 20 eyes; overresponse, 2 eyes; and induced astigmatism and shallow placement, 1 eye each. Secondary procedures were removal and replacement, removal with subsequent laser in situ keratomileusis, and segment repositioning. Two risk factors for secondary surgery were identified: high preoperative refractive astigmatism and postoperative spherical equivalent greater than +/-0.5 diopter (D). The 6 eyes that had ICRS removal stabilized to within +/-0.25 D of the original refractive error with no surgically induced astigmatism within 1 to 7 weeks (mean 4 weeks) and had a final UCVA of 20/20 or better. In the 15 eyes that had ICRS exchange procedures, the UCVA improved by at least 1 line and median UCVA improved from 20/40 to 20/20.

CONCLUSION

Preliminary data from this study indicate that removal of segments resulted in reversal of the refractive effect.

Management of Corneal Ectasia After Laser in situ Keratomileusis With INTACS

PURPOSE

To evaluate the safety and efficacy of intrastromal corneal ring segments (ICRS, INTACS, Keravision) for the correction of corneal ectasia after laser in situ keratomileusis (LASIK).

METHODS

In this prospective, noncomparative case series, INTACS were implanted in three eyes (two patients) that were ectatic after LASIK. Mean follow-up was 8.7 months (range, 8 to 10 mo).

RESULTS

No intraoperative complications occurred. After INTACS implantation, uncorrected visual acuity ranged from 20/20 to 20/25 at 6 months and remained stable until 9 months. Mean postoperative spherical equivalent refraction was 0.50 D at 1 month and no significant changes appeared up to 9 months after INTACS implantation. After INTACS implantation, no eye lost any lines of Snellen spectacle-corrected visual acuity and two eyes gained from one to two lines. There was an increase in topographical regularity in all three eyes.

CONCLUSION

Implantation of INTACS in eyes with corneal ectasia after LASIK resulted in good refractive outcome, absence of complications, and improvement in visual acuity.

Intrastromal corneal ring segments for low myopia: a report by the American Academy of Ophthalmology

OBJECTIVE

This document describes intrastromal corneal ring segments (Intacs) inserts technology and examines the evidence to answer the key question about whether the treatment is safe and effective in correcting low myopia.

METHODS

A literature search that was conducted in September 2000 retrieved 13 relevant citations, and the reference lists of these articles were consulted for additional citations. Panel members reviewed this information and articles were rated according to the strength of evidence.

RESULTS

Prospective multicenter phase II and III clinical trials (Level II evidence rating) of Intacs inserts for myopia of -1.00 to -3.00 diopters (D), with a maximum of +1.00 D of astigmatism, enrolled a total of 452 subjects, with a total of 454 surgical attempts. The results from phase II and phase III were pooled for much of the analysis. At 1 year, 97% of patients who completed follow-up had 20/40 or better uncorrected visual acuity (UCVA). Seventy-four percent of patients had 20/20 or better UCVA. Ninety-two percent of eyes were within +/-1 D of intended refractive correction, and 69% were within 0.5 D of intended refractive correction. At 3 months, 90% of patients had less than 1.0 D of change from the previous examination performed at 1 month. The ocular complication rate, which was defined as clinically significant events but not resulting in permanent sequelae, was 11% at 12 months. The adverse event rate was 1.1%, defined as a serious event if untreated. Nearly 9% of patients requested to have their inserts removed and a total of 3.8% of patients required a secondary surgical intervention.

CONCLUSIONS

To date, evidence suggests that low myopia (-1 to -3 D) in a well-defined group of patients who have a stable manifest refraction and less than +1.0 D of astigmatism can be treated with Intacs inserts with a reasonable assurance of safety and effectiveness. Additional clinical research is needed to determine the long-term effectiveness of treatment and the comparative safety, effectiveness, and costs with other treatment modalities, including laser-assisted in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

Long-term follow-up of Intacs from a single center

PURPOSE

To evaluate the long-term visual results in patients having Intacs placement for the correction of mild myopia.

SETTING

Department of Ophthalmology, Mount Sinai School of Medicine and the Mount Sinai Hospital of Mount Sinai NYU Health, New York, New York, USA.

METHODS

Patients with mild myopia (spherical equivalent between -0.75 and -4.50 diopters [D]) were enrolled to have Intacs placement between May 1995 and March 1999 under United States Food and Drug Administration Phase II and Phase III clinical trials for intrastromal corneal ring segments (ICRS). Six insert thicknesses were evaluated: 0.21, 0.25, 0.30, 0.35, 0.40, and 0.45 mm. The long-term results evaluated were uncorrected visual acuity (UCVA), maintenance of best spectacle-corrected visual acuity (BSCVA), predictability and stability of the refractive effect, induced manifest refraction cylinder, slitlamp findings, self-reported visual symptoms, and maintenance of mesopic contrast sensitivity.

RESULTS

One hundred fourteen eyes of 73 patients were enrolled; 113 eyes of 72 patients received Intacs. There were no serious intraoperative or postoperative complications. The mean follow-up was 17.5 months +/- 8.9 (SD). At the end of this period (number of eyes evaluated = 100), the UCVA was 20/40 or better in 95 eyes (95.0%), 20/20 or better in 72 (72%), and 20/16 or better in 41 (41%). None of the 113 eyes lost 10 or more letters or 2 or more lines of preoperative BSCVA. The mean change in the cycloplegic refraction spherical equivalent for the 6 insert thicknesses was as follows: -0.75 +/- 0.00 D for 0.21 mm; -1.17 +/- 0.42 D for 0.25 mm; -2.00 +/- 0.54 D for 0.30 mm; -2.59 +/- 0.53 D for 0.35 mm; -3.09 +/- 0.54 D for 0.40 mm; and -3.82+/-0.80 D for 0.45 mm. The refractive correction was within +/-1.0 D of the predicted outcome in 103 eyes (92.0%) and within +/-0.5 D in 72 eyes (63.7%). Intacs were removed from 6 eyes (5.3%). All 4 eyes for which data were available 3 months after removal returned to within +/-0.5 D of their preoperative manifest refraction spherical equivalent. Intacs were exchanged because of undercorrection in 2 eyes (1.8%). These eyes gained 3 and 5 lines of UCVA 12 months and 18 months, respectively, after the exchange procedure. Overall, 85.7% (36/42) of the patients were satisfied with the results of the Intacs procedure.

CONCLUSION

Intacs safely and effectively corrected mild myopia. Placement is a brief, easy outpatient procedure. The refractive effect was predictable and stable over long-term follow-up. Results from a limited number of removal and exchange procedures indicate that Intacs are removable and adjustable.