Intrastromal corneal ring segments to correct low myopia in eyes with irregular or abnormal topography including forme fruste keratoconus: 4-year follow-up

V4B implantable collamer lens versus Intacs corneal rings to manage anisometropic myopic amblyopia in children

OBJECTIVE

To compare the safety and efficacy of phakic intraocular lens (PIOL) versus intrastromal corneal ring segments (Intacs), for correcting high myopic anisometropia in amblyopic children.

DESIGN

Nonrandomized prospective multi-center study.

PARTICIPANTS

Thirty children, aged between 4 and 12 years, with unilateral high myopic anisometropic amblyopia were included in this study.

METHODS

Patients who were prospectively subdivided into group A, with mean preoperative manifest refraction spherical equivalent (MRSE) of -12.96 ± 4.17 D, underwent unilateral phakic posterior chamber intraocular lens implantation. Patients with mean preoperative MRSE of -8.60 ± 1.16 D in group B were treated by Intacs corneal rings. Pre- and postoperative visual acuity, ocular examination, stereoacuity, axial biometry measurements, cycloplegic refraction, and endothelial cell counts were performed in all patients.

RESULTS

Group A revealed prevention of amblyopia with improvement in spectacle-corrected distance visual acuity, where 4-6 lines were achieved in 77% of children, 2-3 lines in 4%, and just 0-1 lines restricted to 19% of children. Improvement in stereoacuity was noted in 93.33% of group A cases, whereas group B showed fewer cases of successfully improved vision, with 4-6 lines in 70% of children, 2-3 lines in 3%, and just 0-1 lines restricted to 27% of children. Improvement in stereoacuity was noted in 86.66% of cases. Two cases of cataract and 1 case of glaucoma with 1 case of uveitis were noted in the implantable contact lens (ICL) group.

CONCLUSIONS

Posterior chamber PIOLs or Intacs may provide a safe alternative in treating anisometropic myopic patients. Intacs implantation is safer with fewer complications than ICL. However, ICL implantation is advantageous over the corneal ring segment procedure owing to the wide range of errors to correct.

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.

Investigation of the efficiency of intrastromal ring segments with cross-linking using different sequence and timing for keratoconus

AIM

To evaluate and compare the efficacy and stability of intrastromal corneal ring segment (ICRs) implantation with cross-linking (CXL) using different sequence and timing.

METHODS

In this single retrospective study, 86 keratoconic eyes subjected the ICRs implantation. We analyzed only 41 eyes that had complete follow-ups. They were divided into three groups: ICRs implantation was applied only (group normal), ICRs first followed by CXL immediately (group CXL-S), CXL first followed by ICRs long after (group CXL-B). The visual acuity, refractive results, keratometry were compared preoperatively and 1y postoperatively. Their differences among the three groups were also analyzed.

RESULTS

Group normal comprised 25 eyes, group CXL-S 8 eyes, and group CXL-B 8 eyes. There were improvements in the mean uncorrected distance visual acuity (UDVA) and the mean corrected distance visual acuity (CDVA) compared preoperatively and 1y postoperatively {UDVA: 0.31 (P=0.030) logarithmic minimum angle of resolution [logMAR] group normal, 0.4 (P=0.020) group CXL-S, 0.45 (P=0.001) group CXL-B; CDVA: 0.21 logMAR (P=0.013) group normal, 0.30 (P=0.036) group CXL-S; 0.26 (P=0.000) group CXL-B}. The refractive and topographic outcomes also showed improvements. In terms of comparisons among the three groups, all the P values were above 0.05, showing no significant difference. But only group CXL-B had improvement in UDVA and CDVA for all the patients.

CONCLUSION

With safety and good visual outcomes, ICRs implantation is a viable alternative for keratoconus. No significant difference was found among these three groups.

Clinical outcomes after intrastromal corneal ring segments reoperation in keratoconus patients

AIM

To evaluate the clinical outcomes after Ferrara intrastromal corneal ring segments (ICRS) reoperation in patients with keratoconus.

METHODS

A total of 37 keratoconus eyes implanted with intrastromal corneal ring segments, which had an ICRS exchange, addition, reposition or removal were evaluated. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), keratometry (K), asphericity (Q) and pachymetry at the thinnest point (PTP) of the cornea were evaluated using a corneal tomography (Oculus Pentacam, USA).

RESULTS

The mean follow-up time after the reoperation was 30.5±9.7 months. The mean UCVA improved from 20/300 to 20/80 (P=0.005); the mean BCVA improved from 20/160 to 20/50 (P=0.0002), the mean keratometry reduced from 49.33±4.19D to 46.16±3.90D (P=0.0001), the mean pachymetry at the thinnest point increased from 450±42.9μm to 469±40.8μm (P=0.0001). The asphericity increased from -0.84±0.74 to -0.35±0.81 (P=0.15) and the spherical equivalent reduced from -4.64±4.87D to -3.04±3.45D (P=0.137). The changes in the asphericity and spherical equivalent were not statistically significant.

CONCLUSION

Ferrara ICRS implantation showed to be a reversible and readjustable surgical procedure for keratoconus treatment. Good outcomes can be obtained even after removal, addition, reposition or exchange of ICRS.

Keratoconus therapeutics advances

Keratoconus is a progressive, usually bilateral disease of the cornea that significantly diminishes visual acuity, secondary to a progressive corneal deformity which is characterized by corneal thinning, variable degrees of irregular astigmatism and specific abnormal topographic patterns. Normally it initiates during puberty and is progressive until the third or fourth decade of life, when normally the progression rate is diminished or waned. There are multiple scales to clinically classify keratoconus. One of the most commonly used is Amsler-Krumeich and recently with the development of morphometric and aberrometric techniques, additional scales have been created that allow keratoconus to be classified according to its severity. Despite certain etiology of keratoconus remains unknown, current treatment options are available in patients with ectatic corneas and they vary depending on the severity of the disease and they include spectacles, contact lenses, intrastromal rings, keratoplasty both penetrant or lamellar, cross-linking, refractive lens exchange with intraocular lens implant, phakic intraocular lenses and the combination of these alternatives. Some authors have been using excimer laser in patients with keratoconus but the safety of the procedure is controversial. Currently, the techniques for the management of keratoconus can be classified in 3 types: corneal strengthening techniques, optical optimization techniques and combined techniques.

Keratoconus in 18 pairs of twins

PURPOSE

To describe the concordance of keratoconus in 18 sets of twins.

METHODS

Thirteen monozygotic (MZ) and five dizygotic (DZ) pairs of twins were identified during an investigation of familial keratoconus. We used 16 forensic microsatellite markers to confirm the zygosity of same sex twins. Patients and available relatives were examined for signs of keratoconus using corneal topography. For each pair of twins, the severity of keratoconus in each eye was graded according to the steepest keratometry value and the average difference in score between the MZ and DZ twins compared.

RESULTS

All of the MZ twins and four of the five DZ twins were concordant for keratoconus but with differences in age of onset and severity of disease. The subjective age of onset of keratoconus tended to be earlier in the MZ twins (16.4 years, SD 4.66) than in the DZ twins (20.3 years, SD 7.55) (p=0.086). Additional relatives with keratoconus were identified in two (16%) of the families with MZ twins and in three (60%) of the families of DZ twins. The mean difference in severity scores was 1.4 (SD 1.73) for the MZ twins and 3.0 (SD 1.00) for the DZ twins (p=0.035).

CONCLUSION

This data provide evidence that the severity of keratoconus is more concordant in MZ than in DZ twins. The results support the currently accepted hypothesis of an important genetic contribution towards the pathogenesis of keratoconus, but suggest that there is also an environmental effect on the expression of disease.

Intrastromal corneal ring segment implantation for irregular astigmatism after laser in situ keratomileusis

We describe the case of a 56-year-old man with a previously decentered laser in situ keratomileusis ablation in his right eye that induced associated vision-threatening problems. After intrastromal corneal ring segment implantation, both topography and visual acuity significantly improved.

FINANCIAL DISCLOSURE

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

Collagen crosslinking and toric iris-claw phakic intraocular lens for myopic astigmatism in progressive mild to moderate keratoconus

PURPOSE

To report the long-term results of combined collagen crosslinking (CXL) and toric phakic intraocular lens (pIOL) implantation to correct myopic astigmatism in patients with progressive mild to moderate keratoconus.

SETTING

Instituto de Microcirugia Ocular, Barcelona, Spain.

DESIGN

Case series.

METHODS

From November 2006 to July 2009, CXL was performed in eyes with proven progressive keratoconus. Once refraction and topography stabilized, toric Artiflex/Artisan pIOL implantation was performed to correct residual myopic astigmatism. A complete ophthalmologic examination, including manifest refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, biomicroscopy, tonometry, fundoscopy, keratometry, corneal tomography, and central endothelial cell count (ECC), was performed before each procedure and postoperatively at 3 months and at yearly intervals up to 5 years. Main outcome measures were accuracy and stability of the spherical equivalent (SE) and cylinder, keratometry, UDVA (efficacy), CDVA (safety), central ECC, and complications.

RESULTS

The median follow-up in the 9 patients (17 eyes) was 36.9 months ± 15.0 (SD). The median interval between CXL and pIOL implantation was 3.9 ± 0.7 months. Fourteen eyes (82%) were within ± 0.50 diopter (D) of the attempted SE correction and 13 eyes (76%) were within ± 1.00 D of the attempted cylinder correction. The mean difference in simulated keratometry between preoperatively and the last follow-up was 0.17 ± 0.45 D (range -0.55 to 1.45 D). The postoperative UDVA was 20/40 or better in 16 eyes (94%). No eye lost lines of CDVA. No significant decrease in central ECC occurred (P>.05).

CONCLUSION

Combined CXL and toric iris-claw pIOL implantation effectively and safely corrected myopic astigmatism in progressive mild to moderate keratoconus.

FINANCIAL DISCLOSURE

Dr. Güell is a consultant to Ophtec. No other author has a financial or proprietary interest in any material or methods mentioned.

[Evaluation and quality assurance of refractive surgery procedures by the German Ophthalmological Society and the Professional Association of German Ophthalmologists. Status: May 2011]

The Commission of Refractive Surgery (KRC), which is a combined commission of the German Ophthalmological Society (DOG) and the Professional Association of German Ophthalmologists (BVA), has made an up-to-date evaluation of the operative techniques for correction of refraction errors. In the revised guidelines drawn up by the KRC for evaluation and safeguarding the quality of refractive surgical procedures the description, area of application, limitations, side-effects and complications of each procedure are given according to the published scientific literature. By this means a comprehensive explanation for and investigation of patients should be safeguarded, optimal treatment results achieved and complications avoided. In this article all relevant forms of refractive surgery (photorefractive keratectomy, LASEK, EPI-LASIK, LASIK, Femto-LASIK, RELEX, conductive keratoplasty, astigmatic keratotomy, limbal relaxing incisions, intracorneal ring segments, corneal cross-linking, phakic intraocular lenses, refractive lens exchange, corneal presbyopia implants, INTRACOR) are described in detail and quality guidelines are established. Refractive surgical care and additional medical services possibly arising prior to or following this treatment are not basically covered by the statutory health insurance (GKV).