Comparison of the MyoRing implantation depth by mechanical dissection using PocketMaker microkeratome versus Melles hook via AS-OCT.

BACKGROUND: This paper seeks to evaluate the depth and outcomes of MyoRing implantation using two mechanical dissection procedures including: PocketMaker microkeratome in opposition to the Melles hook method. METHODS: This retrospective study was carried out on 39 eyes of 38 keratoconus patients (28 male and 10 female) with the mean age of [Formula: see text] years and had undergone MyoRing implantation by the two mentioned methods. The MyoRing was inserted into the corneal pocket which was made manually in 18 eyes (Melles hook group) or with PocketMaker microkeratome in 21 eyes (PocketMaker group). The mean follow up time was [Formula: see text] months with pre-operative and post-operative ophthalmic examination including uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), keratometry readings and central corneal thickness measurement. AS-OCT (Casia, SS-1000, Tomey, Nagoya, Japan) imaging was used to measure MyoRing insertion depth, exactly. RESULTS: Pre-operative and post-operative UCVA (LogMAR) mean change for the PocketMaker and Melles hook groups were recorded at 0.75 ± 0.32 and 0.78 ± 0.33, respectively. Similarly, BCVA (LogMAR) mean change were 0.27 ± 0.22 and 0.23 ± 0.22. Mean keratometry (Kmean) change were 6.06 ± 4.18 and 6.56 ± 3.55 respectively. UCVA change (P = 0.767), BCVA change (P = 0.77) and Kmean change (P = 0.693) showed that there was no statistically significant difference between both groups for any parameter. Depth measurements achieved from AS-OCT images showed that there was no statistically significant difference in pocket depth between two methods of MyoRing implantation (P = 0.413). CONCLUSIONS: The results of Myoring implantation outcomes using mechanical dissection via PocketMaker microkeratome as against Melles hook are comparable.

Intracorneal circular ring implant with femtosecond laser: Pocket versus tunnel.

PURPOSE: To evaluate and compare visual and refractive outcomes after implantation of the intracorneal continuous ring 360° arc (ICCR) versus the intracorneal ring segment 340° arc (ICRS) using femtosecond laser for central keratoconus. SETTING: Research Department, Oftalmosalud, Instituto de Ojos, Lima, Peru. METHODS: Randomized study that included 40 eyes of 32 patients diagnosed with central keratoconus between November 2014 and March 2015. Twenty eyes had an implantation of ICCR (MyoRing, Dioptex GmbH, Austria) through an intrastromal pocket and 20 eyes had an implantation of ICRS (Keraring, Mediphacos, Brazil) through an intrastromal tunnel. Both procedures were performed with a femtosecond laser (LDV Z6 model, Ziemer Ophthalmic Systems AG). Visual acuity (VA), refraction, and Scheimpflug imaging analysis were performed pre- and postoperatively at 1 month and 1 year. Comparisons of means were performed using the Student's t-test. RESULTS: At 1 year, uncorrected VA improved 0.77 LogMAR (p < 0.001) in the ICCR group and 0.79 LogMAR (p = 0.01) in the ICRS group; mean sphere improvement was 5.13 Diopters (D) in the ICCR group and 6.27 D in the ICRS group (p < 0.001 both); mean Steeper Keratometry improvement was 4.24 D in the ICCR group and 5.53 D in the ICRS group (p < 0.001 both). In the ICCR group, mean decrease in the pachymetry at the thinnest point of the cornea was 32.16 µm (p = 0.01), and in the ICRS group, mean increase was 4.2 µm at 1 year (p = 0.61). CONCLUSION: Intracorneal continuous ring 360° arc (ICCR) and intracorneal ring segment 340° (ICRS) are effective treatments for central keratoconus. No significant differences between rings were found on visual acuity, refraction, and keratometry improvement.

A novel Q-value-based nomogram for single intracorneal ring segment implantation versus standard manufacturer's nomogram combined with accelerated cross-linking for treatment of keratoconus: a randomized controlled trial.

PURPOSE: To compare the efficacy of implanting a single Keraring segment according to a novel Q-value-based nomogram (QN) to that of segment implantation according to the manufacturer's standard nomogram (SN), for keratoconus treatment. METHODS: This was a prospective, randomized controlled trial of 104 patients (104 eyes) with Amsler-Krumeich grade 1 or 2 keratoconus, and type 1 or 2 cone asymmetry determined according to manufacturer's classification. They were randomly distributed into two groups: group A patients (n = 52) underwent Keraring implantation according to the SN, and group B patients (n = 52) underwent implantation of a single (210° arc-length) Keraring segment according to the QN. Both treatments were combined with accelerated transepithelial cross-linking, and follow-up was 6 months. Main outcome measures were preoperative and postoperative visual acuity, subjective refraction and corneal topography. RESULTS: At postoperative month 6, group B exhibited statistically significantly higher values of mean uncorrected distance visual acuity (UDVA), sphere, K2, K-average, K-max and Q-anterior (p = 0.02, 0.01, 0.002, 0.001, 0.0001 and 0.03, respectively) compared to that of group A. However, group A exhibited better refractive cylindrical improvements (p = 0.04). In group A, we documented spontaneous extrusion of one Keraring segment. CONCLUSION: Single 210° arc-length segment implantation using our objective QN was more efficacious for keratoconus treatment than using the subjective SN. The nomograms were comparable when the Q-anterior value was >-1.00; however, the QN was superior to the SN when the Q-anterior value was ≤-1.00. The QN yielded greater postoperative UDVA and smoother corneal remodelling than did the SN for treatment of grade 1 and 2 keratoconic eyes.

Femtosecond-assisted intracorneal ring segment complications in keratoconus: from novelty to expertise.

OBJECTIVES: To document the difference between complication rate in the early curve of practicing intracorneal stromal rings and after gaining experience. PATIENTS AND METHODS: A retrospective study of 623 eyes of 417 patients with keratoconus who underwent Keraring implantation using femtosecond laser for channel creation. RESULTS: The main outcome measures were reported intraoperative and postoperative complications. The overall complication rate was 12.7% (79 eyes) over the 4 years with 34 eyes in the first year (5.5%) and six eyes in the fourth year (0.96%). Over the 4 years of our practice, intraoperative complications were 7.1% and postoperative complications were 5.6%. Yet, there was a significant difference in intraoperative complications between the first and the fourth year where it was 3.5% and 0.48%, respectively. This also applies to the postoperative complication rate, which decreased from 1.9% to 0.5% in the fourth year. CONCLUSION: Complications with femtosecond-assisted intracorneal stromal ring procedure can be reduced by experience, making this procedure a safe and effective means of treating keratoconus. Yet, there are some complications that cannot be avoided such as sterile keratitis.

The effect of soft contact lens thickness in visual function after intracorneal ring segments surgery.

OBJECTIVE: To study the influence of soft contact lens (SCL) central thickness and material in keratoconus on visual function after intracorneal ring segment (ICRS) surgery. METHODS: A pilot, experimental, prospective, cross-sectional and double-blind study was performed. Fourteen keratoconus patients with age range of 34.75±9.22years (7 males and 7 females) with ICRS implanted were involved in the study. Two different SCL materials [Hioxifilcon A (G-5X/p-GMA/HEMA) and Lucifilcon A (silicone-hydrogel)] with four different central thicknesses (0.1, 0.2, 0.3 and 0.4mm) were fitted in one eye per patient, selected randomly. High and low corrected distance visual acuity (CDVA) and contrast sensitivity (CS), corneal topography and corneal and total aberrometry were measured. RESULTS: Corneal spherical like, coma like and root mean square (RMS) decreased significantly for 0.3 and 0.4mm in both SCL materials (p<0.05). Total RMS decreased significantly for 0.4mm with both SCL materials (p<0.05). High and low CDVA improved for 0.4mm of thickness for both materials (p<0.05). Statistically increasing were found in all thicknesses studied for CS in both materials (p<0.05). CONCLUSION: A central thickness of the SCL equal or superior to 0.4mm seems to decrease the ocular high order aberration (HOA) and to improve the visual function in keratoconus patients implanted with ICRS. However, the modulus of rigidity of the SCL would not influence the HOA correction.

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.

The use of intracorneal ring segments in keratoconus.

Keratoconus is a corneal degeneration that usually appears during puberty and may seriously deteriorate the quality of life of the patients. This corneal disease is today the first indication of corneal transplantation in young patients. Until the last decade of the XX century, keratoplasty procedures were the only alternative to treat this pathological condition. In the beginning of the XXI century, intracorneal ring segments implantation was proposed as a therapeutic choice for treating keratoconus patients. Since then, several published articles have reported the benefits of this surgical procedure in treating this type of corneal ectatic disorder. The purpose of the present investigative work is to summarize the characteristic of the intracorneal ring segments and also to review the different features published in the literature in relation to this surgical technique for the treatment of keratoconus patients.

Feasibility of custom-made hydrogel contact lenses in keratoconus with previous implantation of intracorneal ring segments.

PURPOSE: To analyze the feasibility of a custom-made hydrogel silicone contact lens (CL) in keratoconus with intracorneal ring segments (ICRS) and to compare outcomes taking in consideration the geometry of the fitted lens-full periphery (FP) vs. sector management control (SMC). METHOD: A retrospective review of cases with previous KeraRings ICRS implantation and subsequently fitted with Kerasoft-IC CL was performed. The main outcome measurements were corrected spectacle distance visual acuity (CDVA), differences between flat and steep simulated keratometries (K-diff) and between steep and flat P values (CPV-diff), CL visual acuity (CLVA), wearing time (WT) and complications associated with wear. RESULTS: Thirty eyes of 22 patients and a follow-up time of 10.3±2.3 months were reviewed. Statistically significant improvement was observed between LogMAR CDVA and CLVA (0.25±0.19 vs. 0.04±0.05; P<0.0001). WT was 11.2h±1.2. Two eyes with mild corneal staining and another two with mild injection were noted. Twenty SMC designs were recorded and associated with lower levels of CDVA (0.36±0.22 vs. 0.18±0.10; P=0.006), CLVA (0.06±0.05 vs. 0.01±0.03; P=0.03), and larger amounts of CPV-diff (2.31±1.86 vs. 1.03±1.11; P=0.02) than those eyes fitted with FP designs. No statistical differences were found in the amount of K-diff and WT between both sub-groups. CONCLUSIONS: Fitting custom-made hydrogel silicone CL in keratoconus with ICRS is a feasible treatment with low rate of complications and adequate visual acuity and WT.

The effect of collagen cross-linking procedure on the material of intracorneal ring segments.

PURPOSE: To assess the potential impact of corneal crosslinking treatment (365 nm ultraviolet (UV)A irradiation with riboflavin) on the material properties of Intracorneal Rings Segments (ICRS). MATERIALS AND METHODS: Material properties were studied using FT-IR spectroscopy and UV-Vis spectroscopy. Rings were examined: (1) after installation of riboflavin solution, (2) after irradiation with UV-A light and (3) after instillation of riboflavin solution followed by instillation and coeval irradiation. The experiments followed the standard corneal cross-linking (CXL) protocol of corneal crosslinking treatment. RESULTS: After instillation of riboflavin solution, a permanent intense yellow staining of the samples was observed. UV-Vis spectroscopy confirmed that a certain amount of riboflavin solution was absorbed into the samples after CXL procedure. FT-IR spectroscopic analysis showed alterations in the spectra of ICRS mainly at the 2800-3200 cm(-1) spectral region [modification in band intensities of CH(2) (2925 cm(-1)) and CH(3) (2950 cm(-1))]. CONCLUSIONS: Our results suggest crosslinking reaction in ICRS material. This should be taken into consideration prior to any CXL treatment of post ICRS-implanted cornea.

A new approach based on Machine Learning for predicting corneal curvature (K1) and astigmatism in patients with keratoconus after intracorneal ring implantation.

Keratoconus (KC) is the most common type of corneal ectasia. A corneal transplantation was the treatment of choice until the last decade. However, intra-corneal ring implantation has become more and more common, and it is commonly used to treat KC thus avoiding a corneal transplantation. This work proposes a new approach based on Machine Learning to predict the vision gain of KC patients after ring implantation. That vision gain is assessed by means of the corneal curvature and the astigmatism. Different models were proposed; the best results were achieved by an artificial neural network based on the Multilayer Perceptron. The error provided by the best model was 0.97D of corneal curvature and 0.93D of astigmatism.