Intrastromal Corneal Ring Segment Implantation Research Articles

Corneal densitometry changes in keratoconus patients after intrastromal corneal ring segments implantation

Background Keratoconus (KC) is an ectatic corneal disorder characterized by progressive corneal thinning with myopic astigmatism. Intrastromal corneal ring segments (ICRS) have been broadly selected as a surgical intervention for KC correction to delay the need of keratoplasty. The purpose of this study was to evaluate the corneal densitometry changes in the various annuluses and depths in KC corneas after intrastromal corneal ring segment (ICRS) implantation and to correlate those changes with the other optical and refractive outcomes. Methodology This was a prospective interventional study included 56 eyes of 40 patients with KC who underwent femtosecond laser-assisted Keraring ICRS implantation. The uncorrected and best-corrected visual acuities (UCVA and BCVA), refraction, keratometry, Q-value, thinnest corneal location thickness (TCLT), and corneal densitometry in all the annular zones were assessed preoperatively and 90 days after surgery. Results Following the ICRS implantation after 3 months, when compared to preoperatively, the UCVA, BCVA, improved significantly from 0.21±0.12 and 0.44±0.15 to 0.27±0.12 and 0.58±0.15 (P<0.001) and spherical equivalent (SE) decreased significantly, from −5.28±1.65 D to −4.05±1.24 D (P<0.001) whereas the K1, K2, Km, Kmax, reduced significantly from 47.67±4.10 D, 51.39±4.74 D, 49.44±4.28 D, and 57.78±7.35 D, to 44.28±2.86 D, 46.84±3.42 D, 45.45±2.98 D, and 53.89±5.49 D (P<0.001) respectively. Corneal astigmatism, and Q-value were markedly improved from 3.73±2.17 D and −0.99±0.5 to 2.55±2.08 and −0.28±0.5 (P<0.001) .As regard corneal densitometry there was a significant elevation in the mean density of 2–6 mm annulus for the anterior and posterior layers (P=0.001), of 2–6 mm and 6–10 mm annuluses and total diameter for the central layer (P<0.001, P=0.047, and P<0.001, respectively), and of 2–6 mm annulus and total diameter for the total corneal thickness (P<0.001 and P=0.014, respectively). In contrast, a significant decline in the densitometry readings was observed in the 10–12 annulus for the central, posterior, and total corneal layers (P=0.003, P<0.001, and P=0.008, respectively). The percentage changes in the corneal densitometry readings did not significantly correlate with the percentage changes in the UCVA, BCVA, SE, CA and Q value. The percentage changes in the central and total 2–6 mm annuluses densities correlated negatively with the percentage changes in the K1 (r=−0.30, P=0.025 and r=−0.29, P=0.029, respectively), K2 (r=−0.33, P=0.013 and r=−0.31, P=0.021, respectively), and Km (r=−0.34, P=0.010 and r=−0.33, P=0.014, respectively). Conclusions The ICRS implantation results in significant changes in corneal densitometry specifically in the central corneal layer and in the 2–6 mm annulus, with an inverse correlation with keratometric values of the front corneal surface. Besides, ICRS leads to substantial improvements of refractive status, visual acuity and corneal keratometry and asphericity.

Outcomes of 320-degree intrastromal corneal ring segment implantation for advanced keratoconus.

The purpose of this study is to investigate visual and tomographic outcomes and complications of long-arc length intrastromal corneal ring segment (ICRS) implantation for the treatment of advanced keratoconus. This retrospective study enrolled 10 eyes of 9 subjects. All patients received 320-degree ICRS (320-ICRS) implantation with femtosecond laser-assisted technique based on their advanced grading with preoperative high keratometry (K) value, asphericity (Q), and astigmatism. Medical records and corneal tomography changes of consecutive patients were reviewed at baseline, 1, and 3 months after treatment. There are 6 female and 3 male patients with a mean age of 29.6 ± 7.8 years in this study. Mean K (Km) reduced from 59.01 ± 5.81 D preoperatively to 50.7 ± 5.3 and 50.2 ± 3.66 postoperatively (after 1 month and 3 months respectively, P < 0.001). The changes in mean K, K1, K2, and maximum K (Kmax) reading were all statistically significant (all P < 0.001). Mean uncorrected distance visual acuity (UCVA) improved from 20/400 to 20/200. Mean best-corrected distance visual acuity (BCVA) improved from 20/100 to 20/60. Both UCVA and BCVA showed a trend of improvement at postoperative month 3, though insignificant in BCVA (P = 0.114). Mean Q improved from -1.59 ± 0.62 preoperatively to -0.48 ± 1.08 and -0.11 ± 1.04 postoperatively (after 1 month and 3 months respectively, P = 0.016, 0.002). No intraoperative or postoperative complications were observed. The present results suggest that implanting a 320-ICRS is a safe and effective procedure for treating patients with advanced keratoconus. Preoperative corneal measurements and the selection of types and thickness of ICRS are important to prevent unpredictable results.

Clinical outcome of intrastromal corneal ring segment implantation with two different nomograms in keratoconus patients

Aim The aim of this study was to assess the clinical effects of Keraring implantation in patients with keratoconus (KC) using a newly created nomogram (NN) based on cone location and Q value compared with the manufacturer’s standard nomogram (SN). Patients and methods This is a prospective randomized controlled clinical trial that included 100 keratoconic eyes of 100 patients. The patients were randomly assigned into two groups: group NN and group SN. Group NN underwent Keraring implantation based on the newly developed nomogram, while group SN followed the manufacturer’s standard nomogram. The primary outcome measures included visual acuity, different refractive measurements, keratometry values, and Q values, while the secondary outcome measure was Belin ABCD KC grading. All outcome measures were evaluated at 12 months postoperatively. Results The mean age of group NN was 22.96±7.45 years and that of group SN was 24.12±7.00 years, with no statistically significant difference (P=0.46). At 3 months postoperatively, group NN demonstrated substantial improvements compared with group SN. Group NN exhibited a greater improvement in uncorrected distance visual acuity [mean difference (MD) in LogMAR visual acuity=−0.61 compared with −0.31 in group SN, P&lt;0.0001] and corrected distance visual acuity (MD: −0.34 LogMAR compared with −0.05 LogMAR in group SN, P&lt;0.0001). Significant reductions were noted in sphere (MD: 4.22 D in group NN compared with 2.33 D in group SN, P&lt;0.0001), refractive cylinder (MD: 2.87 D in group NN compared with 1.74 D in group SN, P=0.003), and spherical equivalent (MD: 5.56 D in group NN compared with 3.12 D in group SN, P&lt;0.0001). Keratometric values and Belin ABCD grading system (particularly A and D categories) also showed more pronounced improvements in group NN than in group SN (P&lt;0.0001). Conclusion The personalized approach of the new nomogram (NN) based on cone location and Q value resulted in superior visual, refractive, and corneal topographic outcomes compared with the standard nomogram (SN) during the implantation of Keraring in KC patients. The individualized nomogram allowed for more precise corneal reshaping and restoration of corneal asphericity.

Comparative analysis of clinical and functional parameters in patients with stable stage II-III keratoconus after implantation of corneal segments and fitting of scleral rigid contact lenses

This study compares the effect of implantation of intrastromal corneal ring segment (ICRS) and fitting of individual scleral rigid contact lenses (RCLs) on visual functions in patients with stage II-III KC after previously performed corneal collagen cross-linking. The Helmholtz National Medical Research Center of Eye Diseases examined and treated 34 patients (69 eyes) aged 18 to 33 years with stage II-III KC. The study included patients who had previously undergone standard corneal collagen cross-linking. Depending on the type of optical correction, the patients were divided into two groups: patients in group 1 underwent ICRS implantation using a femtosecond laser; patients in group 2 were fitted with individual scleral RCLs. Improvement in clinical and functional parameters was observed in both groups. A higher clinical and functional result was achieved in group 2. For patients with stable stage II-III KC, it is advisable to recommend fitting of individual scleral RCLs for visual rehabilitation.

Effect of intrastromal corneal ring segments on in vivo corneal biomechanics in keratoconus: 1-year results.

To evaluate the 1-year effects of the implantation of intrastromal corneal ring segments (ICRS) in keratoconus (KC) on the dynamic corneal response (DCR) parameters obtained with the Corvis. Fernández-Vega Ophthalmological Institute, Oviedo, Spain. Prospective, single-center, clinical study. Included were patients who underwent ICRS implantation for KC over a period of 1 year. On the day of the surgery and at least 6 months after ICRS implantation, the following measurements were made: corrected distance and uncorrected distance visual acuity, corneal tomography indices with the Pentacam, biomechanically corrected intraocular pressure and the Corvis DCRs (integrated inverse concave radius, deformation amplitude ratio, stiffness parameter at first applanation, stress-strain index [SSI] and the highest concavity radius). 30 eyes were included with a mean follow-up time of 15 months. Statistical analysis showed that ICRS implantation induced significant improvements in corneal biomechanics measurements between preoperative and long-term follow-up as demonstrated by a significant increase in SSI (P = .003). To confirm that this difference was actually induced due to a stiffening between early postoperative (previously published) and long-term an additional t-test was done between month 1 and late follow-up which confirmed a significant stiffening in the value of SSI (P = .01). Patients implanted with ICRS alone for KC showed a significantly stiffer response due to increased structural support compared with preoperative values and 1 month postoperative.

Intrastromal corneal ring segment implantation in pediatric patients with keratoconus: long-term follow-up

Purpose: To evaluate the long-term outcomes of Intrastromal Corneal Ring Segments (ICRS) implantation in pediatric patients with keratoconus. Methods: Retrospective analysis of eyes with ICRS implantation in pediatric age. Uncorrected (UCVA) and best-corrected (BCVA) visual acuity, maximum and minimum keratometry (Kmax and Kmin), and corneal thickness at the thinnest point (CTTP) were evaluated preoperatively, 6 to 12 months after surgery, 5 years after surgery, and at the last follow-up visit (&gt;10 years after surgery). Results: Fourteen eyes (10 patients) were included. In 5 eyes all ICRS were explanted and in 1 eye, one of the segments was explanted. UCVA (p=0.028) and BCVA (p=0.028) improved 6 to 12 months after surgery and remained stable afterwards (p&gt;0.999). There was a decrease in Kmax and Kmin 6 to 12 months after surgery (p&lt;0.001 and p=0.012, respectively), with subsequent stability at the 5-year follow-up (p=0.736 and p=0.056, respectively). Kmax remained stable at the last follow-up (p&gt;0.999) but there was an increase in Kmin (p=0.028). There were no changes in CTTP (p=0.097). Conclusion: ICRS implantation seems to be a minimally invasive, and reversible procedure that leads to improvement of BCVA and keratometry readings. Despite this, the need for explantation increased overtime.

Outcomes of two different treatment modalities in mild to moderate keratoconus

PurposeTo describe visual and refractive outcomes of intrastromal corneal ring segments (ICRS) and toric implantable collamer lenses (TICL) implantation in cases of mild and moderate keratoconus.MethodsA prospective descriptive interventional case series. 40 eyes were allocated into two groups. First group (20 eyes) was treated with corneal collagen crosslinking (CXL) 1 month after ICRS implantation and the second group was treated using TICL after 1 year of CXL.ResultsBoth groups showed statistically significant improvement in spherical equivalent, cylindrical refraction, uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) over the follow-up period.ConclusionBoth ICRS and TICL are effective in treatment of mid and moderate keratoconus with more predictable visual results with TICL.

Detecting True Change in Keratoconus after Intracorneal Ring Segment Implantation.

Confirming the progression of keratoconus is of paramount relevance to providing the appropriate treatment. Real change should be considered consistent over time. It must be greater than the variability of the measurement of the device used to monitor the cornea. The present study aimed to assess the intraobserver repeatability and intersession reproducibility of a Scheimpflug camera in measuring corneal parameters in virgin keratoconus and intrastromal corneal ring segments (ICRS) implantation eyes to discriminate real change from measurement noise. Sixty keratoconus and 30 ICRS eyes were included. Corneal parameters were determined in three consecutive measurements and were repeated 2 weeks later. The precision within the same session for all parameters was better in the keratoconic eyes, with mean repeatability limits 33% narrower (range 13% to 55%) compared with ICRS eyes. Mean reproducibility limits were 16% narrower (range +48% to -45%) compared with ICRS eyes. The cutoff values to consider a real corneal shape change were lower for virgin keratoconic than for ICRS, except for the thinnest corneal thickness and Stage C (ABCD system), which were the opposite. Corneal tomography measurements in ICRS eyes showed worse accuracy than in virgin keratoconus, which should be taken into account by practitioners in patients' follow up.

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

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

Long-Term Follow-Up of a 150° Arc-Length Intrastromal Corneal Ring Segment Implantation in Post-LASIK Ectasia

Purpose To evaluate the outcomes of implanting a 150° arc-length intrastromal corneal ring segment (ICRS) using a femtosecond laser in patients with post-LASIK ectasia throughout a 5-year follow-up period. Methods This study enrolled 45 eyes of 45 patients diagnosed with post-LASIK ectasia who underwent a 150° arc-length Ferrara-type ICRS implantation. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities, residual refractive errors, and root mean square (RMS) for coma-like aberration were evaluated preoperatively and at 6-, 12-, 36, and 60 months postoperatively. Results Mean UDVA (logMAR) ameliorated from 0.53 ± 0.33 preoperatively to 0.26 ± 0.24 at 6 months postoperatively (p < 0.0001). Mean CDVA improved from 0.12 ± 0.13 to 0.04 ± 0.06 (p < 0.0001). Mean UDVA and CDVA remained stable throughout the 5-year follow-up (p > 0.1). No eyes lost lines of CDVA at any follow-up visit compared to preoperatively, and most eyes gained lines. The eyes with a refractive cylinder ≤ 2.00 D varied from 26.7% preoperatively to more than 75% at all postoperative follow-up visits. The maximum keratometry was significantly flattened (p < 0.0001), and the RMS for corneal coma-like aberration was halved (p < 0.0001). 93.3% of the eyes did not show signs of disease progression or regression of the visual or refractive outcomes at any follow-up visits. Conclusion These results suggest that implanting a single 150° arc-length Ferrara-type ICRS is a safe, effective and stable procedure for visual restoration in post-LASIK ectasia. In very few cases, visual and/or refractive instability was experienced throughout the follow-up.

Scheimpflug-Derived Corneal Lower and Higher Order Aberrations Post Intrastromal Corneal Ring Segments for Keratoconus.

Intrastromal corneal ring segments (ICRS) improve corneal topographic symmetry and reduce corneal aberrations through regularization of the corneal surface, thereby functioning as a viable surgical intervention for patients with keratoconus. This study aims to evaluate changes in lower- (LOAs) and higher-order aberrations (HOAs) amongst varying pupil sizes pre- and post- ICRS implantation in keratoconus patients. We specifically investigate the impact of pupil size on total corneal HOAs up to the 6th order. Twenty-one eyes that underwent ICRS implantation were included in this prospective interventional study. LOAs and HOAs measurements at the 6 mm, 4 mm, and 2 mm pupil diameters were collected preoperatively and at 6 months postoperatively using the Zernicke analysis function on a Scheimpflug device. ICRS implantation demonstrated a statistically significant effect in vertical coma with a -0.23 reduction (p = 0.015) for a 4 mm pupil size and a -1.384 reduction (p &lt; 0.001) for 6 mm, with no significant effect at 2 mm. Horizontal coma, astigmatism 0°, astigmatism 45°, trefoil 5th order 30°, and RMS HOA demonstrated significant reductions at 4 mm or 6 mm pupil sizes but not at 2 mm. Our analysis demonstrates a favorable effect of ICRS implantation on larger pupil sizes, suggesting the importance of pupil size as it correlates with HOAs reduction.

Intrastromal corneal ring segments implantation with the aid of a femtosecond laser in cases of mild to moderate keratoconus: A 3‐year study

AbstractPurpose: To evaluate the 3‐year results of femtosecond assisted intrastromal corneal ring segments (ICRS) implantation for the treatment of mild to moderate keratoconus.Methods: Prospective case series including 4 eyes of 4 consecutive patients with keratoconus.Each patient was implanted with ICRSs according to the preoperative topography and refraction. The segments were implanted in intracorneal pocket created with the FS200 femtosecond laser. Planning of the operation was done based on the nomograms provided by the manufacturer. Patients' follow‐up involved visual acuity measurement, refraction control, clinical examination, corneal topography (Pentacam and Orbscan) and anterior segment OCT. The operation was performed due to patients' unsatisfying spectacle corrected visual acuity and contact lens intolerance.Results: Preoperative average steep keratometry was reduced from 53,3D (range 50.7–55.7D) to 48.6D (range 46.9‐50D) 3 years postoperatively. Preoperative average topographic astigmatism was 5.35D (range 4.2–7.9D) while postoperative was 2.7D (range 0.7–4.3D). Refraction assessment showed reduction of the refractive astigmatism from 3.5D (range 2.0–5.0D) to 2,5D (range 0.5–3.75D) and improvement of spherical equivalent from −5.0D (range − 4.0 to −7.25D) preoperatively to −2.5D (range −1.25 to −3.25D) 3 years postoperatively. Average pre‐op spectacle corrected visual acuity was 4/10, when post‐op visual acuity assessment on Snellen scale showed average improvement by 2 lines (range from 0 to 5 lines).Conclusions: The femtosecond assisted ICRS implantation based on the results of our study, improved all patients' visual acuity, topographic and refractive parameters 3 years postoperatively.

Sequential intracorneal ring segment implantation followed by transepithelial phototherapeutic keratectomy and corneal cross-linking

To evaluate the safety and visual outcomes of intrastromal corneal ring segment (ICRS) implantation followed by transepithelial phototherapeutic keratectomy (te-PTK) and corneal cross-linking (CXL) in patients with mild keratoconus. Patients with mildkeratoconusand contact lens intolerance who underwent sequential ICRS implantation followed by phototherapeutic keratectomy and corneal CXL between April 2015 and July 2018 were retrospectively included in the study. Refractive and visual outcomes, satisfaction questionnaire and complications were recorded at the last follow-up (mean 9.5 months postoperatively). Twenty eyes of 17 patients were enrolled, including 5 women and 15 men. The mean time between the two procedures was 16 months. Based on values before the first procedure and 9.5 months after the second procedure, significant improvements were noted in uncorrected distance visual acuity (UDVA) (0.80±0.35 logMAR vs. 0.46±0.38 logMAR), corrected distance visual acuity (CDVA) (0.38±0.23 logMAR vs. 0.13±0.16 logMAR), maximal K (56.11±4 diopters [D] vs. 50.6±3.56 D), mean K (51.87±3.43 D vs. 48.45±2.91 D), cylinder (7.99±3.94 D vs. 4.23±3.49 D), and spherical equivalent (-3.84±3.36 D vs. -0.99±2.15 D) (P<0.01). Among the outcomes, we noted 5 (25%) superficial corneal scarring (haze); 75% of eyes gained>=1 logMAR line of CDVA. In all, 94.5% of patients reported that they were satisfied with their outcomes. Combining ICRS implantation followed by te-PTK and corneal CXL appears to be a safe and effective approach for improving visual outcomes and quality of life in keratoconus patients.

Intrastromal corneal ring segments followed by PRK for postkeratoplasty high astigmatism: prospective study.

To evaluate refractive and topographic results of the association of intrastromal corneal ring segments (ICRS) with photorefractive keratectomy (PRK) for the correction of high (>6.0 diopters [D]) postkeratoplasty astigmatism (PKA). University of São Paulo, São Paulo, Brazil. Prospective interventional study. Postpenetrating keratoplasty patients, intolerant to contact lens fitting, and with corneal astigmatism higher than 6.0 D were treated by the combination of ICRS and PRK from January 2017 to June 2019. First, patients underwent femtosecond laser-assisted ICRS implantation to reduce and regularize corneal astigmatism, and 3 months later, submitted to PRK for the residual astigmatism. Outcomes were obtained 12 months after PRK. The study comprised 30 eyes of 29 patients. Mean uncorrected distance visual acuity (logMAR) changed from 1.16 ± 0.37 in the preoperative to 0.69 ± 0.40 after ICRS ( P < .0001) and to 0.34 ± 0.29 12 months after PRK ( P < .0001). Mean spherical equivalent decreased from -5.19 ± 4.81 D in the preoperative to -3.38 ± 4.51 D after ICRS ( P < .0001) and to -2.30 ± 2.84 D after PRK ( P = .132). Mean topographic astigmatism decreased from 7.88 ± 2.13 D in the preoperative to 5.47 ± 2.29 D after ICRS ( P < .0001) and to 4.12 ± 2.93 D after PRK ( P = .003). Mean refractive astigmatism decreased from 7.10 ± 1.13 D in the preoperative to 4.61 ± 1.61 D after ICRS ( P < .0001) and to 2.58 ± 1.49 D after PRK ( P < .0001). After PRK, the mean correction index (CI) for corneal astigmatism was 0.77 ± 0.36. The ICRS/PRK combination resulted in a higher CI than ICRS only, both for corneal and refractive astigmatism. 2 eyes (8%) presented clinically significant opacification. Other complications were endothelial rejection (n = 1, 4%), infectious keratitis (n = 1, 4%), and ICRS extrusion after corneal melting (n = 1, 4%). The association of ICRS and PRK was effective for treating high PKA. This strategy improved visual acuity, spherical equivalent, topographic and refractive astigmatism and resulted in a high CI. Safety questions remain open and must be balanced against benefits.

Successful Management of Corneal Hydrops and Intrastromal Corneal Ring Segment (ICRS) Migration Following ICRS Implantation for Keratoconus

Patient: Male, 17-year-old Final Diagnosis: Acute corneal hydrops • intrastromal corneal ring segment migration Symptoms: Poor visual acuity • rigid contact lens intolerance Medication: — Clinical Procedure: Intrastromal corneal ring segment implantation • intrastromal corneal ring segment reimplantation Specialty: Ophthalmology Objective: Unusual or unexpected effect of treatment Background:Acute corneal hydrops refers to a rare complication of keratoconus and other ectatic disorders with potentially sight-threatening sequelae. Intrastromal corneal ring segment (ICRS) implantation is a surgical procedure performed as therapy for keratoconus when there is contact lens intolerance. ICRS migration along the tunnel made for its insertion is one of its most frequent complications. We believe this is the first published case of acute corneal hydrops and ICRS migration unfolding shortly after an uneventful ICRS implantation, and successfully managed with medical treatment and ICRS reimplantation, respectively.Case Report:A 17-year-old male, previously diagnosed with bilateral keratoconus 4 years earlier for which he underwent cross-linking surgery for both eyes 3 years prior, presented to our department for a first-time keratoconus assessment. His best-corrected visual acuity (BCVA) was 20/25 OD and 20/40 OS with rigid gas-permeable contact lenses. Due to contact lens intolerance in the OS and lack of custom-fit scleral lenses at the time, 2 ring segments (Ferrara, AJL Ophthalmic, Inc.) with an arc length of 160 degrees and 300 μm in size were implanted at a depth of 320 μm. Within 1 week, severe hydrops and ICRS migration emerged. Medical treatment provided resolution of hydrops and then ICRS reimplantation was performed without further complications, resulting in contact lens tolerance alongside a BCVA of 20/40 OS.Conclusions:Corneal hydrops is a challenging complication in ICRS implantation due to its infrequent occurrence and the severity of its potential sequelae. Prompt medical treatment and close follow-up are essential to obtain the best outcome in these instances.

Хирургический подход к лечению аметропии у пациентов с кератоконусом и катарактой

Purpose. To develop a two-stage surgical technique to the treatment of ametropia in patients with keratoconus and concomitant cataract. Material and methods. 33 patients (35 eyes) with stages II–III of non-progressive keratoconus and concomitant cataracts of various stages of maturity were operated on. The average age of the patients was 46.5±2.7 (41–63). The operations were performed according to our proposed two-stage method of treating ametropia in patients with KC and cataracts (Patent of the Russian Federation No. 2748634 of 28.05.2021). The first stage was the implantation of FE RRARA intrastromal corneal ring segments (ICRS) with thickness from 150 to 350 µm. To correct residual refractive error in 5–7 months after the 1st stage, patients underwent stage 2: cloudy lens was removed and replaced with toric posterior chamber intraocular lens (TIOL) – AcrySof IQ Toric (Alcon, USA), T-flex Toric RayOne (Rayner, UK). Results. After the first stage of the operation (ICRS implantation), the uncorrected visual acuity (NCVA) was 0.2±0.03, the best corrected visual acuity (BCVA) was 0.4±0.02. In 1 month after the 2nd stage (phacoemulsification + TIOL) NCVA was 0.64±0.11 and BCVA was 0.74±0.12. During the entire follow-up period after the surgery visual functions, refraction, and rotational stability of TIOL were stable. Conclusion. Conducting a two-stage surgical intervention in patients with keratoconus and cataracts allows to stop the progression of the disease and effectively correct the ametropia concomitant with keratoconus. Key words: keratoconus, cataract, intracorneal segments, ametropia, toric intraocular lenses

Astigmatic change as a predictor of intrastromal corneal ring segment late extrusion.

To evaluate changes in keratoconic corneas implanted with intrastromal corneal ring segments (ICRSs) that have been explanted because of late extrusion of the segment after >2 years. Vissum Miranza, Alicante, Spain; OftalmoSalud, Lima, Peru; Minya University Hospital, Egypt. Retrospective multicenter case series. 23 keratoconic corneas that were implanted for ≥2 years and explanted because of natural extrusion of the segment. Clinical measures of visual, refractive, topographic, pachymetric, and aberrometric data were analyzed. To perform exploratory factor analysis, the Kaiser-Meyer-Olkin (KMO) test was used to evaluate sampling adequacy. Factor analysis with VARIMAX rotation was used to determine the main factors of the inventory. The mean time interval was 5 years. Topographic findings were reversed nearly to the baseline level after segment explantation (Km: 48.97 ± 3.47 D pre implantation and 47.60 ± 3.67 D after explantation, P =.374). Significant worsened in refractive cylinder was found pre-ICRS extrusion (‒2.54 ± 3.40 D after implantation and ‒3.96 ± 1.72 before extrusion, P < .05). The main factor obtained in the preimplantation moment included keratoconus grade, keratometric readings, and visual acuities. After ICRS implantation, the most strength components were the refractive cylinder, corrected distance visual acuity, and uncorrected distance visual acuity. Corneal aberrations were the main factors in the pre-explantation analysis. ICRSs were safely extracted, with a reversal of the corneal topographic data to the preoperative level. A significant astigmatic change was shown in patients implanted with ICRSs before late extrusion of the segment, suggesting the role of this parameter as a prognostic factor of extrusion.

Evaluation of the effectiveness of combined staged surgical treatment in patients with keratoconus.

This study performs comparative assessment of the results of different types of two-stage surgical treatment in patients with keratoconus, including combination of corneal collagen cross-linking with intrastromal corneal ring segments followed by topography-guided photorefractive keratectomy. Prospective review of 101 patients (101 eyes) with keratoconus was performed. Patients underwent corneal collagen cross-linking (32 patients), intrastromal corneal ring segments (48 patients), and a combination of these two procedures (21 patients). Transepithelial topography-guided photorefractive keratectomy was performed as the second stage of treatment in all patients with obtained stable refractive results at 8 months after first stage. Main outcome measures were visual acuity (uncorrected distance and corrected distance) and corneal topographic indices. Comparison of the studied parameters after first stage surgical treatment between non-combined CXL and combined groups demonstrated a statistically significant difference for uncorrected distance visual acuity, corrected distance visual acuity, and cylindrical refraction values (p<0.05). We observed significant improvement of visual acuity and key corneal topographic indices after topography-guided photorefractive keratectomy in all study groups (p<0.05). In 50 (49.5%) patients customized excimer laser ablation gave the possibility of full spherical and cylindrical corrections. Ten eyes (10%) had delayed epithelial healing, no corneal stromal opacities developed. This study shows that combined two-stage surgical treatment of keratoconus, consisting of intrastromal corneal ring segment implantation with corneal collagen cross-linking followed by topography-guided photorefractive keratectomy, is clinically more effective to prevent keratectasia progression and increase visual acuity than the use of non-combined two-stage techniques.

Two-stage treatment of ametropia in patients with keratoconus and cataracts

Keratoconus (KC) is a progressive degenerative corneal disease, leads to the aberration of biomechanical and optical properties and thinning of the cornea, causes astigmatism and decreases visual acuity.Materials and methods. 33 patients (35 eyes) with stages II–III of non-progressive keratoconus and concomitant cataracts of various stages of maturity were operated on. The average age of the patients was 46.5 ± 2.7 (41–63) years old. The operations were performed according to our proposed two-stage method of treating ametropia in patients with KC and cataracts (Patent of the Russian Federation No. 2748634 of 28.05.2021). The first stage was the implantation of FERRARA intrastromal corneal ring segments (ICRS) with thickness from 150 to 350 μm. To correct residual refractive error in 5–7 months after stage 1, patients underwent stage 2: cloudy lens was removed and replaced with toric posterior chamber intraocular lens (TIOL) – AcrySof IQ Toric (Alcon, USA), T-fl ex Toric RayOne (Rayner, UK).Results and discussion. After stage 1 of the operation (ICRS implantation), the uncorrected visual acuity (NCVA) was 0.2 ± 0.03, the best corrected visual acuity (BCVA) was 0.4 ± 0.02. In 1 month after stage 2 (phacoemulsifi cation + TIOL) NCVA was 0.64 ± 0.11 and BCVA was 0.74 ± 0.12. During the entire follow-up period after the surgery visual functions, refraction, and rotational stability of TIOL were stable.Conclusions. Conducting a two-stage surgical intervention in patients with keratoconus and cataracts allows to stop the progression of the disease and effectively correct the ametropia concomitant with keratoconus.

Comparison between different tonometers following intrastromal corneal ring segments implantation.

To compare different intraocular pressure (IOP) readings in corneas with intrastromal corneal ring segments (ICRS) taken by three different tonometers; Goldmann applanation tonometry (GAT), air puff tonometer, and ocular response analyzer (ORA) corneal-compensated IOP (ORA-IOPcc) and determine the relation of these measurements to different corneal parameters taken by Pentacam. An observational cross-sectional analytic study included patients who underwent ICRS keraring implantation at 3 months. In each eye, the two rings were placed using the femtosecond laser assisted technique 5.5 or 6 mm from the center. IOP was measured using three different tonometers; GAT, air puff tonometer, and ocular response analyzer (ORA) corneal-compensated IOP (ORA-IOPcc). Fifty eyes of 30 patients (20 males and 10 females) aged 27.56 ± 6.38 years were included. IOP measurements by GAT, air puff tonometer, and ORA-IOPcc were 13.28 ± 2.13 mmHg, 10.47 ± 2.55 mmHg, and 13.19 ± 2.78 mmHg, respectively. Comparisons between air puff and each of GAT and ORA-IOPcc were statistically highly significant (p-value <0.001). IOP measurements taken by air puff tonometer were significantly lower than those taken by GAT and ORA-IOPcc. These differences were not constant across the pressure range but increased as the pressure values determined using GAT and ORA increased. ORA-IOPcc and GAT showed similar readings. No correlation was found between any of the IOP readings taken by the three tonometers and the central corneal thickness.