[Surgical technique of keratoplasty with simultaneous implantation of a continuous ring or ring segment into the graft]. / Khirurgicheskaya tekhnika keratoplastiki s odnomomentnoi implantatsiei tsel'nogo ili razomknutogo kol'tsa v transplantat.

The article presents the surgical technique of penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) with femtosecond-laser assistance involving simultaneous implantation of an intracorneal continuous ring (ICCR) or an intracorneal ring segment (ICRS) into the graft. Surgical technique no. 1 - keratoplasty with simultaneous implantation of ICRS. Intrastromal circular tunnel is formed in the central zone of donor cornea using femtosecond laser. Then penetrating trepanation 8.1 mm in diameter is performed symmetrically to the formed tunnel. After preparing penetrating or lamellar recipient bed, suture fixation is placed in the corneal transplant, then the ICRS is implanted into the graft. Surgical technique no. 2 - keratoplasty with simultaneous implantation of ICCR. The donor cornea is dissected from periphery to center using femtosecond laser. Central zone remains untouched. A large diameter full-thickness trepanation is performed and the donor cornea is divided into the anterior and posterior layers. The ICCR is put on the donor cornea while holding the posterior layer with forceps. Penetrating or lamellar recipient bed is prepared, then the corneal graft is fixed with sutures. Transparent corneal graft acceptance does not guarantee high visual acuity due to post-keratoplasty astigmatism. Surgical correction of astigmatism is performed in the long term post-operatively and isn't effective enough. We proposed this new surgical technique of keratoplasty with simultaneous implantation of ICCR and ICRS into the graft as close as possible to the visual axis of the eye, which can help make the postoperative astigmatism minimal both immediately after surgery and in the long term. The study proposes a new approach to intraoperative prevention of post-keratoplasty astigmatism. The technique is simple, safe and effective. Analysis of long-term outcomes is required before recommending this method for widespread use in clinical practice.

Outcomes of two different treatment modalities in mild to moderate keratoconus.

PURPOSE: To 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. METHODS: A 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. RESULTS: Both 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. CONCLUSION: Both ICRS and TICL are effective in treatment of mid and moderate keratoconus with more predictable visual results with TICL.

Management of keratoconus: an updated review.

Keratoconus is the most common corneal ectatic disorder. It is characterized by progressive corneal thinning with resultant irregular astigmatism and myopia. Its prevalence has been estimated at 1:375 to 1:2,000 people globally, with a considerably higher rate in the younger populations. Over the past two decades, there was a paradigm shift in the management of keratoconus. The treatment has expanded significantly from conservative management (e.g., spectacles and contact lenses wear) and penetrating keratoplasty to many other therapeutic and refractive modalities, including corneal cross-linking (with various protocols/techniques), combined CXL-keratorefractive surgeries, intracorneal ring segments, anterior lamellar keratoplasty, and more recently, Bowman's layer transplantation, stromal keratophakia, and stromal regeneration. Several recent large genome-wide association studies (GWAS) have identified important genetic mutations relevant to keratoconus, facilitating the development of potential gene therapy targeting keratoconus and halting the disease progression. In addition, attempts have been made to leverage the power of artificial intelligence-assisted algorithms in enabling earlier detection and progression prediction in keratoconus. In this review, we provide a comprehensive overview of the current and emerging treatment of keratoconus and propose a treatment algorithm for systematically guiding the management of this common clinical entity.

Intracorneal ring segment implantation in advanced Keratoconus.

PURPOSE: To compare the clinical outcomes of intracorneal ring segment (ICRS) implantation in eyes with advanced vs. mild/moderate keratoconus (KCN). METHODS: A retrospective analysis of 141 eyes of 111 patients with KCN who underwent ICRS implantation. Preoperative maximum keratometry (Kmax) was <57 diopters (D) in 70 eyes and >57 D in 71 eyes. Postoperatively, corrected distance visual acuity (CDVA), Kmax, and intraoperative and postoperative complications were assessed at 1 day, 1 month, and 1 year. RESULTS: Corneas with a preoperative Kmax >57 D experienced greater reduction in axial curvature after ICRS implantation than corneas with a preoperative Kmax <57 D (7.0 D vs. 5.5 D, p=0.005) and gained more Snellen lines of CDVA (3 vs. 1, p<0.001) by 1 year postoperatively. The incidences of the most prevalent complications (explantation, extrusion, and infectious keratitis) did not differ significantly between the two groups (p=0.29, p=0.99, p=0.98). CONCLUSIONS: The visual and topographic effects of ICRS implantation are greater in eyes with more advanced KCN, with no increase in the incidence of the most common complications.

Allograft corneal ring segment for keratoconus management: Istanbul nomogram clinical results.

PURPOSE: To evaluate the clinical feasibility and visual outcomes of allograft corneal ring segment implantation for the treatment of keratoconus. METHODS: This case series, included forty-four eyes of 32 patients with a 6-month follow-up. All cases were treated according to the Istanbul nomogram. In the Istanbul Nomogram, corneal tunnels of 4 × 7.5 mm diameters are created at depth of 200 µm and implanted with sterile allograft corneal rings (KeraNaturalTM, Lions VisionGift, Portland, OR, USA) at the cone location. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent (SE) and keratometric values were compared preoperatively versus postoperatively. RESULTS: There was significant improvement in UDVA, CDVA, SE and topographic keratometric values. The mean preoperative CDVA (Snellen, decimal) increased from 0.29 ± 0.20, to 0.56 ± 0.26 (P < 0.001), at the last visit. There was no statistically significant difference between preoperative and postoperative thinnest pachymetry values (P = 0.509). No major complications or adverse event were observed during and after the operation. CONCLUSIONS: The results of this pilot study show that sterile allograft corneal ring segments may be safe, effective and enhance the visual performance of keratoconus patients. Larger clinical studies are needed to demonstrate the effectiveness and safety with long term follow-up.

Tear proteome profile in eyes with keratoconus after intracorneal ring segment implantation or corneal crosslinking.

Purpose: Keratoconus (KC) is a corneal ectasia characterized by structural changes, resulting in progressive thinning and biomechanical weakening that can lead to worsening visual acuity due to irregular astigmatism. Corneal collagen Crosslinking (CXL) and Intracorneal Ring Segment (ICRS) are widely used treatments in KC disease, but the alterations they cause in biomechanical mediators are still poorly understood. The aim of this study was to analyze the tear proteome profile before and after treatments to identify biomarkers altered by surgery. Materials and methods: An observational, prospective, case-control pilot study was conducted, analyzing tear samples from KC patients by nano-liquid chromatography-mass spectrometry (nLC-MS/MS). Data are available via ProteomeXchange with identifier PXD035655. Patients with KC who underwent ICRS surgery (n = 4), CXL (n = 4), and healthy subjects (Ctrl, n = 4) were included in this study. Clinical parameters were measured and tear samples were collected before and 18 months after surgery. Proteins with ≥2 expression change and p-value < 0.05 between groups and times were selected to study their role in post-operative corneal changes. Results: These analyses led to the identification of 447 tear proteins, some of which were dysregulated in KC patients. In comparisons between the two surgical groups and Ctrls, the biological processes that were altered in KC patients at baseline were those that were dysregulated as a consequence of the disease and not of the surgical intervention. Among the biological processes seen to be altered were: immune responses, cytoskeleton components, protein synthesis and metabolic reactions. When comparing the two treatment groups (ICRS and CXL), the process related to cytoskeleton components was the most altered, probably due to corneal thinning which was more pronounced in patients undergoing CXL. Conclusion: The changes observed in tears after 18 months post-operatively could be due to the treatments performed and the pathology. Among the deregulated proteins detected, A-kinase anchor protein 13 (AKAP-13) deserves special attention for its involvement in corneal thinning, and for its strong overexpression in the tears of patients with more active KC and faster disease progression. However, it should be kept in mind that this is a pilot study conducted in a small number of patients.

Combined corneal wavefront-guided transepithelial photorefractive keratectomy and accelerated corneal collagen cross-linking following intracorneal ring segment implantation in management of moderate keratoconus.

PURPOSE: Keratoconus (KC) leads to gradual progressive loss of vision in young and adult patients. For the purpose of visual rehabilitation and for hindering KC progression in patients, we designed this study. The main aim of this study is to help the KC patients to improve and stabilize their vision. METHODS: This prospective consecutive uncontrolled study includes 36 eyes of 36 patients with moderate degree of KC. All patients underwent combined wavefront-guided transepithelial photorefractive keratectomy (TPRK) and accelerated corneal collagen cross-linking (ACXL) after intracorneal ring segment (ICRS) implantation. Different measures will be evaluated at baseline, after ICRS implantation, and at one, 3, 6, and 12 months after combined (TPRK and ACXL). These measurements are uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), corneal indices based on Scheimpflug tomography, and higher-order aberrations (HOAs) based on (Sirius, Schwind) tomography. RESULTS: There were significant improvements in logMAR (UDVA and CDVA) and reduction in sphere, manifest cylinder, MRSE, maximal keratometry, and mean keratometry after ICRS implantation in the first stage. After TPRK and ACXL as the second stage, there were significant improvements in visual acuity of both logMAR UDVA and CDVA. Reduction in refractive outcomes, including MRSE, sphere, and manifest cylinder. All corneal indices including steep, flat, mean, and maximal keratometries had been decreased. Furthermore, there were significant improvements in the final root mean square, HOAs, and coma aberrations from baseline. CONCLUSION: In moderate KC, triple therapy of ICRS implantation followed by combined TPRK and ACXL appears to be a safe and effective approach. This approach provides an improvement in visual acuity, refraction, corneal indices, and HOAs. These improvements were maintained for 1 year postoperatively. It also halts KC progression.

Clinical, tomographic, and topometric outcomes of progressive thickness intracorneal ring segment implantations in duck-type keratoconus.

Purpose: To evaluate the visual, refractive, tomographic, and topometric outcomes of progressive thickness intracorneal ring segment (PT-ICRS) implantation in duck-type keratoconus. Methods: This retrospective study included eyes with oval (duck-type) keratoconus treated with PT-ICRS implantation. After the femtosecond laser tunnel creation, one PT-ICRS (Keraring AS 5 with 160° arc length) was implanted along the ectatic, inferior half of the cornea. Data of uncorrected and corrected distance visual acuity (UDVA and CDVA), refraction, asphericity (Q value), and keratometry (K) were compared pre- and postoperatively. Additionally, changes in the topometric indices of corneal irregularity were also evaluated after PT-ICRS implantation. Results: Thirty-one eyes of 30 patients were included in the study with a mean follow-up time of 9.06 months (ranging between 6 and 18 months). UDVA improved from 0.85 ± 0.36 to 0.27 ± 0.14 logMAR (P = 0.001), and CDVA improved from 0.37 ± 0.22 to 0.13 ± 0.11 logMAR (P = 0.001). The mean spherical error decreased from -3.66 ± 2.60 to -1.60 ± 1.42 D (P = 0.001), and the mean cylindrical error decreased from -4.91 ± 2.65 to - 1.41 ± 1.31 D (P = 0.001). All topographic parameters measured from the anterior cornea demonstrated statistically significant improvements after PT-ICRS implantation (P = 0.001). K mean, K maximum, corneal astigmatism, and Q value showed a significant decrease. Besides the index of height asymmetry, all topometric indices were significantly reduced after PT-ICRS implantation. There were no loss of lines and no complications. Conclusion: PT-ICRS implantation in duck-type keratoconus is an effective and safe treatment. This intervention improves the visual acuity, refractive error, topographical, and topometric parameters significantly by decreasing both eccentricity and steepness of the cone.

Evaluation of a new nomogram for Ferrara ring segment implantation in keratoconus.

AIM: To evaluate the short-term clinical outcomes of Ferrara rings in keratoconus using an optimized nomogram developed after several years of research and retrospective analysis of clinical data. METHODS: This prospective longitudinal non-comparative clinical trial evaluated 88 eyes of 88 patients (age 18-62y) with keratoconus diagnosis from two Spanish centers. Ferrara ring segment (AJL Ophthalmic) implantation was performed in all cases, using the mechanical procedure in 25 eyes (28.4%) and a femtosecond laser-assisted procedure in 63 eyes (71.6%). The ring segments implanted in each case were selected using a new optimized nomogram that considered variables such as anterior corneal asphericity and astigmatism or the discrepancy among astigmatism and coma orientations. Visual, refractive, corneal topographic, aberrometric, and pachymetric changes after surgery were evaluated during a 3-month follow-up. RESULTS: The implants induced a significant refractive change as well as an improvement in uncorrected (UDVA) and corrected distance visual acuity (CDVA; P<0.001). Postoperative CDVA of 0.10 logMAR or better was achieved in 28.4% and 46.5% of eyes, respectively. Two eyes (2.3%) lost two or more lines of CDVA whereas a total of 53.5% of eyes gained lines of CDVA. A significant central anterior and posterior corneal flattening was induced (P≤0.003), with a significant reduction of anterior (P<0.001) and posterior corneal astigmatisms (P=0.048), and a change in anterior asphericity (P<0.001). Total primary coma (6 mm pupil) change was also statistically significant (preoperative 3.66±3.04 µm vs postoperative 2.33±2.26 µm, P<0.001). No significant differences were found in the effect of ring segments between cases implanted using the mechanical and femtosecond techniques (P≥0.101). CONCLUSION: The implantation of Ferrara rings based on the nomogram evaluated is safe and effective for promoting a visual rehabilitation in keratoconus, with a relevant control of primary coma aberration.

Clinical outcomes after intracorneal ring segment implantation for keratoconus management in corneas with mild apical haze.

PURPOSE: The implantation of intracorneal ring segments represents an effective and safe therapeutic option for visual improvement in patients with keratoconus. The presence of corneal opacities is considered an exclusion criterion for this operation. METHODS: This is a retrospective cohort study of six eyes of six keratoconus patients at Queen Victoria Hospital, East Grinstead, UK, between January 2012 and December 2016. Femtosecond laser-assisted intracorneal ring segment implantation was performed in six eyes with apical corneal haze. Preoperative and postoperative visual acuity, keratometry readings, as well as corneal pachymetry were compared at 6-month follow-up. RESULTS: Uncorrected visual acuity (UCVA) [LogMAR] improved significantly from median 1.05 [95% confidence interval (CI): 0.83-0.13] preoperatively to 0.9 (95% CI: 0.63-1.00) at 6 months postoperatively (p = 0.03). Corrected visual acuity (CDVA) also improved significantly from median 0.75 (95% CI: 0.43-1.00) preoperatively to 0.4 (95% CI: 0.23-0.50) at 6 months postoperatively (p = 0.03). Keratometric readings, K-max (diopters) and K-mean (diopters), decreased significantly from 54.5 and 47.85 preoperatively to 53.45 and 46.42 postoperatively, respectively (p = 0.03). Corneal pachymetry showed no significant changes postoperatively. CONCLUSION: The results of this study show that the presence of apical haze should not exclude the implantation of intracorneal ring segments in patients with keratoconus.

[Intracorneal ring segments in keratoconus management]. / Les anneaux intra-cornéens dans la prise en charge du kératocône.

Intracorneal ring segments (ICRS), used in the management of keratoconus since the 2000s, have enjoyed significant technological development. Various types of ICRS exist, whose arc length, thickness, and diameter can be chosen according to the desired effect on the spherical equivalent, keratometry and asphericity. Individualized implantation strategies, based on each patient's topographic and tomographic pattern, are constantly evolving. The surgical procedure is standardized, and complications remain very rare. Combined procedures (corneal collagen cross-linking and refractive photokeratectomy±topo-guided, phakic and pseudophakic intraocular lenses) are increasingly used and require a good knowledge of the effect of ICRS alone on the keratoconic cornea. The objective of this review is to summarize clinical practices used in the visual rehabilitation of keratoconic patients using the ICRS+- combined procedures.

The number of intracorneal ring segments in asymmetric and central cones.

BACKGROUND: To compare the results of single versus double intracorneal ring segment (ICRS) (KeraRing) implantation in keratoconus with respect to different cone locations. METHODS: Twenty-two eyes of 18 patients with totally asymmetric cones (20-80% or 0-100% distribution along steep axis) were implanted with single ICRS (Group 1), 38 eyes of 32 patients with central or partially asymmetric cones (50-50% or 40-60% distribution along steep axis) were implanted with double ICRS (Group 2), at a depth of 80% of the site of implantation, in channels created with femtosecond laser device. All patients had uncorrected and corrected distance visual acuities (UDVA and CDVA, respectively) of ≤ 0.3 Snellen lines. RESULTS: In both groups, patients had median UDVA and CDVA gain of 3 Snellen lines (P > 0.05). Postoperative improvement in indices of vertical asymmetry and height decentration in Group 1; simulated keratometry, corneal astigmatism and anterior corneal asphericity values in Group 2 were greater (P < 0.05). A total of 10 eyes (45.5%) in Group 1 were recommended double ring implantation by the manufacturer's nomogram, but underwent single ICRS implantation and achieved visual, refractive, tomographic outcomes comparable to that in Group 2, although corneal cylindrical correction was less and final topographic astigmatism was greater. CONCLUSION: Double ICRS implantation seems to be superior in terms of keratometry, corneal astigmatism and anterior corneal asphericity improvement. Single ICRS implantation in totally asymmetric cones seems to provide satisfactory visual, refractive and tomographic results, similar to double ICRS implantation in central and partially asymmetric cones, by inducing central shift of the cone.

[Excimer laser in keratoconus management]. / Le laser excimer dans la prise en charge du kératocône.

Visual rehabilitation in keratoconus is a challenge, notably because of the significant irregular astigmatism and optical aberrations that it induces. Many surgical techniques have been developed in addition to, or in the case of failure of, spectacles and rigid gas permeable contact lenses: intracorneal ring segments, intraocular lenses, excimer laser and, as a last resort, keratoplasty. Excimer laser photoablates the cornea, allowing remodeling of its surface. There are various treatment modes (wavefront-optimized, wavefront-guided and topography-guided), allowing performance of a customized treatment if needed. Its use in keratoconus has been described since the 2000s, alone or in combination with other procedures. For example, the combination of photoablation and corneal cross linking, a technique that increases corneal rigidity and in so doing can slow or even stop the progression of keratoconus, proved its efficacy and safety in many studies, and various protocols have been described. A triple procedure, including intracorneal ring segments, excimer laser and cross linking, has also given some very promising results in progressive keratoconus, providing a significative improvement in visual acuity and topographic data. The combination of excimer laser and intraocular lenses remains a poorly explored lead that might provide some satisfactory results. The objective of this review is to summarize the recent data on excimer laser in keratoconus management.

Outcomes of sequential intracorneal ring segment and phakic intraocular lens insertion for visual rehabilitation in keratoconus.

PURPOSE: To report the visual and refractive outcomes of sequential intracorneal ring segment (ICRS) and toric phakic intraocular lens (IOL) insertion for visual rehabilitation in keratoconus. METHODS: A retrospective interventional cohort study was performed through the Corneoplastics unit and Eye Bank, Queen Victoria Hospital, East Grinstead, United Kingdom. RESULTS: 14 eyes of 12 patients had sequential ICRS and phakic IOL implantation for visual rehabilitation of keratoconus between June 2014 and February 2018. After at least 6 months follow-up, the number of eyes with an uncorrected distance visual acuity (UDVA) of 20/40 UDVA or better increased from zero (0%) to 10 (71%). 12 (85.7%) eyes achieved a post-operative UDVA equal to or better than the pre-operative corrected distance visual acuity (CDVA). The number percentage of eyes with a CDVA of 20/40 or better increased from 3 (31%) to 14 (100%). The mean final spherical equivalent improved from -4.07 to -0.17 (p ⩽ 0.001). The mean refractive astigmatism magnitude improved from 4.76D to 1.23D (p = 0.002). Seven (50%) eyes had 1.0D or less of refractive astigmatism post-operatively. CONCLUSION: In this cohort of eyes with keratoconus, sequential ICRS and phakic IOL implantation resulted in excellent visual and refractive outcomes after at least 6 months.

The Effect of Age on Corneal Topographic Indices, Keratometry and Visual Acuity After Combined Intrastromal Corneal Ring Segment (ICRS) Implantation and Corneal Crosslinking.

We aimed to assess age-related changes in corneal topographic indices, keratometry and visual acuity after sequential intracorneal ring segment implantation (ICRS) and crosslinking (CXL). This was a retrospective matched case-control series including 26 eyes of patients ≤18 years as cases and 26 eyes of adult patients as controls. All eyes received ICRS+CXL for progressive keratoconus. Eyes were matched regarding the keratoconus parameters and the treatment (type, number and thickness of ICRS). Data was analyzed for refractive and topographic values (uncorrected and corrected distance visual acuity (UDVA; CDVA) sphere; cylinder; spherical equivalent; maximum keratometry (Kmax); flat keratometry (Kflat); steep keratometry (Ksteep); all 7 pentacam topographic indices) preoperatively and one year postoperatively. Preoperatively, there was no significant difference for any refractive, clinical or topographic parameters between the groups except for index of vertical asymmetry. After one year, children had a significantly higher improvement in Ksteep (3.05D) than adults (2.10D; P=0.036) and a trend to significance for Kflat (2.7D compared to 1.78D, respectively; P=0.081). UDVA improved by 4.3 ETDRS lines in children compared to 3.3 ETDRS lines in adults and CDVA improved by 1.7 ETDRS lines in children compared to 1.2 ETDRS lines in adults, but with no statistical significance. The effects on keratometry indicated that corneal response after ICRS and CXL for keratoconus is more pronounced in young patients than adults. This assumption is also supported by functional improvement and by the fact that a few eyes (5) of some very young patients (<13years) showed highly remarkable improvements after surgery (higher than any adult eye).

Characterization of the effect of intracorneal ring segment in corneal ectasia after laser refractive surgery.

PURPOSE: To evaluate the visual, refractive, topographic, pachymetric, and biomechanical outcomes after intracorneal ring segment implantation in corneas with post-LASIK ectasia. METHODS: Retrospective longitudinal study enrolling 26 eyes of 22 patients with post-LASIK ectasia and undergoing intracorneal ring segment implantation (KeraRing®, Mediphacos) using a 60-kHz femtosecond laser (IntraLase®, IntraLase Corp.) for corneal tunnelization. Visual, refractive, anterior, and posterior corneal topographic (Pentacam HR, Oculus), pachymetric, and corneal biomechanical changes (Ocular response Analyzer, Reichert) were evaluated during a 12-month follow-up. Vector analysis of astigmatic changes was performed. RESULTS: A statistically significant reduction of sphere (p = 0.043) was observed at 1 month after surgery, with a significant improvement of uncorrected distance visual acuity associated (p = 0.019). Likewise, a significant reduction of anterior corneal power measurements (p ⩽ 0.014) and steepest posterior keratometric reading (p = 0.006) were observed at 1 month postoperatively, with no significant changes afterwards (p ⩾ 0.133). No significant changes were observed in manifest cylinder (p ⩾ 0.175), corrected distance visual acuity (p ⩾ 0.174), flattest posterior keratometric measurement (p ⩾ 0.282), volumetric measurements (p ⩾ 0.051), and corneal biomechanical parameters (p ⩾ 0.068). Vector analysis revealed an initial trend to overcorrection of astigmatism, with a trend to undercorrection at the end of follow-up and a significant variability in the outcome achieved in each patient. CONCLUSION: The implantation of KeraRing segments in post-LASIK corneal ectasia generates a significant modification of spherical refraction and a visual improvement due to a central corneal flattening generated. More refined nomograms of implantation in these cases should be developed to achieve a more predictable correction of astigmatism.

Effect of the variability in implantation depth of intracorneal ring segments using the femtosecond laser technology in corneal ectasia.

PURPOSE: To analyze the impact of the depth of implantation of intracorneal ring segments on morphological, biomechanical, and clinical outcomes in ectatic corneas. METHODS: This prospective longitudinal study enrolled 40 eyes of 29 patients (age 20-51 years) with corneal ectasia that underwent intracorneal ring segments implantation (KeraRing, Mediphacos). Changes in visual acuity, refraction, corneal tomography, and corneal biomechanics (Ocular Response Analyzer, Reichert) were evaluated during a 6 month follow-up. Likewise, changes in ring segment implantation depth measured by optical coherence tomography (Visante OCT, Carl Zeiss Meditec) were also evaluated. RESULTS: Mean relative depth of implantation was 71.6 ± 5.8%, 71.5 ± 6.5%, and 71.9 ± 6.3% at 1, 3, and 6 months after surgery, respectively (p = 0.827). The difference between the real relative depth of implantation and the theoretical attempted value of 70% was not statistically significant (p = 0.072). Differences in spherical equivalent during the follow-up changed significantly depending on the level of relative depth of implantation (p = 0.036), with an increase of 0.114 D per each 1% increase in relative depth of implantation. Likewise, a decrease of -0.194 D in the steepest keratometric reading was found per each decrease of 1% in relative depth of implantation (p = 0.026). Changes in corneal thickness (p = 0.092) and biomechanics (p = 0.080) were not related to relative depth of implantation. CONCLUSION: The effect on visual acuity and refraction of intracorneal ring segments when implanted in corneal ectasia is less clinically relevant when the implantation is done at a very deep plane. The variability of the depth of intracorneal ring segments implantation when using femtosecond laser technology is minimal and with no clinically significant effect on clinical outcomes.

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.

Unexpected visual improvement after aborted intracorneal ring segment implantation for keratoconus.

PURPOSE: To present a case of a complicated intracorneal ring segment (ICRS) implantation procedure in a patient with keratoconus, who experienced significant visual improvement, although the ICRS implantation had to be aborted. METHODS: A 25-year-old female patient with keratoconus underwent femtosecond laser-assisted ICRS implantation in her right eye (OD) for improving visual acuity. RESULTS: The procedure had to be aborted, because ICRS implantation was not possible. Anterior segment imaging 1 month after the procedure showed full-thickness corneal incision with corneal microperforation. However, patient's visual acuity improved significantly due to amelioration of the keratometric findings. Keratometric and visual improvement was preserved at 6 months postoperatively. CONCLUSION: Our case report shows that femtosecond laser-assisted full-thickness corneal incision on the astigmatic axis combined with the intracorneal tunnel creation resulted unexpectedly in keratometric and visual improvement in this keratoconus patient, even without the implantation of the ICRS.

Visual quality with corneo-scleral contact lenses after intracorneal ring segment (ICRS) implantation for keratoconus management.

PURPOSE: To evaluate the visual quality results when fitting a corneo-scleral contact lens (CScL) after intracorneal ring segment (ICRS) implantation for keratoconus management. METHODS: Twenty-seven eyes of 27 patients with keratoconus underwent ICRS implantation and had CScL fitted as their visual quality was unsatisfactory with their spectacles or contact lenses. Patients received a complete eye examination, refraction and visual acuity assessment, anterior eye biomicroscopy, ocular fundus examination, corneal topographic analysis, endothelial-cell count, and visual quality assessment using contrast sensitivity and aberrometry tests. A diagnostic trial set was used in the fitting process, and patients were assessed according to a standardised methodology, including subjective visual quality and comfort, and contact lens usage time. The follow-up period was one year. RESULTS: After fitting CScL, log-MAR visual acuity values improved significantly in relation to the best spectacle-corrected vision (0.22 ± 0.17 vs 0.00 ± 0.12; p < 0.001). Total high-order aberrations decreased 33% (2.62 ± 1.31 vs 1.75 ± 1.81 µm; p < 0.009) and the spatial frequencies of contrast sensitivity all improved (all p < 0.05). Furthermore, 70.37% of patients reported high ratings of subjective visual quality (favourable and very favourable) and prolonged usage times (11.78 ± 3.93 h). After wearing CScL for one year, no adverse ocular effects or clinically relevant changes in corneal parameters, visual quality, comfort ratings or usage time were found. CONCLUSION: This CScL appears to be an alternative reasonable option for keratoconic eyes with ICRS placement, providing an improvement in subjective visual quality.