Donut-shaped Corneal Allogeneic Intrastromal Segment as an Alternative to Deep Anterior Lamellar Keratoplasty in Advanced Keratoconus.

PURPOSE: The aim of this study was to describe a new technique of selective corneal stromal transplantation for keratoconus treatment, donut-shaped CAIRS (corneal allogeneic intrastromal ring segment). METHODS: A donut-shaped corneal graft is obtained using a double-bladed trephine. Descemet membrane, endothelium, and epithelium are all removed from the graft. Only stromal tissue is transplanted. A wide 360-degree intrastromal tunnel is created using the femtosecond laser, with a 30-degree angulation. The diameter is from 5.4 mm to 8 mm optical zone. After dehydration, the corneal graft is inserted into the tunnel. We report the clinical and tomographic outcomes after the procedure in 3 patients. RESULTS: The mean follow-up time after donut-shaped CAIRS was 6.01 ± 1.02 months. In case 1, best spectacle-corrected visual acuity improved from 20/150 to 20/40. In case 2, it improved from 20/400 to 20/40, and in case 3 from 20/200 to 20/40. The mean preoperative K was 57.3 ± 4.5 D and reduced to 44.2 ± 2.5 D after donut-shaped CAIRS. The mean spherical equivalent decreased from -9.8 ± 3.2 preoperatively to -3.2 ± 2.2 postoperatively. No intraoperative or postoperative complications were observed. Anterior segment OCT showed a mid-stroma implant, fusiform in shape, equidistant from the epithelium and endothelium. CONCLUSIONS: Donut-shaped CAIRS is a variation of the traditional CAIRS technique and showed to be an alternative option for keratoconus treatment, especially in moderate to advanced cases with a central clear cornea without scars. The technique is minimally invasive, and the visual axis remains untouched.

Results of intrastromal corneal ring implantation in advanced keratoconus With the aim of postpoing or avoiding corneal transplantation.

PURPOSE: To evaluate the safety and efficacy of the surgery of intracorneal ring segment implantation with 320° of arc (320-ICRS) in patients with advanced keratoconus stage IV and maximum keratometry (Kmax) above 60 D. METHODS: A prospective, interventional case series study evaluating 25 eyes of 19 patients with keratoconus stage IV and Kmax > 60D in which 320-ICRS were implanted using VisuMax® femtosecond. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), keratometric values (mean - mean-K, flat - K1, and steep - K2), maximum keratometry (Kmax), tomographic astigmatism, refractive astigmatism and asphericity (Q) were assessed preoperatively and at 3, 6 and 12 months after the procedure. RESULTS: The UDVA improved from 1.03 ± 0.28 LogMAR (20/200) to 0.54 ± 0.21 LogMAR (20/60), (p < 0.001), the CDVA (with glasses) improved from 0.63 ± 0.29 LogMAR (20/80) to 0.31 ± 0.16 LogMAR (20/40),(p = 0.004), K1 reduced from 54.41 ± 4.46 D to 49.36 ± 4.11 D (p < 0.001), K2 reduced from 61.15 ± 4.37 D to 53.715 ± 4.05 D, (p < 0.001), mean-K reduced from 57.55 ± 4,17 D to 51.44 ± 3,94 D (p < 0.001), Kmax reduced from 69.80 ± 8.20 D to 63.43 ± 6.31 D (p < 0.001) and asphericity (Q) changed from -1.57 ± 0.35 to -0.77 ± 0.56 (p < 0.001). A total of 89.9% patients reached BCVA wearing scleral contact lens  0.2 LogMAR(20/25). CONCLUSION: 320-ICRS to treat advanced keratoconus appears to be an efficacious and safe procedure, being a surgical alternative to delay or even prevent corneal transplantation.

Corneal densitometry in patients with keratoconus undergoing intrastromal Ferrara ring implantation.

OBJECTIVE: Evaluation of central corneal densitometry changes following Ferrara corneal ring segment implantation in patients with keratoconus, especially the correlation between corneal densitometry and keratometry. METHODS: Retrospective, non-comparative, interventional study based on the review of medical records of patients diagnosed with keratoconus who underwent Ferrara corneal ring segment implantation. Pre and post-operative corneal densitometry measurements obtained with Pentacam HR (Oculus, Wetzlar, Germany) were analyzed. The follow-up time was 3 months, and data comparison was made, using specific statistical analysis, with the data of 3 months postoperatively. RESULTS: The study sample consisted of 43 eyes of 36 patients. The mean corrected visual acuity improved from 0.82 LogMAR preoperatively (SD ± 0.33) to 0.19 LogMAR (SD ± 0.13) postoperatively. The mean spherical equivalent varied from -4.63 (SD ± 3.94) preoperatively to -2.16 (SD ± 2.63) postoperatively. Asphericity varied from -0.69 (SD ± 0.32) preoperatively to -0.27 (SD ± 0.31) postoperatively. The mean maximum K was 54.01D (SD ± 3.38) preoperatively and 51.50D (SD ± 2.90) postoperatively. The mean anterior densitometric value was 18.26 (SD ± 2.03) preoperatively and 17.66 (SD ± 1.84) postoperatively. CONCLUSION: Corneal densitometry is an interesting technology that should be studied in keratoconus patients. Our results suggest that the corneal densitometry in the cornea's anterior layer reduces after ICRS implantation and correlates with corneal keratometry. Further studies should be performed to increase the knowledge in this field.

Visual and Tomographic Outcomes of a 300° Arc-length ICRS Implantation in Moderate to Advanced Central Keratoconus.

PURPOSE: To assess the outcomes of implanting a new 300° arc-length intrastromal corneal ring segment (ICRS) in moderate to advanced central hyperprolate keratoconus. METHODS: Forty-two eyes with moderate to advanced central hyperprolate keratoconus were evaluated before and after implanting an inferior 300° ICRS (AJL Ophthalmic). The clinical measurements taken included manifest refraction, uncorrected (UDVA) and corrected (CDVA) distance visual acuity (logMAR scale), and corneal tomographic analysis (Sirius; Costruzioni Strumenti Oftalmici). Changes in the anterior and posterior corneal surfaces and the root mean square (RMS) for coma-like aberrations for a pupil size of 4.5 mm were evaluated. All examinations were performed before surgery and 6 months after surgery. RESULTS: The mean UDVA improved from 1.12 ± 0.48 logMAR preoperatively to 0.73 ± 0.37 logMAR postoperatively (P < .0001). The mean CDVA changed from 0.33 ± 0.20 to 0.20 ± 0.11 logMAR (P < .0001). Postoperatively, the CDVA improved by two or more lines in 45.2% of the eyes and increased by one line in 19.04%, and none of the patients lost lines of CDVA. All of the anterior and posterior corneal tomographic parameters analyzed were significantly improved after surgery, except posterior flat keratometry, which remained unchanged. In 80.95% of the eyes, the postoperative mean keratometry was 50.00 diopters or less. The 6-month RMS for coma-like aberrations also declined significantly from 1.57 ± 0.68 to 1.06 ± 0.42 µm after surgery (P < .0001). CONCLUSIONS: These results suggest that implanting a 300° arc-length ICRS is a safe and effective procedure for treating patients with moderate to advanced central hyperprolate keratoconus and clear cornea. [J Refract Surg. 2021;37(4):249-255.].

Evaluation of keratoconus progression and visual improvement after intrastromal corneal ring segments implantation: A retrospective study.

OBJECTIVE: To investigate the role of ICRS in halting keratoconus progression in a large sample of patients. METHODS: A retrospective, non-comparative, interventional study based on the review of medical records of patients diagnosed with keratoconus who underwent Ferrara corneal ring segment implantation. A retrospective chart analysis study of 123 operated eyes with follow-up ranging from 3 to 16 years (mean 5.3 ± 3.6 years) was performed. This study was carried out at Ocular Surgery Unit, São Paulo, Brazil. All topographic data were obtained from Pentacam (Oculus, Arlington, USA). The same surgeon performed all surgeries, and the Ferrara ICRS nomogram was used for ICRS selection in all cases. RESULTS: Corrected distance visual acuity, keratometry, and topographic astigmatism improved in most cases, with statistical significance. In 42 eyes (53.8%), there was an increase in K1 or K2, and in 36 (46.2%), there was a reduction or maintenance in K1. Considering a difference higher than 1 D, between 3-month post-surgery and final visit (group 3), 32 eyes (41%) showed an increase, and 46 eyes (59%) ended equal or below this value. CONCLUSION: The implantation of ICRS showed improvement in visual and keratometric indexes. The majority of patients did not increase more than one diopter in keratometric values after ICRS implantation. ICRS may be effective for slowing disease progression, especially in older patients.

Preliminary results of a new intrastromal corneal ring segment as a tissue saving procedure in photorefractive keratectomy to correct moderate to high myopia.

AIM: To evaluate the clinical results after implantation of a new intrastromal corneal ring segment (ICRS) associated with photorefractive keratectomy (PRK) to correct high myopia (HM) patients with thin corneas. METHODS: We evaluated 42 eyes of 23 HM patients that had ICRS implantation followed by PRK. The mean age of patients was 29.1±7.12y (range 18 to 40 years old). Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), keratometry, spherical equivalent, pachymetry, and aberrometry were compared using ANOVA with repeated measurements evaluated preoperatively and at last follow-up visit after the procedures. The refractive predictability and simulated/real corneal ablation were also assessed. RESULTS: The mean follow-up time after PRK was 6.8±1.6mo. The mean preoperative UCVA improved from 20/800 preoperative to 20/100 after ICRS and 20/35 after PRK. The mean preoperative BCVA was 20/25 (range from 20/30 to 20/20) and remained unchanged after ICRS implantation. Following the PRK the mean BCVA was 20/25 (range from 20/30 to 20/20). The mean spherical equivalent decreased from -7.25±1.12 (range -5.00 to -9.00) preoperatively to -3.32±1.0 (range -2.00 to -5.00) postoperatively (P<0.001) after ICRS implantation and decreased from -2.44±1.51 preoperatively to 0.32±0.45 (range -0.625 to 0.875) postoperatively (P<0.001) after PRK. The change in BCVA and topographic astigmatism was statistically significant (P<0.0001). CONCLUSION: ICRS in HM associated with PRK can be a tissue saving procedure and an alternative surgical option for correction of moderate to high myopia.

Intracorneal Ring Segments Implantation Outcomes Using Two Different Manufacturers' Nomograms for Keratoconus Surgery.

PURPOSE: To compare the outcomes of intracorneal ring segments (ICRS) implantation in keratoconic eyes with a similar tomographic pattern, using two different manufacturers' nomograms for surgical planning. METHODS: ICRS were implanted alternately in patients with the same tomographic pattern of keratoconus divided into two groups according to the surgical planning proposed by the ICRS manufacturers (Keraring, Mediphacos, Belo Horizonte, Brazil, and Ferrara Ring, AJL Ophthalmics, Vitoria, Spain). Visual, refractive, keratometric, corneal aberrometry, and optical quality changes were evaluated during a 6-month follow-up. Corneal and manifest refractive astigmatic changes were also analyzed using the double-angle polar plot and the Alpins vectorial method through the following components: target induced astigmatism, surgically induced astigmatism, difference vector, correction index, angle of error, index of success, flattening effect, and torque. RESULTS: After ICRS implantation, both groups showed significant improvement (P < .05) in visual and keratometric data. Corneal aberrometric changes and optical quality improvement were also statistically significant in both groups, except for trefoil (P > .05 in all intervals). The Alpins method analysis showed a better performance in the Keraring group, but with no statistically significant difference between groups (P > .05). Comparison between groups showed a statistically significant difference only in tomographic astigmatism in double-angle polar plot analysis (P = .03), with more significant improvement in the Keraring group. CONCLUSIONS: Both manufacturers' nomograms resulted in statistically significant improvement in most of the parameters analyzed, with greater correction of corneal tomographic astigmatism in the group operated on according to the spherical equivalent/tomographic astigmatism nomogram. [J Refract Surg. 2019;35(10):673-683.].

Computational Models for Optimization of the Intrastromal Corneal Ring Choice in Patients With Keratoconus Using Corneal Tomography Data.

PURPOSE: To evaluate the predictability of asphericity and average keratometry in patients with keratoconus after implantation of intrastromal corneal ring segments (ICRS) using artificial intelligence. METHODS: This study included 209 eyes of 160 patients with keratoconus (grades I, II, and III) who had ICRS implanted. The 160 arc length Ferrara ICRS was implanted in all patients. ICRS thickness varied from 150 to 250 µm. Pentacam (Oculus Optikgeräte, Wetzlar, Germany) corneal tomography parameters, clinical data, and ICRS data formed the basis of the 39 studied parameters. Linear regression was used to create the models. RESULTS: The best mean absolute error value found was 0.19 for asphericity and was 1.18 for mean keratometry. Comparing the mean absolute error values of the nomogram with the average absolute error of the algorithm, there was an improvement of 0.11 for asphericity and 0.09 for mean keratometry in relation to the current nomogram. CONCLUSIONS: The current study showed that the use of computational models could lead to more accurate results and contribute to better surgical decision-making to improve the clinical outcomes in patients with keratoconus implanted with ICRS. [J Refract Surg. 2018;34(8):547-550.].

Clinical Outcomes After Implantation of 320°-Arc Length Intrastromal Corneal Ring Segments in Keratoconus.

PURPOSE: To evaluate the clinical outcomes after implantation of a new 320°-arc length Ferrara intrastromal corneal ring segment (320-ICRS) in eyes of patients with keratoconus. METHODS: A multicentric nonrandomized study was conducted in which a new 320-ICRS was placed in 138 eyes of 130 patients with keratoconus. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), keratometry, corneal volume, asphericity, lines of vision gain/loss, and vectorial analysis were assessed preoperatively and at the final follow-up visit after the procedure. RESULTS: The mean follow-up time was 6.2 ± 3.3 (SD) months (range 3-12 months). Mean UDVA improved from 20/250 to 20/60. Mean CDVA improved from 20/100 to 20/40. Mean Q improved from -1.12 ± 0.49 preoperatively to -0.28 ± 0.51 postoperatively (P < 0.001). Mean corneal volume increased from 56.2 ± 4.28 mm preoperatively to 57.6 ± 4.74 postoperatively (P < 0.001). Mean Km reduced from 53.3 ± 5.5 D preoperatively to 47.8 ± 4.6 D postoperatively (P < 0.001). The change in UDVA, CDVA, and topographic astigmatism was statistically significant (P < 0.0001). CONCLUSIONS: The 320-ICRS can efficiently and safely improve visual acuity in keratoconus, modifying the corneal shape to a more physiologic, aspheric shape.

Clinical outcomes after implantation of a new intrastromal corneal ring with 140-degree of arc in patients with corneal ectasia.

AIM: To evaluate the clinical and tomographic outcomes after implantation of a new intrastromal corneal ring segment (ICRS) with 140-degrees of arc in eyes with corneal ectasia. METHODS: We evaluated patients with corneal ectasia implanted with Ferrara 140° ICRS from April 2010 to February 2015. Outcome measures included preoperative and postoperative corrected distance visual acuity (CDVA), keratometry simulated (K) reading, tomographic astigmatism and asphericity. All patients were evaluated using the Pentacam Scheimpflug system. RESULTS: The study evaluated 58 eyes. The mean follow-up was 16.81±10.8mo. The CDVA (logMAR) improved from 0.5±0.20 (20/60) to 0.3±0.21 (20/40) (P<0.01). The average K reduced from 49.87±7.01 to 47.34±4.90 D (P<0.01). The asphericity changed from -0.60±0.86 to -0.23±0.67 D (P<0.01). The mean preoperative tomographic astigmatism decreased from -8.0±3.45 to -4.53±2.52 D (P<0.01). CONCLUSION: The new ICRS model with 140-degrees of arc effectively improve the visual acuity and reduce the high astigmatism usually found in patients with corneal ectasia.

Intrastromal Corneal Ring Segments for Astigmatism Correction after Deep Anterior Lamellar Keratoplasty.

Background. To evaluate the change in corneal astigmatism after intrastromal corneal ring segment (ICRS) implantation in keratoconus patients with previous deep anterior lamellar keratoplasty (DALK). Design was a longitudinal, retrospective, interventional study. The study included 25 eyes of 24 patients with keratoconus who had DALK performed at least two years prior to ICRS implantation. All patients had a clear corneal graft with up to 8.00 D of corneal astigmatism and intolerance to contact lenses. The studied parameters were age, sex, corrected distance visual acuity (CDVA), maximum keratometry (K1), minimum keratometry (K2), spherical equivalent, and astigmatism. There was a statistically significant decrease in the postintervention analysis as follows: 3.5 D reduction in K1 (p < 0.001); 1.53 D in K2 (p = 0.005); and 2.52 D (p < 0.001) in the average K. The spherical equivalent reduced from -3.67 D (±2.74) to -0.71 D (±2.35) (p < 0.001). The topographic astigmatism reduced from 3.87 D preoperatively to 1.90 D postoperatively (p < 0.001). The CDVA improved from 0.33 (±0.10) to 0.20 (±0.09, p < 0.001). ICRS implantation is a useful option for the correction of astigmatism after DALK as it yields significant visual, topographic, and refractive results.

Tomographic Findings After Implantation of Ferrara Intrastromal Corneal Ring Segments in Keratoconus.

PURPOSE: To analyze and compare changes to the anterior and posterior corneal surfaces after Ferrara intracorneal ring segment (ICRS) (AJL, Boecillo, Spain) implantation and to correlate those changes with visual outcomes. METHODS: This retrospective case series study comprised consecutive patients with keratoconus implanted with the Ferrara ICRS. Computed tomography scans of the two corneal surfaces were obtained preoperatively and postoperatively with a rotating Scheimpflug imaging system. The Wilcoxon test was used to compare groups, and the Pearson's correlation coefficient was used to measure the strength of the correlation between variables. RESULTS: The study evaluated 241 eyes in 182 patients with keratoconus. Both corneal surfaces showed statistically significant decreases in average steep keratometry (K2) values, corneal astigmatism, elevation at the apex and at the thinnest point, maximum elevation in the central 4-mm area, and elevation inside the 3- and 4-mm zones and at the 3-mm ring. Regarding anterior surface parameters, a significant decrease was observed in flat keratometry (K1), whereas asphericity increased. On the posterior corneal surface, no significant changes in K1 and asphericity were observed. Poor correlation was found between visual outcomes and changes in tomographic parameters. The best correlation was obtained for anterior corneal astigmatism. CONCLUSIONS: ICRS implantation led to statistically significant changes in both anterior and posterior corneal surfaces. However, correlation between visual outcomes and tomographic parameters was poor. [J Refract Surg. 2017;33(2):110-115.].

Evaluation of anterior and posterior surfaces of the cornea using a dual Scheimpflug analyzer in keratoconus patients implanted with intrastromal corneal ring segments.

AIM: To evaluate corneal parameters measured with a dual Scheimpflug analyzer in keratoconus patients implanted with intrastromal corneal ring segments (ICRS). METHODS: Fifty eyes of 40 keratoconus patients had Ferrara ICRS implantation from November 2010 to April 2014. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refraction, keratometry, asphericity, elevation, pachymetry, root mean square (RMS), spherical aberration and coma were studied. All patients were evaluated using a dual Scheimpflug system. RESULTS: The mean follow-up time after the procedure was 12.7mo. The mean UCVA improved from 0.82 to 0.31 (P<0.001); the mean BCVA improved from 0.42 to 0.05 (P<0.0001), the mean spherical refraction changed from -3.06±3.80 D to -0.80±2.5 D (P<0.0001) and the mean refraction astigmatism reduced from -4.51±2.08 D to -2.26±1.18 D (P<0.0001). The changes from preoperative to postoperative, in parameters of the anterior and posterior surface of the cornea, were statistically significant except the elevation posterior at the apex of the cornea and posterior asphericity. CONCLUSION: The implantation of Ferrara ICRS induces changes in both anterior and posterior surfaces of the cornea.

Intrastromal corneal ring segments implantation in patients with keratoconus: 10-year follow-up.

PURPOSE: To evaluate the long-term safety and efficacy of Ferrara intrastromal corneal ring segments (ICRS) (Ferrara Ring; AJL, Boecillo, Spain) in patients with keratoconus. METHODS: The chart records of 36 eyes of 30 patients with keratoconus implanted with ICRS, operated on between July 1996 and January 2002, were retrospectively reviewed. The following parameters were studied: uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), keratometry (K), and central corneal thickness. The outcomes were evaluated at 5 and 10 years after ICRS implantation. RESULTS: The mean UDVA (logMAR) improved from 1.01 ± 0.28 (20/200 Snellen) to 0.71 ± 0.38 (20/100 Snellen) at 5 years (P < .05) and 0.67 ± 0.25 (20/90 Snellen) at 10 years (P = .735). The mean CDVA (logMAR) improved from 0.45 ± 0.45 (20/55 Snellen) to 0.24 ± 0.19 (20/35 Snellen) at 5 years (P < .05) and 0.29 ± 0.09 (20/38 Snellen) at 10 years (P = .292). The mean maximum K value decreased from 54.99 ± 6.33 to 50.58 ± 5.11 D at 5 years (P < .05) and 50.65 ± 5.17 D at 10 years (P = .854). The mean minimum K value decreased from 48.85 ± 5.70 to 46.90 ± 5.08 D at 5 years (P < .05) and 47.12 ± 4.22 D at 10 years (P = .945). The central corneal thickness decreased from 457.42 ± 58.21 to 421.34 ± 74.12 µm at 5 years (P = .039) and 434.32 ± 77.65 µm at 10 years (P = .427). CONCLUSIONS: Intrastromal corneal ring segments can effectively improve UDVA and CDVA 10 years after implantation in patients with keratoconus.

Femtosecond laser-assisted intrastromal corneal ring segment implantation for high astigmatism correction after penetrating keratoplasty.

PURPOSE: To assess the visual and refractive outcomes of femtosecond laser-assisted implantation of Ferrara-type intrastromal corneal ring segments (ICRS) in post-penetrating keratoplasty (PKP) eyes. SETTING: Instituto Oftalmológico Fernández-Vega, Oviedo, Spain. DESIGN: Cohort study. METHODS: Patients with previous PKP had ICRS implantation after femtosecond laser tunnel creation. The uncorrected (UDVA) and corrected (CDVA) distance visual acuities and residual refractive errors were recorded before and 6 months after ICRS implantation. The power vector method was used to analyze refractive errors preoperatively and postoperatively. RESULTS: This study enrolled 32 eyes of 30 patients. The mean UDVA (Snellen decimal) changed from 0.16 ± 0.15 (SD) preoperatively to 0.43 ± 0.28 postoperatively (P<.0001). Postoperatively, the UDVA was 20/40 or better in 40.6% of eyes. The mean CDVA was 0.67 ± 0.22 preoperatively and 0.80 ± 0.19 postoperatively (P<.0001). Postoperatively, the CDVA was better than 20/40 in 96.9% of eyes and 20/25 or better in 56.2% of eyes. By 6 months postoperatively, no eye had lost more than 2 lines of CDVA, 4 eyes lost 1 line, 6 eyes had no change, 9 eyes gained 1 line, and 13 eyes gained 2 or more lines. The safety index at 6 months was 1.20. The spherical equivalent and astigmatism components were significantly reduced after ICRS implantation (P<.04). CONCLUSION: Intrastromal corneal ring segment implantation using the femtosecond laser may be a good alternative for high astigmatism correction in post-PKP eyes.

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.

Intrastromal corneal ring segment implantation to correct astigmatism after penetrating keratoplasty.

PURPOSE: To evaluate the clinical outcomes of implantation of Ferrara intrastromal corneal ring segments (ICRS) in patients with astigmatism after penetrating keratoplasty (PKP). SETTING: Private clinic, Belo Horizonte, Brazil. DESIGN: Retrospective consecutive case series. METHODS: Chart records of post-PKP patients who had ICRS implantation from May 2005 to September 2009 were retrospectively reviewed. The following parameters were studied: corrected distance visual acuity (CDVA), keratometry (K) values, spherical equivalent (SE), spherical refractive error, corneal topographic astigmatism, minimum K, and maximum K. RESULTS: The study evaluated 59 eyes (54 patients). The mean CDVA (logMAR) improved from 0.45 ± 0.17 (SD) (range 0.18 to 1.00) to 0.30 ± 0.17 (range 0.00 to 1.00). The mean SE was -6.34 ± 3.40 diopters (D) (range 0.37 to -16.50 D) preoperatively and -2.66 ± 2.52 D (range 0.87 to -10.50 D) postoperatively. The mean spherical refractive error decreased from -7.10 ± 3.07 D (range 2.15 to 16.68 D) preoperatively to -3.46 ± 2.05 D (range 0.88 to 10.79 D) postoperatively. No patient lost visual acuity. The mean corneal topographic astigmatism decreased from 3.37 ± 1.51 D preoperatively to 1.69 ± 1.04 D postoperatively. The mean maximum K value decreased from 48.09 ± 2.56 D to 44.17 ± 2.67 D and the mean minimum K value, from 44.90 ± 2.54 D to 42.46 ± 2.63 D. All changes were statistically significant (P<.0001). CONCLUSION: Intrastromal corneal ring segments effectively reduced corneal cylinder in patients with astigmatism after PKP.

Intrastromal corneal ring segments: visual outcomes from a large case series.

BACKGROUND: To evaluate the clinical safety and efficacy of implanted Ferrara intrastromal corneal ring segments in a large sample of patients with ectatic corneal disease. DESIGN: Retrospective, consecutive case series. SAMPLES: A total of 1073 eyes of 810 patients consecutively operated from January 2006 to July 2008 were evaluated. METHODS: Two groups were created according to the type of ring implanted: Group 1 - patients implanted with the 160° of arc ring - and Group 2 - patients implanted with the 210° of arc ring. MAIN OUTCOME MEASURES: Uncorrected visual acuity, best-corrected visual acuity, keratometry, asphericity and pachymetry at the thinnest point of the cornea. All patients were evaluated using a corneal tomography (Pentacam, Oculus, Inc., Lynnwood, WA, USA). RESULTS: For Group 1 patients, uncorrected visual acuity increased to 20/80, best-corrected visual acuity increased to 20/40, asphericity decreased to -0.35, spherical equivalent decreased to -2.26 D and keratometry decreased to 45.72 D (P < 0.001 for each compared with preoperative values). For Group 2 patients, uncorrected visual acuity increased to 20/130, best-corrected visual acuity increased to 20/60, asphericity decreased to -0.56, spherical equivalent decreased to -4.14 D and keratometry decreased to 48.10 D (P < 0.001 for each compared with preoperative values). The 210° intrastromal corneal ring segments reduced keratometry and asphericity more than the 160° intrastromal corneal ring segments did. The complication rate was 3.82%. CONCLUSIONS: Ferrara intrastromal corneal ring segments implantation is safe and effective and has a low complication rate. It can effectively reduce the corneal steepening and improve uncorrected visual acuity and best-corrected visual acuity in patients with keratoconus.