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Aim To evaluate the changes in higher order aberrations (HOAs) after implantable collamer lens (ICL; Staar Surgical, Nidau, Switzerland) implantation. Methods Totally 30 eyes of 18 patients with myopia were included in this study with an average age of 25.77y (min: 21, max: 40). Refraction, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), HOAs (entire, corneal and internal) were evaluated preoperatively and three months postoperatively. Ocular aberrations were measured by using iTrace (Tracey Technology, Houston, Texas, USA). SPSS (IBM Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp) was used for the statistical analysis and the interpretation of the data. P values of less than 0.05 were considered statistically significant. Results The preoperative mean spherical power was -9.01 D (min: -5.00, max: -13.00) and the mean cylindrical error was -2.40 D (min: -0.50, max: -4.75). The postoperative mean residual spherical power was -0.73 D (min: -0.20, max: -1.75) and the mean cylindrical error was -0.89 D (min: -0.18, max: -2.09). Analyses were made on root mean square (RMS) values of total HOAs (tHOAs), spherical aberration, coma and trefoil as entire, corneal and internal components. The differences in entire tHOAs and in internal tHOAs were significant. There was no significant change found in spherical aberrations. The differences in entire coma and in internal coma were significant. There was no significant change found in corneal coma. With respect to trefoil, the only significant difference was in internal trefoil. Conclusion The ICL implantation corrects the refractive error successfully and changes entire and internal HOAs of the eye.

In the original publication, the Results paragraph of the abstract was published incorrectly. The correct version should read as follows.

Director, Refractive Surgery Department Dunya Eye Hospital Istanbul, Turkey. Laser Focus-Centre for Eye Microsurgery, 1KBC Zvezdara, Belgrade, Serbia. 3 Clinical Research Associate Refractive Surgery Department Dunya Eye Hospital Istanbul, Turkey. Chairman, Department of Ophthalmology, University Hospitals of Geneva, Switzerland. The first clinical results of collagen cross-linking in keratoconus were reported by a research group from Dresden University in 2003. In this study, 23 eyes of 22 patients with keratoconus were included and only one eye of each patient was treated except one case that was treated bilaterally. The follow-up period was from 3 to 47 (23,2 ± 12,9) months. The BCVA improved in 65% of the patients by an average of 1.26 lines. The refractive correction improved by an average of 1.14D. In 70% of the patients, maximum K was flattened by an average of 2.01D. K value remained stable in 5 patients and in 1 patient an increase of 0.28D was present. In 22% of the fellow control eyes, however maximum K value increased by an average of 1.48D. The same research group later published their long-term results in 2008 on 153 eyes of 111 patients. The minimal follow-up time was 12 months and the maximum follow-up was 7,5 years.

A thirty-nine year old man was referred to our institute due to progressive decreased visual acuity five years after bilateral Laser in situ Keratomileusis (LASIK). Topography revealed signs of post - LASIK ectasia. Patients' left eye was treated with simultaneous Topography Guided Photorefractive Keratectomy (PRK) followed by Corneal Collagen Cross Linking (CXL). Twelve months after the combined procedure both uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) showed significant improvement while topographic findings revealed an improvement of the astigmatic pattern. All higher order aberrations showed a significant decrease twelve months postoperatively. Combined topography guided PRK and corneal cross linking could represent an alternative treatment for post - LASIK ectasia.

Purpose To compare 2 sequences of combined intrastromal corneal ring segment (ICRS) implantation and ultraviolet/riboflavin–mediated corneal collagen crosslinking (CXL) in progressive keratoconus. Setting Dunya Eye Hospital, Istanbul, Turkey. Methods In this prospective comparative randomized consecutive study, CXL was followed by ICRS implantation (Group 1) or ICRS implantation was followed by CXL (Group 2). Uncorrected (UDVA) and corrected (CDVA) distance visual acuities, spherical equivalent (SE), manifest cylinder (cylinder), and mean keratometry (K) were compared preoperatively and postoperatively. Results The mean interval between treatments was 7 months ± 2 (SD) (mean follow-up, 13 ± 1 months). The mean UDVA and CDVA improved in both groups (UDVA: 0.07 ± 0.09 to 0.25 ± 0.12, Group 1, and 0.11 ± 0.09 to 0.32 ± 0.21, Group 2; CDVA: 0.24 ± 0.11 to 0.41 ± 0.20 and 0.22 ± 0.16 to 0.55 ± 0.2, respectively). The mean SE, cylinder, and mean K values decreased in both groups (SE: −7.13 ± 3.34 D to −2.98 ± 2.33 D, Group 1, and −7.05 ± 5.54 D to −2.81 ± 4.08 D, Group 2; cylinder: −4.38 ± 2.03 D to −2.62 ± 1.93 D and −4.68 ± 2.60 D to −2.20 ± 1.67 D, respectively; mean K: 52.47 ± 4.01 D to 48.31 ± 3.65 D and 52.06 ± 4.93 D to 48.08 ± 4.13 D, respectively). Overall, there was more improvement in CDVA, SE, and mean K in Group 2 than in Group 1. Conclusion Implantation of ICRS followed by CXL resulted in greater improvement of keratoconus.

PURPOSE To report the development of posterior linear stromal haze after simultaneous photorefractive keratectomy (PRK) followed by corneal collagen cross-linking (CXL). METHODS Combined simultaneous customized PRK followed by corneal collagen cross-linking was performed in 23 patients (28 eyes) with keratoconus. Corneas were examined biomicroscopically and by means of confocal microscopy before surgery and 1, 3, 6, 9, and 12 months after surgery. RESULTS Posterior linear stromal haze was observed clinically (slit lamp biomicroscopy) one month after surgery in 13 of 28 eyes (46.42%). No corneal edema or anterior haze formation was evident. Confocal microscopy revealed in those 13 eyes a hyperreflective area at the level of the posterior stroma 1 month after combined treatment. Both slit lamp examination and corneal confocal microscopy follow-up demonstrated a gradual anterior movement and a decrease in reflectance of this finding. At 12 months this posterior linear stromal haze, despite its anterior movement and decreased density, did not completely disappear at slit lamp and confocal microscopy analysis. CONCLUSIONS Posterior linear stromal haze formation may appear after simultaneous PRK followed by CXL in patients with keratoconus. This finding seems to gradually become less dense and slowly moves toward the anterior stroma.

Acta Ophthalmol. 2011: 89: 54–57 Abstract. Purpose: To report complications after the implantation of intrastromal corneal ring segments (Keraring; Mediphacos, Belo Horizonte, Brazil) in keratoconic eyes using a femtosecond laser (IntraLase; Advanced Medical Optics, Santa Ana, California, USA) for channel creation. Methods: Retrospective chart review of 531 patients (850 eyes) who underwent Keraring insertion using a femtosecond laser for channel creation. Intraoperative and postoperative complications were recorded. Results: Intraoperatively, there were 22 (2.7%) cases of incomplete channel formation. The rest of the intraoperative complications were galvo lag error (system malfunction) [five eyes (0.6%)], endothelial perforation [five eyes (0.6%)] and incorrect entry of the channel [two eyes (0.2%)]. Postoperatively, there were 11 (1.3%) cases of segment migration, two (0.2%) cases of corneal melting and one (0.1%) case of mild infection. The overall complication rate was 5.7% (49 cases out of 850 eyes). Conclusion: In this study, intracorneal ring segment implantation using a femtosecond laser for channel creation was related to a number of complications. The most common complications were incomplete channel creation (intraoperatively) and segment migration (postoperatively).

Purpose: To assess the progression of keratoconus in patients treated with collagen cross-linking with riboflavin and ultraviolet A (UVA) irradiation. Methods: Thirty-eight eyes of 19 patients with progressive keratoconus were enrolled in a prospective comparative study. Average follow-up was 9±2 months (range: 5 to 12 months). The worse eye was treated with collagen cross-linking, and the fellow eye served as the control. Corneal epithelium was mechanically removed. Riboflavin 0.1% solution in dextran T-500 20% solution was applied every 2 to 3 minutes for 30 minutes throughout the irradiation. Ultraviolet A irradiation (370 nm) was performed using a commercially available UVA lamp for 30 minutes. Results: The group treated with collagen cross-linking demonstrated a mean decrease (less myopic) in spherical equivalent refraction and cylinder of 1.03±2.22 diopters (D) (range: −5.25 to +3.75 D) and 1.04±1.44 D (range: −2.00 to +4.00 D), respectively ( P P P =.06) and endothelial cell count ( P =.07). The untreated group showed no statistical difference for any of the clinical parameters, apart from UCVA and BSCVA, which decreased by 0.08±0.12 (range: −0.40 to 0.10) and 0.06±0.09 (range: −0.20 to 0.10), respectively ( P Conclusions: Riboflavin/UVA collagen cross-linking appears to be efficacious in inhibiting the progression of keratoconus by reducing the corneal curvature, spherical equivalent refraction, and refractive cylinder in eyes with progressive keratoconus at average 9-month follow-up. [ J Refract Surg . 2009;25:371–376.]

Keratoconus is a condition characterized by biomechanical instability of the cornea, presenting in a progressive, asymmetric and bilateral way. Corneal collagen cross-linking with riboflavin and UVA (CXL) is a new technique of corneal tissue strengthening that combines the use of riboflavin as a photo sensitizer and UVA irradiation. The studies showed that CXL was effective in halting the progression of keratoconus over a period of up to four years. The published studies also revealed a reduction of max K readings by more than 2 D, while the postoperative SEQ was reduced by an average of more than 1 D, and refractive cylinder decreased by about 1 D. No eyes lost any line of BCDVA. Moreover, there was no significant decrease in endothelial cell density. It was also found that CXL treatment was effective with reducing corneal and total wavefront aberrations. Corneal cross-linking has also led to an arrest and/or even a partial reversal of keratectasia in the treatment of iatrogenic ectasia after excimer laser ablation. A primary intervention such as CXL should be considered to potentially increase the biomechanical stability of the corneal tissue and postpone the need of lamellar or penetrating keratoplasty.