Correction to: Visual, refractive and topographic outcomes of progressive thickness intrastromal corneal ring segments for keratoconic eyes.

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

Visual, refractive and topographic outcomes of progressive thickness intrastromal corneal ring segments for keratoconic eyes.

PURPOSE: To evaluate one-year visual, refractive, and topographic outcomes of 58 eyes of 53 keratoconus patients who underwent surgery with a progressive thickness intrastromal corneal ring segment (ICRS). METHODS: This multi-center, retrospective, observational study evaluates the one-year effects of progressive thickness ICRS implanted in keratoconus patients meeting the inclusion criteria. One or two progressive ICRS were implanted in the selected eyes after creating an intrastromal tunnel with a femtosecond laser. Pre- and postoperative uncorrected distance visual acuity, best-corrected distance visual acuity, manifest refraction (both spherical equivalent and cylindrical refractions), corneal astigmatism, maximum keratometry, corneal thickness, and corneal topography measurements and indices were evaluated. RESULTS: In this retrospective case series, 58 eyes of 53 keratoconus patients were included with a follow-up of 12 months. The mean age was 30.89 ± 11.90 years. There were improvements postoperatively in mean values of visual acuities, both uncorrected from 0.71 (preoperatively) to 0.28 (log MAR), and best-corrected from 0.28 to 0.10 (log MAR), mean cylindrical refraction from - 2.35 ± 1.51 to - 4.15 ± 2.23 D, and mean spherical equivalent from - 2.10 ± 2.25 to - 4.64 ± 3.2 D. There was also a reduction in maximal keratometry from 54.21 D preoperatively to 50.93 D postoperatively. CONCLUSION: The implantation of the progressive thickness ICRS is an effective and safe method to improve the vision of keratoconic eyes. Corneal stability was maintained at the 12-month mark.

The effects of implantable collamer lens implantation on higher order aberrations.

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.

Four-Stage Procedure for Keratoconus: ICRS Implantation, Corneal Cross-linking, Toric Phakic Intraocular Lens Implantation, and Topography-Guided Photorefractive Keratectomy.

PURPOSE: To evaluate a four-stage combined treatment for keratoconus including intrastromal corneal ring segment (ICRS) implantation followed by corneal cross-linking (CXL), toric phakic intraocular lens (IOL) implantation, and topography-guided photorefractive keratectomy (TG-PRK). METHODS: In this retrospective interventional case series, 11 eyes of 7 patients with progressive keratoconus were treated with a four-stage procedure including the following: Keraring ICRS (Mediphacos Ltda, Belo Horizonte, Brazil) implantation followed by CXL, phakic IOL implantation, and TG-PRK (minimum 6 months between each stage). Minimum follow-up was 12 months after TG-PRK. RESULTS: Both mean uncorrected distance visual acuity and corrected distance visual acuity (CDVA) improved from 0.025 decimal (20/800 Snellen) and 0.093 decimal (20/215 Snellen) preoperatively to 0.68 decimal (20/30 Snellen) and 0.73 decimal (20/27 Snellen), respectively, after the combined treatment (P < .0001). Mean postoperative CDVA of 0.73 decimal (20/27 Snellen) was similar to preoperative contact lens CDVA of 0.72 decimal (20/28 Snellen). Mean manifest refraction spherical equivalent reduced from 16.78 ± 3.58 to 0.59 ± 0.89 diopters (P < .0001) and mean refractive astigmatism reduced from 5.16 ± 1.86 to 0.82 ± 0.28 diopters (P < .0001). CONCLUSIONS: This four-stage procedure appears to be an effective and safe approach for corneal stabilization and improvement of functional vision in patients with keratoconus. Larger case series with a longer follow-up are required to thoroughly evaluate the efficacy, safety, and stability of this combined approach. [J Refract Surg. 2017;33(10):683-689.].

Refractive Outcomes of 20 Eyes Undergoing ICL Implantation for Correction of Hyperopic Astigmatism.

PURPOSE: To analyze 1-week, 1-month, and 12-month postoperative refractive outcomes of eyes that under-went ICL implantation to correct hyperopic astigmatism. METHODS: The study enrolled 20 eyes of patients with an average age of 32 years (range: 21 to 40 years). The outcomes of spherical and cylindrical refraction, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), vault, and angle parameters were evaluated 1 week, 1 month, and 12 months postoperatively. RESULTS: The preoperative mean UDVA was 0.15 ± 0.11 (decimal) (20/133 Snellen) and increased to 0.74 ± 0.25 (20/27 Snellen) postoperatively, with a change of 0.59 (decimal) (20/33.9 Snellen) (P < .0001), which was statistically significant. The preoperative mean CDVA was 0.74 ± 0.25 (decimal) (20/27 Snellen) and increased to 0.78 ± 0.21 (20/25 Snellen), with a change of 0.03 (decimal) (20/666 Snellen) (P < .052), which was not statistically significant. The mean preoperative sphere was 6.86 ± 1.77 diopters (D) and the mean preoperative cylinder was -1.44 ± 0.88 D. The mean 12-month postoperative sphere decreased to 0.46 ± 0.89 D (P < .001) and cylinder decreased to -0.61 ± 0.46 D (P < .001), with a change of 6.40 D, both of which were statistically significant. The mean 1-month postoperative vault was 0.65 ± 0.13 mm and decreased to 0.613 ± 0.10 mm at 1 year postoperatively, with a change of 0.44 mm (P < .003). The preoperative/12-month and 1-month/12-month trabecular-iris angle (TIA), trabecular-iris space area 500 mm from the scleral spur (TISA500), and angle opening distance 500 mm from the scleral spur (AOD500) values were analyzed nasally, temporally, and inferiorly. All differences were statistically significant between preoperative/12-month analysis. The only differences between 1- and 12-month analysis were on TISA500 inferior (P < .002) and AOD500 nasal (0.031) values. CONCLUSIONS: ICL hyperopic toric implantation is a safe method and provides stable refractive outcomes in patients with high hyperopia (up to 10.00 D) and astigmatism (up to 6.00 D). [J Refract Surg. 2017;33(9):604-609.].

Optical Measurement of Straylight in Eyes With Cataract.

PURPOSE: To measure straylight in a cohort of patients with cataract using a novel optical instrument and to correlate optical straylight values with clinical grade of cataracts and psychophysical straylight values. METHODS: Measurements were performed on 53 eyes of 44 patients with cataract admitted to the ophthalmology service of the university hospital in Murcia, Spain, and 9 young volunteers with no known ophthalmic pathology. Lens opacities were classified according to the Lens Opacities Classification System Ill (LOCS III) under slit-lamp examination. Intraocular straylight was additionally assessed psychophysically using the C-Quant straylight meter (Oculus Optikgeräte GmbH, Wetzlar, Germany). RESULTS: Optical measurements of the logarithm of the straylight parameter ranged from 1.01 to 2.01 (mean: 1.43 ± 0.244) in patients with cataract and 0.80 to 1.08 (mean: 0.92 ± 0.104) in healthy young volunteers. Straylight differed by a statistically significant amount among different LOCS III groups (P < .05). Moreover, the optically measured straylight parameter was positively correlated to the psychophysically estimated value (r = 0.803, P < .05). CONCLUSIONS: A new compact optical instrument suitable for clinical measurements of straylight in the human eye has been developed. Optically measured straylight values were highly correlated to those that were obtained psychophysically. Optical measurement of straylight can be used for the objective classification of cataract opacities based on their optical impact. [J Refract Surg. 2016;32(12):846-850.].

Compact optical integration instrument to measure intraocular straylight.

Optical measurement of straylight in the human eye is a challenging task. Issues such as illumination geometry, detector sensitivity and dynamic range as well as various inherent artifacts must be addressed. We developed a novel instrument based on the principle of double-pass optical integration adapted for fast measurements in a clinical setting. The experimental setup was validated using four different diffusers introduced in front of the eyes of ten subjects. Measurement limitations and future implications of rapid optical measurement of straylight in ophthalmic diagnosis are discussed.