A. John Kanellopoulos

Stability of simultaneous topography-guided photorefractive keratectomy and riboflavin/UVA cross-linking for progressive keratoconus: case reports.

PURPOSE To follow the stability of a simultaneously delivered therapy that corrects aberrations and stiffens the corneal collagen of eyes with progressive keratoconus. METHODS Two patients with progressive keratoconus underwent partial treatment (70% cylinder and sphere up to 50-μm central depth) with topographic customized photorefractive keratectomy (PRK) using the T-CAT module of the ALLEGRETTO WAVE Eye-Q excimer laser (Alcon Laboratories Inc), and then immediate corneal collagen cross-linking (CXL) with riboflavin 0.1% drops every 2 minutes while exposed to mean 365-nm ultraviolet A (UVA) light at 3.0 mW/cm² for 30 minutes (the Athens Protocol). Pre- and postoperative evaluations included manifest and cycloplegic refraction, Scheimpflug corneal tomography and pachymetry, and slit-lamp examination of corneal clarity with a minimum follow-up of 30 months. RESULTS Both treated eyes experienced rapid healing of the epithelial surface within 5 days and progressive improvement of vision. In the first case, partial treatment reduced the astigmatism and aberrations, allowing for successful soft contact lens wear at 3 months. Follow-up at 13, 19, 30, and 36 months showed progressive reduction of refractive myopia and keratometric power. In the second case, laser treatment led to a near emmetropic refraction with an uncorrected visual acuity of 20/20 at 3 months, which remained unchanged at 21 and 30 months postoperative. CONCLUSIONS Partial topography-guided PRK followed by riboflavin/UVA CXL is a safe and effective therapy that halts the progression of keratoectasia and reduces the spherocylindrical refraction and aberrations to improve the visual function of patients with progressive keratoconus. Stability and progressive improvement over time is observed, although limitations may exist for steeper and thinner corneas.

Measurement of angle kappa with synoptophore and Orbscan II in a normal population.

PURPOSE To obtain normative values of angle kappa in a normal population by synoptophore and Orbscan II and to compare the reliability of these devices. METHODS Three hundred consecutive healthy individuals were enrolled in the study. A complete orthoptic and ophthalmologic examination was performed. Synoptophore and Orbscan II corneal topography were used to measure angle kappa. To evaluate the association of the angle kappa and refraction measures, individuals were further classified according to the degree of myopia and hyperopia. The spherical equivalent error measures were grouped into six categories: > or = -3.00 diopters (D); -2.75 to -1.50 D; -1.25 to -0.50 D; +0.50 to +1.25 D; +1.50 to +2.75 D; and > or = +3.00 D. Paired t test and Pearsons correlation test were used for statistical analysis. RESULTS The mean age of the individuals was 28.74 +/- 1.63 years (range: 20 to 40 years). The angle kappa values obtained by synoptophore and Orbscan II were normally distributed. In the myopic group, angle kappa values decreased significantly towards negative refractive errors. In contrast, a correlation existed between large positive angles and positive refractive errors in the hyperopic group. Angle kappa values obtained by Orbscan II were significantly higher in all groups when compared to synoptophore (P < .0001). A significant correlation was noted between synoptophore and Orbscan II measurements (r = 0.932, P < .0001). CONCLUSIONS A significant correlation exists between positive refractive errors and large positive angle kappa values. Refractive surgeons must take into account angle kappa, especially in hyperopic patients, to avoid complications related to decentration of the ablation zone.

Introduction of quantitative and qualitative cornea optical coherence tomography findings induced by collagen cross-linking for keratoconus: a novel effect measurement benchmark

Purpose To introduce a novel, noninvasive technique to determine the depth and extent of anterior corneal stroma changes induced by collagen cross-linking (CXL) using quantitative analysis of high-resolution anterior-segment optical coherence tomography (OCT) post-operative images. Setting Private clinical ophthalmology practice. Patients and methods Two groups of corneal cross-sectional images obtained with the OptoVue RTVue anterior-segment OCT system were studied: group A (control) consisted of unoperated, healthy corneas, with the exception of possible refractive errors. The second group consisted of keratoconic corneas with CXL that were previously operated on. The two groups were investigated for possible quantitative evidence of changes induced by the CXL, and specifically, the depth, horizontal extent, as well as the cross-sectional area of intrastromal hyper-reflective areas (defined in our study as the area consisting of pixels with luminosity greater than the mean +2 × standard deviation of the entire stromal cross section) within the corneal stroma. Results In all images of the second group (keratoconus patients treated with CXL) there was evidence of intrastromal hyper-reflective areas. The hyper-reflective areas ranged from 0.2% to 8.8% of the cross-sectional area (mean ± standard deviation; 3.46% ± 1.92%). The extent of the horizontal hyper-reflective area ranged from 4.42% to 99.2% (56.2% ± 23.35%) of the cornea image, while the axial extent (the vertical extent in the image) ranged from 40.00% to 86.67% (70.98% ± 7.85%). There was significant statistical difference (P < 0.02) in these values compared to the control group, in which, by application of the same criteria, the same hyper-reflective area (owing to signal noise) ranged from 0.00% to 2.51% (0.74% ± 0.63%). Conclusion Herein, we introduce a novel, noninvasive, quantitative technique utilizing anterior segment OCT images to quantitatively assess the depth and cross-sectional area of CXL in the corneal stroma based on digital image analysis. Mean cross-sectional area showing evidence of CXL was 3.46% ± 1.92% of a 6 mm long segment.

Wavefront-guided Enhancements Using the WaveLight Excimer Laser in Symptomatic Eyes Previously Treated With LASIK

PURPOSE To describe our clinical experience in wavefront-guided LASIK enhancements using the WaveLight ALLEGRETTO system (WaveLight Technologie AG, Erlangen, Germany) for symptomatic eyes previously treated with standard LASIK. METHODS Twenty-six eyes of 20 patients with residual myopia, hyperopia, or mixed astigmatism and/or night vision symptoms after primary standard LASIK were considered for wavefront-guided customized retreatment using the WaveLight ALLEGRETTO WAVE 200 Hz excimer laser system (model 106). Preoperative best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity, topography with the ALLEGRETTO Topolyzer, wavefront analysis using the ALLEGRETTO WAVE Tscherning Analyzer, and contrast sensitivity were compared to postoperative (enhancement) measurements. RESULTS Twenty-two of the original 26 eyes underwent wavefront-guided enhancement, 4 were excluded because they did not meet wavefront-guided treatment inclusion guidelines of this study. Mean follow-up was 8 months (range: 6 to 13 months, standard deviation [SD] 2). All patients were within +/- 0.50 diopters (manifest refraction) of intended postoperative refraction. The mean preoperative BSCVA improved from 20/25 (SD +/- 0.12) to 20/18 (SD +/- 0.1) postoperatively. All patients gained at least one line of BSCVA, and a maximum of three lines. There was no loss of BSCVA in any patient. The total amount of high order aberrations (RMSH) decreased from an average of 1.04 (SD +/- 0.22) to 0.46 (SD +/- 0.14) microm. Patients also had a mean improvement in low contrast sensitivity of 59%. CONCLUSIONS Based on this small series, customized wavefront-guided enhancements using the WaveLight ALLEGRETTO system in patients who underwent previous LASIK appear to be safe and effective in correcting residual refractive error, reducing high order aberrations, and improving visual symptoms when reliable and reproducible measurements are achieved.

Topography-guided custom retreatments in 27 symptomatic eyes.

PURPOSE To evaluate the use of topography-guided ablations for refractive irregularities induced by previous surgery. METHODS This prospective, non-comparative trial comprised 27 symptomatic eyes with a history of LASIK for myopia that underwent topography-guided treatment with the ALLEGRETTO WAVE system. Pre- and postoperative refraction, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), corneal asphericity (Q value), low contrast sensitivity, and patients subjective assessment of improvement were measured. RESULTS Preoperative data were sphere -0.84 +/- 1.37 diopters (D), cylinder -1.55 +/- 0.78 D, UCVA 20/49 +/- 0.22, BSCVA 20/32 +/- 0.15, and Q value 1.46 +/- 0.79. Postoperative data at mean 6-month follow-up were: sphere -0.61 +/- 0.81 D, cylinder -0.53 +/- 0.58 D, UCVA 20/25 +/- 0.21 (P < .01), BSCVA 20/21 +/- 0.14 (P < .001), and Q value 1.07 +/- 0.89. Contrast sensitivity scores improved by 70%. No loss of BSCVA occurred in any patient. CONCLUSIONS Topography-guided treatments may be effective in correcting the quality of vision. It should be viewed as a possible two-step procedure due to spherical adjustment that may change refraction unpredictably.

LASIK for Hyperopia With the WaveLight Excimer Laser

PURPOSE To evaluate the safety and efficacy of the ALLEGRETTO WAVE excimer laser system (WaveLight Laser Technologie AG, Erlangen, Germany) in LASIK for hyperopia and hyperopic astigmatism. METHODS One hundred twenty consecutive LASIK cases for hyperopia with or without astigmatism treated with the ALLEGRETTO WAVE excimer laser were prospectively evaluated up to 12 months postoperatively. Patients were allocated into three groups according to their refractive sphere and cylinder: a low hyperopia group, with up to +3.00 diopters (D) sphere and astigmatism < or = +1.00 D (n = 52); a moderate hyperopia group with +3.25 to +5.00 D sphere and astigmatism of < or = +1.00 D (n = 45); and a high hyperopia/toric group with sphere > or = +5.25 D or cylinder > or = +1.25.D (n = 23). Flaps were created with the Moria M2 microkeratome (Moria, Antony, France). Parameters evaluated were pre- and postoperative refractive error, uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), higher order aberration change, and contrast sensitivity. RESULTS One hundred twelve eyes (93%) were available for follow-up at 12 months. Of the eyes in the low hyperopia group, 92% were within +/- 0.50 D of the refractive goal. For the moderate sphere group and the high hyperopia/toric group, 79% and 71% of eyes, respectively, were within +/- 0.50 D of the refractive goal. No eye lost > or = 2 lines of BSCVA. An increase in higher order aberrations was noted in the high hyperopia/toric group from 0.47 microm (+/- 0.096) to 0.94 microm (+/- 0.167) (P < .001). No significant changes in higher order aberrations were noted in the low and moderate hyperopia groups. CONCLUSIONS Hyperopic LASIK using the WaveLight ALLEGRETTO WAVE excimer laser appears to be safe and effective in the correction of low, moderate, and high hyperopia and hyperopic astigmatism.

Three-dimensional LASIK flap thickness variability: topographic central, paracentral and peripheral assessment, in flaps created by a mechanical microkeratome (M2) and two different femtosecond lasers (FS60 and FS200)

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Long-term bladeless LASIK outcomes with the FS200 Femtosecond and EX500 Excimer Laser workstation: the Refractive Suite

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Digital analysis of flap parameter accuracy and objective assessment of opaque bubble layer in femtosecond laser-assisted LASIK: a novel technique

Background: The purpose of this study was to determine flap parameter accuracy, extent of the opaque bubble layer, and incidence of skip lines in femtosecond laser-assisted stromal in situ keratomileusis (LASIK) using the WaveLight® FS200 laser and optoelectronic clinical measurements. Methods: Images from 101 flaps were automatically recorded during consecutive routine LASIK procedures performed using the WaveLight FS200 femtosecond laser and the EX500 excimer laser. Digital processing of these images was used to evaluate objectively the diameter of FS200-created flaps, by comparing planned versus achieved procedures and to evaluate the incidence and extent (area) of the opaque bubble layer. Results: The intended flap diameters were between 8.00 mm and 9.50 mm. The achieved flap diameters showed extremely high precision, and were on average −0.16 ± 0.04 mm smaller for a 8.00 mm intended flap diameter, −0.12 ± 0.03 mm smaller for a 8.50 mm flap, and up +0.06 ± 0.06 mm wider for a 9.50 mm flap. With an average flap area of 72.4 mm2, the mean area of the opaque bubble layer (4.1 ± 4.3 [range 0–14.34] mm2) corresponded to a 6% opaque bubble layer-to-flap area. Specifically, 80% of the femtosecond-created flaps had an essentially zero opaque bubble layer (<2.7% of the flap area). Conclusion: In our clinical experience, flaps created using FS200 and this novel highly objective assessment technique demonstrate both precision and reproducibility. The incidence of opaque bubble layer was minimal.

Anterior Segment Optical Coherence Tomography: Assisted Topographic Corneal Epithelial Thickness Distribution Imaging of a Keratoconus Patient

Purpose: To evaluate safety, efficacy and ease of measurement of epithelial thickness in a keratoconic patient based on anterior segment optical coherence tomography (AS-OCT). Methods: A 25-year-old male patient, previously diagnosed with keratoconus, with highly asymmetric manifestation among the two eyes, was subjected to AS-OCT corneal epithelial imaging. We investigated epithelial thickness and epithelial topographic thickness distribution. Results: Mean epithelial thickness was 51.97 ± 0.70 for the less affected right eye (OD), and 55.65 ± 1.22 for the more affected left eye (OS). Topographic epithelial thickness variability for the OD was 1.53 ± 0.21 μm, while for the OS it was 9.80 ± 0.41 μm. Conclusions: This case further supports our previous findings with high-frequency ultrasound measurements of the increase in overall epithelial thickness in keratoconic eyes in comparison with normal eyes. AS-OCT further offers ease of use and possibly higher predictability of measurement. This case report, based on AS-OCT imaging, verifies increased overall epithelial thickness in keratoconic eyes, as introduced by a previous study [Kanellopoulos et al.: Clin Ophthalmol 2012;6:789-800], based on high-frequency scanning ultrasound biomicroscopy imaging.