Faculty Bibliography

Purpose: To implement digital analysis of pupil imaging (shape and size) in relation to cornea apex position and compare preoperative and postoperative data to measure the possible pupil shape and centration changes following cataract surgery. Methods: 35 consecutive cataract patients (70 eyes) were digitally imaged pre- and post-operatively by Placido Topography (Vario Topolyzer, WaveLight, Erlagen, Germany) providing pupil imaging and cornea apex identification. Digital analysis implemented on the images investigated the Cartesian coordinates (nasal -temporal being the horizontal, and superior-inferior the vertical axis) of the corneal apex (approximating the intersection of line of sight with the cornea) to the pupil geometric center (approximating the visual axis). The Cartesian changes of the differences were associated with postoperative pupil centroid shift. Results: The photopic pupil measurements indicated a pre-operative temporal location of 0.24 +/- 0.15 (0.03 to 0.44) mm and a superior of 0.01+/-0.14 (-0.22 to +0.18) mm. Postoperatively, the pupil center appeared shifted temporally by 0.15 +/- 0.12 (0.27 to -0.01) mm and superiorly by +0.06 +/- 0.21 (-0.33 to 0.22) mm. The scotopic pupil measurements were preoperatively temporally by 0.28 +/- 0.15 (0.41 to 0.03) mm, and inferiorly by 0.02 +/- 0.20 (-0.24 to 0.29) mm. Postoperatively the pupil center was temporally by 0.20 +/- 0.10 (0.04 to 0.28) mm and superiorly by 0.04 +/- 0.19 (-0.26 to +0.27) mm. Conclusions: Cataract extraction surgery appears to affect pupil centration. Specifically a more nasal (+0.10 mm) and more superior (0.05 mm) shift was recorded. These data may have clinical reference in targeted intraoperative IOL centration

PURPOSE: The aim of this study was to evaluate via Fourier-domain anterior-segment optical coherence tomography 3-dimensional corneal, epithelial, and graft thickness changes after Descemet stripping automated endothelial keratoplasty (DSAEK). METHODS: Sixteen eyes were investigated preoperatively and up to 6 months postoperatively for preoperative and postoperative central corneal thickness (CCT), minimum corneal thickness, central graft thickness (CGT), and for epithelial topographic thickness variability. An age-matched and gender-matched control group of 32 healthy eyes was used for comparison. RESULTS: In the DSAEK group, the preoperative CCT was 582.32 +/- 45.24 (550-615) mum. One-month postoperatively, the CCT was 736.26 +/- 34.52 (713-771) mum, and the CGT was 210.42 +/- 34.52 (145-243) mum. Three months postoperatively, the CCT was 641.39 +/- 38.75 (569-684) mum, and the CGT was 171.23 +/- 27.54 (119-185) mum. The preoperative center epithelial thickness was 55.74 +/- 9.29 (45-74) mum, the minimum was 32.53 +/- 14.30 (13-53) mum, the maximum was 76.00 +/- 11.32 (64-105) mum, and the topographic thickness variability was 10.84 +/- 4.09 (5.90-18.80) mum. Three months postoperatively, the center epithelial thickness was 47.21 +/- 5.45 (43-56) mum, the minimum was 35.11 +/- 4.70 (30-41) mum, the maximum was 58.11 +/- 6.51 (49-65) mum, and the topographic variability was 4.77 +/- 1.48 (2.90-6.50) mum. The average differences were -8.53, +4.53, and -17.89 mum for the center, minimum, and maximum (P < 0.001, <0.001, and <0.001). Similar results were obtained 3 and 6 months postoperatively. CONCLUSIONS: We present a near-term postoperative investigation of the corneal and epithelial thickness changes after DSAEK for bullous keratopathy, by in vivo, clinical anterior-segment optical coherence tomography. Epithelial thickness recovery and normalization and corneal deturgescence were noted as early as in the first postoperative month.

Purpose To evaluate applicability of spectral domain optical coherence tomography (AS-OCT) of epithelial thickness patterns in normal and in the diagnosis of keratoconus, and to compare with Scheimpflug imaging keratoconus severity. Methods 250 healthy (control group-A) and 155 untreated keratoconic (study group-B) eyes were subjected to anterior segment OCT three-dimensional epithelial thickness imaging. Comparative statistical analysis of patterns was performed, investigating central, minimum, inferior, posterior, and topographic variability of epithelial thickness. Epithelial thickness characteristics were correlated to established Scheimpflug imaging-derived keratoconus classification and anterior surface irregularity indices. Results Intra-individual repeatability of epithelial thickness was for group-A +/-1.13 mum, for group-B +/-1.78 mum for center and average +/-1.67 mum (center, superior, inferior, maximum and minimum). In group-A, center epithelial was 52.54+/-3.23 mum, maximum 55.33+/-3.27 mum and minimum 48.50+/-3.98 mum. In group B, center thickness was 51.75+/-7.02 mum, maximum and minimum were 63.54+/-8.85 mum and 40.73+/-8.51 mum. Topographic variability was 6.07+/-3.55 mum (range -22.81+/-12.55 mum) for the keratoconic group-B, while for the control group-A 1.59+/-0.79 mum (-6.86+/-3.33 mum). Epithelial thickness topographic variability and range correlated well with keratoconus severity in the study group-B. Conclusions AS-OCT may o er high predictability of 3 dimensional epithelial assessment in keratoconus. Overall epithelial thickness in keratoconic eyes appears significantly different to normal even in lower stages of keratoconus. Increased overall thickness correlated remarkably with keratoconus severity, as defined by established Scheimpflug imaging-derived anterior-surface irregularity indices

PURPOSE/OBJECTIVE:To evaluate epithelial thickness profile changes following myopic femtosecond laser-assisted LASIK in relation to the degree of myopia corrected, evaluated with a spectral-domain anterior-segment optical coherence tomography system. METHODS:Sixty-one consecutive cases were observed for corneal epithelial thickness distribution preoperatively and at 1 day, 1 week, 1 month, and 1 year postoperatively. Epithelial thickness mapping was obtained with a spectral-domain optical coherence tomography system (Optovue Inc., Fremont, CA). Descriptive statistics investigated epithelial thickness at the central 2-mm area, the mean over the central 6-mm area, and mid-peripherally at the 5-mm ring area. RESULTS:Preoperatively, the pupil center epithelial thickness was 51.67 ± 2.57 μm (range: 45 to 56 μm), mean was 51.76 ± 2.66 μm (range: 45 to 57 μm), and mid-periphery was 51.78 ± 2.71 μm (range: 46 to 57 μm). Compared to the preoperative values, the epithelial thickness for the center, mean, and mid-periphery was −0.30, +1.07, and +1.35 μm at 1 week, +1.58, +2.88, and +3.31 μm at 1 month (P = .0036, < .001, and < .001), and +1.42, +2.90, and +3.19 μm at 1 year postoperatively (P = 0.146, < .001, and < .001), respectively. The correlation analysis between the epithelial thickness increase and the spherical equivalent of myopic correction showed a trend toward epithelial thickness increase with the amount of myopic ablation, particularly at the mid-peripheral 5-mm area. CONCLUSIONS:In this comprehensive study of postoperative corneal epithelial thickness remodeling following femtosecond laser-assisted myopic LASIK correction, an increase at the 1-month and up to 1-year postoperative interval suggested postoperative epithelial activity in connection to the extent of ablation.

PURPOSE/OBJECTIVE:To investigate refractive, topometric, pachymetric, and visual rehabilitation changes induced by anterior surface normalization for keratoconus by partial topography-guided excimer laser ablation in conjunction with accelerated, high-fluence cross-linking. METHODS:Two hundred thirty-one keratoconic cases subjected to the Athens Protocol procedure were studied for visual acuity, keratometry, pachymetry, and anterior surface irregularity indices up to 3 years postoperatively by Scheimpflug imaging (Oculus Optikgeräte GmbH, Wetzlar, Germany). RESULTS:Mean visual acuity changes at 3 years postoperatively were +0.38 ± 0.31 (range: -0.34 to +1.10) for uncorrected distance visual acuity and +0.20 ± 0.21 (range: -0.32 to +0.90) for corrected distance visual acuity. Mean K1 (flat meridian) keratometric values were 46.56 ± 3.83 diopters (D) (range: 39.75 to 58.30 D) preoperatively, 44.44 ± 3.97 D (range: 36.10 to 55.50 D) 1 month postoperatively, and 43.22 ± 3.80 D (range: 36.00 to 53.70 D) up to 3 years postoperatively. The average Index of Surface Variance was 98.48 ± 43.47 (range: 17 to 208) pre-operatively and 76.80 ± 38.41 (range: 7 to 190) up to 3 years postoperatively. The average Index of Height Decentration was 0.091 ± 0.053 μm (range: 0.006 to 0.275 μm) preoperatively and 0.057 ± 0.040 μm (range: 0.001 to 0.208 μm) up to 3 years postoperatively. Mean thinnest corneal thickness was 451.91 ± 40.02 μm (range: 297 to 547 μm) preoperatively, 353.95 ± 53.90 μm (range: 196 to 480 μm) 1 month postoperatively, and 370.52 ± 58.21 μm (range: 218 to 500 μm) up to 3 years postoperatively. CONCLUSIONS:The Athens Protocol to arrest keratectasia progression and improve corneal regularity demonstrates safe and effective results as a keratoconus management option. Progressive potential for long-term flattening validates using caution in the surface normalization to avoid overcorrection.

PURPOSE: To evaluate in vivo epithelial thickness in dry eye by anterior segment optical coherence tomography. DESIGN: Observational, retrospective case-control study. METHODS: Two age-matched groups of female subjects, 70 eyes each, age approximately 55 years, were studied in clinical practice setting: a control (unoperated, no ocular pathology) and a dry eye group (clinically confirmed dry eye, unoperated and no other ocular pathology). Corneal epithelium over the entire cornea was topographically imaged via a novel anterior segment optical coherence tomography (AS-OCT) system. Average, central, and peripheral epithelial thickness as well as topographic epithelial thickness variability were measured. RESULTS: For the control group, central epithelial thickness was 53.0 +/- 2.7 mum (45-59 mum). Average epithelium thickness was 53.3 +/- 2.7 mum (46.7-59.6 mum). Topographic thickness variability was 1.9 +/- 1.1 mum (0.7-6.1 mum). For the dry eye group, central epithelial thickness was 59.5 +/- 4.2 mum (50-72 mum) and average thickness was 59.3 +/- 3.4 mum (51.4-70.5 mum). Topographic thickness variability was 2.5 +/- 1.5 mum (0.9-6.9 mum). All pair tests of respective epithelium thickness metrics between the control and dry eye group show statistically significant difference (P < .05). CONCLUSIONS: This study, based on very user-friendly, novel AS-OCT imaging, indicates increased epithelial thickness in dry eyes. The ease of use and the improved predictability offered by AS-OCT epithelial imaging may be a significant clinical advantage. Augmented epithelial thickness in the suspect cases may be employed as an objective clinical indicator of dry eye.

PURPOSE: To investigate epithelial thickness-distribution characteristics in a large group of keratoconic patients and their correlation to normal eyes employing anterior-segment optical coherence tomography (AS-OCT). MATERIALS AND METHODS: The study group (n=160 eyes) consisted of clinically diagnosed keratoconus eyes; the control group (n=160) consisted of nonkeratoconic eyes. Three separate, three-dimensional epithelial thickness maps were obtained employing AS-OCT, enabling investigation of the pupil center, average, mid-peripheral, superior, inferior, maximum, minimum, and topographic epithelial thickness variability. Intraindividual repeatability of measurements was assessed. We introduced correlation of the epithelial data via newly defined indices. The epithelial thickness indices were then correlated with two Scheimpflug imaging-derived AS-irregularity indices: the index of height decentration, and the index of surface variance highly sensitive to early and advancing keratoconus diagnosis as validation. RESULTS: Intraindividual repeatability of epithelial thickness measurement in the keratoconic group was on average 1.67 mum. For the control group, repeatability was on average 1.13 mum. In the keratoconic group, pupil-center epithelial thickness was 51.75+/-7.02 mum, while maximum and minimum epithelial thickness were 63.54+/-8.85 mum and 40.73+/-8.51 mum. In the control group, epithelial thickness at the center was 52.54+/-3.23 mum, with maximum 55.33+/-3.27 mum and minimum 48.50+/-3.98 mum epithelial thickness. Topographic variability was 6.07+/-3.55 mum in the keratoconic group, while for the control group it was 1.59+/-0.79 mum. In keratoconus, topographic epithelial thickness change from normal, correlated tightly with the topometric asymmetry indices of IHD and ISV derived from Scheimpflug imaging. CONCLUSION: Simple, OCT-derived epithelial mapping, appears to have critical potential in early and advancing keratoconus diagnosis, confirmed with its correlation with established Scheimpflug-derived asymmetry topometric indices.

PURPOSE/OBJECTIVE:To report novel application of topographically-customized collagen crosslinking aiming to achieve hyperopic refractive changes. Two approaches were evaluated, one based on epithelium-off and one based on epithelium-on (transepithelial). METHODS:A peripheral annular-shaped topographically customizable design was employed for high-fluence ultraviolet (UV)-A irradiation aiming to achieve hyperopic refractive changes. A total of ten eyes were involved in this study. In group-A (five eyes), a customizable ring pattern was employed to debride the epithelium by excimer laser ablation, while in group-B (also five eyes), the epithelium remained intact. In both groups, specially formulated riboflavin solutions were applied. Visual acuity, cornea clarity, keratometry, topography, and pachymetry with a multitude of modalities, as well as endothelial cell counts were evaluated. RESULTS:One year postoperatively, the following changes have been noted: in group-A, average uncorrected distance visual acuity changed from 20/63 to 20/40. A mean hyperopic refractive increase of +0.75 D was achieved. There was some mild reduction in the epithelial thickness. In group-B, average uncorrected distance visual acuity changed from 20/70 to 20/50. A mean hyperopic refractive increase of +0.85 D was achieved. Epithelial thickness returned to slightly reduced levels (compared to baseline) in group-A, whereas to slightly increased levels in group-B. CONCLUSION/CONCLUSIONS:We introduce herein the novel application of a topographically-customizable collagen crosslinking to achieve a hyperopic refractive effect. This novel technique may be applied either with epithelial removal, offering a more stable result or with a non-ablative and non-incisional approach, offering a minimally invasive alternative.

PURPOSE: To investigate, by high-precision digital analysis of data provided by Scheimpflug imaging, changes in pupil size and shape and anterior chamber (AC) parameters following cataract surgery. PATIENTS AND METHODS: The study group (86 eyes, patient age 70.58+/-10.33 years) was subjected to cataract removal surgery with in-the-bag intraocular lens implantation (pseudophakic). A control group of 75 healthy eyes (patient age 51.14+/-16.27 years) was employed for comparison. Scheimpflug imaging (preoperatively and 3 months postoperatively) was employed to investigate central corneal thickness, AC depth, and AC volume. In addition, by digitally analyzing the black-and-white dotted line pupil edge marking in the Scheimpflug "large maps," the horizontal and vertical pupil diameters were individually measured and the pupil eccentricity was calculated. The correlations between AC depth and pupil shape parameters versus patient age, as well as the postoperative AC and pupil size and shape changes, were investigated. RESULTS: Compared to preoperative measurements, AC depth and AC volume of the pseudophakic eyes increased by 0.99+/-0.46 mm (39%; P<0.001) and 43.57+/-24.59 mm(3) (36%; P<0.001), respectively. Pupil size analysis showed that the horizontal pupil diameter was reduced by -0.27+/-0.22 mm (-9.7%; P=0.001) and the vertical pupil diameter was reduced by -0.32+/-0.24 mm (-11%; P<0.001). Pupil eccentricity was reduced by -39.56%; P<0.001. CONCLUSION: Cataract extraction surgery appears to affect pupil size and shape, possibly in correlation to AC depth increase. This novel investigation based on digital analysis of Scheimpflug imaging data suggests that the cataract postoperative photopic pupil is reduced and more circular. These changes appear to be more significant with increasing patient age.

PURPOSE: To evaluate safety, efficacy, ergonomy, and refractive and keratometric stability in high myopia LASIK procedures using a novel femtosecond and excimer laser surgery platform. METHODS: One hundred sixteen eyes in consecutive cases of high myopic LASIK ( >/= -6.00 diopters [D]) with the Alcon-WaveLight FS200 femtosecond and EX500 excimer lasers (Alcon Laboratories, Fort Worth, TX) were evaluated preoperatively and postoperatively for the following parameters: refractive error, corrected distance visual acuity, uncorrected distance visual acuity, spherical equivalent correction, keratometry (with Placido topography and Scheimpflug tomography), and refractive astigmatism. Average follow-up time was 6.2 months (range: 3 to 12 months). RESULTS: Postoperative average refractive error was -0.37, -0.43, and -0.25 D for the 3-, 6-, and 12-month period, compared to -7.67 +/- 1.55 D preoperatively. At 3, 6, and 12 months postoperatively 94%, 96.3%, and 100% of eyes, respectively, were within 1.0 D defocus equivalent. Postoperative refractive astigmatism was -0.21, -0.21, -0.13 D for the 3-, 6-, and 12-month period compared to -1.07 +/- 1.91 D preoperatively. The proportion of eyes with postoperative astigmatism within 0.25 D was 85.3%, 81.5%, and 100%, for the 3-, 6-, and 12-month visit, respectively. Keratometric stability was within 0.22 D after the 12-month visit. There was no epithelial ingrowth or diffuse lamellar keratitis in any case. CONCLUSIONS: Clinical outcomes with this technique and technology appear to be promising in high level uncorrected visual rehabilitation of high myopia. There was small regression potential in the sample evaluated.