PURPOSE. To assess the suitability of corneal anterior and posterior surface aberrations and thickness profile data for discrimination between eyes with early keratoconus (KC), fellow eyes of eyes ...with early KC, and normal eyes. METHODS. Thirty-two eyes (group 1) of 25 patients were newly diagnosed with KC; 17 eyes of 17 patients (group 2) were asymptomatic fellow eyes without clinical signs of KC. One hundred twenty-three healthy eyes of 69 patients were negative control eyes (group 3). Zernike coefficients from anterior and posterior surfaces, data from corneal thickness spatial profiles, and output values of discriminant functions based on wavefront and pachymetry data were assessed by receiver operating characteristic (ROC) curve analysis for their usefulness in discriminating between KC (groups 1, 2) eyes and control eyes. RESULTS. Vertical coma (C(3)(-1)) from the anterior surface was the coefficient with the highest ability to discriminate between groups 2 and 3 (area under the ROC curve A(z)ROC = 0.980; cutoff, -0.2 microm). For posterior wavefront coefficients and pachymetry data, A(z)ROC values were lower. Constructing discriminant functions from Zernike coefficients increased A(z)ROC values. The function containing first-surface data reached an A(z)ROC of 0.993; the functions containing posterior surface or pachymetry data had lower A(z)ROC values (0.932 and 0.903, respectively). The function with anterior, posterior, and pachymetry data reached an A(z)ROC of 1.0. CONCLUSIONS. Corneal wavefront and pachymetry data enabled highly accurate distinction of eyes with subclinical keratoconus from normal eyes. Posterior aberrations and thickness spatial profile data did not markedly improve discriminative ability over that of anterior wavefront data alone.
To analyze the repeatability of corneal astigmatism measurements with 2 autokeratometers (IOLMaster 500 and Lenstar LS 900), 2 Placido topographers (Keratron Scout and Atlas 9000), and a Scheimpflug ...tomographer (Pentacam HR).
Department of Ophthalmology, Goethe University, Frankfurt, Germany.
Prospective case series.
The inclusion criteria were a minimum age of 18 years, corneal astigmatism of 3.00 diopters or less, and patient's consent to participate in the study. The main exclusion criteria were corneal pathologies, trauma, previous surgery, hard contact lens wear in the previous 3 months, and soft contact lens wear in the previous 6 weeks. In addition to manifest refraction and visual acuity measurements, all subjects had 2 full measurements of 1 eye using each device. Anterior corneal astigmatism and total corneal refractive power via calculations derived from the Scheimpflug tomographer were evaluated. Statistical analysis was performed using the Bland-Altman method and multiple linear regression analysis.
Forty-five eyes of 45 subjects (mean age 53.11 years ± 10.43 SD; 23 left eyes; 33 women) were included. The mean intermeasurement differences were approximately zero for all devices. The relative coefficient of repeatability of anterior corneal astigmatism, steep axis, and the vector analysis parameter J180 were lowest with the Scheimpflug tomographer. Total corneal refractive power measured with the Scheimpflug tomographer showed the highest repeatability in the larger diameter zones.
The Scheimpflug tomographer yielded higher repeatability of corneal astigmatism measurements, with total corneal refractive power measurements being as repeatable as established metrics.
Dr. Kohnen receives research support from Abbott Medical Optics Inc., Alcon Pharma GmbH, Bausch & Lomb GmbH, Carl Zeiss Meditec Vertriebsgesellschaft mbH, Hoya Surgical Optics GmbH, Oculus Optikgeräte GmbH, and Schwind eye-tech-solutions GmbH and Co. KG. He receives travel reimbursement, lecture fees and is a consultant to Abbott Medical Optics Inc., Alcon Pharma GmbH, Carl Zeiss Meditec Vertriebsgesellschaft mbH, Geuder AG, Oculus Optikgeräte GmbH, Schwind eye-tech-solutions GmbH and Co. KG, TearLab Corp., Thieme Compliance, and Ziemer Ophthalmic Systems AG. None of the other authors has a financial or proprietary interest in any of the materials or methods mentioned.
Purpose To describe corneal higher-order wavefront aberrations of clinically inconspicuous fellow eyes in patients with early keratoconus (KC). Design Prospective comparative case series, conducted ...at a university eye hospital outpatient clinic. Methods Twenty-three eyes (group 1) were newly diagnosed with KC; 10 eyes (group 2) were asymptomatic fellow eyes that showed neither major topographic anomaly nor clinical signs of KC; 127 healthy eyes of 74 patients served as negative controls (group 3). A seventh-order Zernike decomposition of first-surface aberrations was performed. Single Zernike coefficients, higher-order aberration root mean square (HOA RMS) values, the Z3 index and the output values of discriminant analysis D13 (with input from groups 1 and 3) and D23 (groups 2 and 3) were assessed for their usefulness to discriminate between clinically normal fellow eyes, KC eyes and controls by plotting receiver-operating characteristic (ROC) curves. Results There were significant differences between group 1 and group 3 for 11 Zernike coefficients, Z3, total HOA RMS, coma RMS and third-order RMS. Group 2 and 3 showed significant differences only for the coefficients Z3−1 and Z5−1 . Z3−1 , D13 , and D23 discriminated between groups 1 and 3 with maximum sensitivity and specificity. For discrimination between groups 2 and 3, D23 turned out to be the best parameter (Az ROC = 0.98), followed by Z3−1 (Az ROC = 0.96). Conclusions Clinically normal fellow eyes of eyes with early KC showed significant differences of first-surface aberrations compared to normal eyes and could therefore be considered as eyes with subclinical KC.
To determine the impact of spherical and aspheric foldable intraocular lens (IOL) tilt and decentration on optical quality after cataract surgery in an intraindividual comparative study.
Department ...of Ophthalmology, Goethe-University, Frankfurt am Main, Germany.
Randomized implantation of a spherical IOL (Sensar AR40e) was performed in 1 eye and of an aspheric IOL with negative spherical aberration (Tecnis Z9000) in the contralateral eye. Three to 4 months postoperatively, the wavefront was measured and higher-order aberrations (HOAs) were calculated for virtual pupil diameters of 3.5 mm and 6.0 mm. Tilt and decentration of the IOLs were measured using Scheimpflug photography. The tilt and decentration, HOAs, and best corrected visual Strehl ratio of the optical transfer function (BCVSOTF) calculated from the wavefront aberration were compared. The effect of tilt and decentration on HOAs and optical quality was assessed using multiple regression analysis.
The mean optic tilt was 2.89 degrees +/- 1.46 (SD) for the spherical IOL and 2.85 +/- 1.36 degrees for the aspheric IOL. The mean optic decentration was 0.19 +/- 0.12 mm and 0.27 +/- 0.16 mm, respectively. No significant intergroup differences in IOL tilt or decentration were found. Tilt and decentration did not significantly affect the BCVSOTF with either IOL.
The amounts of tilt and decentration of both IOLs were not large enough to cause deterioration of optical quality. Thus, when IOL tilt and decentration are within normal limits, they do not compromise the correction of spherical aberration by the aspheric IOL.
To evaluate the repeatability of different lens densitometry analysis modes performed with Scheimpflug imaging using the Pentacam HR device.
University eye hospital, Frankfurt am Main, Germany.
...Cross-sectional study.
Eyes were analyzed under mydriasis during 2 examinations performed by the same examiner. Three single measurements were taken to assess lens densitometry via 3 modes as follows: peak (maximum), linear (vertical axis), and 3-dimensional (3-D). Measurements were also taken using 3 cylindrical reference blocks (P) with different diameters (2.0 mm, 4.0 mm, 6.00 mm) composing the whole lens depth. Repeatability was tested using Bland-Altman analysis. As statistical parameters, the coefficient of repeatability (CoR) and the relative repeatability (RR) were applied.
The study analyzed 105 eyes. The CoR of the peak modus was 5.6 (RR, 29.8%); of the linear modus, 0.9 (RR, 8.8%); and of the 3-D modus, 0.36 (RR, 3.6%). The values of the P mode were lower, with a CoR between 0.19 and 0.30 (RR, 2.1%-3.3%).
Lens densitometry using Scheimpflug imaging was highly repeatable. However, repeatability was dependent on the analysis mode used. Repeatability decreased with increasing opacification.
To validate the discriminative ability of wavefront- and pachymetry-based corneal topographic metrics to detect subclinical keratoconus in a new patient collective.
Department of Ophthalmology, ...Goethe-University, Frankfurt am Main, Germany.
Retrospective cross-sectional study.
Normal fellow eyes with early keratoconus and preoperative eyes with an uneventful follow-up without signs of iatrogenic keratectasia 12 months after laser in situ keratoconus were included. Zernike coefficients from the anterior and posterior surfaces and corneal thickness spatial profiles and corresponding discriminant functions were assessed for their usefulness to discriminate between eyes with subclinical keratoconus and normal eyes using receiver-operating-characteristic (ROC) curve analysis. Discriminant functions were obtained from a previous study and constructed de novo from the present collective.
The anterior C(1,-1) and C(3,-1) coefficients had the highest area under the ROC curve (both 0.87). The anterior 5th-order root mean square (RMS) was the RMS value with the maximum area under the ROC curve (0.90). The discriminant function with input from anterior and posterior Zernike coefficients (DAP) and DAP including pachymetry data (DAPT) performed best (area under ROC curve 0.864 and 0.857, respectively). Applying cutoff values from a previous study resulted in a minimal drop in accuracy (0.0% to 1.3%). The construction of discriminant functions from the present dataset resulted in a gain in accuracy of between 3.5% and 9.6%, with DAPT reaching the maximum area under the ROC curve of 0.956.
Validation in a new and larger patient collective proved the usefulness of metrics based on corneal wavefront and pachymetry for the detection of subclinical keratoconus.
No author has a financial or proprietary interest in any material or method mentioned.
To present the Tomographic and Biomechanical Index (TBI), which combines Scheimpflugbased corneal tomography and biomechanics for enhancing ectasia detection.
Patients from different continents were ...retrospectively studied. The normal group included 1 eye randomly selected from 480 patients with normal corneas and the keratoconus group included 1 eye randomly selected from 204 patients with keratoconus. There were two groups: 72 ectatic eyes with no surgery from 94 patients with very asymmetric ectasia (VAE-E group) and the fellow eyes of these patients with normal topography (VAE-NT group). Pentacam HR and Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) parameters were analyzed and combined using different artificial intelligence methods. The accuracies for detecting ectasia of the Belin/Ambrósio Deviation (BAD-D) and Corvis Biomechanical Index (CBI) were compared to the TBI, considering the areas under receiver operating characteristic curves (AUROCs).
The random forest method with leave-one-out cross-validation (RF/LOOCV) provided the best artificial intelligence model. The AUROC for detecting ectasia (keratoconus, VAE-E, and VAE-NT groups) of the TBI was 0.996, which was statistically higher (DeLong et al., P < .001) than the BAD-D (0.956) and CBI (0.936). The TBI cut-off value of 0.79 provided 100% sensitivity for detecting clinical ectasia (keratoconus and VAE-E groups) with 100% specificity. The AUROCs for the TBI, BAD-D, and CBI were 0.985, 0.839, and 0.822 in the VAE-NT group (DeLong et al., P < .001). An optimized TBI cut-off value of 0.29 provided 90.4% sensitivity with 96% specificity in the VAE-NT group.
The TBI generated by the RF/LOOCV provided greater accuracy for detecting ectasia than other techniques. The TBI was sensitive for detecting subclinical (fruste) ectasia among eyes with normal topography in very asymmetric patients. The TBI may also confirm unilateral ectasia, potentially characterizing the inherent ectasia susceptibility of the cornea, which should be the subject of future studies. J Refract Surg. 2017;33(7):434-443..
To study the distribution of refractive errors among adults of European descent.
Population-based eye study in Germany with 15010 participants aged 35-74 years.
The study participants underwent a ...detailed ophthalmic examination according to a standardised protocol. Refractive error was determined by an automatic refraction device (Humphrey HARK 599) without cycloplegia. Definitions for the analysis were myopia <-0.5 dioptres (D), hyperopia >+0.5 D, astigmatism >0.5 cylinder D and anisometropia >1.0 D difference in the spherical equivalent between the eyes. Exclusion criterion was previous cataract or refractive surgery.
13959 subjects were eligible. Refractive errors ranged from -21.5 to +13.88 D. Myopia was present in 35.1% of this study sample, hyperopia in 31.8%, astigmatism in 32.3% and anisometropia in 13.5%. The prevalence of myopia decreased, while the prevalence of hyperopia, astigmatism and anisometropia increased with age. 3.5% of the study sample had no refractive correction for their ametropia.
Refractive errors affect the majority of the population. The Gutenberg Health Study sample contains more myopes than other study cohorts in adult populations. Our findings do not support the hypothesis of a generally lower prevalence of myopia among adults in Europe as compared with East Asia.
Corneal scarring remains a major cause of blindness world-wide, with limited treatment options, all of which have side-effects. Here, we tested the hypothesis that topical application of ...Rosiglitazone, a Thiazolidinedione and ligand of peroxisome proliferator activated receptor gamma (PPARγ), can effectively block scar formation in a cat model of corneal damage. Adult cats underwent bilateral epithelial debridement followed by excimer laser ablation of the central corneal stroma to a depth of ~160 µm as a means of experimentally inducing a reproducible wound. Eyes were then left untreated, or received 50 µl of either 10 µM Rosiglitazone in DMSO/Celluvisc, DMSO/Celluvisc vehicle or Celluvisc vehicle twice daily for 2 weeks. Cellular aspects of corneal wound healing were evaluated with in vivo confocal imaging and post-mortem immunohistochemistry for alpha smooth muscle actin (αSMA). Impacts of the wound and treatments on optical quality were assessed using wavefront sensing and optical coherence tomography at 2, 4, 8 and 12 weeks post-operatively. In parallel, cat corneal fibroblasts were cultured to assess the effects of Rosiglitazone on TGFβ-induced αSMA expression. Topical application of Rosiglitazone to cat eyes after injury decreased αSMA expression and haze, as well as the induction of lower-order and residual, higher-order wavefront aberrations compared to vehicle-treated eyes. Rosiglitazone also inhibited TGFβ-induced αSMA expression in cultured corneal fibroblasts. In conclusion, Rosiglitazone effectively controlled corneal fibrosis in vivo and in vitro, while restoring corneal thickness and optics. Its topical application may represent an effective, new avenue for the prevention of corneal scarring with distinct advantages for pathologically thin corneas.
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