Characterization of Corneoscleral Geometry Using Fourier Transform Profilometry in the Healthy Eye.

OBJECTIVE: To characterize peculiarities of the corneoscleral geometry in healthy eyes. METHODS: This is a prospective case series including 88 healthy eyes of 88 patients with an age ranging from 21 to 73 years. A complete ocular examination was performed with emphasis on the analysis of the corneoscleral topographic profile with the Fourier transform profilometer Eye Surface Profiler (Eaglet-Eye BV, Houten, the Netherlands). The distribution of different topographic parameters was evaluated, as well as the correlations between corneal and scleroconjunctival parameters. RESULTS: Mean values of 8.64±0.37 (range, 7.81-9.50 mm), 6.06±0.52 (4.88-7.63 mm) and 11.93±1.32 mm (8.17-15.89 mm) were obtained for inner, limbal, and outer best-fit sphere, respectively. Mean values of 8.54±0.38 (7.86-9.66 mm) and 13.35±1.29 mm (11.05-17.31 mm) were obtained for mean corneal and scleral radius, respectively. Regarding tangent angles at limbus, mean values of 35.31±6.55°, 38.76±5.90°, 32.75±7.04°, and 25.91±8.99° were obtained for nasal, temporal, superior, and inferior angles, respectively. Mean difference between temporal and nasal sagittal heights increased from -1.48±120.70 µm for a chord of 11 mm to 73.53±236.55 µm for a chord of 14 mm. A weak but statistically significant correlation was found between corneal and scleral radii (r=0.325, P=0.004). The maximum sagittal height for a diameter of 12 mm was significantly correlated with flattest keratometry, astigmatism, corneal diameter, and corneal eccentricity (R: 0.77, P<0.001). CONCLUSIONS: The scleroconjunctival surface in the healthy eye presents some level of nasotemporal asymmetry that is higher with increasing diameters of analysis.

Intra-session repeatability of iridocorneal angle measurements provided by a Scheimpflug photography-based system in healthy eyes.

PURPOSE: The purpose of this study was to evaluate intra-session repeatability of measurements of the iridocorneal angle at different meridians in the nasal and temporal areas in healthy eyes using the Sirius Scheimpflug photography-based system in glaucoma analysis mode. METHODS: A total of 43 eyes of 43 patients ranging in age from 36 to 79 years were enrolled in the study. All eyes received a comprehensive ophthalmologic examination including a complete anterior segment analysis with the Costruzione Strumenti Oftalmici [CSO] Sirius system. Three consecutive measurements of nasal and temporal angles at 0°, ±10°, ±20°, and ±30° meridians were obtained in order to assess the intra-session repeatability of iridocorneal angle measurements provided by the device using the glaucoma analysis mode. Within-subject standard deviation (Sw), coefficient of variation (CV), and intraclass correlation coefficient (ICC) values were calculated. RESULTS: The mean Sw was 1.07 ± 1.09°, 1.22 ± 1.53°, 0.66 ± 0.51°, 0.86 ± 0.57°, 0.68 ± 0.65°, 0.84 ± 0.68°, and 0.91 ± 0.70° at the temporal 30°, 20°, 10°, 0°, -10°, -20°, and -30° positions, respectively. Mean Sw was 3.13 ± 3.15°, 3.43 ± 3.63°, 2.75 ± 2.29°, 2.19 ± 1.55°, 1.90 ± 1.49°, 2.14 ± 1.74°, and 2.24 ± 2.06° at the temporal -30°, -20°, -10°, 0°, 10°, 20°, and 30° positions, respectively. Mean CV ranged from 1.36 ± 1.05 % (nasal 0° position) to 10.92 ± 13.95 % (nasal -20° position). ICC values ranged from 0.778 to 0.972. CONCLUSIONS: The glaucoma analysis mode of the Sirius system provides consistent measurements of the iridocorneal angle at different meridians in healthy eyes, with slightly less consistency for nasal measurements. It may be considered a clinically useful non-invasive technique for the detection of potentially occludable angles.

Clinical utility of ocular residual astigmatism and topographic disparity vector indexes in subclinical and clinical keratoconus.

PURPOSE: We aimed to characterize the distribution of the vector parameters ocular residual astigmatism (ORA) and topography disparity (TD) in a sample of clinical and subclinical keratoconus eyes, and to evaluate their diagnostic value to discriminate between these conditions and healthy corneas. METHODS: This study comprised a total of 43 keratoconic eyes (27 patients, 17-73 years) (keratoconus group), 11 subclinical keratoconus eyes (eight patients, 11-54 years) (subclinical keratoconus group) and 101 healthy eyes (101 patients, 15-64 years) (control group). In all cases, a complete corneal analysis was performed using a Scheimpflug photography-based topography system. Anterior corneal topographic data was imported from it to the iASSORT software (ASSORT Pty. Ltd), which allowed the calculation of ORA and TD. RESULTS: Mean magnitude of the ORA was 3.23 ± 2.38, 1.16 ± 0.50 and 0.79 ± 0.43 D in the keratoconus, subclinical keratoconus and control groups, respectively (p < 0.001). Mean magnitude of the TD was 9.04 ± 8.08, 2.69 ± 2.42 and 0.89 ± 0.50 D in the keratoconus, subclinical keratoconus and control groups, respectively (p < 0.001). Good diagnostic performance of ORA (cutoff point: 1.21 D, sensitivity 83.7 %, specificity 87.1 %) and TD (cutoff point: 1.64 D, sensitivity 93.3 %, specificity 92.1 %) was found for the detection of keratoconus. The diagnostic ability of these parameters for the detection of subclinical keratoconus was more limited (ORA: cutoff 1.17 D, sensitivity 60.0 %, specificity 84.2 %; TD: cutoff 1.29 D, sensitivity 80.0 %, specificity 80.2 %). CONCLUSION: The vector parameters ORA and TD are able to discriminate with good levels of precision between keratoconus and healthy corneas. For the detection of subclinical keratoconus, only TD seems to be valid.

Characterization of Dysfunctional Lens Index and Opacity Grade in a Healthy Population.

This study enrolled 61 volunteers (102 eyes) classified into subjects < 50 years (group 1) and subjects ≥ 50 years (group 2). Dysfunctional Lens Index (DLI); opacity grade; pupil diameter; and corneal, internal, and ocular higher order aberrations (HOAs) were measured with the i-Trace system (Tracey Technologies). Mean DLI was 8.89 ± 2.00 and 6.71 ± 2.97 in groups 1 and 2, respectively, being significantly higher in group 1 in all and right eyes (both p < 0.001). DLI correlated significantly with age (Rho = −0.41, p < 0.001) and pupil diameter (Rho = 0.20, p = 0.043) for all eyes, and numerous internal and ocular root-mean square HOAs for right, left, and all eyes (Rho ≤ −0.25, p ≤ 0.001). Mean opacity grade was 1.21 ± 0.63 and 1.48 ± 1.15 in groups 1 and 2, respectively, with no significant differences between groups (p ≥ 0.29). Opacity grade significantly correlated with pupil diameter for right and all eyes (Rho ≤ 0.33, p ≤ 0.013), and with some ocular root-mean square HOAs for right and all eyes (Rho ≥ 0.23, p ≤ 0.020). DLI correlates with age and might be used complementary to other diagnostic measurements for assessing the dysfunctional lens syndrome. Both DLI and opacity grade maintain a relationship with pupil diameter and internal and ocular HOAs, supporting that the algorithms used by the device may be based, in part, on these parameters.

Efficacy of Perceptual Learning-Based Vision Training as an Adjuvant to Occlusion Therapy in the Management of Amblyopia: A Pilot Study.

A retrospective study was conducted to evaluate preliminarily the efficacy of perceptual learning (PL) visual training in medium-term follow-up with a specific software (Amblyopia iNET, Home Therapy Systems Inc., Gold Canyon, AZ, USA) for visual acuity (VA) and contrast sensitivity (CS) recovering in a sample of 14 moderate to severe amblyopic subjects with a previously unsuccessful outcome or failure with patching (PL Group). This efficacy was compared with that achieved in a patching control group (13 subjects, Patching 2). At one-month follow-up, a significant VA improvement in the amblyopic eye (AE) was observed in both groups, with no significant differences between them. Additionally, CS was measured in PL Group and exhibited a significant improvement in the AE one month after the beginning of treatment for 3, 6, 12, and 18 cycles/º (p = 0.003). Both groups showed long-lasting retention of visual improvements. A combined therapy of PL-based visual training and patching seems to be effective for improving VA in children with amblyopia who did not recover vision with patching alone or had a poor patching compliance. This preliminary outcome should be confirmed in future clinical trials.

Interchangeability of corneal curvature and asphericity measurements provided by three different devices.

AIM: To evaluate the interchangeability of keratometric and asphericity measurements provided by three measurement systems based on different optical principles. METHODS: A total of 40 eyes of 40 patients with a mean age of 34.1y were included. In all cases, a corneal curvature analysis was performed with IOL-Master (IOLM), iDesign 2 (ID2), and Sirius systems (SIR). Differences between instruments for flattest (K1) and steepest (K2) keratometric readings, as well as for magnitude and axis of corneal astigmatism were analyzed. Likewise, differences in asphericity (Q) between SIR and ID2 were also evaluated. RESULTS: Mean differences between devices for K1 were 0.20±0.21 (P<0.001), -0.12±0.36 (P=0.046) and -0.32±0.36 D (P<0.001) for the comparisons IOLM-SIR, IOLM-ID2 and SIR-ID2, respectively. The ranges of agreement for these comparisons between instruments were 0.41, 0.70, and 0.70 D. For K2, mean differences were 0.31±0.33 (P<0.001), -0.08±0.43 (P=0.265) and -0.39±0.38 D (P<0.001), with ranges of agreement of 0.65, 0.84, and 0.74 D. Concerning magnitude of astigmatism, ranges of agreement were in the limit of clinical relevance (0.49 D, P=0.011; 0.55 D, P=0.386; 0.43 D, P=0.05). In contrast, ranges of agreement were clinically relevant for astigmatic axis (26.68°, 33.83° and 18.37°, P≥0.121) and for Q between SIR and ID2 (0.16, P<0.001). CONCLUSION: The keratometric corneal power, astigmatic axis and asphericity measurements provide by the three systems evaluated cannot be considered as interchangeable, whereas measurements of corneal astigmatism obtained with SIR and ID2 can be considered as interchangeable for clinical purposes.

Analysis of Intrasession Repeatability of Ocular Aberrometric Measurements and Validation of Keratometry Provided by a New Integrated System in Mild to Moderate Keratoconus.

PURPOSE: To evaluate the intrasession repeatability and validity of corneal curvature measurements provided by a new multifunctional device and to assess the intrasession repeatability of its ocular aberrometric measures. METHODS: This prospective study comprises 37 mild to moderate keratoconus eyes of 37 patients. In all cases, 3 repeated measures of corneal topography and ocular aberrometry were performed with the iDesign 2 system (iD2; Johnson & Johnson Vision Care Inc, Jacksonville, FL) and one keratometric measurement was performed with the intraocular lens-(IOL) Master 500 (Carl Zeiss Meditec Inc, Dublin, CA) and Sirius (CSO) (SIR) systems. RESULTS: The within-subject SD (Sw) was <0.50 D for all iD2 keratometric measurements, with intraclass correlation coefficient (ICC) >0.980. Sw and ICC for the keratometric axis were 2.60 degrees and 0.992, respectively. Concerning aberrations, all Sw values for high-order Zernike terms were ≤0.11 µm (ICC > 0.900), and all Sw values for refraction data were <0.75 D (ICC > 0.95), except for J45. No statistically significant differences were found between the devices in any keratometric parameter evaluated (P ≥ 0.222), but the limits of agreement between the devices were clinically relevant. The magnitude of K readings and astigmatism correlated significantly with the difference in these parameters between iD2 and SIR (0.432 ≤ r ≤ 0.489, P ≤ 0.041). CONCLUSIONS: The iD2 system provides consistent measures of keratometry and ocular aberrometry in eyes with mild to moderate keratoconus. Keratometric data obtained with this system in these eyes cannot be considered as interchangeable with data provided by intraocular lens-Master 500 and SIR.

Differences in corneo-scleral topographic profile between healthy and keratoconus corneas.

PURPOSE: To evaluate the differences in corneo-scleral topographic profile between healthy and keratoconus eyes, and their potential diagnostic ability for keratoconus detection. METHODS: Prospective comparative study including 21 keratoconic eyes (11 patients) and 88 healthy eyes (88 patients). In all cases, a complete eye exam was performed including an evaluation of the corneo-scleral profile. The diagnostic ability of corneo-scleral topographic parameters to detect keratoconus was evaluated using the receiver operating characteristic (ROC) curve. RESULTS: A significant lower inferior tangent angle at limbus (ITA) was found in the keratoconic group compared to the control group (p = 0.024). Regarding sagittal heights, significant differences between groups were found in temporal sagittal height (TSH) for 11 mm (p = 0.040), 12 mm (p = 0.041) and 13 mm corneal chords (p = 0.040), difference between temporal and nasal sagittal heights (T-NSH) for 12 mm (p = 0.025) and 13 mm (p = 0.034), and maximum sagittal height (MaxSH) for 12 mm (p = 0.043), with higher values in keratoconus. In bilateral cases, these differences were not found when comparing with the least severe keratoconus eye. Statistical significance for the ROC curve was only found for ITA (p = 0.025), 12-mm (p = 0.048) and 13-mm TSH (p = 0.042), and 13-mm T-NSH (p = 0.037), with cutoff values associated to limited values of sensitivity and specificity. CONCLUSIONS: The corneo-scleral profile in keratoconus presents higher levels of asymmetry compared to healthy eyes, especially in eyes with moderate and advanced stages of the disease. The diagnostic accuracy of corneo-scleral topographic data alone for keratoconus detection is limited and must be used in conjunction with other clinical parameters.

Clinical outcomes at one year following keratoconus treatment with accelerated transepithelial cross-linking.

This study evaluated the clinical outcomes in keratoconus corneas following accelerated transepithelial corneal collagen cross-linking (CXL) (Avedro KXL® system, Waltham, MA, USA) over one year of follow-up. The mean depth of the demarcation line measured by optical coherence tomography (OCT) was 205.19 µm. One month after surgery, a non-statistically significant change was noted in sphere (P=0.18) and in spherical equivalent (P=0.17), whereas a significant improvement was observed in corrected distance visual acuity (P=0.04). A significant change was observed in topographic astigmatism (P=0.03) and posterior corneal a sphericity (P=0.04). Accelerated transepithelial CXL may be a useful technique for the management of progressive keratoconus.