Anterior-Segment Swept-Source Ocular Coherence Tomography and Scheimpflug Imaging Agreement for Keratometry and Pupil Measurements in Healthy Eyes

This study examines agreement between the devices Anterion® and Pentacam HR® used for corneal and pupil measurements in healthy eyes. The parameters compared between the two devices were: anterior Km (D), anterior K2 (D), anterior K1 (D), anterior K1 axis (°), anterior astigmatism (D), anterior K max (D), posterior Km (D), posterior K2 (D), posterior K1 (D), posterior K1 axis (°), posterior astigmatism (D), CCT (µm), thinnest point thickness (µm), thinnest point X-coordinate (mm), thinnest point Y-coordinate (mm), pupil diameter (mm), pupil center-corneal vertex distance (mm) (angle kappa), pupil centroid angle (°), pupil centroid X-coordinate (mm), and pupil centroid Y-coordinate (mm). The Student’s t test for independent samples identified significant differences (p < 0.005) between devices for the measurements anterior and posterior flat K axis, posterior flat K, steep K, and mean K. For these last three measurements, although significant, none of the differences were clinically relevant. Corneal power and thickness measurements except Kf axis showed excellent agreement between Anterion and Pentacam. In a clinical setting we would not recommend the interchangeable use of Pentacam and Anterion for measurement of pupil parameters.

Distribution of preoperative angle alpha and angle kappa values in patients undergoing multifocal refractive lens surgery based on a positive contact lens test

Purpose To assess the preoperative objective angle alpha and angle kappa measurements of patients deciding to undergo multifocal refractive lens surgery based on a subjective positive multifocal contact lens test (MCLT). Methods Retrospective, consecutive case series. Alpha and kappa angles were measured using the iTrace aberrometer. All patients also performed a 1-week MCLT. Only patients with a positive MCLT underwent surgery. Visual outcome (UCVA) was obtained in the 1-year follow-up. We assessed the preoperative distribution of angle values within MCLT positive and negative patient groups. Results Two hundred seventeen eyes (111 patients) were included. Mean age was 56.4 years (SD 5.6) and 46.9% were female. In 71 eyes (38 patients), MCLT was positive. Of them, 12 eyes (17%) had an angle alpha and angle kappa ≥ 0.5mm. Of 146 eyes (73 patients) who refrained from surgery due to a negative MCLT, 71 eyes (48.6%) had both angles small (<0.5mm). In the 1-year follow-up, UCVA improved by 0.68 logMAR (SD 0.51; p<0.001) from baseline. Eyes with both small angle alpha and kappa sizes improved by 0.78 logMAR (SD 0.56), as did eyes with high (≥0.5mm) angle sizes (0.82 logMAR (SD 0.53). UCVA of eyes (n=24) with high alpha but low kappa sizes improved less (−0.31 logMAR (SD 0.13; p=0.019)). Conclusion Four out of five patients with a positive MCLT also had correspondingly small angle values. One-half of patients with low preoperative angle values refrained from surgery due to a negative MCLT result. One-year visual acuity improvement was substantial and independent from angle sizes.

Elongation of the disc-fovea distance and retinal vessel straightening in high myopia in a 10-year follow-up of the Beijing eye study

To assess changes in the disc-fovea distance (DFD) in highly myopic eyes in a 10-year population-based follow-up study. The case control study included all highly myopic eyes (myopic refractive error ≥ − 6.0 diopters or axial length ≥ 26.0 mm) and a randomized group of non-highly myopic eyes examined in the population-based Beijing Eye Study 2001 and 2011. Using fundus photographs and optical coherence tomographic images, we assessed changes in DFD, parapapillary gamma zone, angle kappa (angle between the temporal arterial arcades), and course of papillo-macular retinal vessels. The study included 89 highly myopic eyes and 86 non-highly myopic eyes. DFD elongation, gamma zone widening, angle kappa decrease and straightening of papillo-macular retinal vessels were detected more often (all P < 0.001) in the highly myopic group than in the non-highly myopic group (63/89 versus 9/86;75/89 versus 18/86;61/89 versus 9/86; and 58/89 versus 7/86,respectively). Gamma zone enlargement, angle kappa reduction and papillo-macular retinal vessel straightening were significantly (all P < 0.001) associated with DFD elongation. The length of macular Bruch’s membrane on the disc-fovea line and the vertical distance between the temporal arterial arcade did not change during follow-up. DFD elongation (10-year incidence 70.8% in highly myopic eyes) was associated with gamma zone enlargement, while macular Bruch’s membrane length remained unchanged. It supports the notion of a temporal shift of an otherwise stable posterior Bruch’s membrane in axially elongated eyes. Straightening of the papillo-macular vessels with increasing gamma zone width suggests a coincident stretching of the papillo-macular retinal nerve fibers and inner limiting membrane.

The Distribution of IOL Center and Its Relationship with Internal Ocular Objective Visual Quality in Cataract Patients

Background: To investigate the distribution of the center of the intraocular lens (IOL) after phacoemulsification, and to assess the correlation between the center of IOL and preoperative angle kappa, angle alpha, and objective internal visual quality, respectively, in cataract patients with monofocal and bifocal IOLs implantation. Methods: Prospective cross-section cases series. One hundred and thirty-seven eyes of 107 patients who underwent phacoemulsification were included. Preoperative angle kappa and alpha, postoperative internal ocular aberrations, internal objective visual quality, and the center of IOL relative to the visual axis (CIV) was evaluated using iTrace system. Independent sample t-tests and Pearson correlations were performed.Results: Locations of CIV were scattered in all directions centered on corneal light reflection for both C-Loop designed IOL and plate-haptic designed IOL. No correlations were found between CIV and preoperative angle kappa and alpha in both magnitude and orientation. No correlations were found between CIV and postoperative internal ocular aberrations (astigmatism, coma, and trefoil). In the bifocal IOLs group, the CIV was negatively correlated to the internal Strehl ratio at 3mm; however, it was not correlated to the Strehl ratio at 5mm. The magnitude of CIV was positively correlated to the length of the optic axis.Conclusions: CIV was not predictable according to angle kappa and alpha before cataract surgery. CIV was not related to internal ocular aberration, but large CIV may lead to light scattering due to steps between diffractive rings in patients with small pupil sizes. The magnitude of CIV may be greater in cataract patients with longer optic axis.Trial registration: retrospectively registered.