Identifying Peripheral Neuropathy in Colour Fundus Photographs Based on Deep Learning.

The aim of this study was to develop and validate a deep learning-based system to detect peripheral neuropathy (DN) from retinal colour images in people with diabetes. Retinal images from 1561 people with diabetes were used to predictDN diagnosed on vibration perception threshold. A total of 189 had diabetic retinopathy (DR), 276 had DN, and 43 had both DR and DN.

Light scattering and wavefront aberrations in in vivo imaging of the rat eye: a comparison study.

Purpose: In vivo imaging of the retina is becoming an increasingly important research method. General anesthesia rapidly compromises the corneal surface, which increases scattering. In addition, wavefront aberrations limit the maximum imaging resolution.

Centroid displacement statistics of the eye aberration.

We discuss a method for the study of the spatial statistics of the ocular aberrations, based on the direct use of the Hartmann-Shack centroid displacements, avoiding the wavefront reconstruction step. Centroid diagrams are introduced as a helpful aid to visualize basic properties of the aberration datasets, and slope-related second-order statistical functions are applied to check the compatibility between the experimental data and different models for the aberration statistics. Preliminary results suggest that no single power-law spectrum (e.

Designing a holographic modal wavefront sensor for the detection of static ocular aberrations.

The extent to which holographic modal wavefront sensing can be applied to the detection of ocular aberrations was investigated. First, the idea of extending the dynamic range of the sensor by increasing the mask bias and the collection area of the pinhole detectors used in the sensor is reviewed. Errors in the detection of single-mode aberrations owing to reduced coherence from retinal scattering, photon, readout, and quantization noise are evaluated.

Translational and rotational pupil tracking by use of wavefront aberration data and image registration techniques.

We present a methodology with which to evaluate translations and rotations of wavefront aberration measurements of systems in which the exit pupil suffers displacements and rotations with respect to the reference frame of the measuring device. We propose to use image registration techniques to account for rotations, translations, and scale changes of the pupil. We present a proof of principle, using an artificial eye in addition to computer simulations.

Sampling geometries for ocular aberrometry: A model for evaluation of performance.

The purpose of this work is to outline a simple model to assess the relative merits of different sampling grids for ocular aberrometry and illustrate it with an example. While in traditional Hartmann-Shack setups the sampling grid geometries have been somewhat restricted by the geometries of the available microlens arrays, other techniques such as laser ray tracing or spatially resolved refractometry allow for a greater freedom of choice. For all available setups, including HS, it is worth studying which of these choices perform better in terms of accuracy (closeness of the obtained results to the actual ones) and precision (uncertainty of the obtained results).

Benefit of higher closed-loop bandwidths in ocular adaptive optics.

We present an ocular adaptive optics system with a wavefront sampling rate of 240 Hz and maximum recorded closed-loop bandwidth close to 25 Hz, but with typical performances around 10 Hz. The measured bandwidth depended on the specific system configuration and the particular subject tested. An analysis of the system performance as a function of achieved bandwidth showed consistently higher Strehl ratios for higher closed-loop bandwidths.

Repeatability of ocular wavefront measurement.

Purpose: To assess the repeatability of measurements of ocular aberrations using wavefront sensing in a small group of observers and to assess the potential effect of measurement error on custom corneal correction due to this variability.

Method: A Shack-Hartmann wavefront sensor was used to measure the ocular wavefront in nine eyes. Head position was stabilized using a dental bite bar, and the pupil was centred using a cathode ray tube monitor and circular grating.

Aberrations of the human eye in visible and near infrared illumination.

Purpose: In most current aberrometers, near infrared light is used to measure ocular aberrations, whereas in some applications, optical aberration data in the visible range are required. We compared optical aberration measurements using infrared (787 nm) and visible light (543 nm) in a heterogeneous group of subjects to assess whether aberrations are similar in both wavelengths and to estimate experimentally the ocular chromatic focus shift.

Methods: Ocular aberrations were measured in near infrared and visible light using two different laboratory-developed systems: laser ray tracing (LRT) and Shack-Hartmann.

Ocular aberrations with ray tracing and Shack-Hartmann wave-front sensors: does polarization play a role?

Ocular aberrations were measured in 71 eyes by using two reflectometric aberrometers, employing laser ray tracing (LRT) (60 eyes) and a Shack-Hartmann wave-front sensor (S-H) (11 eyes). In both techniques a point source is imaged on the retina (through different pupil positions in the LRT or a single position in the S-H). The aberrations are estimated by measuring the deviations of the retinal spot from the reference as the pupil is sampled (in LRT) or the deviations of a wave front as it emerges from the eye by means of a lenslet array (in the S-H).