An integrated software solution for multi-modal mapping of morphological and functional ocular data

Functional Relevance and Structural Correlates of Near Infrared and Short Wavelength Fundus Autofluorescence Imaging in ABCA4-Related Retinopathy

Purpose

To evaluate the functional relevance and structural correlates of autofluorescence (AF) alterations under short-wavelength (SW) and near-infrared (NIR) excitation light in ABCA4-related retinopathy.

Methods

In this prospective, cross-sectional case series, 88 eyes of 44 patients with ABCA4-related retinopathy (mean age, 37.6 years; range, 9-77 years) underwent SW-AF and NIR-AF imaging. The AF images were graded for disease characteristic patterns by two independent readers and correlated with alterations in optical coherence tomography (OCT) and impairment of retinal sensitivity along a foveo-papillary line assessed by fundus-controlled microperimetry.

Results

A centrifugal sequence of AF patterns from atrophic lesions to homogeneous background was found for both AF modalities. The eccentricity of each AF pattern in NIR-AF was larger compared to those in SW-AF (P < 0.001). Increasing eccentricity of each pattern correlated with increasing retinal sensitivity. The distant border of the zone of hyperfluorescent flecks in SW-AF and hypoautofluorescent flecks in NIR-AF correlated with the margins of the ellipsoid zone loss in OCT (r = 0.979 and r = 0.971, P < 0.001). The expansion of hypofluorescent flecks in SW-AF was associated with the boundaries of external limiting membrane loss (r = 0.933, P < 0.001).

Conclusions

SW-AF and NIR-AF revealed a characteristic sequence of AF patterns that correlated with functional and structural alterations, suggesting different stages in disease progression.

Translational Relevance

Alterations in NIR-AF exceeded those in SW-AF images, substantiating the hypothesis of different AF origins and suggesting NIR-AF as surrogate marker for early disease-related changes.

ElVisML: an open data format for the exchange and storage of electrophysiological data in ophthalmology

PURPOSE

The ISCEV standards and recommendations for electrophysiological recordings in ophthalmology define a set of protocols with stimulus parameters, acquisition settings, and recording conditions, to unify the data and enable comparability of results across centers. Up to now, however, there are no standards to define the storage and exchange of such electrophysiological recordings. The aim of this study was to develop an open standard data format for the exchange and storage of visual electrophysiological data (ElVisML).

METHODS

We first surveyed existing data formats for biomedical signals and examined their suitability for electrophysiological data in ophthalmology. We then compared the suitability of text-based and binary formats, as well as encoding in Extensible Markup Language (XML) and character/comma-separated values.

RESULTS

The results of the methodological consideration led to the development of ElVisML with an XML-encoded text-based format. This allows referential integrity, extensibility, the storing of accompanying units, as well as ensuring confidentiality and integrity of the data. A visualization of ElVisML documents (ElVisWeb) has additionally been developed, which facilitates the exchange of recordings on mailing lists and allows open access to data along with published articles.

CONCLUSIONS

The open data format ElVisML ensures the quality, validity, and integrity of electrophysiological data transmission and storage as well as providing manufacturer-independent access and long-term archiving in a future-proof format. Standardization of the format of such neurophysiology data would promote the development of new techniques and open software for the use of neurophysiological data in both clinic and research.

Structural and functional changes of the human macula during acute exposure to high altitude

Background

This study aimed to quantify structural and functional changes at the macula during acute exposure to high altitude and to assess their structure/function relationship. This work is related to the Tuebingen High Altitude Ophthalmology (THAO) study.

Methodology/Principal Findings

Spectral domain optical coherence tomography and microperimetry were used to quantify changes of central retinal structure and function in 14 healthy subjects during acute exposure to high altitude (4559 m). High-resolution volume scans and fundus-controlled microperimetry of the posterior pole were performed in addition to best-corrected visual acuity (BCVA) measurements and assessment of acute mountain sickness. Analysis of measurements at altitude vs. baseline revealed increased total retinal thickness (TRT) in all four outer ETDRS grid subfields during acute altitude exposure (TRT_outer = 2.80±1.00 μm; mean change±95%CI). This change was inverted towards the inner four subfields (TRT_inner = −1.89±0.97 μm) with significant reduction of TRT in the fovea (TRT_foveal = −6.62±0.90 μm) at altitude. BCVA revealed no significant difference compared to baseline (0.06±0.08 logMAR). Microperimetry showed stable mean sensitivity in all but the foveal subfield (MS_foveal = −1.12±0.68 dB). At baseline recordings before and >2 weeks after high altitude exposure, all subjects showed equal levels with no sign of persisting structural or functional sequels.

Conclusions/Significance

During acute exposure to high altitude central retinal thickness is subject to minor, yet statistically significant changes. These alterations describe a function of eccentricity with an increase in regions with relatively higher retinal nerve fiber content and vascular arcades. However, these changes did not correlate with measures of central retinal function or acute mountain sickness. For the first time a quantitative approach has been used to assess these changes during acute, non-acclimatized high altitude exposure.