A new DTL-electrode holder for recording of electroretinograms in animals.

PURPOSE: Contact lens electrodes (CLEs) are frequently used to register electroretinograms (ERGs) in small animals such as mice or rats. CLEs are expensive to buy or difficult to be produced individually. In addition, CLE's have been noticed to elicit inconstant results and they carry potential to injure the cornea. Therefore, a new electrode holder was constructed based on the clinically used DTL-electrode and compared to CLEs. MATERIAL AND METHODS: ERGs were recorded with both electrode types in nine healthy Brown-Norway rats under scotopic conditions. For low intensity responses a Naka-Rushton function was fitted and the parameters V(max), k and n were analyzed. The a-wave, b-wave and oscillatory potentials were analyzed for brighter flash intensities (1-60 scot cds/m²). Repeatability was assessed for both electrode types in consecutive measurements. RESULTS: The new electrode holder was faster in setting up than the CLE and showed lower standard deviations. No corneal alterations were observed. Slightly higher amplitudes were recorded in most of the measurements with the new electrode holder (except amplitudes induced by 60 cds/m²). A Bland-Altman test showed good agreement between the DTL holder and the CLE (mean difference 35.2 µV (Holder-CLE)). Pearson's correlation coefficient for test-retest-reliability was r=0.783. CONCLUSIONS: The DTL holder was superior in handling and caused far less corneal problems than the CLE and produced comparable or better electrophysiological results. The minimal production costs and the possibility of adapting the DTL holder to bigger eyes, such as for dogs or rabbits, offers with broader application prospects.

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

Various morphological and functional techniques for retina examination have been established in the recent years. Although many examination results are spatially resolved and can be mapped onto data originating from other modalities, usually only data from one modality is analyzed by a clinician at a time. This is mainly because there is no software available to the public that enables the registration of structure and function in the clinical setting. Therefore we developed an integrated mapping application that allows the registration and analysis of morphological data (fundus photography, optical coherence tomography, scanning laser ophthalmoscopy images, and GDx thickness profiles) and functional data (multifocal electroretinography, multifocal pattern electroretinography, perimetry, and microperimetry). To obtain quantitative data that can be used for clinical trials and statistical analyses, extraction routines for morphological parameters - such as retinal layer thicknesses and measures of the vascular network - have been integrated. Global, regional and point-specific data from registered modalities can be extracted and exported for statistical analyses. In this article we present the implementation and examples of use of the developed software.

Multimodal multidimensional imaging for visual system status assessment.

Non-invasive optical methods that enable in vivo or in situ visualization of tissue components are of particular relevance in ophthalmology, as they can provide key information about the relationship between the structure and function of the visual system. In this paper we present a semiautomated multimodal imaging tool for co-registration of images of retinal structure and its function, based on point correspondence. Decision support analysis was applied to define significant features for the multimodal mapping system, using a set of 1500 subjects who were affected by blindness associated hereditary retinal dystrophies. Additionally, the developed software was tested by two experienced observers using data from 25 subjects. Inter-observer and intra-observer reliability was determined. We conclude that semi-automated multimodal mapping could be a promising new tool for an individualized visual system status assessment that can be applied for the early diagnosis of blindness associated diseases. Moreover, this mapping approach should prove particularly appropriate for studying pathophysiology in inherited blindness associated diseases.