Can subretinal microphotodiodes successfully replace degenerated photoreceptors?

The idea of implanting microphotodiode arrays as visual prostheses has aroused controversy on its feasibility from the moment it appeared in print. We now present results which basically support the concept of replacing damaged photoreceptors with subretinally implanted stimulation devices. Network activity in degenerated rat retinae could be modulated through local electrical stimulation in vitro.

The development of subretinal microphotodiodes for replacement of degenerated photoreceptors.

There are presently several concepts to restore vision in blind or highly visually handicapped persons by implanting electronic devices into the eye in order to partially restore vision. Here, the approach to replace retinal photoreceptors by a subretinally implanted microphotodiode array (MPDA) is summarized. A survey is given on the present state of the development of MPDAs, the possibility of in vitro and in vivo tests as well as first results on biocompatibility and histology.

[Incomplete congenital stationary night blindness (CSNB). An important differential diagnosis of congenital nystagmus].

Background: Classifying congenital nystagmus in the absence of biomicroscopically detectable abnormalities of the eye, and in an otherwise healthy child is difficult, especially early in life. At that age, nystagmus and visual loss may be the predominant symptoms of congenital stationary night-blindness. Unless night-blindness is specifically asked for or an ERG performed the correct diagnosis may be missed.

[Clinical electroretinography: standard protocol and normal values].

The International Standard of Clinical Electroretinography serves as standard protocol for recording electroretinographic responses in order to facilitate worldwide comparisons of examinations. To promote its distribution and acceptance throughout the German speaking countries, we established normal values for the five standard responses and added a German translation of the International Standard in the appendix. To determine normal values for electroretinographic data we suggest to use percentiles instead of parameters based on a Gaussian distribution.

Experiences with the international standard for clinical electroretinography: normative values for clinical practice, interindividual and intraindividual variations and possible extensions.

The international Standard for Clinical Electroretinography requires a minimum of 5 standard response types. In a sample of 20 healthy subjects, the normative values according to this standard were established. Since the distribution of amplitude and implicit time does not follow a Gaussian distribution, we have found the median value and the 1st to 99th percentile or the 5th to 95th percentile useful for determination of abnormality, presented here separately for intraindividual and interindividual variation.