Purchase this article with an account.
H. Zwick, C. DiCarlo, B.E. Stuck, D.J. Lund; MFERG Analysis of Longterm Laser Induced Retinal Injury in the Non-Human Primate . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4929.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose To evaluate laser induced retinal nerve fiber layer (RNFL) and intraretinal scar formation (IRSF) with multifocal electroretinography (mfERG) in a non-human primate (NHP) model. Methods Secondary damage effects (RNFL and IRSF) were induced in six NHPs (macaca mulatta) with q-switched single pulse Neodymium (1064 nm, 1.0 mJ) or Argon CW ( 10 to 1000 msec,10-150mJ ) for single and multiple pulse exposures . A Veris (4.9) mfERG system (103 Hexagons, centered macula, 0 magnification) permitted continuous monitoring of the optic disk and choroidal nonsensory retina. Previous images of post exposure RNFL and IRSF retinal damage sites were available for each NHP for comparison with mfERG. Chemical restraint was achieved using Ketamine HCL (10 mg/kg IM) and Propofol (0.5 mg-1.2 mg/kg/min via syringe pump). Peribulbar eye blocks for ocular stability were performed using 2% Lidocaine or a mixture of 2% Lidocaine/Marcaine. Results Measurements of mfERG in eyes with well defined RNFL and IRSF damage demonstrated local alterations in mfERG waveforms characterized by deeper N2 components relative to non-exposed NHP mfERG measurements. More generalized loss of specificity was observed in the exposed group of NHPs for the second order mfERG kernal (first slice) relative to non-exposed NHPs. Acute exposure demonstrated a delay in the development of inner retinal dysfunction, requiring about 1 week post exposure to develop. Focality of the first order kernal measurements was also demonstrated by minimal loss in macular (central) mfERG waveforms and similar results for second order kernal, first slice measurements. Conclusions The ability of the mfERG to detect retinal injury with well defined inner retinal damage components was demonstrated. First and second order kernals demonstrated this ability with less specificity for second order components. Where the acute injury phase of RNFL could be followed, early dysfunction (post 30 min) involved less inner retinal contributions than at 1 week post, consistent with morphological delay in RNFL damage development (Frisch et al Nature,1974,248,433). In contrast, longterm RNFL or inner retinal dysfunction failed to completely match morphological based injury metrics (OCT, CSLO) and may reflect longterm repair, neural reorganization or weaker diagnostic capability. Nevertheless, where central retina had been spared of RNFL or IRSF damage, normal macula function was reasonably preserved, indicating the ability of mfERG to differentiate focal laser induced damage effects external to the macula based on inner retinal dysfunction.
This PDF is available to Subscribers Only