INVESTIGADORES
DORFMAN Damian
congresos y reuniones científicas
Título:
Study of Radial Optic Neurotomy Outcomes in Normal Rat Eyes
Autor/es:
DORFMAN D; CROXATTO JO; DE ZAVALÍA N; ROSENSTEIN RE; BELFORTE NA
Lugar:
Fort Lauderdale
Reunión:
Congreso; Association For Research In Vision And Ophthalmology (Arvo); 2010
Institución organizadora:
Association For Research In Vision And Ophthalmology (Arvo)
Resumen:
Purpose
Radial optic neurotomy (RON) consists in the surgical dissection of
the lamina cribrosa transvitreally via a radial incision on
the nasal side of the optic nerve. RON was proposed as a surgical
treatment for central retinal vein occlusion (CRVO). Although
improvements in visual acuity by RON in patients with CRVO have been
confirmed by several investigators, it is still controversial
whether the incision of the scleral outlet is a reasonable or
dangerous procedure. The use of rodents allows experimentation with
sufficient number of animals and could provide a picture of both
functional and morphological consequences of RON. Therefore, the aim
of the present report was to analyze RON outcomes in normal rat
eyes.
Methods
Male Wistar rats were subjected to RON in one eye, whereas thecontralateral eye was subjected to a sham procedure. RON was performed
as follows: eyes were focused under a binocular Colden surgical
microscope with coaxial light and a scleral puncture, using a 30-G
needle, was made at 1 mm of the corneoscleral limbus and a cut was
performed in the edge of the neuro-retinal ring, cutting an equal
part of optic nerve and retina parapapillary, avoiding the central
retinal vessels. The sham operated eyes were submitted to a similar
procedure, without the cutting step. After surgery, the surgical
outcomes were evaluated in terms of: IOP (assessed by a TonoPen XL),
flash electroretinograms (ERG, with a gold electrode), flash visual
evoked potential (VEPs, using skull-implanted electrodes) and
consensual pupil light reflex assessment, as well as optic nerve
head morphology (examined by light microscopy).
Results
A transient decrease in scotopic ERG a- and b-wave amplitude was
observed in eyes submitted to RON, which was evident 24 h but not 3
or 7 days after surgery. No changes in flash VEPs, IOP, and
consensual pupil reflex were observed between sham and RON operated
eyes at 7-day post-surgery. Histologically, the optic nerve showed
circumscribed scarring at the site of the incision without
significant damage of adjacent nerve fibers.
Conclusions
These results support that minor histological alterations and transient
functional changes were provoked by RON in normal rat eyes.