All animals were chemically restrained using 10 mg/kg ketamine HCl
intramuscularly. Once restrained, 0.16 mg atropine sulfate was
administered subcutaneously. Two drops each of proparacaine HCl 0.5% ,
phenylephrine HCl 2.5%, and tropicamide 1% were administered to both
eyes. Under ketamine restraint, the primate had intravenous catheters
placed for administration of warmed lactated Ringer’s solution
(10-ml/kg per hour flow rate) and for administration of propofol. An
initial induction dose of propofol (5 mg/kg) was administered to
effect. The state of anesthesia was maintained in the subject by
administering 0.2 to 0.5 mg/kg per minute propofol by syringe pump. The
animal was intubated with a cuffed endotracheal tube. A peribulbar
injection of 2% lidocaine was administered to reduce extraocular
muscular movement. The subject was securely restrained prone on an
adjustable stage for fundus photography, laser exposure, and FA.
Immediately before FA, 0.6 ml Fluorescite 10% (Alcon, Fort Worth, TX)
was administered as an intravenous bolus. The subject’s blood
pressure, temperature, and pulse were continuously monitored throughout
the experimental protocol. Normal body temperature was maintained by
the use of circulating warm water blankets.
The eyelids were held open with a wire lid speculum, and the cornea was
moistened throughout the procedures with 0.9% saline solution. The
retina was viewed with a modified fundus camera at all times, and all
macular exposures (15–30) were delivered to the eye, without an
external lens system, in a rectangular grid pattern in the macular
region of the fundus. Immediately visible retinal marker lesions
(created by shuttered exposures of the mode-locked, doubled, compressed
Nd:YAG output at 82 MHz for the three longer pulse widths and a 3-msec
shuttered exposure of krypton laser output for the 1-psec and 150-fsec
pulses) were made in an L-shaped grid pattern of columns and rows to
aid in localizing the exposure sites. Fundus photography (including FA)
and observation of lesion formation by the researchers were performed
by monocular viewing through a fundus camera’s optical system (Zeiss
or Topcon). Photographs of the fundus were taken immediately before the
dye injection, during fluorescein angiography, and at intervals of a
few seconds until 5 minutes had elapsed, thus providing a sequence of
photographs for the development of fluorescein leakage. After
fluorescein injection and angiography, the lesions were also assessed
for fluorescence by viewing through the camera system with excitation
and a barrier filter in place. However, fluorescein leakage for the
smaller lesions could not be identified by direct observation through
the fundus camera, and no results using this technique are reported in
this article.
A minimum of two examiners evaluated all eyes at 1 hour and 24 hours
after exposure. Visible lesions at a given exposure site were reported
to be present only if two or more\E
examiners identified a lesion. Color fundus photographs were taken at 1
hour and 24 hours after exposure, along with black-and-white
photographs of the FA.