Procedures—IOP measurements were obtained from each eye by use of both the rebound tonometer and applanation tonometer. Central corneal thickness was measured by use of an ultrasonic pachymeter 3 hours before surgery and 2 and 24 hours after surgery. Statistical analysis was performed by use of paired t tests.
Results—Mean ± SD IOP 3 hours before surgery, 2 hours after surgery, and 24 hours after surgery was 11.9 ± 4.7 mm Hg, 15.5 ± 11.7 mm Hg, and 10.9 ± 6.7 mm Hg, respectively, as measured with the rebound tonometer and 12.2 ± 5.3 mm Hg, 15.7 ± 12.5 mm Hg, and 12.4 ± 5.4 mm Hg, respectively, as measured with the applanation tonometer. Measured IOP did not differ significantly between the 2 tonometers 3 hours before surgery and 2 hours after surgery, but measured IOP differed significantly between the tonometers 24 hours after surgery.
Conclusions and Clinical Relevance—Use of a rebound tonometer underestimated IOP, relative to results for use of an applanation tonometer, by 1.65 mm Hg in eyes 24 hours after phacoemulsification. Caution should be used when IOP measurements obtained with a rebound tonometer are in the high part of the reference range, and verification of these values with an applanation tonometer would be advised.
Objective—To evaluate effects of intracameral injection
of preservative-free 1% and 2% lidocaine
hydrochloride solution on the anterior segment of the
eyes in dogs.
Animals—16 adult healthy dogs (8 male and 8
female) judged to be free of ocular disease.
Procedure—Dogs were randomly assigned to 2
groups of 8 dogs each. Group 1 dogs received an
intracameral injection of 0.10 mL of preservative-free
1% lidocaine solution in the designated eye, and
group 2 dogs received 0.10 mL of preservative-free
2% lidocaine solution in the designated eye. After
injection, intraocular pressure was measured every
12 hours for 48 hours and then every 24 hours until
168 hours after injection. Slit-lamp biomicroscopy was
performed preceding intracameral injection, 8 hours
after injection, and then every 24 hours until 168
hours after injection. Ultrasonic pachymetry and specular
microscopy were performed preceding intracameral
injection and 72 and 168 hours after injection.
Corneal thickness and endothelial cell density and
morphology were compared with baseline measurements.
Results—No significant differences were found in
intraocular pressure, corneal thickness, endothelial
cell density, and morphologic features in either group,
compared with baseline. A significant difference in
aqueous flare was found for treated and control eyes
8, 24, and 48 hours after injection, compared with
baseline. No significant difference in aqueous flare
was found between treated and control eyes within
Conclusions and Clinical Relevance—No adverse
ocular effects were detected after intracameral injection
of preservative-free 1% or 2% lidocaine solution;
thus, its use would be safe for intraocular pain management
in dogs. (Am J Vet Res 2004;65:1325–1330)
Objective—To determine the electrodiagnostic and
histologic response of short-term increases of
intraocular pressure (IOP) on transient pattern electroretinograms
(PERG) and flash electroretinograms
(FERG) in the eyes of dogs.
Animals—8 healthy mixed-breed dogs.
Procedure—Transient PERG and FERG waveforms
were recorded from dogs (while anesthetized) as IOP
was increased from baseline (7 to 19 mm Hg) to 90
mm Hg. One hundred mean PERG responses and a
single FERG response were recorded at each step
during 3 recording sessions. Globes of each dog were
enucleated after euthanasia on posttreatment day 7
and evaluated by a pathologist.
Results—Increases in spatial frequency resulted in
decreased amplitudes of N2 (second negative PERG
peak). Increases in IOP resulted in decreases in all 3
PERG waveforms and the FERG waveform. All values
began to return to baseline after short-term increases
in IOP on day 0, and waveforms were not significantly
different on posttreatment days 3 and 7.
Conclusions—Data suggest that short-term
increases in IOP affect PERG and FERG waveforms,
and PERG waveforms are more sensitive to increases
in IOP. Differences were not detected between
treated and control eyes on histologic examination.
Further studies are necessary to determine at what
IOP permanent damage to ganglion and photoreceptor
cells will develop and whether PERG is a reliable
clinical diagnostic technique for use in dogs to
reveal retinal damage that is secondary to increased
IOP prior to changes in waveforms generated by
FERG in dogs. (Am J Vet Res 2000;61:1087–1091)