Laser speckle and hydrogen gas clearance measurements of optic nerve circulation in albino and pigmented rabbits with or without optic disc atrophy.
OBJECTIVE
The purpose of this study was to evaluate the correlation between laser speckle flowgraphy measurements of mean blur rate (MBR) and hydrogen gas clearance measurements of capillary blood flow (CBF) in the optic nerve head (ONH) of albino and pigmented rabbits, with or without chronic ischemia-induced ONH atrophy.


METHODS
The ONH MBR and ONH CBF were measured at baseline, 30 and 60 minutes after the intravenous administration of endothelin-1 (ET-1) (10(-10) mol/kg) in six albino and six pigmented rabbit eyes. The ONH MBR and ONH CBF were also measured in nine pigmented rabbit eyes that underwent the intravitreal administration of ET-1 (20 pmol) twice per week for 4 weeks to provoke chronic ischemia-induced ONH atrophy.


RESULTS
In the group that received intravenous ET-1, average measurements of ONH MBR and ONH CBF at all time points were correlated in both the albino (r = 0.88, P < 0.001, n = 18) and pigmented rabbits (r = 0.85, P < 0.001, n = 18), with no intrarabbit correlations (P = 0.524). The ONH MBR and ONH CBF were also correlated in the model of chronic ischemia-induced ONH atrophy (r = 0.78, P = 0.013, n = 9). Pooled ONH MBR and ONH CBF measurements in both the intravenous and intravitreal groups were also highly correlated (r = 0.87, P < 0.001, n = 45), with no significant intergroup differences in the relationship between ONH MBR and ONH CBF (P = 0.138).


CONCLUSIONS
Regardless of the presence of fundus pigmentation or ONH atrophy, ONH MBR and ONH CBF were highly correlated, suggesting that MBR in the ONH tissue is usable for interindividual and intergroup comparisons.
Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan.
Naoko
N
Aizawa
Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan.
Fumihiko
F
Nitta
Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Sendai, Japan.
Hiroshi
H
Kunikata
Nakano Eye Clinic of Kyoto Medical Co-operative, Kyoto, Japan.
Tetsuya
T
Sugiyama
Department of Ophthalmology, Osaka Medical College, Osaka, Japan.
Tsunehiko
T
Ikeda
Department of Ophthalmology, Kanto Central Hospital of The Mutual Aid Association of Public School Teachers, Tokyo, Japan.
Makoto
M
Araie
Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan Department of Retinal Disease Control, Tohoku University Graduate School of Medicine, Sendai, Japan Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
Toru
T
Nakazawa
D000704:Analysis of Variance; D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects / Q000502:physiology; D002196:Capillaries / Q000502:physiology; D004195:Disease Models, Animal; D019332:Endothelin-1 / Q000494:pharmacology; D006859:Hydrogen; D017078:Laser-Doppler Flowmetry / Q000379:methods*; D008297:Male; D008833:Microcirculation / Q000187:drug effects / Q000502:physiology; D009896:Optic Atrophy / Q000503:physiopathology*; D009898:Optic Disk / Q000098:blood supply*; D011817:Rabbits; D012039:Regional Blood Flow
D019332:Endothelin-1; D006859:Hydrogen
capillary blood flow; endothelin-1; laser speckle flowgraphy; mean blur rate; optic nerve head