Longitudinal profile of retinal ganglion cell damage after optic nerve crush with blue-light confocal scanning laser ophthalmoscopy.
OBJECTIVE
To investigate the long-term longitudinal profile of retinal ganglion cell (RGC) damage after optic nerve crush with a new technique for in vivo imaging of RGCs.


METHODS
A blue-light confocal scanning laser ophthalmoscope (bCSLO; 460 nm excitation, 490 nm detection) was used to image Thy-1 CFP mice aged 6 to 9 months (n = 5) before optic nerve crush, weekly after crush for 3 weeks, and at weeks 10 and 50 after optic nerve crush. A sham procedure was performed in the contralateral eye, and it was imaged as a control. Corresponding retinal areas before and after optic nerve crush were compared, and the fluorescent spots were counted manually. The longitudinal profile of RGC degeneration was modeled and compared with one-phase and two-phase exponential decay equations.


RESULTS
A significant and progressive loss of fluorescent spots was found after optic nerve crush with 18.6% +/- 2.3%, 11.3% +/- 3.4%, 8.8% +/- 5.3%, 4.2% +/- 3.1%, and 3.3% +/- 2.1% of Thy-1-expressing RGCs remaining at weeks 1, 2, 3, 10, and 50, respectively, after optic nerve crush (P < 0.001; n = 5). There was no change in the fluorescence density in the contralateral control (P = 0.893). Two-phase exponential decay (y = 0.03 + 0.83e(-)(2.78t) + 0.14e(-)(0.30t)) was a better fit than one-phase exponential decay (y = 0.94e(-)(1.93t) + 0.06; P = 0.003) equations, with half-lives of fast phase and slow phase of 1.7 days and 16.3 days, respectively.


CONCLUSIONS
The longitudinal profile of RGC degeneration after optic nerve crush is characterized by a two-phase exponential decay model. bCSLO imaging provides an efficient and noninvasive approach to the longitudinal study of progressive RGC damage.
Leung
Christopher Kai-shun
CK
Department of Ophthalmology, Hamilton Glaucoma Center, University of California San Diego, La Jolla, California 92093-0946, USA.
Lindsey
James D
JD
Crowston
Jonathan G
JG
Lijia
Chen
C
Chiang
Sylvia
S
Weinreb
Robert N
RN
D000818:Animals; D004195:Disease Models, Animal; D018450:Disease Progression; D005451:Fluorescein Angiography; D005500:Follow-Up Studies; D005654:Fundus Oculi; D051379:Mice; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D009887:Ophthalmoscopy / Q000379:methods*; D020221:Optic Nerve Injuries / Q000150:complications / Q000175:diagnosis*; D015203:Reproducibility of Results; D012164:Retinal Diseases / Q000175:diagnosis* / Q000209:etiology; D012165:Retinal Ganglion Cells / Q000473:pathology*; D013997:Time Factors; D041623:Tomography, Optical Coherence / Q000379:methods*