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Comparison of longitudinal in vivo measurements of retinal nerve fiber layer thickness and retinal ganglion cell density after optic nerve transection in rat.

Choe TE, Abbott CJ, Piper C, Wang L, Fortune B - PLoS ONE (2014)

Bottom Line: RGCs were labeled by retrograde transport of fluorescently conjugated cholera toxin B (CTB) from the superior colliculus 48 hours prior to ONT or sham surgery.In ONT-CTB labeled fellow eyes, RNFLT increased by 18%, 52% and 36% at weeks 2, 3 and 4 (p<0.0001), but did not change in fellow ONT-eyes sans CTB.The strong fellow eye effect observed in eyes contralateral to ONT, only in the presence of CTB label, consisted of a dramatic increase in RNFLT associated with retinal microgliosis.

View Article: PubMed Central - PubMed

Affiliation: Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America.

ABSTRACT

Purpose: To determine the relationship between longitudinal in vivo measurements of retinal nerve fiber layer thickness (RNFLT) and retinal ganglion cell (RGC) density after unilateral optic nerve transection (ONT).

Methods: Nineteen adult Brown-Norway rats were studied; N = 10 ONT plus RGC label, N = 3 ONT plus vehicle only (sans label), N = 6 sham ONT plus RGC label. RNFLT was measured by spectral domain optical coherence tomography (SD-OCT) at baseline then weekly for 1 month. RGCs were labeled by retrograde transport of fluorescently conjugated cholera toxin B (CTB) from the superior colliculus 48 hours prior to ONT or sham surgery. RGC density measurements were obtained by confocal scanning laser ophthalmoscopy (CSLO) at baseline and weekly for 1 month. RGC density and reactivity of microglia (anti-Iba1) and astrocytes (anti-GFAP) were determined from post mortem fluorescence microscopy of whole-mount retinae.

Results: RNFLT decreased after ONT by 17% (p<0.05), 30% (p<0.0001) and 36% (p<0.0001) at weeks 2, 3 and 4. RGC density decreased after ONT by 18%, 69%, 85% and 92% at weeks 1, 2, 3 and 4 (p<0.0001 each). RGC density measured in vivo at week 4 and post mortem by microscopy were strongly correlated (R = 0.91, p<0.0001). In vivo measures of RNFLT and RGC density were strongly correlated (R = 0.81, p<0.0001). In ONT-CTB labeled fellow eyes, RNFLT increased by 18%, 52% and 36% at weeks 2, 3 and 4 (p<0.0001), but did not change in fellow ONT-eyes sans CTB. Microgliosis was evident in the RNFL of the ONT-CTB fellow eyes, exceeding that observed in other fellow eyes.

Conclusions: In vivo measurements of RNFLT and RGC density are strongly correlated and can be used to monitor longitudinal changes after optic nerve injury. The strong fellow eye effect observed in eyes contralateral to ONT, only in the presence of CTB label, consisted of a dramatic increase in RNFLT associated with retinal microgliosis.

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Longitudinal measurements of RNFLT for all three experimental groups.Values of RNFLT were normalized to the baseline average of each eye; symbols represent the group average, error bars indicate SEM. RNFLT decreased in Group-1 ONT eyes by 17%, 30% and 36% at weeks 2, 3 and 4. Group 2 operated eyes (“ONT sans CTB”) exhibited a similar pattern of longitudinal RNFLT change. In Group-1 ONT fellow eyes, RNFLT increased by 18%, 52% and 36% at weeks 2, 3 and 4. There were no significant differences from baseline for any group at week-1. There was no significant change in RNFLT at any follow-up time point in Group-2 non-operated fellow control eyes (“ONT sans CTB Fellow”), Group-3 sham operated (“Sham”) or Group-3 fellow control eyes (“Sham Fellow”). *Significant change from baseline assessed by two-way repeated measures ANOVA with Bonferroni post-hoc tests on raw values (see text for details).
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pone-0113011-g002: Longitudinal measurements of RNFLT for all three experimental groups.Values of RNFLT were normalized to the baseline average of each eye; symbols represent the group average, error bars indicate SEM. RNFLT decreased in Group-1 ONT eyes by 17%, 30% and 36% at weeks 2, 3 and 4. Group 2 operated eyes (“ONT sans CTB”) exhibited a similar pattern of longitudinal RNFLT change. In Group-1 ONT fellow eyes, RNFLT increased by 18%, 52% and 36% at weeks 2, 3 and 4. There were no significant differences from baseline for any group at week-1. There was no significant change in RNFLT at any follow-up time point in Group-2 non-operated fellow control eyes (“ONT sans CTB Fellow”), Group-3 sham operated (“Sham”) or Group-3 fellow control eyes (“Sham Fellow”). *Significant change from baseline assessed by two-way repeated measures ANOVA with Bonferroni post-hoc tests on raw values (see text for details).

Mentions: Figure 1 shows the results in a single representative animal of RNFLT measured longitudinally by SD-OCT before and after unilateral ONT. As expected, RNFLT decreased steadily in the weeks after ONT (left column), however somewhat surprisingly, there was a substantial increase in RNFLT in the fellow eye during the second, third and fourth weeks of post-operative follow-up (right column). In this individual, there was also a small increase in RNFLT as well as an increase in the apparent intensity of RNFL reflectivity1-week after ONT, a finding that was not consistent enough across Group-1 ONT eyes to be statistically significant (group average change at week-1 was 3.5% increase over baseline average, p>0.05, see Fig. 2).


Comparison of longitudinal in vivo measurements of retinal nerve fiber layer thickness and retinal ganglion cell density after optic nerve transection in rat.

Choe TE, Abbott CJ, Piper C, Wang L, Fortune B - PLoS ONE (2014)

Longitudinal measurements of RNFLT for all three experimental groups.Values of RNFLT were normalized to the baseline average of each eye; symbols represent the group average, error bars indicate SEM. RNFLT decreased in Group-1 ONT eyes by 17%, 30% and 36% at weeks 2, 3 and 4. Group 2 operated eyes (“ONT sans CTB”) exhibited a similar pattern of longitudinal RNFLT change. In Group-1 ONT fellow eyes, RNFLT increased by 18%, 52% and 36% at weeks 2, 3 and 4. There were no significant differences from baseline for any group at week-1. There was no significant change in RNFLT at any follow-up time point in Group-2 non-operated fellow control eyes (“ONT sans CTB Fellow”), Group-3 sham operated (“Sham”) or Group-3 fellow control eyes (“Sham Fellow”). *Significant change from baseline assessed by two-way repeated measures ANOVA with Bonferroni post-hoc tests on raw values (see text for details).
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4231142&req=5

pone-0113011-g002: Longitudinal measurements of RNFLT for all three experimental groups.Values of RNFLT were normalized to the baseline average of each eye; symbols represent the group average, error bars indicate SEM. RNFLT decreased in Group-1 ONT eyes by 17%, 30% and 36% at weeks 2, 3 and 4. Group 2 operated eyes (“ONT sans CTB”) exhibited a similar pattern of longitudinal RNFLT change. In Group-1 ONT fellow eyes, RNFLT increased by 18%, 52% and 36% at weeks 2, 3 and 4. There were no significant differences from baseline for any group at week-1. There was no significant change in RNFLT at any follow-up time point in Group-2 non-operated fellow control eyes (“ONT sans CTB Fellow”), Group-3 sham operated (“Sham”) or Group-3 fellow control eyes (“Sham Fellow”). *Significant change from baseline assessed by two-way repeated measures ANOVA with Bonferroni post-hoc tests on raw values (see text for details).
Mentions: Figure 1 shows the results in a single representative animal of RNFLT measured longitudinally by SD-OCT before and after unilateral ONT. As expected, RNFLT decreased steadily in the weeks after ONT (left column), however somewhat surprisingly, there was a substantial increase in RNFLT in the fellow eye during the second, third and fourth weeks of post-operative follow-up (right column). In this individual, there was also a small increase in RNFLT as well as an increase in the apparent intensity of RNFL reflectivity1-week after ONT, a finding that was not consistent enough across Group-1 ONT eyes to be statistically significant (group average change at week-1 was 3.5% increase over baseline average, p>0.05, see Fig. 2).

Bottom Line: RGCs were labeled by retrograde transport of fluorescently conjugated cholera toxin B (CTB) from the superior colliculus 48 hours prior to ONT or sham surgery.In ONT-CTB labeled fellow eyes, RNFLT increased by 18%, 52% and 36% at weeks 2, 3 and 4 (p<0.0001), but did not change in fellow ONT-eyes sans CTB.The strong fellow eye effect observed in eyes contralateral to ONT, only in the presence of CTB label, consisted of a dramatic increase in RNFLT associated with retinal microgliosis.

View Article: PubMed Central - PubMed

Affiliation: Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America.

ABSTRACT

Purpose: To determine the relationship between longitudinal in vivo measurements of retinal nerve fiber layer thickness (RNFLT) and retinal ganglion cell (RGC) density after unilateral optic nerve transection (ONT).

Methods: Nineteen adult Brown-Norway rats were studied; N = 10 ONT plus RGC label, N = 3 ONT plus vehicle only (sans label), N = 6 sham ONT plus RGC label. RNFLT was measured by spectral domain optical coherence tomography (SD-OCT) at baseline then weekly for 1 month. RGCs were labeled by retrograde transport of fluorescently conjugated cholera toxin B (CTB) from the superior colliculus 48 hours prior to ONT or sham surgery. RGC density measurements were obtained by confocal scanning laser ophthalmoscopy (CSLO) at baseline and weekly for 1 month. RGC density and reactivity of microglia (anti-Iba1) and astrocytes (anti-GFAP) were determined from post mortem fluorescence microscopy of whole-mount retinae.

Results: RNFLT decreased after ONT by 17% (p<0.05), 30% (p<0.0001) and 36% (p<0.0001) at weeks 2, 3 and 4. RGC density decreased after ONT by 18%, 69%, 85% and 92% at weeks 1, 2, 3 and 4 (p<0.0001 each). RGC density measured in vivo at week 4 and post mortem by microscopy were strongly correlated (R = 0.91, p<0.0001). In vivo measures of RNFLT and RGC density were strongly correlated (R = 0.81, p<0.0001). In ONT-CTB labeled fellow eyes, RNFLT increased by 18%, 52% and 36% at weeks 2, 3 and 4 (p<0.0001), but did not change in fellow ONT-eyes sans CTB. Microgliosis was evident in the RNFL of the ONT-CTB fellow eyes, exceeding that observed in other fellow eyes.

Conclusions: In vivo measurements of RNFLT and RGC density are strongly correlated and can be used to monitor longitudinal changes after optic nerve injury. The strong fellow eye effect observed in eyes contralateral to ONT, only in the presence of CTB label, consisted of a dramatic increase in RNFLT associated with retinal microgliosis.

Show MeSH
Related in: MedlinePlus