144
D. Cabrera DeBuc et al.
The loss of retinal nerve fibers around the optic disc (cpRNFL) has been found
in the eyes of MS patients both with and without optic neuritis (ON) in the history [28, 112–119]. However, recent studies have shown that also macular thickness
and volume are decreased in the eyes of patients with MS [27, 28, 115, 120, 121],
presumably caused by the thinning of the GCL and IPL [33, 119, 121–123]. Objective markers might be necessary not only for the diagnosis but also the follow-up
of neuronal damage in MS, which could help to determine the effect of any possible therapeutic interventions in the future as well. Most of the published studies on
MS using OCT technology have assessed axonal damage by analyzing retinal thickness measurements. However, optical properties and texture measures of the retinal
tissue are also attractive parameters to consider in the overall evaluations. In what
follows we review the studies that considered both structural and optical properties
measurements.
6.3.2.1 Thickness Measurements
Tatrai et al. [13] evaluated the usefulness of macular OCT image segmentation in
patients with MS to determine the structural changes of the retina of MS patients.
Particularly, OCT examination was performed in thirty-nine patients with MS and in
thirty-three healthy subjects. In this study, the parameter which could discriminate
best the eyes of healthy subjects from the eyes of MS patients was also determined.
Their results showed that the thickness of the macular GCC had the highest sensitivity
and specificity to detect axonal loss independent of ON, outperforming the cpRNFL
thickness data provided by the analysis software of the commercially available Stratus
OCT device. A strong correlation with disease severity measured by the Expanded
Disability Status Scale (EDSS) score was also obtained in the case of the GCC
thickness which implies that this parameter might also be useful in the estimation
of disease progression as a surrogate marker. This study has also shown that ON
is followed by a targeted loss of ganglion cells in the macula which can also be
objectively assessed by quantitative analysis of OCT macular images.
Several studies have reported the atrophy of the RNFL around the optic disc
in patients with MS with and even without ON in medical history [28, 112–119].
Tatrai et al. [13] findings confirmed that the mean overall cpRNFL thickness and the
cpRNFL thickness in each quadrant is significantly lower in the eyes of MS patients
with a history of ON compared to the non-ON-affected eyes and also in comparison with healthy eyes except for the nasal quadrant (see Fig. 6.4.). However, their
results showed that in the non-affected eyes of MS patients the cpRNFL thickness
is decreased only in the temporal quadrant compared to healthy eyes. Furthermore,
the most pronounced reduction in the thickness of cpRNFL (27 and 17% in the
ON-affected and non-affected eyes, respectively) was also observed in the temporal
quadrant. These findings agree with previous OCT studies confirming that the fibers
of the papillomacular bundle are the most susceptible to damage in ON [117, 124].
One important aspect of this fact, as it has been widely reported in glaucomatous
damage, is that the evaluation of the sectoral thickness values could provide the pos-
D. Cabrera DeBuc et al.
The loss of retinal nerve fibers around the optic disc (cpRNFL) has been found
in the eyes of MS patients both with and without optic neuritis (ON) in the history [28, 112–119]. However, recent studies have shown that also macular thickness
and volume are decreased in the eyes of patients with MS [27, 28, 115, 120, 121],
presumably caused by the thinning of the GCL and IPL [33, 119, 121–123]. Objective markers might be necessary not only for the diagnosis but also the follow-up
of neuronal damage in MS, which could help to determine the effect of any possible therapeutic interventions in the future as well. Most of the published studies on
MS using OCT technology have assessed axonal damage by analyzing retinal thickness measurements. However, optical properties and texture measures of the retinal
tissue are also attractive parameters to consider in the overall evaluations. In what
follows we review the studies that considered both structural and optical properties
measurements.
6.3.2.1 Thickness Measurements
Tatrai et al. [13] evaluated the usefulness of macular OCT image segmentation in
patients with MS to determine the structural changes of the retina of MS patients.
Particularly, OCT examination was performed in thirty-nine patients with MS and in
thirty-three healthy subjects. In this study, the parameter which could discriminate
best the eyes of healthy subjects from the eyes of MS patients was also determined.
Their results showed that the thickness of the macular GCC had the highest sensitivity
and specificity to detect axonal loss independent of ON, outperforming the cpRNFL
thickness data provided by the analysis software of the commercially available Stratus
OCT device. A strong correlation with disease severity measured by the Expanded
Disability Status Scale (EDSS) score was also obtained in the case of the GCC
thickness which implies that this parameter might also be useful in the estimation
of disease progression as a surrogate marker. This study has also shown that ON
is followed by a targeted loss of ganglion cells in the macula which can also be
objectively assessed by quantitative analysis of OCT macular images.
Several studies have reported the atrophy of the RNFL around the optic disc
in patients with MS with and even without ON in medical history [28, 112–119].
Tatrai et al. [13] findings confirmed that the mean overall cpRNFL thickness and the
cpRNFL thickness in each quadrant is significantly lower in the eyes of MS patients
with a history of ON compared to the non-ON-affected eyes and also in comparison with healthy eyes except for the nasal quadrant (see Fig. 6.4.). However, their
results showed that in the non-affected eyes of MS patients the cpRNFL thickness
is decreased only in the temporal quadrant compared to healthy eyes. Furthermore,
the most pronounced reduction in the thickness of cpRNFL (27 and 17% in the
ON-affected and non-affected eyes, respectively) was also observed in the temporal
quadrant. These findings agree with previous OCT studies confirming that the fibers
of the papillomacular bundle are the most susceptible to damage in ON [117, 124].
One important aspect of this fact, as it has been widely reported in glaucomatous
damage, is that the evaluation of the sectoral thickness values could provide the pos-