TABLE 3.

Longitudinal OCT studies assessing retinal layers in PMS.

Study	Device	Cohort	Follow-up	Main findings
Talman et al., 2010	TD-OCT (OCT-3, Zeiss Meditec)	299 MS (84% RRMS)	1.5 years (range 0.5–4.5)	RNFLt reduction as a function of time (average −2.9 μm at 2–3 years and −6.1 μm at 3–4.5 years) in some patients with MS, even in the absence of aON
Henderson et al., 2010	TD-OCT (Stratus, Zeiss Meditec)	18 SPMS, 16 PPMS, 18 HC	1.5 years (range 1.1–2.4)	No significant RNFLt reduction over time in patients and controls. TMV decline in both groups, with no between-group differences
Balk et al., 2016	SD-OCT (Spectralis, Heidelberg Engineering)	7 CIS, 89 RRMS, 26 SPMS, 13 PPMS, 16 HC	2 years	RNFLt and GCIPLt reductions more pronounced early in the course of disease (higher atrophy rate in RRMS than SPMS patients)
Winges et al., 2019	SD-OCT (Cirrus 5000, Zeiss Meditec)	51 SPMS	2 years	RNFL (−0.31 μm/year) and GCIPL (−0.29 μm/year) atrophy rates similar in aON and nON eyes; RNFLt > 75 μm associated with higher (−0.85 μm/year) rate
Sotirchos et al., 2020	SD-OCT (Cirrus HD-OCT, Zeiss Meditec)	178 RRMS, 186 PMS, 66 HC	3.7 years (IQ range 2.0–5.9)	PMS phenotype associated with faster RNFLt (−0.34 %/year) and GCIPLt (−0.27 %/year) reduction; no significant impact determined by DMTs

TD-OCT, time domain–optical coherence tomography; SD-OCT, spectral domain–optical coherence tomography; CIS, clinically isolated syndrome; RRMS, relapsing–remitting multiple sclerosis; SPMS, secondary progressive multiple sclerosis; PPMS, primary progressive multiple sclerosis; HC, healthy controls; RNFLt, retinal nerve fiber layer thickness; TMV, total macular volume; GCIPLt, ganglion cells–inner plexiform layer thickness; aON, acute optic neuritis; nON, non-optic neuritis; DMTs, disease-modifying treatments.