Table 2. Distribution of retinal layer measurements from SD-OCT in NPC and controls.
A linear mixed model was used for statistical analysis. In the adjusted model, age, sex, and spherical equivalent were included.
| Macular OCT layers and ETDRS segments | Control eyes (n = 180) Mean (SD) [μm] | NPC eyes (n = 14) Mean (SD) [μm] | Crude model p-value | Adjusted model p-value |
|---|---|---|---|---|
| 1) NFL | ||||
| Fovea | 12.7 (2.1) | 11.9 (2.1) | 0.30 | 0.22 |
| Inner Ring | 21.7 (1.8) | 21.1 (1.5) | 0.50 | 0.44 |
| Outer Ring | 36.3 (4.0) | 37.7 (5.6) | 0.43 | 0.68 |
| 2) GCL | ||||
| Fovea | 16.1 (4.4) | 14.7 (3.8) | 0.35 | 0.12 |
| Inner Ring | 52.3 (4.2) | 52.6 (4.0) | 0.93 | 0.59 |
| Outer Ring | 35.9 (3.1) | 37.8 (2.8) | 0.31 | 0.49 |
| 3) IPL | ||||
| Fovea | 22.0 (3.7) | 20.8 (2.8) | 0.34 | 0.15 |
| Inner Ring | 42.7 (2.8) | 42.8 (2.8) | 0.88 | 0.71 |
| Outer Ring | 29.5 (2.5) | 31.0 (2.1) | 0.21 | 0.31 |
| 4) INL | ||||
| Fovea | 18.7 (4.6) | 15.9 (3.9) | 0.08 | 0.09 |
| Inner Ring | 40.3 (2.7) | 39.7 (3.6) | 0.58 | 0.44 |
| Outer Ring | 33.3 (2.4) | 34.7 (2.3) | 0.34 | 0.74 |
| 5) OPL | ||||
| Fovea | 26.2 (5.3) | 25.2 (5.0) | 0.59 | 0.37 |
| Inner Ring | 33.5 (3.8) | 33.4 (3.8) | 0.98 | 0.80 |
| Outer Ring | 27.1 (1.7) | 27.5 (1.8) | 0.50 | 0.39 |
| 6) ONL | ||||
| Fovea | 92.5 (10.3) | 80.4 (8.5) | 0.002 | 0.007 |
| Inner Ring | 72.2 (8.6) | 65.8 (5.5) | 0.06 | 0.10 |
| Outer Ring | 59.8 (6.5) | 55.9 (4.6) | 0.12 | 0.12 |
| 7) ORL (ELM to BM) | ||||
| Fovea | 90.6 (4.1) | 87.6 (4.6) | 0.027 | 0.010 |
| Inner Ring | 81.6 (2.3) | 80.3 (2.2) | 0.13 | 0.12 |
| Outer Ring | 78.3 (2.1) | 78.3 (2.0) | 0.96 | 0.98 |
| 7) RPE | ||||
| Fovea | 17.1 (1.8) | 16.9 (1.9) | 0.88 | 0.74 |
| Inner Ring | 14.8 (1.5) | 14.0 (1.6) | 0.15 | 0.38 |
| Outer Ring | 13.1 (1.2) | 12.9 (1.3) | 0.97 | 0.64 |
| Total retinal thickness | ||||
| Fovea | 278.3 (19.2) | 256.1 (21.1) | 0.003 | 0.001 |
| Inner Ring | 343.8 (12.8) | 334.9 (15.3) | 0.12 | 0.07 |
| Outer Ring | 306.9 (20.7) | 306.3 (17.2) | 0.79 | 0.60 |
SD-OCT = spectral domain optical coherence tomography, NPC = Niemann-Pick type C, ETDRS segments: OCT division scheme being named after the ‘Early Treatment Diabetic Retinopathy Study’, SD = standard deviation, NFL = nerve fibre layer, GCL = ganglion cell layer, IPL = inner plexiform layer, INL = inner nuclear layer, OPL = outer plexiform layer, ONL = outer nuclear layer, ORL = outer retinal layer (ELM = external limiting membrane, BM = Bruch’s membrane), RPE = retinal pigment epithelium, (I)1 = (inferior) inner ring, (I)2 = (inferior) outer ring.