Regional Distribution of Choroidal Thickness and Diurnal Variation in Choroidal Thickness and Axial Length in Young Adults

Figures & data

Figure 1 Vertical (A) and horizontal (B) single line image obtained with optical coherence tomography (OCT) instrument, the foveal pit as manually marked in the custom-written software (straight red line in (A and B), the anterior (green line in (A and B) and posterior (blue line in (A and B) are the boundaries of the choroid.

Table 1 Participant Demographic Data and Ocular Characteristics

	Mean ± SD	Range
Age (year)	25.18 ± 2.77	18–35
Distance best corrected VA (logMAR)	−0.06 ± 0.08	−0.1 – +0.1
Average corneal curvature (D)	43.46 ± 1.44	39.34–46.64
Central spherical equivalent refractive error (D)
All subjects (n = 34)	−3.65 ± 3.07	−10.54 – +0.02
Emmetrope (n = 6)	−0.20 ± 0.12	−0.40 – +0.02
Myope (n = 16)	−2.48 ± 1.30	−5.88 – −0.59
High myope (n = 12)	−7.60 ± 1.58	−10.54 – −6.21
Axial length (mm)
All subjects (n = 34)	24.85 ± 1.18	22.49–27.20
Emmetrope (n = 6)	23.51 ± 0.76	22.49–24.66
Myope (n = 16)	24.63 ± 0.87	22.97–25.97
High myope (n = 12)	26.03 ± 0.61	25.26–27.20

Table 2 Overview of Mean Choroidal Thickness Across Measured Regions

	Mean ± SD Choroidal Thickness (µm)
	All Subjects (n = 34)	Emmetropes (n = 6)	Myopes (n = 16)	High Myopes (n = 12)
Overall thickness	257 ± 81	258 ± 73	264 ± 78	237 ± 48 *^†
Eccentricity
Fovea (0.5 mm)	271 ± 83	297 ± 57	286 ± 72	231 ± 36*^†
Parafovea (1 mm)	269 ± 81	287 ± 62	284 ± 74	237 ± 40*^†
Perifovea (1 mm)	259 ± 82	262 ± 69	272 ± 81	242 ± 50^†
Near-periphery (1.5 mm)	240 ± 83	231 ± 79	251 ± 84*	237 ± 61
Periphery (2 mm)	225 ± 63	210 ± 71	227 ± 62	239 ± 46
Quadrant
Superior	277 ± 73	273 ± 62	292 ± 69	266 ± 47^†
Temporal	262 ± 74	275 ± 59	263 ± 72	248 ± 38
Inferior	255 ± 80	252 ± 75	276 ± 78*	238 ± 37^†
Nasal	218 ± 89	231 ± 93	226 ± 82	198 ± 44*^†

Notes: *Significantly thinner choroid in the refractive group compared to the emmetropic group (p < 0.05) with adjustment for multiple comparisons (Bonferroni). ^†Significantly thinner choroid in the high myopic refractive group compared to the myopic group (p < 0.05) with adjustment for multiple comparisons (Bonferroni).

Figure 2 Mean choroidal thickness (μm) a across different quadrants as a function of eccentricity in emmetropic (A), myopic (B), and high myopic eyes (C). Error bars represents standard error of the mean. Single asterisks (*) indicate a statistically significant difference (p < 0.05) between the superior and the other quadrants. Filled symbols represent a statistically significant difference (p < 0.05) in a given choroidal eccentricity compared to the adjacent eccentricity to the left.

Table 3 Overview of the Diurnal Variation Amplitude in Axial Length and Choroidal Thickness in the Three Myopic Refractive Groups

	Mean ± SD Diurnal Variation Amplitude (µm)
	All Subjects (n = 34)	Emmetropes (n = 6)	Myopes (n = 16)	High Myopes (n = 12)
Axial length	17.8 ± 11	21.3 ± 8.5	18.8 ± 9.7	14.5 ± 12.7*^†
Choroidal thickness (ChT)	17.6 ± 15	21.4 ± 15	19.0 ± 17	14.6 ± 11*^†
ChT: Eccentricity
Fovea (0.5 mm)	18.5 ± 15	23 ± 15	19 ± 17	13 ± 10*^†
Parafovea (1 mm)	18.8 ± 15	24 ± 15	20 ± 17	13 ± 8*^†
Perifovea (1 mm)	18.9 ± 14	23 ± 16	18 ± 14	15 ± 12
Near-periphery (1.5 mm)	17.5 ± 15	18 ± 14	18 ± 16	16 ± 13
Periphery (2 mm)	17.7 ± 16	18 ± 13	20 ± 17	16 ± 13
ChT: Quadrant
Superior	16.0 ± 12	19.9 ± 13	16.5 ± 13	11.6 ± 8*
Temporal	20.2 ± 17	22.5 ± 13	22.3 ± 19	15.8 ± 12*^†
Inferior	15.5 ± 12	18.9 ± 15	14.7 ± 12	12.8 ± 8
Nasal	22.5 ± 18	25.1 ± 18	23.1 ± 19	19.2 ± 15

Notes: *Significantly less diurnal variation amplitude in the refractive group compared to the emmetropic group (p < 0.05) with adjustment for multiple comparisons (Bonferroni). ^†Significantly less diurnal variation amplitude in the high myopic refractive group compared to the myopic group (p < 0.05) with adjustment for multiple comparisons (Bonferroni).

Figure 3 Mean change in subfoveal choroidal thickness (ChT) and axial length (AL) among the three refractive groups. Error bars represent standard error of the mean.

Figure 4 Scatter plots graphs illustrating the association between the diurnal variation amplitude in choroidal thickness and refraction (A) and between the variation in axial length and refraction (B).