Atropine Affects the Outer Retina During Inhibiting Form Deprivation Myopia in Guinea Pigs

Figures & data

Table 1. Data of refraction and ocular biometrics in the two groups (mean ± SEM)

Parameter, Eye	Group	Baseline	Week 2		Change	FDM against fellow	FDM against FDM
RE (D)
FDM	Saline	2.16 ± 0.16	−0.41 ± 0.55		−2.58 ± 0.54	P = .003
Fellow	Saline	2.32 ± 0.18	2.42 ± 0.24		0.10 ± 0.27
FDM	Atropine	2.71 ± 0.26	1.72 ± 0.46		−1.00 ± 0.37	P = .10	P = .03
Fellow	Atropine	2.74 ± 0.18	2.43 ± 0.22		−0.31 ± 0.24
VCD (mm)
FDM	Saline	3.09 ± 0.02	3.28 ± 0.04		0.20 ± 0.04	P < .001
Fellow	Saline	3.08 ± 0.02	3.10 ± 0.03		0.02 ± 0.02
FDM	Atropine	3.04 ± 0.02	3.07 ± 0.03		0.03 ± 0.02	P = .92	P = .001
Fellow	Atropine	3.04 ± 0.02	3.07 ± 0.01		0.03 ± 0.02
AL (mm)
FDM	Saline	7.80 ± 0.04	8.22 ± 0.07		0.42 ± 0.06	P = .001
Fellow	Saline	7.80 ± 0.05	7.98 ± 0.05		0.18 ± 0.04
FDM	Atropine	7.67 ± 0.05	7.93 ± 0.06		0.26 ± 0.02	P = .02	P = .03
Fellow	Atropine	7.67 ± 0.05	8.02 ± 0.07		0.36 ± 0.06

Statistics denote difference of change over the treatment period (week 2–baseline). FDM against fellow implies the comparison between the treated and the control eyes in one group (paired t-test). FDM against FDM implies the comparison between the treated eyes in two groups (two-way ANOVA with a Bonferroni post hoc test). RE: refractive error, VCD: vitreous chamber depth, AL: axial length.

Figure 1. Interocular differences in RE (a), VCD (b), and AL (c) Before and after form-deprivation treatment in the saline and the atropine groups (mean ± SEM, experimental – fellow). The myopic progression in FDM eyes was significantly retarded in the atropine group. Interocular differences after the treatment were plotted, showing a significant linear correlation between RE and VCD (d), and between RE and AL (e). (a–c) Two-way mixed ANOVA with a Bonferroni post hoc test: **: P < .01; ***: P < .001; ****: P < .0001; D -E: linear regression analysis, n = 10. RE: refractive error, VCD: vitreous chamber depth, AL: axial length

Table 2. Data of retinal and choroidal thickness in the two groups (mean ± SEM)

Parameter, Eye	Group	Baseline	Week 2	Change	FDM against fellow	FDM against FDM
RT (µm)
FDM	Saline	138.12 ± 1.46	131.58 ± 1.47	−6.54 ± 2.46	P = .87
Fellow	Saline	137.66 ± 1.37	131.68 ± 1.56	−5.98 ± 1.50
FDM	Atropine	134.95 ± 2.60	141.42 ± 2.47	6.47 ± 4.09	P = .007	P = .02
Fellow	Atropine	135.19 ± 2.60	131.54 ± 2.11	−3.64 ± 3.52
ORT (µm)
FDM	Saline	59.79 ± 1.97	54.52 ± 1.14	−5.27 ± 2.62	P = .97
Fellow	Saline	59.51 ± 1.67	54.31 ± 1.15	−5.20 ± 2.21
FDM	Atropine	56.69 ± 1.81	61.74 ± 2.06	5.05 ± 2.87	P = .008	P = .02
Fellow	Atropine	55.28 ± 1.83	53.86 ± 1.53	−1.42 ± 1.93
IRT (µm)
FDM	Saline	78.33 ± 1.60	77.06 ± 1.11	−1.27 ± 2.27	P = .83
Fellow	Saline	78.15 ± 1.59	77.37 ± 0.76	−0.79 ± 1.85
FDM	Atropine	78.27 ± 1.36	79.69 ± 1.33	1.42 ± 2.11	P = .12	P = .40
Fellow	Atropine	79.91 ± 1.40	77.68 ± 1.48	−2.22 ± 2.10
ChT (µm)
FDM	Saline	119.12 ± 5.69	94.50 ± 9.45	−24.62 ± 11.27	P = .06
Fellow	Saline	113.22 ± 5.13	115.49 ± 7.81	2.27 ± 5.97
FDM	Atropine	113.14 ± 5.96	111.65 ± 6.88	−1.48 ± 9.80	P = .73	P = .15
Fellow	Atropine	110.83 ± 4.99	113.56 ± 10.31	2.73 ± 13.93

Statistics denote difference of change over the treatment period (week 2–baseline). FDM against fellow implies the comparison between the treated and the control eyes in one group (paired t-test). FDM against FDM implies the comparison between the treated eyes in two groups (two-way ANOVA with a Bonferroni post hoc test). RT: retinal thickness; ORT: outer retinal thickness; IRT: inner retinal thickness; ChT: choroidal thickness.

Figure 2. Interocular differences in retinal thickness (a) Outer retinal thickness, ORT, (b) Inner retinal thickness, IRT (c), and choroidal thickness, ChT (d) before and after treatment in the saline and atropine groups (mean ± SEM, experimental – fellow). The retinal thickness (a) and the outer retinal thickness (b) were increased with the treatment of atropine, while they were unaffected in the saline group. The inner retinal thickness showed no difference between the two groups (c). There was a decreasing trend for ChT in the saline-treated FDM eyes, yet the trend was diminished by atropine treatment (d). Two-way mixed ANOVA with a Bonferroni post hoc test: **: P < .01; ***: P < .001, n = 7

Figure 3. ERG wave of a representative guinea pig from the saline group (left) and the atropine group (right). The black curve indicates the FDM eye, while the red curve indicates the control eye

Figure 4. a-Wave amplitudes in the photopic (a), scotopic (c) adapted ERG. The comparison of the FDM eyes between two groups in the photopic (b), scotopic (d) adapted ERG (mean ± SEM). In the photopic ERG (a), the saline-treated FDM eyes show a declining trend in a-wave amplitudes compared to the control eyes. The differences were not statistically significant. The amplitudes in the atropine-treated FDM eyes were higher than the control eyes under the stimulation of 1 and 3 cd·s/m² (A, paired t-test). The a-wave amplitudes increased significantly in the atropine-treated FDM eyes compared to the saline group under the stimulation of 10 and 30 cd·s/m² (a and b, two-way repeated measures ANOVA with Bonferroni post hoc test). In the scotopic ERG, the a-wave amplitudes of atropine-treated FDM eyes tended to be higher than those of the saline-treated FDM eyes under higher stimulus intensity, but the differences were not significant (c,d): *: P < .05, **: P < .01, n = 8