Analysis of the Outcomes of the Screen-Time Reduction in Computer Vision Syndrome: A Cohort Comparative Study

Figures & data

Table 1 Comparison Between the A and B Groups Before Screen-Time Reduction

Parameters	Group A (Mean ± SD) Median (Range)	Group B (Mean ± SD) Median (Range)	Mean Difference (Group B-Group A) (95% Confidence of Interval)	P value
Age	21.56±1.16	21.36±1.22	−0.2 (−0.88:0.48)	0.56
	21 (19:23)	21 (19:23)
Sex (no. / %)
Male	12 (48.00%)	11 (44.00%)		0.78
Female	13 (52.00%)	14 (56.00%)
Daily screen-hours (hours):	2.32±1.22	5.48±1.92	3.16 (2.25:4.07)	<0.0001
	2 (1:5)	5 (3:9)
Visual outcomes (logMAR):
UDVA	0.12±0.19	0.36±0.25	0.24 (0.11:0.36)	0.0006
	0.1 (−0.2:0.6)	0.3 (0:0.9)
CDVA	−0.08±0.09	0.02±0.08	0.1 (0.05:0.15)	0.0002
	−0.1 (−0.3:0)	0 (−0.1:0.2)
mfERG first examination outcomes: I- Amplitudes P1: (normal range nV/deg^2)
Ring 1	86.40±15.53	54.00±10.86	−32.40 (−40.02:-24.78)	<0.0001
R1 (66.6–130.8)	85.32 (62.07:141.4)	49.75 (41.72:89.14)
Ring 2	37.43±5.96	30.99±5.02	−6.44 (−9.57:-3.30)	0.0001
R2 (30.9–77.8)	35.75 (26.63:55.45)	31.8 (20.15:38.69)
Ring 3	22.19±3.96	20.22±3.45	−1.97 (−4.08:0.15)	0.07
R3 (21.7–59)	22.35 (13.38:29.76)	20.32 (13.48:28.63)
Ring 4	13.60±2.61	12.11±2.60	−1.50 (−2.98:-0.02)	0.048
R4 (12.9–37.1)	13.63 (8.95:18.92)	11.85 (5.1:17.83)
Ring 5	10.97±2.32	8.63±1.92	−2.34 (−3.56:-1.13)	0.0003
R5 (10–28.2)	10.75 (7.02:15.47)	8.18 (4.32:12.62)
II- Amplitudes P1: (normal range nV/deg^2)
Quadrant 1	12.70±2.97	10.10±2.26	−2.60 (−4.10:-1.10)	0.001
Q1 (15.8–42.74)	12.09 (7.48:19.01)	10.1 (5.05:14.16)
Quadrant 2	15.68±2.44	13.31±2.70	−2.36 (−3.82:-0.90)	0.002
Q2 (15.98–42.75)	16.22 (10.17:18.71)	13.21 (6.44:20.18)
Quadrant 3	16.22±2.77	14.40±3.17	−1.82 (−3.51:-0.13)	0.05
Q3 (15.18–42.05)	15.42 (12.66:21.13)	13.85 (4.89:19.43)
Quadrant 4	11.82±2.50	9.79±2.50	−2.04 (−3.46:-0.61)	0.006
Q4 (13.87–39.61)	11.35 (7.97:16.65)	10.59 (3.26:13.45)

Abbreviations: UDVA, uncorrected visual acuity; CDVA, uncorrected visual acuity; logMAR, logarithm of minimal angle of resolution; Amplitudes P1, amplitude density of the first foveal peak; deg, degree; nV, nanovolts; R1 to R5, Ring 1 to Ring 5; Q1 to Q4, Quadrant 1 to Quadrant 4; SD, standard deviation.

Table 2 Comparison Between the A and B Groups After Screen-Time Reduction

Parameters	Group A (Mean ± SD) Median (Range)	Group B (Mean ± SD) Median (Range)	Mean Difference (Group B-Group A) (95% Confidence of Interval)	P value
Daily screen-hours (hours):	1±0	1±0	0
	1 (1:1)	1 (1:1)
Visual outcomes (logMAR):
UDVA	0.12±0.19	0.23±0.22	0.11 (−0.01:0.23)	0.06
	0.1 (−0.2:0.6)	0.2 (−0.2:0.7)
CDVA	−0.08±0.09	−0.04±0.06	0.04 (−0.006:0.08)	0.09
	−0.1 (−0.3:0)	0 (−0.2:0)
mfERG second examination outcomes: I- Amplitudes P1: (normal range nV/deg^2)
Ring 1	88.14±15.46	70.50±12.30	−17.64 (−25.59:-9.70)	<0.0001
R1 (66.6–130.8)	88.37 (63.12:138.75)	67.37 (45.43:100.1)
Ring 2	38.97±5.89	37.92±7.16	−1.05 (−4.78:2.68)	0.57
R2 (30.9–77.8)	36.68 (31.78:57.86)	36.45 (27.36:52.96)
Ring 3	22.98±3.04	24.18±4.46	1.19 (−0.98:3.36)	0.25
R3 (21.7–59)	22.46 (16.68:30.28)	23.69 (16.33:33.4)
Ring 4	13.78±2.29	12.28±2.36	−1.50 (−2.82:-0.18)	0.03
R4 (12.9–37.1)	13.33 (10.46:18.52)	12.22 (8.34:19.03)
Ring 5	11.84±2.31	9.21±2.05	−2.34 (−3.58:-1.10)	0.0004
R5 (10–28.2)	10.88 (8.35:18.97)	8.68 (6.7:14.95)
II- Amplitudes P1: (normal range nV/deg2)
Quadrant 1	13.00±2.25	12.46±3.17	−0.54 (−2.10:1.01)	0.49
Q1 (15.8–42.74)	12.57 (9.35:18.26)	11.89 (5.67:21.79)
Quadrant 2	16.69±2.01	13.72±2.79	−2.96 (−4.35:-1.59)	0.0001
Q2 (15.98–42.75)	16.89 (12.46:20.46)	13.67 (8.56:19.41)
Quadrant 3	16.66±3.17	15.69±3.57	−0.97 (−2.89:0.95)	0.31
Q3 (15.18–42.05)	15.56 (12.68:23.47)	15.34 (8.45:22.41)
Quadrant 4	12.29±2.00	10.16±2.52	−2.14 (−3.43:0.84)	0.002
Q4 (13.87–39.61)	11.89 (9:15.86)	9.87 (6.36:14.62)

Abbreviations: UDVA, uncorrected visual acuity; CDVA, uncorrected visual acuity; logMAR, logarithm of minimal angle of resolution; Amplitudes P1, amplitude density of the first foveal peak; deg, degree; nV, nanovolts; R1 to R5, Ring 1 to Ring 5; Q1 to Q4, Quadrant 1 to Quadrant 4; SD, standard deviation.

Table 3 Comparison of Outcomes in Group B Before and After Screen-Time Reduction

Parameters	Before (Mean ± SD) Median (Range)	After (Mean ± SD) Median (Range)	Mean Difference (After-Before) (95% Confidence of Interval)	P value
Daily screen-hours (hours):	5.48±1.92	1±0	−4.48 (−5.27:-3.69)	<0.0001
	5 (3:9)	1 (1:1)
Visual outcomes (logMAR):
UDVA	0.36±0.25	0.23±0.22	−0.12 (−0.15:-0.10)	<0.0001
	0.3 (0:0.9)	0.2 (−0.2:0.7)
CDVA	0.02±0.08	−0.04±0.06	−0.06 (−0.10:-0.03)	0.002
	0 (−0.1:0.2)	0 (−0.2:0)
mfERG examination outcomes: I- Amplitudes P1: (normal range nV/deg^2)
Ring 1	54.00±10.86	70.50±12.30	16.50 (12.38:20.61)	<0.0001
R1 (66.6–130.8)	49.75 (41.72:89.14)	67.37 (45.43:100.1)
Ring 2	30.99±5.02	37.92±7.16	6.93 (4.69:9.17)	<0.0001
R2 (30.9–77.8)	31.8 (20.15:38.69)	36.45 (27.36:52.96)
Ring 3	20.22±3.45	24.18±4.46	3.96 (1.94:5.98)	0.0005
R3 (21.7–59)	20.32 (13.48:28.63)	23.69 (16.33:33.4)
Ring 4	12.11±2.60	12.28±2.36	0.17 (−0.49:0.83)	0.59
R4 (12.9–37.1)	11.85 (5.1:17.83)	12.22 (8.34:19.03)
Ring 5	8.63±1.92	9.21±2.05	0.57 (0.11:1.04)	0.02
R5 (10–28.2)	8.18 (4.32:12.62)	8.68 (6.7:14.95)
II- Amplitudes P1: (normal range nV/deg2)
Quadrant 1	10.10±2.26	12.46±3.17	2.36 (1.43:3.30)	<0.0001
Q1 (15.8–42.74)	10.1 (5.05:14.16)	11.89 (5.67:21.79)
Quadrant 2	13.31±2.70	13.72±2.79	0.41 (−0.33:1.16)	0.27
Q2 (15.98–42.75)	13.21 (6.44:20.18)	13.67 (8.56:19.41)
Quadrant 3	14.40±3.17	15.69±3.57	1.29 (0.01:2.57)	0.04
Q3 (15.18–42.05)	13.85 (4.89:19.43)	15.34 (8.45:22.41)
Quadrant 4	9.79±2.50	10.16±2.52	0.37 (−0.07:0.81)	0.10
Q4 (13.87–39.61)	10.59 (3.26:13.45)	9.87 (6.36:14.62)

Abbreviations: UDVA, uncorrected visual acuity; CDVA, uncorrected visual acuity; logMAR, logarithm of minimal angle of resolution; Amplitudes P1, amplitude density of the first foveal peak; deg, degree; nV, nanovolts; R1 to R5, Ring 1 to Ring 5; Q1 to Q4, Quadrant 1 to Quadrant 4; SD, standard deviation.

Figure 1 Comparative visual and mfERG mean outcomes between A and B groups before and four weeks after screen-hour reduction; (A) uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) expressed as logarithm of minimal angle of resolution (logMAR). (B) mfERG 5 Rings (R1, R2, R3, R4 and R5) expressed as nanovolts/ degree² (nV/deg2). (C) mfERG 4 Quadrants (Q1, Q2, Q3, and Q4) expressed as nanovolts/ degree2 (nV/deg2).

Note: Before and after means before and after screen-time reduction.

Figure 2 Multifocal electroretinography showing improved foveal responses in the CVS group. (A and B) Oculus sinister of one student before and four weeks after reduction in screen-hours.