Binocular Dynamic Visual Acuity in Eyeglass-Corrected Myopic Patients

Summary

The present research demonstrates a method to accurately examine dynamic visual acuity (DVA) in myopic subjects with eyeglass correction. Further analysis indicated that the closer the refraction state to emmetropia, the better the eyeglass-corrected binocular DVA is at both 40 and 80 degrees per second.

Abstract

Current clinical visual assessment mainly focuses on static vision. However, static vision may not sufficiently reflect real-life visual function as moving optotypes are frequently observed daily. Dynamic visual acuity (DVA) might reflect real-life situations better, especially when objects are moving at high speeds. Myopia impacts static uncorrected distance visual acuity, conveniently corrected with eyeglasses. However, due to peripheral defocus and prism effects, eyeglass correction might affect DVA. The present research demonstrates a standard method to examine eyeglass-corrected DVA in myopia patients, and aimed to explore the influence of eyeglass correction on DVA.

Initially, standard subjective refraction was performed to provide the eyeglass prescription to correct the refractive error. Then, binocular distance vision-corrected DVA was examined using the object-moving DVA protocol. Software was designed to display the moving optotypes according to the preset velocity and size on a screen. The optotype was the standard logarithmic visual chart letter E and moves from the middle of the left to the right side horizontally during the test. Moving optotypes with randomized opening direction for each size are displayed. The subjects were required to identify the opening direction of the optotype, and the DVA is defined as the minimum optotype that subjects could recognize, calculated according to the algorithm of logarithmic visual acuity.

Then, the method was applied in 181 young myopic subjects with eyeglass-corrected-to-normal static visual acuity. Dominant eye, cycloplegic subjective refraction (sphere and cylinder), accommodation function (negative and positive relative accommodation, binocular cross-cylinder), and binocular DVA at 40 and 80 degrees per second (dps) were examined. The results showed that with increasing age, DVA first increased and then decreased. When myopia was fully corrected with eyeglasses, a worse binocular DVA was associated with more significant myopic refractive error. There was no correlation between the dominant eye, accommodation function, and binocular DVA.

Introduction

Current visual assessment mainly focuses on static vision, including static visual acuity (SVA), visual field, and contrast sensitivity. In daily life, either the object or the observer is often in motion rather than being stationary. Therefore, SVA may not sufficiently reflect visual function in daily lives, especially when objects are moving at high speeds, such as during sports and driving¹. DVA defines the ability to identify the details of moving optotypes^1,2, which might reflect real-life situations better and be more sensitive to visual disturbance and improvement^3,4. Moreover, as magnocellular (M) ganglion cells located mainly in the peripheral retina primarily transmit high temporal frequency signals, DVA might reflect visual signal transmission differently from SVA^5,6. The DVA test (DVAT) can be mainly divided into two types: static- and moving-object DVATs. While the static-object DVAT demonstrates the vestibule-ocular reflex^7,8,9,10, the moving-object DVAT is commonly applied in clinical ophthalmology to detect visual acuity in the identification of moving targets^3,4.

The prevalence of myopia has rapidly increased in recent decades, especially in Asian countries¹¹. Myopia has an essential impact on static uncorrected distance visual acuity, which could be corrected with various lenses. Eyeglasses are mostly used among myopia patients due to accessibility and convenience. However, eyeglasses, especially high myopia lenses, have obvious peripheral defocus and prism effects that cause unclear and skewed images to be observed through the peripheral region^12,13,14,15. For a static optotype, the subject commonly uses the central area of eyeglasses that could obtain a clear vision. However, the moving target could easily move out of the eyeglasses' clearest point. Thus, with eyeglass correction, myopic subjects might have normal SVA and affected DVA. However, no research has been performed to investigate the impact of myopia diopter on DVA in populations with eyeglasses.

This study demonstrates a method to examine DVA in eyeglass-corrected myopia patients and aimed to explore the impact of myopia diopter on moving-object binocular DVA in eyeglass-corrected patients. The research provides a basis for accurately interpreting DVAT in clinical ophthalmology considering the impact of eyeglasses and evidence on the influence of corrected myopia on motion-related activities.

Protocol

The present study enrolled consecutive myopia patients in the Department of Ophthalmology of Peking University Third Hospital. The research protocol was approved by the Peking University Third Hospital Ethics Committee, and informed consent was obtained from each participant.

1. Patient preparation

1. Use the following initial inclusion criteria to enroll subjects: myopia subjects aged 17-45 years old.
2. Use the following exclusion criteria: any history of ocular diseases, including keratitis, glaucoma, cataract, retinal and macular diseases, that significantly impact corrected distance visual acuity (CDVA). Evaluate uncorrected distance visual acuity (using the standard logarithmic VA chart), dominant eye, intraocular pressure, slit lamp, corneal topography, fundus photography, automatic computer optometry, cycloplegic subjective refraction, and CDVA. Exclude participants with keratoconus, cloudy cornea, or retinal abnormalities, including retinal breaks, retinal vascular inflammation, congenital retinal and macular diseases, or monocular CDVA worse than zero (based on the standard logarithmic VA chart).
3. Set up the DVA test components, including test distance, environment, hardware, software, movement mode, and rules as follows:
   1. For test distance and environment, set the test distance according to the size of the screen and examination requirements.
      ​NOTE: Here, DVA was assessed at 2.5 m in a quiet and bright room (luminance 15-30 lux).
   2. For hardware, present the optotype with a 24 inch in-plane switching (IPS) or twisted nematic (TN) screen (refresh rate, 60 to 144 Hz; response rate less than 5 ms).
   3. Ensure that the software is designed to display the optotype according to the preset velocity and size. Use the dynamic optotype as the letter E designed according to the standard logarithmic visual chart with four opening directions: upper, left, lower, and right. Ensure that the visual angle of the motion optotype presented at the test distance equals the optotype with the decimal size in the standard logarithmic visual chart. Set the color of the letter E to black, with a white background. Express the velocity of motion as the viewing angle changes per second.
   4. Movement mode: during the test, ensure that the optotype with a specific size and velocity appears in the middle of the screen's left side, moves horizontally to the right side, and then disappears.
   5. Test rule: Ask the subjects to identify the opening direction of the visual target. Test the minimum visual target at a certain speed that the subjects can recognize.

2. Subjective refraction

NOTE: The result of subjective cycloplegic refraction is the basis for the eyeglasses prescription to correct the refractive error in myopia subjects.

1. Perform automatic computer optometry as the primary data for subjective cycloplegic refraction and measure the pupil distance.
2. Examine one eye at a time and occlude the other eye.
   1. First, achieve the maximum plus to maximum visual acuity: fogging with +0.75 - +1.0 D lens, inducing a visual acuity of 0.3-0.5 (decimal visual acuity). Next, gradually decrease the positive lens in a 0.25 D step. Use a Lancaster red-green test to tune the accurate spherical diopter. Add more negative/positive lens if the patients report that the letter seen against the red/green background is clearer.
      NOTE: The primary spherical diopter is obtained after the above step.
3. Refine the cylinder axis.
   1. Place the Jackson cross cylinder device in the "axis" position so that the thumb-wheel's connecting line is parallel to the axis of the astigmatism. Rotate the thumb-wheel and ask the subject to compare the clearness between both sides. Turn the cylinder axis toward the red dots on the cross cylinder in the side with clearer vision. Repeat the binary comparison until the endpoint.
4. Refine cylinder power.
   1. Turn the Jackson cross cylinder device so that the thumb-wheel's connecting line is at 45° to the astigmatism axis. Rotating the thumb-wheel, ask the subject to compare the clearness between both sides. If the patient reports clearer placement of the cross cylinder red/white dots connecting line along the cylinder axis, add a negative/positive lens, respectively. Repeat the binary comparison until the endpoint.
5. For the second maximum plus to maximum visual acuity, repeat the Lancaster red-green test to tune the accurate spherical diopter.
6. For binocular balance, apply a vertical prism of 6Δ before one eye to dissociate the binocular vision. Balance the clearness of the optotypes between both eyes.

3. Dynamic visual acuity test

NOTE: DVA was measured binocularly with refractive errors fully corrected with eyeglasses in the present study.

1. Test settings
   1. Adjust the test distance according to the requirements. Adjust the seat to make the subject's sight at the screen's midpoint level. Ensure the subject wears the distance vision corrected eyeglasses binocularly.
2. Test parameter configurations
   1. Set the optotype moving velocity and the initial optotype size.
3. For the pretest, display five optotypes with a randomized opening direction to guide the subjects to understand the test mode.
4. Formal test
   1. Start the test at the size 3-4 lines bigger than the best-corrected distance visual acuity. Display the optotype with randomized opening directions.
   2. Ask the subject to identify the opening direction of the moving optotype. Present the next optotype after the subject's response. Present eight optotypes for a certain size. If five out of eight optotypes are identified correctly, adjust the optotype to one size smaller. Repeat the above procedures until the size for which the subject can identify less than five optotypes is obtained.
5. Record the minimum size (A, decimal VA) that subjects can recognize (five out of eight optotypes are identified correctly) and the number (b) of optotypes recognized for one size smaller than A.
6. DVA calculation
   1. Present eight optotypes for each size so that each identified optotype gains 0.1/8 visual acuity. Calculate DVA according to the algorithm of logarithmic visual acuity, as shown by Eq (1); see step 3.5 for an explanation of A and b:
      (1)
      NOTE: In the present study, optotypes of 40 and 80 dps were examined in order. Previous studies have reported that people could apply smooth pursuit when observing dynamic objects moving at 30-60 dps, whereas observing objects moving faster than 60 dps involves head movement and saccade^16,17. Thus, two motion speeds of 40 and 80 dps were selected.

Representative Results

Subject examinations
For the enrolled subjects, accommodation function, including negative relative accommodation (NRA), accommodation response (binocular cross-cylinder (BCC)), and positive relative accommodation (PRA), were examined in the mentioned order. Binocular DVA at 40 dps and 80 dps was tested with distance visual acuity-corrected eyeglasses based on subjective refraction.

Statistical analysis
Statistical analysis was performed using scientific statistical software. Descriptive statistics of continuous variables were reported as the mean and standard deviation, and numbers and proportions were applied for categorical variables. The binocular difference (OD/OS) was the absolute value of the difference between the right and left eyes, and the binocular difference (D/ND) was calculated as the value of the nondominant eye subtracted from that of the dominant eye.

A paired t-test was used to compare the DVA at 40 dps and 80 dps. Curve estimation, including linear, quadratic, and cubic models, was used to fit the correlation between DVA and age. To analyze the potentially influential factors, linear mixed models were established to fit with DVA as the dependent variable and included the random effect at the subject level. First, single-factor linear mixed models were applied to estimate the effect of each variable as a covariant or factor according to the type of the variable. The following variables were tested as potential influential factors for DVA: refraction parameters, including the monocular and mean binocular sphere; cylinder and spherical equivalent (SE); and the absolute value of the difference in the binocular sphere; cylinder and SE; dominant-eye parameters, including dominant and nondominant-eye sphere; cylinder and SE; and the difference in the sphere, cylinder, and SE between the dominant and nondominant eye and accommodation function parameters, including NRA, BCC, and PRA.

Next, a multifactor linear mixed model was established to include several potential influential factors in one model. For a preparatory step, collinearity analysis was conducted with the included variables. A variance inflation factor greater than 10 was considered to indicate multicollinearity. Redundant variables were excluded based on clinical significance. Based on the influential factors used, two different models were fitted: the full and dominant-eye models. For the full model, the following variables were included: age; sex; accommodation function parameters (NRA, BCC, and PRA); mean binocular SE and the absolute value of the difference in the binocular cylinder and SE, dominant eye, dominant-eye cylinder, and the difference in cylinder and SE between the dominant and nondominant eyes following the preparatory collinearity analysis. For the dominant-eye model, only dominant-eye parameters were included as influential factors. P < 0.05 denotes a significant difference.

The demographic and main clinical data of the included subjects are shown in Table 1. This study included 181 subjects, with an average age of 27.1 ± 6.3 years old, and males accounted for 37.6% of the subjects. The right eye was the dominant eye for 60.2% of subjects. The mean binocular sphere and cylinder were -5.26 ± 2.06 D and -0.99 ± 0.82 D, respectively. The absolute values of the difference in the binocular sphere and cylinder were 0.85 ± 0.91 D and 0.39 ± 0.34 D, respectively.

The cumulative LogMAR visual acuity of DVA at 40 and 80 dps and the histogram are presented in Figure 1. The cumulative results demonstrated that 75% of subjects possessed better than 0.2 LogMAR DVA for 40 dps and 62% for 80 dps DVA. The percentage of the subjects with better than 0.1 logMAR 40 dps binocular DVA was 22%, and for 80 dps, the percentage was 12%. The average binocular DVA values at 40 dps and 80 dps were 0.161 ± 0.072 and 0.189 ± 0.076, respectively, and the 40 dps DVA was significantly better than the 80 dps DVA (P < 0.001).

The results of curve estimation between DVA and age are demonstrated in Figure 2. Significant results were obtained fitting an age-DVA of 40 dps with a quadratic (R² = 0.38, P = 0.031) and cubic curve (R² = 0.38, P = 0.030), but not a linear model (R² = 0.21, P = 0.051). For 80 dps DVA, all the linear (R² = 0.24, P = 0.035), quadratic (R² = 0.43, P = 0.019), and cubic (R² = 0.43, P = 0.020) curves could appropriately fit the age-DVA scatter plot.

Figure 3 demonstrates the effect of each potential influential factor for 40 and 80 dps DVA in single-factor linear mixed models, and the statistical results are summarized in Table 2 and Table 3. Larger right (estimate, -0.012), left (estimate, -0.010), dominant (estimate, -0.010), and nondominant (estimate, -0.010) eye spheres; larger right (estimate, -0.012), left (estimate, -0.010), dominant (estimate, -0.010) and nondominant (estimate, -0.010) eye SEs; and larger mean binocular spheres (estimate, -0.012) and SEs (estimate, -0.012) were significant negative influential factors of 40 dps DVA (P < 0.001 for each variable). For DVA of 80 dps, larger monocular sphere and SE (estimate, -0.012, -0.010, -0.010, -0.010 for right, left, dominant, and nondominant eye, respectively; P < 0.001 for each variable), larger left eye cylinder (estimate, -0.013; P = 0.04), larger nondominant eye cylinder (estimate, -0.016; P = 0.01), smaller binocular cylinder difference between dominant and nondominant eye (estimate, 0.027; P = 0.015), larger mean binocular sphere (estimate, -0.012; P < 0.001) and SE (estimate, -0.012; P < 0.001) were significant negative influential factors. Accommodation function parameters, including NRA, BCC, and PRA, were not significant influential factors for either 40 or 80 dps DVA.

Figure 4 illustrates the effects of factors and covariates for the full variables linear mixed model for 40 and 80 dps DVA, and the results are summarized in Table 4. When 40 dps DVA was used to measure variability, only a larger binocular mean SE (estimate, -0.012; 95% CI, -0.017 to -0.006; P < 0.001) was a significant negative influential factor. Larger mean binocular SE (estimate, -0.011; 95% CI, -0.016 to -0.005; P < 0.001) and older age (estimate, 0.002; 95% CI, 0.00002 to -0.004; P < 0.048) were significant negative influential factors for 80 dps DVA.

Figure 5 shows the effect of factors and covariates for the dominant-eye multifactor linear mixed model, and the results are summarized in Table 5. Variables selected in the dominant-eye model included the dominant eye, dominant eye SE, dominant eye cylinder, binocular cylinder, and SE difference between the dominant and nondominant eyes based on collinearity analysis. When 40 and 80 dps DVA were used to measure variability, only larger dominant-eye SE (estimate, -0.010; 95% CI, -0.015 to -0.005; P < 0.001 for 40 and 80 dps analysis) was a significant negative influential factor.

Figure 1: Dynamic visual acuity distribution. (A) Histogram of DVA at 40 dps; (B) Histogram of DVA at 80 dps; (C) Cumulative percentage of DVA at 40 and 80 dps H. Abbreviations: DVA = dynamic visual acuity; dps = degrees per second. Please click here to view a larger version of this figure.

Figure 2: Scatter plots and fitting curves showing the curve estimation between age and DVA. (A) Linear model for 40 dps DVA; (B) Quadratic model for 40 dps DVA; (C) Cubic model for 40 dps DVA; (D) Linear model for 80 dps DVA; (E) Quadratic model for 80 dps DVA; (F) Cubic model for 80 dps DVA. Abbreviations: DVA = dynamic visual acuity; dps = degrees per second. Please click here to view a larger version of this figure.

Figure 3: Forest plot showing the single-factor model. The central short stick indicates the estimates; bars indicate the 95% confidence interval. *The binocular difference (OD/OS) was the absolute value of the difference between the right and left eyes. #The binocular difference (D/ND) was calculated subtracting the nondominant eye value from the dominant eye value. Abbreviations: BCC = binocular cross-cylinder; NRA = negative relative accommodation; PRA = positive relative accommodation; SE = spherical equivalent. Please click here to view a larger version of this figure.

Figure 4: Forest plot showing the full model. The central short stick indicates the estimates; bars indicate the 95% confidence interval. *The binocular difference (OD/OS) was the absolute value of the difference between the right and left eyes. #The binocular difference (D/ND) was calculated subtracting the nondominant eye value from the dominant eye value. Abbreviations: BCC = binocular cross-cylinder; NRA = negative relative accommodation; PRA = positive relative accommodation; SE = spherical equivalent. Please click here to view a larger version of this figure.

Figure 5: Forest plot showing the dominant-eye model. The central short stick indicates the estimates; bars indicate the 95% confidence interval. *The binocular difference (OD/OS) was the absolute value of the difference between the right and left eyes. #The binocular difference (D/ND) was calculated subtracting the nondominant eye value from the dominant eye value. Abbreviations: BCC = binocular cross-cylinder; NRA = negative relative accommodation; PRA = positive relative accommodation; SE = spherical equivalent. Please click here to view a larger version of this figure.

Table 1: Demographic and main clinical data of the study population. The demographic data, refraction parameters, dominant eye parameters, and accommodation function of the study population are shown. *The binocular difference (OD/OS) was the absolute value of the difference between the right and left eyes. #The binocular difference (D/ND) was calculated subtracting the nondominant eye value from the dominant eye value. Abbreviations: DVA = dynamic visual acuity; dps = degrees per second; BCC = binocular cross-cylinder; NRA = negative relative accommodation; PRA = positive relative accommodation; SE = spherical equivalent. Please click here to download this Table.

Table 2: Results of single-factor linear mixed model for 40 dps DVA variability. The statistical results of a linear mixed model are demonstrated with DVA of 40 dps as the dependent variable. The refraction, dominant eye, and accommodation function parameters serve as independent variables. *The binocular difference (OD/OS) was the absolute value of the difference between the right and left eyes. #The binocular difference (D/ND) was calculated subtracting the nondominant eye value from the dominant eye value. Abbreviations: DVA = dynamic visual acuity; dps = degrees per second; BCC = binocular cross-cylinder; NRA = negative relative accommodation; PRA = positive relative accommodation; SE = spherical equivalent. Please click here to download this Table.

Table 3: Results of single-factor linear mixed model for 80 dps DVA variability. The statistical results of a linear mixed model are demonstrated with DVA of 80 dps as the dependent variable. The refraction, dominant eye, and accommodation function parameters serve as independent variables. *The binocular difference (OD/OS) was the absolute value of the difference between the right and left eyes. #The binocular difference (D/ND) was calculated subtracting the nondominant eye value from the dominant eye value. Abbreviations: DVA = dynamic visual acuity; dps = degrees per second; BCC = binocular cross-cylinder; NRA = negative relative accommodation; PRA = positive relative accommodation; SE = spherical equivalent. Please click here to download this Table.

Table 4: Results of full model for 40 and 80 dps DVA variability. The statistical results of a multifactor linear mixed model are demonstrated with DVA of 40 or 80 dps as the dependent variable. The variables include age, sex, accommodation function parameters, mean SE, and the absolute value of the difference in the binocular cylinder and SE, dominant eye, dominant-eye cylinder, and the difference in cylinder and SE between the dominant and nondominant eyes following the preparatory collinearity analysis. *The binocular difference (OD/OS) was the absolute value of the difference between the right and left eyes. #The binocular difference (D/ND) was calculated subtracting the nondominant eye value from the dominant eye value. Abbreviations: DVA = dynamic visual acuity; dps = degrees per second; BCC = binocular cross-cylinder; NRA = negative relative accommodation; PRA = positive relative accommodation; SE = spherical equivalent. Please click here to download this Table.

Table 5: Results of dominant-eye model for 40 and 80 dps DVA variability. The statistical results of a linear mixed model are demonstrated with DVA of 40 or 80 dps as the dependent variable. The variables include dominant eye parameters. #The binocular difference (D/ND) was calculated subtracting the nondominant eye value from the dominant eye value. Abbreviations: DVA = dynamic visual acuity; dps = degrees per second; CI = confidence interval; DVA = dynamic visual acuity; SE = spherical equivalent. Please click here to download this Table.

Discussion

DVA is a promising indicator to assess visual function, which might better reflect actual vision in daily life. Myopic patients could have corrected, normal SVA, but their DVA might be affected. This study demonstrates a method to examine the DVA in myopic subjects with eyeglass correction accurately and analyzes its correlation with optometric parameters, including refraction, accommodation, and the dominant eye. The results indicated that DVA at 40 dps was superior to that at 80 dps. The closer the refraction state is to emmetropia, the better the eyeglass-corrected DVA at 40 and 80 dps. No correlation was found between DVA and accommodation function parameters and the dominant eye.

In the present study, the SVA was corrected completely with eyeglasses for all subjects. However, the DVA value differs from person to person. The single-factor linear mixed model results indicated that monocular and binocular mean sphere and SE are all significant influential factors for DVA, which means that the closer the refractive state is to emmetropia, the better the DVA at 40 and 80 dps. The results suggested that the decrease in DVA caused by ametropia may be challenging to completely correct with eyeglasses. Several mechanisms might be able to explain the results. The prism effect is stronger in larger diopter eyeglasses, which has a displacement effect on the object image¹⁸. Robust DVA depends on an accurate prediction of the target's motion trajectory to form an effective pursuit and saccade^16,17. Thus, the prism effect may affect the subjects' prediction of the movement of dynamic visual targets and affect the pursuit, resulting in worse DVA¹⁸. Previous research demonstrates no significant difference in DVA among tennis athletes with normal vision or refractive errors with and without correction¹⁹. The difference in the results might be attributed to the difference in the test distance. The DVA test in that study was performed at a near distance (45 cm), and the near visual acuity might not have been affected in subjects with refractive error.

Future studies could further apply eye-tracking tools during DVAT to record ocular movements to substantiate this assumption. Moreover, the visual clarity in the peripheral region of eyeglasses is less clear than that in the central region due to peripheral defocus¹². While observing moving targets, objects could not image constantly through the central zone²⁰. Thus, unclear vision through the paracentral or peripheral visual field could impact DVA. Moreover, previous research has demonstrated that myopic eyes have a thinner GC-IPL and retinal nerve fiber layer (RNFL) than emmetropic eyes^21,22. RNFL thickness and ganglion cell density decrease with increasing myopia diopter²². The decrease in ganglion cell density in myopic eyes may decrease the function of visual signal transmission and management, leading to a decrease in DVA conduction function.

The present study found that the diopter of eyeglasses influenced DVA with SVA correction, and the larger the diopter was, the worse the DVA. A previous study has shown that people wearing eyeglasses tend to experience a higher risk of traffic accidents²³, which may be related to the impact of peripheral vision damage of eyeglasses on DVA. Thus, DVAT might better reflect functional vision in daily life to provide information for driving safety and sports performance. Since the diopter of eyeglasses significantly impacts the DVA, highly myopic subjects who have a higher demand for dynamic vision might choose to correct the refractive error with methods other than eyeglasses or have substantial career planning. In the future, the influence of other myopia correction methods on DVA, including contact lenses and refractive surgeries, can be further explored for occupational-based recommendations, including drivers and athletes. Moreover, considering the impact of age and refractive error correction on DVA, different ranges of normal values should be set according to age, and the impact of refractive error diopter should be considered when applying DVAT in the clinical setting.

Certain limitations exist in the present study. First, this study only investigated the impact of myopia on DVA in eyeglass-corrected patients. Other static distance visual acuity correction methods, including contact lenses and surgeries, might also influence DVA, which should be further investigated in the future. Second, only a single mode of optotype movement was applied in the test. More movement directions need to be explored in the future. A DVAT that can change the observation depth of the field can be designed to better reflect real-life scenes such as driving. Third, DVA is associated with eye tracking, including smooth pursuit and saccade. The present research lacks accessibility to eye-tracking devices, which is helpful for these kinds of studies. Further research could collect eye-tracking data during DVAT to substantiate ocular movement during the test. Fourth, compared with parvocellular (P) ganglion cells, magnocellular (M) ganglion cells primarily transmit high temporal frequency signals, which might be responsible for the visualization of the motion optotype in the test, which remains to be explored in future research.

In summary, the study evaluated and analyzed optometric influential factors in binocular DVA in myopic subjects whose vision was corrected to normal with eyeglasses. The results provided the normal values and distributions of DVA at 40 and 80 dps, and demonstrated that the binocular DVA at 40 dps was significantly superior to that at 80 dps. DVA improves first and then declines with aging. With SVA corrected with eyeglasses, the worse the monocular and binocular sphere and SE, the worse the DVA. No correlation was found between the dominant eye, accommodation function and DVA. The present research provides a standard and efficient protocol to examine DVA in eyeglass-corrected myopia patients, and provides the basis for better interpreting DVAT in clinical ophthalmology and evidence on the impact of eyeglass correction on motion-related activities.

Materials

Name	Company	Catalog Number	Comments
Automatic computer optometry	TOPCON	KR8100
Corneal topography	OCULUS	Pentacam
Dynamic visual acuity test design software	Mathworks	matlab 2017b
Fundus photography	Optos	Daytona
Matlab	Mathworks	2017b
Noncontact tonometry	CANON	TX-20
Phoropter	NIDEK	RT-5100
scientific statistical software	IBM	SPSS 26.0
Slit lamp	Koniz	IM 900