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https://doi.org/10.1167/tvst.7.4.9
Article
Impairments of Visual Function and Ocular Structure in
Patients With Unilateral Posterior Lens Opacity
Duoru Lin
1,
*, Jingjing Chen
1,
*, Zhenzhen Liu
1,
*, Zhuoling Lin
1
, Xiaoyan Li
1
, Xiaohang
Wu
1
, Qianzhong Cao
1
, Haotian Lin
1
, Weirong Chen
1
, and Yizhi Liu
1
1
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, 510060,
People’s Republic of China
Correspondence: Haotian Lin, PhD,
Zhongshan Ophthalmic Center, Xian
Lie South Rd #54, Guangzhou,
China, 510060. e-mail: gddlht@
aliyun.com
Weirong Chen, MD, Zhongshan
Ophthalmic Center, Xian Lie South
Rd #54, Guangzhou, China, 510060.
e-mail: chenwr_q@aliyun.com
Received: 3 January 2018
Accepted: 6 June 2018
Published: 24 July 2018
Keywords: congenital cataract;
posterior cataract; visual function;
visual evoked potential; visual im-
pairment
Citation: Lin D, Chen J, Liu Z, Lin Z,
Li X, Wu X, Cao Q, Lin H, Chen W, Liu
Y. Impairments of visual function
and ocular structure in patients with
unilateral posterior lens opacity
Trans Vis Sci Tech. 2018;7(4):9,
https://doi.org/10.1167/tvst.7.4.9
Copyright 2018 The Authors
Purpose: We investigate visual function impairment and ocular structure in patients
with unilateral posterior lens opacity, a type of congenital cataract (CC) in our novel
CC category system.
Methods: We studied patients aged 3 to 15 years who were diagnosed with unilateral
posterior CC. Best corrected visual acuity (BCVA) and visual evoked potentials (VEP)
were examined. Corneal astigmatism (CA), mean keratometry, central corneal
thickness, anterior chamber depth (ACD), and axial length were measured by
Pentacam and IOL-Master. Variations between two eyes were compared by paired t-
tests.
Results: Among the 25 patients involved, BCVAs (logMAR) of cataractous and
contralateral healthy eyes were 0.8 60.4 (range, 0.1–1.7) and 0.1 60.1 (range,
0.1 to 0.4). Compared to contralateral healthy eyes, larger CA (1.8 61.2 vs. 0.9 60.4
diopters [D], P¼0.002) and deeper ACD (3.7 60.3 vs. 3.5 60.4 mm, P¼0.009) were
found in cataractous eyes. No significant positive or negative linear relationship was
found between BCVA and parameters of VEP. Peak time of P100 of pattern VEP-600in
cataractous eyes was longer than that in contralateral healthy eyes (114.9 618.8 vs.
105.0 612.4 ms, P¼0.013). Amplitudes of P100 of patterns VEP-600and -150in
cataractous eyes were smaller than those in contralateral healthy eyes (PVEP-600, 15.2
65.3 vs. 19.9 610.4 lV, P¼0.023; PVEP-150, 10.4 67.0 vs. 22.1 611.9 lV, P¼
0.012).
Conclusions: Impaired visual function and ocular structure were detected in patients
with posterior lens opacities.
Translational Relevance: This study provides evidence-based clinical recommenda-
tions for unilateral posterior CC patients with controversial treatment options.
Introduction
Congenital cataracts (CC) have remained a leading
cause of treatable childhood blindness, with a
worldwide prevalence of 4.24/10000.
1
Due to the
complex etiology with polygenic involvement, pa-
tients with CC exhibit a wide range of clinical lens
opacity presentations.
2
We recently proposed a novel
CC category system (total, anterior, interior, and
posterior cataracts) based on the position of lens
opacities and their anterior segment characteristics,
with the aim to facilitate diagnosis and treatment of
CC.
3
Our findings suggested that genetic and other
nongenetic factors that caused CC also may affect the
cornea, iris, and other anterior segment tissues.
4
Patient treatment plans should vary according to the
specific CC categories to achieve a better treatment
effect. Greater corneal astigmatisms in anterior
cataract and potential shallow anterior chambers in
total cataract patients require appropriate manage-
ment during the treatment process. Undoubtedly,
surgical procedures should be performed as early as
possible after diagnosis of dense total cataracts,
5,6
However, the best timing of surgery for unilateral
posterior cataracts, with seemingly mild opacities, but
an unknown extent of visual impairments, remains
1TVST j2018 jVol. 7 jNo. 4 jArticle 9
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
unclear. Presently, the most commonly used visual
functional impairment assessment method for pa-
tients with CC is subjective visual acuity measure-
ment, which is severely affected by lens opacities and
cannot truly represent the functional integrity of the
retina, visual pathway, and visual cortex of patients
with CC. Visual evoked potentials (VEP) have been
reported previously as a useful objective method to
assess visual function with minimal influences of lens
opacity.
7,8
Combining VEP technique and three-
dimensional (3D) imaging in our study, we compre-
hensively analyzed the alterations of visual function
and ocular structure in patients with unilateral
posterior CC to further explore the clinical treatment
guidance provided by our novel CC category system.
Materials and Methods
Subjects and Ethical Statements
This study was included in our series of ongoing
studies for the Childhood Cataract Program of the
Chinese Ministry of Health (CCPMOH),
9
a national
project for CC treatment and research supported by
the Zhongshan Ophthalmic Center (ZOC). Patients
with CC aged 3 to 15 years who sought treatment at
the ZOC from May 2015 to August 2016 were
included in the current study. All participants were
diagnosed with unilateral CC, which was classified as
posterior cataractous based on slit-lamp and 3D
ocular examinations (Fig. 1). Lens opacities that
involved the posterior capsules were defined as
posterior cataracts, and a more detailed description
of our novel CC category system has been reported
previously.
3
Patients with complications due to other
ocular abnormalities, such as nanophthalmos, glau-
coma, severe corneal diseases, lens luxation, retinal
diseases, strabismus, and nystagmus, were excluded.
This study was approved by the Human Research
Ethics Committee of the ZOC, Sun Yat-sen Univer-
sity. All procedures adhered to the tenets of the
Declaration of Helsinki, and written informed con-
sent was obtained from the legal guardian of each
patient after a detailed explanation of the nature and
possible consequences of the study.
Basic Patient Information and Measurements
of Ocular Structure
The basic information of all patients was collected,
including age, sex, and eye laterality. Best corrected
visual acuity (BCVA) was determined by subjective
refraction with E optotype on a projector. Intraocular
pressure (IOP) was measured by a noncontact
tonometer (TX-F; Canon, Tokyo, Japan) and the
normal range was set from 10 to 21 mmHg.
10
Anterior segment biological parameters were mea-
sured in an undilated pupil before surgical treatment,
including corneal astigmatism (CA), mean keratom-
etry (km), central corneal thickness (CCT), and
anterior chamber depth (ACD). The definitions of
the anterior segment parameters also were described
in detail previously.
11
Measurements were obtained
with a 3D anterior segment imaging and analysis
system (Pentacam HR; Oculus, Inc., Wetzlar, Ger-
many), which is a commercially available camera
based on the Scheimpflug principle. Furthermore,
axial length (AL) also was measured using an IOL-
Master (Carl Zeiss Meditec AG, Jena, Germany). All
ocular biological structure parameters were measured
by two experienced examiners (ZLL and XYL), and
the mean of three measurements that met the quality
standards was calculated for each parameter.
VEP Examinations
The VEP of patients with CC were examined in a
darkroom with MonPackONE (Metrovision, Peren-
chies, France) by two experienced ophthalmologists
(DRL and JJC). Before VEP examination, patients
with undilated pupils were required to spend at least
10 minutes staying in the darkroom with a light-proof
eye mask while seated. After adaptations, the eye
without cataract was first examined to ensure the
patient was familiar with the examination process,
followed by the cataractous eye. The untested eye was
Figure 1. Diagrams of posterior cataracts, one type of our novel
congenital cataract category system.
2TVST j2018 jVol. 7 jNo. 4 jArticle 9
Lin et al.
covered by the light-proof eye mask throughout the
examination. Flash VEP (FVEP) examination was
performed for patients with a BCVA ,1.0 (log-
MAR). FVEP, pattern-reversal VEP-600(PVEP-600),
and PVEP-150were performed for patients with a
BCVA 1.0 (LogMAR). Refractive error was
corrected by an optical lens before PVEP examina-
tions.
12
Electrode cupules (Ag/Agcl) were used and
placed on the head before flash or pattern stimula-
tions. Electrode placement was set strictly according
to the ‘‘10-20 International System,’’ which is based
on measurements of head size.
13
The active electrode
was placed at point Oz along the midline of scalp. The
reference electrode was located at point Fz, while one
earlobe served as the ground location. The VEP
parameters were set as follows: test distance, 0.30 m
for FVEP and 1.0 m for PVEP; stimulation intensity
of FVEP, 3.0 cd.s./m
2
; flashing time, 5.0 ms;
stimulation interval, 1.0 s for PVEP and FVEP;
luminance of the screen for PVEP, 100 cd/m
2
(stimulation on); 5.49 cd/m
2
(stimulation off); 53.7
cd/m
2
(mean); contrast of the black-and-white check-
erboard, 100%; valid responses, 60 times for PVEP
and FVEP; Reliability (a proprietary index provided
by the instrument), .95%; parameters of filters, 1.0
Hz for high pass filter; and 100 Hz for low pass filter.
Two near infrared video cameras equipped in
MonPackONE were used for monitoring fixation:
one near test camera for FVEP tests performed at
0.30 m and one distance test camera for PVEP tests
performed at 1.0 m. No artifact-rejection algorithm
was used in our study. Examples of FVEP and PVEP
traces from two patients are presented in Figure 2, the
peak times and amplitudes of the P2 wave of FVEP
and the P100 wave of PVEP were recorded and
compared.
Statistical Analysis
All statistical analyses were performed using the
Statistical Package for the Social Sciences (SPSS ver.
19.0; SPSS, Inc., Chicago, IL). All continuous
variables, including age, BCVA, IOP, ocular structure
measurements, peak time, and VEP amplitude, were
recorded as the mean 6SD. Normal distributions of
age, BCVA, IOP, ocular structure measurements,
peak time, and VEP amplitude were tested using the
Shapiro-Wilk test. Differences between cataractous
and contralateral healthy eyes regarding the afore-
mentioned parameters were measured by a paired t-
test. The relationships between BCVA and VEP
parameters were calculated by partial correlation
analysis with age controlled. The level of significance
was P,0.05.
Results
We studied 25 patients with unilateral posterior
CC (10 girls, 15 boys; mean age, 73.3 628.0 months/
5.6 62.4 years, range, 39–164 months/3.3–14.0
years). BCVA of cataractous eyes was worse than
that of the contralateral healthy eyes (t¼9.872, P,
0.001), and no difference in the IOP between two eyes
was found (t¼0.91, P¼0.38; Fig. 3).
The ocular structure parameters are shown in
Table 1, including CA, km, CCT, ACD, and AL.
Compared to contralateral healthy eyes, larger CA
and deeper ACD were found in cataractous eyes (P¼
0.002 and 0.009, respectively).
All 25 patients completed the FVEP examinations,
and 20 and 11 successfully completed PVEP-600and
PVEP-150examinations, respectively. The relation-
ships between visual acuity and VEP parameters in
young patients were further analyzed (Fig. 4). Slight
positive relationships between BCVA and peak time
of VEP (PVEP-600and -150Figs. 4c,4e) and negative
relationships between BCVA and VEP amplitude
(FVEP and PVEP-150;Figs. 4b,4f) were revealed.
However, no linear relationships between BCVA and
VEP parameters were statistically significant (P
values of partial correlation analysis ranged from
0.149–0.994).
The peak time and amplitude of FVEP, PVEP-600,
and PVEP-150between cataractous and contralateral
healthy eyes also were compared using a paired t-test.
The peak time of P100 of PVEP-600in cataractous
eyes was longer than that in contralateral healthy eyes
(114.9 618.8 vs. 105.0 612.4 ms, t¼2.74, P¼0.013;
Fig. 5). Amplitudes of P100 of patterns PVEP-600and
-150in cataractous eyes were smaller than those in
contralateral healthy eyes (PVEP-600, 15.2 65.3 vs.
19.9 610.4 lV, t¼2.47, P¼0.023; PVEP-150, 10.4
67.0 vs. 22.1 611.9 lV, t¼3.00, P¼0.012).
Discussion
We recently proposed a novel CC category system,
including total, anterior, interior, and posterior
cataracts, based on the anterior segment characteris-
tics, with the aim of facilitating CC treatment.
Posterior CC, one type of CC (based on our novel
category system) with seemingly mild lens opacity and
a small affected area, has the most controversial
3TVST j2018 jVol. 7 jNo. 4 jArticle 9
Lin et al.
Figure 2. Examples of FVEP and PVEP traces. The traces of healthy and cataractous eyes were artificially overlapped for a better
comparison and illustration. (a) These FVEP traces were obtained from two eyes of a 5-year-old boy (patient CJX). (b) These PVEP-600
traces were obtained from two eyes of a 4.5-year-old girl (patient HXY). FVEP, flash visual evoked potentials; P, peak time; A, amplitude; R,
reliability.
Figure 3. Comparisons of BCVA and IOP between cataractous eyes and contralateral healthy eyes. The dotted lines indicate the mean
values, the red and yellow bands on both Figures indicate 95% confidence intervals.
4TVST j2018 jVol. 7 jNo. 4 jArticle 9
Lin et al.
treatment option among all categories. In our study,
we comprehensively investigated the influences of
unilateral posterior lens opacity on visual function
and ocular structure in patients with posterior CC and
further explored the clinical treatment guidance of
our novel CC category system for CC patients.
Alteration of ocular structure parameters is the
most direct marker of visual impairment in CC
patients. Similar to other reports
14,15
and to our
previous study,
11
larger CA and deeper ACD were
found in cataractous than in healthy contralateral
eyes in our study. The higher CA in eyes with CC
likely resulted from a delayed separation of the lens
from the surface ectoderm during fetal develop-
ment.
16
The deeper ACD in patients with CC may
be explained by the special type of cataracts in our
study. According to the novel CC category system
related to anterior segment characteristics proposed
by Lin et al.,
3
eyes with posterior cataracts trended
toward deeper ACD than eyes with a clear lens, which
is consistent with our current findings. Inappropriate
management of the larger CA and deeper ACD can
lead to development of an unexpected refractive error
and, therefore, requires attention.
Ocular structure is the foundation of visual
function; thus, we analyzed the functional impair-
ments of patients with posterior CC that were caused
by the reported abnormal ocular structures. The
influence of lens opacity on visual function can be
reflected directly by decreased visual acuity, and the
BCVAs of cataractous eyes were significantly worse
than those of contralateral healthy eyes. However,
visual acuity that is severely affected by lens opacities,
can merely show the current visual condition of
patients with CC and cannot truly reflect the
functional integrity of the retina and visual pathway
independent of lens opacity. VEP, which originates in
the visual cortex and can be extracted from brain
waves by repeated superposition averaging, has been
reported previously as a useful objective method to
assess visual function with minimal impact of lens
opacity.
17
We also analyzed the relationships between
BCVA and VEP parameters, where no significant
linear relationship was found, which further confirms
the different aspects of vision reflected by BCVA and
VEP examinations. However, slight linear relation-
ships between BCVA and VEP parameters were
revealed in PVEP-150(BCVA and peak time, PCC ¼
0.383; BCVA and amplitude, PCC ¼0.455). The
relationship between visual acuity and PVEP param-
eters with small checkerboard still required further
investigation. Compared to contralateral healthy eyes,
prolonged peak time and smaller amplitudes of
cataractous eyes were detected in patients with
unilateral posterior CC, which is consistent with
previous findings.
18
The prolonged peak time and
small amplitudes may have resulted from deprivation
amblyopia caused by congenital lens opacities.
Competition and suppression between two eyes in
unilateral patients prevent the affected eye from
normal visual stimulation that promotes healthy
development of visual function during the sensitive
period, which is reflected by the weakened VEP
response in our study. Therefore, surgical treatment
should be considered in posterior CC patients, even
though this CC condition has mild and small-area
lens opacities. However, the prognosis of patients
with amblyopic unilateral CC remains unfavorable,
even after surgical intervention at 6 weeks of age.
19
Meanwhile, mean patient age in our study was 73.3
months, indicating that delayed treatment of unilat-
eral CC remains common in China. Thus, better
education regarding CC management and a detailed
explanation of the potential for poor postoperative
Table 1. Comparisons of the Ocular Biological Structure Parameters Between Cataractous and Contralateral
Healthy Eyes
Cataractous Eye Healthy Eye tP
CA (D) 1.8 61.2 0.9 60.4 3.54 0.002*
Km (D) 43.5 61.6 42.9 60.9 1.80 0.09
CCT (lm) 542.6 640.4 538.8 636.4 0.41 0.68
ACD (mm) 3.7 60.3 3.5 60.4 2.89 0.009*
AL (mm)
a
22.6 61.8 22.4 60.5 0.55 0.59
D, diopters.
a
Available for 15 children;
* Paired t-test, statistically significant at P,0.05.
5TVST j2018 jVol. 7 jNo. 4 jArticle 9
Lin et al.
visual function for this type of CC are essential for
parents of patients with CC.
Our study has certain limitations. First, only 11
patients were tested successfully by PVEP-150exam-
inations; others failed due to poor vision of the
affected eye, low reliability index of examination, or
indistinguishable P100 waveform. Therefore, the
relationship between BCVA and FVEP-150parame-
ters,aswellasthecomparisonofFVEP-15
0
parameters between affected and healthy eyes in
Figure 4. Scatterplots for BCVA and VEP parameters in cataractous eyes of patients with unilateral posterior CC. No significant linear
relationship was found between BCVA and VEP parameters. Number of patients: 25 in (a) and (b); 20 in (c) and (d); 11 in (e) and (f); PCC,
partial correlation coefficient.
6TVST j2018 jVol. 7 jNo. 4 jArticle 9
Lin et al.
unilateral posterior CC patients revealed in our study
should be interpreted with caution. Second, because it
is difficult for young children to cooperate in the
examinations for a long time, each VEP condition was
recorded only once with 60 valid responses overlaying
and averaging. Third, the influence of age on VEP
parameters should be addressed carefully so that VEP
responses of young patients may not be completely
matured. Peak time of VEP showed maturational
changes and continued to decrease until different
reported ages (most of which were before 1 year).
20–23
In our study, all participants were .3.5 years old
(mean age, 5.6 years), which could minimize the
effects of the confounding factor of age. However,
previous studies revealed that amplitude maturated
much slower than peak time.
24,25
Therefore, we
further statistically controlled the effects of age by
partial correlations analysis when calculating the
relationships between BCVA and VEP parameters.
Furthermore, retinal function was not evaluated in
our study. An objective examination, such as electro-
retinogram, of retinal function would be included to
rule out mild retinal dysfunction in our next study.
Additionally, the relatively small number of patients
with unilateral posterior CC still limits the extent to
which the results can be generalized. Finally, because
this was a preliminary study, only one type of our
novel CC category system with controversial treat-
ment options was evaluated. The visual function of
other CC types still requires further investigations.
Nevertheless, we comprehensively evaluated visual
function and ocular structure of patients with
unilateral posterior CC, one type of CC in our novel
CC category system with two controversial treatment
options. According to our results, impaired visual
function and ocular structure were detected in
patients with posterior lens opacity. Timely surgery
and a detailed explanation of the potential for poor
postoperative visual function in this type of CC can
be considered. This study could provide a reference
for further study of visual impairments for other types
of CC in our novel CC category system and promote
clinical treatment guidance effects of our novel CC
category system.
Acknowledgments
Supported by the National Natural Science Foun-
dation of China (NSFC; 81770967, 91546101,
81300750), Clinical Research and Translational Med-
ical Center of Pediatric Cataract in Guangzhou City
(201505032017516), Youth Pearl River Scholar Fund-
ed Scheme (2016–2018), Guangdong Provincial Foun-
dation for Medical Scientific Research (A2015340),
and Fundamental Research Funds for the Central
Universities (16ykjc28).
The sponsors of the study had no role in the study
protocol design, data collection, data analysis, data
interpretation, manuscript preparation, or decision to
submit the manuscript for publication.
DRL, JJC, and HTL contributed to the concep-
tion or design of the work; DRL, JJC, ZZL, XHW,
QZC, and ZLL contributed to the acquisition of
Figure 5. Comparisons of the peak time and amplitude of VEP between both eyes of patients with unilateral posterior CC. (a) The peak
time of P100 of PVEP-600in cataractous eyes was longer than that in contralateral healthy eyes. (b) The amplitudes of P100 of patterns
VEP-600and -150in cataractous eyes were smaller than those in contralateral healthy eyes. Error bar: standard deviation; * Paired t-test,
statistically significant at P,0.05.
7TVST j2018 jVol. 7 jNo. 4 jArticle 9
Lin et al.
data;DRLandXYLcontributedtotheanalysis;
DRL, JJC, and ZZL contributed to the interpreta-
tion of data for the work; and HTL and DRL
contributed to drafting the work and revising it
critically for important intellectual content. All
authors gave final approval of the version to be
published; HTL, WRC, and DRL agree to be
accountable for all aspects of the work.
Disclosure: D. Lin, None; J. Chen, None; Z. Liu,
None; Z. Lin, None; X. Li, None; X. Wu, None; Q.
Cao, None; H. Lin,W. Chen, None; Y. Liu, None
*DL, JC, and ZL contributed equally to this
article.
References
1. Wu X, Long E, Lin H, Liu Y. Prevalence and
epidemiological characteristics of congenital cat-
aract: a systematic review and meta-analysis. Sci
Rep. 2016;6:28564.
2. Reddy MA, Francis PJ, Berry V, Bhattacharya
SS, Moore AT. Molecular genetic basis of
inherited cataract and associated phenotypes.
Surv Ophthalmol. 2004;49:300–315.
3. Lin H, Lin D, Liu Z, et al. A novel congenital
cataract category system based on lens opacity
locations and relevant anterior segment charac-
teristics. Invest Ophthalmol Vis Sci. 2016;57:6389–
6395.
4. Datiles MB, Hejtmancik JF. Congenital cata-
racts: classification and association with anterior
segment abnormalities. Invest Ophthalmol Vis Sci.
2016;57:6396.
5. Zhang L, Wu X, Lin D, et al. Visual outcome and
related factors in bilateral total congenital cata-
ract patients: a prospective cohort study. Sci Rep.
2016;6:31307.
6. Zhu M, Zhu J, Lu L, He X, Zhao R, Zou H.
Four-year analysis of cataract surgery rates in
Shanghai, China: a retrospective cross-sectional
study. BMC Ophthalmol. 2014;14:3.
7. Fuest M, Plange N, Jamali S, et al. The effect of
cataract surgery on blue-yellow and standard-
pattern visual-evoked potentials. Graef’s Arch
Clin Exp Ophthalmol. 2014;252:1831–1837.
8. Fuest M, Kieckhoefel J, Mazinani B, et al. Blue-
yellow and standard pattern visual evoked
potentials in phakic and pseudophakic glaucoma
patients and controls. Graef’s Arch Clin Exp
Ophthalmol. 2015;253:2255–2261.
9. Lin D, Chen J, Lin Z, et al. 10-year overview of
the hospital-based prevalence and treatment of
congenital cataracts: the CCPMOH experience.
PloS One. 2015;10:e0142298.
10. Lin H, Chen W, Luo L, et al. Ocular hypertension
after pediatric cataract surgery: baseline charac-
teristics and first-year report. PloS One. 2013;8:
e69867.
11. Lin D, Chen J, Liu Z, et al. Prevalence of corneal
astigmatism and anterior segmental biometry
characteristics before surgery in Chinese congen-
ital cataract patients. Sci Rep. 2016;6:22092.
12. Creel DJ. Visually evoked potentials. In: Kolb H,
Fernandez E, Nelson R, eds. Webvision: The
Organization of the Retina and Visual System. Salt
Lake City, UT: University of Utah Health
Sciences Center; 1995.
13. Odom JV, Bach M, Brigell M, et al. ISCEV
standard for clinical visual evoked potentials:
(2016 update). Doc Ophthalmol Adv Ophthalmol.
2016;133:1–9.
14. Watanabe T, Matsuki N, Yaginuma S, Nagamo-
to T. [Corneal astigmatism in children with
congenital cataract]. Nippon Ganka Gakkai Zas-
shi. 2014;118:98–103.
15. Trivedi RH, Wilson ME. Biometry data from
Caucasian and African-American cataractous
pediatric eyes. Invest Ophthalmol Vis Sci. 2007;
48:4671–4678.
16. Bouzas AG. Anterior polar congenital cataract
and corneal astigmatism. J Ped Ophthalmol Strab.
1992;29:210–212.
17. Lin D, Chen J, Lin H, Chen W. Application of
visual electrophysiology for the diagnosis and
treatment of cataracts. Eye Sci. 2015;30:190–197.
18. McCulloch DL, Skarf B. Pattern reversal visual
evoked potentials following early treatment of
unilateral, congenital cataract. Arch Ophthalmol.
1994;112:510–518.
19. Ejzenbaum F, Salomao SR, Berezovsky A, et al.
Amblyopia after unilateral infantile cataract
extraction after six weeks of age. Arq Brasil
Oftalmol. 2009;72:645–649.
20. Lenassi E, Likar K, Stirn-Kranjc B, Brecelj J.
VEP maturation and visual acuity in infants and
preschool children. Doc Ophthalmol Adv Oph-
thalmol. 2008;117:111–120.
21. Kraemer M, Abrahamsson M, Sjostrom A. The
neonatal development of the light flash visual
evoked potential. Doc Ophthalmol Adv Ophthal-
mol. 1999;99:21–39.
22. Benavente I, Tamargo P, Tajada N, Yuste V,
Olivan MJ. Flash visually evoked potentials in
the newborn and their maturation during the first
8TVST j2018 jVol. 7 jNo. 4 jArticle 9
Lin et al.
six months of life. Doc Ophthalmol Adv Oph-
thalmol. 2005;110:255–263.
23. McCulloch DL, Skarf B. Development of the
human visual system: monocular and binocular
pattern VEP latency. Invest Ophthalmol Vis Sci.
1991;32:2372–2381.
24. Madrid M, Crognale MA. Long-term maturation
of visual pathways. Vis Neurosci. 2000;17:831–
837.
25. Mahajan Y, McArthur G. Maturation of visual
evoked potentials across adolescence. Brain
Devel. 2012;34:655–666.
9TVST j2018 jVol. 7 jNo. 4 jArticle 9
Lin et al.
