386 Arq Bras Oftalmol. 2013;76(6):386-90
Artigo de Revisão | Review ARticle
Visual acuity measures the ability to recognize object details.
Once it is measured under controlled distance, light and contrast
conditions, visual acuity does not reﬂect the real quality of vision.
External factors as indirect light can aﬀect this quantitative assess-
ment. Clinical ophthalmology commonly uses visual acuity opto-
types only in order to assess the entire visual function(1).
Several previous epidemiological and clinical studies rely of visual
functions measurements as the primary outcome, despite these
measurements are crucial to understand the real patient’s visual abi-
lity. Visual acuity does not express the real vision conditions and the
subjective aspects of world perception by the patient(2).
The most common vision quantiﬁcation test is the spatial deter-
mination of visual acuity through the Snellen chart. Letters displayed
have two basic characteristics: size and contrast(3). This test assesses
the smallest identiﬁed font, keeping constant the black letters high
contrast relative to the white background on which they are displayed.
The degree of visibility of a given ﬁgure may be altered by reducing its
contrast to a level which it is no longer recognized, regardless its size(4).
In view of the fact that excellent visual acuity is expected from
cataract and refractive surgery, the need for measurement of broader
aspects of visual function has increased. Some patients with mode-
rate visual acuity preoperatively might not be prepared to accept a
postoperative visual acuity that, despite being good, is blurred by
troublesome glare or disturbed by loss of contrast sensitivity. When
a patient complains of glare, there are distinct visual phenomena he
might be complaining of(5).
Quality of vision is diﬃcult to deﬁne by a single parameter. Some
patients are dissatisﬁed with their quality of vision after excimer laser
refractive surgery even though their Snellen acuity is 20/20 (1.0) or
better. Higher-order aberrations, image degradation, and contrast
acuity have been implicated as reasons for patient’s dissatisfaction(6).
Glare disability is another parameter that correlates with visual com-
plaints after refractive surgery(7).
The purpose of this review is to explain the diﬀerent components
of the visual function and to describe available methods to assess the
aspects of quality of vision.
Functional vision is our everyday vision. Diﬀerent tasks in our daily
life use diﬀerent parts of our visual system. It reﬂects our vision in real-
world situations, where we have to see both smaller high-contrast
images and larger low-contrast ones. Our cognitive perception, the
health of our visual system and our brain processing function, all play
critical roles on how well we see the world(8).
Vision scientists are particularly concerned with how well the eye’s
retina transforms a visual image into neural code. That is how our eyes
work with our brain to translate images into visual perception(9-13).
The retina/brain system also ﬁlters the image into diﬀerent sizes
and levels of contrast(10,11). Many properties come into play at the
cortical level that impacts the ﬁnal process of the visual information.
These include attention, expectancy, memory, identiﬁcation and
other cognitive perceptual properties. When examining the comple-
Quality of vision in refractive and cataract surgery, indirect measurers: review article
Qualidade visual em cirurgia refrativa e catarata, medidores indiretos: artigo de revisão
Taís RenaTa RibeiRa PaRede1, andRé augusTo MiRanda ToRRicelli1, adRiana Mukai2, MaRcelo VieiRa neTTo1, saMiR Jacob bechaRa1
Submitted for publication: June 12, 2012
Accepted for publication: July 25, 2013
Study carried out at Universidade de São Paulo - São Paulo (SP), Brazil.
1 Physician, Department of Ophthalmology, Medical School, Universidade de São Paulo - São Paulo
2 Technician in Ophthalmology, Department of Ophthalmology, Medical School, Universidade de
São Paulo - São Paulo (SP), Brazil.
Funding: No specific financial support was available for this study.
Disclosure of potential conflicts of interest: T.R.R.Parede, None; A.A.M.Torricelli, None; A.Mukai,
None; M.V. Netto, None; S.J.Bechara, None.
Correspondence address: Taís Renata Ribeira Parede. Avenida Doutor Enéas de Carvalho Aguiar,
155 - Instituto Central - 6o andar - Departamento de Oftalmologia / Setor de Cirurgia Refrativa -
São Paulo (SP) - 05403-000 - Brazil - E- mail: email@example.com
Visual acuity is the measurement of an individual’s ability to recognize details of an
object in a space. Visual function measurements in clinical ophthalmology are limited
by factors such as maximum contrast and so it might not adequately reﬂect the
real vision conditions at that moment as well as the subjective aspects of the world
perception by the patient. The objective of a successful vision-restoring surgery lies
not only in gaining visual acuity lines, but also in vision quality. Therefore, refractive
and cataract surgeries have the responsibility of achieving quality results. It is diﬃcult
to deﬁne quality of vision by a single parameter, and the main functional-vision tests
are: contrast sensitivity, disability glare, intraocular stray light and aberrometry. In the
current review the diﬀerent components of the visual function are explained and
the several available methods to assess the vision quality are described.
Keywords: Vision; Refractive surgical procedure; Cataract extraction; Contrast sensi-
tivity; Vision, ocular/physiology; Aberrometry; Vision tests
Qualidade Visual é a medida da capacidade individual de reconhecer detalhes de um
objeto no espaço. Medições de função visual na clínica oftalmológica são limitadas por
vários fatores, tal como máximo contraste e assim podem não refletir adequadamente
as condições visuais reais, bem como os aspectos subjetivos da percepção do mundo
pelo paciente. O sucesso em uma cirurgia está não apenas em restaurar linhas de
visão, mas sim qualidade visual. Portanto, as cirurgias refrativas e de catarata têm a
responsabilidade de alcançar resultados de qualidade. É difícil definir qualidade visual
por um único parâmetro, sendo os principais testes de função visual: sensibilidade ao
contraste; glare; dispersão intraocular da luz e aberrometria. Nesta revisão os diferentes
componentes da função visual são explicados e os diversos métodos disponíveis para
se avaliar a qualidade de visão são descritos.
Descritores: Visão; Procedimentos cirúrgicos refrativos; Extração de catarata; Sensi-
bilidades de contraste; Visão ocular/fisiologia; Aberrometria; Testes visuais
Parede TRR, et al.
Arq Bras Oftalmol. 2013;76(6):386-90
xity of our visual system, it is easy to see how the quality of input can
impact the quality of our visual experience(10,11).
A channel model represents how diﬀerent vision cells, or chan-
nels, handle diﬀerent aspects of vision, such as color, size, shape,
contrast and motion. Each visual channel collects diﬀerent bits of
information for these varying aspects of vision and individually
transmits them to the brain to be processed and assembled into a
Everything we see is broken down into a range of spatial frequen-
cies, or channels. Channels are size-selective. Our visual system uses
these diﬀerent channels to see in high- and low-contrast situations.
Our visual perception is the combination of all these channels(8,9).
The channels that are used to see the letters on the 20/20 visual
acuity test might be diﬀerent from that ones that help us to see ob-
jects in our everyday lives. Because these channels are independent
from each other, we need to test the sensitivity of each channel
separately to determine how well diﬀerent-size objects are seen(8,14).
FUNCTIONAL VISION PERFORMANCE TESTS
The clinical evaluation of the quality of vision performance before
and after an ophthalmologic surgery includes: the ability to detect
contrasts; vision in diﬀerent light levels; aberrations.
Contrast sensitivity refers to the ability of the visual system to
dis tinguish between an object and its background. According to
the channel model of vision, size-selective contrast cells are used to
detect the diﬀerences between light and dark parts of an object and
the background against which it is seen.
There are diﬀerent available tests for the evaluation of contrast
sensitivity. The main diﬀerence among them is the target type.
Charts that use letters, numbers or symbols in decreasing con-
trast are usually called low-acuity contrast tests, while those that
use circles with bars or waves are called contrast sensitivity tests. For
each kind of test, the least amount of contrast that can be perceived
by an observer is displayed in graphs created by the manufacturers
themselves, giving rise to the “line of contrast sensitivity” for each
patient and the patient’s ability to distinguish contrast sensitivity in
relation to the normal range.
In some tests, depending on the logarithmic scale of contrast
sensitivity, the patient might be classiﬁed as having normal vision,
visual impairment or low vision.
There are two kinds of contrast sensitivity tests presently em-
ployed: grating tests and letter contrast sensitive.
Sine-wave gratings tests(8-10)
Sine-wave gratings (Figure 1) are used to create and test the con -
trast sensitivity curve. A sine-wave grating is a repeated number of
fuzzy dark and light bars, or cycles. The number of grating cycles over
a speciﬁed visual angle determines its spatial frequency.
A small number of cycles over a speciﬁed visual angle are deﬁned
as having a low spatial frequency. A large number of them over the
same visual angle are deﬁned as having a high spatial frequency. Con-
trast is the diﬀerence between the grating’s brightness and darkness.
The visual system ﬁlters the images we see into independent
ranges of sizes, or spatial frequencies. In vision testing, sine-waves of
varying spatial frequencies (sizes) and contrast are needed to test the
visual channels involved in functional vision.
The most commonly used tests are: Vision Contrast Test System
(VCTS 6500 e 6000) (Vistech, Dayton, OH), Contrast Sensitivity Vision
(CSV 1000 E) (VectorVision, Greenville, OH) and Functional Acuity
Contrast Test (FACT) (Vision Science Research Corporation, Walnut
Environment conditions considerations to grating tests are shown
on table 1.
Letter contrast sensitivity(8,9,13)
Letter contrast sensitivity (Figure 2) is similar to low-contrast
acuity in that the patient’s task is to read as many letters as possible
from a chart. Although in the contrast sensitivity test all letters have
the same size and are large enough to be legible whenever they can
be seen at all, their contrast is progressively reduced, from near 100%
at the top of the chart, to near 0% at its bottom.
The ability to see low-contrast letters is important for reading
signs and identifying low-contrast objects that are similar in size
to the test letters. However, letter contrast sensitivity test results
may not be inferred to real life situations that involve detection and
recognition of objects that are either much larger or much smaller
than the chart letters.
The most commonly used tests are: Test Bailey-Lovie Chart or
Regan (The National Vision Research Institute, Australia), that use
Early Treatment Diabetic Retinopathy Study (ETDRS) Chart (Precision
Vision) and Pelli-Robson (Haag-Streit, Mason, OH, USA).
Environment considerations to letter tests are also shown on table 1.
WhiCh Contrast sensitivity test is the best?
A comparison of Contrast Sensitivity Tests Research shows that
the “Contrast Sensitivity Curve” provided by sine-wave grating tests
is more sensitive and informative than the results obtained from low-
contrast letter-acuity systems(8).
Some investigators believe grating tests of contrast sensitivity
are superior to letter contrast sensitivity charts. Their arguments em-
phasize that, in clinical research, it is important to assess the broad
contrast sensitivity function from low to high spatial frequencies,
as this function reﬂects the visual system’s multiple spatial ﬁlters(15).
A number of authors have concluded that test-retest reliability
of the sine-wave grating tests may be problematic for their intended
purpose of screening and tracking change(15-18). The good test-retest
reliability of the letters chart, relative immunity from varying test
conditions, ease the brevity of administration (3-5 minutes), and
availability of published normative data(19), have led to its frequent
choice for epidemiological studies(20-23).
vision in different light levels - “glare test”
It refers to the temporary loss of visual function in the presence of
a bright adjacent light source. Common sources of disability glare for
Figure 1. FACT sine-wave grating chart tests ve spatial frequencies (sizes) and nine levels
of contrast. The patient determines the last grating seen for each row (A, B, C, D and E)
and reports the orientation of the grating: right, up or left. The last correct grating seen
for each spatial frequency is plotted on a contrast sensitivity curve.
Quality of vision in refractive and cataract surgery, indirect measurers: review article
388 Arq Bras Oftalmol. 2013;76(6):386-90
drivers are the sun and headlights from oncoming cars. Susceptibility
to glare sources varies greatly from person to person, depending on
the amount of light that is scattered into the retina from the crystalli-
ne lens and other eye structures. A clinical test that could accurately
predict the eﬀects of glare and light-scattering sources on driving
performance should be a valuable diagnostic tool for evaluating new
medical products that physically produces the light scatter or aﬀects
how one realizes the intraocular light scatter. Several disability glare
tests have been developed for clinical use(24-25).
In most tests, especially those that involve measuring contrast
sensitivity or visual acuity in the presence of a continuous, static glare
source, its light may cause the pupil to constrict enough to aﬀect the
results of the glare measurement(26).
Advantage of these tests is that they eliminate the needs to control
the levels of room light and can be used in a small space (Table 1)(27).
Available tools to measure disability glare are: Optec 6500 P
(Stereo Optical Company, Inc, Chicago, Illinois, USA), CST 1800 digital
(Vision Sciences Research Corporation, Walnut Creek, California) and
CSV 1000HGT (VectorVision, Greenville, OH).
Intraocular stray light
A diﬀerent approach to assess the eﬀects of disability glare on
visual function is to obtain a direct measurement of the amount of
stray light in the eye produced by a glare source. Oculus Instruments
(Oculus, Optikgeräte, Wetzlar- Dutenhofen, German) have recently
marketed the C-Quant Stray light Meter® (Figure 3) developed by van
den Berg and Ijspeert(28-30).
The device, currently marketed in the United States, eﬀects a tem-
poral variation in the stray light from a ﬂickering glare source, which
is nulliﬁed by a superposed light ﬂickering out of phase with the stray
light. The amount of added light that just cancels out the stray light
ﬂicker is a direct measurement of the stray light. The test is fast, easy for
the patient, and accurate. However, the correlation between the stray-
light results from this test and the results of contrast sensitivity with
glare tests and the real life conditions, have not been established(2).
Aberrometry allows the objective evaluation of visual quality. It is
a technological modality that studies the propagation of light from
the physical optic analysis. In an optical homogeneous system the
Table 1. Comparison of Contrast Sensitivity test and Glare test methodologies
Methodology Tests Pros Cons
Sine-waves grating tests VCTS 6500
Assesses the whole contrast sensitivity function
from lowest to highest spatial frequencies
Time consuming; results are more variable
than standard acuity test results
Letter contrast sensitivity
Quick, easy, good predictor of performance for
high resolution tasks under bright
and low light conditions
If photopic conditions: Poor predictor of performance under low
contrast conditions. If mesopic condition: Test conditions diﬃcult to
control and results are more variable than photopic results
Letter contrast sensitivity PELLI-ROBSON Assesses performance for
reading low contrast signs
May not provide an accurate assessment of performance detecting
and recognizing objects with sizes diﬀerent than the chart letters
Disability glare OPTEC 6500
Adding glare testing to vision tests adds
information about the eﬀects of intraocular light
scatter on visual performance
Time consuming; results are more variable
than standard acuity test results
Intraocular straylight C- QUANT Fast, easy for the patient, and accurate Correlation between straylight results and other vision tests with
glare, and driving performance not yet established
VCTS= vision contrast test system; CSV= standardized contrsts sensitivity; FACT= functional acuity contrast test; ETDRS= Early Treatment Diabetic Retinopathy Study; CST= contrast
sensitivity tester; C-Quant= cataract-quantiﬁer.
Figure 2. Pelli-Robson test measures contrast sensitivity using a single large letter size
(20/60 optotype), with contrast varying across groups of letters. Specically, the chart uses
letters (6 per line), arranged in groups whose contrast varies from high to low. Patients
read the letters, starting with the highest contrast, until they are unable to read two or
three letters in a single group. Each group has three letters of the same contrast level,
so there are three trials per contrast level. The subject is assigned a score based on the
contrast of the last group in which two or three letters were correctly read. The score,
a single number, is a measure of the subject’s log contrast sensitivity. Thus a score of 2
means that the subject was able to read at least two of the three letters with a contrast of
1 percent (contrast sensitivity = 100 percent or log 2). A Pelli-Robson score of 2.0 indicates
normal contrast sensitivity of 100 percent. Scores less than 2.0 signify poorer contrast
sensitivity. Pelli-Robson contrast sensitivity score of less than 1.5 is consistent with visual
impairment and a score of less than 1.0 represents in visual disability.
Parede TRR, et al.
Arq Bras Oftalmol. 2013;76(6):386-90
light propagates uniformly from a point of light, at the same speed
in all directions. When this wavefront hits on an ideal lens, it creates
a single focal point. In real lenses, the spread of the wavefront is
modiﬁed, so paracentral and peripherals rays propagate in several
wavefronts, not coinciding in a single focal point. This phenomenon
is known as monochromatic aberration.
The human eye is not a perfect optical system, but the aberrations
can be partially compensated due to the aspherical corneal shape
and the asphericity of the lens, that bring an attenuation of optical
The wavefront analysis measures the diﬀerence between the
aberrations of a real wavefront, measured in an optical system and
an ideal wavefront, through an ideal optical system. These diﬀerences
are the characteristic of each optical system, of each human eye.
The optical aberrations that can be corrected are the monochro-
matic ones (which have a single wavelength of visible light), and
these can be quantitatively schematized in Zernike Polynomial. This
polynomial describes the wavefronts in three dimensions: x, y and z.
Thus, the ﬁnal wavefront of an optical system is the sum of Zernike
Polynomials that represents all strains of this system.
In the Polynomial, the aberrations are decomposed in lower order
aberrations (zero until second order) and higher order aberrations
(third until tenth order).
Lower order aberrations, denominated tilt, defocus and astigma-
tism, represent 85% of the total ocular aberrations in normal eyes
and are able to be corrected by spherocylindrical optical systems or
conventional refractive surgery.
Higher order aberrations represent 15% of ocular aberrations in nor-
mal eyes. There are aberrations that limit vision, and can not be corrected
with spherocylindrical lenses or conventional refractive surgeries. The
most relevant are coma, spherical aberration, trefoil and tetrafoil.
It is believed that higher order aberrations are responsible for a
number of visual complaints present even in patients with normal
visual acuity in the tables for high contrast. Complaints include the
presence of halo, glare, double vision and star burst symptoms, es-
pecially at night when the dilated pupil provides greater incidence of
high order aberrations in the optical system of the eye(32).
Higher-order aberrations can be expressed numerically by the
root mean square (RMS), which measures the diﬀerence between a
wavefront in a real optical system and an ideal optical system. The
RMS represents a reliable measurement of the amount of aberration
of an optical system, is generic and does not specify the qualitative
characteristics of each aberration found.
There are, however, other aberrometric indices that measure
the quality of the images generated by an optical system, such as
Point spread function (PSF), Strehl ratio, and Modulation transfer
Point spread function
Measure how the retina views the point image after traversing
the optical system of the eye. It is graphically represented as a distor-
tion of a point on the retina varying with the captured area and the
Contrast measurement deﬁned by the ratio between the PSF of
an optical system and the PSF of a perfect optical system (limited only
by diﬀractions). The Strehl ratio value greater than or equal to 0.8 is
considered to be perfect, representative of an optical system without
aberrations. However, in the normal population, inﬂuenced by pupil
size, their values are close to zero.
Modulation transfer function
Attempts to measure image contrast. It evaluates the ability of a
system to convert an object contrast to the image plane, at a speciﬁc
resolution. In other words, it analyzes the image contrast as a function
SYSTEMS OF WAVE FRONT ANALYSIS
The system of wavefront analysis can be ingoing or outgoing. The
ingoing system studies the aberrations of the light beams projected
on the retina. The outgoing system evaluates the wave front coming
out of the eye from a light beam projected toward the retina and
reﬂected back. Thus, aberrometers can be classiﬁed according to their
standard operation: outgoing and ingoing system(28).
- Hartmann-Shack Sensor (Zywave - Baush & Lomb; WaveScan -
VISX; Wasca Analyser - Carl Zeiss-Meditec; KR-9000PW - Topcon;
Maxwel - Ziemer Ophthalmology).
Retinal imaging systems
- System of Tschening (WaveLight Wavefront Analyser - WaveLight;
ORK Wavefront Analyser-Schwind)
- Ray Tracing (Trace VFA; i- Trace- Tracey)
Double pass system
- Slit retinoscopy (OPD- Scan - Nidek; OQAS- Visopmetrics S.L.)
The quantitative and qualitative information provided by the
study of the wavefront of each human eye, can help to decode each
optical system separately and proceed surgically to reduce the high
order aberrations, providing better visual quality to the patient. It is
the custom refractive surgery, based on aberrometrical discrimina-
tion, in the wavefront analysis of each human eye(34).
Our cognitive perception, the health of our visual system, and
the processing function of our brain all play critical roles on how well
we see the world. Vision researchers are still developing better tests
to analyze visual system and to understand all variables involved in
the visual acuity(8).
The current objective of a successful vision-restoring eye surgery
is not only to gain lines in visual acuity, but also to achieve quality of
vision. Therefore, refractive and cataract surgeries aim higher quality
standards for their results.
Figure 3. Example of a patient’s view of a straylight test, modied from van den Berg et
al.(24). The patient is presented with two alternative forced choices and asked to choose
between the stronger of two ickers presented in controlled background lights. The
test duration is one to two minutes per eye. The straylight test has an internal analysis
procedure that yields a reliability estimate called the expected standard deviation (ESD),
which was developed to control and increase the internal reliability of the test. Only
reliable test results (ESD ≤0.08 log units) should be accepted.
Stray light source:
1 - Stray light only
2 - Stray light + variable
counterphase ickering light
Quality of vision in refractive and cataract surgery, indirect measurers: review article
390 Arq Bras Oftalmol. 2013;76(6):386-90
A detailed patient’s clinical history, his visual demands and oph -
thalmological characteristics at the preoperative clinical examination
are important in planning a successful surgery. Besides the diagnosis
of lens opacity or refractive error to be corrected, contrast sensitivity,
glare and wavefront analysis (aberrometry) should also be conside-
red when planning a surgical procedure.
When evaluating the safety and eﬀectiveness of medical pro-
ducts, it is important to assess their eﬀects on the performance of
“real-world” visual tasks. However, tests of visual performance are not
yet standardized, and no consensus has been reached on the ability
of existing clinical vision tests to predict real-world performance(28).
Most currently available clinical vision tests were developed as
general-purpose diagnostic tests for visual system disorders. Spe-
ciﬁc validation studies are still needed to identify individual tests or
combinations of them that might accurately and consistently predict
Assessment of visual performance is often important in evalua-
ting the safety and eﬀectiveness of new drugs and medical devices,
but it is typically complex, expensive and burdensome for subjects
and investigators. Identiﬁcation of clinical tests that could serve as
acceptable reference for visual-performance tests in clinical trials
would yield major savings of time, eﬀort, and expense in the evalua-
tion of new products.
Studies that isolate the visual aspects of performance should
increase the chances of revealing their true correlations with clinical
measures of visual function(28).
Given all the technology available today to achieve excellence in
visual quality, such as customized refractive surgery, aspheric, toric
and intraocular phakic lens, should it be satisfactory to rely on just
one visual acuity, high-contrast test, without further relevant infor-
mation about the optical system of each patient? So how to take
advantage of all current available technology?
Perhaps spending more time on patient evaluation, using tests
that provide valuable information on the particular characteristics
of each optical system, and so improving our clinical and surgical
decisions to meet the patient’s expectations.
1. Dick HB, Krummenauer F, Schwenn O, Krist R, Pfeiﬀer N. Objective and subjective
evaluation of photic phenomena after monofocal and multifocal intraocular lens
implantation. Ophthalmology. 1999;106(10):1878-86.
2. Massof RW, Rubin GS. Visual function assessment questionnaires. Surv Ophthalmol.
3. Wolfe JM. An introduction to contrast sensitivity testing. In: Nadler MP, Miller D, Nadler
DJ, editors. Glare and contrast sensitivity for clinicians. New York: Springer-Verlag;
4. Monteiro ML. Contribution to the study of contrast sensitivity in patients with
hemianopsia deﬁciency attributed to pituitary tumors [Tese]. São Paulo: Faculty of
Medicine; Universidade de São Paulo; 1992.
5. Koch DD. Glare and contrast sensitivity testing in cataract patients. J Cataract Refract
6. Fan- Paul NI, Li J, Sullivan Miller J, Florakis GJ. Night vision disturbances after corneal
refractive surgery. Surv Ophtalmol. 2002;47(6):533-46.
7. Vignal R, Tanzer D, Brunstetter T, Schalllhom S. [Scattered light and glare sensitivity
after wavefront-guided photorefractive (WFG-PRK) and laser in situ keratomileusis].
J Fr Ophtalmol. 2008;31(5):489- 93.
8. Ginsburg AP. Contrast sensitivity and functional vision. Int Ophthalmol Clin. 2003;
9. Ginsburg AP. Spatial ﬁltering and visual form perception. In: Boﬀ K, editot. Handbook
of perception and human performance. New York: John Wiley & Sons; 1986. p.77-88.
10. Campbell FW, Robson JG. Application of Fourier analysis to the visibility of gratings.
11. Ginsburg AP. Spatial ﬁltering and vision: implications for normal and abnormal
vision. In: Proenza LM, Enoch JM, Jampolsky A, editors. Clinical applications of visual
psychophysics. Cambrige: Cambridge University Press; 1981. p.70-106.
12. DeValois RL, DeValois KK. Spatial vision. Ann Rev Psychol.1980;31:309-41.
13. Ginsburg AP. Next general contrast sensitivit y testing. In: Rosenthal B, Cole R, editors.
Functional assessment of low vision. St Louis: Mosby Year Book; 1996. p.77-88.
14. Ginsburg AP. Forensic aspects of visual perception. In: Allen MJ, Abrams BS, Ginsburg
AP, Weintraub L. Forensic aspects of vision and highway safety. Tucson, Arizona:
Lawyers & Judges Publishing; 1996. p.201-40.
15. Owsley C. Contrast sensitivity. Ophthalmol Clin North Am. 2003; 16(2):171-7.
16. Elliott DB, Bullimore MA. Assessing the reliability, discriminative ability, and validity of
disability glare tests. Invest Ophthalmol Vis Sci. 1993;34(1):108-19.
17. Reeves BC, Wood JM, Hill AR. Vistech VCTS 6500 charts within-and-between session
reliability. Optom Vis Sci. 1991;68(9):728-37.
18. Rubin GS. Reliability and sensitivity of clinical contrast sensitivity tests. Clin Vision Sci.
19. Elliott DB, Sanderson K, Conkey A. The reliability of the Pelli-Robson contrast sensi-
tivity chart. Ophthalmic Physiol Opt. 1990;10(1):21-4. Comment in: Ophthalmic Physiol
20. Brabyn J, Schneck M, Haegerstrom-Portnoy G, Lott L. The Smith-Kettlewell Institute
(SKI) longitudinal study of vision function and its impact among the elderly: an
overview. Optom Vis Sci. 2001;78(5):264-9.
21. Klein BE, Klein R, Lee KE, Cruikshanks KJ. Associations of performance-based and
self-reported measures of visual function: the Beaver Dam Eye Study. Ophthalmic
Epidemiol. 1999;6(1):49- 60.
22. Owsley C, Stalvey BT, Wells J, Sloane ME, McGwin G Jr. Visual risk factors for crash
involvement in older drivers with cataract. Arch Ophthalmol 2001;119(6):881-7.
23. Rubin GS, West SK, Munoz B, Bandeen-Roche S, Zeger S, Schein O, et al. A comprehen-
sive assessment of visual impairment in a population of older Americans. The SEE
Study. Salisbry Eye Evaluation Project. Invest Ophthalmol Vis Sci. 1997;38(3):557-68.
24. Van den Berg TJ, Franssen L, Kruijt B, Coppens JE. History of ocular straylight measu-
rement: A review. Z Med Phys. 2013;23(1):6-20.
25. Elliott DB. Evaluating visual function in cataract. Optom Vis Sci. 1993;70(11):896-902.
26. Aslam TM, Haider D, Murray IJ. Principles of disability glare measurement: an ophthal-
mological perspective. Acta Ophthalmol Scand. 2007;85(4):354-60.
27. Drum B, Calogero D, Rorer E. Assessment of visual performance in the evaluation of
new medical products. Drug Discovery Today: Technologies [Internet]. 2007 [cited
2012 Jan 3];4(2):55-61.Available from: http://www.sciencedirect.com/science/article/
28. Ijspeert JK, van den Berg TJ. Design of a portable straylight meter. Presented at: 14°
Annual International Conference IEEE Engineering in Medicine and Biology; 1992 Oct
29-Nov 1. Paris p.1592-4. Proceeding.
29. Van den Berg TJ, Ijspeert JK. Clinical assessment of intraocular straylight. Appl Opt.
30. Van Rijn LJ, Nischler C, Gamer D, Franssen L, de Wit G, Kaper R, et al. Measurement
of stray light and glare: comparison of Nyktotest, Mesotest, stray light meter, and
computer implemented stray light meter. Br J Ophthalmol. 2005;89(3):345-51.
31. Barreto J Jr. Aberrometria. In: Bechara SJ, Garcia R, Medeiros FW, Barreto J Jr, Vieira
Netto M. Guia prático de cirurgia refrativa. Porto Alegre: Artmed; 2009. p.85-7.
32. Athaide HV, Campos M, Costa C. Study of ocular aberrations with age. Arq Bras Oftal -
33. Vieira Netto M, Ambrosio R Jr. Introdução aos sistemas disponíveis de aberrometria
ocular. In: Vieira Netto MV, Ambrosio R Jr, Schor P, Chalita MR, Chamon W, et al.
Wavefront, topograﬁa e tomograﬁa da córnea e segmento anterior. Rio de Janeiro:
Cultura Médica; 2006. p.251-2.
34. Barreiro TP, Forset Ados S, Pinto LF, Francesconi CM, Nosé W. [Wavefront-guided
Lasik for low to moderate myopia: CustomCornea versus Zyoptix]. Arq Bras Oftalmol.