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An evaluation of estimation methods for determining addition in presbyopes

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The optical correction of presbyopia must be handled individually. Our aim was to compare the methods used in addition to the refractive near vision, with the final addition used in presbyopic patients. Eighty healthy subjects with a mean age of 49.7 years (range 40 to 60 years) were studied. Tentative near additions were determined using four different techniques: one-half amplitude accommodation with minus lenses (AAL); one-third accommodative demand with positive lens (ADL); balanced range of accommodation with minus and positive lenses (BRA) and crossed cylinder test with initial myopisation (CCT). The power of the addition was then refined to arrive at the final addition. The mean tentative near additions were lower than the final addition for ADL and BRA addition methods. The mean differences between tentative and final additions were low for all the tests examined (less than 0.25 D). The intervals between the 95% limits of agreement differed substantially and were always higher than ±0.50 D. All the methods used displayed similar behavior and provided a tentative addition close to the final addition. The coefficient of agreements (COA) detected suggests that every tentative addition should be adjusted according to the particular needs of the patient.
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Arq Bras Oftalmol. 2013;76(4):218-20
Artigo Original | Original article
INTRODUCTION
Presbyopia (from the Greek presbys, elder or old, and, -ops, eye)
is a progressive condition where the ability to focus on near objects
is gradually lost as part of the natural aging process
(1)
. Presbyopia
tends to manifest itself around the age of 40 to 45 years, at an ex-
tremely productive stage in life and its inadequate correction will
compromise a persons work performance with the economic loses
that this entails
(2)
.
The optical correction of presbyopia must be handled indivi-
dually. The amount of accommodation varies not only from person to
person, but also from eye to eye. Therefore it is necessary to prescribe
the weakest lenses which are tolerable for good and comfortable
near vision in order to find harmony between the processes of ac-
commodation and convergence
(3)
. Normally, a tentative addition is
established first and this is then adjusted to obtain the final addition
(4)
.
In the case of correction it is necessary to respect working distance to
which a person has to adapt their vision and which is very important
in various professions. An error in reading addition is one of the most
common causes of patients’ unhappiness with their new spectacles
(5)
.
For example, when the range of clear vision is not well determined,
patients may complain that the new spectacles are fine for reading,
but that they are now unable to see a computer screen
(6)
. A classic
clinical rule, used by most ophthalmologists, is that the patient
should be able to support up to half of its full range of amplitude of
ac commodation (AA)
(7)
.
Many variables affecting accommodative testing are difficult to
control, including illumination, depth of focus, target size, contrast,
visual angle, lens affectiveness, monocular and binocular cues, kines-
An evaluation of estimation methods for determining addition in presbyopes
Avaliação de diferentes métodos para determinar adição em présbitas
Leonardo Catunda BittenCourt
1
, MiLton ruiz aLves
2
, danieL oLiveira dantas
3
, PaBLo FeLiPe rodrigues
4
, edson dos santos-neto
5
Submitted for publication: August 21, 2012
Accepted for publication: May 21, 2013
Study carried out at Hospital das Clínicas da Faculdade de Medicina, Universidade de São Paulo -
USP - São Paulo (SP), Brazil.
1
Physician, Hospital das Clínicas da Faculdade de Medicina, Universidade de São Paulo - USP - São
Paulo (SP), Brazil.
2
Physician, Setor de Córnea e Doenças Externas do Hospital das Clínicas da Faculdade de Medicina,
Universidade de São Paulo - USP - São Paulo (SP), Brazil.
3
Statistician, São Paulo (SP), Brazil.
4
Physician, Setor de Córnea e Doenças Externas no Hospital das Clínicas da Faculdade de Medicina,
Universidade de São Paulo - USP - São Paulo (SP), Brazil.
5
Physician, Hospital das Clínicas da Faculdade de Medicina, Universidade de São Paulo - USP - São
Paulo (SP), Brazil.
Funding: No specific financial support was available for this study.
Disclosure of potential conflicts of interest: L.C.Bittencourt, None; M.R.Alves, None; D.O.Dantas,
None; P.F.Rodrigues, None; E.Santos-Neto, None.
Correspondence address: Leonardo Catunda Bittencourt. Rua Loefgren, 441 - Apto. 153 - São
Paulo (SP) - 04040-030 – Brazil - E-mail: leocatunda@gmail.com
Número do projeto no comitê de ética: 0821/10 HCFMUSP.
ABSTRACT
Purpose: The optical correction of presbyopia must be handled individually. Our
aim was to compare the methods used in addition to the refractive near vision,
with the final addition used in presbyopic patients.
Methods: Eighty healthy subjects with a mean age of 49.7 years (range 40 to 60
years) were studied. Tentative near additions were determined using four diffe-
rent techniques: one-half amplitude accommodation with minus lenses (AAL);
one-third accommodative demand with positive lens (ADL); balanced range of
accommodation with minus and positive lenses (BRA) and crossed cylinder test
with initial myopisation (CCT). The power of the addition was then refined to
ar rive at the final addition.
Results: The mean tentative near additions were lower than the final addition
for ADL and BRA addition methods. The mean differences between tentative and
final additions were low for all the tests examined (less than 0.25 D). The intervals
between the 95% limits of agreement differed substantially and were always higher
than ±0.50 D.
Conclusion: All the methods used displayed similar behavior and provided a
tentative addition close to the final addition. The coefficient of agreements (COA)
detected suggests that every tentative addition should be adjusted according to
the particular needs of the patient.
Keywords: Accommodation, ocular; Eyeglasses; Presbyopia/therapy; Depth per -
ception; Lenses
RESUMO
Objetivo: A correção óptica da presbiopia deve ser manejada individualmente. Nosso
intuito é de comparar os métodos usados para calcular a adição na elaboração do
grau para perto em pacientes présbitas.
Métodos: Oitenta pacientes com média de idade de 49,7 anos (intervalo de 40 a
60 anos) foram estudados. Adições provisórias foram determinadas usando quatro
diferentes técnicas: metade da amplitude de acomodação com lentes negativas
(AAL); um terço da demanda acomodativa com lentes positivas (ADL); média arit -
mética da acomodação usando lentes positivas e negativas (BRA); teste com o
cilindro cruzado com miopização (CCT). O grau final foi refinado até chegar a
gra duação final da adição.
Resultados: A média das adições nos testes foram menores que as adições finais nos
métodos ADL e BRA. As diferenças médias entre os testes e o grau final foram baixas
em todos os métodos (menores que +0,25 D). Os intervalos entre os 95% dos limites
da concordância diferenciaram substancialmente e foram todos maiores que ±0.50 D.
Conclusão: Todos os métodos usados demonstraram comportamentos similares e
forneceram resultados bem próximos da adição final. O coeficiente de concordância
(COA) detectado, sugere que todos os métodos utilizados devem ser ajustados de
acordo com as necessidades do paciente.
Descritores: Acomodação ocular; Óculos; Presbiopia/terapia; Percepcão de profun-
didade; Lentes
Bittencourt LC, et al.
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Arq Bras Oftalmol. 2013;76(4):218-20
thetic feedback, and the rate at which accommodative demand is
changed during testing
(8)
. We feel it would be more reasonable to use
the method that provides the tentative addition closest to the final
addition. It is felt that it would accelerate the entire evaluation pro-
cess. This study was designed to compare final addition values with
the tentative additions obtained using the tests: one-half amplitude
accommodation with minus lenses (AAL); one-third accommodative
demand with positive lens (ADL); balanced range of accommodation
with minus and positive lenses (BRA) and crossed cylinder test with
initial myopisation (CCT).
METHODS
An observational, cross-section study was carried out. The re-
search followed the tenets of the Declaration of Helsinki, and Insti-
tutional Review Board approval was obtained. All patients were
in formed about the purpose of the study and gave informed consent
before inclusion. Patients were sequentially evaluated from February
to November 2011. The age range of the subjects was 40 to 60 years
(mean: 49.7, standard deviation: ± 5.0 years). Fifty (62.5%) patients
were women and thirty (37.5%) were men. The spherical refractive
error ranged from -5.75 to +5.00 D with up to -1.50 D of astigmatism.
All patients required addition; and presented corrected mono-
cular visual acuity (VA) greater than or equal to 6/7.5 at distance and
near; anisometropy less than 1.50 D; no binocular problems; no history
of refractive surgery, strabismus or amblyopia; no ocular pathology;
no systemic disease that could affect accommodation, fusional
vergences and/or ocular motility; and no medication likely to have
side effects on accommodation and/or on fusional vergences. All the
patients were submitted to the four different methods.
Demographic and clinical data were obtained, including data
of birth and gender. Each subject underwent a comprehensive oph -
thalmologic examination including review of medical history, sub -
jective refraction followed by binocular balancing, with Snellen
op totypes presented at 6 meters, best correct visual acuity, slit-lamp
biomicroscopy, ocular tonometry and fundoscopic examination.
The subjective refractions were conducted to maximize the amount
of positive sphere and minimize the amount of negative sphere
without compromising distance visual acuity. Astigmatism was ad-
justed using the Jackson cross-cylinder. All the procedures used to
determine tentative addition were performed in random order. The
final addition for a 40 cm working distance was established for each
patient by adjusting the tentative addition (AdT) obtained using one
to the four methods selected at random:
AAL Method - one-hALf AMpLitude AccoMModAtion (AA)
with Minus Lenses
This procedure assumes that the prescription of addition should
not use more than one-half of the total amplitude, the working
distance in this study was 40 cm, so the tentative addition value was
calculated as 2.50 D -1/2(AA), where AA is the mean amplitude of
accommodation between both eyes. To measure the AA, the sub-
ject was instructed to read the fine print on the nearpoint test card,
placed at 40 cm, while the accommodative demand was increased
using minus lens in 0.25 D steps by making a conscious accommo-
dative effort.
AdL Method - one-third AccoMModAtive deMAnd (Ad)
with positive Lens
To measure the AD, with distance refraction in the phoropter
and the nearpoint test card at 40 cm, the subject was instructed to
read the fine print on the test card. Then, plus lenses in 0.25 steps
were added until the fine print on test card become clear (L), so the
AD was calculated as 2.50 D - L, and the tentative addition value was
calculated as 1/3AD + L.
BrA Method - BALAnced rAnge of AccoMModAtion
with Minus And positive Lenses
This procedure assumes that the prescription of addition is to
place the dioptric midpoint of the range of clear vision at the patients
customary near working distance. The dioptric midpoint was deter-
mined, with the patient’s distance refraction in the phoropter and the
near point test card at 40 cm, by adding plus power lenses binocularly
until the subject was no longer able to read the fine print on the test
card, and by adding minus power lenses until the patient was no
longer able to read the fine print, so the tentative addition value was
calculated as the arithmetical media of these values.
cct Method - crossed cyLinder test with initiAL MyopisAtion
A cross-grid target was placed on the near point rod of the pho-
ropter at the patient’s working distance, in this study at a 40 cm, and
the crossed cylinder (with the minus axis vertical) was positioned
before both eyes. With the distance correction in place, were added
plus lenses until the vertical lines on the target become as clear and
dark as the horizontal lines, this was the tentative addition value.
The data were analyzed using the Analyze-it program for Micro soft
Excel (Leeds, UK. See http://www.analyse-it.com statistics pro gram)
(6)
.
The level of agreement between the different tentative ad dition tests
and the prescribed addition, or reference addition, was estimated using
the Bland-Altman method
(9,10)
. Correlation is nor mally used to evaluate
the agreement between two methods. The problem of correlation is that
it is high when the points of the scatter plot fall on any straight line with
positive derivative
(6)
. The factors determined were the mean difference
(Bias), the standard deviation (SD), the coeffi cient of agreement (COA=
1.96 x SD) and the limits of agreement at the 95% level (Bias ± COA). The
t-test for paired samples was also used to establish the significance of the
differences. The level of significance was set at p<0.05.
RESULTS
Table 1 provides data on the level of agreement between each
of the tests used to determine tentative addition in presbyopes and
the final addition. The mean differences between tentative and final
additions were low (less than 0.25 D) and the coefficients of agreement
are moderately high in clinical terms, as they always exceeded 0.50 D.
Figure 1 shows plots for each subject of the difference between
the tentative addition (AdT) and the final addition (AdF) versus the
mean of the two additions. The lines at U and L, respectively, show
the upper and the lower 95% limits of agreement. The same scales
are used in all figures to aid the visual comparison of biases and
agreement intervals.
DISCUSSION
The evaluation and management of presbyopia are important
be cause significant functional deficits can occur when the con-
dition is left untreated. Undercorrected or uncorrected presbyopia
can cause significant visual disability and have a negative impact
on the patient’s quality of life
(3)
. Careful distance refraction provides
the foundation for determining the management of presbyopia
(3)
.
The optical correction for presbyopia is the sum of the refractive
cor rection for distance plus the power of the near addition
(3)
. The
nature of the distance correction itself influences the near addition
(11)
.
Determining the addition in the presbyope is an essential clinical
test for evaluating patients over the age of 40 years
(7)
. The results of
these tests are usually refined according to the subject’s preference
in terms of image clarity and a comfortable near task distance
(12)
. The
refinement stage will be shorter and easier if the tentative addition is
determined as precisely as possible
(6)
.
In this study, the aim was to establish the level of agreement bet-
ween tentative additions determined by four methods and the final
addition. The results indicate that the mean differences between ten-
An evaluation of estimation methods for determining addition in presbyopes
220
Arq Bras Oftalmol. 2013;76(4):218-20
tative and final additions were low for all the tests examined (less than
0.25 D). The agreement intervals ranged from about ± 0.50 D to ± 0.75 D
(Table 1 and Figure 1). This means that the tentative addition provided
by the AAL and ADL methods could be up to 0.75 D higher or lower
than the final addition prescribed to the patient. Likewise the tentative
addition provided by BRA and CCT methods could be up to 0.50 D
higher or lower than the final addition prescribed for the patient. The
ADL based addition underestimated the addition (p=0.0003). Likewise,
the BRA based addition underestimated the addition (p=0.008).
The different methods used to determine tentative addition
based on objective or subjective tests are not very reliable. Besides
that, characteristics of the patient, such as visual needs, work habits,
previous prescriptions may contribute to the different results, and
consequently the wide COA obtained.
Antona et al.
(6)
compared final addition values with the tentative
additions obtained using dynamic retinoscopy, amplitude of accom -
modation, age expected addition, fused cross cylinder without initial
myopisation, fused cross cylinder with initial myopisation, near duo-
chrome and the negative relative accommodation/positive relative
accommodation (NRA/PRA) balance. For these authors the method
that provided the result closest to the final addition power was the
age-expected AA procedure. For them this test showed the narro-
west agreement interval and the least bias.
As a result of this study the choice of method will be affected
because all tests were similar in accuracy for the tentative addition,
in other aspects, such as ease of application and time taken, the
age expected addition method for assessing the tentative addition
is an easy and effective test and it takes no time. A table of age-ex-
pected accommodative amplitudes can serve as a starting point for
determining a near addition
(13-15)
. However, the values in the tables
represent population averages, and the measured amplitude of ac-
commodation for the individual patient may differ significantly from
the age-group average. Measuring the amplitude of accommodation
provides a more appropriate indication of the patient’s accommoda-
tive ability and range of clear vision
(3)
.
These findings suggest that all the studied techniques displayed
similar behavior and provided a tentative addition close to the final
addition. Finally, the wide agreements detected here suggest that
every tentative addition should be adjusted according to the parti-
cular needs of the patient.
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Table 1. Agreement between tentative and nal addition
Mean BIAS p value COA
AAL 1.925 -0.003 (AAL>AdF) 0.9400 ± 0.725
ADL 1.803 -0.100 (ADL<AdF) 0.0003 ± 0.700
BRA 1.784 -0.100 (BRA<AdF) 0.0008 ± 0.550
CCT 1.941 -0.019 (CCT>AdF) 0.5705 ± 0.577
AdF= final addition; COA= coefficient of agreement (1.96 x standard deviation); Tentative
add: AAL= one-half amplitude accommodation (AA) with minus lenses; ADL= one-third
accommodative demand with positive lens; BRA= balanced range of accommodation
with minus and positive lenses; CCT= crossed cylinder test with initial myopisation.
Figure 1. Plots for each subject of the dierence between the tentative addition and
the nal addition (AdF- AdT) against the mean of both. The lines at U and L, respectively,
indicate the upper and lower 95% limits of agreement.
... Bittencourt et al. 16 compared the adds derived from four tests to the final add used in 80 patients with presbyopia. The patients ranged in age from 40 to 60 years (mean age 50 years). ...
... The authors suggested that the procedures they studied on average "provided a tentative addition close to the final addition," but like Antona et al., 12 they noted that the "addition should be adjusted according to the particular needs of the patient." 16 ...
... A variable in basing an add on keeping some percentage of the amplitude in reserve is whether amplitude is determined from pushup, push-away, or minus lens procedure. The keep half the amplitude in reserve guideline averaged 0.04 D less plus (COA, 0.75 D) than the preferred add in the Ray 10 study, and 0.003 D more plus (COA, 0.73 D) than the final add in the Bittencourt et al. 16 study. ...
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... Therefore it is necessary to provide the weakest and most proper addition measured for each eye separately, in order to establish a correlation between accommodation and convergence. [6] Patient's habitual working distance is a fundamental factor to determine a precise and suitable correction. According to a classic rule for optical correction of presbyopia, patients should use up to half of their amplitude of accommodation. ...
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Purpose: To compare three different methods for determining addition in presbyopes. Methods: The study included 81 subjects with presbyopia who aged 40-70 years. Reading addition values were measured using 3 approaches including the amplitude of accommodation (AA), dynamic retinoscopy (DR), and increasing plus lens (IPL). Results: IPL overestimated reading addition relative to other methods. Mean near addition obtained by AA, DR and IPL were 1.31, 1.68 and 1.77, respectively. Our results showed that IPL method could provide 20/20 vision at near in the majority of presbyopic subjects (63.4%). Conclusion: The results were approximately the same for 3 methods and provided comparable final addition; however, mean near additions were higher with increasing plus lens compared with the other two methods. In presbyopic individuals, increasing plus lens is recommended as the least time-consuming method with the range of ±0.50 diopter at the 40 cm working distance.
... 3 Patient's habitual working distance is crucial to determine the most suitable correction. 4 Not everyone will accept lens powers given randomly or approximately, based on age. 1 A person with myopia (short-sightedness) many a time might require less presbyopia correction or may compromise removing their distance correction to see close. They should remove their distance spectacles if he wants to see at a close distance. ...
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Introduction: Presbyopia is a progressive condition where the ability to focus on near objects is gradually lost as part of the natural aging process. Similarly, hearing loss is the most widespread sensory impairment in aging people. Thus, the present study was conducted to study the demographic profile of patients with presbyopia and presbycusis. Material and methods: The Study was conducted on 60 patients reporting to the Eye OPD of Regional Eye institute, Amritsar. Examination of total 120 eyes and 120 ears were conducted to evaluate presbyopia and presbycusis. To check the status of vascular system the investigations done were blood pressure, haemoglobin, total leucocytes count, differential leucocytes count, fasting blood sugar, lipid profile, ECG and urine complete examination. Obtained data was arranged according to characteristics and was expressed as a number and percentage of respondents and were analyzed using the SPSS Version 17 software. Results: Females dominated among the cases of presbyopia while males were dominated among the cases having presbycusis. Maximum cases of presbyopia were seen in service class while no significant difference in hearing was observed among cases in various occupations. No significant difference in near vision and hearing was observed in smokers and alcoholics. Conclusion: Both the condition of presbyopia and presbycusis increased gradually with the age but no relationship was found between arterial hypertension, blood sugar level, serum cholesterol level and consumption of tobacco and alcohol. No significant difference in hearing was observed among cases in various occupations.
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C.V. Mosby Company; St. Louis 1985, pp654, Third Edition ($135.45: Review Copy courtesy of CIG Medishield)
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Methods of analysis used in the comparison of two methods of measurement are reviewed. The use of correlation, regression and the difference between means is criticized. A simple parametric approach is proposed based on analysis of variance and simple graphical methods.
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In clinical measurement comparison of a new measurement technique with an established one is often needed to see whether they agree sufficiently for the new to replace the old. Such investigations are often analysed inappropriately, notably by using correlation coefficients. The use of correlation is misleading. An alternative approach, based on graphical techniques and simple calculations, is described, together with the relation between this analysis and the assessment of repeatability.
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One method of determining the additional correction for presbyopia suggests leaving a percentage of the amplitude of accommodation in reserve. The rationale for this assumption seems logical because using all of the available accommodation is not sustainable without discomfort. However there is no empirical evidence indicating what percentage of the amplitude of accommodation should actually be left in reserve. Common figures adopted have been one-half and one-third. In this investigation the percentage of accommodation used is deduced mathematically after having determined the following: 1. The ‘add’ by the direct subjective clinical method. 2. Measured the amplitude of accommodation. 3. Measured the reading distance in 305 presbyopes ranging from 40 to 83 years of age. The results showed a small decline in the amplitude of accommodation up to the age of 52, after which age the measurements were scattered about a steady level. This finding suggests that after the age of 52 the results are based on the depth-of-focus of the eye. Females had slightly greater accommodation than males of the same age. The power of the add was significantly correlated to the age of the subject. The mean percentage of accommodation used for the 305 subjects was found to be 50.7%, thus confirming the rule of leaving half of the accommodation in reserve, although there were large variations: there were differences between males and females and with age the percentage of measured accommodation used, after having determined the correct add, diminished. Similarly the percentage of accommodation also decreased for shorter reading distances.
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Presbyopia, fresbyopia—who cares! Look up Donders' table, if you have not already memorized it, and give them reading glasses. "It's old age creeping up on you, Mr Jones. Welcome to the club! Here's your prescription. There's nothing else we can do about it." Well, maybe there isn't. But how can we know that when some textbooks still attribute presbyopia to some unknown entity of "lenticular sclerosis" and the word "presbyopia" is conspicuous in subject indexes of research journals only by its absence? This issue of the Archives represents a rare exception, containing a highly relevant article by Lutjen-Drecoll and colleagues1 on aging changes in ciliary muscle structure and responsiveness. See also p 1591. Before we address the implications of this contribution, we must briefly consider some assumptions that may account for the remarkable lack of research on the seemingly unique vulnerability of our accommodative mechanism to aging. The reader
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From a previous study at the Optometric Center of Fullerton, it was found that 17.5% of the review clinic population returned due to improper presbyopic reading adds. The population sample for the present study consisted of patients between 40-60 years of age who returned to the clinic between September 1983 and May 1985 due to improper add power. The add power originally prescribed was compared to each of four commonly used methods of add power determination. Our results indicate that the age expected add powers account for the fewest errors while the binocular cross cylinder the most. Upper and lower limits for an acceptable range of add powers versus age were determined.