elise harb, sanbrita ghosh, kristen totonelly, mark o...
TRANSCRIPT
PrimateChair
IR HotMirror
Video Monitor
MoveableStimulus
Line of Sight to Stimulus
PowerRefractor
The Accommodation Response in Marmosets withImposed Anisometropia
Elise Harb, Sanbrita Ghosh, Kristen Totonelly, Mark O’Connor, David TroiloNew England College of Optometry, Boston, MA 02115
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Refraction (pl lens)Refraction (+3D lens)
Time (s)
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Refraction (-3D lens)Refraction (+3D lens)
Refraction
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Stimulus PositionRefraction (pl lens)Refraction (-3D lens)
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Inmrot
Introduction
Purpose
Methods
Results Summary and Conclusions
E. Harb Commercial Relationships: NoneSupported by NEI-EY 011228
• Imposing anisometropia in marmosets with monocularcontact lenses or binocular contact lenses of oppositesign results in un-yoked compensatory changes in axialgrowth and refractive state (Troilo et al., 2007).
• In general, the accommodative behavior underanisometropic conditions is open to speculation.Flitcroft (1992) suggested that the accommodativedemand between the two eyes was averaged toproduce a consensual accommodative response.Hung (1995) hypothesized that the eye with the lessdemand was used to drive the accommodative response.
• In this study we attempt to describe the binocularaccommodative response with lens imposedanisometropia in order to fully understand the effectiverefractive state experienced during such lens wear.
untreated controlmonocular positive lensmonocular negative lensbinocular lenses of opposite sign
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Ref
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Err
or(D
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Juvenile marmosets wearingsoft contact lenses.
• We measured binocular accommodation in three untreated marmosets(ref. error range: +0.75 to -1.30) binocularly fit with custom made softcontact lenses to produce three anisometropic conditions;(1) pl/+3, (2) pl/-3,(3) +3/-3. The lenses were worn for only the period of time needed to measureaccommodative function (approx 30 min).
•The binocular accommodative response was measured through each ofthe anisometropic conditions and with no lenses with an IR videorefractor(PowerRefractor, MultiChannel Systems) on multiple occasions atvarying accommodative stimuli positions.
• Visual stimuli consisted of video images displayed at varyingdistances (between 0.50 and 0.13 m) from a primate chair. ThePowerRefractor was used to monitor eye position andrefractive state continuously (Schaeffel et al.,1993).
• Accommodative stimulus demands were calculated from the targetdistance, subjects’ cycloplegic refraction (measured on another day)and lens power worn.
• Under lens imposed anisometropia, it appearsthat the accommodative demand of each eye isproviding input into the accommodativeresponse, potentially by an averagingmechanism.
• It appears that the presence of a negative lensdecreases the accommodative response of thecontralateral eye, potentially by increasing theaverage accommodative demand of the two eyes.
• In general, the accommodative errorsexperienced by each eye under the threeanisometropic lens conditions result in retinaldefocus conditions that predict the compensatorygrowth patterns observed in marmosets, asdescribed earlier (Troilo et al., 2007);
· pl/+3: +3 eye experiences more myopicdefocus and becomes relatively more hyperopic
· pl/-3: -3 eye experiences more hyperopicdefocus and becomes relatively more myopic
· +3/-3: -3 eye experiences more hyperopicdefocus and becomes relatively more myopic.
• Two subjects measured with no lenses in place demonstrated appropriate shifts in refractivestate for changing stimulus positions, as shown by the stimulus-response functions below.
• Examples of accommodative changes under lens-imposed anisometropic conditions,suggest that the relatively more myopic eye was better focused to the stimulus.
• The difference in the effective refractive statebetween the two eyes differed consistentlybetween lens conditions at all stimulus positions.
• Although the imposed anisometropic conditionscreated expected differences in accommodativedemand between the two eyes, the mean differencein the response was always less than the demanddifference when a negative lens was worn.
• Examples of the refractions at the 6D stimulusdistance suggest that the presence of a negative lensproduces a reduced accommodative response in thecontralateral eye suggesting that the accommodativedemands are averaged between the two eyes in theseconditions.
References
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OD Mean Refractive StateOS Mean Refractive State
y = 0.18 + 0.91x R= 0.95
y = -0.86 + 0.73x R= 0.8
Mea
nR
efra
ctiv
eS
tate
(D)
Stimulus Position (D)
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-1-9-8-7-6-5-4-3-2-1
OD Mean Refractive StateOS Mean Refractive State
y = 0.18 + 0.91x R= 0.95
y = -0.86 + 0.73x R= 0.8
Mea
nR
efra
ctiv
eS
tate
(D)
Stimulus Position (D)
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-1
0
1
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3-7.670-6.020-4.000-3.030-2.000
(pl eye) - (+3eye); p=0.97(pl eye)- (-3 eye); p=0.87(+3 eye) -(-3 eye); p=0.98
Diff
eren
cein
Effe
ctiv
eR
efra
ctiv
eS
tate
(D)
Stimulus Position (D)
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6-8-6-4-20246
(pl eye) - (+3eye)(pl eye)- (-3 eye)(+3 eye) -(-3 eye)
Inte
rocu
larD
iffer
ence
inE
ffect
ive
Ref
ract
ive
Sta
te(D
)
Interocular Difference in Accommodative Demand (D)
mean 2.42D
mean -1.26D
mean -3.06D
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2Pl +3D Pl -3D +3D -3D
Mea
nE
ffect
ive
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ract
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te(D
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Anisometropic Lens Condition
/ / /
-6D Stimulus
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ous
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Flitcroft, D. I., Judge, S. J., & Morley, J. W. (1992) Binocular interac-tions in accommodation control: Effects of anisometropic stimuli.Journal of Neuroscience, 12(1), 188-203.
Hung, L., Crawford, M. L. J., & Smith, E. L. (1995) Spectacle lensesalter eye growth and the refractive status of young monkeys. NatureMedicine, 1(8), 761-765.
Schaeffel, F., Howland, H., Weiss, S. & Zrenner, E. (1993) Measure-ment of the dynamics of accommodation by automated real timephotorefraction. Invest. Ophthalmol. Vis. Sci. (ARVO Suppl.)34:1306.
Troilo,D., Totnelly, K., Kee, C-S., & Nickla,D. (2007) Aniso conatctlens rearing induces anisometroipa in marmosets. Invest. Ophthalmol.Vis. Sci. (ARVO Suppl.) 48:1032.
Parental history of MyoPia in Chinese MyoPiC Children
1 institute for eye research, sydney australia; 2 Vision CrC, sydney, australia and 3 Zhongshan opthalmic Centre, Guanzhou, China
Percy lazon de la Jara1,2, les donovan1,2, Padmaja r. sankaridurg1,2, thomas naduvilath2, aldo Martinez1,2, arthur ho1,2, Xiang Chen2,3, Julia Chen3, Jian Ge3, Brien holden1,2
PUrPose
resUlts
Methods statistiCal analysis
To assess the relationship between parental myopia, the refractive state and ocular biometry of Chinese myopic children.
210 myopic children (mean age of 11 ± 2.3 years, range 6-16 years) were recruited for a longitudinal QQ
myopia progression study at the Zhongshan Ophthalmic Centre, Guangzhou, China. At baseline, refractive error and axial length were determined on cyclopleged eyes using an open QQ
field auto-refractor (NVision-K 5001, Shin Nippon, Japan) and an interferometer (IOLMaster, Carl Zeiss Meditec, Germany). Data on parental myopia was collected using a survey completed by parents. QQ
Data from the two eyes were averaged QQ
prior to data analysis. Statistical association of spherical QQ
equivalent (SE) and axial length (AL) with parental history of myopia was investigated using correlations and linear mixed models.
ConClUsion
referenCes
Similar to previous studies reporting an association of myopia in children with parental myopia QQ
[1-3], spherical equivalent refractive error of children with two myopic parents was more myopic than those with one or no myopic parent.In contrast to previous reports [2], we did not find an association of axial length and parental myopia. QQ
The mean axial length of children with two or one myopic parent was shorter than myopic children with no myopic parents. Similar results have been reported in pre-myopic Chinese children [4].The weak correlation between spherical equivalent and axial length suggests that factors other QQ
than axial length (i.e. the crystalline lens [5-7]) could be contributing to this variance in spherical equivalent refractive power and needs to be explored further.
disClosUre - none
1. Hirsch, M.J. and D.L. Ditmars, Refraction of young myopes and their parents--a reanalysis. Am J Optom Arch Am Acad Optom, 1969. 46(1): p. 30-2.
2. Zadnik, K., et al., The effect of parental history of myopia on children’s eye size. Jama, 1994. 271(17): p. 1323-7.3. Gwiazda, J., et al., Emmetropization and the progression of manifest refraction in children followed from infancy to
puberty. Clin Vis Sci, 1993(8): p. 337-44.4. Lam, D.S., et al., The effect of parental history of myopia on children’s eye size and growth: results of a longitudinal
study. Invest Ophthalmol Vis Sci, 2008. 49(3): p. 873-6.5. Mutti, D.O., et al., Optical and structural development of the crystalline lens in childhood. Invest Ophthalmol Vis Sci,
1998. 39(1): p. 120-33.6. Zadnik, K., et al., Ocular component data in schoolchildren as a function of age and gender. Optom Vis Sci, 2003.
80(3): p. 226-36.7. Zadnik, K., et al., Longitudinal evidence of crystalline lens thinning in children. Invest Ophthalmol Vis Sci, 1995.
36(8): p. 1581-7.
Of the 210 myopic children, 40 had two myopic parents (19%), 90 had one myopic parent (43%) and 80 had no myopic parents (38%).QQ
At baseline, the mean SE was -1.88 ± 0.64D (range -0.75 to -3.75D) and the mean AL was 24.5±0.7mm (range 23.0 to 27.8mm)QQ
SPHERICAL EQUIVALENT AND PARENTAL MYOPIAThere was an association between SE and parental myopia (p<0.05). Children with two
myopic parents had greater myopia compared to those with no myopic parents (p=0.018).
AXIAL LENGTH AND PARENTAL MYOPIAInterestingly, there was no association between parental myopia and AL.
SPHERICAL EQUIVALENT AND AXIAL LENGTHWhen SE and AL were considered, it appears that there was only a weak correlation with AL after
adjustment for age (r=-0.33, p<0.001)
The multivariate analysis, after adjusting for gender, years of spectacle usage, hours per week reading books and baseline AL, showed that the mean spherical equivalent increased
by -0.15D per myopic parent (p=0.007).
Figure 1. Baseline cycloplegic refraction based on the average spherical equivalent of two eyes.
Figure 4. Parental myopia and AL on their offspring
Figure 5. Pearson correlation between SE and AL.
Figure 2. Baseline axial length based on the average of two eyes.
Figure 3. Parental myopia and level of myopia in their offspring.
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f Eye
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-1.68-2.01-1.88
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# of Myopic Parents
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** p=0.018
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f Eye
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24.4324.4424.51
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24.60
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# of Myopic Parents
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al L
engt
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Age adjusted r = -0.33
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