The Effect of Simultaneous Negative and Positive Defocus on Eye Growth and Development of Refractive State in Marmosets

SUNY College of Optometry, New York, New York.
Investigative ophthalmology & visual science (Impact Factor: 3.4). 08/2012; 53(10):6479-87. DOI: 10.1167/iovs.12-9822
Source: PubMed


We evaluated the effect of imposing negative and positive defocus simultaneously on the eye growth and refractive state of the common marmoset, a New World primate that compensates for either negative and positive defocus when they are imposed individually.

Ten marmosets were reared with multizone contact lenses of alternating powers (-5 diopters [D]/+5 D), 50:50 ratio for average pupil of 2.80 mm over the right eye (experimental) and plano over the fellow eye (control) from 10 to 12 weeks. The effects on refraction (mean spherical equivalent [MSE]) and vitreous chamber depth (VC) were measured and compared to untreated, and -5 D and +5 D single vision contact lens-reared marmosets.

Over the course of the treatment, pupil diameters ranged from 2.26 to 2.76 mm, leading to 1.5 times greater exposure to negative than positive power zones. Despite this, at different intervals during treatment, treated eyes were on average relatively more hyperopic and smaller than controls (experimental-control [exp-con] mean MSE ± SE +1.44 ± 0.45 D, mean VC ± SE -0.05 ± 0.02 mm) and the effects were similar to those in marmosets raised on +5 D single vision contact lenses (exp-con mean MSE ± SE +1.62 ± 0.44 D. mean VC ± SE -0.06 ± 0.03 mm). Six weeks into treatment, the interocular growth rates in multizone animals were already lower than in -5 D-treated animals (multizone -1.0 ± 0.1 μm/day, -5 D +2.1 ± 0.9 μm/day) and did not change significantly throughout treatment.

Imposing hyperopic and myopic defocus simultaneously using concentric contact lenses resulted in relatively smaller and less myopic eyes, despite treated eyes being exposed to a greater percentage of negative defocus. Exposing the retina to combined dioptric powers with multifocal lenses that include positive defocus might be an effective treatment to control myopia development or progression.

Download full-text


Available from: David Troilo, Jun 20, 2014
  • Source
    • "Improvements in accommodation performance, i.e., reduced lags, have also been reported with orthokeratology [31], lending further support to the notion that reduction or elimination of accommodative lags contributes to the myopia control effects of such treatments. The notion that the peripheral retina plays a critical role in refractive error development and thus in myopia progression also has its origins in animal model studies [32] [33] [34] [35] [36] and is driving the development of some novel designs of spectacles [7] [8] and soft contact lenses (SCLs) [9] [10] [11] for myopia control. The underlying premise is that by manipulating the defocus experience of the peripheral retina, one can either neutralise the optical defocus stimulus for excessive axial length elongation, i.e., by correcting peripheral (off-axis) hyperopia, or reverse it by imposing myopic defocus, thereby inhibiting eye growth. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: To characterise the effects on accommodation and binocular vision in young adults of 2 distance centre multifocal soft contact lenses (MFSCLs), differing in add power. Methods: Twenty-four young adult myopes (18-28 years; 20 females, 4 males) had baseline visual acuity, accommodation, near phoria, fixation disparity and stereopsis data collected with single vision (SV) SCLs. The same set of measurements was repeated immediately after subjects were fitted with each of two MFSCLs (with either +1.50 or +3.00 D add), and after 2 weeks of daily wear in each case. The order of testing was randomised and a one-week washout period was allowed between the first and second MFSCL trials. Results: Differences in distance and near acuities with MFSCLs compared to SVSCLs were small and clinically insignificant. Compared to responses with SVSCLs, MFSCLs increased accommodative lags with this change reaching statistical significance for the +1.50 D add lens. Furthermore, both MFSCLs induced significant shifts in near phorias in the exo direction. Finally, there were no significant differences in stereopsis and fixation disparity with MFSCLs compared to SVSCLs. Conclusion: Differences in acuities, accommodation accuracy and binocular posture with MFSCLs compared to SVSCLs were clinically small and mostly not significant. These results predict good tolerance of MFSCLs in young patients fitted with them for myopia control.
    Contact lens & anterior eye: the journal of the British Contact Lens Association 10/2015; DOI:10.1016/j.clae.2015.09.004 · 1.37 Impact Factor
  • Source
    • "In particular , experiments in monkeys have indicated that visual signals from the peripheral retina are essential for several aspects of regulation of vision-dependent ocular growth [4]. Moreover, recent studies have shown that inducing a multifocal image on the eye and moving the image forward at the peripheral retina, leaving it myopically defocused, generates a visual stimulus to slow ocular growth [5] [6]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Objective. To evaluate the degree of axial elongation with soft radial refractive gradient (SRRG) contact lenses, orthokeratology (OK), and single vision (SV) spectacle lenses (control) during a period of 1 year before treatment and 2 years after treatment. Methods. This was a prospective, longitudinal, nonrandomized study. The study groups consisted of 30, 29, and 41 children, respectively. The axial length (AL) was measured during 2 years after recruitment and lens fitting. Results. The baseline refractive sphere was correlated significantly (Spearman's Rho (í µí¼Œ) correlation = 0.542; P < 0.0001) with the amount of myopia progression before baseline. After 2 years, the mean myopia progression values for the SRRG, OK, and SV groups were −0.56 ± 0.51, −0.32 ± 0.53, and −0.98 ± 0.58 diopter, respectively. The results represent reductions in myopic progression of 43% and 67% for the SRRG and OK groups, respectively, compared to the SV group. The AL increased 27% and 38% less in the SRRG and OK groups, respectively compared with the SV group at the 2-year visit (P < 0.05). Axial elongation was not significantly different between SRRG and OK (P = 0.430). Conclusion. The SRRG lens significantly decreased AL elongation compared to the SV control group. The SRRG lens was similarly effective to OK in preventing myopia progression in myopic children and adolescent.
    BioMed Research International 10/2015; 2015(2015):10. DOI:10.1155/2015/507572 · 2.71 Impact Factor
  • Source
    • "To relieve this spasm, the fogging method [9] and the dilating drops like atropine have been widely used and it was reported to have substantial effects with non-accomodative mechanism as observed in chick-eye experiment reported by McBrien et al. [18,19]. Others included electrostimulation [19] and multifocal contact lens [20-25]. In addition, 3D image stimulator which was approved as a medical device has been used in our clinics for purposes such as relaxing the over-tensed muscle [26,27]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate the efficacy of two non-surgical interventions of vision improvement in children. A prospective, randomized, pilot study to compare fogging method and the use of head mounted 3D display. Subjects were children, between 5 to 15 years old, with normal best corrected visual acuity (BCVA) and up to -3D myopia. Subjects played a video game as near point work, and received one of the two methods of treatments. Measurements of uncorrected far visual acuity (UCVA), refraction with autorefractometer, and subjective accommodative amplitude were taken 3 times, at the baseline, after the near work, and after the treatment. Both methods applied after near work, improved UCVA. Head mounted 3D display group showed significant improvement in UCVA and resulted in better UCVA than baseline. Fogging group showed improvement in subjective accommodative amplitude. While 3D display group did not show change in the refraction, fogging group's myopic refraction showed significant increase indicating the eyes showed myopic change of eyes after near work and treatment. Despite our lack of clear knowledge in the mechanisms, both methods improved UCVA after the treatments. The improvement in UCVA was not correlated to measured refraction values. UCVA after near work can be improved by repeating near and distant accommodation by fogging and 3D image viewing, although at the different degrees. Further investigation on mechanisms of improvements and their clinical significance are warranted.
    The Open Ophthalmology Journal 10/2013; 7:69-48. DOI:10.2174/1874364101307010069
Show more