Accommodation

David A. Berntsen, Loraine T. Sinnott, Donald O. Mutti, Karla Zadnik, and The CLEERE Study Group.(2011) Accommodative lag and juvenile-onset myopia progression in children wearing refractive correction . (ABSTRACT) Vision Research Volume 51, Issue 9, 11 May 2011, Pages 1039-1046 doi:10.1016/j.visres.2011.02.016

MyopiaPrevention.org comment: 592 myopia children wearing full refractive correction were tested for the amount of accomdative lag at the beginning and end of one year. No correlation could be found between the amount of lag and the amount of progression. The results would suggest that accommodative lag does not drive myopic progression and thus treatment of accommodative lag may not have much effect on slowing progresssion.

Tarczy-Hornoch, Kristina.(2009) Modified Bell Retinoscopy: Measuring Accommodative Lag in Children. (ABSTRACT) Optometry and Vision Science December 2009, Volume 86, Issue 12: pp 1337-1345

MyopiaPrevention.org comment: "modified bell retinoscopy" whereby "the target is advanced toward the patient until the retinoscopic reflex is neutralized" was compared with "Nott retinoscopy (NR) and the monocular estimate method (MEM)". The authors conclude: "MBR may be a useful addition to the repertoire of clinical tools available for assessing accommodation in young children." For clinicians, the method may simplify the testing of lag.

Allen PM, Radhakrishnan H, Rae S, Calver RI, Theagarayan BP, Nelson P, Osuobeni E, Sailoganathan A, Price H, O'Leary DJ.(2009) Aberration control and vision training as an effective means of improving accommodation in individuals with myopia. (ABSTRACT) Investigative Ophthalmology and Visual Science. 2009 Nov;50(11):5120-9. Epub 2009 Jul 30.

MyopiaPrevention.org comment: A study of custom designed soft contact lenses that reduced lag of accommodation.

Troilo, David; Totonelly, Kristen; Harb, Elise.(2009) Imposed Anisometropia, Accommodation, and Regulation of Refractive State. (FULL TEXT) Optom Vis Sci. 2009 January; 86(1): E31–E39.

MyopiaPrevention.org comment: (Marmosets in this study are small primates, not the large squirrels called marmots.) The maturing animals responded as expected to plus and minus contact lenses (minus lens eyes grew myopic and plus lens eyes grew more hyperopic; plus lens eyes did not grow smaller). In the animals with one plus lens, the non-treated control eye grew somewhat longer than the control eyes from minus lens animals, opposite to the effect of the treated eye. The results are discussed in relation to accommodation and the possible role that the temporal (time of day) pattern of accommodation plays in emetropization.

Lundstrom, L., Mira-Agudelo, A., & Artal, P. (2009). Peripheral optical errors and their change with accommodation differ between emmetropic and myopic eyes. (FULL TEXT) Journal of Vision, 9(6):17, 1-11

MyopiaPrevention.org comment: Emmetropes became more myopic peripherally with accommodation than the myopes. A small (10 eyes) study. If peripheral myopia is protective against myopic progression, this accommodative phenomena may further explain emmetropization.

L N Davies, E A H Mallen (2009) Influence of accommodation and refractive status on the peripheral refractive profile. (ABSTRACT) Br J Ophthalmology 2009;93:1186-1190

MyopiaPrevention.org comment: A study of 80 eyes. While emmetropes started with peripheral myopia and myopes started with peripheral hypermetropia, accommodation did not significantly change the peripheral refraction between the two groups. In other words, emmetropes didn't accommodate differently. And myopes can't get rid of their peripheral hyperopia when reading.

Mutti DO, Mitchell GL, Jones LA, Friedman NE, Frane SL, Lin WK, Moeschberger ML, Zadnik K.(2009) Accommodation, acuity, and their relationship to emmetropization in infants. (FULL TEXT) Optometry and Vision Science June 2009 - Volume 86 - Issue 6 - pp 666-676

MyopiaPrevention.org comment: Defocus (lag) was measured at distance and near in infants at 3, 9 and 18 months of age. Results showed that the cycloplegic refraction was the best predictor of emmetropization at 18 months. Hyperopic defocus did not correlate with change in refractive error. However, the defocus or lag was measured centrally, not peripherally. The authors consider accommodative response to be a "plausible visual signal for emmetropization" since infants who accommodated more accurately were able to more accurately modify their refractive error towards emmetropization.

Vasudevan B, Ciuffreda KJ, Ludlam DP. (2009) Accommodative training to reduce nearwork-induced transient myopia. (ABSTRACT) Optom Vis Sci. 2009 Nov;86(11):1287-94.

MyopiaPrevention.org comment: Ten young adult progressing myopes were given specific home eye exercises for increased flexibility of the focusing system over 6 weeks. The result was that the transient myopia produced by near work went away faster. If transient myopia is a risk factor for permanent myopia, specific eye exercises may help prevent progression.

Andrew Whatham, Frederik Zimmermann, Aldo Martinez, Stephanie Delgado, Percy Lazon de la Jara, Padmaja Sankaridurg, Arthur Ho. (2009) Influence of accommodation on off-axis refractive errors in myopic eyes. (FULL TEXT) Journal of Vision March 20, 2009 vol. 9 no. 3 article 14

MyopiaPrevention.org comment: How the refraction varied at different peripheral angles during accommodation was studied, not whether the eye was actually myopic or hyperopic at any one location during a specific level of accommodation. Accommodation caused the near-periphery to shift towards more hyperopia and the far-periphery to shift towards more myopia than the central vision shift in focus.

Lan Weizhong, Yang Zhikuan, Liu Wen, Chen Xiang, Ge Jian.(2008) A longitudinal study on the relationship between myopia development and near accommodation lag in myopic children. (FULL TEXT) Ophthalmic and Physiological Optics Volume 28, Issue 1, pages 57–61, January 2008DOI: 10.1111/j.1475-1313.2007.00536.x

MyopiaPrevention.org comment: It has been proposed that those students with an accommodative lag were more likely to be or become myopic. It has been shown (the COMET trial) that a subset of students - those with a near eso and an accommodative lag - formed a group that was most likely to benefit from a multifocal spectacle correction in slowing myopic progression. This current study could find no relation between those with an accommodative lag and those that progressed in their myopia. Taken together, the two studies may indicate that while accommodative lag helps identify those who are most likely to benefit from multifocal spectacles, the mere presence of a lag is not sufficient to identify those needing treatment. Further studies could help to better define these parameters.

Allen PM, O'Leary DJ (2006). Accommodation functions: co-dependency and relationship to refractive error. (ABSTRACT) Vision Res 46: 491-505

MyopiaPrevention.org comment: "Facility of accommodation and accommodative lag (were) independent predictors of myopia progression." In other words, children who were poor at focusing accurately at close distances were more likely to become myopic.

Donald O. Mutti, G. Lynn Mitchell, John R. Hayes, Lisa A. Jones, Melvin L. Moeschberger, Susan A. Cotter, Robert N. Kleinstein, Ruth E. Manny, J. Daniel Twelker, Karla Zadnik, and the CLEERE Study Group. (2006) Accommodative lag before and after the onset of myopia. (FULL TEXT) Invest Ophthalmol Vis Sci. 47: 837-46.

MyopiaPrevention.org comment: Increased accommodative lag did not appear to be predictive of future myopia but rather a result of myopic development. In other words, treating accommodative lag to prevent myopia probably wouldn't work.

Phillips JR (2005). Monovision slows juvenile myopia progression unilaterally (FULL TEXT) Br J Ophthalmol. 89: 1196-200

MyopiaPrevention.org comment: An interesting study. Eighteen myopic children average age 11.6 were fit with glasses so that the dominant eye was fully corrected for distance and the other eye was left uncorrected or under corrected if needed to keep the difference at or below 2.00 diopters, a technique commonly called monovision. All children used the dominant near eye to read and thus the uncorrected eye was always in myopic defocus, even when reading. Monovision thus does not reduce accommodation in juvenile eyes. But myopic progression in the under corrected eye was .36D/year less than the fully corrected eye, indicating that myopic defocus slowed myopic progression, unrelated to accommodative effort. This myopic defocus (under corrected) eye became only half as myopic as the other eye. This is different than under correcting both eyes where there is myopic defocus at distance but clear or hyperopic focus for near tasks due to accommodation.

J A Guggenheim and C H To.(2005) Monovision slows myopia progression. (FULL TEXT) Br J Ophthalmol. 2005 September; 89(9): 1076–1077.

MyopiaPrevention.org comment: This discusses the article in the same issue: "Monovision slows juvenile myopia progression unilaterally", also covering many aspects of myopia progression and control and holding out better hope for an optical solution.

Abbott ML, Schmid KL, Strang NC. (1998). Differences in the accommodation stimulus response curves of adults myopes and emmetropes. (ABSTRACT) Ophthalmic Physiol Opt. 18: 13-20

MyopiaPrevention.org comment: Progressing myopes showed a greater lag of accommodation than stable myopes.

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