Enhancement of Emmetropization in Hyperopic Infants

To determine if wearing a moderate spectacle under-correction (3.00D) and performing activities designed to stimulate accurate accommodation during a 15-month period will enhance emmetropization in highly hyperopic (between +5.00D and +7.00D) 3-month old infants.

The purpose of the project is to determine if emmetropization can be enhanced in very farsighted babies. We will give them glasses with a partial correction, an amount that is less than their full degree of farsightedness but enough to put them in the zone of effective emmetropization. This 'boost' is meant to enable very farsighted babies to use their eyes in a normal way and emmetropize as normal infants. This partial correction would be given at 3 months of age for a period of up to 15 months. A program of visual engagement is also provided in order to encourage the normal development and use of accommodation. As changes in farsightedness occur, the power of the glasses will be reduced at follow up appointments to keep the farsightedness within the zone of effective emmetropization. Once an infant reaches a normal amount of farsightedness, the glasses would be discontinued.

Infants will receive spectacles with 3.00D of under-correction relative to the spherical equivalent in each eye as measured by the cycloplegic retinoscopy performed at baseline. They will also receive the full amount of measured astigmatism in their glasses. Changes in spectacle lens power will be made as needed at follow-up visits to keep the level of under-correction within 0.50D of the target 3.00D. A program of visual engagement is also provided to encourage the normal development and use of accommodation. Treatment will continue for 15 months (until 18 months of age) or until the infant reaches a spherical equivalent refractive error of +3.00D or less hyperopia.

The primary outcome will be to determine if the criterion level for emmetropization (≤+3.00D by 18 months of age) is met and maintained by at least 70% of treated infants.

Inclusion Criteria: 3 months of age (between 8 weeks and 20 weeks)at the baseline examination Either gender, any ethnicity Birthweight greater than 2500g Normal pregnancy and delivery (including Cesarean section delivery but excluding serious complications or conditions such as eclampsia or rubella) Hyperopia of +5.00D or more but less than +7.00D spherical equivalent refractive error in each eye by cycloplegic retinoscopy using cyclopentolate 1% Currently under the care of a pediatrician Exclusion Criteria: Anisometropia greater than 1.00D (difference in spherical equivalent) Strabismus Previous history of difficulty with pupillary dilation History of cardiac, liver, asthma, or other respiratory disease History of ocular disease or active ocular inflammation

Atkinson J, Anker S, Bobier W, Braddick O, Durden K, Nardini M, Watson P. Normal emmetropization in infants with spectacle correction for hyperopia. Invest Ophthalmol Vis Sci. 2000 Nov;41(12):3726-31.

Ingram RM, Gill LE, Lambert TW. Effect of spectacles on changes of spherical hypermetropia in infants who did, and did not, have strabismus. Br J Ophthalmol. 2000 Mar;84(3):324-6. doi: 10.1136/bjo.84.3.324.

Mutti DO, Mitchell GL, Jones LA, Friedman NE, Frane SL, Lin WK, Moeschberger ML, Zadnik K. Axial growth and changes in lenticular and corneal power during emmetropization in infants. Invest Ophthalmol Vis Sci. 2005 Sep;46(9):3074-80. doi: 10.1167/iovs.04-1040.

Mutti DO, Mitchell GL, Jones LA, Friedman NE, Frane SL, Lin WK, Moeschberger ML, Zadnik K. Refractive astigmatism and the toricity of ocular components in human infants. Optom Vis Sci. 2004 Oct;81(10):753-61. doi: 10.1097/00006324-200410000-00007.

Anker S, Atkinson J, Braddick O, Nardini M, Ehrlich D. Non-cycloplegic refractive screening can identify infants whose visual outcome at 4 years is improved by spectacle correction. Strabismus. 2004 Dec;12(4):227-45. doi: 10.1080/09273970490517935.

Hung LF, Crawford ML, Smith EL. Spectacle lenses alter eye growth and the refractive status of young monkeys. Nat Med. 1995 Aug;1(8):761-5. doi: 10.1038/nm0895-761.

Schaeffel F, Glasser A, Howland HC. Accommodation, refractive error and eye growth in chickens. Vision Res. 1988;28(5):639-57. doi: 10.1016/0042-6989(88)90113-7.

Smith EL 3rd, Hung LF. The role of optical defocus in regulating refractive development in infant monkeys. Vision Res. 1999 Apr;39(8):1415-35. doi: 10.1016/s0042-6989(98)00229-6.