The human eye undergoes dramatic anatomical and physiologic development throughout infancy and early childhood (Table 15-1). Ophthalmologists caring for pediatric patients should be familiar with the normal growth and development of the child’s eye because departures from the norm may indicate pathology. See also BCSC Section 2, Fundamentals and Principles of Ophthalmology.
Dimensions of the Eye
Most of the growth of the eye takes place in the first year of life. Change in the eye’s axial length occurs in 3 phases. The first phase (birth to age 2 years) is a period of rapid growth: the axial length increases by approximately 4 mm in the first 6 months of life and by an additional 2 mm during the next 6 months. During the second (age 2 to 5 years) and third (age 5 to 13 years) phases, growth slows, with axial length increasing by about 1 mm per phase.
Similarly, with growth of the globe, the corneal diameter increases rapidly during the first year of life. The average horizontal diameter of the cornea is 9.5–10.5 mm in newborns and increases to 12.0 mm in adults. The cornea also flattens in the first year such that keratometry values change markedly, from approximately 52.00 diopters (D) at birth, to 46.00 D by age 6 months, to adult measurements of 42.00–44.00 D by age 12 months. Mild corneal clouding may be seen in healthy newborns and is common in premature infants. It resolves as the cornea gradually becomes thinner, decreasing from an average central thickness of 691 μm at 30–32 weeks’ gestation to 564 μm at birth.
The power of the pediatric lens decreases dramatically over the first several years of life—an important consideration when intraocular lens implantation is planned for infants and young children after cataract extraction. Lens power decreases from approximately 35.00 D at birth to about 23.00 D at age 2 years. Subsequently, the change is more gradual: lens power decreases to approximately 19.00 D by age 11 years, with little or no change thereafter.
Table 15-1 Dimensions of Newborn and Adult Eyes
Gordon RA, Donzis PB. Refractive development of the human eye. Arch Ophthalmol. 1985; 103(6):785–789.
Kirwan C, O’Keefe M, Fitzsimon S. Central corneal thickness and corneal diameter in premature infants. Acta Ophthalmol Scand. 2005;83(6):751–753.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.