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Charlotte Lozier Institute

Phone: 202-223-8073
Fax: 571-312-0544

2776 S. Arlington Mill Dr.
#803
Arlington, VA 22206

The
Voyage of Life

Eye Formation

Dive Deeper
Baby's eyes form from the interaction of nervous tissue, outer tissue called ectoderm starting in the sixth week. At birth, the newborn is born able to see, but with such low visual acuity that she is legally blind. Visual experience outside the womb helps the visual system finish developing. (Image Credit: Science Source)

The eyes begin forming 22 days after conception, also known as 5 weeks and 1 day gestation.1 Tissue from the developing brain pushes forward towards the face to form an optic cup and the beginnings of the optic nerve, which will connect the eye to the brain. The optic cup becomes the back of the eye, called the retina, which turns light energy into neural signals. The front of the eye, including the cornea and the lens, both form from the surface tissue. Instead of becoming skin, chemical messages from the optic cup turn these structures into transparent tissue. In week eight, more surface tissue interacts with the cornea and lens to form the embryo’s eyelids.2 Interestingly, the embryo’s eyelids actually fuse together around 10 weeks, and only reopen around 26 weeks.3

The optic cup is shaped like a catcher’s mitt and forms the back of the eye. The front layer of the optic cup will become the colorful iris and the muscles that change the size of the pupil. The back layer of the optic cup will become the light-sensitive receptors in the retina and the neurons that connect the retina to the brain. In week 9 the pigments in the retina are visible. Also, the critical neural connection between the back of the eye and the brain, called the optic nerve, has formed.4

The front and back of the eyeball fuse together by week 10, and muscles start moving the eyes by week 12.5 Eye movements can be detected by ultrasound starting in week 14,6 and can reveal whether a baby is awake, asleep, or dreaming starting in week 23.7

The light-sensitive receptors in the retina are called rods and cones. Interestingly, just as neurons stop forming late in pregnancy, new rods and cones stop forming too. Cells stop dividing in the center of the retina, called the fovea, around 16 weeks gestation, and cells stop dividing in the outer ring of the retina around 31 weeks.8 Rods let the eyes detect very small amounts of light, and they detect light at the edges of a person’s vision. By contrast, cones mostly detect light in the center of a person’s vision and produce sharp, colorful images. Adults have 100 million rods and 7 million cones in each eye.9 Rods and cones are formed all over the retina, but in adults, rods are mostly found in the periphery and cones are found in the fovea. Cones move towards the center of the retina, called the fovea, and rods move out of the fovea throughout pregnancy and for many months after birth.10 In fact, the fine maturity of cones is not complete until at least 4 years old.11

Premature infants can look at objects or lights starting between 30 and 32 weeks. These infants start moving their eyes to track moving objects at 34 weeks.12 Interestingly, they look preferentially at a pattern over a gray circle starting at 34 weeks. This is especially impressive because their visual acuity is around 20/2000.13 Simply put, that means that an object that an average adult could see 2000 feet away would need to be just 20 feet away for the baby to be able to see it. For perspective, a person is legally blind if their visual acuity is 20/200 or worse. Babies have adult levels of visual acuity around 3 or 4 years old.14

Most infants are born with light blue or gray eyes. A baby’s eye color finalizes between 6 and 12 months old. The color is determined by the distribution of melanin in the iris. Melanin is the same pigment that gives skin its color. If the melanin stays at the back of the iris, then the eye will be blue. If the melanin is found all over the supporting tissue in the iris, then the eye will be brown.15

Major milestones in eye development:

Gestational Age Milestone
Week 6 Lens placode and optic vesicles form.16
Week 8 Pigments developing in retina.17 Eyelids form.18
Week 10 The eyeballs finish forming.19 Eyelids fuse together.20
Week 11 Rods and cones start forming.21
Week 12 First eye movements detected.22
Week 14 Several eyelashes have formed.23 Spontaneous eye movements begin.24
Week 23 Rapid eye movements begin. 25
Week 26 Eyelids reopen.26
Week 28 First fetal responses to light.27
Week 31 Fetal pupils constrict and dilate in response to light.28
Week 32 Premature infants can fixate on lights.29
Week 33 Consistent blinking begins.30
Week 34 Premature infants can visually track a moving object.31
Back to The Voyage of Life
Sources
  1. Moore, Keith L, TVN Persaud, and Mark G. Torchia. The Developing Human, Clinically Oriented Embryology. 10th ed. Philadelphia: Elsevier, 2016.
  2. Moore, Keith L, TVN Persaud, and Mark G. Torchia. The Developing Human, Clinically Oriented Embryology. 10th ed. Philadelphia: Elsevier, 2016.
  3. Hatem A. Tawfik et al., “Embryologic and Fetal Development of the Human Eyelid,” Ophthalmic Plastic and Reconstructive Surgery 32, no. 6 (November 2016): 407–14, https://doi.org/10.1097/IOP.0000000000000702.
  4. Moore, Keith L, TVN Persaud, and Mark G. Torchia. The Developing Human, Clinically Oriented Embryology. 10th ed. Philadelphia: Elsevier, 2016.
  5. Humphrey, Tryphena. “Some Correlations between the Appearance of Human Fetal Reflexes and the Development of the Nervous System.” In Progress in Brain Research, edited by Dominick P. Purpura and J. P. Schadé, 4:93–135. Growth and Maturation of the Brain. Elsevier, 1964. https://doi.org/10.1016/S0079-6123(08)61273-X; Moore, Keith L, TVN Persaud, and Mark G. Torchia. The Developing Human, Clinically Oriented Embryology. 10th ed. Philadelphia: Elsevier, 2016.
  6. Horimoto et al., “Fetal Eye Movements,” Ultrasound in Obstetrics & Gynecology 3, no. 5 (1993): 362–69, https://doi.org/10.1046/j.1469-0705.1993.03050362.x.
  7. Birnholz, J. C. (1981). The development of human fetal eye movement patterns. Science, 213(4508), 679-681. DOI:10.1126/science.7256272.
  8. Provis, J. M., Van Driel, D., Billson, F. A., & Russell, P. (1985). Development of the human retina: patterns of cell distribution and redistribution in the ganglion cell layer. Journal of comparative neurology, 233(4), 429-451. https://doi.org/10.1002/cne.902330403.
  9. Guyton, AC, and JE Hall. Textbook of Medical Physiology. 10th ed. Philadelphia: W.B. Saunders, 2000.
  10. Birch, Eileen E., and Anna R. O'Connor. 'Preterm birth and visual development.' In Seminars in Neonatology, vol. 6, no. 6, pp. 487-497. WB Saunders, 2001. https://doi.org/10.1053/siny.2001.0077.
  11. Yuodelis, C., & Hendrickson, A. (1986). A qualitative and quantitative analysis of the human fovea during development. Vision research, 26(6), 847-855. https://doi.org/10.1016/0042-6989(86)90143-4.
  12. Ricci, D., Romeo, D. M., Serrao, F., Gallini, F., Leone, D., Longo, M., … Mercuri, E. (2010). Early assessment of visual function in preterm infants: How early is early? Early Human Development, 86(1), 29–33. https://doi.org/10.1016/j.earlhumdev.2009.11.0.
  13. Brown, A. M., & Yamamoto, M. (1986). Visual acuity in newborn and preterm infants measured with grating acuity cards. American journal of ophthalmology, 102(2), 245-253. https://doi.org/10.1016/0002-9394(86)90153-4.
  14. Birch, Eileen E., and Anna R. O'Connor. 'Preterm birth and visual development.' In Seminars in Neonatology, vol. 6, no. 6, pp. 487-497. WB Saunders, 2001. https://doi.org/10.1053/siny.2001.0077.
  15. Moore, Keith L, TVN Persaud, and Mark G. Torchia. The Developing Human, Clinically Oriented Embryology. 10th ed. Philadelphia: Elsevier, 2016.
  16. Sadler, Thomas W. Medical Embyrology. 14th ed., 2019.
  17. Yang S, Zhou J, Li D. Functions and Diseases of the Retinal Pigment Epithelium. Front Pharmacol. 2021 Jul 28;12:727870. doi: 10.3389/fphar.2021.727870
  18. Moore, Keith L, TVN Persaud, and Mark G. Torchia. The Developing Human, Clinically Oriented Embryology. 10th ed. Philadelphia: Elsevier, 2016.
  19. Kwan, Kristen M., Hideo Otsuna, Hinako Kidokoro, Keith R. Carney, Yukio Saijoh, and Chi-Bin Chien. “A Complex Choreography of Cell Movements Shapes the Vertebrate Eye.” Development (Cambridge, England) 139, no. 2 (January 2012): 359–72. https://doi.org/10.1242/dev.071407.
  20. Tawfik, Hatem A., Mohamed H. Abdulhafez, Yousef A. Fouad, and Jonathan J. Dutton. “Embryologic and Fetal Development of the Human Eyelid.” Ophthalmic Plastic and Reconstructive Surgery 32, no. 6 (November 2016): 407–14. https://doi.org/10.1097/IOP.0000000000000702.
  21. Hendrickson, Anita, Keely Bumsted-O’Brien, Riccardo Natoli, Visvanathan Ramamurthy, Daniel Possin, and Jan Provis. “Rod Photoreceptor Differentiation in Fetal and Infant Human Retina.” Experimental Eye Research 87, no. 5 (November 2008): 415–26. https://doi.org/10.1016/j.exer.2008.07.016.
  22. Humphrey, Tryphena. “Some Correlations between the Appearance of Human Fetal Reflexes and the Development of the Nervous System.” In Progress in Brain Research, edited by Dominick P. Purpura and J. P. Schadé, 4:93–135. Growth and Maturation of the Brain. Elsevier, 1964. https://doi.org/10.1016/S0079-6123(08)61273-X.
  23. Tawfik, Hatem A., Mohamed H. Abdulhafez, Yousef A. Fouad, and Jonathan J. Dutton. “Embryologic and Fetal Development of the Human Eyelid.” Ophthalmic Plastic and Reconstructive Surgery 32, no. 6 (November 2016): 407–14. https://doi.org/10.1097/IOP.0000000000000702.
  24. Horimoto et al., “Fetal Eye Movements,” Ultrasound in Obstetrics & Gynecology 3, no. 5 (1993): 362–69, https://doi.org/10.1046/j.1469-0705.1993.03050362.x.
  25. Birnholz, J. C. (1981). The development of human fetal eye movement patterns. Science, 213(4508), 679-681. DOI:10.1126/science.7256272.
  26. Tawfik, Hatem A., Mohamed H. Abdulhafez, Yousef A. Fouad, and Jonathan J. Dutton. “Embryologic and Fetal Development of the Human Eyelid.” Ophthalmic Plastic and Reconstructive Surgery 32, no. 6 (November 2016): 407–14. https://doi.org/10.1097/IOP.0000000000000702.
  27. Hari Eswaran et al., “Functional Development of the Visual System in Human Fetus Using Magnetoencephalography,” Neuroimaging of Functional Development in Fetuses and Newborns 190 (November 1, 2004): 52–58, https://doi.org/10.1016/j.expneurol.2004.04.007.
  28. Donovan, T., Dunn, K., Penman, A., Young, R. J., & Reid, V. M. (2020). Fetal eye movements in response to a visual stimulus. Brain and Behavior, 10(8), e01676. https://doi.org/10.1002/brb3.1676; Robinson, R. J., and J. P. Tizard. “The Central Nervous System in the Newborn.” British Medical Bulletin 22, no. 1 (January 1966): 49–55. https://doi.org/10.1093/oxfordjournals.bmb.a070436.
  29. Ricci, D., Romeo, D. M., Serrao, F., Gallini, F., Leone, D., Longo, M., … Mercuri, E. (2010). Early assessment of visual function in preterm infants: How early is early? Early Human Development, 86(1), 29–33. https://doi.org/10.1016/j.earlhumdev.2009.11.0.
  30. Tawfik, Hatem A., Mohamed H. Abdulhafez, Yousef A. Fouad, and Jonathan J. Dutton. “Embryologic and Fetal Development of the Human Eyelid.” Ophthalmic Plastic and Reconstructive Surgery 32, no. 6 (November 2016): 407–14. https://doi.org/10.1097/IOP.0000000000000702.
  31. Ricci, D., Romeo, D. M., Serrao, F., Gallini, F., Leone, D., Longo, M., … Mercuri, E. (2010). Early assessment of visual function in preterm infants: How early is early? Early Human Development, 86(1), 29–33. https://doi.org/10.1016/j.earlhumdev.2009.11.0.
See Full Bibliography

All images and illustrations on The Voyage of Life were reviewed by credentialed scientists for accuracy.

Medical art animation was used to provide a schematic representation of fetal development, with some features, including timing, not to scale. The animation was chosen as an ethically uncompromised guide to fetal development. There are many real human images at each developmental age showing the most accurate fetal forms throughout development. A concerted effort was made to use images and material in which the human embryo or fetus did not undergo any known harm.

Page last updated on November 25, 2023
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