At the turn of the last century William James speculated that the sensory world of an infant would be a “blooming, buzzing confusion.” In fact, relatively little was known about visual development in infants and young children until the 1950s and 1960s, just before Velma embarked on her scientific career. With the advent of new techniques to assess systematically the vision of non-verbal, seemingly uncooperative subjects, a great deal has now been learned about vision in the first months and years after birth.
Although specific information was being gathered from infants and young children, neuroscientists were demonstrating that visual experience could alter the neural circuitry of the developing brain. These insights had implications for the management and treatment of amblyopia. The demonstration of a sensitive period of cortical plasticity was good news in that it held promise for success in the treatment of experience-dependent conditions, but it was also bad news in that it demonstrated that the window of opportunity for aggressive treatment is early in childhood and relatively short.
Velma’s work and career exemplify the integration of two key themes in understanding the development of vision in infants and children. The first has been to ask fundamental questions about the development of visual abilities in infants and how these skills integrate with other aspects of their motor and cognitive development. The second has been to ask how clinicians might be able to detect, diagnose, treat, and potentially prevent permanent visual abnormality during the first postnatal years.
These two approaches were apparent in a major review published in the early 1990s. Chapters written by a group of scientists and clinicians, including Velma, were compiled and edited by Kurt Simons into the highly cited and referenced book, “Early Visual Development, Normal and Abnormal.” This current feature issue of OVS, 16 years on, has provided an excellent opportunity to reflect on these themes in the context of additional knowledge. The contributions to this issue illustrate the number of paths that have been taken in the past two decades.
The development of the optics of the eye has attracted significant attention for three clinically important reasons. First, retinal image quality defines the information being presented to the developing neural visual system and we need to ensure that this information is appropriate for normal development during infancy and early childhood. Thus, we need to understand normal refractive development and the interaction between the developing optical and neural visual systems, in the context of amblyopia in particular.1–5 Second, numerous studies have demonstrated the potential for visual experience to influence the growth of the eye. We need to understand the process of emmetropization, and determine whether it can be encouraged through appropriate refractive correction.6,7 Finally, the realization that the incidence and prevalence of myopia is increasing dramatically around the world has revealed an urgent need for understanding the pathological underpinnings of this condition.8–11 We have been able to make real progress in our understanding of refractive development with the relatively recent development of autorefractors and photorefractors, as well as more robust approaches to quantifying refractive error.12,13 However, significant elements of these core questions still remain.
The clinical assessment of the status of the visual system has also attracted attention, from both vision screening and full examination perspectives. There are still significant challenges in obtaining reliable data from “wriggly” children in a screening setting, and we are still some way from reaching a consensus about how best to provide the pediatric population with vision screenings.14 In addition to the impact of the sensitive period, these assessments also need to occur at a young age before children enter school with its additional visual demands.15–17 The recognition that early treatment is frequently beneficial for the developing visual system still drives us to refine techniques for reliably diagnosing, assessing, and monitoring visual status in the general clinical community.18,19 Still, we have basic work to do to develop a clear understanding of the mechanisms and natural history of a number of important and relatively common clinical conditions.4,20 Large-scale population based studies using efficient techniques are still required to determine the risk factors for these conditions and their natural history.
There have also been a number of interesting demonstrations in the past 20 years that visual experience impacts developing neural circuitry at higher stages of processing, and therefore that tools are required to look at the more perceptual and cognitive aspects of function. In this context, there have been a series of studies looking at typical development of these functions and the impact of lower level immaturities on them,21–30 and also of complex and difficult clinical conditions.31–35
An area in which Velma has shown particular strength is the transfer of new knowledge to clinical care. The most significant contribution has likely been her work in two large clinical trials in retinopathy of prematurity (ROP), the Cryotherapy for ROP Study, and the Early Treatment for ROP Trial. By introducing quantitative assessment of grating visual acuity in infants and young children as a major outcome measure in these two studies, an earlier determination of potential functional benefit could be made rather than waiting until the child was able to provide more “standard” measures of acuity. Such outcome measures allowed intervention to be assessed in terms of functional outcome rather than simply the appearance of the ocular structure. It would not be an understatement to posit that introduction of quantitative functional measures, including those of visual acuity and visual field, revolutionized the design of clinical trials in pediatric ophthalmology and optometry and this work will have lasting benefits for our young patients. This laborious task was undertaken with intelligence, honesty, and rigor by the individual to whom this feature issue is dedicated.
As we honor Velma, our mentor, colleague and friend, we trust that this compilation of research will inspire and challenge scientists to further pursuits. In particular, there is still a real need and obligation to help the families of young patients with as much prognostic information as we can develop and gather. Advancing our understanding of basic aspects of the development of extrastriate cortex, visual perception and cognition is a particularly daunting task, given the need for objective assessments in infants and young children. Hopefully, new technologies including innovative forms of brain imaging (e.g., near infrared spectroscopy, multielectrode electroencephalogram, fMRI), will allow us to develop norms and appropriate assessment tools to evaluate therapies for these complex conditions and others.
T. Rowan Candy
E. Eugenie Hartmann
D. Luisa Mayer
Joseph M. Miller
Graham E. Quinn
1. Anderson HA, Glasser A, Stuebing KK, Manny RE. Minus lens stimulated accommodative lag as a function of age. Optom Vis Sci 2009;86:685–93.
2. Candy TR, Wang J, Ravikumar S. Retinal image quality and postnatal visual experience during infancy. Optom Vis Sci 2009;86:566–71.
3. Moseley MJ, Fielder AR, Stewart CE. The optical treatment of amblyopia. Optom Vis Sci 2009;86:629–33.
4. Harvey EM. Development and treatment of astigmatism-related amblyopia. Optom Vis Sci 2009;86:634–9.
5. Lewis TL, Maurer D. The effects of early pattern deprivation on visual development. Optom Vis Sci 2009;86:640–6.
6. Little JA, Woodhouse M, Saunders KJ. Corneal power and astigmatism in Down Syndrome. Optom Vis Sci 2009;86:748–54.
7. Mutti DO, Mitchell GL, Jones LA, Friedman NE, Frane SL, Lin WK, Moeschberger ML, Zadnik K. Accommodation, acuity, and their relationship to emmetropization in infants. Optom Vis Sci 2009;86:666–76.
8. Gwiazda J. Treatment options for myopia. Optom Vis Sci 2009;86:624–8.
9. Marsh-Tootle WL, Dong LM, Hyman L, Gwiazda J, Weise KK, Dias L, Fern KD; the COMET Group. Myopia progression in children wearing spectacles versus switching to contact lenses. Optom Vis Sci 2009;86:741–7.
10. Schultz KE, Sinnott LT, Mutti DO, Bailey MD. Accommodative fluctuations, lens tension and ciliary body thickness. Optom Vis Sci 2009;86:677–84.
11. Sreenivasan V, Irving EL, Bobier WR. Binocular adaptation to +2 D lenses in myopic and emmetropic children. Optom Vis Sci 2009;86:731–40.
12. Howland HC. Photorefraction of eyes: history and future prospects. Optom Vis Sci 2009;86:603–6.
13. Miller JM. Clinical applications of power vectors. Optom Vis Sci 2009;86:599–602.
14. Vision In Preschoolers (VIP) Study Group. Findings from the Vision in Preschoolers (VIP) Study. Optom Vis Sci 2009;86:619–23.
15. Ayton LN, Abel LA, Fricke TR, McBrien NA. The Developmental Eye Movement Test: what is it really measuring? Optom Vis Sci 2009;86:722–30.
16. Powers MK. Paper tools for assessing visual function. Optom Vis Sci 2009;86:613–8.
17. Webber AL, Wood JM, Gole GA, Brown B. Effect of amblyopia on the developmental eye movement test in children. Optom Vis Sci 2009;86:760–6.
18. Drover JR, Wyatt LM, Stager DR Sr, Birch EE. The Teller acuity cards are effective in detecting amblyopia. Optom Vis Sci 2009;86:755–9.
19. Pan Y, Tarczy-Hornoch K, Cotter SA, Wen G, Borchert MS, Azen SP, Varma R; the Multi-Ethnic Pediatric Eye Disease Study (MEPEDS) Group. Visual acuity norms in preschool children: The Multi-Ethnic Pediatric Eye Disease Study. Optom Vis Sci 2009;86:607–12.
20. Fulton AB, Hansen RM, Anne Moskowitz A. Development of rod function in term born and former preterm subjects. Optom Vis Sci 2009;86:653–8.
21. Aslin RN. How infants view natural scenes gathered from a head-mounted camera. Optom Vis Sci 2009;86:561–5.
22. Bennett DM, Gordon G, Duttons GN. The Useful Field of View Test, normative data in children of school age. Optom Vis Sci 2009;86:717–21.
23. Braddick OJ, Atkinson J. Infants’ sensitivity to motion and temporal change. Optom Vis Sci 2009;86:577–82.
24. Brown AM, Lindsey DT. Contrast insensitivity: the critical immaturity in infant visual performance. Optom Vis Sci 2009;86:572–6.
25. Dain SJ, Ling BY. Cognitive abilities of children on a grey seriation test. Optom Vis Sci 2009;86:700–6.
26. Dobkins KR. Does visual modularity increase over the course of development? Optom Vis Sci 2009;86:583–8.
27. García-Quispe LA, Gordon J, Zemon V. Development of contrast mechanisms in humans: a VEP study. Optom Vis Sci 2009;86:707–16.
28. Held R. Visual-haptic mapping and the origin of crossmodal identity. Optom Vis Sci 2009;86:595–8.
29. Quinn PC, Bhatt RS. Perceptual organization in infancy: bottom-up and top-down influences. Optom Vis Sci 2009;86:589–94.
30. Wang YZ, Morale SE, Cousins R, Birch EE. The course of development of global hyperacuity over lifespan. Optom Vis Sci 2009;86:694–9.
31. Birch EE, Jingyun Wang J. Stereoacuity outcomes following treatment of infantile and accommodative esotropia. Optom Vis Sci 2009;86:647–52.
32. Agrawal S, Mayer DL, Hansen RM, Fulton AB. Visual fields in young children treated with vigabatrin. Optom Vis Sci 2009;86:767–73.
33. Good WV. Cortical visual impairment: new directions. Optom Vis Sci 2009;86:663–5.
34. Summers CG. Albinism: classification, clinical characteristics, and recent findings. Optom Vis Sci 2009;86:659–62.
35. Watson T, Orel-Bixler D, Haegerstrom-Portnoy G. VEP vernier, VEP grating and behavioral grating acuity in patients with cortical visual impairment. Optom Vis Sci 2009;86:774–80.