1040-5488/14/9106-e156/0 VOL. 91, NO. 6, PP. e156Ye158 OPTOMETRY AND VISION SCIENCE Copyright * 2014 American Academy of Optometry

CORRESPONDENCE

Letter to the Editor: Stereoacuity of Preschool Children with and without Vision Disorders I want to congratulate the Vision in Preschoolers Study Group in its endeavor to measure stereopsis and relate it to the detection of various binocular anomalies.1 We know all the work that goes into the completion of multicenter clinical trials. However, we were very surprised that our earlier work2Y5 and those of others6Y10 were not cited. Before our work, most clinicians used line stereograms such as the Titmus stereo test. 11,12 Simons and Reinecke7 postulated that random dot stereograms (RDSs) could be used to detect amblyopia. We demonstrated that perception of RDSs required both bifoveal fixation and fusion, and thus such a perception could not be made by anyone demonstrating a constant strabismus including microtropia (eccentric fixation angle = objective angle of strabismus).2 Thus, without knowing the fixation pattern, it is difficult to evaluate the ability of an RDS to screen for amblyopia. We determined that an RDS, no matter what the disparity, is a perfect screener for constant strabismus.2 Utilization of a large- or small-disparity RDS seems inappropriate for vision screening, because it will increase either false positive or negative errors. Thus, we used medium-disparity stereograms in our studies in an attempt to enhance responding. Line stereograms, on the other hand, can and should be perceived by small-angle strabismics because line stereopsis does not require fusion for the perception of stereopsis.11,12 Our work determined that when testing with RDS, nonstrabismic amblyopic patients with central fixation often pass an RDS no matter what the disparity is, unless the dot matrix is made small enough to interfere with the global process.2 This is not surprising since Julesz experimentally demonstrated that one could totally blur or magnify either the right or the left eye view by 30%. We are also surprised at the cutoff for amblyopia screening, that is, 20/40. Amblyopia as you know causes more

visual loss in the age group younger than 40 years, thus missing and not treating those with visual acuities from 20/20 to 20/40, which, in our opinion, is a public health problem. Measurement of improvement, in stereoacuity per age group, is not new.4,8,10,13 We are happy to see that your findings replicate our earlier findings. From your article, one might conclude that your methodology was new and unique. In 1979, we compared Titmus, TNO, and Randot and achieved similar findings as yoursVthat test performance improves with age.4 Unlike your assumption, that this might be due to the development of stereopsis, we believed that this was a result of testing. On that basis, we began testing stereopsis using forced-choice paradigm using paired RDS, one with stereopsis versus a second one without.3,5 To enhance responding, we faded out the RDS, which lacked stereopsis and faded out the monocular cue. Upon appropriate responding by pointing and breaking a beam, appropriate reinforcement was administered. We were easily able to demonstrate appropriate stereo responding to an RDS in 2-year-olds using this technique. We were also bothered by two other design problems in your study. First, there are no data on the type of anomaly, for example, constant esotropia, intermittent esotropia, convergence insufficiency,14 divergence excess,15 anisometropic amblyopia, strabismic amblyopia, and microtropia. Each of these binocular anomalies presents different sensorimotor characteristics such that stereoacuity varies tremendously in these subsets from normal to none. Second, the presumption that you are measuring stereoacuity is inaccurate at best. Normal threshold stereoacuity is approximately 20 arcsec and 2 SDs are 40 arcsec.12 Stated another way, your threshold is more than 4 SDs away from the normal stereoacuity. It is like taking visual acuity with the smallest threshold being 20/60. The beauty of using a large-disparity RDS in screening is that almost anyone failing it will have abnormal stereopsis.

The ability of an RDS to properly detect amblyopia without an associated strabismus including microtropia is poor as confirmed by your findings. This clinical dictum that we advocated back in 1978 is still true today.2 Lastly, use of such a large visual acuity level, 20/40, does a disservice to all the amblyopes who have better visual acuity (our definition of amblyopia is a reduction in visual acuity due to visual deprivation [monocular or binocular] that occurs during the critical period). In other words, a patient with OD plano 20/15 OS + 1.50 sph 20/20 would be amblyopic and would require detection and treatment. Detection of intermittent deviations such as divergence excess type or convergence insufficiency just isn’t going to happen using RDS by itself. Unfortunately, preschool screening is not performed adequately. All one needs to pick up the time-sensitive visual anomalies is cycloplegic automated refraction and a large-disparity RDS. Fast, inexpensive, and sensitive. Jeffrey Cooper, MS, OD, FAAO Jerome Feldman, PhD New York, NY

REFERENCES 1. Ciner EB, Ying GS, Kulp MT, Maguire MG, Quinn GE, Orel-Bixler D, Cyert LA, Moore B, Huang J. Stereoacuity of preschool children with and without vision disorders. Vision in Preschoolers Study Group. Optom Vis Sci 2014;91:351Y8. 2. Cooper J, Feldman J. Random-dotstereogram performance by strabismic, amblyopic, and ocular-pathology patients in an operant-discrimination task. Am J Optom Physiol Opt 1978;55:599Y609. 3. Cooper J, Feldman J. Operant conditioning and assessment of stereopsis in young children. Am J Optom Physiol Opt 1978;55:532Y42. 4. Cooper J, Feldman J, Medlin D. Comparing stereoscopic performance of children using the Titmus, TNO, and Randot stereo tests. J Am Optom Assoc 1979;50:821Y5. 5. Feldman J, Cooper J. Rapid assessment of stereopsis in pre-verbal children using

Optometry and Vision Science, Vol. 91, No. 6, June 2014

Copyright © American Academy of Optometry. Unauthorized reproduction of this article is prohibited.

CORRESPONDENCE

6.

7.

8. 9.

10.

11.

12.

13.

14.

15.

operant techniques: a preliminary study. J Am Optom Assoc 1980;51:767Y71. Romano PE, Romano JA, Puklin JE. Stereoacuity development in children with normal binocular single vision. Am J Ophthalmol 1975;79:966Y71. Simons K, Reinecke RD. A reconsideration of amblyopia screening and stereopsis. Am J Ophthalmol 1974;78:707Y13. Simons K. Stereoacuity norms in young children. Arch Ophthalmol 1981;99:439Y45. Frisby JP. Random-dot stereograms for clinical assessment of stereopsis in Bchildren. Dev Med Child Neurol 1975; 17:802Y6. Heron G, Dholakia S, Collins DE, McLaughlan H. Stereoscopic threshold in children and adults. Am J Optom Physiol Opt 1985;62:505Y15. Cooper J. Clinical stereopsis testing: contour and random dot stereograms. J Am Optom Assoc 1979;50:41Y6. Cooper J. Stereopsis. In: Eskridge JB, Amos JF, Bartlett JD, eds. Clinical Procedures in Optometry. Philadelphia, PA: Lippincott; 1991:121Y35. Brown SM, Archer S, Del Monte MA. Stereopsis and binocular vision after surgery for unilateral infantile cataract. J AAPOS 1999;3:109Y13. Cooper J, Jamal N. Convergence insufficiencyVa major review. Optometry 2012;83:137Y58. Cooper J, Medow N. Intermittent exotropia of the divergence excess type: basic and divergence excess type (major review). Bin Vis Eye Mus Surg Q 1993;8: 187Y222.

Authors’ Response We thank Dr. Cooper for taking the time to write a thoughtful Letter to the Editor on our article ‘‘Stereoacuity of Preschool Children with and without Vision Disorders.’’1 We also appreciate his work as a pioneer in the area of stereopsis testing that helped lay the foundation for random dot stereo testing of children. We did in fact acknowledge and cite his related work with preschool children in the introduction of our article.2 The purposes of our article were to evaluate the association between stereoacuity as measured with the Stereo Smile II and the presence, type, and severity of vision disorders in preschool Head Start children and to determine testability and expected levels of stereoacuity in an examination setting for this test. Dr. Cooper questioned our choice of 20/40 as within the range of normal vision

for preschool children. Our choice is well supported by the work of the Vision in Preschoolers (VIP) Study as well as the Multi-Ethnic Pediatric Eye Disease Study and others.3Y6 Our article looked at stereoacuity with regard to four major categories of vision disorders: amblyopia, strabismus, significant refractive error, and reduced visual acuity. Dr. Cooper raises questions with regard to the specific type of strabismus or amblyopia present. Our results showed that, overall, children classified with strabismus or amblyopia did in fact perform more poorly on stereoacuity testing than children without vision disorders.1,7 However, a small subset of children (È9%) with these disorders was able to achieve the best stereoacuity level of 60 arcsec.1 It is possible that one or more of these children may have had intermittent deviations or other anomalies sometimes associated with better levels of stereoacuity. Furthermore, the findings presented in our article showed that most children without vision disorders were more likely to have one of the two best levels of stereopsis on the Stereo Smile II test. In contrast, children with one or more vision disorders detected during a comprehensive vision examination had significantly worse stereoacuity and children with the most severe vision disorders had worse stereoacuity than children with milder disorders. Children who could only complete the demonstration card were 16 times more likely to have a vision disorder. Overall testability for all children was greater than 99%.1 We agree that improvement of stereopsis with age is not new and indeed stated this in our article. We reported the results of stereoacuity testing using the Stereo Smile II from a large sample of 3- to 5-year-old children without vision disorders to establish normative data for each age group using this particular test. Our data showed improvement in stereopsis with age; whether this is due to continued development or other factors related to use of this test is not known. Dr. Cooper also questioned our choice of stereoacuity levels for testing, as the VIP Study did not include finer degrees of disparity, specifically 20 arcsec. Although stereo thresholds of 20 arcsec may have been established for adult populations using the Randot and other tests, this is not the case for stereo thresholds in the

e157

preschool population. Our choice was reasonable based on results from earlier studies using the Stereo Smile and other tests supporting a 60-arcsec threshold.2,8Y15 Dr. Cooper concluded his Letter to the Editor by stating that ‘‘all one needs to pick up the time-sensitive visual anomalies is cycloplegic automated refraction and a large-disparity RDS. Fast, inexpensive, and sensitive.’’ The VIP Study evaluated tests of visual acuity, stereopsis, and refraction in a large-scale study of more than 4000 preschool children with and without vision disorders at five clinical centers throughout the country. All children underwent a comprehensive cycloplegic vision examination by study-trained and certified pediatric optometrists and pediatric ophthalmologists to ascertain the sensitivity and specificity of each screening test as well as combination of tests.7,16,17 Noncycloplegic autorefraction (using the Retinomax or SureSight Vision Screener) or a 5-foot LEA crowded symbol test was among the best tests with sensitivity for strabismus increased by adding the Stereo Smile. These and other findings from the VIP Study are reported in a number of articles.1,3,4,7,16Y18 Elise B. Ciner, OD, FAAO Gui-Shuang Ying, PhD Philadelphia, PA Marjean Taylor Kulp, OD, MS, FAAO Columbus, OH Maureen G. Maguire, PhD Graham E. Quinn, MD, MSCE Philadelphia, PA Deborah Orel-Bixler, OD, PhD, FAAO Berkeley, CA Lynn A. Cyert, PhD, OD, FAAO Tahlequah, OK Bruce Moore, OD, FAAO Boston, MA Jiayan Huang, MS Philadelphia, PA Vision in Preschoolers (VIP) Study Group

REFERENCES 1. Ciner EB, Ying GS, Kulp MT, Maguire MG, Quinn GE, Orel-Bixler D, Cyert LA, Moore B, Huang J, Vision in Preschoolers Study Group. Stereoacuity of preschool children with and without vision disorders. Optom Vis Sci 2014;91:351Y8.

Optometry and Vision Science, Vol. 91, No. 6, June 2014

Copyright © American Academy of Optometry. Unauthorized reproduction of this article is prohibited.

e158 CORRESPONDENCE 2. Cooper J, Feldman J. Operant conditioning and assessment of stereopsis in young children. Am J Optom Physiol Opt 1978; 55:532Y42. 3. Vision in Preschoolers Study Group. Effect of age using Lea Symbols or HOTV for preschool vision screening. Optom Vis Sci 2010;87:87Y95. 4. Cyert L, Schmidt P, Maguire M, Moore B, Dobson V, Quinn G. Threshold visual acuity testing of preschool children using the crowded HOTV and Lea Symbols acuity tests. Vision in Preschoolers Study Group. J AAPOS 2003;7:396Y9. 5. Pan Y, Tarczy-Hornoch K, Cotter SA, Wen G, Borchert MS, Azen SP, Varma R. Visual acuity norms in pre-school children: the Multi-Ethnic Pediatric Eye Disease Study. Optom Vis Sci 2009;86:607Y12. 6. Committee on Practice and Ambulatory Medicine, Section on Ophthalmology, American Association of Certified Orthoptists, American Association for Pediatric Ophthalmology and Strabismus, American Academy of Ophthalmology. Eye examination in infants, children, and young adults by pediatricians. Pediatrics 2003;111:902Y7. 7. Schmidt P, Maguire M, Dobson V, Quinn G, Ciner E, Cyert L, Kulp MT,

8.

9.

10.

11.

12.

Moore B, Orel-Bixler D, Redford M, Ying GS. Comparison of preschool vision screening tests as administered by licensed eye care professionals in the Vision in Preschoolers Study. Vision in Preschoolers (VIP) Study Group. Ophthalmology 2004;111:637Y50. Leat SJ, Pierre JS, Hassan-Abadi S, Faubert J. The moving Dynamic Random Dot Stereosize test: development, age norms, and comparison with the Frisby, Randot, and Stereo Smile tests. J Pediatr Ophthalmol Strabismus 2001;38:284Y94. Ciner EB, Schanel-Klitsch E, Scheiman M. Stereoacuity development in young children. Optom Vis Sci 1991;68:533Y6. Afsari S, Rose KA, Pai AS, Gole GA, Leone JF, Burlutsky G, Mitchell P. Diagnostic reliability and normative values of stereoacuity tests in preschool-aged children. Br J Ophthalmol 2013;97:308Y13. Birch E, Williams C, Drover J, Fu V, Cheng C, Northstone K, Courage M, Adams R. Randot Preschool Stereoacuity Test: normative data and validity. J AAPOS 2008;12:23Y6. Tomac S, Altay Y. Near stereoacuity: development in preschool children; normative values and screening for binocular vision abnormalities; a study of 115

13.

14.

15.

16.

17.

18.

children. Binocul Vis Strabismus Q 2000; 15:221Y8. Cooper J, Feldman J, Medlin D. Comparing stereoscopic performance of children using the Titmus, TNO, and Randot stereo tests. J Am Optom Assoc 1979;50:821Y5. Romano PE, Romano JA, Puklin JE. Stereoacuity development in children with normal binocular single vision. Am J Ophthalmol 1975;79:966Y71. Simons K. Stereoacuity norms in young children. Arch Ophthalmol 1981;99: 439Y45. Vision in Preschoolers (VIP) Study Group. Preschool vision screening tests administered by nurse screeners compared with lay screeners in the vision in preschoolers study. Invest Ophthalmol Vis Sci 2005;46:2639Y48. Kulp MT, Vision in Preschoolers Study G. Findings from the Vision in Preschoolers (VIP) Study. Optom Vis Sci 2009;86:619Y23. Erratum in: Optom Vis Sci. 2009;86:1026. Center for Preventative Ophthalmology and Biostatistics (CPOB). CPOB Publications: Vision in Preschoolers (VIP) Study Publications. Available at http://www.med.upenn. edu/cpob/publications_main.shtml#D1.

Optometry and Vision Science, Vol. 91, No. 6, June 2014

Copyright © American Academy of Optometry. Unauthorized reproduction of this article is prohibited.

Letter to the editor: stereoacuity of preschool children with and without vision disorders.

Letter to the editor: stereoacuity of preschool children with and without vision disorders. - PDF Download Free
100KB Sizes 0 Downloads 3 Views