Screening for visual defects in preschoolchildren

Screening for visual defects in preschoolchildren

215 CURRENTOPHTHALMOLOGY become increasingly obvious that alterations in tear film characteristics affecting the health of the cornea may occur with...

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215

CURRENTOPHTHALMOLOGY

become increasingly obvious that alterations in tear film characteristics affecting the health of the cornea may occur with contact lenses and surgery that alters cornea1 topography, as well as with the more widely known conditions associated with altered tear function. The approach described by Dr. Olsen appears to provide a relatively precise method for measuring the thickness of the oily layer of the tear film. This layer is a critical component of tear film. It is hydrophobic and stabilizes the film. In its absence, this stability is destroyed leading to rapid tear loss from the surface by evaporation. Olsen’s method is based on the measurement of reflectivity from the tear film layer and entails the use of a photometer mounted on a slit-lamp to measure reflectivity- at two different wavelengths. In his measurements of normal subjects, Olsen estimated the thickness of the oily layer to be about 40 nm. It will now be important to determine whether the technique is sufficiently sensitive to detect alterations in thickness of the oily layer when the tear film is altered by disease states or other factors. Deu~s O’D;\\ ~.\SH\‘ll.l.l;. TI
Screening for Visual Defects in Preschoolchildren, by R.M. Ingram, W.14’. Holland, Walker, J.M. Wilson, P.E. Arnold, and S. Dally. Br J Ophthalmol 70: 16-21, 1986

C.

In 1976 the Court Report recommended that children have their vision screened at the age of 3% years. Screening at this age is supported on the grounds that squint and amblyopia would be identified at an age when remedial treatment might be successful. However, although a number of trials of screening children at this age have been conducted over the past 20 years, screening has never been continued long enough for a full evaluation. The two most recent reports on the sub.ject have not provided continuing evidence in favor of vision screening at this age. The investigation reported by these authors conducted in a circumscribed area of Northamptonshire attempts to determine to what extent screening of 3lh year-old-children for visual defects would satisfy the criteria for a successful screening examination. It represents a preliminary report of the findings of six years of screening children at this age, and deals with the methods that are available to do this. the visual defects found, and with the followup and treatment offered upon the detection of possible defect. The children screened were born betweenJanuary 1973 and December 1978. The authors conclude from this study that there is no evidence to support the suggestion that a widespread program ofvisual screening at age 3!/~ should be instituted. They discuss practival problems and defects in such a program. They suggest that issues raisrd are to be resolved by the research identification of preschool children who ha1.e visual problems, and will be facilitated by a screening procedure including refraction and a possible cover test. (r\uthor’s address: I)r. R.M. Ingraham, Kettrrinq and District General Hospital, Rothwcll Road. Krttcrinq Northants NNl68U%)

Comment The conclusion of this paper is noteworthy. “There is no evidence to support the suggestion that a widespread programme(sic) of vision screening at age 3.5 should be instituted.” To place this conclusion in perspective it may be helpful to summarize the authors’ other work and to inspect the data to which they refer in support of this conclusion. As to the first: the primary author (Ingram) has long been fascinated by the use of refraction techniques to screen infants as opposed to the 3.5-year-olds of this study. In fact, of 21 articles found in a Medline data search under the author’s name, 13 of them (62%) are on some facet of refraction screening. An investigator, who has testing biases such as Ingram may have had, may inadvertently introduce errors into their study. For example, in this article the author introduces the refractive screening methodology as a suggested technique in one-year-olds while the article should have been exclusively studying the 3.5 yearold age group. In addition to my concern about possible bias on the part of the investigators, we should also take a careful look at the data. As to the pool of children in the study, 2270 children were eligible from years 1973 through 1978 - about 400 per year. Of the 2270 children, 1507 were screened at the age of 3.5 years. The authors found that visual acuity testing was unreliable, a finding which has been reported by others. (Simons K, Reinecke RD: in S_ymposium on Strabismus: Tram New Orleans Acad Ophthalmol. St Louis, CV Mosby. 1978, 15-51)

216

Surv Ophthalmol

3 I(3) November-December

1986

CURRENT

OPHTHALMOLOGY

The abandonment of stereoacuity testing was based upon about 33% of the chitdren not understanding the test. This is in sharp contrast to findings by me and my colleagues that a large percentage ofchildren pass the Random Dot Stereogram test, particularly if those who initially do not understand the test are given the opportunity to repeat the test after observing children successfully doing the test. Parenthetically, I should point out that only 22% of the children we tested in Saudi Arabia could not do the test, even when, due to a language barrier, they faced a complete lack of verbal communication with the examiner. F~lrthermore, a detailed report by Hammond and Schmidt (Hammond RD, Schmidt PP: drch ~~~t~fffr~~L fU~:54-60, 1968) documented the feasibility of using the Random Dot E test in three-year-olds and found that it compared favorably with a battery ofother tests performed by highly trained examiners. The reason to look at the RDE test carefully is its brief testing time and low cost, both of which are important aspects of screening. Another complication in Ingram’s study was that 26% of the children eventually found to have a visual problem had presented before age 3.5 years and had started treatment. The final outcome ofamblyopia treatment caused the authors to further question the benefits ofscreening. Of the 16 children followed throughout their amhlyopia treatment, only three attained a visual acuity of 6/6 (however, 8/16 attained acuity of 6/12 or better). The authors conclude that, before a national screening program is undertaken, we must have better data to justify its cost. I disagree with this conchtsion ifit is to be applied to the United States. Here, in the absence ofa national health care system, many of our children do not receive appropriate eye care, and a program of screening should be considered. The cost of poor vision in an eye of the rare child who eventually loses the other eye is astonomical. Ingram’s study is important, hut More their conclusions arc accepted, their data must be replicated by other investigators, and even then NY must e\.aluate this data carefully. I certainly concur with the authors that a test which could he done at one year ofage would he far superior to one done at age 3.5 years. Perhaps the refraction test the authors advise for one-year-olds is the answer, or even a modification of the stereo-card proposed by Lang. (Lang ,J: .Ued P! e_vg G:2206--2210, 1985) In the immediate future, I feel that we should follow the policy statement of the American Academy of Ophthalmology, Infant .4nd Children’s Eye Care, which states in part “The .American Academy of Ophthalmology strongly endorses the concept of early screening and treatment of eye and visual problems of infants and children.” (Available from: AAO. Suite 300, 655 Beach St., San Francisco, CA 94109) RC)IXKTI>.RICINIXX~;, M.D. PtifI..\l,~~l.l~t-ir.~. P~;SNS\.I,\~.wIA

Check Ligaments: Surgical Effects in Infantile Esotropia, Can J Ophthalmol21:7-9, 1986

by L.P. Noel and W.N. Clarke.

In a prospective randomized study the authors compared the results of surgical treatment of 25 patients with infantile esotropia using bilateral medial rectus muscle recession of a graded amount without severing the check ligaments. The results were compared with a similar group of 23 patients in whom check ligaments were severed at the time of bimedial surgery. No significant difference could be found in the immediate postoperative and six-month postoperative alignment of the two groups. The authors conclude that there is no difference in the reoperation rate when check ligaments are severed or spared. Surgically sparing the check ligament certainly simplifies the procedure and has the added advantage that, should a suture break during surgery or in the early postoperative stage, the medial rectus would be less likely to retract out of Tenon’s cuff’. We have not noted a difference in the amount of subconjunctival injection or hemorrhage between the two groups, nor in the amount of conjunctival scarring. (Author’s address: Dr. L.P. Knowle, Department of Ophthalmology, Children’s Hospital of Eastern Ontario, 401Smyth Road, Ottawa, Ontario, KfH8LI)

Comment It is of merit that the authors did a prospective study comparing the results of surgery following cleaning (severing) of the check ligaments to surgery done for congenital esotropia in which the check ligaments were not cleaned. They conclude that the reoperation rate was the same in both groups, and that surgically sparing