Hudson, A. and S. Donahue (2005).
"Review of results of pre-school vision
screening." Invest Ophthalmol Vis Sci 46: Eabstract
Purpose: Amblyopia is a common cause of vision loss and may be preventable
by early detection and treatment of its underlining etiology. The vision
in preschoolers study (VIP) recently evaluated several vision screening
instruments and found that the Welch Allyn Sure Sight had the potential
to be an effective screening instrument, providing that new referral criteria
are incorporated into the instrument. However, the VIP study performed field
testing using trained pediatric eye doctors rather than lay personnel, and
the criteria proposed for referral were determined post hoc. Thus, it is
unclear if the Welch Allyn Sure Sight can be effective when utilized by
lay screeners and with the proposed referral criteria. We evaluated the
effectiveness of the Welch Allyn Sure Sight under these conditions.
Methods: Over the past 7 years, volunteers from local Lions' Clubs have
screened over 140,000 preschool children in Tennessee for amblyopia and
other sight–threatening conditions. The participants, 2 to 5 year
old pre–schoolers, were selected and screened with the Welch Allyn
Sure Sight instrument at the local day cares, Mother’s Day Out programs,
and preschools through the Tennessee Lion’s Outreach Program by their
standard volunteer personnel. The new VIP criteria were programmed into
the Sure Sight instrument and used for referral. Referred children were
evaluated by local Optometrists or Ophthalmologists and the results of the
formal examination, including cycloplegic refraction, were forwarded to
Vanderbilt. Failure criteria were the standard criteria for "amblyogenic
factors" proposed and published by the AAPOS Vision Screening Committee.
Results: We have currently screened over 1200 children in an ongoing study.
Ninety–nine percent of the children have been successfully screen
tested. The current referral rate averages 8.0% and the reasons for referral
includes 5.3% for astigmatism,1.3% for anisometropia, 1.1% for hyperopia,
and 0.3% for high myopia. Although follow up of referred children has been
limited, the predictive value positive is averaging 50%, with a higher PPV
for suspected hyperopia and anisometropia, and a low PPV for astigmatism.
Conclusions: The Welch–Allyn Sure Site Vision Screening Instrument
has a reasonable referral rate and PPV when used in the field, provided
that the VIP referral criteria are used. Over-referrals are still a problem,
primarily because patients referred for suspected astigmatism are often
found to be normal. Further refinements of referral criteria will increase
predictive value and should be investigated.
INTRODUCTION: The prospective Vision in Preschoolers (VIP) study evaluated 11 methods of screening and proposed referral criteria for the Welch Allyn SureSight(trade mark) Vision Screener with 90% and 94% specificity. The SureSight had a higher sensitivity than most other screening techniques when these criteria were applied. We evaluated the usefulness of these criteria in a field study of healthy preschool children. METHODS: The SureSight software was altered to recommend referral using the VIP referral criteria with 90% specificity. Lions Club volunteers screened preschool children throughout Tennessee. Referred children underwent comprehensive eye examinations with cycloplegic refraction. Examination failure criteria were based upon published standards. Reanalysis using the 94% specificity criteria was then performed. Outcomes included referral rate and positive predictive value. RESULTS: The SureSight was used to screen 4,733 children, and screening was successful in 99.7% of children. The referral rate using the 90% specificity criteria was 12.2%. Most children (73%) were referred for suspected astigmatism. The positive predictive value was 30%. Using the 94% specificity criteria from the VIP study decreased the referral rate to 7.9% and substantially decreased over referral for suspected astigmatism; however, several anisometropes went undetected. Higher specificity was achieved by raising astigmatism referral criteria to 2.2 diopters while leaving the anisometropia criteria unchanged. CONCLUSIONS: The SureSight can be used successfully for preschool screening in the field provided that criteria with high specificity are incorporated into the instrument's software program. Higher rates of positive predictive value can be achieved without jeopardizing sensitivity by raising astigmatism referral criteria to 2.2 diopters.1
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