Silverstein Evan, Lorenz Sylvia, Emmons Kathy, Donahue Sean P
Department of Ophthalmology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
J AAPOS. 2009 Feb;13(1):45-50. doi: 10.1016/j.jaapos.2008.08.011. Epub 2008 Oct 31.
To describe our experience using the Welch Allyn SureSight (Welch Allyn, Inc., Skaneateles Falls, NY) when vision screening a large population of preschool children. Additionally, we explore the usefulness of altering referral criteria to create high specificity for remote field screening in instances in which over-referral is costly.
Preschool children were screened for amblyogenic factors with the SureSight. Referred children received a gold standard examination with American Association for Pediatric Ophthalmology and Strabismus Vision Screening Committee-established failure criteria. Referral criteria were made increasingly more stringent to lower the rate of referral, and the effect on positive predictive value (PPV) was determined.
A total of 15,749 children were screened, with reliable screening obtained in >99%. Rowatt-modified Vision in Preschoolers Study referral criteria produced a referral rate of 7.3% and a PPV of 48.2%. The PPV was >70% for children with unreliable screenings and with estimated refractive errors exceeding the instrument's range. Altering referral criteria improved PPV until referral rate reached 4% (PPV approximately 64%); further refinement past this level did not increase PPV and, hence, inappropriately limited sensitivity.
A good test instrument should have high PPV and a referral rate approaching the population disease. Although altering referral criteria to decrease referral rate also decreases sensitivity, it should improve PPV. The presence of an asymptotic limit to PPV means additional improvement in PPV cannot be obtained with this technology. Thus, SureSight's usefulness for high-specificity screening is limited; however, the current referral criteria are sufficient for large screening programs and provide an acceptable referral rate and PPV.
描述我们在对大量学龄前儿童进行视力筛查时使用伟伦SureSight视力筛查仪（伟伦公司，纽约州斯卡奈特勒斯福尔斯）的经验。此外，我们探讨在转诊成本过高的情况下，调整转诊标准以提高远视力筛查特异性的实用性。
使用SureSight视力筛查仪对学龄前儿童进行致弱视因素筛查。被转诊的儿童接受了符合美国小儿眼科与斜视学会视力筛查委员会制定的失败标准的金标准检查。转诊标准逐渐变得更加严格以降低转诊率，并确定其对阳性预测值（PPV）的影响。
共筛查了15749名儿童，其中超过99%的筛查结果可靠。Rowatt修改后的学龄前儿童视力研究转诊标准产生了7.3%的转诊率和48.2%的PPV。对于筛查结果不可靠且估计屈光不正超过仪器范围的儿童，PPV大于70%。调整转诊标准可提高PPV，直到转诊率达到4%（PPV约为64%）；超过此水平进一步细化并不会增加PPV，因此不适当地限制了敏感性。
一个好的检测仪器应该有高PPV且转诊率接近人群疾病发生率。虽然调整转诊标准以降低转诊率也会降低敏感性，但应该会提高PPV。PPV存在渐近极限意味着无法通过该技术进一步提高PPV。因此，SureSight视力筛查仪在高特异性筛查方面的实用性有限；然而，目前的转诊标准对于大型筛查项目来说是足够的，并提供了可接受的转诊率和PPV。
