Tent photoscreening and patched HOTV visual acuity by school nurses: validation of the ASD-ABCD protocol. (Anchorage School District- Alaska Blind Child Discovery program).

BACKGROUND: Novel objective tests of risk factors for amblyopia offer an alternative for preschool vision screening. We compared the merits of photoscreening versus portable patched acuity testing in elementary schools. Photoscreening may outperform routine acuity testing in pediatric offices; however, both have fairly good validity when performed by specialists in preschool vision screening. METHODS: School nurses performed patched HOTV surround acuity testing and two types of photoscreening (MTI and Gateway DV-S20) in a portable tent near each classroom. RESULTS: 1700 children (696 1st grade, 710 Kindergarteners and 271 special-needs pre-Kindergarten). 14% had comprehensive exams and another 65% had normal photoscreens combined with patched acuities of 20/20 or better OU. We estimate the overall sensitivity/specificity using AAPOS guidelines for the modalities to be 39%:99% for patched HOTV acuity, 77%:99% for MTI photoscreening, and 85%:98% for Gateway photoscreening. The specificity of acuity testing was particularly low in pre-K due to 33% unable to complete the test, but about 80% of initial acuity failures were able to pass with pinhole. CONCLUSION: Tent photoscreening in younger elementary school children was more sensitive and faster than patched acuity particularly in developmentally delayed pre-K children.

Predictive value of inexpensive digital eye and vision photoscreening: "PPV of ABCD".

PURPOSE: Some consumer digital cameras have short flash to lens distances (dimensions) ideal for photoscreening so we adopted them into an ongoing Alaska state wide vision screening program, the Alaska Blind Child Discovery (ABCD) Project. METHODS: Digital cameras with short flash-lens distance were employed by lay screeners trained by a DVD movie. Confirmatory eye examinations by AAPOS (American Association for Pediatric Ophthalmology and Strabismus) criteria were sought from eye doctors. RESULTS: 2900 children were screened in 62 clinics by 14 screeners. Of the 2900 screenings, 99% were readable with 6% refereed as positive for ocular pathology. The positive predictive value was estimated as greater than 80%. The per-screening image cost was less than $0.10 (10 cents) including cameras. Some screeners interpreted images similar to central reading center. CONCLUSION: Pre-literate community eye and vision photoscreening can be both valid and cost effective.

Validated portable pediatric vision screening in the Alaska Bush. A VIPS-like study in the Koyukon.

BACKGROUND: Photoscreening and remote autorefraction showed promise in the urban "Vision in PreSchoolers Study." We transported a comparative screening with confirmation program to a remote part of interior Alaska. METHODS: Eighty children from villages in the Koyukon region received onsite three-pronged vision screening followed by gold-standard confirmatory exams. Each had patched HOTV acuity, photoscreening and Suresight remote autorefraction. RESULTS: There was a high prevalence of amblyopia and vision disorders in these villages. Acuity testing was moderately valid but not useful for children under four years old. Suresight has specificity over 90 percent with sensitivity of 60 percent. Photoscreening had specificity over 95 percent and sensitivity of 70 percent and was better than Suresight for children under age four. CONCLUSION: The Welch Allyn Suresight had similar high validity in the Koyukon as in Vision in Preschoolers (VIPS) and provides immediate, onsite results. Photoscreening, particularly with commercial digital flash cameras and specific interpretation, is a cost effective screening tool particularly for younger children.

Radio-opaque modification/substitute for the wright superior oblique tendon extender for superior oblique muscle overaction strabismus.

Kenneth Wright developed a technique for graded weakening of the superior oblique by increasing the effective length of this extraocular muscle's long tendon with a piece of silicone rubber retinal encircling band commonly used by eye surgery for retinal detachment repairs. In the absence of any specific retinal bands in our Children's Hospital, the following technique was developed affording a non-invasive ability to monitor, which was less intricate than the technique so well described by Demer. We substituted the "Mini Vessel Loop" (by Maaxxim Medical or Henley International). It is an elastic smooth silicone rubber cord that is radio-opaque, and can easily be seen on X-rays and CT scans. It is not an ophthalmologic medical device but it rather is designed to loop around and identify and gently retract blood vessels and nerves in any form of surgery where needed. We demonstrated success similar to that achieved by Wright in 43 patients using these radio-opaque, silicon Mini Vessel loops.

A comparison of patched HOTV visual acuity and photoscreening.

Early detection of significant vision problems in children is a high priority for pediatricians and school nurses. Routine vision screening is a necessary part of that detection and has traditionally involved acuity charts. However, photoscreening in which "red eye" is elicited to show whether each eye is focusing may outperform routine acuity testing in pediatric offices and schools. This study compares portable acuity testing with photoscreening of preschoolers, kindergarteners, and 1st-graders in 21 elementary schools. School nurses performed enhanced patched acuity testing and two types of photoscreening in a portable tent. Nearly 1,700 children were screened during spring semester 2004, and 14% had confirmatory exams by community eye care professionals. The results indicate that one form of photoscreening using a Gateway DV-S20 digital camera is significantly more sensitive to children with significant vision problems, as well as being the most cost effective (85% specificity and only $0.11 per child). This suggests that the adaptation of photoscreening into a routine vision screening protocol would be beneficial for efficiently detecting vision problems that could lead to amblyopia.

The Receiver-Operator Curve for Flip-Card Surround HOTV in Younger School Children: Validation of a Simple Flip Card for School Acuity Testing.

BACKGROUND: The AAP vision screening guidelines are not uniformly delivered. Moderate amblyopia can be successfully treated in children 7 years of age and older. The ideal method and threshold of vision and/or acuity testing in school is not known. METHODS: 1700 students from first grade, kindergarten, and pre-kindergarten were screened with a flip-card, surround HOTV protocol with other eye patched combined with photoscreening; 234 students had "Gold Standard" confirmatory exams from which AAPOS standards were validated. RESULTS: Receiver Operator Curves were constructed by adjusting referral criteria by grade. A cutoff of 20/25 yielded fairly good (50%) sensitivity and 90% specificity for first grade and kindergarten, but many of the pre-kindergarten were unable to complete the testing. CONCLUSION: Patched surround HOTV flip-card acuity is useful in starting school children and a cut-off of 20/25 passing acuity is suggested. Pre-kindergarten are not well acuity screened due to high inconclusive rate.

Amblyopia detection by camera: Gateway to portable, inexpensive vision screening (calibration and validation of inexpensive, pocket-sized photoscreeners).

BACKGROUND: Photoscreening can allow early detection of amblyopia. The Gateway DV-S20, and similar models of miniature, digital flash cameras, have similar optical dimensions to existing photoscreeners for less than $200. METHODS: These cameras were calibrated on known, threshold amblyogenic refractive errors induced by placing minus and toric contact lenses on a normal subject's left eye. The DV-S20 was then applied to known amblyopic patients. Students under age 7 were vision screened with patched acuity and sequential photoscreeners (MTI and Gateway). RESULTS: The digital cameras and the MTI photoscreeners produced similar magnitude interpretable crescents for amblyopiagenic refractive errors. They had very similar validation with sensitivities of 80-90% and specificities of 98% for serious eye disorders in known patients and school-aged children. CONCLUSION: Combined with careful interpretation, pocket-sized, digital flash cameras provide a portable and inexpensive digital alternative for pediatric photoscreening. A category 3 CPT code (0065T) can be used for this valid, public health technique: Amblyopia Detection By Camera (ADBC).