Evidencia científica y recomendaciones sobre cribado de agudeza visual: revisión bibliográfica

Fundamentos: En los ámbitos científico e institucional existe controversia sobre cuándo recomendar la práctica del cribado visual en la población. El objetivo de este trabajo es valorar el nivel de evidencia científica que existe sobre el cribado visual para determinar si las recomendaciones existentes son o no adecuadas. Métodos: Revisión sistemática de artículos científicos consultando las bases de datos MedLine y The Cochranre Library Plus, sin restricción de fecha, en los idiomas español e inglés. Se incluyó literatura gris mediante búsqueda manual. No se hicieron restricciones respecto al tipo de estudio. Se revisaron los abstracts y en los casos necesarios los artículos completos, teniéndose en cuenta finalmente todos los artículos que incluían recomendaciones sobre cribado de agudeza visual y eliminando el resto. Resultados: Se seleccionaron 6 artículos. La mayoría de las recomendaciones realizadas por las sociedades fueron a través de guías de práctica clínica o artículos de opinión. Respecto a los diseños de los artículos científicos localizados hubo 2 ensayos aleatorios controlados, 3 ensayos no controlados y 1 estudio transversal. Conclusiones: Los estudios sobre adultos no permiten determinar que las recomendaciones realizadas por las sociedades científicas tengan una base científica sólida. En el caso de los niños, los estudios y las sociedades científicas no aclaran cuál es la edad más idónea para realizar cribado visual.

Reducing visual deficits caused by refractive errors in school and preschool children: results of a pilot school program in the Andean region of Apurimac, Peru

Background: Refractive error is defined as the inability of the eye to bring parallel rays of light into focus on the retina, resulting in nearsightedness (myopia), farsightedness (Hyperopia) or astigmatism. Uncorrected refractive error in children is associated with increased morbidity and reduced educational opportunities. Vision screening (VS) is a method for identifying children with visual impairment or eye conditions likely to lead to visual impairment. Objective: To analyze the utility of vision screening conducted by teachers and to contribute to a better estimation of the prevalence of childhood refractive errors in Apurimac, Peru. Design: A pilot vision screening program in preschool (Group I) and elementary school children (Group II) was conducted with the participation of 26 trained teachers. Children whose visual acuity was<6/9 [20/30] (Group I) and≤6/9 (Group II) in one or both eyes, measured with the Snellen Tumbling E chart at 6 m, were referred for a comprehensive eye exam. Specificity and positive predictive value to detect refractive error were calculated against clinical examination. Program assessment with participants was conducted to evaluate outcomes and procedures. Results: A total sample of 364 children aged 3–11 were screened; 45 children were examined at Centro Oftalmológico Monseñor Enrique Pelach (COMEP) Eye Hospital. Prevalence of refractive error was 6.2% (Group I) and 6.9% (Group II); specificity of teacher vision screening was 95.8% and 93.0%, while positive predictive value was 59.1% and 47.8% for each group, respectively. Aspects highlighted to improve the program included extending training, increasing parental involvement, and helping referred children to attend the hospital. Conclusion: Prevalence of refractive error in children is significant in the region. Vision screening performed by trained teachers is a valid intervention for early detection of refractive error, including screening of preschool children. Program sustainability and improvements in education and quality of life resulting from childhood vision screening require further research.

Screening Subclinical Keratoconus With Placido-Based Corneal Indices

Purpose. To assess in a sample of normal, keratoconic, and keratoconus (KC) suspect eyes the performance of a set of new topographic indices computed directly from the digitized images of the Placido rings. Methods. This comparative study was composed of a total of 124 eyes of 106 patients from the ophthalmic clinics Vissum Alicante and Vissum Almería (Spain) divided into three groups: control group (50 eyes), KC group (50 eyes), and KC suspect group (24 eyes). In all cases, a comprehensive examination was performed, including the corneal topography with a Placidobased CSO topography system. Clinical outcomes were compared among groups, along with the discriminating performance of the proposed irregularity indices. Results. Significant differences at level 0.05 were found on the values of the indices among groups by means of Mann-Whitney-Wilcoxon nonparametric test and Fisher exact test. Additional statistical methods, such as receiver operating characteristic analysis and K-fold cross validation, confirmed the capability of the indices to discriminate between the three groups. Conclusions. Direct analysis of the digitized images of the Placido mires projected on the cornea is a valid and effective tool for detection of corneal irregularities. Although based only on the data from the anterior surface of the cornea, the new indices performed well even when applied to the KC suspect eyes. They have the advantage of simplicity of calculation combined with high sensitivity in corneal irregularity detection and thus can be used as supplementary criteria for diagnosing and grading KC that can be added to the current keratometric classifications.