Previous studies showed that children with ADHD had a higher prevalence of refractive errors such as astigmatism, hypermetropia and amblyopia, Hence, vision screening is crucial for the early detection of refractive errors and prevent amblyopia in these children [3,12,5]. In this context, this is the first study that compares the noncycloplegic refraction measurement values obtained by Spot Vision Screener, PlusoptiX A12, and Retinomax K-plus Screen, and cycloplegic values by Tonoref II in children with ADHD. Although noncycloplegic measurements of hand-held devices underestimate or overestimate the values in terms of spherical and cylindrical powers, axis, SE, J0, and J45 compared to cycloplegic measurements of autorefractometer, PlusoptiX A12 had an excellent interclass correlation with Tonoref II regarding the spherical and cylindrical powers, SE, and J45.
Studies investigating the visual function and ocular abnormalities in children with ADHD reported a higher frequency of reduced visual acuity, subnormal stereoacuity, refractive errors, convergence abnormalities, small optic discs, heterophoria, and cognitive visual problems [12]. Ocular abnormalities in ADHD were explained by various mechanisms consisting of neurological dysfunctions in cortical regions, inhibition impairment, decrease in the optic nerve's axonal volume, and balance control failure [3].
In children with ADHD, amblyopia, hypermetropia, astigmatism, and heterotropia were found 1.89, 1.82, 1.73, and 2.01 times more likely than without ones in a population based study [3]. Refractive errors may contribute to a decrease in concentration, leading to more evident symptoms of inattention and hyperactivity. Astigmatism and hyperopia affect both near and distance vision, unlike myopia, which affects only distance vision. Accordingly, astigmatism and hyperopia can affect an individual's attentional abilities more than myopia. In particular, uncorrected hyperopia and astigmatism, and amblyopia were found to be associated with reading impairment and thus academic performance [13,14]. Therefore, detecting refractive errors is also important in the differential diagnosis of learning disabilities accompanying ADHD [15].
Amblyopia is a common, preventable cause of visual impairment in children and adults with a prevalence of 1.6-3.6% and one of the associated risk factors is uncorrected refractive errors. Higher prevalences of amblyopia in ADHD were mentioned in previous studies above. Furthermore, in a recent study, it was reported that the risk of developing ADHD is higher (1.81 fold) in children with amblyopia. The relationship between ADHD and amblyopia was speculated on sharing similar predisposing factors such as developmental delay, mental retardation, and respiratory allergic diseases [16]. Although the ARF rate may differ according to study groups, in our study group, the ARF rate at 24.5% was higher than the ARF rate which is 3.6% in the general population [17].
Photoscreeners and hand-held autorefractometers have been used for screening refractive errors, and several studies were conducted to compare devices in healthy school-aged children and also some specific patient populations, including autism and intellectual disability [18,19,7]. However, there was no study comparing non-cycloplegic measurements of photoscreeners and hand-held autorefractometers with cycloplegic measurements in children with ADHD in the literature.
Teberik et al. evaluated the comparison of non-cycloplegic measurements of three different photoscreeners consist of Plusoptix A12, Spot Vision Screener, and Retinomax K-plus 3 with cycloplegic autorefractometer measurements in healthy school-aged children. They reported that Plusoptix A12 had compatible results with cycloplegic autorefractometer in all measurements, but the integration level was moderate. [7]. The accuracy of Plusoptix A12 was reported better in the myopic, astigmatic, and anisometropic eyes than hyperopic eyes due to underestimating hyperopic refractive errors [17]. Similarly, in our study, although PlusoptiX A12 underestimates hyperopia of 0.39 D, the device had an excellent interclass correlation with Tonoref II regarding the spherical and cylindrical powers, SE, and J45 in children with ADHD. The Plusoptix was found very useful compared with cycloplegic retinoscopy, especially in determining axis and cylinder power in various studies [20]. Ugurbas et al. evaluated the validity of Plusoptix S04 as a vision screening device and reported that non-cycloplegic measurements of the device are accurate for children with intellectual disability [18]. Furthermore, in a study by McCurry et al., it was reported that vision screening with Plusoptix S08 reduced the full ophthalmologic examination requirement in one-third of the screening children with autism [19].
Yilmaz et al. evaluated the comparison of Plusoptix A09 (non-cycloplegic) and Retinomax K-Plus-3 (cycloplegic) with retinoscopy (cycloplegic) in children. Both devices showed high agreement (ICC greater than 0.90 for all) with cycloplegic retinoscopy in terms of spherical power, cylindrical power, and SE. In our study, the Retinomax K-plus Screen acquired more myopic SE values compared other three devices, and the ICC showed good reliability (ICC between 0.75 and 0.90) in terms of spherical power, SE and J45. The difference between the two studies in terms of spherical values may have resulted from the inability of non-cycloplegic measurements to eliminate accommodation in our study, unlike Yılmaz et al[21]. Additionally, previous studies confirmed that non-cycloplegic measurements of Retinomax devices were inaccurate. However, under cycloplegia, Retinomax had similar accuracy compared with retinoscopy and table-top autorefractometer in terms of spherical, cylindrical, and SE values [22]. Nevertheless, in another study, non-cycloplegic measurements of Retinomax demonstrated better results than photoscreening in terms of astigmatism and similar results in terms of hyperopia [23]. Similarly, in our study, the Retinomax K-plus Screen had excellent reliability (ICC greater than 0.90) in terms of cylindrical power and J0. Akil et compared the cycloplegic and non- cycloplegic refractive measurements of Retinomax K-plus 3 and table-top autorefractokeratometer with cycloplegic retinoscopy. They found a good agreement between Retinomax and autorefractokeratometer in J0 and J45, unaffected by cycloplegia [10].
The Spot Vision Screener has demonstrated good sensitivity and moderate specificity in detecting ARFs in children with developmental disabilities [6]. Teberik et al. reported moderate integration levels between non-cycloplegic measurements of Spot and cycloplegic measurements of autorefractometer in terms of spherical, cylindrical, and SE values [7]. In another study, Spot was found with high specificity to detect refractive errors; however, the sensitivity was found low for hyperopia [24]. In our study, we found excellent reliability in terms of cylindrical power and J0. However, there was a 0.33 D myopic shift of SE compared to cycloplegic measurements. Similarly, Qian et al. indicated that Spot had a myopic shift of 0.17 D compared to cycloplegic retinoscopy. They also reported that J0 and J45 values had medium correlations with cycloplegic retinoscopy. Nevertheless, the Spot was found to strongly agree with cycloplegic retinoscopy for the refractive error and strabismus evaluation [25].
The current study is limited by small sample size, lack of cycloplegic measurements of hand-held autorefractometer, and investigation of both eyes of children. Also, not comparing devices in terms of detecting ARFs may be another limitation of the study.
In conclusion, novel vision screening programs are widely used for detecting visual problems in children. In our study, all of the hand-held devices showed excellent reliability in terms of cylindrical power and J0 and good reliability for J45. This may guide for prescribing cylindrical power and axis; however, cycloplegic measurements may be necessary for prescribing accurate spherical values. Even though all devices had advantages or disadvantages, Plusoptix A12 showed excellent reliability for detecting refractive errors in children with ADHD. The elimination of the cycloplegia requirement, remote measurement, and short examination time in these children may increase patient compliance.