Study population and study design
This cross-sectional, comparative study consisted of 53 children aged 6-12 years who were newly diagnosed with ADHD in our university Child and Adolescent Psychiatry Department between 01.03.2020 and 01.01.2021. The Local Ethics Committee approved the study design and procedures, which were conducted in accordance with the principles outlined in the Declaration of Helsinki. Written informed consent was obtained from all participants and parents of children.
Attention deficit hyperactivity disorder was diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) criteria. Also, all children were evaluated by a child psychiatrist with a semi-structured interview to confirm the diagnosis of ADHD and to determine whether the child had any other psychiatric disorder. After the diagnosis of ADHD, these children were referred to the ophthalmology department for an ophthalmological examination. Children with pure ADHD and drug-naive, and without any ocular pathologies except refractive errors were included in the study. Patients were excluded from the study if they had mental retardation, specific learning disabilities, and autism spectrum disorders accompanying ADHD that could adversely affect visual examinations. Additionally, children with ptosis, strabismus, corneal and lens opacities, retinal abnormalities, and refractive errors beyond limits measurements according to manufacturers' recommendations were excluded. All of the patients underwent a complete ophthalmic examination, including pupil reactions, Hirschberg's test, cover-uncover, alternate cover tests, slit-lamp biomicroscopy, and dilated fundus examination.
Measurements
The refraction measurements of 106 eyes of 53 children were obtained in the same semi-lit room and the following order, and an average of three consecutive measurements for each device was recorded. Firstly, without cycloplegia, PlusoptiX A12 (Plusoptix GmbH, Nuremberg, Germany), Spot Vision Screener (Welch Allyn, Skaneateles Falls, NY), and Retinomax K-plus Screen (Righton, Tokyo, Japan) were performed respectively. Then, cycloplegia was induced by using cyclopentolate 1% (Sikloplejin; Abdi İbrahim, Istanbul, Turkey) eye drops two times with an interval of 5 minutes. After 45 minutes, pupillary light reactions were checked, and complete cycloplegia was accomplished. The cycloplegic measurements were performed by Tonoref II (Nidek Co. Ltd, Gamagori, Japan). The accuracy of the cycloplegic refractive measurements in children via table-mounted autorefractometers has been demonstrated previously 9, 10.
We also evaluated the amblyogenic risk factors according to the American Association for Pediatric Ophthalmology and Strabismus (AAPOS) referral criteria for ages > 48 months, published in 2013 11.
PlusoptiX A12 (Plusoptix GmbH, Nuremberg, Germany)
PlusoptiX A12 is a hand-held photorefractor, particularly for infants, children, and uncooperative patients, to measure refractive errors without cycloplegia. The device provides measurements of both eyes simultaneously within one second from a one-meter distance. The device uses sound and lights for fixation target and measures pupil size, interpupillary distance, and ocular alignment. Besides, Plusoptix offers a referral recommendation for ophthalmologic examination based on pre-determined referral criteria 8 . The device has a measurement range from -7.0 to 5.0 D for both spherical and cylindrical measurements.
Spot Vision Screener (Welch Allyn, Skaneateles Falls, NY)
The Spot Vision Screener is a hand-held photorefractor that provides measurements of both eyes simultaneously within two seconds from a distance of 1 meter without cycloplegia. The Spot Vision Screener uses random LED visual patterns and audible sound for fixation target and provides a report including pupillary diameter, eye alignment, and estimated refraction errors. The Spot Vision Screener also gives a warning for referral a complete eye examination according to the preprogrammed referral criteria 6 . The device can make spherical measurements at a range of -7.50 to 7.50 D and cylindrical measurements at a range of -3.00 and 3.00 D.
Retinomax K-plus Screen (Righton, Tokyo, Japan)
The Retinomax K-plus Screen is a portable, hand-held autorefraction keratometer with a 3.5-inch monitor. The device provides a monocular measurement of refractive errors from a distance of 5 cm. Retinomax is both an autorefractor and a keratometer and uses a fogging mechanism to control accommodation 12. The device also provides a quick mode in which measurements are taken in one second, and a melody is played to catch children's attention. The constantly changing color screen inside and outside of the device involves children in the examination throughout the process. The device can make spherical measurements at a range of -20.0 D to 23.0 D and cylindrical measurements at a range of 0 D to ±12 D
Tonoref II (Nidek Co. Ltd, Gamagori, Japan)
Tonoref II is an automatic non-contact tonometer and autorefractometer. The device is mounted on the table, and the patients' forehead must be placed on the forehead of the device to take measurements. The measurement range of the device is from -30.00 to +25.00 D for spherical and from 0 D to ±12 D for cylindrical measurements.
Study outcomes
Spherical, cylindrical, cylindrical axis, and spherical equivalent (SE) measurements acquired from four devices were evaluated. While calculating SE with [sphere+(cylinder power/2) ] formula, the cylindrical and axis components were transformed into vectorial representations due to the problems related to the analysis of the astigmatic component in the traditional form with the following formulas 13:
Jackson cross-cylinder at axis 0°: (J0) = (-[cylinder (D)/2] cos [2 × α]);
Jackson cross-cylinder at axis 45°: (J45) = (-[cylinder (D)/2] sin [2 × α]).
The C and α represent the negative cylindrical value, and axis in the radians, respectively. The J0 value identifies the powers at 90° and 180°. Negative J0 values indicate against-the-rule astigmatism, whereas positive J0 values indicate with-the-rule astigmatism. The J45 value defines oblique astigmatism. Positive J45 values identify the astigmatic component at 135°, and negative values do so at 45°.
Statistical Analysis
The normality of the data was evaluated with the Kolmogorov-Smirnov test. Age and refractive measurements were presented as mean ± standard deviation. Categorical variables were stated as number (n) and percentage (%). The difference between measurements was assessed by the one-sample t-test. About 95% confidence interval of the difference between the compared methods was also calculated. Bland-Altman plot was used to evaluate the agreement between devices, and 95% limits of agreement (LoA) were determined for spherical equivalent, J0, and J45 values. Reliability was analyzed by using the interclass correlation coefficient (ICC). Based on the 95% confidence interval, reliability was divided into four groups as follows: values less than 0.5 as low, between 0.5-0.75 as moderate, 0.75-0.9 as good, and higher than 0.9 as excellent reliability. Data obtained in the study were analyzed using Statistical Package for the Social Science software version 20 (IBM, SPSS 20 for Windows. Armonk, NY, USA). A value of p<0.05 was considered statistically significant.