|Year : 2021 | Volume
| Issue : 2 | Page : 59-63
Comparison of photorefraction by photoscreener (PlusoptiXA12R) with autorefractometer and cycloplegic retinoscopy in children between 5 and 15 years
S. Kripa1, V Rajesh Prabu2, H Ranjini2, Parul Priyambada2, Venu Muralidhar2
1 Department of Ophthalmology, Sankara Eye Hospital, Coimbatore, Tamil Nadu, India
2 Department of Pediatric Ophthalmology and Strabismus, Sankara Eye Hospital, Coimbatore, Tamil Nadu, India
|Date of Submission||16-May-2020|
|Date of Decision||01-Mar-2021|
|Date of Acceptance||22-Apr-2021|
|Date of Web Publication||31-Jul-2021|
V Rajesh Prabu
Sankara Eye Hospital, 16.A, Sathy Road, Sivanandhapuram, Coimbatore - 641 035, Tamil Nadu, India
Source of Support: None, Conflict of Interest: None
Aim: The aim of the study is to compare the photorefraction values by photoscreener (PlusoptiXA12R, PO) with those of autorefractometer (AR) (TOPCON RM800) and cycloplegic retinoscopy (CR) in children. Methods: It was an observational cross-sectional analytical study with a sample size of 1000 eyes conducted over a duration of one year in a tertiary eye care center. Children in the age group of 5–15 years with refractive error were screened using photoscreener and AR in noncycloplegic state followed by CR. Interclass correlation and agreement were assessed for measurements taken by all three modalities. Sensitivity and specificity were analyzed. P < 0.05 was taken significant for all statistical tests. Positive likelihood ratio, negative likelihood ratio, positive predictive value, and negative predictive value were statistically analyzed. Receiver operative characteristic curve and area under the curve were plotted. Results: Refraction measurements by photoscreener had a strong positive correlation with measurements from CR and AR. Bland-Altman plots depicted the agreement for measurements taken by all three modalities. Sensitivity and specificity of values were high for photoscreener (PlusoptiXA12R) when compared with CR and AR. Conclusion: We conclude that photoscreener is a reliable alternative to AR and CR for detection of refractive error in children between 5 and 15 years of age.
Keywords: Autorefractometer, cyclorefraction, photorefraction, photoscreener
|How to cite this article:|
Kripa S, Prabu V R, Ranjini H, Priyambada P, Muralidhar V. Comparison of photorefraction by photoscreener (PlusoptiXA12R) with autorefractometer and cycloplegic retinoscopy in children between 5 and 15 years. J Clin Ophthalmol Res 2021;9:59-63
|How to cite this URL:|
Kripa S, Prabu V R, Ranjini H, Priyambada P, Muralidhar V. Comparison of photorefraction by photoscreener (PlusoptiXA12R) with autorefractometer and cycloplegic retinoscopy in children between 5 and 15 years. J Clin Ophthalmol Res [serial online] 2021 [cited 2023 Mar 24];9:59-63. Available from: https://www.jcor.in/text.asp?2021/9/2/59/322794
Photoscreening is an easy, accurate, and reliable method to detect refractive error in children. Photorefraction is a technique that can measure refractive errors without administering cycloplegic eye drops. Photoscreener offer advantages of large working distance (approximately 1 m), short examination duration and binocular measurement. Our study aims to compare photoscreener with cycloplegic retinoscopy (CR) and autorefractometer (AR).
| Methods|| |
It was an observational cross-sectional analytical study conducted on 1000 eyes of 500 children in the age group of 5–15 years with refractive error at a tertiary eye care center over a duration of one year. We compared the photorefraction values by photoscreener (PO) (PlusoptiXA12R) [Figure 1] with those of AR (TOPCON RM800) and CR. Institutional ethics committee clearance was obtained for the study. Informed consent was obtained from guardians of all children included in the study. The conduct of the study was in accordance with the Declaration of Helsinki. Exclusion criteria included children diagnosed or treated for any eye ailments other than refractive errors such as squint, ptosis, corneal ectasias, anterior, and posterior segment anomalies.
Visual acuity was recorded using Snellen's chart for distance. All children with the refractive error were thereafter screened using the techniques of photoscreener, AR, and CR. The order followed was screening by photoscreener and AR in noncycloplegic state and lastly CR. Cycloplegia was obtained using 1% cyclopentolate eye drops instilled at a duration of every 20 min and CR was done after 1 h of putting the first drop. The average of three readings was taken for each value of PlusoptiXA12R and autorefraction. The person performing retinoscopy was blinded to the results of PlusoptiXA12R and autorefraction. Sphere (S), cylinder (C), spherical equivalent (SE), and axis were calculated using all three modalities. Children with significant refractive error (As per the American Association for Pediatric Ophthalmology and Strabismus guidelines for the prescription of glasses for children) were provided with glass prescription.
| Results|| |
Thousand eyes of five hundred patients belonging to the age group of 5–15 years were enrolled in the study.
With the assumption that the procedure of cycloplegic refraction can identify 100% of refractive errors and the new procedure of photoscreener (PlusoptiXA12R) will be able to detect refractive errors with an additional 5% sensitivity, the sample size needed will be 975 eyes with 95% confidence level and 90% power, which will include 10% dropouts during the study.
Sample Size (N) =2 (Z1-α/2 - Z 1-β) 2 × P × Q/d2
Z1-α/2-95% confidence level (α error of 5%) = 1.96
Z1-β - power of study = −0.84
d - effect size = 5%
P - pooled estimate = 83%
Q - 100-P = 17%
There were 460 male eyes and 540 female eyes in the study. The mean age of the patients in this study was 10.92 ± 3.01 years ranging from 5 to 15 years. The distribution of uncorrected visual acuity is shown in [Figure 2]. Compound myopic astigmatism was found to be the most common refractive error (54%) followed by simple myopic astigmatism (22.6%) and simple myopia (19.3%)
PlusoptiXA12R, CR, and AR measurements of 1000 eyes of 500 children in the age group of 5–15 years were conducted. In our study, the mean (±standard deviation) results for S, C, Axis values and SE measured by PlusoptixA12R were 1.41 ± 1.36, −0.88 ± 0.94, 94.56 ± 73.40, and −1.85 ± 1.38, respectively, by CR were −1.33 ± l. 29, −0.79 ± 0.88, 95.30 ± 73.51, and −1.73+±1.32, respectively, and by AR (TOPCON RM-800) were 1.42 ± 1.33, −0.86 ± 0.94, 94.52 ± 73.17, and 1.86 ± 1.35, respectively.
Interclass correlation done between measurements taken by PO and CR, i.e., S power (r = 0.982; P < 0.05), C power (r = 0.961; P < 0.05), SE (r = 0.982; P < 0.05), and axis (r = 0.970; P < 0.005) showed strong positive correlation. Similarly, interclass correlation done between measurements taken by PO and AR, i.e., S power (r = 0.982; P < 0.05), C power (r = 0.970; P < 0.05), SE (r = 0.980; P < 0.05), and axis (r = 0.977; P < 0.05) showed strong positive correlation [Figure 3].
|Figure 3: Graph depicting positive correlation between PlusoptXA12R versus Cycloplegic retinoscopy and PlusoptXA12R versus autorefractometer for spherical power, cylindrical power, axis, and spherical equivalent|
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Graphical representation of agreement for the values measured by three modalities was made by Bland-Altman plots which showed agreement between S, C, and SE values measured between PO versus CR and PO versus AR [Figure 4].
|Figure 4: Bland–Altman plots depicting agreement between PlusoptiXA12R versus Cycloplegic retinoscopy and PlusoptiXA12R versus autorefractometer|
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Sensitivity and specificity were assessed for which we used the AAPOS 2013 guidelines as the cut-offs for screening. Sensitivity and specificity values obtained for S, C, axis, and SE values were high for PO versus CR and PO versus AR.
Positive likelihood ratio is >10 for S power, C power, axis, and SE for PO versus CR and PO versus AR. This shows that PlusoptiXA12R has a high likelihood of detecting patients with refractive errors. Negative likelihood ratio is <1 for S power, C power, axis, and SE for PO versus CR and PO versus AR. This shows that PlusoptiXA12R has a high likelihood of excluding patients who does not have refractive error.
Positive predictive value and negative predictive value for S, C, axis, and SE for PO versus CR and PO versus AR show high values (>80%). This shows that PlusoptiXA12R is a good photoscreener in detecting patients with refractive error.
The receiver operative characteristic curve (ROC curve) was plotted for comparing S, C, axis, and SE measurements between photoscreener, CR, and AR with true positive rate (Sensitivity) on Y-axis and false positive rate (1-Specificity) on X-axis [Figure 5]. The area under the curve (AUC) for S was 0.970, 0.963, 0.965, respectively, for PlusoptiXA12R (PO), CR , and AR, for C were 0.973, 0.946, and 0.928 for PO, CR, and AR respectively, for axis were 0.973, 0.946, and 0.928 for PO, CR, and AR, respectively, and for SE were 0.973, 0.946, and 0.928 for PO, CR, and AR, respectively. Hence, from values of AUC for PlusoptiXA12R (which is highest for PO) in all 4 ROC curves, we can infer that PO is a reliable tool for measuring the refractive error.
|Figure 5: Receiver operative characteristic curve comparing spherical power, cylindrical power, axis, and spherical equivalent measurements between PlusoptiXA12R, cycloplegic retinoscopy, and autorefractometer|
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| Discussion|| |
Uncorrected refractive error is a major cause of visual impairment in children. They are at risk of developing amblyopia due to uncorrected high ametropia or anisometropia.
Photoscreener is a potentially useful device for the detection of refractive error in children. The PlusoptiXA12R is an infrared video camera that measures the refractive status of the eye binocularly or monocularly and works on the principle of eccentric photorefraction. The handheld camera portion provides a moving light and smiling face fixation target with warble sounds and is attached to a computer screen that displays the child's picture and the findings. The camera analyses the reflected infrared light from the retina. It has a spherical and cylindrical range of – 6.00 to + 3.00 D. It automatically calculates the SE from the sphere and cylindrical measurement obtained. It also measures the pupil diameter and the interpupillary distance. Photorefraction is unique in enabling the measurement of accommodation, convergence, and pupil size simultaneously in both eyes, objectively, and remotely (typically the camera is placed 1 m from the eyes).
Our study compared the photorefraction values by photoscreener (PlusoptiXA12R) with that of AR (TOPCON RM800) and CR in children between 5 and 15 years. It is one of the few studies in India which have studied the accuracy of photoscreener in 1000 children for detection of refractive error. Majority of studies on photoscreener have been done in the age group younger than 5 years.,,, We observed that most of the patients (30%–40%) in our study were referred from school screening, who were found to have refractive error by photoscreener and referred to clinic for further evaluation. Furthermore, the study was done in the age group of 5–15 years which matched with the age group of children screened in school screening. Hence, we wanted to highlight the reliability of photoscreener in the detection of refractive error in school screening.
According to our study, the spherical power, cylindrical power, axis and SE measurements by PlusoptiXA12R photoscreener had a strong positive correlation with that of the measurements by CR and AR. Considering CR as a gold standard for the determination of refractive error, it was justified to infer that PlusoptiXA12R is a reliable tool for the detection of refractive error in children.
Our results were found comparable with the results of a similar study done by Demicri et al. in 2013. They investigated the reliability of PlusoptixS08 and Topcon AR by comparing them with CR in 235 eyes of 118 children with a mean age of 4.9 ± 2.6 years. Our study had nearly four times the population, however, we did not test for the amblyopia. Their study included more hyperopes whereas in our study, it was more myopes since the age group of their study population was younger than our study. Even though the mean age group in our study was higher, there appears no significant effect of age on PlusoptiXA12R results.
The high specificity and sensitivity for photscreener versus AR and CR indicate that it is a potentially reliable alternative for detecting refractive error in children.
Reddy et al. had done a study on the accuracy and utility of photorefraction for refractive error correction in tribal Odisha (India) school screening in 2018 which was a cross-sectional study in 5990 children. They concluded that photorefraction may be recommended for autorefraction in school screening with reasonable accuracy if verified with a satisfactory subjective correction. In our study also, significant reliability of the values obtained through photoscreener PlusoptiXA12R was confirmed.
Ugurbas et al. conducted a study to analyze amblyopia risk factors and myopia in children aged 3–11 years using photoscreener and concluded that it is a useful tool for vision screening in preschoolers and schoolers. A similar study by Mu et al., Sharma et al. and Matta et al. concluded that photoscreener is a useful tool for the detection of amblyopia risk factors in pediatric population.
We aimed to compare the reliability of photoscreener with AR and CR for detection of refractive error. Hence, although we recorded the visual acuity of all children but we did not analysed the amblyopia risk factors affecting the visual acuity. This is a limitation of our study.
Another limitation of our study is that the results of the selected cohort of children (age 5–15 years) cannot be extrapolated to the population outside this range since the children were selected in eye clinic and hence the incidence of detection of refractive error will be higher as compared with the community. Furthermore, photoscreener cannot be used for refractive error measurements beyond-6D and + 3D, has limited use in small pupils (<3 mm), has fixation problems in posterior segment pathologies, and readings are obtained only in low lighting of examination room.
| Conclusion|| |
Photoscreener is an easy and convenient way of assessing the refractive status of the eye.
We report a significant positive correlation and agreement between PlusoptixA12R, AR, and CR measurements. We conclude that it is a reliable and potentially useful alternative to AR and CR for the detection of refractive error in children.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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