The Contribution of Autorefractometry to the Diagnosis and Management of Refractive Errors in Patients Aged 6 to 18 Years Northern Benin in 2024

Introduction

Refractive errors (ametropia) encompass all situations where the eye’s optical system fails to focus the image of an object onto the retina [1]. In 2020, the World Health Organization (WHO) estimated that 88.4 million people worldwide live with visual impairment due to uncorrected refractive errors [2]. In children, the prognosis for visual impairment depends not only on the degree of refractive error but, above all, on the early intervention and quality of care [3]. Refractive errors constitute a growing global public health problem, particularly among children and adolescents. Thus, in order to improve the diagnostic accuracy of ametropias and to optimize the visual correction of patients aged 6 to 18 years, we conducted a study on the contribution of auto-refractometry in the diagnosis and management of ametropias in subjects aged 6 to 18 years in northern Benin in 2024.

Methods

This was a descriptive and analytical cross-sectional study with prospective data collection over a period from May 20 to September 30, 2024. It included patients aged 6 to 18 years who consulted at the ophthalmology department. Sampling was non-probability, with exhaustive recruitment of all subjects admitted for consultation during the study period who met the inclusion criteria.

Data were collected using an anonymous individual questionnaire through a semi-structured interview, supplemented by clinical examination and therapeutic data. For each patient aged 6 to 18 years seen for consultation, after gathering their complaints and medical history, uncorrected distance and near visual acuity was measured. They then underwent slit-lamp examination and fundus examination. Two successive automated refractions were subsequently performed: the first before any administration of cycloplegic eye drops, and the second 30 minutes after three instillations of one drop of 0.5% cyclopentolate alternating with tropicamide at five-minute intervals. Finally, a subjective refraction was performed for the patient’s optical correction. The collected data were analyzed using EPI Infos 7.2.2.6 software and then checked using Stata 15.0 for Windows. The significance threshold was set at p < 5%. This study received approval from the Local Ethics Committee for Biomedical Research of the University of Parakou (CLERB/ UP) under number 483/2024/CLERB-UP/P/SPµ/R/SA, and data confidentiality was maintained.

Results

The results were based on 208 eyes from 104 individuals included in the study.

Socio-demographic characteristics

Influence of Cycloplegia on Patients’ Refractive Profile

Variation in the power of spherical refractive errors before and after cycloplegia

Discussion

The mean age in our study was 15 ± 3 years, with a range of 6 to 18 years. This result is close to that of Zhou, et al. [4] in China, who reported a mean age of 15.23 ± 1.77 years, and Vonor, et al. [5] in Togo, who found 12.7 ± 2.9 years. However, it differs from that of Assavedo, et al. [6], who reported a mean of 9.2 ± 2 years, and from that of Czepita, et al. [7] (11 ± 3 years). This difference is due to the diversity of the study settings.

Visual impairment and headaches accounted for 63% of the complaints reported by the subjects in our series. These results were similar to those of Gbe, et al. in Côte d’Ivoire [8] and Ayed, et al. in Tunisia [9] reported 61% and 60% respectively for decreased vision and headaches. The eye pain was reported with 38% in this study, this condition is related to the subjects with strong accommodative power [10]. Hashemi, et al. also reported that eye pain was common among university students [11]. These include Assavedo, et al. [6] and Assoumou, et al. [12], who reported itching (36%) and tearing (32%) as the main complaints, respectively.

The majority of subjects (71%) in this study had good distance visual acuity ≥8/10 according to the WHO classification [13]. Paluku, et al. (81%) then Kouassi, et al. have reported 78% [14, 15]. This explains why visual acuity is not the only indicator for diagnosing refractive error. Good visual acuity does not mean the absence of refractive error. Many individuals may have apparently normal visual acuity (≥ 8/10) while suffering from mild or moderate refractive error. The prevalence of refractive errors in subjects aged 6 to 18 years at the northern benin was 91% after autorefractometry without cycloplegia. This is significantly higher than the 19% and 21% found by Assavedo, et al. in Parakou [6] and Kouassi, et al. in Côte d’Ivoire [15], respectively. This large difference can be explained by the fact that in our study, all included subjects underwent a complete ophthalmological examination, including automatic refraction regardless of visual acuity, whereas in these two other studies, only children with visual acuity ≤ 7/10 in at least one eye underwent a complete examination.

Hyperopia and astigmatism were the most frequent refractive errors, each accounting for 50% of cases. Contrary to the results of other studies [8, 12, 14, 16] where astigmatism was the most prevalent refractive error, our proportions were closer to those of Assavedo, et al. [6], who found hyperopia (42%) to be the most common, followed by astigmatism (39%).

In our series, myopia was present in 32% of cases before cycloplegia. After cycloplegia, 13% of the eyes that were myopic remained so, and the prevalence increased to 17%, representing a highly significant decrease of 15% in myopic eyes. This decrease was also noted by Wane, et al. [17] in Senegal, where the proportion of myopic individuals decreased from 62% before cycloplegia to 30% after cycloplegia. Our results differ from those of Mvogo, et al. [18] in Cameroon, who noted no cases of myopia after cycloplegia in a study of 110 eyes. This difference could be explained, on the one hand, by the sample size and, on the other hand, by the older age of the participants in their study population (35 to 45 years). The frequency of hyperopia increased from 50% before cycloplegia to 75% after cycloplegia. Wane, et al. [17] also showed in their study that the frequency of hyperopia increased from 34% to 68% after cycloplegia.

The majority of subjects therefore had latent hyperopia that became apparent after cycloplegia.

In our study, the frequency of astigmatism was estimated at 50% before cycloplegia; This frequency increased to 73% after cycloplegia. This could still be explained by the role of accommodation in masking refractive errors in children. However, Kouassi, et al. [15] found a contradictory result, with the frequency of astigmatism decreasing from 40% to 16% after cycloplegia; similarly, Jeddi, et al. [19] found no difference. These discrepancies could be explained by methodological differences and the characteristics of the populations studied in each study. Furthermore, race-related factors are among the reasons for the difference in the prevalence of astigmatism worldwide [20].

This study also allowed us to confirm that cycloplegia causes significant in the spherical equivalent, with a mean difference of 0.97 D. This result is consistent with those of Fang Gu, et al. [21] and Jeddi, et al. [19], who reported mean differences of 0.92 D and 0.79 D, respectively.

Conclusion

Our results confirm the high prevalence of refractive errors, particularly hyperopia and astigmatism, in subjects aged 6 to 18 years. Autorefractometry has proven to be a valuable tool for the initial screening of refractive errors. However, our results clearly demonstrate the need to supplement this examination with cycloplegia, particularly in young children and adolescents. Appropriate optical correction, based on measurements taken after cycloplegia, led to a significant improvement in visual acuity in the majority of subjects. This observation underscores the importance of early and appropriate management of refractive errors to prevent vision problems and optimize visual comfort and well-being in children.