Prevalence and determinants of refractive error and related ocular morbidities among Saudi adolescence population in Riyadh, Saudi Arabia.

PURPOSE: The purpose of this study was to determine the magnitude and determinants of refractive error (RE) and related ocular morbidities among preparatory and secondary Saudi students in Riyadh.
METHODS: This study was conducted in 2017-2018 at preparatory (12-14 years) and secondary (15-18 years) schools. A "Spot Screener" was used to determine if the child passed or failed a refraction test. Fail test meant RE ≥ ± 0.50 D. Data were collected on refractive status in each eye, anisometropia, and strabismus. The type of RE was estimated and analysis was performed for an association to gender, age, and education levels. The use of spectacle while screening defined the compliance of spectacle wear.
RESULTS: The study sample was comprised of 708 Saudi students. There were 59.5% of boys. The prevalence of RE was 43.6% (95% confidence interval [CI]: 40.0, 47.3). The prevalence of RE in preparatory and secondary students was 44.5% and 43.2%, respectively. The proportion of myopia (≥ -0.5 D) and hyperopia (≥ +0.5 D) among students with RE was 82.2% and 17.8%, respectively. Family history of RE was positively associated to RE in students (odds ratio: 1.8 [95% CI: 1.3, 2.5]). The current screening initiative identified 45 (6.4%) new cases of RE who required spectacles. The compliance rate for using visual aid among students with RE was 74.6%. The prevalence of anisometropia and strabismus was 3.0% and 4.1%, respectively.
CONCLUSIONS: A high proportion of Saudi adolescence in Riyadh have RE. Periodic ophthalmic assessment and refractive services are recommended as part of school health screening initiatives. Copyright:

Introduction

The World Health Organization (WHO) estimates that there are 19 million visually impaired children under 15 years of age. Twelve million of these children have uncorrected refractive error (RE) which is the main cause of visual impairment (VI).[1] RE includes myopia, hyperopia, and astigmatism.[2] As a child ages, the refractive status changes, warranting frequent reassessment and management of RE.[3] Unfortunately, untreated VI in children can have lifelong consequences on their learning ability, academic performance, and personality.[4] Therefore, it is essential to detect and address eye disorders in children as early as possible and monitor them periodically. The WHO recommends vision screening of schoolchildren and provides them refractive services.[5]

Environmental and genetic factors affect the development of RE.[6] The interplay between genes and environment may account for a substantial proportion of the phenotypic variance.[7] The RE is the leading cause of VI in Saudi children of Riyadh.[8] The pattern of ocular disease varies from country to country and even from region to region within a country.[9] The RE ranges from 26.4% among children younger than 18 years in southern Saudi Arabia to 34.9% among 3–10-year-old children in western Saudi Arabia.[1011] This shows that overall magnitude of RE in adolescent Saudi children is high.[12]

Therefore, we evaluated the magnitude and determinants of RE, other ocular morbidities, and compliance of spectacle wear among Saudi adolescence in the Riyadh region of Saudi Arabia.

Methods

In this cross-sectional study, we included students from Saudi schools in Riyadh city, Saudi Arabia. Of the 30 total secondary Saudi schools of Riyadh, two were randomly selected: one boys’ school and one girls’ school. All preparatory and all secondary classes of these schools were listed and randomly selected three classes were visited. All students of these classes were examined. This study was conducted between December 2017 and June 2018. The institutional research and ethics board approved this study (1633-P). Written informed consent was obtained from the school authorities. Inclusion criteria were all students of selected preparatory (12–14 years old) and secondary grades (aged 15–18 years). Exclusion criteria were students who were absent on the day of screening or did not want to participate. Our team consists of an ophthalmologist, an epidemiologist, and five medical students. Medical students were trained in using the “Spot Screener” (Welch Allyn, USA). An ophthalmologist supervised the field activities. A separate room was provided by the school authorities to undertake vision screening. Demographic data such as age and gender were collected from school records. Medical students inquired about spectacle wear, contact lens usage, history of eye surgery, ophthalmic/optical consultation in the past, and a family history of RE from participants. The contact lens users were further inquired if they were using contact regularly or occasionally.

A “Spot Screener” (Welch Allyn, USA) was used for refraction test, as it is easy to handle and user-friendly, both eyes can be tested simultaneously, and the results are available in seconds. The “Spot Screener” was calibrated every day to minimize measurement bias. During measurements, it was held at a distance of 1 m from the school student. The refractive status of each eye was displayed as sphere, cylinder, and axis on device screen. A “pass” indicated that the participant had no defects or marginal RE. A “fail” indicated that the eye has a RE of ≥±0.50 D. We also assessed the visual acuity (VA) with Lea symbol chart (15-line distant vision chart) placed in the light box at 3 m away from the student and recorded his/her distance VA in LogMAR notation. The finding of Spot Screener was matched with the distance VA. If WHO grade of VI matched with severity of RE, we considered VI due to RE. Those with mismatched, like VA decreased but test result was pass (Emmetropic), were thought to have some other pathology (posterior segment pathology, amblyopia, etc.). These students were advised to consult an optometrist and/or an ophthalmologist for further eye care.

The spherical equivalent (SE) was calculated as SE = sphere + (cylinder/2). An individual's RE status was defined based on the eye with higher RE. Emmetropia was RE between <−0.5 D to <+0.5 D (diopter). Myopia was ≥−0.5 D and further graded into: low myopia (≥−0.5 to <−3 D), moderate myopia (≥ −3 D to ≤ −6 D), and high myopia (>6 D).[13] Hyperopia was RE ≥+0.5 D and further graded as: low hyperopia (≥+0.5 D to ≤+2 D), moderate hyperopia (≥+2.25 D to ≤+5 D), and high hyperopia (>+5 D).[14] Astigmatism was eye with ≥1 D cylinder. Anisometropia was difference in RE >2.50 D between eyes.[14] The functionally normal vision was ≥20/20 to ≤20/60 with pinhole correction. Moderate VI (MVI) was presenting VA of ≥20/70 to ≤20/160 in better eye. Severe VI (SVI) was presenting VA of ≥20/200 to ≤20/400 in better eye.[15]

The data were collected using a pretested data collection form. The data collected were revised, coded (code for male = 1, female = 2, mild myopia = 11, moderate myopia = 12, severe myopia = 13, low hyperopia = 21, moderate hyperopia = 22, high hyperopia = 23, and Emmetropia = 0), and transferred to the spreadsheet of an Excel® (Microsoft Corp., Redmond, WA, USA). The Statistical Package for the Social Sciences (SPSS-22) (IBM Corp., Armonk, NY, USA) was used to perform the statistical analysis. The qualitative data such as gender and type of RE were presented as frequency and percentages while the quantitative data such as age and RE in SE were presented as mean, standard deviations, and ranges. To associate the outcome whether RE present or absent to the determinants such as age, gender, grade of school, and history of RE in family, the odds ratio, its 95% confidence interval (CI), and a two-sided “P” value were calculated. P < 0.05 was considered statistically significant.

Results

We examined 708 students; 421 (59.5%) of them were boys. There were 447 (63.1%) preparatory students and 261 (36.9%) secondary students.

Total 399 (56.4%) students “passed” the refraction test (by Spot Screener). At the time of screening, the prevalence of RE in Saudi students who required spectacle prescription was 43.6% (309/708 school students) (95% CI: 40.0, 47.3). The details of RE and ocular morbidity rates are presented in Table 1. The magnitude of RE was similar between genders and in both levels of students.

Table 1

Prevalence of refractive error and related ocular morbidities in Saudi adolescence population in Riyadh

	Examined	RE present	Prevalence	95% CI	Validation OR (95% CI), P
RE in students	708	309	43.6	40.0-47.3
Gender
Male	421	174	41.3	36.6-46.0	0.8 (0.6-1.1), 0.1
Female	287	135	47.0	41.3-52.8
School grade
Preparatory	245	109	44.5	38.3-50.7	0.9 (0.7-1.3), 0.7
Secondary	463	200	43.2	38.7-47.7
Family history of RE
None	319	108	33.9	28.7-39.0	1.8 (1.3-2.5), <0.001
Siblings	389	188	48.3	43.4-53.3
Type of RE
Myopia	708	254	35.9	32.3-39.4
Hyperopia	708	55	7.8	5.8-9.7
RE in students that need visual aid as per Spot Screener	708	164	23.2	20.1-26.3
Anisometropia in students	708	21	3.0	1.7-4.2
Strabismus in students	708	29	4.1	2.6-5.6

P<0.05 is statistically significant. RE: Refractive error, OR: Odds ratio, CI: Confidence interval

There were 584 (82.5%) (95% CI: 79.7, 85.3) students with functionally normal vision and 124 (17.5%) (95% CI: 14.7, 20.3) students with MVI. Among 309 students with RE, functionally normal vision was noted in 189 (61.2%) students and MVI in 120 (38.8%). No student had SVI.

The details of visual aid-related history and health behavior regarding the use of visual aid are presented in Table 2. The compliance with spectacle wear was 74.5% (95% CI: 68.8, 80.1) among students. There were 45 (6.4%) new cases of RE or students requiring new spectacles with revised prescription (yield of screening). This implies that the existing refractive services (eye department + optical shops) had not detected/managed these students with RE and they were identified for the first time during our screening campaign.

Table 2

Determinants of refractive error and health behavior regarding the use of visual aid among Saudi adolescent population in Riyadh

	n (%)
Advised use of spectacles in past
Yes	231 (32.6)
No	477 (67.4)
Contact lens usage
Regular	33 (4.7)
Occasional	0
Not using	675 (95.3)
Past history of ocular surgery
No	699 (98.7)
Yes	9 (1.3)
Using spectacles at time of screening
Yes	172 (74.5)
No	59 (25.5)

The subtypes of RE by gender indicated that the prevalence of myopia was similar between boys and girls [Table 3].

Table 3

Refractive error subtypes among Saudi adolescence population in Riyadh by gender

	Male, n (%)	Female, n (%)	Validity (χ2, df, P)
High myopia	3 (0.7)	2 (0.7)
Moderate myopia	27 (6.4)	34 (11.8)
Mild myopia	112 (26.6)	76 (26.5)
High hyperopia	1 (0.2)	0
Moderate hyperopia	1 (0.2)	1 (0.3)
Low hyperopia	30 (7.2)	22 (7.7)
Total myopia	142 (33.7)	112 (39.0)	1, 3, 0.3
Emmetropia	247 (58.7)	152 (53.0)
Total hyperopia	32 (7.6)	23 (8.0)
Total	421 (100)	287 (100)

P<0.05 is statistically significant. df: Degrees of freedom

The subtypes of RE among preparatory and secondary students indicated that myopia was significantly greater in secondary grade students [Table 4].

Table 4

Refractive error subtypes among Saudi adolescence population in Riyadh by school grade

	Preparatory, n (%)	Secondary, n (%)	Validity (χ2, df, P)
High myopia	3 (1.2)	2 (0.4)
Moderate myopia	19 (7.8)	42 (9.1)
Mild myopia	59 (24.1)	129 (27.9)
High hyperopia	0	1 (0.2)
Moderate hyperopia	1 (0.4)	1 (0.2)
Low hyperopia	27 (11.0)	25 (5.4)
Total myopia	81 (33.1)	173 (37.4)	4.1, 2, 0.04
Emmetropia	136 (55.5)	263 (56.8)
Total hyperopia	28 (11.4)	27 (5.8)
Total	245 (100)	463 (100)

P<0.05 is statistically significant. df: Degrees of freedom

Discussion

Nearly half of the preparatory and secondary Saudi students in Riyadh, Saudi Arabia, who were included in this study had RE. Only 6.4% of these students were detected with RE for the first time. One in five students had progression of RE since last prescription and therefore needed a new spectacle prescription. The noncompliance rate for using spectacle was 25.5% on the day of examination. Variation of RE by gender and level of school grades was not significant. However, myopia was more prevalent among elderly students whereas hyperopia was more common in younger students.

In the present study, the prevalence of RE among Saudi students in Riyadh was 43.6%. This was similar to 44.1% reported by Tamimi et al.[11] and lower than 55.5% noted in Riyadh by Alsaqr et al.[12] and higher than 22% reported in rural area of Jazan region, Saudi Arabia, by Al Bahhawiet al.[16] The participants of our study and Alsaqr et al.'s study were from Riyadh, the capital of Saudi Arabia. The parents in this area were educated and seem to cause more reading and near work culture among their wards resulting in higher risk of RE. Surprisingly, Al Rowaily et al. reported a prevalence of RE of 9.8% in 2009–2010 in Riyadh.[8] The RE rates in urban and rural areas differ likely due to differences in educational attainment, near work, and outdoor activities among children in these areas.[17] While comparing the prevalence of RE among adolescent schoolchildren in the region, we noted that Oman reported myopia in 8.8% and hyperopia in 0.6% of secondary schoolchildren.[18] The secondary schoolchildren of Jordan had 19% to 20% myopia prevalence.[19] The secondary students of western Iran had as high as 29.3% myopia, 21.7% hyperopia, and 20.7% astigmatism.[20] In another province of Iran, myopia prevalence was as high as 79%.[21] The RE, mainly myopia among adolescent population of far eastern countries, is reported high. In rural China, it was 19.3%.[22] Among junior high school students of Taiwan, myopia prevalence was 78% among boys and 81% among girls in 2000.[23] The variation of RE between studies could also be due to different years of assessment or variation of assessment tools. Further studies are required to determine the changes in RE over time in schoolchildren in Riyadh.

The prevalence of RE was similar for both genders in our study. Darraj et al. and. Tamimi et al. also reported no difference of RE between genders.[1011] In contrast, Al Wadaani et al. reported higher RE in female students.[24] Gender is a known barrier for the uptake of health services, yet it did not seem to influence our study population.[25] Perhaps, educated parents and urban study site with easy access to visual aids could explain this observation. Higher RE rates in females compared to male students of higher grades could be explained by the fact that girls have an earlier growth spurt compared to boys. Studies with larger sample have confirmed higher risk among females for myopia.[26]

The prevalence of RE among preparatory and secondary students was not significantly different. Physical growth with age is a known risk factor for myopia.[227] Hyperopia declines with age.[2] In the present study, RE included both hyperopia and myopia resulting in some blunting of the association of RE to the age of students. It could also be possible that growth spurt among Saudi teens takes place in preparatory and before they reach secondary grades.

Six in ten students with RE had functionally normal vision. As these children are less likely to have negatively affected daily living due to their visual status, spectacle may not be prescribed and even compliance is likely to be lower. If the students with MVI were already wearing spectacles, a change in prescription could be required, and if detected de novo, they must be referred for a detailed ophthalmic evaluation along with prescription of visual aids.

The compliance rate was high for spectacle wear among Saudi students. This is similar to that reported by Alsaqr et al.[12] Although this high rate of compliance is encouraging, improvement is still warranted. The underlying causes of noncompliance in teenage children require further study.

Nearly half of students with RE had one family member with a similar RE. Alsaqr et al. also noted 40% of the study sample had with positive family history of RE in Riyadh.[12] This strongly favors a genetic/familial etiology of RE in the study area. Consanguinity is a known risk factor for genetic diseases and was as high as 29.7% in young Saudi population and 37.9% in the older Saudi population.[28] Thus, a positive family history is a strong indication for RE screening of their offspring. Tabbara et al. have previously advocated discouraging consanguineous marriages in public educational programs in Saudi Arabia.[29]

The prevalence of strabismus in our study was 4.1%. This was much higher than 1.9% reported by Alsaqr et al. in a population-based study in Riyadh.[12] Strabismus in hospital-based studies was unusually high at 37% in Jazan, KSA, and 38% in Dammam, KSA.[1011] Thus, it is apparent that vision screening and RE services through school health will be beneficial in identifying children with RE; it can also help in identifying ocular comorbidities.

The prevalence of anisometropia in our study was 3.0%. Alrahili et al. and Aldebasi reported a prevalence of 7.4% and 3.6% in Medina and Qassim regions of Saudi Arabia, respectively.[227] The higher rates could be due to differing definitions of anisometropia between studies. Anisometropia is a known amblyogenic factor.[30] Unfortunately, anisometropia even if detected and addressed in this age group of children could have limited impact in improving the associated amblyopia.

Gender had no effect on the prevalence of myopia in our study. This observation contrasts with observations of higher risk of myopia among females reported by Aldebasi, Alrahili et al., and Al Wadaani et al.[22724] We cannot explain the reason for this and recommend further study with a larger population among Arab population to evaluate the effect of gender among Arab population and the prevalence of myopia.

The prevalence of myopia among secondary students was higher. This further supports the recommendation to undertake annual vision screening of schoolchildren.[5] Association of myopia with as a child grows is well known.[2] Students in higher grades participate in more near work. Therefore, progression of myopia among students in higher grade is more likely and requires periodic evaluation. The prevalence of hyperopia among preparatory students was higher compared to secondary students. This further confirms that hyperopia declines with age.[2]

Limitation

The cycloplegic refraction was not used. The Spot Screener's validity as a good vision screener compared to traditional cyclopegic vision screening has been established and recommended by the American Academy of Pediatric Ophthalmology and Strabismus and the American Academy of Pediatrics.[3132]

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.