Original Research
Ophthalmology & Genetics

Prevalence of Congenital Colour Vision Deficiency Among Secondary School Male Students in Almadina Almunawara, Saudi Arabia

Background and Context

Congenital colour vision deficiency (CVD) is one of the most common inherited genetic disorders worldwide. It is an X-linked recessive condition, which means males are disproportionately affected — estimated prevalence among males of European descent is approximately 8%, while rates tend to be lower in Asian, Middle Eastern, and African populations. In Saudi Arabia, studies have documented male prevalence rates ranging from approximately 2% to 5.85%, depending on the region and screening methodology employed.

Colour vision deficiency occurs when one or more of the three types of cone photoreceptors in the retina are absent or dysfunctional. Protanopia results from missing or defective long-wavelength (red) photopigments, while deuteranopia arises from abnormalities in middle-wavelength (green) photopigments. Individuals with these conditions have difficulty distinguishing between red and green hues, which can have significant implications for educational performance, career selection, and everyday safety — particularly in occupations requiring accurate colour discrimination such as healthcare, transportation, and electrical engineering.

Despite its public health significance, population-level screening programmes for colour vision deficiency remain uncommon in many Middle Eastern nations. Early identification through school-based screening enables affected students to receive appropriate support and vocational guidance. This study from the Malaysian Journal of Public Health Medicine addresses this gap by providing prevalence data from Almadina Almunawara, one of the most culturally significant cities in Saudi Arabia, which hosts a diverse expatriate population alongside its native Saudi residents.

Study Design and Methods

This cross-sectional study recruited 1,154 male secondary school students in Almadina Almunawara city using a multi-stage random sampling strategy. The researchers first selected schools randomly from the city’s educational districts, then randomly selected students within each participating school. All participants underwent visual acuity assessment using a Snellen chart prior to colour vision testing.

The primary screening instrument was the Ishihara 24-plate test, the most widely used pseudo-isochromatic plate test for red-green colour vision deficiency. Students who failed the initial Ishihara screening were subsequently evaluated with the Farnsworth-Munsell D-15 panel, which classifies the type and severity of colour vision deficiency. Demographic information including age, nationality, and educational level was collected through structured interviews. Student ages ranged from 15 to 21 years.

Principal Results

Of the 1,154 students screened, 38 (3.3%) were identified as having congenital colour vision defects. Deuteranopia was the more common type, affecting 2.3% of participants, while protanopia was found in 1.0%. This deutan-to-protan ratio of approximately 2.3:1 is consistent with the known genetic epidemiology of colour vision deficiency, where green-deficient conditions are typically more common than red-deficient ones.

A particularly notable finding was the difference in prevalence between Saudi and non-Saudi students. The prevalence among non-Saudi students (5.48%) was more than double the rate observed among Saudi nationals (2.48%). This disparity likely reflects the genetic diversity of the expatriate population in Almadina Almunawara, which includes individuals from South Asian, Southeast Asian, and other populations with varying baseline rates of colour vision deficiency. Saudi Arabia’s historically lower rates may be related to the relatively lower genetic diversity in central Arabian populations, where consanguineous marriages remain common.

Comparison With Regional and International Data

The 3.3% overall prevalence observed in this study falls within the expected range for Middle Eastern populations. An earlier study from Riyadh reported a prevalence of 2.93% among school-aged males, while colour vision screening of Saudi Arabian children in the central region found 5.85% of males affected. The variation between studies may reflect regional differences in population genetics, varying proportions of expatriate residents, and differences in the specific age groups screened.

Compared with Western populations where the male prevalence of congenital CVD ranges from 7% to 8%, the rate in Almadina Almunawara is notably lower. However, it exceeds rates typically reported in East Asian populations, where prevalence among males is often around 4–5%. African populations generally show the lowest rates, typically below 3%. These geographic variations are attributed to differences in allele frequencies at the OPN1LW and OPN1MW gene loci on the X chromosome, shaped by evolutionary selection pressures and population genetics.

Public Health and Clinical Implications

The findings support the implementation of routine colour vision screening in Saudi Arabian schools. A prevalence of 3.3% means that in a typical secondary school class of 30 male students, approximately one student would be expected to have some degree of colour vision deficiency. Many affected individuals are unaware of their condition, which can lead to difficulties in academic subjects that rely on colour discrimination, such as chemistry, biology, geography, and art.

Career guidance is another important consideration. Students with colour vision deficiency may face restrictions in certain professions, including aviation, naval services, and some medical specialties. Early identification allows school counselors to provide informed guidance and helps students make realistic career plans. Additionally, teachers who are aware of colour-blind students can make accommodations, such as using patterns and labels alongside colour coding in instructional materials.

The higher prevalence among non-Saudi students highlights the importance of inclusive screening programmes that cover all student populations. As Saudi Arabia continues to host a large and diverse expatriate community, public health policies should account for the varying health profiles of different population groups.

Limitations

This study has several limitations that should be considered when interpreting the results. First, the study was restricted to male students only, which means no data on female carriers or the rare cases of female colour vision deficiency were captured. Second, the study was conducted in a single city, and results may not be generalizable to all regions of Saudi Arabia, where population genetics can vary significantly. Third, the use of the Ishihara test, while highly sensitive for screening, may yield slightly different results compared with anomaloscope testing, which is considered the gold standard for colour vision assessment. Finally, the study did not assess the impact of colour vision deficiency on academic performance or quality of life, which would be valuable for future research.

Significance for Public Health Practice

This study contributes valuable epidemiological data on the prevalence of congenital colour vision deficiency in a Saudi Arabian population. The findings reinforce the importance of school-based screening programmes and highlight the need for awareness among educators and healthcare providers about this common genetic condition. Future studies should include female students, employ more comprehensive diagnostic methods, and assess the functional impact of colour vision deficiency on educational and occupational outcomes in the region.

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