1. Introduction

Refractive errors are one of the most common pathologies of the organ of vision and are the main cause of visual impairment in children and adolescents [1,2,5].

The relevance of the study of refractive errors, due to the increase in their prevalence among children and adolescents, is growing [6,7,12].

One of the main reasons for the development of low vision in children and adolescents is myopia. In young children, the incidence of myopia is 6-8%, and in older children it increases to 25-30% [8,9].

Hypermetropia rarely leads to low vision, but it is what underlies the development of concomitant strabismus and amblypoia in children and adolescents [10,11].

Astigmatism is also a common refractive error. According to various authors, astigmatism of 0.5 diopters or more in different countries occurs in 9.8 – 27.2% of children [3,4].

Purpose of the study: To study the incidence of refractive errors in children and adolescents with tuberculosis.

2. Materials and Methods of Research

A survey was conducted of children and adolescents with tuberculosis aged from 1 year to 17 years who were being treated for tuberculosis at the Andijan regional anti-tuberculosis dispensary.

A comprehensive ophthalmological examination included: determination of visual acuity without and with correction, skiascopy, autorefractometry, biomicroscopy, study of binocular functions, direct and reverse ophthalmoscopy.

Clinical, biochemical, immunological, microbiological studies and examination by specialists were also carried out.

3. Results and Discussion

Out of 1690 examined children and adolescents with tuberculosis (985 boys and 705 girls) aged from 1 to 17 years, refractive errors were diagnosed in 603 (35.7%).

According to our research, myopia was detected in 292 children and adolescents with tuberculosis, which amounted to 17.3±0.9% of the total number of those examined. Boys accounted for 41.4% (121 people) and girls accounted for 58.6% (171 people) of cases.

Таble 1. Analysis of myopia incidence by age reveals the unevenness of its occurrence in individual age groups

Myopia was not observed in the age group from 1 to 3 years. In the age group of 7-9 years, the frequency of myopia increases, especially among girls from 4.6±2.2 to 14.4±2.5% (P<0.01). In the age groups of 10-14 years and 15-17 years, the frequency of myopia was 36.1±2.9% and 37.6±4.5%, respectively, and these figures were statistically significantly higher than the age group of 7-9 years (p<0.001).

Among boys in the age groups of 10-14 years and 15-17 years, the highest detection rate was noted (20.1±2.3% and 25.3±3.5%, respectively). When comparing the frequency of detection of myopia in boys and girls without taking into account age, there is also a statistically significant predominance in girls (24.2±1.6%) compared to boys (12.3±1.0%; P<0.001).

Our studies showed that moderate hypermetropia was detected in 117 children and adolescents with tuberculosis, which is 6.9±0.6% of the total number of those examined. In boys it occurred in 69 cases (7.0±0.8%), and in girls - in 48 cases or 6.8±0.9%. The frequency of detection of moderate and high hypermetropia among children and adolescents with tuberculosis is presented in Table 2.

Table 2. Detection rate of moderate hypermetropia among children and adolescents with tuberculosis

As can be seen from Table 2, moderate hypermetropia was most revealed in the age group from 1 year to 3 years and amounted to 26.3±7.1% in boys and 22.5±6.6% in girls.

In the age group from 4 years to 6 years, the incidence of moderate hypermetropia among girls (20.7±4.3%) was 1.6 times higher than among boys (12.7±2.4%).

In the age group of 7-9 years, the incidence of moderate hypermetropia was almost the same in boys (5.5±1.3%) and girls (6.0±1.7%).

In the age group of 10-14 years, the frequency of moderate hypermetropia was 1.5 times higher in boys (4.4±1.2%) than in girls (2.7±1.0%).

In the older adolescent group of 15-17 years old, the incidence of hypermetropia in boys was 1% higher than in girls - 1.7±1.2%, and amounted to 2.7±1.3%. In all age groups, the differences in indicators were statistically insignificant (p>0.05).

With hypermetropia of 3.0 diopters and above, all children presented asthenopic complaints. Children complained of a feeling of sand in their eyes, fatigue, pain in the eyes and frontal part of the head.

High degree hypermetropia, as can be seen from Table 3, was revealed in 59 children: 35 (59.3%) boys and 24 (40.7%) girls.

Table 3. Detection rate of high degree hypermetropia among children and adolescents with tuberculosis

The analysis of detection rate of high degree hypermetropia depending on age and gender showed that in the age group of 1-3 years, the rates for boys were 3.2 times higher than for girls, and amounted to 7.9±4.4% versus 2.5±2.5%. However, these differences were not statistically significant (p>0.05).

In the age group of 4-6 years, the ratio of indicators changes: in girls it is higher (9.2±3.1) than in boys (6.6±1.8), by 1.4 times, but statistically the differences are also not significant (p>0.05).

In other age groups, no statistically significant differences were found, which indicates that there is no influence of age and gender on the detection rates of high-grade hypermetropia in children and adolescents with tuberculosis.

Astigmatism is known to be a congenital condition. In some children and adolescents it may be minor, is physiological and does not interfere with normal vision.

In some children and adolescents, astigmatism can be higher than physiological values and significantly reduces distance and near visual acuity.

During the examination, we identified astigmatism in 135 children and adolescents with tuberculosis, which is 8.0±0.6% of the total number of those examined. There were 44.4% (60 people) boys, and 55.6% (75 people) girls.

In the examined children and adolescents with tuberculosis, all types of astigmatism were detected, namely: simple myopic astigmatism was detected in 38 (2.2±0.3%), complex myopic – in 22 (1.3±0.3%), simple hyperopic – in 25 (1.5±0.3%), complex hyperopic – in 17 (1.0±0.2%), mixed astigmatism was detected in 33 (1.9±0.3%).

The detection rate of simple myopic astigmatism depending on the age and gender of the examined is presented in Table 4.

As can be seen from Table 4, the detection of simple myopic astigmatism increases from 6 to 14 years; at the age of 15-17 years, this figure decreases slightly. Among girls, simple myopic astigmatism was detected almost 1.5 times more often than in boys - 3.3±0.7% versus 1.5±0.4%, respectively (P<0.01).

Table 4. Incidence of simple myopic astigmatism among children and adolescents with tuberculosis

The trends in the incidence of complex myopic astigmatism in the surveyed population (Table 5) are similar to simple ones and girls also predominate over boys by 2 times: 1.8±0.5 versus 0.9±0.3, however, the differences are not statistically significant (P> 0.05).

Table 5. Incidence of complex myopic astigmatism among children and adolescents with tuberculosis

The incidence of simple hypermetropic astigmatism in girls and boys was almost the same, both depending on age and gender and amounted to 1.4±0.4% and 1.6±0.5%, respectively (Table 6).

Table 6. Incidence of simple hypermetropic astigmatism among children and adolescents with tuberculosis

Complex hypermetropic astigmatism among boys was revealed in 0.8±0.3% of cases, among girls in 1.3±0.4% of cases, the differences are not statistically significant (Table 7). The patterns and trends in the detection of complex hypermetropic astigmatism are similar to the characteristics of other types; it should be noted that not a single case of this type of astigmatism was identified in the age group of 15-17 years.

Table 7. Incidence of complex hypermetropic astigmatism among children and adolescents with tuberculosis

The analysis of incidence of mixed astigmatism allows us to conclude that detection rates, depending on age and gender, coincide in level and dynamics with other types of astigmatism in the studied groups (Table 8). Noteworthy is the fact that girls in all age groups have higher rates, and according to the final indicators, 1.9 times more than boys (2.7±0.6% versus 1.4±0.4%).

Table 8. Incidence of mixed astigmatism among children and adolescents with tuberculosis

Decrease in visual acuity in children and adolescents with astigmatism was in all cases accompanied by asthenopic complaints. With visual stress, children noted pain in the eyes, in the forehead and temples, headache, dizziness, irritability, and fatigue. Asthenopic complaints were more often detected in girls.

Studies have shown that in children and adolescents with tuberculosis, the highest percentage of detection was simple myopic (2.2±0.3%) and mixed astigmatism (1.9±0.3%).

The incidence of astigmatism was statistically significantly higher among girls (10.6 ± 1.1%) than among boys (6.1 ± 0.8%; P < 0.001).

4. Conclusions

Thus, our results showed that the most common refractive error in children and adolescents with tuberculosis is myopia. The incidence of myopia is 17.3±0.9%. Astigmatism was detected in 135 children and adolescents with tuberculosis, which is 8.0±0.6% of the total number of those examined.

The incidence of moderate hypermetropia among children and adolescents with tuberculosis was 6.9±0.6%, and high degree hypermetropia – 3.5±0.4%.

Refractive errors are the main cause of visual impairment in children and adolescents with tuberculosis and require timely diagnosis and correction to prevent an irreversible decrease in visual acuity.