Clinical and demographic profile of pediatric cataracts among Omani children presenting to a tertiary eye care center, Oman

Abstract

CONTEXT:

This study aimed to know the clinical and demographic profile of pediatric cataracts in Oman.

AIMS:

The aim of this study was to describe the demographic and clinical profile of pediatric cataracts in a tertiary care hospital, Oman.

SETTINGS AND DESIGN:

This was a hospital-based, retrospective observational study.

SUBJECTS AND METHODS:

A retrospective cross-sectional study of all Omani children presented to ophthalmology outpatient at a tertiary hospital, between January 2012 and December 2016. All patients aged <18 years presented with lens opacity were included in the study. Traumatic cataract cases were excluded from the study.

STATISTICAL ANALYSIS USED:

SPSS version 22.0 International Business Machines, (Armonk, New York, Unites States of America, dated 8/13/13) used for statistical analysis.

RESULTS:

Among 379 eyes of 239 patients, 58.6% (140 patients) had bilateral cataracts. Male-to-female ratio was 1.38:1. We arrived at prevalence of 4.32 with 95% confidence interval (3.85, 4.77) of congenital cataract cases/10,000 Omani Children. Most patients (54%) were from either Muscat (28.9%) or A’Sharqiyah (25.1%). The median age of cataracts first noticed by parents was 3 months and the median age of presentation to the eye care unit was 15 months. Patients with positive family history significantly (P = 0.007) presented with bilateral cataracts (75%). About 22.2% of the patients had associated systemic diseases. Among those with systemic association, 77.4% of cases had bilateral cataracts. About 35.4% of eyes had another ocular association. The most common ocular association was squint (11.1%). The most common cataract morphologies at presentation were 20.1% presenting with total lens opacities and 19.8% with posterior subcapsular/posterior lenticonus.

CONCLUSIONS:

A higher demographic distribution of pediatric cataracts was found in Muscat governorate. There was a significant median delay in presentation to the pediatric ophthalmology clinic by 12 months since lens opacity was first noticed by parents.

Introduction

Sultanate of Oman is a Middle Eastern Nation located in the Arabian Peninsula. It has a population of 4.4 million of which 2.4 million were Omanis remaining are comprised expatriates. Forty-three percentage of Omani population is comprised children (<18 years). It has a net population growth rate of 2.29, with a birth rate of 22.11 births/1000 population.[1] The population of Oman grew from less than half a million in 1950 to more than 4 million in 2015 and is expected to reach 7 million by 2055.[2] There is a very high prevalence of consanguineous marriages in Oman, as more than half (52%) of marriages are consanguineous.[3]

Pediatric cataract is one of the main priorities of global initiatives to reduce avoidable blindness in children. It can cause devastating and irreversible complications as it occurs during a crucial phase of the development of the visual system.[4] In addition to that, it can be a huge burden socially and financially, in terms of rehabilitation for families and societies at large, especially in developing countries.[5] Therefore, studying the prevalence and epidemiological characteristics of pediatric cataract in a specific region are crucial for developing effective prevention strategies, policy making, and allocation of resources on an evidence-based manner. Thus, allowing for early identification of the disease and intervention to prevent irreversible vision loss.

Pediatric cataracts can either be acquired or congenital, with most of the cases being congenital with a percentage of more than 90%.[6] Acquired cataracts can be due to metabolic, iatrogenic, or traumatic causes.[7] Meanwhile, congenital cataract (CC) is a well-known term used when a lens opacity is detected at birth or very early in childhood.[8] It can be as a result of various causes such as genetics, syndromes, intrauterine infections, or idiopathic.[7,8,9]

Although several studies regarding the demography and morphological types of CC have been published worldwide, there are not enough studies conducted in the Middle Eastern Region and no data are currently available in Oman. The primary objective of the study was to describe the clinical and demographic profile of pediatric cataract cases among Omani population presenting to an Al Nahdha Hospital (ANH). We have estimated the disease morbidity burden by estimating prevalence. However, estimating prevalence was not the main objective. Our study was the first such study in Oman.

Subjects and Methods

This study was approved by an Institutional Research Ethics Committee and follows the guidelines of the Declaration of Helsinki. A retrospective descriptive study was conducted among all Omani children between January 2012 and December 2016, at ANH, Muscat. ANH is a tertiary hospital; it houses one of the first and pivotal ophthalmology departments in Oman. Thus, it receives referrals from all regions in Oman and it has a population of patients that resembles the diverse Omani population. ANH caters to around 70% of all pediatric ophthalmology cases in Oman. It receives referrals from all regions in Oman and it has a population of patients that resembles the diverse Omani population. The study included all patients aged <18 years with any type of lens opacity who presented to the pediatric ophthalmology outpatient department between January 1, 2012, and December 31, 2016. Children who are non-Omani, aged ≥18 years, and/or with traumatic cataracts were excluded from the study. The study investigated the following demographic variables: sex, region, age at which the cataract was first noticed by parents and age at which the child was brought to the hospital. In addition, to the studying the following epidemiological factors: laterality, morphology (such as total, lamellar, anterior polar, posterior, sutural, nuclear, or other) and etiology (such as idiopathic, prenatal infection, hereditary, metabolic, or complicated) and the associations between them. Furthermore, the association between pediatric cataracts and the following factors was explored: prematurity, family history, systemic disease (dermatological, cardiological, neurological, auditory, or others), and the presence of other ocular associations (such as squint and nystagmus or corneal disorders). Data were retrieved from the hospital information system.

Results

Three hundred and seventy-nine eyes of 239 patients were found to have cataracts. Assuming this tertiary care facility being the biggest in the country with 70% of cases presenting to it. During the study period, the population of Omani's in Oman was 2,462,768. Of them, 32.1% (790,548) of them being children <18 years. ANH caters to almost 70% of Omani pediatric ophthalmology cases in Oman. Remaining being catered to by 2 other pediatric ophthalmology units. Hence, we arrive at a prevalence rate of 4.32 with 95% confidence interval (CI) (3.85, 4.77) CC cases/10,000 Omani children from our study.

Out of the total patients, 138 (58%) were males and 101 (42%) were females with a male-to-female ratio of 1.38:1. Furthermore, 58.6% of the patients (140) had bilateral cataracts, while 41.4% (99) had unilateral cataract.

There was a diffuse geographical distribution of patients with cataracts among the different regions of the Sultanate. Most patients in the study around 28.9% were from the capital city of Oman, Muscat, with most cases being Urban. While 25.1% of cases were from A’Sharqiyah and 18.8% were from Al Batinah. However, the study of regional distribution was not the objective of our study.

The median age at which cataract was first noticed was 3 months old (3 days–15 years), whereas the age of presentation to the ophthalmology department was 15 months (7 days–16 years). Out of 379 eyes which were found to have cataracts, 245 eyes were operated. The median age at operation was 1.5 years (1 month–20 years).

About 92.9% (221 patients) of children in our study were full-term born while 7.1% (17 patients) of them were preterm.

The majority denied any family history of cataracts with a percentage of 78.1% (185 patients). Those patients who had a positive family history were only 21.9% (52 patients), out of them, 75% had bilateral cataracts with a statistical significance of P = 0.007, as shown in Table 1.

Table 1.

Relationship between family history and laterality of cataract

	Laterality		Total, n (%)	P
	Unilateral	Bilateral
Positive	13	39	52 (21.9)	0.007*
Negative	85	100	185 (78.1)
Total, n (%)	98 (41.4)	139 (58.6)	237 (100)

*Statistically significant if P<0.05. Fisher's exact test

The total number of patients who had an associated systemic disease was 53 (22.1%) patients, out of those 23 patients (43.4%) had neurological system involvement, making it the most affected. Majority of patients (69.8%) who had an associated systemic disease had bilateral cataracts, as shown in Table 2.

Table 2.

Relationship between cataract and systemic associations

	Laterality		Total, n (%)	P
	Unilateral	Bilateral
Dermatological	0	1	1 (1.9)	0.892*
Cardiological	2	6	8 (15.1)
Neurological	8	15	23 (43.4)
Auditory	1	2	3 (5.7)
Others	5	13	18 (34.0)
Total, n (%)	16 (30.2)	37 (69.8)	53 (100)

*Statistically significant if P<0.05. Fisher's exact test

Out of 379 eyes in our study, 134 (35.3%) had another ocular manifestation, the most common was squint with 42 eyes (11.1%), followed by corneal disorders with 37 eyes (9.8%), as resulted in Table 3.

Table 3.

Distribution of eyes with cataracts based on the presence of other ocular manifestations

	Frequency (%)
Squint	42 (11.1)
Lids	5 (1.3)
Cornea	37 (9.8)
Iris	13 (3.4)
Retina	8 (2.1)
Glaucoma	5 (1.3)
Others	24 (6.3)
None	245 (64.6)
Total	379 (100)

Table 4 shows the distribution of eyes with cataracts in terms of etiology, 245 eyes (64.6%) had an idiopathic etiology, 101 eyes (26.6%) with cataracts were hereditary, and only 6 eyes (1.6%) had a prenatal infection etiology.

Table 4.

Distribution of eyes with cataracts based on etiology

	Frequency (%)
Idiopathic	245 (64.6)
Hereditary	101 (26.6)
Secondary	7 (1.8)
Metabolic	5 (1.3)
Complicated	15 (4.0)
Prenatal infection	6 (1.6)
Total	379 (100.0)

In our study, 20.1% (76 eyes) had total cataracts, while 19.8% (75 eyes) had posterior subcapsular/posterior lenticonus cataracts. About 19.5% (74 eyes) had nuclear cataracts. The different morphological types of cataracts in our study are represented in Table 5.

Table 5.

Distribution of eyes with cataracts based on morphology

	Frequency (%)
Total	76 (20.1)
Lamellar	51 (13.5)
Anterior polar	53 (14.0)
Posterior lenticonus/posterior polar/posterior subcapsular	75 (19.8)
Sutural	14 (3.7)
Nuclear	74 (19.5)
Other	36 (9.5)
Total	379 (100.0)

Discussion

Pediatric cataract has a reported prevalence ranging from 1 to 15/10,000 children. The wide range reflects differences in populations, age groups, methods of ascertainment, and case definitions.[10] In 2016, a systematic review of 4 of 20 studies worldwide by, about the prevalence and incidence of CC. This study found a median prevalence of childhood cataracts to be 1.03/10,000 (range 0.32–22.9/10,000 children). In our hospital-based study, we had a prevalence rate of 4.32 with 95% CI (3.85, 4.77) CC cases/10,000 Omani children.

The median age at which cataract was first noticed by parents was 3 months, whereas the median age of presentation to pediatric ophthalmology services was 15 months. There was a significant median delay in presentation by 12 months since lens opacity was first noticed by parents. While in a study of the Australian population of pediatric cataracts,[11] approximately half of the patients were diagnosed in the 1^st year of life. While in a study conducted in France showed the average age of diagnosis was 19.7 months.[11] The median age at presentation in our study lies in between the developing and developed countries. This highlights the issue of delayed presentation of these children to pediatric ophthalmology services or could be related to the improper evaluation of leukocoria or other important signs of pediatric cataracts in primary care. Reduced awareness among the general public about the disease entity could be one of the important factors for delayed presentation as well. Once referred to tertiary care, no delay in treatment initiation was observed.

Our study showed a male preponderance, with male-to-female ratio of 1.38–1. Similar male preponderance was noticed in a Nepalese study, which showed male-to-female ratio of 1.3–1.[12] While the study from France showed male-to-female ratio of 1.12–1.[11] In our study, there was no difference in gender access to health facilities was noted.

Regarding laterality, 58.6% of the patients had bilateral cataracts, while 41.4% had unilateral cataracts in our study. Only 22.1% of our cases had an associated systemic association. We noted the majority of patients (69.8%) with associated systemic disease were having bilateral cataracts. Neurological system association was the most common (43.4%) among them. Similar results were noted in a Pakistan study which found 80.4% of their cases having bilateral CC.[9] In France-based study found 71% of their cases had bilateral CC and only 22% of their cases had systemic abnormalities, while 27% of their cases had an associated ocular abnormality.[11] While microcornea (28.3%) was the most common ocular association in the Nepal study. In our study, 35.3% of cases had another ocular abnormality, 11.1% of cases had associated squint while 9.8% (37 eyes) of cases had corneal disorders with microcornea being the most common.

While 4 out of 5 of our cases were healthy with no other systemic association and 2 of 3 did not have any associated ocular anomaly. This implies the importance of a thorough screening for all healthy children during national immunization visits for good red fundal reflexes. This could help to prevent any aspect of developmental delay of children due to visual impairment.

Around 22% of our cases had a positive family history of another family member being affected with CC. Three of every four cases with a positive family history were found to have bilateral CC. Consanguinity (69.6%) was found to be an important risk factor for CC, especially bilateral cataracts in a Pakistani study.[9] In the Australian study, more than 18% had a positive family history of cataracts. With most of the patients with positive family history having bilateral cataracts.[11] Both the above studies showed findings similar to our results.

In our study, the most common etiological cause for cataracts was found to be idiopathic (64.6%). Similar etiological cause was found in studies in the West like study in France[12] showed idiopathic cataract accounting for 63% of their patients. While studies from low-income countries showed high incidence of infectious etiology for CC. In Nepal study,[11] maternal infection was found as the major cause of CC in 17.4% of cases with predominantly congenital rubella infection in 13% of cases. Risks for idiopathic etiologies need to be explored thoroughly, which cannot be done in descriptive studies like ours.

In our study, we found that the most common morphological variety of cataracts were total cataracts, posterior subcapsular/posterior lenticonus, and nuclear cataracts. With each of these, morphological variants comprising almost 20% each. Fourteen percentage of our cases were anterior polar cataracts and 110.5% were lamellar cataracts. While in a study conducted in Nepal,[11] lamellar cataract (51.3%) was the most common morphology of cataracts observed.

Geographically, in our study, the regional distribution of childhood cataracts was highest in Muscat and A’Sharqiyah followed by Al Batinah, with the following percentages, respectively, 28.9%, 25.1%, and 18.8%. This can be explained by the higher number of populations in these regions compared to other regions in the country; As the total population, percentages in Muscat, Al Batinah, and Al Sarqiyah regions account for 21.1%, 31.5%, and 15%, respectively.[13] Consanguinity is another important factor in this demographic distribution, especially in Al Sharqiyah region, where there is a very high percentage of first-degree consanguinity. In regard to the states in the country, Jalaan State, which is located in Al Sharqiyah region as well was found to be the highest State in Oman with pediatric cataract distribution accounting for 20 patients out of 239 patients (8.4%).

In our study, 26.6% of our cases were hereditary in etiology. Among Arab countries, epidemiological and genetic data regarding hereditary pediatric cataracts are lacking.[14] Western studies showed around one-third of the bilateral cases are genetic, most of which are autosomal dominant. However, the application of the same knowledge to Oman or to the surrounding countries is debatable. While dominant causes occur, the increased consanguinity and higher fertility rates (higher number of children) are expected to increase the expression of potential homozygous recessive disease. Thus, the incidence of both known and novel recessive causes for hereditary cataract needs to be studied in detail.

The findings of our retrospective descriptive study show that the clinical and demographic profile of pediatric cataracts in Oman supports most of the international studies in terms of gender distribution, laterality, systemic and ocular association as well as family history. We noted that the most common etiologies of our study were similar to the developed economies and different from the developing ones. The time of presentation to pediatric eye care services was similar to mid-income-to-high-income countries but earlier than most of the studies from low-income countries.

The results that were presented in this study are of great value as they provide better knowledge of demographic distribution of the disease. Thus, allowing early detection of the disease among high-risk groups by pediatricians and general physicians. In addition to supporting community education and family counseling as a valuable part in the management of the disease. These results will also help in patients’ educational strategies toward better visual rehabilitation of these patients.

Although this descriptive study has a large number of cases to provide important information about the demographics of pediatric cataracts in Oman, it does not provide holistic and conclusive data about the entire population as it was based on one tertiary eye care facility. Furthermore, many of the patients from Oman access eye care outside the country these cases might not have been documented in our health system. We suggest future studies covering the entire population are needed to obtain more accurate disease prevalence and also provide insight into the geographic distribution of the disease among different governorates of Oman.

Conclusions

In Oman, pediatric cataract has a prevalence of 4.32 CC cases/10,000 Omani children from our hospital-based study. Our retrospective descriptive study shows that the clinical and demographic profile of pediatric cataracts in Oman supports most of the international studies in terms of gender distribution, laterality, systemic and ocular association as well as family history. We noted that the most common etiologies of our study were similar to the developed economies and different from the developing ones. The time of presentation to pediatric eye care services was similar to mid-income-to-high-income countries but earlier than most of the studies from low-income countries. Since associated systemic conditions and ocular conditions with pediatric cataracts are less, a robust surveillance strategy is required to identify and treat the clinically significant ones at the earliest.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.