|Year : 2017 | Volume
| Issue : 3 | Page : 179-183
Etiopathogenesis of presenile cataracts in Central Kerala: A cross-sectional observational study
R Jyothi, Sanitha Sathyan
Department of Ophthalmology, Little Flower Hospital and Research Centre, Kerala, India
|Date of Web Publication||30-Jan-2018|
Dr. R Jyothi
Department of Opththalmology, Little Flower Hospital and Research Centre, Angamaly, Kerala
Source of Support: None, Conflict of Interest: None
Aim: The aim of this study was to determine the factors responsible for the development of presenile cataracts in patients between 18 and 50 years in Central Kerala.
Materials and Methods: This cross-sectional observational study was done on patients diagnosed with presenile cataracts (age group 18–50 years) at Little Flower Hospital, Angamaly, Kerala, from March 2016 to June 2016. A detailed history including the risk factors such as residence and occupation, diabetes mellitus (DM), atopy, and thyroid disorders was taken. Cataract was graded according to the Lens Opacities Classification System III. Statistical analysis of descriptive data was done with bar charts and pie diagrams.
Results: Out of 200 participants included in the study, there were 88 males and 112 females. The mean age of the study population was 41.88 years. Pre senile cataract was associated with Diabetes mellitus in 31%, with atopy in 8.5%and with thyroid disorders in 5%of cases. Posterior subcapsular cataract (42%) was the most common type of cataract found. Total cataract was present in 23.5%. The odds of developing cortical cataract was higher in those with thyroid disorder (odds ratio (OR) = 6.97), nuclear cataract was higher in those with uveitis (OR = 6.18) and high myopia (OR = 7.97), and total cataract was higher in those with a history of trauma (OR = 8.95).
Conclusion: Apart from DM and atopy, the place of residence and occupation (and thus possibly exposure to ultraviolet radiations) is also associated with the development of presenile cataract. Posterior subcapsular cataract is the most common type of presenile cataract in Central Kerala.
Keywords: Kerala, presenile cataracts, ultraviolet radiation
|How to cite this article:|
Jyothi R, Sathyan S. Etiopathogenesis of presenile cataracts in Central Kerala: A cross-sectional observational study. Kerala J Ophthalmol 2017;29:179-83
|How to cite this URL:|
Jyothi R, Sathyan S. Etiopathogenesis of presenile cataracts in Central Kerala: A cross-sectional observational study. Kerala J Ophthalmol [serial online] 2017 [cited 2018 Sep 19];29:179-83. Available from: http://www.kjophthal.com/text.asp?2017/29/3/179/224282
| Introduction|| |
Cataract is the leading cause of blindness in the world, accounting for 47.8% of the total blindness. In Southeast Asian region which includes India, around 51% of the blindness could be attributed to cataract. Cataract is also the second major cause for visual impairment after refractive errors. Presenile cataract is defined as the occurrence of cataract before the age of 50 years. Various risk factors have been linked to the development of cataract such as diabetes mellitus (DM), hypertension, atopy, prolonged use of steroids, trauma, severe dehydration crisis, exposure to ultraviolet (UV) light, and intraocular inflammation.
There were around 7.75 million individuals whose blindness could be attributed to cataract in 2001, and by 2020, this would increase to 8.25 million. With the rising incidence of early-onset cataract, increasing interest has been observed to establish the modifiable risk factors in cataract, especially early-onset cataract. Although there have been various such studies done around the world, very few studies have been conducted in India.
The Beaver Dam Eye Study  was a study conducted in Wisconsin in a rural community in the United States in 1988 to estimate the prevalence and incidence of age-related cataract and also the etiology of age-related cataract. An important finding from the study was the association of cigarette smoking with cataract. The Blue Mountains Eye Study  was a similar study conducted in urban community of Australia which was conducted to identify the risk factors for age-related cataract formation such as dietary factors, smoking, alcohol consumption, medications, and refractive errors.
This study proposes to explore the demography and magnitude of presenile cataract in Kerala, with the aim of identifying the modifiable risk factors.
The aim of this study was to determine the factors responsible for the development of presenile cataracts in patients between 18 and 50 years in Central Kerala.
| Materials and Methods|| |
This was a cross-sectional hospital-based observational study conducted in the department of ophthalmology at a tertiary care center. Two hundred consecutive patients in the age group of 18–50 years, diagnosed with cataract and posted for cataract extraction between March 1, 2016, and June 30, 2016, and who were willing to take part in the study were included in the study. Patients who had congenital or developmental cataracts were excluded from the study.
A detailed history including the patients' age, place of residence, risk factors such as DM, asthma, skin problems, high myopia, steroid intake, thyroid disorders, past history suggestive of uveitis, history of any ocular trauma, intraocular surgeries, history of long-term drug intake, and family history of presenile cataracts were noted. Slit-lamp examination was done to classify and grade the cataract, dilated fundus examination was done in all cases, and B-mode ultrasound scan was done in indicated cases. Cataract was graded according to the Lens Opacities Classification System III. Axial length of the eye was measured using intraocular lens master. Participants were categorized as high myopia if the spherical refractive error was more than 6 diopters. Participants in whom none of the common known risk factors were observed were categorized as miscellaneous group.
The data were entered in Excel spreadsheet. Statistical analysis of descriptive data was done with bar charts and pie diagrams.
| Results|| |
Of the 200 patients studied, there were 99 males and 101 females. The mean age of the study population was 41.88 years. In both groups, majority of the patients were in the age group of 40-50 years. Eighty-one percent (162) of patients had bilateral cataracts while 19% had unilateral cataract [Figure 1].
The percentages of patients with various risk factors are shown in [Figure 2].
Thirty-eight percent (76) of the patients came in the idiopathic group. DM was found to be the most common risk factor in the study population with 62 patients (31%) having diabetes. Nearly 12.5% (25) of the study population gave a history of ocular trauma preceding the development of cataract. Seventeen patients (8.5%) gave a history of some form of atopy, out of which 10 patients were on regular inhalational steroids. Other risk factors observed were high myopia (5.5%, n = 11), thyroid disorders (5%, n = 10) and uveitis (3%, n = 6).
The most common type of cataract seen was posterior subcapsular cataract (42%, n = 84), followed by mature cataract (23.5%, n = 47), nuclear sclerosis (NS) (21.5%, n = 43), combined cataract (10%, n = 20), and cortical cataract (CC) (3%, n = 6) [Figure 3].
In eyes with primary sclerosing cholangitis (PSC), NS, CC, and combined types, diabetes was the most common risk factor while the most common risk factor in those with mature cataract was trauma [Figure 4].
|Figure 4: Risk factors associated with different morphological types of cataract|
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The proportion of patients who come in the miscellaneous category was maximum [Figure 5] and [Figure 6] in Idukki district followed by Alappuzha district. This may be attributed to the increased exposure to UV radiations in these regions, Ernakulam and Alappuzha districts being near the sea, and more number of manual laborers/outdoor workers were present in Idukki district.
|Figure 5: District-wise proportion of patients in the miscellaneous category|
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|Figure 6: District-wise breakup of proportion of patients in miscellaneous category|
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[Table 1] shows the possible risk factors in the miscellaneous group.
The odds of developing NS was more in those with uveitis (OR = 6.18) and those with high myopia (OR = 7.97) than those without these risk factors. The odds of developing mature cataract was more in those with a history of trauma (OR = 8.95). Those participants with a history of thyroid disorder have a higher odds of developing CC (OR = 6.97) [Table 2].
|Table 2: Odds ratio between the risk factors and the morphological types of cataract|
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| Discussion|| |
Although cataract accounts for 62.6% of the blindness in India, there have been very few studies analyzing the risk factors of presenile cataract in India. In our study, many risk factors were identified which may have caused the early onset of cataract. In some patients, multiple risk factors were involved.
In a study to explore the risk factors for the early onset of cataract in India by Praveen et al. conducted in western part of India, atopy was found to be the most common risk factor associated with the development of cataract, being associated with 25.6% of the cases. In our study, we found a higher association of cataract with DM. About 31% of our study population had DM. This study also found a higher odds for nuclear cataract in those with high myopia, which was similar to our study.
Some studies have reported an association between phenytoin intake and early onset of cataract., We had one case of posterior subcapsular cataract who is also a diabetic, who was on oral phenytoin for 17 years.
Seventeen patients in this study had some form of atopy (either asthma or skin lesions), among which 10 were on long-term treatment with either inhalational or systemic steroids. Similar findings were seen in various other studies.,,
Some studies have studied the possible genetic association of presenile cataract such as the study by Santhiya et al. in Regional Institute of Ophthalmology, Chennai, where members of a family with a history of presenile cataract were studied and in whom G98R mutation in CRYAA gene was found to present. In our study, there was only one patient who gave a family history of early onset of cataract.
Posterior subcapsular cataract was the most common morphological type of cataract. It was also the most common type of cataract in all risk factor groups except in trauma group, where mature cataract was the most common morphological type seen and in high myopic cataracts where NS was the most common type. Similar findings have been reported in a study conducted in Western India  and another study conducted in southern part of India. Another possible reason for the increased incidence of PSC may be the fact that PSC causes more and earlier visual impairment than other types of cataract and so the patients, being symptomatic earlier, may report for cataract surgery earlier. Hence, we may actually be overestimating the proportion of PSC in the community.
The merit of this study is the relatively large sample size representative of Central Kerala, detailed access to medical history of the patients. The limitation of this study is that, like most of the previous studies, this too was a hospital-based study. A case–control design would have provided more insights regarding the etiology and modifiable risk factors.
| Conclusion|| |
As in most of the other studies, the most common cause of presenile cataract in our study was idiopathic. Further, case–control studies are required to evaluate the cause of early onset of cataract in this category and to assess the modifiable risk factors.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2]