Authors:
Samer I. Alawneh, MD**
Zaid M. Dahamsheh, MD*
Ahmed E.Khatatbeh, MD**
Awni S. Alhadeed, MD*
Mohammad A. Al-droos, MD**
Zaid A. Aleyadah, MD ***
Fakhry S. Athamneh, MD**

* Rehabilitation Specialist, Department of Rrehabilitation, Royal Medical Services **Ophthalmologist, Department of Ophthalmology, Royal Medical Services
***Orthopedic Surgeon, Department of Orthopedics, Royal Medical Services

Correspondence: Samer I. Alawneh
Email : samer_alawneh@hotmail.com

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INTRODUCTION
Senile cataract is an important cause of preventable blindness, affecting 12 to 15 million persons worldwide (1). I It is estimated that 20.5 million (17.2%) of Americans older than 40 years have cataract in either eye. The number of Americans affected by cataract and undergoing cataract surgery will dramatically increase over the next 20 years. (2) Previous epidemiological studies have enumerated lower education, decreased cloud cover, use of aspirin, diets low in selected nutrients, use of cheaper cooking fuels, lower levels of antioxidant index, cigarette smoking, increased UV - B radiation and diabetes as risk factors associated with senile cataract)(3,4). Osteoarthritis (OA) is one of the most prevalent and disabling chronic diseases affecting the elderly. Its most prominent feature is the progressive destruction of articular cartilage. The management of OA is largely palliative, focusing on the alleviation of symptoms. Current recommendations for the management of OA include a combination of non-pharmacological interventions (weight loss, education programs, exercise, and so on) and pharmacological treatments (paracetamol, non steroidal anti-inflammatory drugs and so on) (5,6). Since both osteoarthritis and senile cataract are diseases of the elderly and obesity is a risk factor for OA and cataract, the aim of this study is to see whether there is a relation between cataract and osteoarthritis and to study the prevalence of cataract in OA patients in relation to age and BMI.

METHOD
This is a prospective study done between 20th November 2009 and 20th January 2010 in Royal Medical Services hospitals. Jordan. 90 patients out of 150 patients (group A ) were diagnosed as having osteoarthritis at the rehabilitation clinic, while the remaining 60 patients (group B ) did not have osteoarthritis and were included in the study as a control group. All 150 patients were between 40 and 80 years of age and had no risk factors for cataract (e.g. diabetes, eye trauma, eye surgery, topical or systemic use of steroid , etc). Body weight was measured, body mass index (BMI) was calculated and all patients were examined in the ophthalmology clinic in order to check for the existence of senile cataract and its grade, according to the Lens Opacities Classification System III (LOCS III) (7) .

RESULTS
In each group the patients were further divided according to age, into 8 groups. They were checked for the presence of significant lens opacity (grade 3 of posterior subcapslar (P2), cortical (C3) or nuclear (NC3 lens opacity) according to the Lens Opacities Classification System III. The results are summarized in Table 1.

Table 1: The prevalence of cataract in group A and group B regarding age

The prevalence of cataract in group A and group B, regarding body mass index (BMI) is summarized in Table 2.

Table 2: The prevalence of cataract in group A and group B regarding body mass index (BMI)

The criteria for obesity was in accordance with the classification of the World Health Organization (8): under weight , a BMI of less than 18.50 kg/m2; normal, a BMI of 18.50 to 24.99 kg/m2; overweight, a BMI of 25.00 to 29.99; obesity, a BMI of 30.00 to 39.99; and extreme obesity, a BMI of 40.00 or more.

As age and body mass index increase, the prevalence of cataract increases. The overall prevalence of cataract in Jordanian individuals aged between 40 and 80 years is 22.7%. There is no increase in prevalence of cataract in patients with osteoarthritis. Posterior subcapsular lens opacity was more prominent in low to normal BMI, but as BMI increases nuclear and cortical cataract become more prevalent.

Regarding ,the distribution of lens opacity the most common type of cataract was the nuclear (64.7%) followed by the cortical type (26.5%) and posterior subcapsular (8.8%). Posterior subcapsular lens opacity was more prominent in low to normal BMI, but as BMI increases nuclear and cortical cataract become more prevalent.

DISCUSSION


Figure 1: The prevalence of cataract in group A and group B regarding age


Figure 2: The prevalence of cataract in group A and group B regarding body mass index (BMI)

It is clear that the prevalence of cataract among OA patients (group A) is very close to that in group B, as shown in Figure 1. Also it is noted that as age increases the prevalence of cataract increases. The prevalence was 5.3% in patients aged between 40-49 year of age in group A and 0.0% in group B but it increased to 60.0% in patients aged between 70-79 year of age in group A and 55.6% in group B. So there is no increase in risk of developing cataract in patients with OA. The overall prevalence of cataract in Jordanian individuals aged between 40 and 80 years is 22.7% which is higher than that found in some areas of the world, for example David S. Friedman et.al.(2) have found that the prevalence of cataract in Americans older than 40 years is 17.2%. This could attributed to the use of a different classification system (Lens Opacities Classification System II(9) instead of Lens Opacities Classification System III which was used in our study. Additionally you can find a large variation in prevalence among different parts of the world(10). This difference is also due to the use of a different classification system of lens opacity and even when some studies use the same classification system they consider different grades as significant lens opacity. Geographical variation also plays a role in the prevalence of cataract due to sunlight exposure (11) and Jordan is considered one of the low cloud cover countries.

Regarding the prevalence of the cataract in group in relation to body mass index (BMI) it is also clear that the prevalence of cataract among OA patients is very close to that in group B as shown in Figure 2. Also it is noted that as BMI increases the prevalence of cataract increases. The prevalence was 6.7% in group A and 0.0% in group B when BMI was < 18.5 kg/m2 but it increased to 66.7% in group A and 50.0% in group B when BMI was between 30.0 and 39.9 kg/m2. So the difference in prevalence of cataract in both groups is not statistically significant. The increase in prevalence of cataract among obese patients could be attributed to the metabolic effect and the decreased sensitivity of the body cell to insulin despite not having diabetes. In addition to obesity may influence several physiological processes involved in cataract formation such as oxidative stress, glycosylation and osmotic stress(12). It should be mentioned that obesity is considered one of the risk factors for OA and weight reduction is one of the important treatment modalities for it(13). Like other studies (12,14)the most common type of cataract was the nuclear (64.7%) followed by the cortical type (26.5%) and the posterior subcapsular (8.8%), but unlike many studies, gender differences were statistically not significant for all types of cataract.(12) When we compare the distribution of the type of cataract regarding age there was no particular distribution in any age for all types of cataract, however when we compare the type of cataract regarding BMI, nuclear and cortical type was associated with high BMI and posterior subcapsular cataract was more prominent in individuals with low and normal BMI. This is also different from what was found by J M Weintraub et al(12) who found that Obesity increases the risk of developing cataract overall, and of PSC cataract in particular. Laura E Caulfield (14) found that both BMI and stature are independent risk factors for cataracts but Tung-Mei Kuang et al .(15) found that Body mass index is an independent risk factor for nuclear and cortical opacities . This variation suggests that geography plays a role in the development of cataract type.

CONCLUSIONS
As age and body mass index increase the prevalence of cataract increases. The overall prevalence of cataract in Jordanian individuals aged between 40 and 80 years is 22.7%. There is no increase in prevalence of cataract in patients with osteoarthritis. Posterior subcapsular lens opacity was more prominent in low to normal BMI, but as BMI increases nuclear and cortical cataract become more prevalent.

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