A study on refractive error in patients of Chennai city in India, using multinomial logistic regression

Introduction

Chennai is the capital of the Indian state of Tamil Nadu. Chennai is the largest commercial and industrial center of South India as well as a cultural, economic and educational center. Chennai's 2017 population is estimated at 1,04,35,000. The eye is an organ that detects light and sends signals along the optic nerve to the brain. In humans, the eye is a valuable sense organ that gives us the ability to see. It allows for light perception and vision, including the ability to differentiate between colors and depth. Although small in size, the eye is a very complex organ. The eye is approximately 1 inch wide, 1 inch deep and 0.9 inches tall. The human eye has a 200-degree viewing angle and can see 10 million colors and shades. Eyes are very important for the human body. The brain processes the raw data from the eyes to make sense of what one see's around him/her compared to one's knowledge of the world around him/her. The brain interprets what it receives from the eyes. Without our eyes and the complex processing of visual information by our brains, we would neither be able to make sense of writing, art or photos, nor understand as much as we do from limited visual information. The eye allows us to see and interpret the shapes, colors, and dimensions of objects in the world by processing the light they reflect or emit. The eye is able to detect bright light or dim light, but it cannot sense an object when light is absent. Cycloplegia inhibits the accommodative power of the eye by blocking the action of the ciliary muscle, allowing the static or objective refractive error of the eye to be measured. The best way to obtain paralysis of accommodation is to use Cycloplegic drugs like CTC, HA+T, ROP, T and T+. Cycloplegic drugs are called anticholinergic because they block the muscarinic action of acetylcholine. This action inhibits cholinergic stimulation of the iris sphincter and ciliary muscle, which results in Cycloplegia. Sensory evaluation is a special ophthalmologic procedure that may be performed in addition to the complete eye examination. Sensory evaluation will control the eye movement of 6 extra ocular muscles. The evaluation will result in fusion, diplopia, suppressions (left, right and alternate), etc., and the methods used for sensory evaluation are Randot, Titmus fly, etc. Keratometry is used to check the corneal curvature of the eyes. Keratometer is an instrument used to check the horizontal and vertical curvature of the cornea. Children who have cylindrical power would undergo keratometric test. Children who possess 44.00-45.00 in keratometric test are having normal corneal curvature and children who have other than normal range are said to have abnormal corneal curvature. Raj kumar Yadav and Upendra Kumar (2018) [1] applied multiple regression models on rural area has effect of recent past prior migrants along with current migrations. Nur Ain Abd Aziz et al. (2016) [2] applied multinomial logistic regression model on characteristics of smokers after the smoke-free campaign in the area of Melaka. Courtney Coughenour et al. (2015) [3] observed that which infrastructure was perceived as safe and most likely to be used for transportation. Yu-Chi Liu et al. (2011) [4] observed that astigmatism affects approximately three quarters of the Chinese population aged 65 years and older in Taiwan, and that with increasing age, the prevalence of astigmatism increases. Chao-Ying Joanne Peng et al. (2003) [5] applied multinomial logistic regression model to predictor on Adolescent behavioral risks at drop from the school.

Key terms

There are four common types of refractive errors:

The following are the abbreviations used in the literature:  OD is an abbreviation for Oculus Dexter, Latin for right eye from the patient's point of view. Oculus means eye.  OS is an abbreviation for Oculus Sinister, Latin for left eye from the patient's point of view.  OU is an abbreviation for Oculus Uterque, Latin for both eyes.  SPH (Sphere): Amount of lens power in dioptres required to correct near-sightedness (myopia) or far-sightedness (hypermetropia). Correction is equal in all meridians of eye.  CYL (Cylinder): Amount of lens power for astigmatism.

A cylindrical correction corrects astigmatic refractive error of the eye by adding or subtracting power cylindrically in a meridian specified by the prescribed axis. If number has minus (-) sign, it is Myopic astigmatism. If number has plus (+) sign, it is Hypermetropic astigmatism.  Axis: The lens meridian that is 90 degrees away from the meridian that contains the cylinder power. 90 degree indicates with the rule astigmatism and 180 degree indicates against the rule astigmatism.  Presbyopia is the normal aging process of the lens of the eye. It is the loss of elasticity of the lens that occurs with aging, causing difficulty focusing at close ranges. Presbyopia usually becomes significant after the age of 40.

Data description

Material and Methods

The data was entered in the MINITAB version 16.0 for evaluation. The presence of refractive error in both left and right eyes of patients was analyzed using bar chart and individual value plot. Multinomial logistic regression models were fitted to know whether the independent variables are significant and their goodness of fit were tested.

Bar char of Refractive errors

Individual value plot of Refractive errors

Multinomial Logistic Regression model

Incorporating the variables under consideration, the multinomial logistic regression model can be written in the form Age has significant effect on all types of refractive error except high hyperopia in left eye. Gender has no significant effect on all types of refractive errors in left eye.

Conclusion

From this study, we observe that a maximum number of patients are affected by Low Hypermetropic astigmatism and minimum numbers of patients are affected by high hyperopia in both the left and right eyes. We also observe that age has significant effect on the refractive error in both right and left eyes. Also we see that gender has no significant effect on the refractive error in both right and left eyes.

References

1. Raj Kumar Yadav, Upendra Kumar. A regression model approach to study the rural out migration. International Journal of Statistics and Applied Mathematics. 2018; 3(2):01-04, ISSN: 2456-1452.
2. Nur Ain Abd Aziz, Zalila Ali, Norlida Mohd Nor, Adam Baharum, Maizurah Omar. Modeling Multinomial Logistic Regression on Characteristics of Smokers after the Smoke-Free Campign in the Area of Melaka. American institute of Physics, AIP Conference Proceedings 1750,060020, 2016. doi: 10.1063/1.4954625.
3. Courtney Coughenour, Alexander Paz, Hanns de la Fuente-Mella, Ashok Singh, Multinomial logistic regression to estimate and predict perceptions of bicycle and transportation infrastructure in a sprawling metropolitan area. Journal of Public Health, December 13. 2015; 38(4):e401-e408.
4. Yu-Chi Liu, Pesus Chou, Robert Wojciechowski, Pei-Yu Lin, Catherine Jui-Ling Liu, Shih-Jen Chen et al. Power Vector Analysis of Refractive, Corneal, and Internal Astigmatism in an Elderly Chinese Population. The Shihpai Eye Study, Investigative, Ophthalmology & Visual Science, December, Copyright, 2011, 52(13).
5. Chao-Ying Joanne Peng, Rebecca Naegle Nichols, Indiana University-Bloomington, Using Multinomial Logistic Models to Predict Adolescent Behavioral Risk Journal of Modern Applied Statistical Methods, spring. 2003, 2(1).