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Faculty of Health and Life Sciences

Degree project work

The Prevalence of Anterior Segment and Crystalline Changes in a Nicaraguan Population

Author:Georgette Nisa Subject: Level:First cycle No:2016:O20

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Prevalence of Anterior Segment and Crystalline Lens Changes in a Nicaraguan Population Georgette Nisa

Supervisor: Karthikeyan Baskaran Department of medicine and Optometry PhD, Senior Lecturer Linnaeus University SE- 391 82 Kalmar Sweden

Examiner: Peter Gierow Department of medicine and Optometry Professor, FAAO Linnaeus University SE- 391 82 Kalmar Sweden

The Examination Project Work is included in the Optometrist study program, 180 hp Abstract Aim: The purpose of this study was to find the prevalence of different ocular changes in the anterior segment of the eye and changes in the crystalline lens among Nicaraguan population. Method: The study was done during a journey to Nicaragua with the organization VFA and Synoptik that lasted for two weeks in March/April. There were a total of 134 participants with 71 females and 63 males. The average age of the study participants was 50 (±20) years and the age ranged from 7 to 97 years. The total sample size was collected in the three towns that we visited during the journey: Ticuantepe, Léon and Estéli. The changes were evaluated by direct ophthalmoscopy. was examined by asking the patients to look into different gaze directions. and crystalline lens was examined by asking the patient to look directly at the ophthalmoscope. Results: 31% out of the participants enrolled in this study were healthy with no visible ocular changes. The remaining 69% had ocular changes with majority of them having either , or . The prevalence of cataract was 24%, pterygium 20%, pinguecula 10%. There were other minor ocular changes such as in 4%, in 4%, in 1%, and in 1% seen in these participants. Conclusion: The UV related changes had the highest prevalence. This study like previous studies have shown that cataract was most prevalent ocular change in this population.

Keywords Vision For All, Ocular Changes, Cataract, Pterygium, Pinguecula, Nicaragua.

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Sammanfattning Syftet: Syftet med denna studie var att undersöka prevalensen av förändringar i ögats främre segment samt i den kristallina linsen hos befolkningen i Nicaragua.

Metod: Studien genomfördes under en resa till Nicaragua med organisationen VFA och Synoptik. Resan skedde i mars/april och varade i två veckor, där städerna Ticuantepe, Estéli och Léon besöktes. Studien hade totalt 134 deltagare från alla tre städerna varav 71 kvinnor och 63 män med en åldersspridning på 7-97 år. Bedömningen av förändringarna gjordes med hjälp av ett oftalmoskop genom att be patienterna att följa examinatorns finger med blicken på olika riktningar. För bedömning av corneala och lentikulära förändringar fick patienterna titta rakt fram på oftalmoskopet.

Resultat: 31% av deltagarna hade friska ögon utan några förändringar. De vanligaste okulära förändringar som upptäcktes i denna studie var katarakt, pterygium och pinguecula. Prevalensen av katarakt var 24%, pterygium 20% och pinguecula 10%. De andra förändringar som upptäcktes bland befolkningen var röda ögon 4%, ptos 1%, arcus senilis 4% och afaki1%. Det fanns ingen signifikant skillnad mellan män och kvinnor i de olika förändringarna.

Slutstats: Den högsta prevalens av förändringar var bland de UV relaterad förändringar. Denna studie precis som tidigare studier visar att katarakt är det mest prevalenta ögonförändringen bland denna befolkning.

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Thanks/ Acknowledgements

 I would like to thank my supervisor Karthikeyan Baskaran for all the help throughout the entire project and for his advices.

 I thank all my amazing co-travelers to Nicaragua: John Godoy, Sara Thoresson, Hege Welin, Maud Arvidsson, Jaime Hellqvist, Camilla Efraimsson, Tomas Hjalmarson, Mona Lundgren, Andreas Johansson and Åsa Mårtensson. It was such a great and memorable experience.

 I am thankful to Synoptik and VFA for making this journey and study possible

 I also want to thank my wonderful classmates for an exciting and fun three years together.

 Big thanks to my parents, siblings and the entire family for all their love, motivation and always be there for me.

 Finally I would like to thank my Fiancé and soon to be husband Armel Fungula for his support, encouragement and motivation throughout the entire study.

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Contents

1 Introduction ______1 1.1 Anatomy of the Eye ______1 1.1.1 ______1 1.1.2 Conjunctiva ______2 1.1.3 Cornea ______2 1.1.4 ______3 1.1.5 Crystalline Lens ______4 1.2 Ocular Changes ______4 1.2.1 Ptosis ______4 1.2.2 Red eye ______4 1.2.3 Pinguecula ______5 1.2.4 Pterygium ______6 1.2.5 Arcus Senilis ______7 1.2.6 Cataract ______8 1.3 Vision for All ______8 1.4 Nicaragua ______9 1.5 Previous Studies ______9

2 Aim ______11

3 Methods ______12 3.1 Patients ______12 3.2 Materials ______12

4 Results ______14

5 Discussion ______17

6 Conclusion ______20

References ______21

Appendix ______I

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1 Introduction

Changes in different parts of the eye occur gradually as we get older and they are due to different factors such as age, sicknesses, trauma, infections and exposure to UV radiation.

1.1 Anatomy of the Eye

The is divided into thirteen different parts (see figure 1). It is spherical, consists of three coats with different structures and has 24 mm as a mean diameter. The cornea and make up the outer coat, the second coat consists of the uveal tract which is made up of the iris, and the . The third and inner coat of the eye includes the , macula fovea and the (Forrester, 2002).

figure 1 Schematic diagram of different parts of the eye.

(Modified from google, .org)

1.1.1 Eyelid The eyelid is a thin skin that covers and protects the anterior surface of the eye from injury and foreign bodies. Other functions of the eyelid are regulation of the amount of light that enters the eye, distribution of tear film on the cornea during blinking and the drainage of tears. The motion of the eyelid is mostly vertical but there is also a horizontal motion of the eyelid that occurs during blinking. This enables the sweeping of the tears towards the superior and inferior puncta along the lid margin. Fibrous tissue also known as the tarsal plate make up the eyelid´s fibrous layer and this gives a firm shape to the eyelid. Because there is a more developed tarsal plate collagen

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in the upper lid, it enables the lid to be everted. The structure of the eyelid is divided into six parts: skin, subcutaneous layer, muscles, sub muscular areolar layer, fibrous layer, and palpebral conjunctiva. The eyelid has a very elastic, thin and fat free skin composed of dermis, epidermis and subcutaneous tissue. Due to the delicacy and thinness of the skin, the eyelid is susceptible to pathology. (Bergmanson, 2012, p 30).

1.1.2 Conjunctiva The conjunctiva provides a smooth surface to facilitate the sliding of the eyelid every time the eye blinks (Remington, 2005 p 170). It is a thin mucous membrane that stretches from the limbus to the margin of the eyelid and covers the eye ball (Lawrenson, 2010 p, 10). Palpebral, fornix and the bulbar conjunctiva are the three regions of the conjunctiva. The palpebral conjunctiva has many blood vessels and is attached to the tarsal; it also covers the inner eyelid. The bulbar conjunctiva covers the eye ball all the way to the limbus, it can freely move because it is loosely attached to the Tenon´s capsule. The fornix conjunctiva connects both the palpebral and bulbar conjunctiva from the transition of the eyelid to the eye ball (Kanski, 2011, p 132). The conjunctiva is an important protection of the eye because it serves as a barrier for microorganisms and foreign bodies. It is the most active immunological tissue on the outer part of the eye because it contains many immunological cells (Bergmanson, 2012, p 38).

1.1.3 Cornea The cornea is normally transparent with no muscles or blood vessels and is very sensitive due to the many nerves that are present in its stroma and epithelium. (Kanski, 2011 p 168). It protects the eye from outer influences and has approximately 42 dioptres which stands for two thirds of the eye´s total refractive power. (Lawrenson, 2010 p, 16). The central thickness of the cornea is around 0.55mm, 12 mm as the horizontal diameter and a vertical diameter of approximately 11 mm (Kanski, 2011, p 168). Epithelium, Bowman´s layer, stroma, Descemet`s membran and endothelium are the five different layers of the cornea. The epithelium is renewed frequently and has five to seven cell layers that make up 10% of the thickness. Bowman´s layer consists of irregular collagenous fibres and proteoglycans. When an injury occurs in this layer the empty space that is formed gets filled by epithelium cells because the Bowman´s layer does not get renewed.

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Approximately 90% of the corneas thickness is made from the stroma. The different parts of the stroma are the lamellae, keratinocytes and the extracellular matrix. Scarring develops when there is an injury in this layer because the new tissue that is formed after the injury is different from the original tissue (Langley & Ledford, 2008, p. 58-60) The Descemet´s membran grows and thickens from 5 μm to 15 μm throughout life. Endothelium layer is contiguous to the anterior chamber and the aqueous humour from which it gets it´s nutrient. The endothelium cell reduces by 0.6% every year and they do not get renewed. When cells in this layer die the remaining cells spread out to fill in the empty space that is created (Kanski, 2011 p 168).

1.1.4 Iris The iris is located closest to the opening and makes up a third of the entire . It is a very strong pigmented, thin and circular disk that is surrounded by the aqueous humour. The iris separates the anterior and posterior chamber angle with the help of the ciliary body and trabecular meshwork which binds it to the chamber angle. The collaret is the part that divides the iris into the inner and outer zone, it is located 15 mm from the pupillary boundary and around it is the biggest part of the iris. The iris is also divided into four different layers which are: the anterior layer, sphincter muscle and stroma, dilator muscle and the anterior epithelium and posterior epithelium. The anterior layer is in direct contact with the aqueous humour and the anterior chamber, this layer consists of collagen fibrils, fibroblast and melanocytes which produce the melanin pigment (Forrester, Dick & McMenamin, 2008, p 29). The colour of the iris and it´s pigmentation depend on how the melanocytes are arranged and it´s density. Nevus freckles are often seen in the anterior segment layer. In the stroma there are lymphocytes, mast cells, macrophages and clump cells. The clump cells are round, dark pigmented cells mostly found near the sphincter muscle. These cells are present in every eye including albinos and they increase with age. The sphincter muscle surrounds the pupil and induces pupillary as it contracts. (Remington, 2005, p 35). The anterior epithelium is built of myoepithelial cells and starts where the stroma ends. The dilator muscle is stretched from the root of the iris to the middle of the sphincter muscle. The posterior epithelium is a strong and single layer of cells that are bound together by tight junctions. Out on the iris periphery the pigmentation reduces leading the posterior epithelium to transition into the ciliary body´s non pigmented epithelial layer. (Bergmanson, 2012, p 153)

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1.1.5 Crystalline Lens From the figure 1, it is seen that the crystalline lens is located behind the iris and in front of the vitreous body. Ninety percent of the crystalline lens consists of proteins; the crystalline that is surrounded by a collagen lens capsule is a part of it (Oyster, 1999, p 492). It is a biconvex lens that consists of three layers: the lens fibres which are the innermost, the lens epithelium makes up the second layer and the third layer is the lens capsule which is also the outermost layer (Liou & Brennan, 1997). When the ciliary muscle contracts the form of the lens changes and the image on the retina becomes blurry, this process enables to take place (Remington, 2005, p 87, 89, 97). With approximately 20D, the crystalline lens is responsible for a one-third of the eye´s total refractive power (Oyster, 1999, p 491). As the crystalline lens becomes stiffer, the accommodation range and the light transmission through the lens reduces with increasing age (Ygge, 2011, p 186).

Ocular Changes

1.1.6 Ptosis Ptosis is a condition that occurs when the upper eyelid is in an unusually low in position than normal, it can be congenital or acquired later in life. It can be unilateral or bilateral depending on the etiology. One way of measuring ptosis is by measuring the palpebral height opening, normally the upper eyelid rests 2 mm below the upper limbus. Ptosis can be classified as neurogenic, myogenic, aponeurotic and mechanical. Neurogenic ptosis is caused by Horner syndrome and third nerve paresis. Low transmission of impulses at the neuromuscular junction causes myogenic ptosis. This type of ptosis is usually present in people with myasthenia gravis, myotonic dystrophy and progressive external opthalmoplegia. Defect in the levator aponeurosis causes Aponeurotic ptosis. Mechanical ptosis is developed by Scarring and gravitational effect (Kanski & Bowling, 2011, p 39). Dehiscence, disinsertion or stretching of the levator aponeurosis leads to a restricted transmission of strength from a normal levator muscle to the upper lid and that results to involution ptosis which is an age related condition. Severe ptosis (4 mm or more) can be treated with surgery. (Kanski & Bowling, 2011 p 39).

1.1.7 Red eye Red eye is a wide concept and can be a result of very many different changes and pathologies in the eye. A red eye is usually an indication of an injection of the

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conjunctiva in which can be caused by different conditions such as (see figure 2). Pathologies of different parts of the eye such as the uvea, , cornea, conjunctiva, sclera or episclera and the eyelid can all manifest as red eye. Infection, inflammation, autoimmune disease, trauma and in some rare cases secondary to tumours are among the many different original causes of red eye (Sethuraman & Kamat, 2009).

Figure 2 : Red eye

Acute red eye needs to be treated immediately because in these cases the etiology of the red eye can be threatening to the whole eye. Subconjunctival haemorrhage, conjunctivitis, trauma, toxic reaction, cornel ulcer, acute angle-closure glaucoma, and are among the different conditions that are under the category of acute red eye (Bezan et al 1999). Treatments for acute red eye vary depending on the pathology and what caused it, for example: bacteria, allergy, virus, immunology etc. (Kanski & Bowling 2011, p 135, 137)

1.1.8 Pinguecula Pinguecula is characterised by a white or yellowish elevation on the bulbar conjunctiva adjacent to the limbus. It can be located on both sides of the limbus but most commonly at the nasal than the temporal limbus (Kanski & Bowling, 2011, p 162). Pinguecula can be made of three different types of conjunctival epithelium, an atrophied, a hardened and a normal conjunctival epithelium. (Taylor, West, et al 1989) Most patients are not aware of the lesion but sometimes patients can complain about the cosmetic appearance. Pinguecula can sometimes be inflamed and cause mild irritation to the eye but is mostly asymptomatic. It usually is a result of aging and environmental factors such as exposure to UV radiation. Pingueculae does not need treatment; the

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patient can be encouraged to wear sunglasses for their protection. In some cases patients are given tear substitutes if needed (Bezan, et al 1999 p 123)

1.1.9 Pterygium Pterygium is a triangular visible disorder of the ocular surface. A fibro vascular sub epithelial from the degenerative bulbar conjunctival tissue grows over the limbus onto the cornea. It usually arises from the nasal limbus and most commonly found in men, the elderly and among the people with chronic (Denniston et al, 2014, p 207). There are different factors that contribute to the development of pterygium such as genetic attribute, lifestyle behaviours and exposure to the sun. Several studies have shown that pterygium is mostly present in people living in hot climates especially countries nearer to the equator. The geographic significance can be due to daily exposure to the sun. UV B (ultra violet B) can cause cellular changes to the limbus and cornea and that can make it a risk factor to the development of pterygia (S.M.Saw & D. Tan 1999).

Figure 3 Pterygium, modified picture from Kanski (2011, p 164)

The pterygium is made up of three parts, the cap, the head and the body. It is also divided into three different types based on its growth on the cornea. Type 1 can be seen in the corneal epithelium as it extends less than 2mm onto the cornea. Type 2 grows up to 4mm on to the cornea and Type 3 is larger, it grows more than 4mm past the cornea which also affects the visual axis. Symptomatic patients can be treated with tear substitutes, topical steroids and also advised to wear sunglasses for the reduction of exposure. When vision is affected by the pterygium growing over to the pupil it can be treated by surgery (Kanski & Bowling, 2011, p 163). There are different

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symptoms that a patient suffering from pterygia can complain of, such as irritation, , decreased visual acuity, foreign body sensation and the cosmetic disturbance that it can cause. Decreased visual acuity/ vision is a complaint that patients can have if the pterygium has grown and is affecting the visual axis (Bezan, et al 1999, p 123).

1.1.10 Arcus Senilis Arcus senilis also known as corneal arcus is one of the aging changes that occur in the cornea. It mostly develops without giving any indication of systemic conditions in elderly individuals. With age the cornea becomes more translucent due to condensation in the stroma, the Bowman´s and Descemet´s membran also become thicker. Arcus senilis is an infiltration of fat near the margin of the cornea. The fatty degeneration begins in the stroma and Bowman`s membrane. As it appears in the outer layer it normally starts as two separate white crescents, one on the superior and the other on the inferior cornea. After a while the two arcs fuse and form a band around it (Snell & Lemp 1998, p 16, 149).

Figure 4 Pterygium in the left eye.

In most cases the band is wider in the vertical than in the horizontal meridian. The central part is diffuse and the peripheral part is more clear and separated from the limbus by a clearer zone. Patients with Schnyder crystalline usually develop arcus senilis as well. (Kanski & Bowling, 2011. p.224).

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1.1.11 Cataract The crystalline lens of the eye is normally clear and cataract is a condition that occurs when the lens becomes blurry and opaque. This makes it hard for light to pass through the lens to the retina, which leads to poor visual acuity in the affected eye. Cataract may cause blindness if not treated with surgery in good time. 40% of the world´s blindness is caused by cataract and that represents 16 million people. Even though cataract is present in almost all ageing people, no access to proper eye care means that 99% of the blind cases due to cataract are found in developing countries. (Denniston et al 2014, p 302) There are two different types of , congenital and age related cataract which is the leading cause of blindness in the world (Langford-Smith et al 2016). Age related cataract is partly caused by the breaking down of the crystalline lens fibres to albuminoids that releases amino acids. These amino acids eventually change the pigmentation of the lens making it more opaque. Exposure to sunlight, specifically UV radiation contributes to the developing of cataract (Forrester, Dick & McMenamin, 2008, p 491).

Cataract development is divided into three stages. Immature cataract describes the early stage where the lens is a little opaque. Mature cataract is when the entire lens is completely opaque and the affected eye can barely see. The last stage is hyper mature cataract and in this stage there is leakage of fluid out of the lens which leads to a wrinkled and shrunken anterior capsule. Age related cataract is treated with surgery when the patient has difficulty in performing daily activities due to the opacity of the lens (Kanski & Bowling, 2011, p 271).

1.2 Vision for All

Vision for All (VFA) is an organisation that makes it possible for people in need of to be able to study, work and have a good vision. Its main goal is to work with the poor who are in great need of optometrist´s input and those who cannot afford to pay for an eye exam or buy glasses. VFA puts together glasses that are donated by people, clean and measure them before packing them. A team of opticians, optometrist and assistants take the glasses, travel to different developing countries around the world and give to the people in need (Vision for All, 2016).

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1.3 Nicaragua

Nicaragua is the largest country in Central America with a size of 148 000 square kilometres and the capital city is Managua. The country is bordered by Honduras to the north, Costa Rica to the south, the Caribbean and Pacific Ocean to the east and west. Nicaragua´s population is slightly above 6 million people. (Walker & Wade, 2011, p 1). The Caribbean and Pacific Ocean meteorological influences, altitude and mountainous land barriers are the reason the country´s climatic characteristics vary in different locations. Due to these factors the country can be divided into three different regions: the Caribbean lowlands, the western lowlands and central highlands. The Caribbean lowlands have a hot climate with humid tropical rain forests. The western lowlands and central highlands are the two regions with rich soils and moderate climate. Majority of the population live in the western lowland and there are a line of volcanoes through this region. (Walker & Wade, 2011, p 2).

1.4 Previous Studies

In 2004 a study was done in rural Nicaragua to investigate the prevalence of cataract, pinguecula, pterygium and the reported degree of caused by cataract. 1559 patients participated in the study with an age range of 1 to 90 years and a mean age of 34 years. The presence and severity of the condition was graded with a standardized grading scale. The prevalence of cataract was 12.38% and in which 50% of those with cataract had visual acuity impairment worse than 20/40. The prevalence of pterygium and pinguecula was 38.74%. There was a great rise in prevalence from age group 10-19 to 20-29 years where an increase from 6.45% to over 40% was observed (Chan et al 2004). Temperature and UV radiation is believed to accelerate the development of cataract, the main risk factor being ultraviolet radiation. Sliney (1986) did a study revealing that the most critical ocular exposure to UV B radiation is the reflectance of the radiation from the ground. 8-18% of reflectance from the sand, the soil and grass had a reflectance of 1-4%. If the eye is exposed to bright sunlight between 6-8 hours, the different levels of reflectance from the sand are enough to cause changes in the anterior segment of the eye. The study showed that landscapes with many mountains and trees had a reduced reflectance. It also showed that when the sky is a little cloudy there is a greater ocular exposure in comparison to a day when the sky is clear. This is because the eyelid is wider when it is cloudy (Sliney, 1986).

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A study done in Sydney in 1998 reported the prevalence of pterygium and pinguecula in people above the age of 49 years. They also looked at the association with skin, hair and eye colour. Among the 3564 people who were examined, 7.3% had pterygium and 69.5% had pinguecula in either eye. There were significantly more men than women who had both pterygium and pinguecula. There was a significant association found in the study between pterygium and increased pigmentation in skin and hair as well as decreased skin sun sensitivity (Panchapakesan, Hourihan & Mitchell, 1998). In central rural India a study was done to find the prevalence of corneal arcus and it´s associations. The sample was collected randomly with a size of 952 participants who were 30 years and older. The BMI of the participants was calculated and their lifestyle taken into consideration. This was done in order to see if there are any association between that and the corneal arcus. The prevalence of corneal arcus (arcus senilis) was 10.7% and there was a significant association with age observed among those people. There were no associations found with smoking, arterial hypertension, diabetes mellitus and alcohol consumption. (Vurgese S, et al 2011). A previous study was done as an examination project work in Nicaragua 2011. The aim of the study was to find the prevalence of UV related changes among the people who were seeking help. Different factors such as age, sex and environment were examined to see if there was any correlation with the prevalence of the changes in the eye. There was total of 1180 patients form ages 4-96 participated from three different towns, Léon, Estéli and Octal. The study showed that cataract had a prevalence of 7%, pterygium was 12% and pinguecula had a prevalence of 6%. It also showed that pterygium and pinguecula was more common among men. The occurrence of pterygium and cataract increased with age. In the majority of the people with pterygium and pinguecula it was observed that the placement of these changes was mostly nasal than they were temporal. (Sandberg,2011).

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2 Aim

The purpose of this study was to find the prevalence of changes in the crystalline lens and in the anterior segment of the eye among the Nicaraguan population.

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3 Methods

All the data in this study was collected in Nicaragua during a journey that was organised by Vision for All and sponsored by Synoptik. This took place in a two week period from 2016-03-25 to 2016-04-06. Different cities and towns were visited during this period where the study was conducted for a total of 10 days. The first three days were spent in Ticuantepe, a small town 13 km south of the capital city, Managua. The journey continued to Estéli which is located 800m above sea level north of the capital city and has approximately 100 000 inhabitants. The measurements were done there for three days. The last four days of the study took place in the city of Léon and it is located in the west coast of Nicaragua. Léon is located 20 km inland from the Pacific ocean.

3.1 Patients

The patients that took part of the study were people who came for help regarding their sight after receiving information that the organisation Vision For All was coming to their town. Before participating in this study the patients needed to have an eye examination. They also need to have a piece of paper with their name, age and occupation as well as the information of their visual acuity and refractive power. (Appendix1). The patients were selected among the people who came for help. There was no particular order conducted while selecting the participants. There was no age limitation for the patients to be able to participate in the study and that led to an age range of 7-97 years with (±20) as the standard deviation. The number of participants in this study was 134 patients out of which there were 71 females and 63 males.

3.2 Materials

An ophthalmoscope is the instrument that was used to detect and evaluate the different changes that were present in the anterior segment of the eye and the crystalline lens. The monocular indirect ophthalmoscopy procedure is done to view the retina without having to dilate the pupil. (The procedure can also be performed in young children, patients who have difficulty with tolerating binocular technic due to the bright light and for basic screening. (Elliott,2007). )

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This procedure was chosen for this study because it is fast and easy to perform. An ophthalmoscope is easily portable and can be readily used for screening procedures. During the screening the patient was asked to first look straight ahead and the magnification of the instrument was adjusted in order for the anterior segment and crystalline lens to be seen clearly. After looking straight ahead the patient had to follow the examiner´s finger by moving the eye towards the direction of examiners finger in four positions of gaze (left, right, up and down). As the participant looked at different directions the examiner moved the ophthalmoscope looking for any unusual ocular changes. After the screening the examiner documented the findings. When there was no ocular change it was documented as a healthy eye and if there was an ocular change, the type of change along with the participant’s age and gender was documented.

figure 5: Eye screening in Estéli

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4 Results

In total there were 134 participants that took part in our study and the majority of them (70%) were between the ages 70 to 90 years. The mean age of the participants were 50 (±20) years with an age range from 7 to 97 years. The majority of the study participants had varying degrees of ocular changes present in their eye. The ocular changes that were present are as follows: cataract, pterygium, pinguecula, ptosis, arcus senilis, aphakia, swollen , posterior capsule opacity, red eye and blindness. These changes were present in either one or both eyes with the majority having binocular changes. The participants were grouped in different categories. If they had no ocular changes they were documented as healthy otherwise they were grouped according to the finding. Ocular changes such as swollen eyelid and posterior capsule opacification was coded as other ocular changes. There were more females than males in the healthy category and more males than females in the pterygium categories but there was no great difference in gender distribution among the remaining categories. (Figure 6).

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N 25 u m 20 b e 15 r

10 o Male f Female 5 p

0

e Healthy

Cataract Pinguecula

Arcus Aphakia

Blind Ptosis

Others Pterygium Red eye

o

p

l

e Different Changes

figure 6 The distribution of gender among the different ocular changes.

On presentation, 41 (31 %) participants did not have any visible ocular changes in their anterior segment of the eye. The total prevalence of different changes was 69%.

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The prevalence of cataract was 24%, among those who had cataract 53% were women and 47% men. Out of the people who had cataract 25% had mature cataract that affected their daily life activity due to the poor vision. The prevalence of Pterygium was 20% of the patients and among those patients 59% were male and 41% female. Pinguecula had a prevalence of 10%.

Prevalence of red eye and ptosis was 4% and 2%, in this category the majority with these changes were male. Red eye was mostly seen in the age group 51-60 years old and ptosis appeared in patients who were 60 year or more. Blindness and aphakia was equal between male and females with the prevalence of 3% and 1%. Blindness was equally divided in the different age groups while aphakia was more common between the ages of 71-80. Arcus senilis had a prevalence of 4% and among those who had arcus 40% were between 61-70 years. (see figure 7). Changes such as swollen eyelids and posterior capsular opacity are included in the other category.

Blind Ptosis Aphakia Others 3% 2% 1% 1% Arcus 4%

Red eye Healthy 4% 31% Pinguecula 10%

Pterygium 20% Cataract 24%

figure 7 The Prevalence of changes found in the anterior segment of the eye.

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Cataract, pterygium and pinguecula were the most frequent of all the changes noted during this study.

Diagramrubrik 14 N u 12 m b 10 e r 8 o Cataract f 6 Pterygium

Pinguecula p 4 e o 2 p l 0 e 0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-99

Age groups

figure 8 Cataract, pterygium and pinguecula represented in the different age group

The majority of people with cataract were in the age group 61-70 years. Pterygium was most seen among age groups 31-40 and 51-60 years. There were more males than females who had pterygium. Among those who had pterygium 61% had it located on the nasal side. In the age group 41-50 years were the most people with pingueula represented.

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5 Discussion

Out of all the participants, 69% had one or several changes in the anterior segment of the eye. This high prevalence can be due to the fact that the sample was collected from a screening camp where people came to seek help. Majority of them had already noticed problems with their eyes or vision. If the sample was randomly collected from a nonclinical environment for example by knocking from door to door the prevalence would most likely be lower.

The most common ocular changes in this population were cataract, pterygium and pinguecula. The exposure to UV radiation could be a major factor for these ocular changes to occur. This is expected in Nicaragua because of its location, climate and temperature. According to a study done in North America (Sliney, 1989) being exposed to sunlight for a couple of hours a day is enough to cause changes in the anterior segment of the eye. These UV related changes showed a high prevalence from age of 45 years and more. The majority of participants in that age group were people who worked outside as farmers, street sellers, carpenters etc., and were exposed to sunlight almost daily.

In this study the prevalence of cataract was 24% and with changes occurring at the age of 50 years with a peak prevalence around the age of 60 to 70 years. The percentage of prevalence in this study is twice the result that was reported in a study done in rural Nicaragua. (Chan et al, 2004). Chan et al reported the prevalence of cataract was 12% with the peak prevalence in the age group 70-79 years. They had a sample size of 1559 participants in their study. A previous student work done in Nicaragua (Sandberg, 2011) showed the prevalence of cataract to be 7% with a peak prevalence in the age group of 80- 89 years, which was much lower than both Chan et al (2004) and our study. This study had 1 180 participants while the current study had only 134 participants. The higher prevalence of cataract in our study can be attributed to lower sample size of the study. This current study had a lower sample in comparison to the other studies because there was only one person doing the screening meanwhile the other studies had several examiners.

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The high prevalence of cataract cannot be extrapolated to the entire population because of our relatively small sample size and due to the fact that data was collected in participants who were seeking help.

The prevalence of pterygium and pinguecula were also reported by Chan et al (2004) and Sandberg (2016) for this population. Chan et al reported a combined prevalence of pterygium and pinguecula to be 38% and Sandberg reported a prevalence of pterygium and pinguecula to be 18,7%. In our study the combined prevalence of pterygium and pinguecula was 30% and the results compare well with findings of Chan et al. It is also reported in this study that most of the people with pterygium were males and it was mostly located on the nasal side. In order to get a more accurate and reliable prevalence data it is important to get a large sample that can give a significant representation of the entire population in that country or area. The Sandberg study (2011) had a lower prevalence of cataract, pterygium and pinguecula in comparison to the Chan et al and this study. This can be due to the majority of the participants (52%) in Sandberg study were between the ages 40-59 years who were younger than the people recruited for our study and Chan et al (2004) study.

Ptosis, arcus senilis, blindness, aphakia and red eye are the other changes that were found in this study but there were no previous prevalence studies related to these changes.

It is recommended that studies should also look at other ocular changes such as ptosis, arcus senilis and blindness apart from the ocular changes related to exposure of UV radiation in the future.

Out of 41 participants who were healthy with no ocular changes, the majority were females. Most of the female participants were housewives or worked as housekeeper and did not get exposed to UV radiation as much as the men who worked away from home did. Most of the male participants worked as farmers, street sellers, carpenters or in factories. The difference in working places could be a reason as to why there were more ocular changes in men than women. However there was no big difference between men and women among the participants.

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An ophthalmoscope was the instrument used for the evaluation of changes in this study and it is a good screening instrument which was convenient for the study. A biomicroscope would have facilitated the evaluation of the changes by enabling a more detailed view. With the help of a biomicroscope the cataract and red eye changes could have been graded using different grading scales. The slit lamp was not used in this study because it would have been difficult and not practical to carry it around to the different locations.

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6 Conclusion

The results from the study showed that prevalence of cataract was highest followed by the prevalence of pterygium and pinguecula in the Nicaraguan population. However, due to small sample size and the population examined came to seek help the prevalence of ocular changes cannot be extrapolated to the entire Nicaraguan population.

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Appendix

Clinical Protocol

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Linnaeus University Sweden

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