Cataracts : First signs, symptoms, causes, and diagnosis

What does a cataract look like?

The lens in the eye is mostly made of water and protein. The protein is arranged in a way that keeps the lens clear and lets light pass through it. But as we age, some of the protein may clump together and start to cloud a small area of the lens. This is a cataract. Over time, the cataract may cloud more of the lens, making it harder to see. Cataracts can develop in one or both eyes. If they develop in both eyes, one will be more affected than the other. When looked at from the outside, a person with a cataract may appear to have a film over their eye. This can be misleading, as the cataract is actually in the lens inside the eye. A person with a cataract may not be able to see well enough to carry out normal daily activities, such as reading or watching television, or recognize people’s faces. This is because the cloudy lens is like having mist over a window or dirt on a camera lens. When someone is diagnosed with a cataract, it is usually nothing to worry about. It is very rare for cataracts to cause total blindness. However, it is important to be aware that clear lens extraction is not usually available on the NHS. This form of refractive lens exchange is more commonly used in people having private treatment for refractive errors such as long or short-sightedness. The symptoms of a cataract in the early stages may be improved with new glasses, brighter lighting, anti-glare sunglasses, or magnifying lenses. If these measures do not help, and vision loss is interfering with your everyday activities, then surgery can be considered. Surgery involves removing the cloudy lens and replacing it with an artificial lens. A cataract develops when changes in the natural lens of the eye cause it to become less transparent. The lens is situated inside the eye, just behind the pupil. The lens helps to focus light that passes into the eye, producing clear, sharp images on the retina – the light-sensitive membrane that is located at the back of the eye. However, as it becomes less transparent, it obstructs light as it passes into the eye. This can cause blurry or misty vision. Cataracts are common in older people. It is estimated that around a third of people aged over 65 in the UK have cataracts in one or both eyes. The exact cause of cataracts is currently unknown, but most cases are related to aging. Some researchers have suggested that the protein fibers in the lens become damaged over time, and this may contribute to the formation of cataracts. In younger people, cataracts can be related to an injury, certain medications, or medical conditions such as diabetes.

What are the first signs of cataracts?

Common signs of cataracts include clouded, blurred or dim vision, increasing difficulty with vision at night, sensitivity to light and glare, seeing « halos » around lights, frequent changes in eyeglass or contact lens prescription, fading or yellowing of colors, and double vision in a single eye. These signs may also indicate other eye conditions. Therefore, it is important to see an eye care professional for a diagnosis. Furthermore, some people with cataracts may not even realize it is in its initial stages since the cataract may be small and the early symptoms of cataracts may not interrupt or affect their everyday lives. For example, those who have small cataracts that are not near the visual axis – the path light takes to reach the retina at the back of the eye – may not notice the condition. Recent eye exams should always be done in order for the optometrist or ophthalmologist to detect cataracts and other eye conditions. As cataracts progress, the symptoms slowly develop and become more severe. Although cataracts are generally described in a way to suggest that there is only a single cataract, it is actually common to have many little cataracts spread throughout the lens of the eye. This would cause the effects and symptoms of cataracts to vary from differences in sight and how it disrupts or affects different individual daily schedules and lifestyles.

Additional symptoms

Another symptom of cataracts is a harsher glare from the sun or from a bright light. A so-called « after-image » may be left by bright lights, whereby a light can be seen even after the light has been turned off. This may cause difficulties when driving, especially at night when the oncoming headlights can cause discomfort. A reduction in contrast sensitivity may be noticed, causing problems such as the difficulty in reading the newspaper or seeing the curb and steps on a contrasting floor. In everyday tasks, such as pouring a cup of tea or coffee, a reduced ability or lesser time taken to adjust to changing light levels may be observed. This is because the filtering process of the lens is impeded and this will dampen the ability to change focus with the changes in light levels encountered. The visual acuities, both for distance and for near will diminish. One of the most common early symptoms of cataracts is the need to frequently change your spectacle prescription. The rate of development of cataracts can vary amongst individuals. However, as the cataract progresses, the vision deteriorates and more evident symptoms of the cataract will be noticed. Thanks to recent improvements in modern cataract surgery and lens technology, the option for a wide range of spectacle independence or use is achievable for cataract patients.

Risk factors for cataracts

Some people are more likely to get cataracts because of their genetics. If cataracts run in your family, you may be more likely to develop them at a younger age. This family history can be passed down through either the mother’s or the father’s side of the family. In addition, researchers believe that long-term exposure to bright sunlight may increase the risk of developing cataracts. UVB rays from the sun can damage the cells in the lens. On the other hand, UV rays also raise the amount of certain oxidant molecules called free radicals, which result from natural body processes, such as breathing, and from environmental stresses as well. These molecules can cause the proteins in the lens to lose some of their natural transparency and become cloudy.

Types of cataract

When a cataract is diagnosed, the first thing to be considered is the type of cataract that we are dealing with. Every type of this eye disease has its symptoms and causes, and knowing the exact type of the cataract can help to understand the stage of its progression and choose the right method for cataract removal. There are 4 main types, but the classification is not limited only to these 4; with disease development the cataracts can change and it is possible to have mixed forms. One of the most widespread types is age-related cataract. As it can be understood from the name, age-related cataract appears in the elder patients: most of the people over the age of 60 have some sight changes due to age-related cataract. There are 3 forms of age-related cataracts, depending on the part of the lens that is affected. It can be nuclear sclerosis when the center of the lens is getting harder, or cortical type when the cataract begins in the periphery of the lens and slowly progresses to the center, or posterior subcapsular cataract that starts as a small opacity under the capsule and gradually develops into a larger one covering the visual axis. The second type is congenital cataract which means that a person is born with it or it is developed in the very early years of life. This type is rather rare and can be caused by mother’s infection while pregnancy, injuries, metabolic disorders or inheritance. Traumatic cataract is developed after an eye injury and can appear at once or years after the damage. Also cataracts can be caused by different eye diseases such as glaucoma, uveitis, retinitis pigmentosa and others; these forms are called secondary cataracts. Less widespread types are radiation-induced cataract which can develop after an eye exposure to some amount of radiation and drug-induced cataract, especially if a person uses corticosteroids for a long time.

Causes

Injury to the eye can cause cataracts. The damage can take years to lead to cataracts. Other causes of cataracts are genetics, work, drugs, and radiation. Diabetes could also cause cataracts as they are more likely to form in those with diabetes. Smokers are also at a greater risk of cataracts. Prolonged exposure to sunlight and its harmful ultraviolet rays may also increase cataract risk. This is why the use of sunglasses is very important, especially for young children. Although studies have shown that continuous steroid use may be a cause of cataracts, no research has proven this. Younger people may have cataracts because of eye injuries, but most cataracts start with people who are 40 years and older. Alzheimer’s disease, macular degeneration, diabetic retinopathy, and age-related multiple sclerosis are other eye disorders that can cause cataracts. People should be informed on these types of eye disorders so they can take precautions early on. For example, people with diabetes should get their eyes checked once a year because early diagnosis and timely treatment can prevent vision loss. Unlike glaucoma, a disease in which increased eye pressure is the main cause of nerve damage, cataract is not usually associated with the pressure in the eye. Also, it cannot be « spread » from one eye to the other, although many people may have cataract in both eyes. Cataracts develop at different rates in different people. It is impossible to predict how fast cataracts will develop in someone’s eyes. The severity of symptoms may not be related to the severity of the cataract. For example, vision may be only slightly affected but the person is very aware of the cataract. This is a common dilemma for those who have cataracts. They have to decide whether their small amount of vision loss warrants surgery. Cataracts are a very common eye condition as people age. Whether through naturally aging or other conditions that can cause the development of cataracts, such as diabetes, the lens in the eye can become cloudy and hard.

Cataract treatments

There is currently no medicinal treatment for cataracts, and changes in prescription glasses may only slightly improve the visual symptoms caused by cataracts. When symptoms become frustrating and affect everyday activities, surgical treatment is the only option. Cataract surgery is one of the most common operations performed within the National Health Service, and success rates are very high. During the procedure, which these days is often performed under local anaesthetic as an outpatient or day case, the cloudy lens is removed from the eye and replaced with a clear plastic one. However, in some cases, where a person may not be fit for surgery for some reason, such as a frail elderly person with other medical conditions, then the best advice could be to use stronger glasses and make the best use of lighting and any low vision aids. Some US research is beginning to discover the possibility that taking certain vitamins might slow down the development of cataracts. Vitamin C and E are antioxidants and it is known that cataracts are associated with damage from oxygen-related chemicals over time. The antioxidant vitamins are thought to help to mop up this form of chemical damage. This is exciting research in that it might hold out the promise of a potential future treatment for cataracts but, at present, we have no knowledge of the effects of these vitamins and patients should not start taking them on the basis of these results, as they are not yet proven. Also, it is important for eye health that people have a diet with enough green leafy vegetables, fruit, oily fish, and nuts, which have been shown to help protect the eyes against the development of some eye conditions, according to some research, although again more evidence is required to confirm these findings.