Presbyopia: overview, symptoms, cause, diagnosis and management

Presbyopia is an age-related disease that weakens one’s ability to see nearby objects clearly. As camera need to focus the object to click clear pictures similarly our eyes have a good ability to focus the light rays coming from the objects. More amount of power is required to focus near objects. As the age increases, this ability starts to fade gradually. The word presbyopia comes from a Greek word which means ‘old eye’. You can feel it when you have an urge to hold a newspaper or a book at a distance of an arm length to read text clearly. It is easy to diagnose and can be managed by spectacles or surgery.

Most people start experiencing the effects of presbyopia after the age of 40 and it gradually worsens over time. There was around 1.8 billion people with presbyopia worldwide in 2015. The most common cause of visual impairment in United States is presbyopia.

Symptoms

The symptoms of presbyopia are

• Blurred vision while looking at nearby objects or smartphones
• Eye strain while reading books or reading nearby text
• Need to keep things farther to focus on them properly but the they get smaller in size.
• Headaches
• Visual fatigue

The symptoms are similar to farsightedness but they are different diseases. It is common to have presbyopia along with other refractive diseases. An individual may also have different types of refractive error in different eyes.

Causes

We are able to see an object because the reflected light from an object is bent by our eyes to form an image on the retina. This bending or focusing ability of eyes depends upon the cornea and lens. Cornea is outer curvy transparent part of the eye which has the highest and constant power to bend the light rays. The finer adjustment to it is done by the lens which is situated behind the colored iris. Lens is able to do it because its thickness is variable which is controlled by the help of muscles. This variability provides us the power of accommodation and we are able to see objects kept at anywhere clearly. To see the near objects clearly the lens thickens with the help of surrounding muscles. However, the lens stiffens and becomes less elastic as the age increases and it is unable to change its shape upon the action of muscles while looking at nearby objects. Aging also affects the muscle fibers around the lens by making it harder. So, presbyopia is a symptom highlighting that the body is becoming old.

Diagnosis

Presbyopia is an easy to diagnose the condition. The doctors which deal with the problems of eyes are known as ophthalmologists. The specialist will conduct ophthalmic examination which will include refraction testing and a general eye health checkup. Refraction testing is used to check whether the person is suffering from myopia, hypermetropia, astigmatism or presbyopia. Refraction testing involves reading different type of text kept at a near and far distance from the eye.

Management

The aging is an irreversible process and so does presbyopia. It can’t be cured but can be managed easily. The goal of management is to make the individual see near things clearly. Management options include wearing glasses or contact lenses or in some cases surgery.

Eye glasses: It is an easy, safe and simple measure to correct the vision problems. People who are suffering from presbyopia whose eyes are otherwise normal that is free from any other refractive disorders can use reading glasses.

• Reading glasses: These are convex glasses having a power in positive diopters. You can buy them without prescription. You should start with the lowest power and check whether the glasses relieve your symptoms or not. They need to be removed after finishing the near work

You may need to consult an ophthalmologist if non-prescription glasses are not suitable for you. Your doctor can provide exact power deficit after an eye examination. If you are suffering from other refractive error such as farsightedness or nearsightedness or astigmatism you need prescription glasses and you need a proper ophthalmologic consultation. Prescription glasses can include

• Bifocals: these glasses have lower portion which is convex and the upper portion for your distance prescription.
• Trifocals: these glasses have three distinct visible area for close view, mid-range and for distance vision.
• Progressive glasses: these glasses, unlike bifocals or trifocals, don’t have a sharp demarcation but the power of lens gradually varies from the top to bottom of the glass to provide better quality of image as compared to bifocals or trifocals. These glasses are becoming very popular nowadays.

Contact lenses: these can be used when people don’t want to use eyeglasses but there are some limitations and prerequisite to use contact lenses. There are different kind of contact lenses available like multifocal, monovision etc. In monovision, one eye is corrected for distance vision and the other eye for the near vision. Multifocal contact lenses have different zones of different powers and you are using both far and near vision at the same time. The brain automatically learns to use which vision is better. However, the images are less sharp than the normal.

Surgery: surgical options are available for the management of presbyopia which have its own advantages and disadvantages. These procedures are permanent. Different types of surgical procedure are

• Refractive surgery: refractive eye surgery changes the shape of cornea. The curvature of cornea is made more round so that it can bend light ray more effectively. The near vision will improve. It is done in nondominant eye such that dominant eye can be used to look for far things clearly while the other eye can see near things clearly. The is the same as using monovision contact lenses but the method is permanent. There are various kind of refractive surgery available nowadays like LASIK, LASEK or photorefractive keratectomy for this procedure.
• Lens implants: the stiffened lens in the eye is replaced by a synthetic lens. Several types of lens implants are available nowadays. Some are only for near vision while some changes shape to allow to visualize thing both at far and near. Lens implant alters the quality of the image.

You may still need glasses after surgical procedure. Before opting for any treatment, you should properly discuss the advantages and disadvantages of each procedure.

References

• Fricke TR, Tahhan N, Resnikoff S, et al. Global Prevalence of Presbyopia and Vision Impairment from Uncorrected Presbyopia: Systematic Review, Meta-analysis, and Modelling. Ophthalmology 2018; 125:1492.
• Rosenbloom AA Jr. New aged and old aged: impact of the Baby Boomer. Optometry 2003; 74:211.
• https://nei.nih.gov/health/errors/presbyopia
• https://www.aao.org/eye-health/diseases/presbyopia-treatment
• https://www.aao.org/eye-health/diseases/what-is-presbyopia