Definition and Overview

Cataracts are one of the most common vision-related complications of uncontrolled diabetes along with glaucoma and retinopathy. A cataract is the clouding of the eye’s lens. Diabetes, on the other hand, is a life-long disease that compromises the body’s ability to produce or effectively respond to the hormone insulin, resulting in high levels of glucose (sugar) in the blood.

A person with uncontrolled diabetes has an increased risk of cataract because high levels of blood glucose can cause the eye lens to swell. Diabetes can also cause a substance called sorbitol to collect in the eye, which can also make the lens less clear and more opaque.

Although people with diabetes have an increased risk of developing vision-related problems, they can avoid or prevent cataract from occurring. They can do this by working closely with an endocrinologist (a doctor specialising in diagnosing and treating diseases and disorders of the endocrine system including diabetes mellitus) to control their blood glucose levels and undergoing regular eye check with an ophthalmologist.

If diabetes is not properly controlled and the cataract is left untreated, it can lead to the continual loss of vision and total blindness.

Causes of Condition

Diabetes is a term that refers to a group of metabolic diseases characterised by high levels of blood glucose. The disease has two main types, which are classified based on what is causing them.

  • Type 1 diabetes is an autoimmune disorder that occurs when the body’s immune system attacks the pancreas beta cells that produce insulin, a hormone that enables the body to efficiently use and store sugar. Without the beta cells, glucose cannot be moved out from the bloodstream and into the body’s cells.

  • Type 2 diabetes occurs due to the combination of genetics and lifestyle factors that cause insulin resistance. Unlike type 1 diabetes, type 2 diabetes can be prevented through a healthy lifestyle.

There is no cure for both types. Available treatment focuses on normalising or stabilising a person’s blood glucose level and controlling symptoms.

Diabetes can lead to cataract formation due to abnormally high levels of sugar in the eye.

The eye lens obtains the nutrients it needs from aqueous humour, the fluid that fills the front portion of the eye. This fluid carries glucose and oxygen, which are two of the eye cell’s energy sources. When sugar levels in the eye increase due to diabetes, the lens swells and becomes clouded. When left untreated, this can lead to the formation of cataracts.

Key Symptoms

The main signs and symptoms of cataracts are:

  • Blurred, cloudy or misty vision

  • Difficulty driving at night

  • Fading or yellowing of colours

  • Frequent changes to eye glass or contact lens prescription

  • Seeing halos around lights

  • Sensitivity to light and glare

  • Spots in vision

Some patients also complain of eye pain as well as sudden vision changes and headaches.

Who to See and Types of Treatments Available

People diagnosed with diabetes must work closely with their endocrinologist to control their symptoms and prevent complications from occurring. As part of their treatment, they are advised to undergo regular eye exams with an ophthalmologist to help diagnose cataract and other vision problems related to diabetes in their early stages.

In some cases, the symptoms of early cataract can be improved by using anti-glare sunglasses, magnifying lenses, and brighter lighting. However, if these measures do not help, the only option left is cataract surgery in which the clouded lenses are removed and replaced with artificial ones.

Cataract surgery is an outpatient procedure performed under local anaesthetic. It is relatively straightforward and lasts about an hour. Following pre-surgical preparations, the ophthalmic surgeon will proceed by removing the damaged, clouded lens. The most common techniques in use today are:

  • Phacoemulsification - When compared to conventional cataract surgery that involves the use of a handheld blade, phacoemulsification is safer and more effective. It uses a high-frequency ultrasound device to break up the damaged lens and suction to remove the fragmented pieces.

  • Extracapsular cataract surgery - This technique is recommended if the lens has become too dense that it can no longer be removed through phacoemulsification. It involves making a larger incision so the cataract can be removed in one piece.

  • Laser cataract surgery - Femtosecond lasers are now also being used in creating a corneal incision so the damaged lens can be easily removed. This method uses light energy that minimises damage to nearby tissues.

The removed damaged lens is then replaced with an intraocular lens (IOL). In the past, all patients who undergo cataract surgery receive the standard lens. However, as lens technology improves, there is now a wide range of lenses designed to address common refractive errors such as near- and farsightedness.

  • Monofocal lens - This is the standard lens commonly used in cataract surgery. It delivers excellent vision but only at one distance. Depending on the patient’s preference, the focal point can be set to near, intermediate, or far.

  • Multifocal lens - Provides clear vision at several distances.

  • Toric lens - Just like a monofocal lens, this lens delivers excellent vision at a single distance. It is also used for the treatment of astigmatism.

  • Accommodating lens - A lens that has the ability to shift position so the focus can be adjusted at varying distances.

  • Aspheric lens - Improves visual clarity and contrast sensitivity.

Cataract surgery is one of the safest, most performed eye operations with a high success rate. Complications, which are listed below, are very rare:

  • Bleeding

  • Infection (endophthalmitis)

  • Changes in eye pressure

  • Persistent inflammation

  • Swelling of the retina

  • Retinal detachment


  • Diabetic Cataract-Pathogenesis, Epidemiology and Treatment, Andreas Pollreisz and Ursula Schmidt-Erfurth, Department of Ophthalmology and Optometry, Medical University Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria

  • Emmett T. Cunningham; Paul Riordan-Eva. Vaughan & Asbury’s general ophthalmology. (18th ed.). McGraw-Hill Medical. ISBN 978-0071634205.

  • Hejtmancik; Smaoui (2003), “Molecular Genetics of Cataract”, Genetics in Ophthalmology, Karger Medical and Scientific Publishers, p. 77, ISBN 9783805575782

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