Type 2 Diabetes and Cataracts Formation


Diabetes significantly raises the risk of developing cataracts.

Cataracts, often called "cloudy lenses," obscure vision over time.

Proper diabetes management is crucial to mitigate cataract formation.

What is a Cataract?


A cataract is a prevalent ocular condition that affects the clarity of vision, typically occurring as a natural part of the aging process.

The term "cataract" originates from the Greek word "kataraktes," which means "waterfall" or "downrush."

This term was likely used metaphorically to describe the cloudy, opaque appearance that a person's eye might take on as the condition progresses.

In essence, a cataract refers to the clouding of the eye's natural lens, which is situated behind the iris, the colored part of the eye.

The lens plays a critical role in focusing light onto the retina, the light-sensitive tissue lining the back of the eye.

This focused light forms visual images that are then transmitted to the brain through the optic nerve.

As a cataract develops, the normally transparent lens becomes progressively opaque due to changes in the lens proteins and the buildup of cellular debris.

This opacity interferes with the passage of light through the lens, causing visual impairment. Individuals with cataracts often report symptoms such as blurred or hazy vision, increased sensitivity to glare, difficulty seeing at night, and a fading of vibrant colors.

Some Patho-physiological changes in Cataract

The pathophysiology of cataracts involves a complex interplay of biochemical, structural, and cellular changes within the lens of the eye.

Cataracts develop when the balance between lens proteins, antioxidants, and other factors essential for maintaining lens transparency is disrupted.

Several underlying mechanisms contribute to the formation and progression of cataracts:

1. Protein Aggregation and Denaturation: The lens of the eye is primarily composed of water and proteins called crystallins.

These proteins are critical for maintaining lens clarity and refractive properties. With age, exposure to environmental factors like ultraviolet (UV) radiation, and oxidative stress, crystallins can undergo conformational changes, leading to protein aggregation and denaturation.

This disrupts the orderly arrangement of proteins and contributes to the cloudy appearance of cataracts.

2. Oxidative Stress: Oxidative stress occurs when there is an imbalance between the production of reactive oxygen species (ROS) and the body's ability to neutralize them with antioxidants.

Oxidative stress damages cellular components, including proteins, lipids, and DNA.

In the lens, oxidative stress is particularly damaging due to its limited regenerative capacity.

Accumulated oxidative damage impairs protein function and structural integrity, further contributing to cataract formation.

3. Glycation: Glycation is a process in which sugars bind to proteins without enzyme involvement, forming advanced glycation end products (AGEs).

AGEs accumulate over time, altering the structure and function of lens proteins.

This process can lead to cross-linking of proteins, which contributes to protein aggregation, reduced flexibility, and opacity within the lens.

4. Ion Imbalance and Water Regulation: Maintaining the proper balance of ions and water is crucial for lens transparency.

Changes in ion concentrations, particularly calcium, disrupt cellular homeostasis and contribute to cellular dysfunction.

Altered water regulation affects lens hydration and the maintenance of lens curvature, both of which are necessary for clear vision.

5. Genetic Factors: Certain genetic mutations can predispose individuals to cataract formation.

These mutations may affect the structure of lens proteins, the efficiency of antioxidant defense systems, and other critical pathways involved in maintaining lens transparency.

6. Metabolic Changes: Conditions such as diabetes can lead to metabolic changes that impact lens health.

High blood sugar levels in diabetes promote glycation, oxidative stress, and altered metabolic pathways, accelerating cataract development.

7. Accumulation of Lipids and Calcium: The accumulation of lipids and calcium in the lens can contribute to opacification.

These deposits can disrupt cellular function and hinder light transmission through the lens.

Overall, cataract formation is a multifaceted process involving the interplay of genetic predisposition, environmental factors, oxidative stress, protein modifications, and cellular dysfunction.

While age remains the primary risk factor, understanding the pathophysiology of cataracts helps researchers develop strategies to prevent, delay, or treat their progression.

Promoting antioxidant-rich diets, UV protection, and early intervention through surgical procedures are among the approaches aimed at mitigating the impact of cataracts on vision.

Role of Diabetes in Cataract Development

Diabetes plays a significant role in the development and progression of cataracts, contributing to an increased risk and earlier onset of this ocular condition.

The relationship between diabetes and cataracts is primarily attributed to the metabolic disturbances and oxidative stress associated with diabetes.

Here's how diabetes influences cataract development:

1. Oxidative Stress: Diabetes is characterized by chronic hyperglycemia (high blood sugar levels), which leads to increased production of reactive oxygen species (ROS) in the body.

Elevated glucose levels contribute to oxidative stress, which damages cellular components, including the proteins in the lens.

Oxidative stress disrupts the delicate balance between antioxidants and ROS, accelerating protein denaturation, aggregation, and opacification in the lens.

2. Advanced Glycation End Products (AGEs): In diabetes, excess glucose can react with proteins in a process known as glycation, forming AGEs.

These AGEs accumulate in various tissues, including the lens.

They alter the structure and function of lens proteins, leading to protein cross-linking, aggregation, and opacity, all of which contribute to cataract formation.

3. Aldose Reductase Pathway: Elevated glucose levels in diabetes activate the aldose reductase pathway.

This pathway converts excess glucose into sorbitol, which can accumulate in the lens cells, leading to osmotic stress and water influx.

This process contributes to lens swelling and damage to lens fibers, contributing to cataract development.

4. Decreased Antioxidant Defense: Diabetes can reduce the body's natural antioxidant defense mechanisms.

As a result, the lens becomes more susceptible to oxidative damage, which plays a pivotal role in cataract initiation and progression.

5. Inflammatory Pathways: Chronic inflammation is another hallmark of diabetes.

Inflammatory molecules can promote lens cell damage and alter the balance between degradation and repair processes in the lens, ultimately contributing to cataract formation.

6. Increased Sorbitol Levels: The accumulation of sorbitol due to the aldose reductase pathway in diabetes can lead to imbalances in osmotic pressure, altering lens hydration and causing lens opacification.

7. Lens Vascular Changes: Diabetes can cause microvascular changes in the lens, affecting its nutrient supply.

These changes can impair the lens's ability to maintain transparency and repair damage.

8. Accelerated Aging: Diabetes is associated with accelerated aging processes throughout the body.

In the lens, this can manifest as increased protein cross-linking and decreased protein turnover, contributing to the accumulation of damaged proteins and the formation of cataracts.

It's important to note that the impact of diabetes on cataracts is influenced by various factors, including the duration and severity of diabetes, glycemic control, and individual susceptibility.

Proper management of diabetes, including maintaining stable blood sugar levels, adopting a healthy lifestyle, and managing other associated health conditions, can help mitigate the risk and progression of cataracts.

Regular eye examinations in diabetics are also crucial for early detection and timely intervention.

Symptoms of Cataract in Diabetics

Cataracts can manifest with similar symptoms in both diabetics and non-diabetics, but individuals with diabetes may experience these symptoms earlier and with greater severity due to the underlying metabolic changes associated with the condition.

Here are the common symptoms of cataracts, particularly in diabetics:

1. Blurred or Cloudy Vision: One of the earliest signs of cataracts is a gradual decline in the clarity of vision.

Blurriness or cloudiness can make it difficult to see details and perform daily activities such as reading or recognizing faces.

2. Increased Sensitivity to Glare: Individuals with diabetic cataracts often report heightened sensitivity to glare, particularly from bright lights or sunlight.

Glare can cause discomfort and make it challenging to see in well-lit environments.

3. Difficulty Seeing in Low Light: Diabetic cataracts can lead to reduced vision in dim or low-light conditions.

Night driving or navigating in poorly lit areas can become more challenging due to decreased contrast sensitivity and impaired ability to adjust to changes in lighting.

4. Frequent Changes in Eyeglass Prescription: As cataracts progress, the changing clarity of the lens can result in frequent changes in the prescription for eyeglasses or contact lenses.

However, even with prescription updates, vision may not be adequately restored.

5. Halos Around Lights: Many individuals with cataracts, including diabetics, experience the appearance of halos or rings around lights, especially at night.

This phenomenon can contribute to difficulties with night vision and driving.

6. Diminished Color Perception: Cataracts can cause colors to appear less vibrant or faded.

This can affect an individual's ability to distinguish between different hues and shades.

7. Double Vision: Cataracts can lead to double vision (diplopia) in one eye, which may resolve when the affected eye is closed.

Double vision occurs when light entering the eye is split into two separate images due to the clouded lens.

8. Frequent Changes in Reading Glasses: If you wear reading glasses, you may notice that they become less effective as cataracts develop.

The progressive blurring of vision can make it challenging to read or perform close-up tasks.

9. Decreased Depth Perception: With cataracts, depth perception can be compromised, making it difficult to judge distances accurately.

This can impact activities that require precise spatial awareness, such as climbing stairs or reaching for objects.

It's important to note that cataracts can develop gradually, and the severity of symptoms can vary from person to person.

People with diabetes should be particularly vigilant about monitoring their eye health and reporting any changes in vision to their healthcare provider.

Regular eye examinations are essential for early detection and timely management of cataracts. 

Diagnosis of Cataract in type 2 Diabetics

The diagnosis of cataract in individuals with type 2 diabetes follows similar procedures to those without diabetes.

However, due to the increased risk and potential for earlier onset of cataracts in diabetics, regular eye examinations are crucial to detect and monitor the condition.

Here's how cataracts are diagnosed in people with type 2 diabetes:

1. Comprehensive Eye Examination: A thorough eye examination is the foundation of cataract diagnosis.

An eye doctor, usually an ophthalmologist or optometrist, will conduct a comprehensive assessment of your eye health, including an evaluation of your visual acuity, eye pressure (intraocular pressure), and examination of the structures at the front and back of your eye.

2. Visual Acuity Test: This test involves reading letters on an eye chart to assess how well you can see at various distances.

A decrease in visual acuity, especially if not correctable with eyeglasses or contact lenses, can indicate the presence of cataracts.

3. Slit Lamp Examination: A slit lamp is a specialized microscope that allows the doctor to examine the front structures of the eye in detail.

This examination helps visualize the lens and its clarity. A cataract is evident as an opaque or cloudy area within the lens.

4. Dilated Eye Exam: In this procedure, the doctor uses eye drops to dilate (enlarge) the pupil, allowing for a more thorough examination of the lens and the back of the eye.

This provides a clearer view of the cataract's location, size, and impact on the retina.

5. Glow or Retroillumination Test: This test involves shining a light through the pupil and assessing the glow or reflection from the cataract.

The appearance of a visible glow indicates the presence of a cataract.

6. Contrast Sensitivity Test: This test assesses the ability to distinguish between objects of varying shades and contrasts.

Cataracts can lead to reduced contrast sensitivity, making it difficult to discern details in certain lighting conditions.

7. Visual Field Test: A visual field test measures your peripheral (side) vision.

Cataracts can cause visual field abnormalities by blocking or distorting light as it enters the eye.

This test helps evaluate the extent of visual impairment caused by cataracts.

8. Discussion of Symptoms and Medical History: If you have type 2 diabetes, discussing your symptoms and medical history with your eye doctor is essential.

Diabetic cataracts may progress more rapidly, and symptoms might be more pronounced.

Informing your doctor about your diabetes and any related complications can help guide the diagnostic process.

Routine eye exams for individuals with type 2 diabetes should be scheduled according to your healthcare provider's recommendations.

Early detection of cataracts allows for timely intervention and management.

Cataract Treatment in Diabetics

The treatment of cataracts in diabetics is similar to the treatment for cataracts in individuals without diabetes, but there are some important considerations due to the presence of diabetes.

A. Monitoring Blood Sugar Levels: The first step in managing cataracts in diabetics is to ensure that their blood sugar levels are well controlled.

High blood sugar levels can accelerate the progression of cataracts.

Therefore, it is essential for diabetics to work with their healthcare team to manage their diabetes effectively.

B. Regular Eye Exams: Diabetics should have regular eye examinations, at least annually or as recommended by their eye care professional.

These exams can help detect cataracts at an early stage and monitor their progression.

C. Glasses and Contact Lenses: In the early stages of cataracts, updating prescription glasses or contact lenses may improve vision and alleviate some of the symptoms associated with cataracts, such as blurry vision and glare.

D. Surgical Treatment (Cataract Surgery): When cataracts significantly affect a person's vision and quality of life, surgical intervention is usually necessary.

E. Management of Diabetic Retinopathy: Diabetics with cataracts may also have diabetic retinopathy, which is a condition affecting the blood vessels in the retina.

It's crucial to manage both conditions concurrently. Diabetic retinopathy may require laser therapy, injections, or other treatments as recommended by an ophthalmologist.

It's essential for individuals with diabetes to work closely with their healthcare team, including an eye specialist, to manage both their diabetes and any associated eye conditions like cataracts. Early detection and proper management are key to preserving vision and preventing complications.

Cataract surgery in Diabetics

Cataract surgery is highly effective and involves removing the cloudy lens and replacing it with an artificial intraocular lens (IOL).

This procedure is generally safe and can be performed on diabetics, but there are some considerations:

I. Preoperative Evaluation: Diabetics may require a more thorough preoperative evaluation to assess their overall health and ensure their diabetes is well-controlled before surgery.

II. Blood Sugar Control: It's important to maintain good blood sugar control both before and after surgery to minimize the risk of complications.

III. Cataract Surgery Technique: Some surgeons may prefer specific surgical techniques, such as phacoemulsification, for diabetics to minimize inflammation and promote faster healing.

IV. Postoperative Care: Diabetics may need careful monitoring after cataract surgery to ensure that their blood sugar levels remain stable, and any diabetic retinopathy is managed appropriately.

Take Home Notes!

To sum it up, I want to give a study example of type 2 diabetics, among whom, there were patients taking statins. In both groups, statin users and nonusers, the scientists found out an increased risk of developing cataract.

At the end of the day, voice was raised in suggesting the monitoring of crystalline lenses in type 2 diabetics, especially those on statin treatment.

So, as you may see, do not be astonished with news like this. When a chronic disease like diabetes, is part of your life, be prepared of many bad consequences especially when uncontrolled.

I do not want to scary you, but to make you realize the importance of being healthy. If cataract could be as a consequence of an accidental injury or trauma or age; then, this could be considered as your fate.

This is true even in cases when you have family history of cataracts or undergoing radiation treatment or working exposed to sunlight.

However, it is a pity to hear that you were not strong enough to say a big “NO” to alcohol, smoking, or eating foods in excessiveness.

In other words, eating healthy, implementing good behavioral habits, trying to be way from “risky” factors can reduce your chances of developing cataracts and having other health problems.

This will also help improve your glucose metabolism and your diabetes control too.

I do not want to repeat the same words, but all of us need “Determination, Determination, and Determination”. Electronic communication tools are helping each of us in spreading the news.

Keep in touch with latest news and continue your battle against type 2 diabetes with “Determination”.

All the best!

Written by Dr.Albana Greca Sejdini, Md, MMedSc       

Medically reviewed by Dr.Ruden Cakoni, MD, Endocrinologist

Last reviewed 09/13/2023

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