How does diabetes affect refractive error?

Diabetes mellitus affects the eye, with the most commonly reported long-term changes being cataract and diabetic retinopathy. Acute hyperglycemia is associated with myopic refraction, but refraction becomes less myopic (or even hyperopic) with lowering of the levels of glycemia.

What is Hypermetropic shift?

Hyperopic shifts (left side images) can occur if the lens is positioned too posteriorly or if there is a decrease in the refractive index of the lens. Myopic shifts (right side images) can occur if the lens is positioned too anteriorly or if there is an increase in the refractive index of the lens.

Can diabetes cause refractive error?

Diabetes mellitus is a complex metabolic disorder that involves the small blood vessels, often causing widespread damage to tissues, including the eyes’ optic refractive error. In patients with newly diagnosed diabetes mellitus who have unstable blood glucose levels, refraction may be incorrect.

What is transient refractive changes?

Transient refractive changes have been reported during periods of hyperglycemia, or falling blood glucose level during intensive glycemic control . Myopia has been reported to develop in hyperglycemia and that following therapy, there is a hyperopic shift .

Why does diabetes cause a myopic shift?

Duke-Elder suggested that hyperglycemia causes myopic shift, while a decrease in blood glucose levels leads to hyperopic shift due to the osmotic force between the crystalline lens and the aqueous humor that results from changes in molecular concentration.

Why does lens swell with hyperglycemia?

Excess glucose in the lens is converted to sorbitol during hyperglycemia. Sorbitol is poorly permeable and accumulates in the lens. When blood glucose reduces, the difference in osmotic pressure results in the influx of water from the aqueous humour into the lens, causing lenticular swelling[3],[6],[7].

What is myopic shift?

A myopic shift is an increase in the degree of nearsightedness. This can be due to natural aging of the eye, but it can also be the result of cataracts or diabetes. For cataracts, this can be when the protein clumps form over the nucleus of the lens, causing the greatest opacity. The treatment is usually surgery.

What causes hyperopic shift?

In the posterior segment, hyperopic shift is caused because the retina is moving forward, usually from subretinal fluid; and for neuro-op, that’s steroids causing central serous retinopathy. But anything that causes a serous detachment can do this.

What is PSC eye?

Posterior Subcapsular cataract is a type of cataract, where in, there is opacification in the posterior or back portion of the crystalline lens. This type of cataract can occur alone or in combination with other types of cataracts as well.

What is a 2+ cataract?

These cataracts can be graded on a scale of trace to 4+, with trace being barely any visible opacification. Grade 1+ is when <5% of the posterior capsule is obscured, and Grade 2+ is when approximately 30% of the capsule is obscured.