refractive error and its management.pptx
- 2. • Slide 2: Introduction to Refractive Errors • What Are Refractive Errors? • Definition: Refractive errors occur when the shape of the eye prevents light from focusing directly on the retina, resulting in blurred vision. • Prevalence: – Affects almost 30% of the global population. – Myopia (nearsightedness) is particularly common in East Asia, while hyperopia and astigmatism are prevalent in other regions. • Significance: – Refractive errors are the leading cause of visual impairment worldwide, but most can be easily corrected with glasses, contact lenses, or surgery. – Untreated refractive errors can lead to reduced quality of life and can contribute to secondary complications (e.g., amblyopia in children)
- 3. • Slide 3: Types of Refractive Errors • 1. Myopia (Nearsightedness) • Description: – Light is focused in front of the retina, causing distant objects to appear blurry. • Cause: – The eye is too long, or the cornea is too curved. • Symptoms: – Difficulty seeing objects at a distance (e.g., road signs, classroom blackboards). – Eye strain, especially after prolonged near work. • 2. Hyperopia (Farsightedness) • Description: – Light is focused behind the retina, causing nearby objects to appear blurry. • Cause: – The eye is too short, or the cornea is too flat. • Symptoms: – Difficulty seeing close objects clearly (e.g., reading, using a phone). – Eye fatigue or headache after reading or doing near work. • 3. Astigmatism • Description: – The cornea or lens has an irregular shape, causing light to focus at multiple points on the retina, leading to blurred vision at all distances. • Cause: – Uneven curvature of the cornea or lens, which distorts vision. • Symptoms: – Blurred or distorted vision. – Eye strain and headaches, especially after long periods of visual focus. • 4. Presbyopia • Description: – A condition related to age-related loss of accommodation, making it difficult to focus on nearby objects. • Cause: – Stiffening of the crystalline lens of the eye, usually after the age of 40. • Symptoms: – Difficulty reading small print. – Need to hold reading materials farther away.
- 4. • . • Slide 4: Pathophysiology of Refractive Errors • 1. Myopia (Nearsightedness) • Mechanism: – The light entering the eye focuses in front of the retina. – Cause: • Eye is too long from front to back (axial myopia). • Cornea or lens has excessive curvature (refractive myopia). • 2. Hyperopia (Farsightedness) • Mechanism: – The light entering the eye focuses behind the retina. – Cause: • Eye is too short (axial hyperopia). • Cornea or lens has insufficient curvature (refractive hyperopia). • 3. Astigmatism • Mechanism: – Light is focused at multiple points on the retina due to an irregularly shaped cornea or lens. – The eye's optical system does not focus light uniformly, leading to blurred vision. – Cause: • The cornea or lens is not spherical, but more like the shape of a football, causing uneven focus. • 4. Presbyopia • Mechanism: – Loss of the eye's ability to focus on nearby objects due to the stiffening of the lens. – Cause: • The natural lens becomes less flexible with age, reducing its ability to change shape and focus on close objects.
- 5. • Slide 5: Symptoms of Refractive Errors • Common Symptoms Across All Refractive Errors: • Blurred Vision: – A hallmark symptom. The degree and nature of the blur depend on the type of refractive error (near vs. distant vision). • Eye Strain: – Caused by the constant effort to focus on objects, especially during tasks like reading or using digital screens. • Headaches: – A frequent symptom, particularly in cases of uncorrected or high refractive errors. Straining to focus can lead to tension headaches. • Squinting: – Often seen in myopia, as squinting can momentarily improve focus by narrowing the eyelids, which reduces the amount of light entering the eye. • Difficulty with Night Vision: – Common in myopia, astigmatism, or when there’s a high refractive error. The distortion of light at night can cause glare and halos. • Double Vision (Diplopia): – More common in astigmatism, as blurred or distorted light is focused at multiple points, leading to double vision or ghost images. • Specific Symptoms by Refractive Error: • Myopia: – Blurry vision at a distance. – Difficulty seeing road signs, movie screens, or whiteboards at school. • Hyperopia: – Blurry vision up close. – Difficulty reading, especially for prolonged periods. • Astigmatism: – Blurred or distorted vision at all distances. – Visual distortions such as "wavy" lines. • Presbyopia: – Difficulty reading fine print, especially in low-light conditions. – Holding books, phones, or menus farther away to see clearly