2. Introduction to Refractive Errors
• • Refractive errors occur when light does not
focus properly on the retina
• • Causes include irregular shape of the cornea
or lens
• • Common types: Myopia, Hypermetropia,
Astigmatism, and Presbyopia
3. Myopia (Nearsightedness)
• • Light focuses in front of the retina instead of
on it
• • Distant objects appear blurry
• • Causes: Elongated eyeball, steep corneal
curvature
• • Symptoms: Blurry distance vision, eye strain,
squinting
• • Correction: Concave (minus) lenses, contact
lenses, LASIK surgery
4. Hypermetropia (Farsightedness)
• • Light focuses behind the retina instead of on
it
• • Near objects appear blurry, but distant
vision is clear
• • Causes: Short eyeball, flat corneal curvature
• • Symptoms: Eye strain, headaches, difficulty
in reading
• • Correction: Convex (plus) lenses, contact
lenses, LASIK surgery
5. Astigmatism
• • Uneven curvature of the cornea or lens
causes light to focus unevenly
• • Results in blurred vision at all distances
• • Symptoms: Blurred or distorted vision, eye
strain, headaches
• • Correction: Cylindrical lenses, toric contact
lenses, refractive surgery
6. Presbyopia (Age-related
Farsightedness)
• • Loss of lens elasticity with age, making near
vision difficult
• • Typically occurs after 40 years of age
• • Symptoms: Difficulty reading, need for
brighter lighting, eye fatigue
• • Correction: Bifocal or progressive lenses,
reading glasses, multifocal contact lenses
7. Diagnosis of Refractive Errors
• • Visual acuity test (Snellen chart)
• • Retinoscopy (objective refraction test)
• • Autorefraction (computerized refraction
assessment)
• • Subjective refraction (patient-driven test
with trial lenses)
8. Management and Treatment
• • Spectacle lenses (glasses) - simplest
correction method
• • Contact lenses - provide wider field of view
• • Refractive surgeries (LASIK, PRK, SMILE) -
permanent correction
• • Orthokeratology - temporary reshaping of
cornea using special lenses
9. Conclusion
• • Refractive errors are common and affect
vision clarity
• • Early diagnosis and appropriate correction
are essential
• • Regular eye check-ups help in timely
detection and treatment
• • Various correction options available
including glasses, contacts, and surgery
