Complete Human Eye, Eye Disorders Short Sightedness and Long Sightedness
Overview of the Human Eye
The human eye is a complex sensory organ that captures light and converts it into electrical signals, which the brain interprets as images. It balances focus, aperture control, and photoreceptor activity to provide clear, detailed vision under a wide range of conditions.
Anatomy of the Eye
- Cornea: Transparent front surface that refracts light.
- Aqueous Humor: Fluid between cornea and lens, maintains pressure.
- Iris & Pupil: Colored muscle adjusts aperture (pupil) size.
- Lens: Flexible structure that fine‑tunes focus onto the retina.
- Vitreous Humor: Gel filling the eye chamber behind the lens.
- Retina: Light‑sensitive layer containing rods (low light) and cones (color).
- Optic Nerve: Transmits visual impulses to the brain.
Physiology of Vision
Light enters through the cornea and pupil, then passes through the lens which adjusts shape (accommodation) to focus images onto the retina. Photoreceptors convert photons into electrical signals. These signals travel via the optic nerve to the visual cortex, where they are processed into perception.
Short Sightedness (Myopia)
Myopia occurs when the eyeball is too long or the cornea too curved, causing light to focus in front of the retina. Distant objects appear blurred.
Causes
- Genetic predisposition
- Excessive near‑work or screen time
- Environmental and developmental factors
Symptoms
- Blurry distance vision
- Squinting to see far objects
- Headaches from eye strain
Long Sightedness (Hyperopia)
Hyperopia arises when the eyeball is too short or the lens too flat, causing light to focus behind the retina. Close objects appear blurred, while distant vision may remain clearer.
Causes
- Genetic factors
- Age‑related changes in lens flexibility
- Developmental anomalies
Symptoms
- Difficulty reading or focusing on nearby tasks
- Eye strain and fatigue
- Headaches after close work
Correction Methods
| Disorder | Optical Solution | Other Treatments |
|---|---|---|
| Myopia | Concave (minus) lenses in glasses or contacts | Laser surgery (LASIK), orthokeratology |
| Hyperopia | Convex (plus) lenses in glasses or contacts | Laser surgery, lens implants |
Regular eye exams are essential to update prescriptions and monitor eye health. Lifestyle modifications—such as taking frequent breaks during near work—can help reduce progression in children.
Conclusion
The human eye’s intricate structure enables remarkable visual acuity, but common refractive errors like myopia and hyperopia can impair vision. Understanding their anatomical and physiological basis allows effective correction through lenses or surgical interventions, ensuring clear vision and reducing eye strain.