Human Eye & Vision Support Systems
📚 Topic Overview: Human Eye & Vision Support Systems
This topic explains how sunlight splits into colours, how the human eye works, how to care for vision, and the systems that support individuals with limited or no eyesight. Concepts include dispersion, eye structure, hygiene, Braille reading, and learning aids.
1. Sunlight – Dispersion
Concept / Theory
Dispersion is the splitting of white light into seven colours when it passes through a prism. These colours form the VIBGYOR spectrum. Each colour bends differently because each has a different wavelength.
Analogy / Examples
- Seeing a rainbow after rainfall is natural dispersion.
- వర్షం తరువాత ఆకాశంలో కనిపించే ఇంద్రధనస్సు కాంతి వ్యాపన ఫలితం.
Conversions / Formulas
- No numerical formulas are required, but remember colour order: VIBGYOR.
| English | Telugu |
|---|---|
| Dispersion | వ్యాపనం |
| Spectrum | రంగుల వరుస |
| Prism | ప్రిజమ్ |
A glass chandelier scatters sunlight into small rainbows on the floor. This happens due to dispersion through shaped glass pieces.
Always remember violet bends the most; red bends the least. This helps eliminate wrong options.
2. Human Eye
Concept / Theory
The human eye works like a natural optical device. Light enters through the cornea, passes through the pupil, is focused by the lens, and forms an image on the retina. The retina converts this image into electrical signals sent to the brain through the optic nerve.
Analogy / Examples
- The eye lens works like a camera lens focusing light on the film/sensor.
- కంటి లెన్స్, కెమెరా లెన్స్ లాగానే కాంతిని కేంద్రీకరిస్తుంది.
Conversions / Formulas
- Nature of Image on Retina → Real, inverted, smaller.
| English | Telugu |
|---|---|
| Cornea | కార్నియా |
| Retina | రెటీనా |
| Optic Nerve | ఆప్టిక్ నర్వ్ |
When a student shifts focus quickly from a book to the blackboard, the eye lens changes its curvature—a process called accommodation.
Identify eye parts and their correct functions. Matching-type questions commonly appear.
3. Care of the Eyes
Concept / Theory
Proper eye care helps prevent strain and infection. Good lighting, regular blinking, maintaining distance from screens, and eating vitamin A–rich foods support healthy vision.
Analogy / Examples
- Dry eyes from excessive screen time improve when blinking consciously.
- ఎక్కువసేపు మొబైల్ ఉపయోగిస్తే కళ్లెండిపోవటం సాధారణం.
Conversions / Formulas
- Minimum reading distance: 25 cm.
| English | Telugu |
|---|---|
| Hygiene | శుభ్రత |
| Vitamin A | విటమిన్ A |
| Eye strain | కంటి అలసట |
Children reading in dim light often face headaches because the eye muscles work harder to focus.
Remember foods rich in Vitamin A: carrots, milk, leafy vegetables. These appear frequently in questions.
4. Braille System
Concept / Theory
Braille is a tactile writing system for individuals with visual challenges. It uses raised dots arranged in six-dot cells. Each pattern represents letters, numbers, or symbols.
Analogy / Examples
- Reading Braille is like identifying patterns through touch.
- బ్రెయిల్ లిపి స్పర్శ ద్వారా చదవబడుతుంది.
Conversions / Formulas
- Basic Braille cell = 6 dots (2 × 3 arrangement).
| English | Telugu |
|---|---|
| Braille | బ్రెయిల్ |
| Tactile | స్పర్శ ఆధారిత |
| Dots | చుక్కలు |
ATMs, hotel room numbers, and lift buttons often include Braille labels to guide visually challenged persons.
Remember “six-dot system” — most direct questions relate to this.
5. Visually Impaired Persons
Concept / Theory
Individuals with partial or total loss of eyesight use assistive devices such as white canes, guide dogs, tactile books, audio materials, and Braille. Early support improves learning and independence.
Analogy / Examples
- A talking calculator helps a student with low vision do maths independently.
- చూపు సమస్య ఉన్నవారు ఆడియో పుస్తకాలు వినడంవల్ల చదువుకోవచ్చు.
Conversions / Formulas
- No formulas; focus is on support systems and tools.
| English | Telugu |
|---|---|
| Low vision | తక్కువ చూపు |
| Assistive devices | సహాయక పరికరాలు |
| White cane | తెల్ల కర్ర |
A school library may include tactile diagrams enabling visually impaired children to feel shapes and figures.
Questions often ask which tools help students with low vision: white cane, Braille books, audio tools, tactile maps.