Refrective error (opthalmology)
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This document discusses refractive errors of the eye, including emmetropia, myopia, and hypermetropia. Emmetropia is the normal optical condition where light focuses on the retina. Myopia, or near-sightedness, occurs when light focuses in front of the retina. Symptoms include indistinct distant vision. Hypermetropia, or far-sightedness, is when light focuses behind the retina, causing blurred near vision and eye strain. Both conditions are typically corrected with spectacles, while myopia can also be treated through surgical procedures like LASIK in some cases.
![MYOPIA [Short Sight]](https://image.slidesharecdn.com/refrectiveerror-170329005749/85/Refrective-error-opthalmology-3-320.jpg)
![MYOPIA [Short Sight]
• It is that dioptric
condition of the eye
in which with the
accommodation at
rest, incident parallel
rays of light come to
a focus anterior to
the light sensitive
layer of retina.](https://image.slidesharecdn.com/refrectiveerror-170329005749/85/Refrective-error-opthalmology-4-320.jpg)
![TYPE OF MYOPIA [Short Sight]
Congenital [developmental] myopia
• • It is present at birth.
• • It is stationary usually.
• • It may be unilateral or bilateral.
• • Bilateral myopia may be associated with convergent squint.
Simple myopia
• • It is the most common type of myopia.
• • There are no degenerative changes in the fundus.
• • It does not progress after adolescence when a
• degree of –5 or –6 D is attained.
Pathological myopia
• • It is a type of degenerative and progressive myopia.
• • It begins at the age of 5-10 years and increases steadily](https://image.slidesharecdn.com/refrectiveerror-170329005749/85/Refrective-error-opthalmology-8-320.jpg)
![HYPERMETROPIA [Far Sight]](https://image.slidesharecdn.com/refrectiveerror-170329005749/85/Refrective-error-opthalmology-11-320.jpg)
![• HYPERMETROPIA [Far
Sight]
• It is that dioptric
condition of the eye in
which with the
accommodation at rest
the incident parallel rays
of light come to a focus
posterior to the light
sensitive layer of the
retina.](https://image.slidesharecdn.com/refrectiveerror-170329005749/85/Refrective-error-opthalmology-12-320.jpg)
Refrective error (opthalmology)
- 2. • EMMETROPIA • It is the normal optical condition of the eye. • The eye is considered to be emmetropic when incident parallel rays of light from infinity come to a focus on the retina (fovea centralis) From: Basic opthalmology 4th edition, page 48
- 4. MYOPIA [Short Sight] • It is that dioptric condition of the eye in which with the accommodation at rest, incident parallel rays of light come to a focus anterior to the light sensitive layer of retina.
- 5. symptom • Indistinct distant vision is the most common symptom. Usually the young children are unable to see the blackboard clearly. • Black spots are seen floating before the eyes. • There is discomfort after near work. • Flashes of light may be seen.
- 6. Signs • May come with Prominent eyes, large pupil and deep anterior chamber • Apparant divergent squint may be present. • Fundus examination (cont.)
- 7. Macula • Foster Fuch’s flecks—These are dark pigmented circular areas of intrachoroidal haemorrhages. Peripheral Fundus • Cystoid degeneration of or a serrata and tesselated (tigroid) fundus may be present. • Weiss reflex streak is seen due to detachment of vitreous at the posterior pole. • Holes and tears in the retina may be present peripherally From: Basic opthalmology 4th edition, page 49
- 8. TYPE OF MYOPIA [Short Sight] Congenital [developmental] myopia • • It is present at birth. • • It is stationary usually. • • It may be unilateral or bilateral. • • Bilateral myopia may be associated with convergent squint. Simple myopia • • It is the most common type of myopia. • • There are no degenerative changes in the fundus. • • It does not progress after adolescence when a • degree of –5 or –6 D is attained. Pathological myopia • • It is a type of degenerative and progressive myopia. • • It begins at the age of 5-10 years and increases steadily
- 9. Treatment • Spectacles—Myopia is treated by prescribing suitable correcting spherical concave lenses for constant use
- 10. Cont. care of eyes- Proper position, correct distance from the book (about 25 cm) while reading. Operative • i. Radial keratotomy/ Excimer laser/LASIK
- 12. • HYPERMETROPIA [Far Sight] • It is that dioptric condition of the eye in which with the accommodation at rest the incident parallel rays of light come to a focus posterior to the light sensitive layer of the retina.
- 13. Symptoms These are noticed specially in the evenings after close work. • There is blurring of vision for near work. • There may be frontal headache and eye strain. • Burning and dryness in the eyes are usually present. From: Basic opthalmology 4th edition, page 51
- 14. Signs • Presented with small eye as a whole. • Accommodative convergent squint may be present. • Fundus examination: I. It may show no abnormality. II. A bright reflex, i.e. watered silk appearance may be seen. III. Pseudopapillitis, i.e. hyperaemic disc with blurred margin may be present which is similar to papillitis From: Basic opthalmology 4th edition, page 51