POSTERIOR SEGMENTS EXAMINATION BY OPHTHALMOSCOPE.pptx

Ophthalmoscopy is a procedure which is done by ophthalmoscope.
It is a clinical examination of the internal structure of the eye.
Detection of fundus (optic disc/optic cup, macular region, posterior retina) and the opacities of ocular media.
Invented by Babbage in 1848 and re-invented by Von Helmholtz in 1850.

1. OPHTHALMOSCOPE MRS. MEGHNA VERMA

2. CONTENTS INTRODUCTION TYPES DISTANT DIRECT OPHTHALMOSCOPY DIRECT OPHTHALMOSCOPY INDIRECT OPHTHALMOSCOPY ADVANTAGES DISADVANTAGES

3. INTRODUCTION Ophthalmoscopy is a procedure which is done by ophthalmoscope. It is a clinical examination of the internal structure of the eye. Detection of fundus (optic disc/optic cup, macular region, posterior retina) and the opacities of ocular media. Invented by Babbage in 1848 and re-invented by Von Helmholtz in 1850.

4. TYPES

5. DISTANT DIRECT OPHTHALMOSCOPY It should be performed for a rough examination. It gives a lot of useful information. It can be performed with the help of a self-illuminated ophthalmoscope or a simple plain mirror with a hole in the center .

6. PROCEDURE The light is thrown into the patient's eye with the patient sitting in a semi dark room from a distance of 22 to 25 centimeter . At the end, the features of the red glow in the pupillary area are present.

7. DIRECT OPHTHALMOSCOPY The modern direct ophthalmoscope works on the basic principle of glass plate ophthalmocope . Direct Ophthalmoscope introduced by Von Helmholtz.

8. DO can be divided into 2 parts : 1. The illumination system An electric incandescent lamp An aperture Two lenses A small, 45° mirror 2. The viewing system

9. OPTICS A convergent beam of light is reflected into the patient's pupil. The emergent rays from any point on the patient's fundus reach the observer's retina through the viewing hole in the ophthalmoscope. The emergent rays from the patient's eye are parallel and brought to focus on the retina of the emmetropic observer, when accommodation is relaxed.

10. Contd.... If patient/observer is not emmetropic then rays may not focus on the observer retina. In such cases, compensation lenses can be used (plus/minus lenses are incorporated) to focus the rays on the observer retina.

11. In a hypermetropic patient, the emergent ray from the illuminated area of retina, will be divergent and thus can be brought to focus on the observer's retina by the help of a convex lens. In a myopic patient, the emergent rays will be convergent and thus can be brought to focus on the observer's retina by the help of a concave lens.

12. Features of image formation The image is erect and virtual and about 14 to 15 times magnified. Field of Vision Field of vision is always smaller than the field of illumination.

13. PROCEDURE OF DO It should be performed in a semi-dark room with a patient seated and looking straight. And, the observer is standing or seated slightly over to the side of the eye to be examined. The patient's right eye should be examined by the observer with his or her right eye and the patient's left eye with the examiner 's left eye. The observer should reflect beam of light from the ophthalmoscope into patient's pupil.

14. Once the red reflex is seen, the observer should move as close to the patient's eye as possible. The direct ophthalmoscope should be focused by moving the dial for the Reskoss disc, which has several plus and minus power. Once the retina is focused, the details should be examined systematically starting from the optic disc, blood vessels and four quadrants and the macula.

15. INDIRECT OPHTHALMOSCOPY It is introduced by NAGEL in 1864. It is now a very popular method for examination of the posterior segment of an eye.

16. OPTICS To make the eye highly myopic by placing a strong convex lens in front of the patient's eye so that the emergent rays from an area of the fundus are brought to focus as a real and inverted image between the lens and the observer’s eye.

17. Features of image formation The image is real inverted and magnified and five times magnification is obtained . Total magnification depends on lens power ( inversly proportional) and observation distance. Stronger the lens, less magnified image but wider field of view. Field of vision The field of vision is always larger than the field of illumination. The size of the pupil does not affect the size of field of vision.

18. PROCEDURE The procedure is explained to the patient. He or she is made to lie in the supine position with one pillow on a bed or couch and instructed to keep both eyes open. The examiner throws the light into the patient's eye from an arm distance with the self-illuminated indirect ophthalmoscope. Ophthalmoscope with head band or that mounted on the spectacle frame is used most frequently. Keeping the eyes on the reflex, the examiner then interpose the condensing lens plus 20 dioptre (in routine) in the path of beam of light close to the patient's eye.

19. Now, slowly moves the lens away from the eye until the image of the retina is clearly seen. The examiner moves around the head of the patient to examine different quadrants of the fundus. He or she has to stand opposite the clock hour position to be examined such as to examine inferior quadrant, the examiner stands toward the patient's head. By asking the patients to look in extreme gage, and using scleral indenter, the whole peripheral retina up to ora sarata can be examined.

20. ADVANTAGES OF IO Larger field of retina is visible. Lesser distortion of the image of the retina. Easier to examine in the patients eye movements are present. Easy visualization of the retina anterior to equator. It gives a 3D View of the retina with depth of focus. It is useful in hazy media.

21. DISADVANTAGES OF IO Magnification in indirect ophthalmoscopy is 5 times where in direct ophthalmoscopy it is 15 times. It is impossible with very small pupils. The patient is usually more uncomfortable with the intense light. The procedure is more cumbersome. Reflex sneezing can occur on exposure to bright Light.