Direct ophthalmoscopy

normal fundus , the retina how it works & how it is visualised is described here.
the procedure of direct ophthalmoscopy how the image is seen.
Abnormalities of retina how are they seen.

1. GUIDE-DR SURAJKUMAR KURIL SIR DIRECT OPHTHALMOSCOPY -DR PRATIK KISHAN LAKHMAWAR

2. Contents Introduction History Direct ophthalmoscope Optics Distant direct ophthalmoscopy Procedure of direct ophthalmoscopy Normal fundus

3. What are the different methods used for fundus examination?

4. Introduction It is handheld instrument used to examine the fundus of eye. It is the most commonly practiced method for routine fundus examination. It is used to examine central 7 to 10 degree of retina “The physician using a direct ophthalmoscope is like a one-eyed Eskimo peering into an igloo from the entryway with a flashlight.”

5. History It was invented by Hermann Von Helmholtz in 1851 .

6. Optics Convergent beam of light is reflected on to patients retina. The emergent rays from patients retina reach the observer through the viewing hole present in the ophthalmoscope. If the observer is not emmetropic then the correcting lenses must be interposed which are present in the ophthalmoscope.

7. How is the image formed? The image formed on observers retina is- Erect Virtual 15 times magnified (in emmetropes)

8. Procedure It should be performed in semi dark room. Ideally the pupils should be dilated with mydriatic agent. Patient should be looking straight.

9. Position of examination The subject should be examined in sitting or lying down position. While examining the left eye of the subject the examiner should be on left side of the subject and should hold the instrument in the left hand and use left eye. And while examining right eye stand on right side ,hold the instrument in right eye and use right eye.

10. What is distant direct ophthalmoscopy? The ophthalmoscope should be kept at a distance of 20-25 cm from the patient’s eye. Normally a red reflex is seen at the pupillary area. It is used to examine the condition of different media of the eye.

11. Uses Opacities in the ocular media are seen as dark spots in the red glow at the pupillary area. The plane of the opacities can be assessed by asking the patient to move the eye from side to side while the examiner is observing the pupillary glow (based on parallax principle). Opacities in front of the pupil move in the direction of eye movement. O pacities in the pupillary plane do not move. Os pacities behind the pupillary plane move opposite the direction of eye movement.

12. Once the red reflex is seen on distant direct ophthalmoscopy observer should move as close to the patients eye as possible(it should be at the anterior focal palne of the patients eye i.e. 15.4 mm from the cornea. Once the retina is focused details should be examined like disc, blood vessels, macula etc.

13. Parts of direct ophthalmoscope Body- To hold the battery. The body has switch with a rheostat that can control illumination. Head- Eyepiece Lens rack Power dial Filter selector

14. Direct ophthalmoscope consist of two systems

15. Different filters Slit diaphragm- Provided to allow slit lamp type observation of elevated retinal lesions.

16. Small circle Allows quick entry into small, undilated pupils.

17. Half-circle diaphragm Used to reduce reflections by limiting the illumination beam. It is also used to observe some fine retinal details. It is used to avoid fundus reflections while examining.

18. Red-free filter Lack of red light makes the red elements very dark so that vessels & pin point haemorrhages stand out. It is also used to differentiate between retinal & choroidal lesions.

19. Cobalt blue filter Used to enhance visibility of flourescein angiography and it is also used as hand held light source for flourescein staining of cornea.

20. Fixation star For locating lesions For measuring eccentric fixation

21. Normal fundus The fundus of the eye is the interior surface of the eye opposite the lens and includes the retina, optic disc, macula, fovea, and posterior pole. The term fundus may also be inclusive of Bruch's membrane and the choroid.

22. Normal fundus

23. What is RETINA? Retina is the innermost tunic of the eye. It is thin,transparent , delicate membrane. It is the most developed tissue of the eye.

24. Fundus examination is used for Routinely used to assess and diagnose vitreo -retinal diseases such as diabetic retinopathy, hypertensive retinopathy, retinal tear and detachment, macular hole retinal haemorrhages, retinal artery and vein occlusion, Choroidal tumour, macular oedema. Examine the extent of the defects, abnormalities to plan a proper treatment. Evaluate the Success of the treatment.

25. Appearance of normal fundus Appearance - r - Orange to Vermilion Factors Responsible- 1)Amount of pigment in the Choroid 2)hexagonal epithelium of Retina 3)Choroidal vasculature.

26. optic disc artery vein optic cup macula

27. Optic disc Optic disc- It’s a Ophthalmoscopic view of nerve head , while Papilla is the term for Microscopical sections. Its an insensitive area in Retina where Ganglion cell axons exit to form optic nerve. Location- Nasal to Geometrical axis Diameter- 1.5 mm(1 Disc Diopter )

28. Colour- Pale red or Yellowish red tint Normal colour of the disc is due to Axonal bundles – transparent Transmit the light Reflected by disc capillaries Disc appears pale red to yellowish tint

29. Shape- Round or vertically Oval Edges- Regular Physiological Cup- It’s a depression seen in the disc. The size of Physiological Cup not affected by Age Or Hypermetropia . Vessels- Central Retinal artery and vein emerge through its centre. Normal C/D Ratio—0.3-0.5

30. Physiological cup At the centre of the optic disc, there is a short funnel shaped depression from which retinal vessels appear to emerge. 15% optic discs do not show physiological cupping. Nasal border is steeper than temporal border. C/D ratio- 0.3-0.5 Depth of cup depends upon size, shape, obliguity and vascularity of disc. Size of physiological cup is not affected by age or hypermetropia.

31. Macula Diameter-5.5 mm Location- 2 DD temporal to disc Colour-Yellow Function- Photopic vision and Colour vision Macular region is supplied by twigs of superior and inferior temporal arteries, also by cilioretinal arteries.

32. Fovea It is the centre of macula. Fully developed after 4 years. Thick basement membrane. Prone for macular holes.

33. Foveola Centre of Fovea-Foveola Foveola- It is small ,circular, area of deeper red than surrounding fundus. Foveola has only Cones, No Rods. Centre of foveola- Umbo , which is seen as bright spot of light on ophthalmoscopy called as Foveal reflex. Vision is most acute at foveola. Foveal avascular zone- is devoid of retinal blood vessels. It is 0.4-0.6mm in diameter.

34. Other uses of direct ophthalmoscope Pupil- Pupil can be evaluated by comparing size & shape. Anterior segment- With +13 to +15D lens in ophthalmoscope cornea, lids, sclera, lashes & iris can also be examined. Vitreous- With +6 to +7D lens vitreous floaters & opacities can be examined

35. Advantages

36. Disadvantages

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