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Ophthalmoscopy by doctor Rahul gupta.pptx

Ophthalmology topic ophthalmoscopy

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Ophthalmoscopy
INTRODUCTION Ophthalmoscopy is a clinical examination of interior of the eye by the means of ophthalmoscope Primarily done To assess the state of fundus Detect the opacities of ocular media Methods Distance direct ophthalmoscopy Direct ophthalmoscopy Indirect ophthalmoscopy
History • Babbage invented 1st ophthalmoscope in 1848 • Hermann von Helmholtz revolutionized the ophthalmoscope in 1850. The inventor of the direct ophthalmoscope • 1946 – Charles Schepens- MODERN BINOCULAR INDIRECT OPHTHALMOSCOPE
Distant Direct Ophthalmoscopy • Performed routinely before the direct ophthalmoscopy • Performed with the help of a self-illuminated ophthalmoscope
Procedure • The light is thrown into patient's eye sitting in a semi-darkroom, from a distance of 20-25 cm and the features of the red glow in the pupillary area are noted.
Applications of distant direct ophthalmoscopy i. To diagnose opacities in the refractive media . Any opacity in the refractive media is seen as a black shadow in the red glow. The exact location of the opacity can be determined by observing the parallactic displacement. For this, the patient is asked to move the eye up and down while the examiner is observing the pupillary glow. • Opacities in the pupillary plane remain stationary • Opacities in front of the pupillary plane move in the direction of the movement of the eye • Opacities behind it will move in opposite direction
ii. To differentiate between a mole and a hole of the iris. • A small hole and a mole on the iris appear as a black spot on oblique illumination. • On distant direct ophthalmoscopy, the mole looks black (as earlier)but a red reflex is seen through the hole in the iris. iii. To recognize detached retina or a tumour arising from the fundus • A greyish reflex seen on distant direct ophthalmoscopy indicates either a detached retina or a tumour arising from the fundus.
Direct Ophthalmoscopy • Most commonly practised method for routine fundus examination
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 • However, if the patient or/ and the observer is/ are ametropic, a correcting lens (equivalent to the sum of the patient's and observer's refractive error) must be interposed (from the system of plus and minus lenses, inbuilt in the modern ophthalmoscopes).
DIRECT OPHTHALMOSCOPE
Parts : • Handle • Head with a light source • Peep hole with a set of built in dial-up lenses • Filter
Image • In direct ophthalmoscopy, the image is erect, virtual and about 15 times magnified in emmetropes (more in myopes and less in hypermetropes).
Technique • Performed in a semi-darkroom • Patient seated and looking straight ahead • While the observer standing or seated slightly over to the side of the eye to be examined • Patient's right eye should be examined by the observer with his or her right eye and left with the left eye. • The observer should reflect beam of Light from the ophthalmoscope into patient's pupil. • Once the red reflex is seen the observer should move as close to the patient's eye as possible (theoretically at the anterior focal plane of the patient's eye, i.e. 15.4 mm from the cornea). • Once the retina is focused the details should be examined systematically starting from disc, blood vessels, the four quadrants of the general background and the macula
Indirect Ophthalmoscopy
Prerequisites • Darkroom • Source of light • Concave mirror or self-illuminated indirect ophthalmoscopeConvex lens (now-a-days commonly employed lens is of +200) • Pupils of the patient should be dilated
Optical principle • The principle of indirect ophthalmoscopy is to make the eye highly myopic by placing a strong convex lens in front of patient's eye so that the emergent rays from an area of the fundus are brought to focus as a real, inverted image between the lens and the observer's eye, which is then studied
Image • Real, inverted and magnified. • Magnification of image depends upon the dioptric power of the convex lens, position of the lens in relation to the eyeball and refractive state of the eyeball. • About 2.5 times magnification and 35° or 8 disc-diameter field of view is obtained with a +200 lens. With a stronger lens, image will be smaller, but brighter and field of vision will be more.
Technique • Patient 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 patient's eye from an arm's distance (with the self- illuminated ophthalmoscope). ln practice, binocular ophthalmoscope with head band or that mounted on the spectacle frame is employed most frequently • Keeping his or her eyes on the reflex, the examiner then interposes the condensing lens ( +20D, routinely) in the path of beam of light, close to patient's eye, and then slowly moves the lens away from the eye (towards himself) 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, e.g. to examine inferior quadrant (around 6 O'clock meridian) the examiner stands towards patient's head (12 O'clock meridian) and so on. By asking the patient to look in extreme gaze, and using scleral indenter, the whole peripheral retina up to ora serrata can be examined.
Application • Indirect ophthalmoscopy is essential for the assessment and management of retinal detachment and other peripheral retinal lesions.
Difficulties in indirect ophthalmoscopy l. Difficult, requires hours of practice. 2. Reflexes from the corneal surface can be decreased by holding the condensing lens at a distance equal to its focal length from the anterior focus of the eye. 3. Formation of reflexes by the two surfaces of convex lens can be eliminated by slightly tilting the lens and use of aspheric lens
Advantages l. Visualization through hazy media is possible due to strong in built illumination system. 2. Field of view is much larger than direct ophthalmoscopy. 3. Examination of peripheral retina up to ora serrate is possible. 4. Depth perception of the lesion is possible due to stereopsis with binocular indirect ophthalmoscope. 5. Visualization of fundus in very high refractive error is also possible, where it may not be possible to focus the lesion with direct ophthalmoscope
Ophthalmoscopy by doctor Rahul gupta.pptx