SLIT LAMP

BIOMICROSCOPY,SLIT LAMP DETAILS

1. Slit lamp biomicroscopy Presented by Subham kumar B.Optom 2 nd year 2017 th batch Ridley college of optometry jorhat assam .

2. Presentation layout Introduction History Principle Optics Types Instrumentation Filters Routine examination Methods of illumination Illumination techniques used in contact lens

3. Uses of slit lamp References Thank you

4. Introduction Slit-lamp is the most important piece of equipment in the present day ophthalmologist’s armamenterium Slit-lamp are used in the examination of the anterior segment of the eye Biomicroscope derives its name from the fact that it enables the practitioner to observe the living tissue of eye under magnification Its not only provides magnified view of every part of the eye but also allows quantitative measurements and photography of every part of documentation

5. History Purkinje, in 1823, attempted to develop a type of slit-lamp by using one hand held lamp to magnify and another hand held lens to focus strong oblique illumination De wecker , in 1863, device a portable ophthalmomicroscope that combine a small monocular microscope Albert and Greenough , in 1891, developed a binocular microscope which provided stereoscopic view

6. Gullstrand, in 1911, introduced the illumination system which had for the first time a slit diaphragm in it Hans goldmann , in 1933, improvised the biomicroscope in which all the vertical and horizontal adjustments for both the lamp and the slit-beam were placed on a single mechanical stage Littmann , in 1950, introduced the new optical principle for the biomicroscope . He incorporated the rotatory magnification changer based on the principle of galilean telescope

7. Principle A narrow slit beam of very bright light produced by lamp. This beam is focused onto the eyes which is then viewed under magnification with control illumination

8. Optics It work on the same principle as a compound microscope The objective lens is towards the patient, whose eyes form the object The objective lens consists of two plano -convex lenses with their convexities put together providing a composite power of +22D The eyepiece is +10 to +14D and is toward the examiner

9. Types There are 2 types of slit-lamp biomicroscope : Zeiss slit-lamp biomicroscope Haag- streit slit-lamp biomicroscope

10. Instrumentation

11. 1.Mechanical support: Forehead rest Chin rest Fixation target Power supply unit Locking unit 2.Observation system: Binocular eyepiece Camera or video adapter Observation tube

12. 3.Illumination system: Lamp housing unit Slit width and height control Neutral density filter Cobalt blue filter Red free filter Field size control Diffuser Prism

13. Mechanical system Joystick arrangement: -movement of microscope and illumination system towards and away from the eye and from side and side is achieved through Joystick arrangement Up and Down movement arrangement: - obtained through some sort or screw devices Patient support arrangement: -vertically movable chin rest and the head rest

14. Fixation target: -a movable fixation target greatly facilitates the examination under some conditions Mechanical coupling: -provides a coupling of microscope and the illumination system along a common axis of rotation that coincides their focal plane Magnification control : -including two or pair of readily changeable objectives lenses and two sets of eyepieces

15. Observations system It consists of 2 optical elements: An objective An eyepiece It presents to the observer an enlarged image of near object The objective lens consists of two plano -convex lenses with their convexities put together providing a composite power of +22D The eyepiece lens has a +10D To overcome the problem of inverted image produce by compound microscope, slit-lamp microscope uses a pair of prism between the objectives and eyepiece to reinvent the image

16. Illumination system It consists of: Variable light intensity: low, medium and high Height: adjustable slit height Angle: variable angle form with the observation system A bright, focal source of light with a slit mechanisms The beam of light can be changed in intensity, height, width, direction or angle and color during the examination with the flick of lever

17. Filters used in slit-lamp biomicroscopy Filter Typical symbol Use Cobalt blue Blue filled circle Enhances the view of fluorescein dye in the tear film of the eye Green filter(red free filter) Green filled circle Used to enhances the view of blood vessels and the haemorrhage Neutral density Circle with hashed lines Decrease the maximum brightness for photosensitive patients Yellow Yellow filled circle For good contrast enhancement Diffuser May be a flip up filter placed on the illumination source Used for general observations of the eye Heat absorbing Build into most slit-lamp Decreases patient discomfort

18. Slit-lamp routine

19. Slit lamp routine 1. Patient adjustment: Patient should be positioned comfortably in front of the slit lamp and his/her chin resting on the chin rest and forehead opposed to headrest

20. 2. Instrument adjustment: The height of the table housing the slit lamp should be adjusted according to patient’s height The microscope and illumination system should be aligned to the patient’s eye to be examined Fixation target should be placed at the required position

21. 3.Beginning slit-lamp examination: some points to be kept in mind are: Examination should be carried out in semi-dark room so that the examiner’s eyes are partially dark adapted to ensure sensitivity to low intensities of light Medications like ointments and anesthetics eye drops produce corneal surface disturbances There should be a minimum exposure of retina to light

22. Diffuse illumination Set-up: Approximately 30-45 degrees between light and microscope The wide open slit width is used here The magnification used here is low to medium Medium to high illumination is used The filter used here is diffusing

23. Observe: Overall view of lids and lashes, conjunctiva, cornea, sclera and pupil Lens fitting characteristics such as centration and movement

24. Direct illumination Set-up: Observation and illumination system are focused at the same time Medium to high illumination is used here Low to medium magnification can be used to observe with cornea responses variation in the width on height source will give the following: Optic section Parallelopiped Conical beam

25. Optic section Produced very narrow slit-beam The optical section produced resembles a knife like histological section of tissue focused(cornea, lens) The whole tissue can be examined by moving the slit-beam and simultaneous focus of the microscope across the surface

26. Observe: Highlights the different layers of cornea Nerve fibers Infiltrates Blood vessels

27. Parallelopiped It is observe using a wider beam Allow a more wider field of view for observation Allows a more extensive examination of the corneal layers

28. Observe: Corneal stroma Epithelial breakdown Lens surface endothelium

29. Conical beam Small, bright circular light source Used with high magnification Best used in a completely darkened room Observe: Flare Cell debris Pigmentation

30. Indirect illumination Set-up: Observation and illumination system are not focused at the same point 30-45 degrees angles between light and illumination Low, medium or high illumination is used Slit-beam can be offset by rotating the prism or mirror at the illumination system

31. Observe: Corneal microcysts Epithelial cells Vacuoles Iris pathology

32. Retro-illumination Set-up: The object of interest is illuminated by light reflected from the structures behind it Vary angle between light and microscope Slit-beam is offset by rotating a body of the illumination system Moderate beam is used The cornea is illuminated by the light reflected from the iris, lens and fundus

33. Observe: Cornea: neovascularisation , edema, microcysts , vacuoles, and infiltrates Contact lens: front and back surface deposits

34. Indirect retro-illumination: The prism or mirror is offset so that the area under observation is viewed between the focal light beam and the light reflected from the iris or lens

35. . Direct retro-illumination : The prism or mirror is moved so that the light reflected from the iris or lens is directly aligned with the area of observation

36. Specular reflection Set-up: 60 degrees angle between light and microscope Parallelepiped beam is used Angle of incidence is equal to angle of reflection Observe: Individual cells of endothelium Tear film debris Tear film lipid layer

37. Sclerotic scatter Set-up: Illumination of the cornea by total internal reflection of a wide angle light source The light beam is directed at the limbal region Observe: Epithelial edema Corneal scar Foreign bodies in the cornea

38. Oscillating illumination of koeppe In this, the slit-beam is given an oscillatory movement by which it is often possible to see minute objects or filaments especially in the aqueous which would otherwise escape detect detection

39. Illumination techniques used in contact lens

40. Diffuse illumination Used to observe contact lens fitting performance

41. Broad beam illumination Used to observe debris beneath the contact lens

42. Specular reflection Used to observe lens front surface wetting

43. Retroillumination Used to observe contact lens front and back surface deposits

44. Uses of slit lamp biomicroscopy Diagnostic: Anterior and posterior segment disease Dry eye Procedures Applanation Tear evaluation Gonioscopy Contact lens fitting

45. Therapeutic: Foreign bodies removal epilation

46. References AK Khurana , comprehensive opthalmology , page no 567-568, 6 th edition AK Khurana , theory and practice of optics and refraction, page no 351-361, 3 rd edition Theodore p. grosvenor , primary care optometry, page no 140-142 https://www.aao.org https://www.academy.org.uk www.slideshare.com/slit_lamp_illumination_techniques www.slideshare.com/slit_lamp_biomicroscopy www.slideshare.com/slit_lamp_biomicroscopy_and_illumination_techniques

47. Thank you