DIAGNOSTIC SLIT LAMP BIO-MICROSCOPE.pptx
- 1. SLIT LAMP BIOMICROSCOPE MS. MEGHNA VERMA Department of Optometry RAMA University
- 2. CONTENTS INTRODUCTION PARTS OF SLIT LAMP PREPARATION TECHNIQUE METHODS OF ILLUMINATION
- 3. INTRODUCTION In 1911, GULLSTRAND is credited with the invention of slit lamp. Slit lamp is the most important equipment in the present day. Modern slit lamp with its additional device provides qualitative and quantitative measurements and photographic records. Qualitative measurements - magnified view of every part of the eye from cornea to retina. Quantitative measurement - IOP, endothelial cells counts, pupil size, corneal thickness, anterior chamber depth.
- 5. PRINCIPLE A slit beam of very bright light produced by lamp. This beam is focused on to the eye which is then viewed under magnification with a microscope.
- 6. ILLUMIATIO N SYSTEM MECHANICAL SYSTEM OBSERVATIO N SYSTEM PARTS OF SLIT LAMP
- 8. OBSERVATION SYSTEM (MICROSCOPE) It is a compound microscope. It consists of two optical elements i.e. an objective and an eyepiece. It provides to the observer an enlarged view of a near object. An objective lens consists of two plano-convex lens, with their convexities put together, providing a composite power of +22 Dioptre. An eyepiece lens is of + 10 D. In slit lamp, uses a pair of prism is placed between the objective and eyepiece, to re-invert the image. Prism is used to overcome the problem of inverted image, produced by compound microscope.
- 11. ILLUMINATION SYSTEM Illumination system is provide a bright and fine focused adjustable slit of light at the eye. LIGHT SOURCE CONDENSER LENS SYSTEM SLIT & DIAPHRAGM FILTERS PROJECTION LENS MIRRORS & PRISMS
- 14. LIGHT SOURCE Nitra lamp, arc lamp, mercury vapour lamp and halogen lamp. It provides an illumination of 2X 10 to 4 X 10 LUX. CONDENSER LENS SYSTEM Two plano-convex lenses, their convexities put together. SLIT AND DIAPHRAGMS Height & width of slit can be varied by knobs. It provides, examination of fundus and angle of anterior chamber.
- 15. FILTERS Cobalt blue and red free filters. PROJECTION LENS It forms an image of the slit. It keeps lesser the aberration, better the image quality. MIRRORS/ PRISMS Normally arranged vertical axis with either mirror/ prism, reflecting the light along horizontal axis.
- 16. MECHANICAL SYSTEM 1. JOYSTICK ARRANGEMENT 2. UP AND DOWN MOVEMENT ARRANGEMENT 3. PATIENT SUPPORT ARRANGEMENT 4. FIXATION TARGET 5. MECHANICAL COUPLING
- 18. JOYSTICK ARRANGEMENT Movement of the microscope and illumination system towards or away from the eye and from side to side is usually achieved. UP AND DOWN MOVEMENT ARRANGEMENT It moves the whole illumination and viewing system up and down relative to chin rest. PATIENT SUPPORT ARRANGEMENT A vertically movable chin rest and adjust the height of the table.
- 19. FIXATION TARGET A movable fixation target greatly facilitates the examination under some conditions. MECHANICAL COUPLING It not only provides a support but also a coupling of microscope and illumination system along a common axis of rotation.
- 20. BEGINNING OF SLIT LAMP EXAMINATION Examination should be in semi dark room Start with the diffuse illumination Start with the Low magnification Low to medium to high Do not use any medication
- 21. TECHNIQUE OF BIOMICROSCOPY The patient should be positioned comfortably in front of the slit lamp with his/her chin resting on the chin rest and forehead against to head rest. PATIENT ADJUSTME NT The microscope and illumination system should be aligned with the patients eye to be examined. The height can be varied using knobs as per patients height. Fixation target should be placed at the required position. INSTRUMENT ADJUSTMENT
- 22. METHODS OF ILLUMINATION Diffuse illumination Direct illumination Indirect illumination Retro illumination Sclerotic scatter Oscillating illumination
- 23. DIFFUSE ILLMINATION 45 degree angle between light and microscope Fully open slit Diffusing filter Variable magnification (low to medium to high) Variable illumination (medium to high) Overall view of - lids and lashes, conjunctiva, cornea, sclera, iris, pupil
- 24. DIRECT ILLUMINATION Vary angle of illumination Low to high magnification Vary width and height of light source Variable illumination
- 25. Optic Section: Narrow, focused slit. Corneal curvature, corneal thickness.
- 26. Parallelepiped: wider beam observe corneal stroma, epithelial breakdown, lens surface and endothelium.
- 27. Conical Beam: Small, bright, circular light source. Use with high magnification. Used for observation of flare and cells in the anterior chamber.
- 28. INDIRECT ILLUMINATION Observation and illumination systems are not focused at the same point. Vary angle of illumination Slit beam is offset Vary beam width Low to high magnification Valuable for observing: Iris pathology, Epithelial vesicles, Epithelial erosions, Iris sphincter.
- 29. RETRO ILLUMINATION Vary angle of illumination Moderately wide beam Slit beam is offset Medium to high magnification The cornea is illuminated by light reflected from the iris, crystalline lens or fundus. Valuable for observing: Epithelial oedema, Microcysts, Vacuoles, Dystrophies, lens opacities, Contact lens deposits.
- 30. SPECULAR REFLECTION The angle of incident light is equal to the angle of reflected light. Valuable for observing: Endothelial cells, Tear film debris, Tear film lipid layer.
- 31. SCLEROTIC SCATTER Illumination of the cornea by total internal reflection of a wide angle light source. The light beam is directed at the limbal region while observing the cornea. Valuable for observing: Localized epithelial oedema, Corneal scars, Foreign bodies in the cornea.
- 32. TANGENTIAL ILLUMINATION METHOD Large angle of 70 - 80属 between illumination and observation system. Valuable for observing: Iris freckles, Tumours, General integrity of the cornea and iris.
- 33. CLINICAL USES Anterior segment evaluation. Tear evaluation. Measures corneal thickness. Evaluate intra ocular pressure. Examine angle of anterior chamber. Removal of foreign particle. Contact lens fitting. Evaluation of post fitting contact lens. Epilation of lashes.