OPT506 - L01 - Slit Lamp Biomicroscopy 1 2024-25 PDF

History & Symptoms Specialist Optometry Skills OPT506 Dr. Asma Zahidi  Introduction to module & Slit lamp biomicroscopy 1 Dr. Asma Zahidi Ground Rules 1. Be respectful 2. Be ready 3. Be safe  What is Specialist Optometry Skills?...

History & Symptoms Specialist Optometry Skills OPT506 Dr. Asma Zahidi  Introduction to module & Slit lamp biomicroscopy 1 Dr. Asma Zahidi Ground Rules 1. Be respectful 2. Be ready 3. Be safe  What is Specialist Optometry Skills? Optometry General Skills Specialist skills Binocular vision Pediatric vision Contact Lens Low Vision 2 OPT506 Structure - Overview All year (term 1 and 2) 20 credits (200 hours of work)  30 hours of lectures  48 hours of practical sessions  122 hours of independent study Assessments  50% Written exam  50% Practical exam 2 OPT506 Structure - Lectures 1 lecture each week (2 hours) Lecture outline – uploaded on DLE 48 hours before lecture Lecture slides – uploaded on DLE after lecture Contents:  L1 – L5 Initial CL assessment  L6 – L9 Rigid Gas Permeable Lenses (RGP)  L10 – L11 Optics and CL material  L12 – L16 Soft Contact Lens (SCL)  L17 – L18 Low Vision  L19 – L20 CL care and complications 2 OPT506 Practical Session 1 practical session each week (2 hours) Briefing / Demo / Q&A Student 1 Student 2 (50 minutes) (50 minutes) Group 2 9.00 – 9.10am 9.10 - 10.00am 10.00am – 10.50am Group 1 11.05 – 11.15am 11.15am – 12.05pm 12.05 – 12.55pm Be early! Arrive 10 minutes before start time Set up the bay if first of pair – don’t wait! 2 OPT506 Practical Session All sessions in Demo videos uploaded on DLE Hand hygiene very important! Dress code – smart + name tag Short nails and no nail varnish please Clinical workbook and pen Optometry kit + stationary Personal belongings in locker (code 2244) Use the screen to watch demo videos or find info – no phones! Turn equipment off after use – keratometer, SL, bay lights Log out PC before leaving the session Leave bay tidy! 2 OPT506 Structure - Assessments 50% Written exam (13/05/2025)  50 Multiple choice questions 50% Practical exam (3 OSCE Stations + 1 ISCE)  OSCE 03/12/2024 Station 1 - Slit lamp techniques Station 2 – Keratometry and baseline measurements Station 3 – RGP fit assessment (passive) ISCE (27/5/2025 – 28/05/2025) – SCL Aftercare routine 2 GOC Core Competencies https://www.optical.org/en/Education/core-competencies--core- curricula/ Contact lens PDF of GOC CL handbook and CL Specialty Competency on OPT506 DLE Low vision 3.1.3 (a) Ability to assess visual function in patients with visual impairment (Visions) 3.1.3 (b) Ability to assess visual function in patients with visual impairment (Pupils, BV and fields) 9.1.1 Ability to take an appropriate history of visual impairment patient 9.1.3 Ability to accurately quantify visual impairment and relate it to the underlying pathology and functional consequences 9.3.2 (a) Ability to advise on the use of optical and non-optical aids (Optical aid) 9.3.2 (b) Ability to advise on the use of optical and non-optical aids (Non-optical aid) 2  OPT506 Intended learning outcomes At the end of this module, you should be able to: 1. Demonstrate the ability to use a range of different instrumentation and techniques for assessment of the anterior eye 2. Demonstrate an understanding of the materials and design of different forms of contact lenses 3. Evaluate and select appropriate lenses for different refractive problems and assess and interpret the fit of different types of contact lenses. 4. Demonstrate appropriate aftercare in contact lenses. 5. Demonstrate an understanding of magnification and analyse alternative techniques in the management of visual impairment 6. Evaluate and select appropriate optical and non-optical aids to manage a patient with visual impairment 7. Develop an appropriate management plan for contact lens wearing patients. 2 Slit Lamp Biomicroscopy 1 Dr. Asma Zahidi Intended learning outcomes By the end of this topic, you should be able to: Demonstrate competent use of the standard slit lamp and its accessory equipment. Employ all the functions of the slit lamp and use accessory equipment when indicated. Perform slit lamp bio-microscopy of the eye and adjacent structures using appropriate illumination techniques. Interpret the findings from the anterior eye assessment accurately. Anatomy of the anterior eye Advantage of slit lamp use Gold standard device for the assessment of the anterior segment of the eye This is because they provide:  Excellent image quality  Stereoscopic image  Flexible illumination  Flexible magnification  Even more uses when attachments are added  Main components of a slit lamp Illumination system Patient support Chin rest Forehead rest Observation system Observation System Eyepiece Mignification Magnification Medium (x10-16) Low (6x) Closer examination General Overview of the Eye Conjunctiva – bulbar and palpebral Lids Limbus Bulbar conjunctiva Tear ducs Cornea / limbus Meibomina glands Corneal layers Tears Anterior chamber Iris Cystalline lens Magnification High (20-25x) Structures Epithelium Stroma Endothelium 21 Magnification Very High (30-40x) Details Epithelium Stroma Endothelium Vacuoles Striae Polymegatism Microcysts Folds Blebs Dystrophies Dystrophies Illumination system Slit beam height – Haag-Streit typesystem The height of the beam is controlled at the top of the illumination arm. A mm gauge displays the This dial controls the height height of the slit beam of the slit beam 24 Diffuser filter Essential part of the slit lamp Ground glass filter used to scatter the light so that there is not a focused beam on the eye Used for general viewing Slit Lamp filters Heat reduction filter Neutral density filter Cobalt blue filter + Wratten filter Red free filter Wratten 12 filter A yellow filter that is placed in front of the observation system to enhance the contrast of fluorescein Generally held in place by hand but some newer slit-lamps have this in-built  When do we use a slit lampbio-microscope? Gonioscopy Fundoscopy Pachymetry Anterior eye health assessment Contact tonometry Laser photocoagulation Contact lens fitting – routine History & symptoms Baseline measurements Keratometry Anterior eye assessment Selection of lens Insertion of lens Fit assessment Over refraction Prescribe / refit Slit lamp and contact lens fitting To establish patient suitability for CL wear Recording baseline measurements before CL wear Monitoring the CL fitting process During all subsequent patient visits ‒ scheduled & unscheduled CL fit assessment Assessment of the CLs (condition, surface properties, wetting, etc.) Assessment of ocular integrity Things to remember… 1. Wipe down the slit lamp 2. Hand hygiene 3. Focusing – emmetrope /fully corrected should be within ±0.50D  Slit lamp examination techniques - overview Technique Purpose Direct illumination Diffuse illumination General overview, Contact lens fit Basic Parallelepiped Main examination method for all corneal layers (NOT Basic endothelium) Optic section Detailed observation Basic Indirect illumination Specular reflection Advanced Endothelium, Tear film Advanced Conical beam Anterior chamber Advanced Sclerotic scatter General overview of the cornea Retro-illumination Specifically for corneal oedema and pathological changes Advanced Vessels and Neovascularization Van Herick’s Technique Anterior Chamber Angle assessment (ACA) Anterior chamber  Slit lamp techniques (Direct vs Indirect Illumination) Direct Illumination Indirect Illumination The structure that is The structure that is adjacent to the illuminated is also observed illuminated structure is observed Symbols Observation Illumination  Slit lamp settings Slit width Narrow slit Parallelepiped Maximum slit (Optic section) (Diffuse) Slit height Shortest slit Conical beam Maximum height Diffuse illumination SETUP: Angle between microscope and illumination system should be 30-45°. Slit width should be widest. Filter to be used is diffusing filter. Magnification: low to medium Illumination: medium to high.  Diffuse illumination OBSERVATION: Gives a good overall picture of the eye, but no fine details. It is used primarily for a general survey of the eye. Observe: eyelids, lashes, conjunctiva, sclera, pattern of redness, iris, pupil, gross pathology, and media opacities  Parallelepiped SETUP: Angle: Light source is approximately 40- 60° from straight ahead position. Slit: Narrowing the beam to 1-2mm in width to illuminate a rectangular area of cornea. Filter: Start with no filter Magnification: 16x Illumination: medium Microscope is placed directly in front of patients cornea.  Parallelepiped OBSERVATION: Detect and examine corneal structures and defects Higher magnification than that used with wide beam illumination is preferred to evaluate both depth and extent of corneal scarring or foreign bodies. Corneal nerves appear under higher magnification as fine white silk threads usually branching into a Y (seen mostly in middle third of stroma).  Optic section SETUP: Angle: Light source is approximately 45- 60° from straight ahead position. Slit: Thinnest slit possible (be careful, if too thin the illumination will turn off!) Magnification: Medium to maximum Illumination: maximum (important!) Optic section is a very thin parallelepiped and optically cuts a very thin slice of the cornea.  Optic section OBSERVATION: Used to localize: Nerve fibers, Blood vessels, Infiltrates, Cataracts, To discover thickening, thinning, and/or distortions in the corneal contour. To determine the depth of foreign bodies or opacities in the corneal substance. (a percentage of the total corneal thickness) To see a wide slice of stroma. (The angle between the microscope and illuminating arm can be increased.) Parallelepiped vs Optic section Parallelepiped Optic section Where on the surface? How deep (which layer)? Indirect Illumination Techniques Slit lamp examination techniques - overview Technique Purpose Direct illumination Diffuse illumination General overview of ant. eye, Contact lens fit Basic Parallelepiped Main examination method for all corneal Basic layers (NOT endothelium) Optic section Detailed observation of all corneal layers and Basic crystalline lens Indirect illumination Specular reflection Endothelium, Tear film, Crystalline lens surface Advanced Sclerotic scatter Corneal surface Advanced Conical beam Anterior chamber Anterior chamber Retro-illumination Advanced Van Herick’s Technique Anterior chamber Illumination techniques – Specular reflection Initial set up Bring SL in set up position Angle: illumination arm and observation must be equal  E.g. illumination arm 30° = observation arm 30°  Lock illumination and observer arm so that both rotate simultaneously (static angle of 60°)  Move slit lamp until optic section is on bright reflection (Purkinje image) Slit: optic section Filter: none Magnification: start with 10x and increase to max to see details Illumination: medium to max REMEMBER: Law of reflection on a plane mirror (angle of incident ray = angle of reflected ray)  Purkinje image Optic section  Illumination techniques – Specular reflection OBSERVATION: To visualize the integrity of the tear film (lipid layer), corneal and lens surfaces To visualize the endothelium start with lower magnification (10X to 16X). Direct a relatively narrow beam onto the cornea Switch to the highest magnification available Endothelium is best viewed using only one eye. Under specular reflection anterior corneal surface appears as white uniform surface and corneal endothelium takes on a mosaic pattern. Specular reflection – Lipid layer Specular reflection – Corneal Endothelium Specular reflection – Lens surface Illumination techniques – Sclerotic scatter SETUP: DECOUPLED The beam is focused on the limbus. Observer is positioned centrally Angle: 45 – 60° Slit: Narrow slit 0.5mm Filter: No filter Magnification: 10-16x Illumination: Maximum DECOUPLED Decoupling – indirect illumination Two different point of rotation Same rotation point Decoupling – indirect illumination Low mag - direct Low mag - indirect High mag - indirect Illumination techniques – Sclerotic scatter OBSERVATION: Total internal reflection of the incoming light at inner corneal boundaries Scars, foreign bodies, corneal defects Irregularities in the cornea Illumination techniques – Conical beam SETUP: Angle: 45 - 60° Slit: Parallelepiped with 1 – 2mm height Filter: Start with no filter Magnification: Start with medium (10x) and increase to max Illumination: Maximum Principleis same as that of beam of sun light streaming through a room, illuminating airborne dust particles (=Tyndall’s phenomenon).  Illumination techniques – Conical beam OBSERVATION: Focusing: Beam is focused between cornea and anterior lens surface and dark zone between cornea and anterior lens observed. Most useful when examining the transparency of anterior chamber for evidence of floating cells and flare seen in anterior uveitis. Beam on cornea Beam on lens ant. surface Retro-illumination Slit lamp examination techniques - overview Technique Purpose Direct illumination Diffuse illumination General overview of ant. eye, Contact lens fit Basic Parallelepiped Main examination method for all corneal Basic layers (NOT endothelium) Optic section Detailed observation of all corneal layers and Basic crystalline lens Indirect illumination Specular reflection Endothelium, Tear film, Crystalline lens surface Advanced Sclerotic scatter Corneal surface Advanced Conical beam Anterior chamber Anterior chamber Retro-illumination Specifically for corneal oedema and Advanced pathological changes Vessels and Neovascularization Van Herick’s Technique Anterior chamber  Illumination techniques – Direct retro illumination SETUP Decoupled! Iris/lens Retina Angle 30-50° 0 - 10° Slit Parallepiped Parallepiped Max height Height: pupil size Magnification Start with 16x Start with 10x and increase Illumination Medium - high Low - medium DECOUPLED Illumination techniques – Direct retro illumination OBSERVATION: Examination of objects in direct vicinity of corneal areas of reduced transparency  infiltrates,  corneal scars,deposits,  epithelial and stromal defects Used most often in searching for  keratic precipitates  other debris on corneal endothelium. Crystalline lens  water clefts  vacuoles of anterior lens  posterior subcapsular cataract Direct retro illumination from the retina Decoupled! Illumination techniques – Indirect retro illumination OBSERVATION: Infiltrations, small scars, corneal vessels, micro cysts, vacuoles Feature on the cornea is viewed against a dark background Direct vs. indirect retro illumination Direct Indirect Assessment of the anterior chamber angle Slit lamp examination techniques - overview Technique Purpose Direct illumination Diffuse illumination General overview of ant. eye, Contact lens fit Basic Parallelepiped Main examination method for all corneal Basic layers (NOT endothelium) Optic section Detailed observation of all corneal layers and Basic crystalline lens Indirect illumination Specular reflection Endothelium, Tear film, Crystalline lens surface Advanced Sclerotic scatter Corneal surface Advanced Conical beam Anterior chamber Anterior chamber Retro-illumination Specifically for corneal oedema and Advanced pathological changes Vessels and Neovascularization Van Herick’s Technique Anterior Chamber Angle assessment (ACA) Anterior chamber The anterior chamber in numbers 3.15mm V=220µl (2.6 to 4.4mm) 20 to 45° 11.3 to 12.4mm Clinical importance: Changes during life, changes due to refractive error Clinical parameters: Anterior chamber depth (ACD) Anterior chamber angle (ACA) Assessment of the anterior chamber ACA (Anterior chamberangle) ACD (Anterior chamber depth) VanHerick’s – Assessing ACA SETUP: OBSERVATION: The beam is focused on the limbus. Relation between corneal slit image Observer is positioned centrally. and anterior chamber depth System is coupled. To evaluate anterior chamber angle Angle: 60° without gonioscopy Gives grading of the ACA Slit: Optic section Filter: No filter Magnification: Medium (16x) Illumination: Medium to maximum VanHerick’s – Assessing ACA 60° Slit on Slit on cornea iris (focal) VanHerick’s – Grading Grade 4 Grade 3 Grade 2 Grade 1 Grade 0 The distance The distance The distance The distance No distance between the between the between the between the between the posterior surface of posterior surface of posterior surface of posterior surface of posterior surface of the cornea and the cornea and the cornea and the cornea and the cornea and anterior surface of anterior surface of anterior surface of anterior surface of anterior surface of the iris is at least the the iris is one-half the iris is one quarter the iris is less than the iris. The angle is same width of the the width of the slit the width of the slit one quarter the considered closed, slit beam on the beam on the cornea. beam on the cornea. width of the slit and angle closure cornea. The angle is The angle is Angle closure is beam on the has occurred. considered open, considered open, possible. cornea. The angle is and angle closure is and angle closure is considered very very unlikely. unlikely. narrow, and angle closure is likely. Ratio 1:1 or more Ratio 1:0.5 -1 Ratio 1: 0.25-0.5 Ratio 1 < 0.25 closed Estimated angle: Estimated angle: Estimated angle: Estimated angle: Estimated angle: 35 – 45° 20 – 35° 20° 10° closed VanHerrick’s Summary You will use the slit lamp to assess the health of the anterior eye You will use the slit lamp to assess the fit of the CL Anterior eye assessment SL techniques  Direct illumination (Basic)  Indirect illumination (Advance)  Retro-illumination (Advance)  Van-Herick’s(Advance) Diffused illumination – overall assessment of the anterior eye Parallepiped and optics section detailed assessment of tear, cornea, lens Questions?