OPT506 Slit Lamp Biomicroscopy 3 2024-25 Lecture Notes PDF

History & Symptoms Specialist Optometry Skills OPT506 Dr. Asma Zahidi Slit Lamp Biomicroscopy 3 Dr. Asma Zahidi One-time code: XV-RL-YT Lecture outline 1. Revision of anterior eye assessment with white light 2. Tear film assessm...

History & Symptoms Specialist Optometry Skills OPT506 Dr. Asma Zahidi Slit Lamp Biomicroscopy 3 Dr. Asma Zahidi One-time code: XV-RL-YT Lecture outline 1. Revision of anterior eye assessment with white light 2. Tear film assessment with white light 3. Routine of the anterior eye assessment with blue light 4. Recording findings One-time code: XV-RL-YT  A Slit-Lamp Examination Flowchart White light Lid margins/eyelashes Tears/tear film From the outside Conjunctiva: to the inside ‒ Bulbar ‒ Palpebral Limbus Cornea Anterior chamber Iris Crystalline lens One-time code: XV-RL-YT A Slit-Lamp Examination Flowchart White light Blue light + NaFl Lid Tears/tear film margins/eyelashes Cornea Tears/tear film Conjunctiva: Conjunctiva: ‒ Bulbar ‒ Bulbar ‒ Palpaebral (blue ‒ Palpebral and white light) Limbus Cornea Anterior chamber Iris Crystalline lens One-time code: XV-RL-YT A Slit-Lamp Examination Flowchart Blue light + NaFl + wratten filter Tears/tear film Cornea Conjunctiva: ‒ Bulbar ‒ Palpaebral (blue and white light) One-time code: XV-RL-YT Blue light assessment Fluorescein strips Need to be wet with Saline Most common Can also be found in combination with topical anesthetic Fluorescein instillation Invasive Tear Break-Up-Time Set up on the slit lamp is with broad beam illumination Cobalt blue filter in place Wratten 12 filter -- improves the visibility of the Fluorescein Sufficient magnification for entire cornea Ask Px to blink a few times After last blink ask px to keep eyes open for as long as possible Time the length of time it takes before you notice the first break up of tears Appears as black streak in tear film Tear break up time Tear break up time Tear break up time Aqueous tear-deficient Dry eye with Evaporative dry eye decreased wettability dry eye Severe Severe Area Break-Up Spot Break-Up Random Break-Up Mild/Moderate Mild/Moderate NOTE! Use highest illumination when assessing with blue light and NaFl Line Break-Up Dimple Break-Up A Slit-Lamp Examination Flowchart Blue light + NaFl + wratten filter Tears/tear film Cornea Conjunctiva: ‒ Bulbar ‒ Palpaebral (blue and white light) Corneal staining Dot-shaped defects in the superficial corneal layer (epithelium) Visible by staining the tear film with fluorescein and adding a yellow filter Concomitant symptoms: pain, redness of the eye, increased flow of tears (if severe) Start with parallelepiped (mag 16x and highest illumination) Change to optic section (increase mag to 25X – 40x) Corneal staining - aetiology Mechanical — trauma, foreign body, damaged lens, lens edge, material stiffness, thick lens design, Ortho-K lens wear, scleral lens wear Exposure — disruption of tear film and subsequent desiccation Metabolic — hypoxia, hypercapnia (tissue acidosis and desquamation of epithelial cells) Solution induced corneal staining (SICS) seen 2-4 hours after insertion with some SiHy and multi-purpose solution (MPS) combinations Toxic — care regimen hypersensitivity (1-10% hydrogel lens wearers) Allergic — delayed or immediate hypersensitivity reaction Infectious systemic disease, poor general health (e.g. influenza, throat infection) Corneal staining - pattern Classification: Type, Size, Extend Dryness Mechanical cause Toxic cause ► Decompensated ► Removal of cells ► Decompensated Cells Cells ► E.g. 3 and 9 o‘clock ► SICS ► Corneal staining staining Corneal Abrasions: Staining Patterns Corneal Abrasions: Staining Patterns A Slit-Lamp Examination Flowchart Blue light + NaFl + wratten filter Tears/tear film Cornea Conjunctiva: ‒ Bulbar ‒ Palpaebral (blue and white light) Bulbar Conjunctival staining - Also an indication of dry eye - Some dry eye drops (e.g. diquafosol ophthalmic sodium and topical rebamipide) increase mucin secretion and improve conjunctival staining scores - Compare before and after  Lid eversion Get the patient to look down Grasp the upper lid at the base of the lashes with the thumb and forefinger of one hand (H1). Pull down at an angle of 45 degrees (this moves the lashes away from the bottom lid) The other hand (H2) pushes the upper tarsus of the lid downwards with a cotton-tipped bud At the same time gently pulling the lashes out and upwards (H1)  Lid eversion Hold the eyelashes against the skin while doing the examination (remove the cotton bud) Once you have finished the examination – replace the lid Ask the patient to continue to look down when pulling the lid back to its normal position. This will lessen discomfort.  Why do lid eversion??? Cobblestone-like nodules of the palpebral Small deposits of calcium which are conjunctiva arising from irritation brought usually asymptomatic but can cause a about by contact lens wear or solutions. foreign body sensation. Lid eversion Record keeping Record Cards (Contact lens) Draw the staining Grading scale used: pattern seen on the cornea Linear abrasion Superficial G1 Superficial fine punctate staining G1 Label and grade the staining pattern seen on the cornea  Areas of the superior palpebral conjunctiva 1: Upper tarsal area 2: Central tarsal area 3: Lower tarsal area 4: Temporal junctional area 5: Nasal junctional area Reasons for using grading scales In health care disciplines, need to be able to record accurately: To document both physiological and pathological traits To monitor disease To allow another clinician to follow on care To document  The investigative process  The decision-making process Recording by:  Description  Pictorial  Grading scale Difficulties in Descriptions When describing the severity of a condition often words such as mild or severe are used This is subjective One persons mild is another persons moderate Grading scales can be used as a reference point to reduce some of this subjectivity Grading scales Photographic grading scale Drawn grading scale Drawbacks of grading scales Photographic  Immense library needed  Difficult to get precise same manifestation  Different patients  Different perspective (magnification, colour and angles)  Multiple conditions often present disease  Some conditions difficult to photograph Painted / drawn  Lack of realism  Systematic presentation of severity possible Grade this picture CCLRU = Efron grading = Grading Estimate to grade between units Designate system used Additional annotations on pictorial diagram Grading number increases with severity Balance between accuracy and speed Can only cover main conditions In research, grade individual zones Grading In general: Grade 0 : normal, no tissue change Grade 1 : trace, no clinical action required Grade 2 : mild, clinical action may be required Grade 3 : moderate, clinical reaction usually required Grade 4 : severe, action urgently required Only a general suggestion, still dependent on clinician Use the grading scale to grade each part of the eye The Slit-Lamp Examination: Tips for Patient Comfort Issue clear instructions/explanations Instrument-patient-examiner alignment Proficient & skilful slit-lamp usage Use minimum brightness applicable Minimize time taken for each aspect of the examination Examination should flow smoothly & logically Assessment of the tear film Assessment of the tear film Non-invasive methods 1. Non-Invasive Tear Break-Up-Time (NIBUT) 2. Tear thinning time 3. Tear prism height 4. Lipid layer evaluation Invasive methods 1. Tear Break-Up-Time (TBUT) 2. Schirmer test 3. Phenol-red thread test 4. Rose Bengal staining Tear prism height (non-invasive) The tear prism is a tear reservoir running along the lower eyelid margin The thickness of the tears is dependent on the tear volume The tear prism height allows the indirect measurement of tear volume To measure it set up your slit lamp as for Parallelepiped Look at the tear reservoir on the lower eyelid margin Observation system Illumination system Tear prism height (non-invasive) Measured in mm Use an eyepiece graticule (if available) Adjust the height of the slit beam to match that of the tear prism Port and Asaria (1990) give normal heights to be 0.2 to 1.0mm Note in this picture fluorescein has been instilled. This is only so that you can see the tear prism on the picture. The technique is non-invasive -- fluorescein should not be used! Tear Break-Up-Time Measures the stability of the tear film Time taken for the tear film to first break up following a blink Non-invasive tear Break-Up-Time Examine the specular reflection in order to assess when the tear film first breaks Specific grid systems developed for this task See Contact lens Complications (Nathan Efron) pg. 81 Invasive Tear Break Up Time (ITBUT) Using Fluorescein Easiest to assess under clinical environment Not truly representative as Fluorescein destabilizes the tear film Tear Break-Up-Time Measures the stability of the tear film Time taken for the tear film to first break up following a blink Non-invasive tear Break-Up-Time Examine the specular reflection in order to assess when the tear film first breaks Specific grid systems developed for this task See Contact lens Complications (Nathan Efron) pg. 81 Invasive Tear Break Up Time (ITBUT) Using Fluorescein Easiest to assess under clinical environment Not truly representative as Fluorescein destabilizes the tear film Invasive Tear Break-Up-Time Set up on the slit lamp is with broad beam illumination Cobalt blue filter in place Wratten 12 filter -- improves the visibility of the Fluorescein Sufficient magnification for entire cornea Ask Px to blink a few times After last blink ask px to keep eyes open for as long as possible Time the length of time it takes before you notice the first break up of tears Appears as black streak in tear film Schirmer test (invasive) Assesses tear volume Thin strip of filter paper is bent into an L shape and inserted into lower fornix Wet length after a fixed time period (5 minutes) is measured Short wet length means a possible dry eye Test is subject to many artifacts Cheap and readily available Interpreting the results (Natahan et al 2024): - 0-5mm extremely dry eyes - 5-10mm : moderately dry eyes - 10-15mm: possible dry eyes - >15mm: normal tear function Phenol-Red Thread Test (invasive) Also to assess tear volume Works using the same principal as the Schirmer test When wet the thread turns red Measure the length of the wet thread after 15 secs  More comfortable than Schirmer test  Rose Bengal staining (invasive) Decreased lacrimation produces cell degeneration. Rose Bengal stains the resulting necrotic cells Look at amount of staining to determine how much cell degeneration has occurred and hence evaluate dry eye  Lissamine Green (invasive) Stains dead or degenerated cells and mucus Strip wet with saline (drops kept on strip for 5 secs min) Instilled on inferior cul-de-sac View with white light after 1-4 mins Use Hoya 25A filter or Kodak wratten 92 filter Not widely available Questions?