Corneal Health Assessment Techniques

Lecture Recording

• The lecture is being recorded as part of Plymouth University's Content Capture Project
• The recording will be available via the Panopto block on the module DLE pages shortly
• Students can ask questions during the lecture
• If a student asks a question, it may appear on the recording
• The lecturer can pause the recording if a student does not want their question recorded

Optometry Skills Lecture

• The lecture is about Specialist Optometry Skills (OPT506)
• The specific topic is Slit Lamp Biomicroscopy 3
• The lecturer is Dr. Asma Zahidi
• A one-time code (XV-RL-YT) is provided

Lecture Outline

• The lecture will cover a revision of the anterior eye assessment using white light
• Tear film assessment will also be covered using white light
• Routine anterior eye assessment with blue light techniques will be discussed
• Recording findings will be the final portion of the lecture

Slit-Lamp Examination Flowchart (White Light)

• The examination starts with observing the lids, margins & eyelashes
• Next, the tears/tear film, conjunctiva and bulbar are examined.
• Palpebral and limbus areas are also considered
• Further areas include cornea, anterior chamber, iris, and crystalline lens

Slit Lamp Examination Flowchart (Blue Light)

• The blue light examination includes Tears/tear film, Cornea & Conjunctiva (bulbar & palpebral)
• The light is combined with NaFl

Blue Light Assessment

• Fluorescein strips are used
• The strips require saline solution for wetting
• Fluorescein is often used with topical anesthetic.

Fluorescein Installation

• The correct installation technique is illustrated
• Incorrect installation techniques are indicated with a red "X"

Invasive Tear Break-Up Time

• The slit lamp is set up with broad beam illumination
• A cobalt blue (Wratten 12) filter improves fluorescein visibility
• Sufficient magnification for the cornea is mandatory
• Students should ask the patient to blink a few times before the test
• The patient's eyes are kept open for as long as possible
• Tear break-up time is determined by observing the first break in the tear film which appears as a black streak

Tear Break-Up Time

• Various images of different types of tear break-up time are shown
• Severity of dry eye is classified as Severe, Mild/Moderate (using Area Break-up, Spot Break-up, Random Break-up and others)

Corneal Staining

• Dot-shaped defects on the corneal epithelium is a particular characteristic when staining is observed
• Visual inspection is possible by using Fluorescein and adding a yellow filter, which stains the tear film
• Symptoms that occur alongside corneal staining could include pain, redness of the eye and increased tear flow
• Paraellelepiped (16x) and Optic section (25x-40x) are used for assessment magnification

Corneal Staining - Aetiology

• Mechanical factors including trauma, foreign bodies, damaged lenses can be an aetiology
• Exposure, metabolic (hypoxia, hypercapnia) and solution-induced (SICS) are additional aetiologies
• Toxic factors like care regimen hypersensitivity and allergic factors (immediate/delayed) can also be a factor
• Infectious disease and general health issues can also result in corneal staining.

Corneal Staining - Pattern

• Dryness (Decompensated cells and Corneal staining)
• Mechanical cause (Removal of cells e.g. 3 and 9 o'clock staining)
• Toxic cause (Decompensated Cells, SICS)

Corneal Abrasions: Staining Patterns

• Various patterns of corneal abrasions are illustrated
• The patterns are categorized and described in detail.

Bulbar Conjunctival Staining

• Bulbar conjunctival staining is used as an indicator of dry eye
• Certain dry eye drops might result in higher mucin secretion and improved staining scores.
• Comparison of before and after staining is often conducted

Lid Eversion

• The patient is asked to look down to grasp the upper eyelid at the base of the lashes using one hand (H1)
• This is done at a 45-degree angle.
• The other hand (H2) is used to press the upper lid downwards (and a cotton bud can also be used).
• The lashes are pulled gently upwards, following the motion of the eye downwards.

Why Lid Eversion?

• Cobblestone-like nodules in the palpebral conjunctiva are a potential cause for lid eversion procedures
• Small deposits of calcium can often result as a consequence of the procedure

Record Keeping

• The recording methods used include grading scales
• The grading scales allow accurate recording of data and are used to monitor disease

Record Cards (Contact Lens)

• Grading scales are used for recording information regarding various eye conditions such as: conjunctival redness, limbal redness in both the right (R) and left (L) eyes.
• Various conditions are graded and included such as corneal neovascularisation, corneal staining, conjunctiva staining, papillary conjunctivitis, blepharitis and others.

Areas of the Superior Palpebral Conjunctiva

• Different zones (areas) in the superior palpebral conjunctiva for detailed analysis are covered
• Image references are provided as guide as well

Reasons for Using Grading Scales

• In health care, accurate recording is needed for physiological and pathological traits
• Monitoring disease
• Allows proper care follow-up by other clinicians
• Tracks investigative processes.
• Documents decisions made during the process

Difficulties in Descriptions

• Severity description can be subjective using terms like mild/moderate and severe
• Grading scales provide objectivity and standardization for assessing these factors

Grading Scales

• Types of grading scales can include photographic and drawn grading scales
• The photographic grading scale provides various visual references of grading factors.

Drawbacks of Grading Scales

• Photographic grading scales require extensive libraries for comparison.
• Different patients, perspectives and conditions might produce variable results.
• Photographic results are not always realistic

Grading

• Grading between units should be determined.
• A system for grading is needed

Grading (General Summary)

• Grading 0-normal, no tissue change
• Grading 1-trace, no clinical action required
• Grading 2-mild, clinical action may be required
• Grading 3-moderate, clinical reaction usually required
• Grading 4-severe, action urgently required
• Clinicians need further guidance to implement this grading system properly.

The Slit-Lamp Examination: Tips for Patient Comfort

• Communicate clearly to the patient before the examination
• Instrument-patient-examiner should be well aligned

Assessment of the Tear Film

• Methods of assessing tear film includes Non-invasive and invasive methods

Assessment of the Tear Film (Non-invasive)

• Non-invasive methods include Non-Invasive Tear Break-Up-Time (NIBUT), Tear Thinning Time, Tear Prism Height and Lipid Layer Evaluation

Assessment of the Tear Film (Invasive)

• Invasive methods include Tear Break-Up-Time (TBUT), Schirmer test, Phenol-red thread test, Rose Bengal staining and Lissamine Green

Tear Prism Height (Non-invasive)

• The tear prism height is a tear reservoir in the lower eyelid margin.
• The height is dependent on the tear volume.
• The tear prism height allows for indirect measurement of tear volume.

Tear Prism Height (Non-invasive)

• Measurements are in mm
• Graticule (if available) may be used
• Adjusting the slit lamp beam height
• Provides norms for tear prism height (0.2 to 1.0 mm)

Tear Break-Up Time

• Measures tear film stability, including time taken for break up after blinking
• Methods can be non-invasive or invasive
• Techniques involve observing specular reflection for assessing tear film commencement and end
• Different grid systems are used to evaluate the process

Sehrimer Test (Invasive)

• This test assesses tear volume by using a strip of filter paper, which is bent into an L shape and inserted into the lower fornix
• The length of the wet filter paper after 5 minutes is measured and is used to establish the presence of dry eyes

Phenol-Red Thread Test (Invasive)

• This innovative technique assesses tear volume utilizing the same principle as the Schirmer test.
• A thread is dipped/wet into the tear and if it turns red, it could indicate the possible presence of dry eye(s)
• Measurement of the red thread's wetness after 15 seconds will gauge the tear condition

Rose Bengal Staining (Invasive)

• Lacrimal production decreases, which, in turn, lowers cell degeneration.
• Rose Bengal will stain the necrotic cells.
• Staining amount is assessed to gauge the extent of cell degeneration and evaluate the eye condition

Lissamine Green (Invasive)

• This method is used to stain dead or deteriorated cells and mucus.
• A strip is wetted with saline, and after being placed on the inferior cul-de-sac, the view and inspection occur after 1-4 minutes using specific filter types, such as Hoya 25A or Kodak Wratten 92

Questions?

• A standard closing question for lectures.