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Questions and Answers
Which of the following is NOT typically included in a pathology request form?
Which of the following is NOT typically included in a pathology request form?
When collecting a microbiology specimen, what specific information about the patient's current medications is essential to include on the request form?
When collecting a microbiology specimen, what specific information about the patient's current medications is essential to include on the request form?
In addition to clinical examination, what can medical laboratories provide, to aid in the diagnosis of ocular disease?
In addition to clinical examination, what can medical laboratories provide, to aid in the diagnosis of ocular disease?
Which of the following investigations is NOT typically carried out in a pathology laboratory?
Which of the following investigations is NOT typically carried out in a pathology laboratory?
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What additional information is specifically required on a request form when blood is being collected for drug level monitoring?
What additional information is specifically required on a request form when blood is being collected for drug level monitoring?
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For what type of ocular disease is a fasting blood sample particularly important to note on the request form?
For what type of ocular disease is a fasting blood sample particularly important to note on the request form?
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What is the primary reason for including clinical history and examination findings on the pathology request form?
What is the primary reason for including clinical history and examination findings on the pathology request form?
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What is the role of the reference values that are provided alongside laboratory test results?
What is the role of the reference values that are provided alongside laboratory test results?
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Why is the timing of specimen collection important, especially for blood samples?
Why is the timing of specimen collection important, especially for blood samples?
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What is the primary reason for repeating the surgical process when a lesion extends to the margin of a section?
What is the primary reason for repeating the surgical process when a lesion extends to the margin of a section?
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Which of the following is NOT a typical step in handling and transporting specimens?
Which of the following is NOT a typical step in handling and transporting specimens?
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Which of the following lid lesions is considered a premalignant condition?
Which of the following lid lesions is considered a premalignant condition?
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Why are blood samples for electrolyte studies not generally refrigerated if there is a delay?
Why are blood samples for electrolyte studies not generally refrigerated if there is a delay?
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Apart from basal cell carcinoma, which of the following malignant lid lesions is mentioned as less common?
Apart from basal cell carcinoma, which of the following malignant lid lesions is mentioned as less common?
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What is the primary purpose of fixing tissue specimens in 10% formalin prior to light microscopy?
What is the primary purpose of fixing tissue specimens in 10% formalin prior to light microscopy?
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What is a key feature of Moh’s micrographic surgery that distinguishes it from frozen section?
What is a key feature of Moh’s micrographic surgery that distinguishes it from frozen section?
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Which of these specimens are MOST likely to be transported fresh without fixation?
Which of these specimens are MOST likely to be transported fresh without fixation?
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Which of these scenarios require a biopsy?
Which of these scenarios require a biopsy?
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What is the main purpose of a frozen section in surgical procedures?
What is the main purpose of a frozen section in surgical procedures?
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How should tissue specimens be prepared for electron microscopy (EM)?
How should tissue specimens be prepared for electron microscopy (EM)?
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What is the immediate next step after a specimen is excised during surgery for a frozen section?
What is the immediate next step after a specimen is excised during surgery for a frozen section?
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Why is it important to consult with the pathology laboratory if there is uncertainty about specimen handling?
Why is it important to consult with the pathology laboratory if there is uncertainty about specimen handling?
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What is the most common treatment method for persistent or symptomatic chalazia?
What is the most common treatment method for persistent or symptomatic chalazia?
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What is the purpose of an incisional biopsy compared to an excisional biopsy?
What is the purpose of an incisional biopsy compared to an excisional biopsy?
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Which thyroid function test is affected by changes in serum binding proteins?
Which thyroid function test is affected by changes in serum binding proteins?
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Which of the following tests directly measures the amount of unbound thyroxine in the bloodstream?
Which of the following tests directly measures the amount of unbound thyroxine in the bloodstream?
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What is a key clinical feature, consistent with thyroid dysfunction, but may be difficult to recognize?
What is a key clinical feature, consistent with thyroid dysfunction, but may be difficult to recognize?
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What is the primary diagnostic objective when using Thyroid-stimulating hormone receptor antibody testing?
What is the primary diagnostic objective when using Thyroid-stimulating hormone receptor antibody testing?
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Which blood test is used as a non-specific marker of inflammation in cases of Giant Cell Arteritis?
Which blood test is used as a non-specific marker of inflammation in cases of Giant Cell Arteritis?
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Which of the following is a specific symptom associated with Giant Cell Arteritis?
Which of the following is a specific symptom associated with Giant Cell Arteritis?
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In hypothyroidism, which of the following changes in test results is most likely?
In hypothyroidism, which of the following changes in test results is most likely?
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If a patient has hyperthyroidism, what would be the expected change in Free T4 level?
If a patient has hyperthyroidism, what would be the expected change in Free T4 level?
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What is the primary measurement used to determine the Erythrocyte Sedimentation Rate (ESR)?
What is the primary measurement used to determine the Erythrocyte Sedimentation Rate (ESR)?
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For a 60-year-old woman, what would be considered the maximum normal ESR?
For a 60-year-old woman, what would be considered the maximum normal ESR?
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Which condition is NOT typically associated with an elevated ESR?
Which condition is NOT typically associated with an elevated ESR?
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In the context of thyroid function, when is T3 level measurement most appropriate?
In the context of thyroid function, when is T3 level measurement most appropriate?
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What is the most sensitive initial screening test for thyroid dysfunction in ambulatory patients?
What is the most sensitive initial screening test for thyroid dysfunction in ambulatory patients?
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According to the content, what effect does inflammation have on red blood cells in relation to ESR?
According to the content, what effect does inflammation have on red blood cells in relation to ESR?
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Why is C-reactive protein (CRP) considered more useful than ESR in some instances?
Why is C-reactive protein (CRP) considered more useful than ESR in some instances?
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What is the typical normal range for haemoglobin in a female, as shown in the reference values?
What is the typical normal range for haemoglobin in a female, as shown in the reference values?
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What does the measurement of antithyroid antibodies primarily indicate?
What does the measurement of antithyroid antibodies primarily indicate?
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If a patient has a red blood cell count of 5.8 x 10^12 /L, and is female, is this value within the normal range?
If a patient has a red blood cell count of 5.8 x 10^12 /L, and is female, is this value within the normal range?
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Which of the following is NOT typically measured in a full blood count?
Which of the following is NOT typically measured in a full blood count?
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Which of the following conditions will show elevated antimicrosomal antibodies?
Which of the following conditions will show elevated antimicrosomal antibodies?
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If a patient has presumed thyroid disease, but their thyroid function tests are within normal limits, how often does this occur?
If a patient has presumed thyroid disease, but their thyroid function tests are within normal limits, how often does this occur?
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If a patient has a haemoglobin level of 13 g/dL, and a haematocrit of 42%, which of these statements is correct?
If a patient has a haemoglobin level of 13 g/dL, and a haematocrit of 42%, which of these statements is correct?
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What is the normal range for white blood cells (WBC) according to the provided table?
What is the normal range for white blood cells (WBC) according to the provided table?
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What is measured by 'Mean cell haemoglobin concentration' (MCHC) within a full blood count?
What is measured by 'Mean cell haemoglobin concentration' (MCHC) within a full blood count?
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Study Notes
MSc in Clinical Optometry: Principles of Therapeutics - Laboratory Investigation in Ocular Disease
- This unit reviews common laboratory investigations in ocular disease, outlining specimen collection, processing, and interpretation methods.
- Eight hours of study.
- Learning outcomes include identifying common laboratory tests for ocular diseases and understanding their indications and results.
Introduction
- Ocular and systemic diseases are initially assessed via thorough medical history and clinical examination.
- Laboratory tests help determine disease stage, severity, and aid in differential diagnosis.
- Laboratory investigations are categorised as anatomical pathology, haematology, chemical pathology, immunopathology, genetics, microbiology, and special tests.
- Specimen collection, transportation, and analysis are critical. Pathology request forms must include patient details, history, examination findings, and medications.
- Timing of specimen collection is important (e.g., blood for drug level monitoring should be taken before the next dose).
- Results often come with normative data or reference values.
Specimen Handling and Transport
- Specimens are placed in sterile containers, labeled immediately.
- Care is taken to prevent contamination of the specimen and the safety of staff handling it.
- Specimens are transported promptly to the laboratory and handled carefully according to each specific test requirements (e.g., tissue for EM might need rapid fixation).
Tissue Specimens
- Fresh specimens are useful for frozen sections, Mohs micrographic surgery, and flow cytometry.
- 10% formalin is common for light microscopy.
- Frozen sections are used for complete excision margin control, especially for malignant lesions, with adequate margins.
- Mohs micrographic surgery is specifically recommended for canthal cancers, focusing on rigorous margin control.
- Histological examinations are often required, particularly for surgical decisions related to margins of excision.
Investigation of Ocular Disease: Eylids and Orbit
- Investigations can be via biopsy, cytology, ophthalmic radiology, or ophthalmic ultrasonography.
- Benign lid tumours, including papillomas, seborrhoeic keratosis, keratoacanthoma, naevi, and vascular lesions, are possible.
- Premalignant tumours are actinic keratosis. The most common malignant eyelid lesion is basal cell carcinoma, followed by rarer squamous cell and sebaceous gland carcinomas.
- Chalazia are common and often resolve spontaneously, but persistent or symptomatic ones may need surgical treatment, requiring biopsy for accurate diagnosis.
- Incisional and excisional biopsies differ in how much of the lesion is removed.
- Electron microscopy may be necessary for undifferentiated tumours.
- Immunohistochemical investigations may be performed with tissue collected by biopsy fixed in formalin.
Investigation of Orbital and Pre-septal Cellulitis
- Pre-septal cellulitis and orbital cellulitis are significant ocular infections.
- CT imaging is crucial for differentiation based on tissue location front or behind the septum orbitale.
- Investigation for orbital cellulitis often includes body temperature, full blood count, blood culture, and connective tissue (CT) scan of the orbit, sinuses, and brain.
Full Blood Count
- The full blood count (FBC) includes red blood cell (RBC) count, haematocrit, haemoglobin, mean cell haemoglobin concentration, mean cell haemoglobin, white blood cell (WBC) count with differential, and platelet count, using automated analysers.
- Specific reference ranges for male and female are cited in the table.
Investigation of Thyroid Disease
- Chemical pathology, including hormone tests, is frequently used to assess thyroid function.
- Total T4/T3, thyroid hormone binding ratio (THBR), and thyroid-stimulating hormone (TSH) are measured.
- Free T4/T3 can be calculated using THBR.
- T3 levels are used in conjunction with normal T4 levels, if there's a clinical suspicion of hyperthyroidism.
Investigation of Giant Cell (Temporal) Arteritis
- Giant cell arteritis (GCA) is inflammation of blood vessels supplying the head.
- Erythrocyte Sedimentation Rate (ESR) and C-Reactive protein (CRP) are non-specific inflammatory markers, with elevated values suggesting active disease.
Investigation of Microbial Keratitis
- Microbial keratitis is chiefly bacterial, often caused by contact lens wear.
- Investigating include anatomical pathology (biopsy) and microbiology (cultures e.g. Gram stain, culture).
Investigation of Herpes Simplex Keratitis
- Diagnosis is often clinical, but viral culture could be used for confirmation if unsure.
Investigation of Lacrimal Disorders
- Tears can be collected via micropipettes or Schirmer strips for biochemical analysis (osmolality, lactoferrin, lysozyme).
- Hyperosmolality is a sensitive, but not specific, marker for keratoconjunctivitis sicca (KCS).
Investigation of Conjunctival Disease
- Anatomical pathology (biopsy) is the gold standard for conjunctiva disease diagnosis; it is performed when other tests are inconclusive.
Investigation of Uveitis
- Uveitis is inflammation of the middle eye layer; anterior uveitis is generally non-systemic and resolves with treatment.
- Posterior uveitis, panuveitis, or intermediate uveitis might warrant investigations for potential systemic causes.
- Diagnosing and assessing different forms of uveitis (anterior, intermediate, posterior, and panuveitis) is dependent on the clinical symptoms but is often assisted by blood studies.
- Investigations focus on identifying systemic disease factors when uveitis remains non-responsive to treatment for prolonged periods.
Investigation of Scleritis
- Scleritis is a chronic, inflammatory sclera disease; in over 50% of cases, an associated systemic illness could be diagnosed.
- Laboratory tests (e.g., blood counts, ESR, RF, ANCA, CRP, ACE, uric acid) may be used to find potential associated systemic diseases.
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Description
This quiz assesses your understanding of common laboratory investigations in ocular diseases, including specimen collection, processing, and interpretation methods. You will explore the importance of laboratory tests in determining disease severity and aiding in differential diagnosis. Prepare to identify key tests and their indications as part of your learning outcomes.
