Ophthalmology
Question 22 of 97
A 32 year old woman presents to the Emergency Department with a 3 day history of left eye pain and excessive lacrimation. Your findings on fluorescein staining are shown. What is the most likely diagnosis?
Answer:
There is a dendritic ulcer in keeping with herpes simplex keratitis.Infective Keratitis
Ophthalmology
Last Updated: 10th January 2023
Bacteria, fungi, protozoa, and viruses can penetrate the body's defence mechanisms and invade the cornea. A key underlying predisposing factor for bacterial, fungal, Acanthamoeba, and viral keratitis is a compromised corneal epithelium.
Risk Factors
- Corneal trauma
- Contact lens wear
- Corneal abrasion/erosion
- Corneal exposure from poor lid function
- Foreign body (particularly vegetable matter)
- Previous eye surgery
- Severe dry eyes
- Trichiasis
- Hereditary corneal dystrophies
- Blepharitis and conjunctivitis
- Immunosuppression
Causes
- Bacteria
- Pseudomonas aeruginosa
- Staphylococcus aureus
- Staphylococcus epidermidis
- Streptococcus pneumoniae
- Haemophilus influenzae
- Moraxella catarrhalis
- Viruses
- Herpes simplex
- Varicella/Herpes zoster
- Fungi
- Aspergillus and Fusarium species
- Candida albicans
- Protozoa
- Acanthamoeba species
Clinical Features
- Symptoms
- Eye pain
- Redness
- Photophobia
- Lacrimation
- Discharge
- Lid oedema
- Reduced visual acuity
- Signs
- Corneal infiltrate (presence of pathogens and inflammatory cells in the corneal stroma causes oedema and opacification of the normally transparent cornea)
- Corneal ulcer (a corneal infiltrate with an overlying epithelial defect is termed a corneal ulcer)
- Corneal vesicles (may be seen in herpetic keratitis)
- Dendritic ulcer (in HSV epithelial keratitis)
- This classic herpetic lesion consists of a linear branching corneal ulcer
Management
- Refer urgently to ophthalmology
- Corneal scrapings should be sent for cultures and sensitivity prior to initiating treatment
- General management
- Contact lens use should be discontinued while the eye is inflamed
- Oral analgesics and other pain medicine should be given as needed
- A topical cycloplegic (pupil-dilating agent) should be used in the presence of an anterior chamber reaction and photophobia
- An eye shield should be placed over eyes when considerable corneal thinning is present
- Bacterial infection
- Unless specific historical or clinical evidence suggests otherwise, microbial keratitis should be assumed to be bacterial; empiric treatment consists of topical antibacterials
- Topical corticosteroids should usually be added as soon as the epithelial defect closes and the infiltrate appears to be responding well to the antibiotic treatment.
- Even in non-bacterial infectious keratitis, epithelial defects should prompt the use of broad-spectrum topical antibacterials for prophylaxis
- Herpetic infection
- Topical antiviral drug treatment for epithelial keratitis
- Oral antiviral and topical corticosteroid drug treatment for stromal keratitis
Complications
- Corneal perforation
- Endophthalmitis
- Corneal scarring
- Cataract
- Glaucoma
- Secondary infection
- Permanent visual impairment
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
