1.1 Anterior Segment Examination
Attention should be given to the wording of the question which often directs the candidate where to look:
“Examine the”…
- External Eye – Periorbital tissue, eyelid, margins, conjunctiva, fornices, limbus and corneal surface
- Anterior Segment – Eyelids, conjunctiva, cornea (all layers), anterior chamber, iris and lens
Always stand back and examine the patient as a whole. Age / gender / ethnicity are often useful in narrowing the potential differential diagnoses. Iris heterochromia, symblephara, ankyloblepharon and forniceal shortening are often more obvious on gross inspection before beginning the slit lamp examination.
- Blepharitis,
- Ectropion / entropion / punctum
- Madarosis / hypertrichiasis
- Scarring from HZO / pigment changes
- Ask the patient to ‘Look up’ (while pulling the lower lid down): Symblepharon / ankyloblepharon / forniceal shortening
- Ask the patient to ‘Look down’ (while pulling the upper lid up): Trabeculectomy bleb / glaucoma drainage device
- Scleral buckle
- Offer to evert the upper lid
- Always mark the visual axis.
- Always draw a cross-section with corneal epithelium / stroma / endothelium, iris and lens (Figure 1.1.1). It is important to document the level, size, shape and location of any corneal lesion.
Note:
- Shape: e.g. Keratoconus
- Size: Measure the corneal diameter with a handheld ruler if suspicious of congenital glaucoma. Greater than 12mm in an adult is abnormal, Microcornea is defined as corneal diameter <10mm
- Thinning: Estimate and document the remaining thickness as a % of normal
- Scars, wounds
- Corneal graft
i. Type (penetrating vs. anterior lamellar vs. endothelial)? Size? Clarity?
ii. Sutures? (interrupted, continuous, broken / loose?)
iii. Pay special attention to the graft-host junction
iv. Neovascularisation?
v. Look at the other eye for clues as to why the patient had a graft - ± Tear film / marginal tear strip
In addition, look at each corneal layer:
- Epithelium: Epithelial defects, punctate epithelial erosions, superficial punctate keratitis, dystrophies, microcystic oedema, Fleischer ring, limbal stem cell failure (conjunctivalisation of the cornea)
- Stroma: Dystrophies, stromal oedema, vessels (superficial or deep?), prominent corneal nerves
- Endothelium: Guttata, pigment dispersion, keratic precipitates (KP), Descemet’s membrane folds
The presence of one sign (e.g. a conical cornea) should prompt you to look for other associated signs of that condition (e.g. Down syndrome, vernal kerato-conjunctivitis, Fleischer ring- best seen with cobalt blue light, prominent corneal nerves, hydrops / corneal scarring and Vogt striae of keratoconus).
If an ocular surface mass is present (e.g. Ocular surface squamous neoplasia), you must exclude orbital invasion. Check for:
- Lymphadenopathy
- Corneal sensation
- Ophthalmoplegia
- Intraocular examination including gonioscopy for angle involvement
- Cells / flare
- Hypopyon, hyphaema
- Anterior chamber depth (narrow angle?). Von Herrick’s test can estimate angle depth
If an intraocular mass is present (e.g. iris melanoma), then check for:
- Hyphaema
- Nodular vs diffuse configuration
- Ectropion uveae – seen in iris melanoma
- Refractory glaucoma - raised IOP
- Gonioscopy for angle involvement
- Transillumination – more likely to be a cyst
- Subjacent ciliary body involvement – will need eye to be dilated
- Dilated fundus examination for extension posteriorly
- Round (trauma, posterior synechiae, vermiform movements)
- Ectropion uveae (may be suggestive of prior rubeosis iridis)
- Pseudoexfoliation (PXF)
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Vitreoretinal Surgery Online
This open-source textbook provides step-by-step instructions for the full spectrum of vitreoretinal surgical procedures. An international collaboration from over 90 authors worldwide, this text is rich in high quality videos and illustrations.
