Anterior Segment Eye OSCE Examination

1. Introduction
2. General Inspection
3. Eyelids and Lashes
4. Conjunctiva and Sclera
5. Cornea
6. Anterior Chamber
7. Iris and Pupils
8. Lens
9. Eyelid Eversion
10. Completing the Examination
11. Quiz

Wash your hands and don personal protective equipment if appropriate. This examination involves close contact with the patient's face and eyes, so good hand hygiene is essential to avoid transmitting infection between eyes or between patients.

Introduce yourself to the patient and ensure to mention your grade e.g. 3rd year medical student/junior doctor/consultant.

Confirm the patient's details taking 3 points of identification usually; full name, date of birth and NHS/hospital number.

Obtain consent for the examination, explaining what it will entail. Warn the patient that you may need to shine a bright light into their eyes, that this may be a little uncomfortable, and that you may need to gently touch their eyelids.

Ask about pain and any visual symptoms before you begin, and ask whether the patient wears glasses or contact lenses. Contact lens wear is an important risk factor for microbial keratitis.

Gather your equipment: a pen torch, a source of magnification (a slit lamp is ideal, but a direct ophthalmoscope set to around +10 dioptres, an Arclight ophthalmoscope or a magnifying loupe all work at the bedside), fluorescein drops and a cobalt blue light, topical anaesthetic drops if eversion is anticipated, and cotton buds. It is good practice to assess visual acuity with a Snellen chart first, as acuity is the single most important measure of visual function and provides essential context for any anterior segment findings.

Position the patient sitting comfortably, ideally on a chair at the slit lamp, or upright facing you with adequate lighting. Examine in a sequence and remember to assess both eyes for comparison, as many signs are only obvious when one eye is set against the other.

Begin by standing back and observing the patient and the area around them. Note whether they appear comfortable or distressed, and whether they are protecting the eye, holding it shut or shielding it from the light.

Look for photophobia (an aversion to light), which is a feature of anterior uveitis, keratitis and corneal abrasion, as light causes painful movement and spasm of the inflamed iris and ciliary body. Note any watering (epiphora) or discharge: watery discharge suggests a viral or allergic cause, whereas purulent (yellow-green) discharge suggests bacterial conjunctivitis.

Look around the bedside for clues such as an eye patch, contact lens cases or solution, bottles of eye drops, dark glasses (suggesting photophobia) or visual aids. Observe the patient's face as a whole for any obvious asymmetry, swelling or a vesicular rash. A rash in the distribution of the ophthalmic branch of the trigeminal nerve raises the possibility of herpes zoster ophthalmicus, particularly if it involves the tip of the nose (Hutchinson's sign), which indicates a high risk of ocular involvement.

Inspect the eyelids and lashes of both eyes, comparing the two sides. Assess the position, symmetry and any swelling of the lids. Generalised lid oedema may be inflammatory (as in periorbital or orbital cellulitis, which is a sight- and life-threatening emergency) or allergic, while a localised swelling is more likely to be a stye or chalazion.

Ptosis is a drooping of the upper eyelid. It may be caused by an oculomotor (third) nerve palsy, in which the eye is also typically 'down and out' with a dilated pupil, or by Horner's syndrome, where the ptosis is partial and accompanied by a constricted pupil (miosis) and reduced sweating (anhidrosis) due to interruption of the sympathetic supply. A fatigable ptosis that worsens through the day suggests myasthenia gravis.

Look at the direction the lid margin faces. In entropion the lid turns inwards, causing the lashes to rub on the cornea (trichiasis) and risking corneal abrasion. In ectropion the lid turns outwards, exposing the conjunctiva and causing watering and dryness.

Examine the lid margins for blepharitis, seen as crusting, redness and scaling at the base of the lashes due to chronic inflammation of the lid margin glands. A localised, tender, red swelling on the lid margin is a stye (hordeolum), an acute infection of a lash follicle, whereas a firmer, non-tender lump within the lid is usually a chalazion, a blocked and inflamed Meibomian gland. Note any lesions on the lid skin that could represent a basal cell carcinoma, particularly those with a pearly, ulcerated or lash-destroying appearance.

Ask the patient to look up while you gently pull down the lower lid to expose the inferior conjunctiva, then ask them to look in different directions to inspect the bulbar conjunctiva (overlying the white of the eye) and sclera.

Assess the pattern of any redness, as this is one of the most useful localising signs in the red eye. Diffuse redness that is more pronounced peripherally and spares the area around the cornea suggests conjunctivitis. A sectorial patch of redness involving one segment of the eye points to episcleritis; these superficial vessels can be moved with a cotton bud and blanch with topical phenylephrine, which helps distinguish it from deeper inflammation. Redness that is concentrated in a ring around the cornea (ciliary or circumcorneal injection) is more worrying and points to deeper pathology such as anterior uveitis, keratitis or acute angle-closure glaucoma.

A subconjunctival haemorrhage appears as a flat, well-demarcated area of bright red blood under the conjunctiva, with normal vision and no pain. It is caused by rupture of a small conjunctival vessel, often after coughing, straining or minor trauma, and is usually harmless and self-limiting, although it may prompt a check of blood pressure or clotting if recurrent.

Note any chemosis, a boggy, fluid-filled swelling of the conjunctiva that can balloon over the lid margin in marked cases. It reflects conjunctival oedema and is typically seen in allergic conjunctivitis, severe infection or orbital inflammation. While inspecting, also scan the conjunctival and scleral surfaces for any foreign body, abrasion or laceration, particularly after trauma; a full-thickness scleral laceration or a teardrop-shaped, peaked pupil should raise concern for a penetrating (open globe) injury, which requires the eye to be shielded and urgent ophthalmology referral without further manipulation.

Image - A subconjunctival haemorrhage seen as a flat, well-defined patch of bright red blood beneath the conjunctiva, sparing the cornea. Vision and the pupil are unaffected

Creative commons source by Daniel Flather [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]

Inspect the sclera itself for colour. A diffuse yellow tinge to the sclera indicates jaundice, reflecting a raised bilirubin. A localised area of deep, boring redness with severe pain that may wake the patient at night suggests scleritis, which is frequently associated with systemic autoimmune disease such as rheumatoid arthritis, whereas the milder, more superficial inflammation of episcleritis is usually self-limiting and far less painful.

Using your pen torch and magnification, inspect the cornea. A healthy cornea is perfectly transparent and gives a crisp, sharp reflection of the light. Loss of this clarity is significant.

A hazy or cloudy cornea suggests oedema, which occurs when the corneal endothelium fails to keep the cornea dehydrated. This is seen in acute angle-closure glaucoma (where the sharply raised intraocular pressure overwhelms the endothelial pump) and in advanced infection. Look for any white opacity or infiltrate on the cornea, which represents a collection of inflammatory cells and is the hallmark of a corneal ulcer or microbial keratitis, an ophthalmic emergency particularly in contact lens wearers.

Look for foreign bodies on the corneal surface, and assess the smoothness of the surface. A useful bedside test is to shine the torch tangentially across the cornea to throw any surface irregularity into relief.

At the slit lamp the same principle is used more powerfully: the illumination beam is narrowed to a thin slit and directed obliquely so that it cuts an optical section through the clear cornea. This reveals the corneal layers in three dimensions - the surface epithelium, the stroma and the deep endothelium - and lets you judge the exact depth of any ulcer, infiltrate or foreign body.

To detect epithelial defects that are invisible to the naked eye, instil fluorescein drops and examine the cornea under a cobalt blue light. Fluorescein pools in and binds to areas where the protective surface epithelium has been lost, so any defect lights up as a bright green patch. A diffuse or geographic area of uptake indicates a corneal abrasion, while a characteristic branching, dendritic pattern of staining is highly suggestive of herpes simplex keratitis - an important diagnosis to make, as inadvertent treatment with topical steroids can be sight-threatening.

Image - A small corneal ulcer in a contact lens wearer, highlighted by fluorescein staining. The defect in the corneal epithelium takes up the dye and fluoresces, marking the area of epithelial loss

Creative commons source by Iceclanl [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)]

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