Examination of the eyes
Examination of the eyes involves looking at the external aspect, such as the lids, lashes, sclera, conjunctiva and cornea for a healthy appearance.
- The lids should be symmetrical and move normally, up and down.
- The lashes should not turn inwards and scratch the eye.
- The sclera and conjunctiva should be white and not inflamed.
- The cornea should not be scratched or ulcerated (this will show up as a green stain with a 1% fluorescein dye).
- The anterior chamber should be clear.
- The pupils should be equal and react, and, with a normal lens, the pupil should appear black.
Ophthalmoscopy
An ophthalmoscope is a hand held instrument (with a condensing light source), which enables the examiner to look at the eye from the cornea, at the front, through the pupil, lens, and vitreous, to the retina at the back. In examining the retina, the condition of the retina itself, the blood vessel supply, the optic disc and the macula (the point of sharpest vision) can be seen. Many changes due to disease can be visualised, for instance, diabetes, high blood pressure (hypertension) macula degeneration, retinitis pigmentosa, tumour involving the eye, haemorrhage and detached retina.
Ideally, the ophthalmoscope is used in a darkened room, with the facility to dilate the pupils, if necessary. The retina may not be easily seen, if a cataract is present.
For detailed examination of the anterior segment and sometimes for the retina a Slit Lamp Microscope is used. This has a slit beam, which allows visualisation of these ‘clear’ tissues in ‘optical section.’
Tonometry
Tonometry measures the “eye pressure” or pressure of the aqueous humour in the anterior segment of the eye. This is important in the detection and treatment of glaucoma.
Usually at the Optician's an “Non-contact tonometer” (an air puff, which allows non – contact with the eye surface) is used, and all the patient feels is a puff of air on the white of the eye. Many patients dislike this.
Ultrasound
Ultrasound is non-invasive, and works by painlessly bouncing sound waves off the internal structure of the eye. This type of examination of the eye is useful when the retina cannot be easily visualised, for instance, if there is a cataract, or haemorrhage, blocking the visual access. Ultrasound is also used to demonstrate the presence and size of tumours and retinal detachment, where the view is poor, and also for measurement of the thickness of the cornea.
Eye care professionals
Optometrist: a health professional trained to detect and correct refractive errors, to examine and detect/diagnose eye conditions, to manage and prescribe treatment for various common eye problems.
Dispensing Optician: is trained to dispense spectacles and has expertise in ophthalmic lenses.
Ophthalmologist: a medical doctor trained in the examination, diagnosis, management and treatment (including surgery) of most ocular conditions.
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