Fundoscopy
Fundoscopy involves using an ophthalmoscope to view the fundus of the eye, which consists of the retina, optic disc, macula, and fovea. In some cases, mydriatic agents (e.g. tropicamide) are given to dilate the pupil and improve the view of the fundus.
Slit-lamp examination
A slit-lamp examination involves shining a high-intensity ‘slit’ of light into the eye and is used to view the anterior segment of the eye. The posterior segment (fundus) can be seen using an additional hand-held lens.
Stains may also be given to aid the examination. An example is fluorescein which glows green-blue under cobalt blue light. This may help with identifying ulcers in keratitis.
Gonioscopy
Another lens (goniolens) can be used alongside a slit-lamp examination to perform gonioscopy, which assesses the angle of the eye. Gonioscopy is essential for the diagnosis of acute angle-closure glaucoma.
Fluorescein angiography
Fluorescein angiography assesses the circulation of the retina and choroid (a vascular layer between the retina and sclera). Fluorescein dye is injected intravenously and retinal photographs are taken which can show neovascularisation and leakage.
Optical coherence tomography
Optical coherence tomography (OCT) uses light to take cross-section images of the retina which can identify glaucoma, macular problems and oedema, and optic nerve damage/inflammation.
Ocular tonometry
A tonometer makes contact with the eye and measures the intraocular pressure (IOP) which is around 10-21 mmHg. Goldmann tonometry is the gold-standard which involves using a prism pressed against the cornea. Non-contact (‘puff of air’) tonometers may also be used, but they are not as accurate.
Visual field testing
Visual field testing may be done via a confrontational visual field test. This involves sitting opposite the patient, covering one eye, and moving a finger in different regions of the visual field to look for abnormalities. It works on the assumption that the examiner’s visual field is intact.
Perimetry
Perimetry is another form of visual field testing that involves flashing a light at different points in the visual field and the patient pushing a button if they see the flashing light.
Amsler grid
This is used to assess a patient’s central visual field, more specifically the macula. In age-related macular degeneration (AMD), patients may notice distortion of the lines (metamorphopsia).
