1. Summary of programme area and objectives

1.1 Neuro-ophthalmologists devote much of their time to the eye manifestations of neurological disorders, including stroke, migraine, multiple sclerosis, cerebral tumours and head injury. Intensive investigations into the aetiology and pathogenesis of these disorders continues and this will inevitably impact on the prevalence of untreatable neural blindness.

1.2 As neuro-ophthalmology is a very wide spectrum of disease the focus of this programme is on clinical psychophysical and electrophysiological tests to assess afferent visual function.

1.3 The combination of imaging and functional studies in the living human eye allows us to further our understanding of the underlying causes of visual loss and the effects of interventions. New methods of detecting loss of visual field and acuity have been developed. These rely on quantitative analysis techniques combined with presentation of complex data to allow earlier detection of visual field loss.

  2. Programme plan

2.1 Several novel methods of imaging have made visible elements of the living human eye which until recently have only been seen in post mortem eyes. We have modified a prototype confocal Laser Scanning Ophthalmoscope to provide high magnification images of the photoreceptor mosaic in the living human eye.

2.2 The sponge-like structure of the lamina cribrosa through which all the nerve fibres leave the eye to reach the brain can be seen with sufficient quality to provide quantitative image analysis.

2.3 Autofluorescence imaging of the retinal pigment epithelium arising from the age pigment, lipofuscin, reveals its distribution in the normal eye and ocular abnormalities.

2.4 Approximately ten times improved depth resolution has been achieved with the new prototype Ocular Coherence Tomography-based imaging device. This high resolution instrument provides images at different depths within the retina which approaches some of the structural details normally seen only with the microscope.

2.5 Psychophysical investigations have shown characteristic changes in visual function associated with the structural changes revealed in the imaging studies. The depth plane of best visual acuity was found to correspond to the depth plane of the cone photoreceptor mosaic. Abnormal elongation of the pores of the lamina cribrosa is associated with visual loss in the corresponding part of the visual field. Quantitative autofluorescence imaging reveals a relation between abnormal levels and rod and cone photoreceptor dysfunction.

2.6 The manner in which different abnormalities of vision affect specific aspects of visual function are being investigated. For example conventional visual acuity tests may reveal little loss of function despite severe degradation of vision. This leads to the need for new tests of visual function which can more completely describe function.

2.7 Specific abnormalities of magnocellular and parvocellular function in glaucoma are being studied to further our understanding of these processes. The use of motion detection perimetry has revealed abnormalities of visual function which precede conventional perimetric losses.

2.8 Perimetry remains the most reliable clinical means of localising lesions in the visual pathways. Unfortunately the sophisticated techniques in use remain subjective and time-consuming and not tolerated by a significant portion of patients. Efforts to develop accurate rapid objective mapping and quantification of sensitivities throughout the field of vision continue, most likely through the modification of the visual evoked response test. These results could be correlated with psychophysical and pupil perimetry abnormalities to further refine and rationalise the present array of tests in use.

2.9 In contrast to subjective psychophysical techniques, confocal scanning laser ophthalmoscopy, optical coherence tomography and retinal thickness analysis are all evolving objective techniques, which are likely to prove to be of direct relevance to the assessment and treatment of patients with acquired optic neuropathies.

  3. Future development work in the programme during 2002/3

Research Priorities

3.1 Epidemiological and Service Issues

· Investigations of visual function using psychophysical methods.
· Visual rehabilitation in untreatable neural blindness.

3.2 Clinical and Laboratory Issues

· The development of novel techniques for imaging the eye
· Protection of vision in chronic raised intracranial pressure syndromes.
· Rehabilitation of binocular function in neurogenic squint.
· Immunotherapies for inflammatory optic neuropathies.