No description available.

A large negative spike potential, which is closely related to the onset of saccadic eyemovements, can be recorded from electrodes adjacent to the orbits. This potential, thepresaccadic spike potential, has often been regarded as an artefact related to eyemovement recordings and little work has been performed to establish its normal waveformand parameters. A positive spike potential, exactly coincident with the frontal negativespike, has also been recorded from electrodes positioned over the posterior scalp andthere has been some debate regarding any possible relationship between the twopotentials. The frontal spike potential has been associated with motor unit activity in theextraocular muscles prior to the saccade. This thesis investigates both the large anteriorand smaller posterior spike potentials and relates these recordings to the saccadic eyemovements associated with them. The anterior spike potential has been recorded from normal subjects to ascertain its normallatency and amplitude parameters for both horizontal and vertical saccades. A relationshipbetween saccade size and spike potential amplitude is described, the spike potentialamplitude reducing with smaller saccades. The potential amplitude also reduces withadvancing age. Studying the topographical distribution of the spike potential across thescalp shows the posterior spike activity may arise from potential spread of the larger frontalspike potential. Spike potential recordings from subjects with anomalous eye movements further implicate the extraocular muscles and their innervation in the generation of the spike potential. These recordings indicate that the spike potential may have some use as a clinical recording from patients with disease conditions affecting either their extraocular muscles or the innervational pathways to these muscles. Further recordings of the potential are necessary, however, to determine the exact nature of the changes which may occur with such conditions.

No description available.

No description available.

Studies suggest that natural autoantibodies may be part of an immunological network which maintains the normal homeostatic response seen in controls. Any defect in this network leading to autoimmunity may be represented in the anti-retinal antibody response observed in patients. Characterisation of the humoral autoimmune response occurring during active uveitis may provide valuable information on the immune mechanisms, both humoral and cellular, involved in uveitis. Serum titres and ELISA based tests can only partially describe an antibody response, a more complete description requires access to the B-cell repertoire constituting the response. In the past hybridoma technology has generated a wealth of vital information on antibody responses in animals, but with limited success when applied to humans, producing unstable cell lines with poor antigen affinity. Using scFv phage display antibody technology we attempted to isolate the immune response occurring during active uveitis using a phage display library derived from peripheral blood lymphocyte mRNA of a patient with active uveitis. In this study, we report the isolation and characterisation of human autoimmune recombinant scFv's from two libraries, a uveitis patient derived library and a healthy non uveitis donor derived library. Anti-IRBP and S-Antigen autoantibodies were successfully selected from both libraries. Sequence analysis of these selected autoantibodies revealed possible differential epitope targeting of disease associated anti-S-Ag autoantibodies, and exclusive use of the VH segment, DP49 was revealed among selected anti-S-Ag scFv's. In addition ELISA studies using the selected scFv's, and both patient and control serum, indicated that it may be possible to distinguish the 'natural' and disease associated anti-S-Ag responses at the idiotype/anti-idiotype network level.

M.Tech.

Purpose The purpose of this research was to evaluate the outcomes, specifically diplopia and enophthalmos, as well as the complications of surgical repair of orbital fractures using the transconjunctival surgical approach. Methods A cross-sectional descriptive study was conducted. Thirty patients who underwent surgical repair of an orbital fracture were included in this case series. All patients were operated using the transconjunctival surgical approach and in all cases the fracture was repaired with 0.4 mm nylon foil sheeting (Supramid). The preoperative and postoperative clinical findings of visual acuity, diplopia and enophthalmos were analyzed, and postoperative complications were noted. Results Twenty-five of 30 patients (83%) presented with diplopia preoperatively and two patients (7%) had persistent diplopia postoperatively. Enophthalmos of greater than 2mm was present in 16 of 30 patients (53%) preoperatively and five patients (17%) had persistent enophthalmos postoperatively. All patients with persistent postoperative diplopia and or enophthalmos underwent late surgical repair (mean 10.6 months). Ten patients (33%) in this series were repaired early, within three weeks of trauma, and had no diplopia or enophthalmos postoperatively. There were no cases of lower lid retraction or ectropion. There was one complication related to the nylon foil. Conclusion The transconjunctival surgical approach used to repair orbital fractures was associated with good functional outcomes and few complications. Early surgical repair of orbital blowout fractures and the use of nylon foil sheeting are supported by this case series.

A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Medicine in the branch of Ophthalmology Date: 22 June 2017 / Purpose: The purpose of this study was to explore the quality of life of patients who underwent an eye amputation after open globe injury. The study addressed both general and vision related quality of life, focussing on anxiety and depression. The demographics of the study participants/respondents were compared to similar studies. Design and Method: The study design was a quantitative, prospective cross- sectional study using as a data tool, a self-administered questionnaire with demographic information, an extract of the WHO PBD VF20 questionnaire and the EQ5D. The participants were sampled using the convenience sampling method from the oculo-prosthesis clinic at the St John Eye Hospital, Chris Hani Baragwanath Academic Hospital, Johannesburg, Gauteng, during March 2016 to June 2016. The information was collated and the data analysed using SAS to determine means, distributions and comparisons among the groups. Results: The demographics were comparable to other studies, except that more females were recruited in this current study. Vision specific quality of life: 51% of the respondents experienced no problems, 26.4% experienced problems, sometimes, and 9.3% experienced problems, very often. General health quality of life: 52,3% experienced an ideal life state. Only three respondents experienced a quality of life that was less than 50% of the ideal health state, all of whom indicated that they suffered severe pain. 83,8% of the study participants/respondents experienced a quality of life that was more than 75% of the ideal health state. Conclusion: Primary evisceration in severe ocular trauma is justified at the St John Eye Hospital due to the high burden of disease on the public health system (>70% of households), provided that certain criteria are met with regards to the visual potential of the eye. The higher female incidence could be due to alcohol misuse and gender violence; however, this will require further research. Despite the majority of the respondents having a health score of more than 75%, those with a higher pain score recorded a lower quality of life score. The participants who sustained open eye injuries leading to amputation were more prone to high levels of anxiety and depression. Continued health surveillance at the oculo-prosthesis clinic is advised with appropriate referrals to a social worker and or a psychologist/ psychiatrist and further on- referrals. / MT2017

PhD, Faculty of Health Sciences, University of the Witwatersrand, 2009

Thesis (Ed.D.)--Boston University.