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Biomedical subjects

S M Haworth

Publications and source records attributed to S M Haworth.

11 recordsLinked to original sources
PubMed2006

Modified virtual reality technology for treatment of amblyopia.

PURPOSE: The conventional patching/occlusion treatment for amblyopia sometimes gives disappointing results for a number of reasons: it is unpopular, prolonged, frequently resulting in poor or noncompliance, and also disrupts fusion. The aim of this research was to develop a novel virtual-reality (VR)-based display system that facilitates the treatment of amblyopia with both eyes stimulated simultaneously. METHODS: We have adopted a multidisciplinary approach, combining VR expertise with a team of ophthalmologists and orthoptists to develop the Interactive Binocular Treatment (I-BiT) system. This system incorporates adapted VR technology and specially written software providing interactive 2D and 3D games and videos to the patient via a stereo (binocular) display, and a control screen for the clinician. RESULTS: We developed a prototype research system designed for treatment of amblyopia in children. CONCLUSIONS: The result is a novel way to treat amblyopia, which allows binocular treatment. It is interactive, and as it is partially software based, can be adapted to suit the age/ability, and needs of the patient. This means that the treatment can be made captivating and enjoyable. Further research is on-going to determine the efficacy of this new modality in the treatment of amblyopia.

Amblyopia↗
PubMed2006

Preliminary results from the use of the novel Interactive binocular treatment (I-BiT) system, in the treatment of strabismic and anisometropic amblyopia.

BACKGROUND: We have developed a novel application of adapted virtual reality (VR) technology, for the binocular treatment of amblyopia. We describe the use of the system in six children. METHODS: Subjects consisted of three conventional treatment 'failures' and three conventional treatment 'refusers', with a mean age of 6.25 years (5.42-7.75 years). Treatment consisted of watching video clips and playing interactive games with specifically designed software to allow streamed binocular image presentation. RESULTS: Initial vision in the amblyopic eye ranged from 6/12 to 6/120 and post-treatment 6/7.5 to 6/24-1. Total treatment time was a mean of 4.4 h. Five out of six children have shown an improvement in their vision (average increase of 10 letters), including those who had previously failed to comply with conventional occlusion. CONCLUSIONS: Improvements in vision were demonstrable within a short period of time, in some children after 1 h of treatment. This system is an exciting and promising application of VR technology as a new treatment for amblyopia.

Amblyopia↗
PubMed1991

Disappearance of ocular malignant melanoma on computerised scan after spontaneous necrosis: clinical, radiological and pathological features.

An 82 year old patient was lost to follow-up having been diagnosed both clinically and on CT scan as having a right choroidal malignant melanoma. Twenty months later she presented with a painful right proptosis, dense cataract and raised intraocular pressure. A second CT scan showed orbital cellulitis with no evidence of the previous mass. Following enucleation histopathological examination revealed that the tumour had undergone total spontaneous necrosis. The implications of the CT scan findings are discussed. Five cases of necrosed choroidal malignant melanoma producing proptosis in the absence of extrascleral tumour extension have now been described.

Aged↗
PubMed1991

Determination of the nodal point position in the pseudophakic eye.

The optics of the schematic eye have been described by Gullstrand and Listing (System of Ophthalmology (ed. H. Kimpton), Vol. 5, C. V. Mosby, London (1970], data being averaged from a series of adult eyes with a crystalline lens. A ray of light from the height of any given object passing, undeviated, through the nodal point will determine the height of its image on the retina. The nodal point positions, therefore, are fundamental in determining image size, and any eye-to-eye variation in a patient will control the amount of aniseikonia. The optics of the pseudophakic eye are described together with a scientific method for determining the nodal point positions, and the implications are discussed.

Cornea↗
PubMed1991

Aniseikonia: a method of objective assessment in pseudophakia using geometric optics.

There have been various reports in the literature regarding the limits that separate acceptable from disturbing aniseikonia. A criterion value of 5% is often quoted but actual values in pseudophakia may vary from 2% to 10%, depending on the type and position of implant used. In the accompanying paper we have reported a method by which image size can be calculated in the pseudophakic eye. Using this method a series of patients with anterior and posterior chamber implants were analysed and the image size for both eyes of each patient determined. This was compared with the patient's subjective appreciation.

Aniseikonia↗
PubMed1990

Calculated versus A-scan result for axial length using different types of ultrasound probe tip.

The axial lengths of 30 pseudophakic eyes were determined by calculation using geometric optics and by A Scan ultrasound using focused fluid filled 'soft' and solid probes. The results from the same ultrasound machine using both types of probe were analysed for their correlation with the calculated axial lengths. The majority of the ultrasound results were shorter than their calculated values but those obtained with the fluid filled 'soft' probe (with consequently less corneal indentation and axial length shortening) were significantly more accurate than those from the solid probe (0.02 greater than p greater than 0.01).

Anthropometry↗
PubMed1990

Pseudophakic accommodation? A study of the stability of capsular bag supported, one piece, rigid tripod, or soft flexible implants.

A group of pseudophakic patients was investigated to determine whether their implants shift along an anteroposterior axis under different conditions of ciliary muscle stimulation. There was no statistically significant change in refraction after either pilocarpine or cyclopentolate administration. A change in anterior chamber depth between the position after pilocarpine and that after cyclopentolate was found. It appears that rigid posterior chamber implants do move backwards on ciliary muscle relaxation, but by a maximum 0.25 mm. This is not thought to represent a mechanical threat to ocular health. It is also not enough to account for the apparent accommodative ability of some pseudophakic patients. The possible causes for this phenomenon are discussed.

Accommodation, Ocular↗
PubMed1985

Follow-up of 439 Federov Mark I lenses implanted after ICCE, with rationale for change and comparative results at one year.

This paper presents the sight threatening complications at one year (439 eyes), four years (320 eyes) and seven years (106 eyes) following ICCE with Federov Mark I lens implantation, together with my rationale for change to the Choyce Mk IX following ICCE and the Pearce Equilimb lens following ECCE. The problems with the Federov Mark I lens relate: (i) to its design, needing a widely open section for insertion; (ii) iris support which provides mobile fixation with potential for macular oedema, retinal detachment, corneal touch and decompensation and eventual iris disintegration with lens dislocation. The complications at one year are then compared with those using 176 Choyce Mk IX and 113 Pearce Equilimb lenses.

Corneal Diseases↗
PubMed1982

After 426 Fyoderov lens implantations.

This is a review of 426 Fyoderov Mk I lenses inserted by one surgeon following intracapsular cataract extraction. Important complications in the first year are, macular oedema and retinal detachment with bullous keratopathy increasing over the years and frequently associated with previous problems. It is concluded that the ideal intraocular implant is a single plane lens, independent of iris support, without loops and suitable for insertion after extracapsular cataract extraction through a section in the plane of lens insertion.

Cataract Extraction↗