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Biomedical subjects

E G Woodward

Publications and source records attributed to E G Woodward.

At least 19 recordsLinked to original sources
PubMed1998

The effect of age on the light scattering characteristics of the eye.

The rising mean age of our population has increased the need for understanding the physiologic consequences of ageing on visual function. Changes due to age were evaluated using a new scatter test implemented on the P_SCAN 100 pupillometer apparatus (Barbur, 1991). The test yields the full scatter function of the eye and also permits simultaneous measurement of pupil size (Barbur et al., 1995). In addition, contrast sensitivity was measured using sine wave gratings. The 28 subjects had a spherical refractive error between +0.50 DS and -0.25 DS, and astigmatism of less than -0.50 DC, V.A. of at least 6/6, and were ophthalmologically normal. To facilitate statistical analysis, subjects were classified into five groups according to age. For younger subjects (under 45 years), k', the integrated straylight parameter, varied little with age. For this group, k' ranged from 4.9 to 8.1. For subjects aged over 45 years, k' increased with age, ranging from 10.7 to 19.7. One way analysis of variance showed Group 5 (60 year olds) to have significantly greater k' than 20, 30, 40 and 50 year olds (P = 0.000). A slight downward shift in the contrast sensitivity function was seen over the age of 45. Significant differences between older and younger subjects were found at spatial frequencies of 3, and 10 cpd (P = 0.081, P = 0.002, respectively). Pupil diameter was found to reduce with age, but there was no significant difference between groups. Therefore, above 45 years, the ageing eye reveals a more rapid increase in forward scatter, and a reduction in contrast sensitivity, despite apparently good visual acuity.

Adolescent↗
PubMed1997

Use of contact lenses by firefighters: Part 2. Clinical evaluation.

Contact lenses can be worn in a variety of environmental conditions and do not increase the wearers risk of injury. In many situations they offer significant corneal protection. Currently firefighters are prohibited from using contact lenses. To evaluate whether contact lenses are a safe form of visual correction 50 firefighters were fitted, and examined after 1, 4 and 10 months of contact lens wear. Twenty-nine were fitted with soft contact lenses, and 21 with rigid gas permeable contact lenses. Statistically significant increase in lid sulcus hyperaemia was found in both the SCL and RGPCL groups (P < 0.01, P = 0.02, respectively), as well as an increase in hyperaemia of the vertical quadrant of the bulbar conjunctivae (P = 0.01, P = 0.02, respectively). In addition the RGPCL group showed a statistically significant increase in hyperaemia of the lateral portion of the bulbar conjunctivae (P < 0.01), consistent with exposure epitheliopathy. The SCL group showed statistically significant increase in corneal staining in the vertical quadrant for all visits (P = 0.02, P = 0.01, P = 0.02 for all visits, respectively), indicative of lens dehydration. These findings although clinically significant are not unique to firefighting, and are found within a "normal" population of contact lens wearers. In conjunction with questionnaire data (Owen et all, 1996) we conclude that soft contact lenses can be worn safely by firefighters without additional risk.

Analysis of Variance↗
PubMed1997

Use of contact lenses by firefighters. Part 1: Questionnaire data.

The use of contact lenses by firefighters is currently prohibited. However, many firefighters may benefit from this form of visual correction, without predisposing themselves to additional risk. Visual benefits gained by contact lens wear may increase a firefighter's safety. To determine if it is safe to allow firefighters to use contact lenses 29 were fitted with soft contact lenses and 21 with rigid gas permeable contact lenses. Questionnaires were completed prior to fitting, after 1, 4 and 10 months of contact lens wear. Both soft contact lens (SCL) wearers, and rigid gas permeable contact lens (RGPCL) wearers showed a statistically significantly reduction in the frequency with which they experience irritable foreign bodies and irritant fumes in the eyes, compared to not wearing contact lenses. Firefighters felt that their performance on the fireground had been improved by the use of contact lenses. SCL wearers also benefited from a reduction in the frequency with which they experienced watery eyes and ocular discomfort. There were significantly fewer problems encountered with SCL wearers than RGPCL wearers. The frequency with which firefighters experienced lenses falling out, lens displacement, watery eyes, ocular discomfort, and operational difficulties was significantly less for the SCL group than the RGPCL group. SCL appear to offer considerable benefits for firefighters with refractive error, but their use cannot be sanctioned without assessment of their effect on the ocular adnexa.

Adult↗
PubMed1996

Optimal photographic imaging of the bulbar conjunctival vasculature.

A method for imaging the conjunctiva to yield greater contrast between the vasculature and the scleral background, by optimisation of the imaging system, is described. A simple modification to the image capture system, based on first principles calculations, is shown to give images with much improved information content. This will enhance the assessment of hyperaemic changes induced by foreign materials, indicating the degree of biocompatibility, e.g. with contact lenses and ophthalmic medications. Observation of vascular abnormalities associated with pathological conditions may assist in their diagnosis and monitor progressive changes.

Adult↗
PubMed1996

Prevalence of spectacle and contact lens wear in the UK fire service.

Despite the fact that firefighting has been shown to be a visually demanding occupation, the present visual standards for firefighters prohibit the use of spectacles or contact lenses operationally. To determine the proportion of the UK fire service currently using spectacles and contact lenses, and how many may benefit from optical correction, a questionnaire was distributed. This contained 30 questions and was sent to 1550 firefighters. The data from 1064 returned questionnaires have been analysed. The results show that approximately 20% of those serving in the fire service have used an optical correction at some time in their lives. When not working, approximately 6% of firefighters wear spectacles for distance vision and 15% wear them for reading. Only 0.4% of firefighters use contact lenses. Half of this contact lens wearing group use their lenses while on operational duty. In total, approximately 2% of firefighters use an optical correction for operational duties. The results indicate that a high visual standard at the time of entry into an occupation cannot guarantee good vision throughout an individual's career. In addition, an estimated 11,000 firefighters in the UK, who have spectacles or contact lenses, do not use them for operational duties. The present visual standards prevent this group of firefighters from obtaining their optimal visual performance at work.

Adolescent↗
PubMed1996

A new computer assisted objective method for quantifying vascular changes of the bulbar conjunctivae.

A novel computer software method was used to quantify the conjunctival plexus on the scleral background for measurement of the vascular surface area from photographs. A previously described method was used (Palmer, J. R., Owen, C. G., Ford, A. M., Jacobson, R. E. and Woodward, E. G. (1996). Optimal photographic imaging of the bulbar conjunctival vasculature. Ophthal. Physiol. Opt. 16, 144-149) to optimise photographic imaging of the bulbar conjuctival vasculature by increasing the information content in the image. Repeatability of this technique was evaluated. Twenty subjects (20 eyes) free from ophthalmological and systemic abnormality were examined on two separate occasions. The maximum 95% confidence limits for repeatability are +8.58/-3.95%. For 10 consecutive estimates of vascularity the maximum 95% confidence interval lie between +/- 6.54%. To evaluate the technique the lateral-bulbar conjunctivaein 10 soft (SCL) and 10 rigid gas permeable contact lens (RGPCL) wearers during the first 10 months of contact lens wear, were assessed and compared with subjective grading of hyperaemia. The new method showed sufficient sensitivity in detecting increased hyperaemia in the RGPCL wearing group and demonstrated statistically significant change. Subjective graded assessment of vascularity (using established classifications) detected increased hyperaemia, however, this was not statistically significant. Conjunctival vasculature is a dynamic structure and a source of valuable quantitative information where the ocular environment is varied, or where the ocular surface is affected by disease. Hence it is worthy of further investigation. A simple inexpensive method of computer assisted determination of vascularity is described.

Adult↗
PubMed1995

Research support by the British College of Optometrists.

The British College of Optometrists has now been in existence for 15 years. One of its first actions was to establish a formal system of research support. The initiation of the scheme and its subsequent expansion is described. In the first year epsilon 5,000 pounds was allocated but current expenditure for 1994/1995 is epsilon 78,671 pounds. Research topics funded are described as are the award of higher degrees by universities and also the current occupation of former scholars. The thesis submission rate for college scholars compares well with those of the major established Research Councils.

Fellowships and Scholarships↗
PubMed1995

Surface wettability and hydrophilicity of soft contact lens materials, before and after wear.

Surface wettability and hydrophilicity of pHEMA soft contact lenses were investigated utilising adherent liquid/laser method (ALLM) and adherent liquid/balance method (ALBM). The measurements were carried out before and after periods of 15 min to 2 h contact lens wear. Following the lens removal, the wetting angle of the contact lens of the left eyes and hydrophilicity (maximum force) of the contact lens of the right eyes of the five subjects were immediately measured, respectively, without cleaning (one value for pre-lens wear and eight values for post-lens wear). The wettability of soft contact lenses significantly increased after 15 min of wearing and stabilised at a maximum level after 30 min in vivo. Contact lens hydrophilicity was found to decrease as the lens was worn. The reduction continued for up to 1.5 h of wearing, for male cases, and for the female cases, the reduction continued until the end of the experiment.

Contact Lenses, Hydrophilic↗
PubMed1995

A novel approach to measuring the wettability of rigid contact lenses. Mass measurement of the adherent liquid on the rigid lens surface (1).

A novel approach and the equilibrium sessile drop (laser assisted) method were used to determine the wettability of hydrated and unhydrated PMMA, Polycon II, Boston IV, Equalens and Boston RXD rigid contact lens materials. In the new method the ability of the contact lens surface to attract the liquid is evaluated by measuring the adhered mass of liquid on the front lens surface. The mass has a direct relationship to contact lens wettability, so the greater the lens surface hydrophilicity the more liquid adheres to the contact lens surface. In the hydrated state, Equalens and Boston IV showed the greatest hydrophilicity of all five materials, although there was no significant difference between them (P > 0.9). Boston RXD had a lower ability to attract liquid and there was a significant difference between it and the next higher material which was Boston IV (P < 0.005) and also the next lowest Polycon II (P < 0.00001). PMMA had the lowest capability to adhere liquid and there was a significant difference between PMMA and Polycon II (P < 0.00001). The new method is simple and quick to use and gives greater discrimination and repeatability than other current methods.

Adhesiveness↗
PubMed1995

Aetiology and prevalence of eye injuries within the United Kingdom fire service.

A survey was conducted on a sample of 1552 firefighting personnel to determine the incidence of eye injuries within the United Kingdom fire service. In total, 3.5% (n = 22/637) of firefighters per year will sustain an eye injury requiring 'medical attention'. This represents one ocular injury per 50,000 working hours. In 80% of cases eye protection was not being worn at the time of injury. Analysis of 75 accident report forms indicates that the vast majority (69/75) of eye injuries were sustained whilst on operational duty. These statistics are comparable to other professions which are considered to have an unacceptably high risk of injury and in which eye protection has therefore been actively enforced. It would follow that similar steps should be taken within the fire service to ensure firefighters wear eye protection on operational duty. This should apply even if there is no immediate recognition of a perceived danger. A firefighter presenting to an optometrist or medical practitioner, with or without an eye injury, should be counselled as to the advantages of eye protection.

Accidents, Occupational↗
PubMed1994

Excimer laser superficial keratectomy for proud nebulae in keratoconus.

Contact lens intolerance in keratoconus may be due to the formation of a proud nebula at or near the apex of the cone. Excimer laser superficial keratectomy was performed as an outpatients with proud nebulae as treatment patients with proud nebulae as treatment for their contact lens intolerance. The mean period of contact lens wear before the development of intolerance was 13.4 years (range 2 to 27 years). Following the development of intolerance, three patients abandoned contact lens wear in the affected eye while the remainder experienced a reduction in comfortable wearing time (mean = 3.75 hours; range: 0-14 hours). All patients had good potential Snellen visual acuity with a contact lens of 6/9 (nine eyes) and 6/12 (one eye). The proud nebulae were directly ablated with a 193 nm ArF excimer laser using a 1 mm diameter beam. Between 100-150 pulses were sufficient to ablate the raised area. Patients experienced no pain during the procedure and reported minimal discomfort postoperatively. In all cases flattening of the proud nebulae was achieved. Seven patients were able to resume regular contact lens wear (mean wearing time = 10.17 hours; range 8 to 16 hours). In three patients, resumption of contact lens wear was unsuccessful because of cone steepness. All patients achieved postoperative Snellen visual acuity of 6/12 or better with a contact lens. Four patients experienced a loss of one line in Snellen acuity. The mean follow up period was 8.3 months (range 2 to 17 months). Excimer laser superficial keratectomy is a useful technique for the treatment of contact lens intolerance caused by proud nebulae in patients with keratoconus. Penetrating keratoplasty is thus avoided.

Contact Lenses↗
PubMed1993

Measurement of corneal topography in keratoconus.

A new method is described for calculating the topography and curvature of an irregularly shaped cornea. Vertical planes of light are projected onto the cornea and points in x, y, z space are calculated from the light images on the corneal surface. A matrix of points is produced on the cornea and a mathematical surface is fitted to them. Using differential geometry theory, curvature values are calculated to find the corneal apex position, apex curvature and curvature change away from the apex. Typical results, in the form of a contour map, are shown for normal corneas and corneas with mild to severe keratoconus. The method gives an accurate quantitative measurement of keratoconic and other irregular corneas.

Anthropometry↗
PubMed1992

Life expectancy in keratoconus.

It is observed that few patients over the age of 60 regularly attend the keratoconus clinic at Moorfields Eye Hospital. The hypothesis that patients with keratoconus have a shorter life expectancy owing to underlying connective tissue related disease was tested. From patient records a sample of 337 keratoconus patients aged at least 40 years by 1991 were identified, of which 279 were living, 13 were deceased, and 45 were untraceable. The mortality rate for keratoconus patients was compared with that of the general population using actuarial English life tables. Results show no significant difference between the general population mortality rate and that of the keratoconus sample even with adjustment for social class. Possible explanations for the non-attendance of older patients are discussed.

Adult↗
PubMed1992

Retrospective study of optometric referrals.

We undertook a retrospective study of the referral patterns of optometrists. During the study period 13,107 patients had been seen, of whom 2.86% had been referred. Of the referred patients, 66.67% were referred to an ophthalmologist via the general practitioner, 25.87% to their general practitioner alone, and 7.47% directly to an ophthalmologist. The conditions for which patients were referred are given along with information on any supplementary tests used. The effect of practitioner age and seasonal variations on referrals was also determined. The role of the optometrist in screening for ocular disease is discussed.

Adolescent↗
PubMed1991

Diffractive bifocal contact lenses in aphakia and pseudophakia. A pilot study.

Diffractive bifocal contact lenses function by diverting incident light to two focal points. Light from near objects is focused by diffraction while that from distant objects is focused by conventional refraction. Both processes occur simultaneously throughout the full aperture of the lens. Fourteen aphakic and pseudophakic contact lens wearers were fitted with diffractive bifocal lenses and observed for an eight week period. Six (42.8%) were satisfied with the visual result. Five subjects (35.7%) discontinued lens wear complaining of poor quality of near vision. We conclude that these lenses may help selected aphakic patients to discard their reading glasses but the low acceptance rate suggests that this type of optic is probably not suitable for implantation as an intraocular lens.

Accommodation, Ocular↗