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Biomedical subjects

L F Garner

Publications and source records attributed to L F Garner.

32 records · Page 2Linked to original sources
PubMed1986

Eye protection from airborne allergens.

The need for eye protection from hazards such as flying objects, particles, dust, noxious gases and chemicals is well established, and is part of normal safety procedures where these hazards exist. There have been recent reports that eye protection from airborne allergens may be an effective method for reducing the symptoms of allergic conjunctivitis and hay fever. This review examines the literature on these devices which appear to offer an alternative to conventional drug therapy.

Allergens↗
PubMed1985

Some visual effects caused by the beverage kava.

Kava is a drink produced from the plant Piper methysticum and used as a social and ceremonial beverage on many South Pacific islands. Visual functions were measured in one subject following the taking of this drink. A reduced near point of accommodation and convergence, an increase in pupil diameter and disturbance to the oculomotor balance were noted. No changes were recorded in visual or stereoacuity or in ocular refractive error.

Adult↗
PubMed1985

Prevalence of myopia in school children in Vanuatu.

The onset of myopia typically occurs in childhood and increases during puberty. We studied the vision and refractive errors of 977 school children (ages 6 to 17 years) in 1983. Myopia in the group was extremely low; 97% had vision of 6/6, and 1.3% had myopia greater than 0.25D. Regression analysis revealed a change in mean refraction of -0.016D/year for males and -0.024D/year for females. There were no significant differences between males and females. These children engaged in about 8 hours of school work per day, and we conclude that genetic factors predominate over environmental factors in the determination of myopic refractive errors for this group.

Adolescent↗
PubMed1985

Use of an automatic refraction device in a Third World country.

The vision welfare services in many Third World countries are compromised by the shortage of trained ophthalmic vision care workers. We investigated the feasibility of fulfilling part of the needs in this area by training local personnel in the use of automatic refraction devices. A nurse from the Vila Base Hospital in Vanuatu was given minimal training in the use of such an instrument (Nikon NR 2000), and given guidelines for the preparation of ophthalmic prescriptions. Sixty-nine subjects in the Village of Mélé in Vanuatu were seen by both the nurse and an optometrist, and the prescriptions issued by both workers were compared. The use of automatic refractors under those conditions holds promise for filling the needs in Third World countries, and suggestions are given for adapting these instruments for the particular conditions encountered during this study.

Adolescent↗
PubMed1984

Vision care in New Zealand.

This paper reports the results of a study into attitudes on vision care, vision care professionals and the utilisation of various ophthalmic aids and appliances in New Zealand. The majority (70%) of the 2000 persons questioned had received a visual examination by an optometrist or ophthalmologist and were either "very satisfied" or "satisfied" with the treatment they obtained. Of those that had had a recent visual examination, ophthalmologists examined 22% and optometrists examined 72%. Three percent of the total sample (ie, 8% of ophthalmologists' patients) had received surgical or medical treatment at their last examination. Sixty-six percent reported that they did not have any of the visual or ocular problems listed. Of the remaining 34% who were currently having problems, 64% had not sought professional advice for that problem. Of the remainder that had sought some advice, approximately equal numbers had visited a general medical practitioner (11%) or optometrist (12%) and 5% had seen an ophthalmologist. For those without problems, 42% said they would visit their general medical practitioner and 41% said they would visit an optometrist if they were to develop any of the problems listed. For respondents that had either private medical insurance or would consider joining such a scheme, about 78% would prefer a policy with optometric benefits at the premiums quoted.

Adolescent↗
PubMed1984

Ophthalmic services in New Zealand.

A random sample of 2000 persons throughout New Zealand was questioned on the use of and attitudes toward vision care. One-half of the respondents had had a vision examination within the past 4 years. Of those that had been examined, 72% were seen by an optometrist and 22% were seen by an ophthalmologist. Fifty-two percent of the sample wore spectacles or contact lenses, and in the 25 to 34 year age group 12.5% wore contact lenses. The majority (66%) reported no visual problems, and of this group 42% would visit a medical practitioner, 41% an optometrist, and 11% an ophthalmologist if they were to develop a visual problem. At the last visual examination 28% were advised that they did not need a refractive correction, 22% were told their present aid was adequate, and 46% were prescribed new spectacles.

Adolescent↗
PubMed1983

Effects of luminance on contrast sensitivity in senile macular degeneration.

Patients with senile macular degeneration (SMD) often have difficulties in adapting to changing luminance levels. They may complain of problems at both high and low luminance levels, although some patients have their vision function markedly improved at high luminance levels. We examined the effect of luminance on the contrast sensitivity function in six patients with SMD and five normals of approximately the same age. The contrast sensitivity of the SMD patients compared to the control subjects was reduced at 72 cd/m2 but was comparable to that of the controls at 0.007 cd/m2. The peak of the contrast sensitivity function was moved to lower spatial frequencies at all luminances in the SMD group, and the slope of the function relating contrast sensitivity to luminance was reduced. These data suggest that adaptation mechanisms which optimize contrast detection are disrupted in SMD. Further disturbances of function might be expected in the dynamics of the adaptation process.

Adaptation, Ocular↗
PubMed1983

Mechanisms of accommodation and refractive error.

The classical or Helmholtz theory of accommodation has formed the basis of optometric practice for many years. This theory maintains that the ciliary muscle receives only parasympathetic innervation and that the position of rest in the emmetropic eye lies at optical infinity. The suggestion of a dual sympathetic/parasympathetic innervation to the ciliary muscle also dates from the last century. Recent studies indicate that the "dark focus" or resting point of accommodation lies at some intermediate distance and that the refractive state in the absence of an adequate stimulus represents the tonus position of the ciliary muscle for minimal autonomic innervation. This paper considers the possible role of a sympathetic innervation to the ciliary muscle in the development and correction of refractive errors.

Accommodation, Ocular↗
PubMed1983

The effect of phenylephrine hydrochloride on the resting point of accommodation.

Previous models for ocular accommodation have suggested a dual sympathetic/parasympathetic innervation to the ciliary muscle. Such models would predict that sympathomimetic drugs should change the resting point or dark focus of accommodation. The effect of an alpha-adrenergic agonist (10% phenylephrine hydrochloride) on accommodation was examined; the results show a decrease in the near point of accommodation, without a change in the resting point of accommodation. These results suggest that the accommodative state of the eye is not the result of a simple balance between sympathetic and parasympathetic innervation as proposed by previous models of accommodation.

Accommodation, Ocular↗
PubMed1982

Sagittal height of the anterior eye and contact lens fitting.

A mathematical model for calculating the saggittal height of the anterior eye is used to study the effect of variation in ocular dimensions on the sagittal height of the eye. Examination of the relation between sagittal height and contact lens fitting reveals that the three-point touch theory is not inconsistent with normal fitting procedures for semiscleral soft lenses.

Contact Lenses↗
PubMed1981

The effect of fenestrating soft contact lenses on corneal swelling.

Nine subjects wore fenestrated and unfenestrated soft contact lenses for 6-hr periods. The lenses worn in the experimental eye were fenestrated with four, 0.80-mm holes, located in the midperipheral region of the lens. THe corneal swelling was monitored with a biomicroscope and pachometer and the fenestrations significantly reduced the corneal swelling compared with the same lens worn prior to fenestration.

Adolescent↗
PubMed1981

A simple interferometer for hard contact lenses.

A method is described for assessing the back surface of hard contact lenses using an interference technique. The application of the method to the measurement of the peripheral zones of some lens designs is described with measurement data for two aspheric designs. Examples of qualitative assessment of lens surfaces are included. The instrument employed is a low-power stereo-microscope, such as is common in contact lens practice.

Contact Lenses↗
PubMed1977

The effect of corneal edema on visual function.

Corneal edema was produced by atmospheric-induced anoxia and the visual effect was assesed by conventional acuity tests and compared with contrast sensitivity measurements. For the degree of edema which this technique produced, contrast sensitivity was depressed for only high spatial frequencies and could be considered in terms of equivalent defocus. This was not the case ofr a greater degree of edema which was simulated by a diffuser with a particle size that mimics the diffraction effects from an edematous cornea. Equivalent blur was not applicable, since low spatial frequencies were also affected and the letter and contrast sensitivity tests gave radically different results. In the light of these findings, the validity of the present letter acuity evaluation of visual function for patients in which intraocular scattering is involved is questioned.

Cornea↗