Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Optometry”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,765 records · Page 98Linked to original sources
PubMed2002

Effect of beta-adrenoceptor antagonists on autonomic control of ciliary smooth muscle.

PURPOSE: Pharmacological intervention with peripheral sympathetic transmission at ciliary smooth muscle neuro-receptor junctions has been used against a background of controlled parasympathetic activity to investigate the characteristics of autonomic control of ocular accommodation. METHODS: A continuously recording infra-red optometer was used to measure accommodation on a group of five visually normal emmetropic subjects under open- and closed-loop conditions. A double-blind protocol between saline, timolol and betaxolol was used to differentiate between the localised action on ciliary smooth muscle and effects induced by changes in stimulus conditions. Data were collected before and 45 min following the instillation of saline, timolol or betaxolol. Open-loop post-task decay was investigated following 3 min sustained near fixation of a stimulus placed 3 D above the subject's pre-task tonic accommodation level. Closed-loop dynamic responses were recorded for each treatment condition while subjects viewed sinusoidally (0.05-0.6 Hz) or stepwise vergence-modulated targets over a 2 D range (2-4 D). RESULTS: Open-loop data demonstrate a rapid post-task regression to pre-task tonic accommodation levels for saline and betaxolol control conditions. A slow positive post-task shift was induced by timolol indicating that sympathetic inhibition contributes to accommodative adaptation during sustained near vision. Closed-loop accommodation responses to temporally modulated sinusoidal stimuli showed characteristic features for both saline and betaxolol control conditions. Timolol induced a reduced gain for low- and mid-temporal frequencies (< 0.3 Hz) but did not affect the response at higher temporal frequencies. Response times to stepwise stimuli increased following the instillation of timolol for the near-to-far fixation condition compared with the controls and was related to the period of sustained prior fixation. CONCLUSIONS: Modulation of accommodation under open- and closed-loop conditions by a non-selective beta-blocker is consistent with the temporal and inhibitory features of sympathetic innervation to ciliary smooth muscle. Although parasympathetic innervation predominates there is evidence to support a role for sympathetic innervation in the control of ocular accommodation.

Accommodation, Ocular↗
PubMed2003

Assessment of information included on the GOS 18 referral form used by optometrists.

PURPOSE: To audit the information included on GOS 18 forms used by UK optometrists when referring patients to an ophthalmologist. METHODS: All GOS 18 forms received in a hospital ophthalmology department over a 10-week period were photocopied and the categories of information presented were recorded. RESULTS: A total of 444 forms were analysed. The two most common referral categories were cataract 36.7% (n = 163) and glaucoma 18.4% (n = 82). Only 7% (n = 11) of cataract referrals included details regarding effect on patient's lifestyle and willingness for surgery. Forty-seven per cent (n = 77) of referrals for cataract resulted in patients being listed for surgery. Eighty-two per cent (n = 67) of referrals for glaucoma included disc assessment, intraocular pressure and visual fields. Five per cent (n = 22) of optometrists gained the patients' consent for release of clinical information. Thirty-one per cent (n = 137) of forms had no practitioner name and 6% (n = 27) gave no practice address. CONCLUSION: Information included on GOS 18 forms could be improved with regard to cataract referrals. Feedback from ophthalmologists would be facilitated by inclusion of practitioner/practice details, and by completion of the consent section on the GOS 18.

Cataract↗
PubMed2003

The combined influence of knowledge, training and experience when grading contact lens complications.

PURPOSE: A study was conducted to evaluate the influence of knowledge, training and experience (clinical skills set) when assessing the severity of contact lens complications. METHODS: Nine optometrists (who were in possession of a relevant clinical skills set) and nine 'non-optometrists' (subjects without the clinical skills set) were each invited to grade - to the nearest 0.1 increment - an image of each of 16 contact lens complications using Efron Grading Scales for Contact Lens Complications. This procedure was repeated 2 weeks later, yielding a total data base comprising 576 individual grading estimates. RESULTS: The mean of the test and retest grading estimates was the same for the optometrists (2.8 +/- 0.7) and the non-optometrists (2.6 +/- 0.9) (F1,15,1 = 1.3, p = 0.26); that is, non-optometrists can grade accurately. Median grading reliability for optometrists (+/-0.41) was lower than (i.e. superior to) that for non-optometrists (+/-0.67) (p = 0.001). Non-optometrists tended to display a reluctance to grade by interpolation and to less reliably grade subtle clinical signs. CONCLUSIONS: When averaged over several attempts, non-optometrists will arrive at similar estimates of severity to optometrists when grading ocular complications of contact lens wear; however, they will do so less reliably. The relative contribution of the three attributes of the clinical skills set to grading performance is presently unclear.

Clinical Competence↗
PubMed2003

Legal issues in contact lens practice with special reference to the practice of orthokeratology.

This report aims to encourage optometrists to reflect on the legal implications of clinical contact lens practice, with particular reference to the practice of orthokeratology (ortho-k), which has seen a recent revival of interest. A patient may claim compensation if an optometrist is negligent by breaching his duty to exercise reasonable care and skill in diagnosis, advice or treatment. However, the optometrist will only be liable for reasonably foreseeable harm to the patient, so practitioners need to be fully aware of the foreseeable risks. Failure to adequately inform the patient may lead to a claim for negligence, if disclosure of the risks would have influenced the patient's decision to undergo or forego the procedure. It is important that the professional bodies establish guidelines on acceptable practice, with particular emphasis on the provision of information to patients. Reasonable disclosure, use of appropriate information/consent forms, and proper documentation of cases, should all focus on the needs of, and benefits to, patients.

Adolescent↗
PubMed2003

Open- and closed-loop regressions compared in myopic and emmetropic subjects.

Post-near task accommodation regressions have been measured in a number of studies to investigate the association between myopia and nearwork. The slow nature of the regression found when measuring both open- and closed-loop regressions in some subjects has been hypothesised to be associated with myopia development and progression. However, it is not known whether the speed and characteristics of the regression for an individual is the same under open- and closed-loop conditions. In this study we measured post-near task accommodation regression functions under open- and closed-loop conditions for myopic and emmetropic subjects. We compared the responses of each subject under the two conditions and found that some subjects responded differently depending on the condition (i.e. a fast regression under one condition and a slow regression under the other condition). When compared as a group, the myopic subjects showed significantly more prolonged open-loop regressions than closed-loop regressions. In terms of the effect on the post-task accommodation, the myopes appear to be more affected by the measurement conditions than the emmetropes in this study. The results highlight the importance of the type of accommodation stimulus when investigating the accommodation response.

Accommodation, Ocular↗
PubMed2003

Evaluating anxiety in patients attending optometric practice.

Although anxiety is a well-established obstacle to the delivery of effective health care, there have been no attempts to measure it in the optometric consulting room. In this paper, we introduce physiological and psychological techniques that may be used to evaluate anxiety and arousal in the consulting room and present data from a small group of patients attending for a routine eye examination. Specifically, arousal was assessed before, during, and after the examination by measuring skin conductance in five patients. Anxiety was evaluated using the State-Trait Anxiety Inventory. Our data confirm the ability of these techniques to quantify arousal and anxiety in the optometric consulting room and reveal a previously unknown but important facet of the eye examination. We conclude that these techniques are suitable for use in further experimental work and may be used to identify factors capable of reducing anxiety in the optometric consulting room.

Adult↗
PubMed2003

The streak retinoscopy pupil reflex in the presence of astigmatism.

Computer simulation is being increasingly used as a teaching tool. Having developed a computer-generated virtual focimeter, we are now in the process of developing a computer-generated virtual streak retinoscope to teach the principles of retinoscopy and the effect of residual refractive error and mirror movement on the pupil reflex. One of the important requirements was to provide as accurate a simulation as possible for the completely general case of an astigmatic patient and a streak in any orientation being moved also in any orientation. This required a thorough understanding of the optical theory of the retinoscope and equations that describe the behaviour of the pupil reflex. We have taken this opportunity to review the optics of the streak retinoscope and derive equations for the behaviour of the pupil streak reflex.

Astigmatism↗
PubMed2003

Sensitivity and specificity of two glaucoma case-finding strategies for optometrists.

Current best practice for primary open-angle glaucoma case-finding comprises history-taking, disc examination, intraocular pressure measurement and suprathreshold visual field analysis (SVFA). An alternative case-finding technique was formulated replacing SVFA with computerised quantitative disc assessment, using the Heidelberg retinal tomograph II (HRT II). Each approach was adopted by four optometrists who screened 29 POAG and 37 normal patients. Average sensitivities and specificities were similar in the two groups [sensitivity 71% (SVFA) vs 69% (HRT II); specificity 94% both groups]. Our inclusion of pre-perimetric glaucoma cases limited the sensitivity of the optometrists in this study. There was evidence to suggest that the optometrists tended to miss early changes at the optic disc such as disc haemorrhage, nerve fibre layer defects and subtle neuroretinal thinning.

Aged↗
PubMed2003

Contact lens fitting following unsuccessful refractive surgery.

A retrospective review of case notes of consecutive patients referred to a contact lens clinic after unsuccessful refractive surgery was carried out to determine the success of contact lens fitting. The main outcome variables in determining success were visual improvement, contact lens tolerance, fitting characteristics and wearing time. Thirteen eyes were fitted with conventional rigid gas permeable (CRGP), 10 with soft and 19 with reverse geometry rigid gas permeable contact lenses (RVG). The mean spectacle visual acuity (VA) was 6/9 (20/30) [range: 6/24 (20/80) to 6/5 (20/15)] and the mean VA after contact lens fitting was 6/6 (20/20) [range: 6/18 (20/60) to 6/5 (20/15)]. Of the 42 eyes, the contact lens VA was better than spectacle acuity in 25 (59.5%) eyes, equal in 14 (33.3%) and worse in three (7.1%). A total of 33 (78.6%) eyes were still wearing their lenses at the last visit. Contact lenses can be a valuable method of managing poor VA after refractive surgery.

Contact Lenses↗
PubMed2003

Optical performance in eyes wearing two multifocal contact lens designs.

The optical performance of eyes wearing soft multifocal contact lenses was studied using the double-pass technique. Retinal image quality was measured in a group of six eyes wearing two different designs of multifocal lenses: an aspheric design and a spheric multicurve design. Measurements were performed for far, intermediate and near vision conditions and with two different pupil diameters: 3 and 5 mm. The results show that the best optical performance is obtained for far vision conditions when no lens is worn. For near vision conditions, the optical performance when the lens is worn is, in general, better than when no lens is worn. When the lens is worn, the optical performance for far and intermediate vision conditions is similar for the aspherical design, but it decreases for near vision conditions. For the spherical multicurve design, the optical performance obtained for far vision conditions is similar to that obtained for intermediate vision conditions for low values of object vergence, but decreases when the object vergence is high and therefore also for near vision. In general, the differences in optical performance are greater for small pupil diameters (3 vs 5 mm). The general trends of the results obtained by computing the modulation transfer function of the contact lens-eye system can also be shown qualitatively by means of double-pass images or quantitatively by computing the Imax/Imed of the image.

Adult↗
PubMed2003

Anterior chamber angle measurement with Anterior Eye Segment analysis system Nidek EAS-1000: improving the repeatability.

Previous studies have reported good intraobserver and interobserver repeatability of anterior chamber angle (ACA) assessment using the Anterior Eye Segment analysis system, EAS-1000. This study investigated the influence of fixation pattern, corneal plotting method and camera position on ACA measurements. A Nidek EAS-1000 system was employed for image acquisition and analysis, to obtain measurements of ACA. Twenty-five young healthy subjects participated. The ACAs were different in different quadrants and using different corneal plotting methods (Repeated measures 3-way anova, p < 0.05). However, the difference was <5 degrees and therefore not clinically significant. Alignment along the visual axis or optical axis did not yield any significant difference. Repeatability was improved by asking the subjects to fixate at the flashing light-emitting diode (LED). Temporal and nasal angles also demonstrated better repeatability than vertical angles. In measuring the vertical angles, the camera can be set at either the temporal or nasal side (Paired t-test, p > 0.05). The Anterior Eye Segment analysis system has good clinical repeatability in measuring ACA. It can be further improved with the use of the flashing LED during image acquisition.

Adult↗
PubMed2003

Criteria for prescribing optometric interventions: literature review and practitioner survey.

The core function of optometrists is the prescribing of refractive corrections, yet a literature review revealed a lack of evidence-based research on criteria for determining when a refractive correction is required. The reported criteria used by practising optometrists were investigated using a questionnaire to survey prescribing habits for borderline hypermetropia, presbyopia, astigmatism, and horizontal and vertical heterophoria. Thirty-eight questionnaires were returned and the results analysed. We calculated the 'cut off' point above which the anomaly would be corrected over 50% of the time that it was encountered. There was a large variation for each category, but it was clear that the presence or absence of symptoms was an important factor for most optometrists when deciding whether to correct a small error. It was found that for symptomatic patients, most optometrists would correct an anomaly if it reached: +1.00 D of hypermetropia, a reading addition of +0.75 D for presbyopia, -0.75 DC of astigmatism, 1.5 prism dioptres (Delta) of horizontal aligning prism, and 1 Delta of vertical dissociated heterophoria. For asymptomatic patients, optometrists would not correct any of the hypermetropic anomalies or heterophorias that were specified in our questionnaire. However most would correct a presbyopic error of +1.50 D or above, or an astigmatic error of -1.50 DC or above, even in the absence of symptoms. These results were compared with previously published guidelines.

Adult↗
PubMed2004

Assessment of delays in presentation of patients with retinal detachment to a tertiary referral centre.

The referral pathway of patients with retinal detachment from primary care providers to a tertiary care ophthalmic unit was examined, in order to determine the length and source of any delays between the onset of symptoms and arrival at the hospital. A prospective survey of all symptomatic patients (n = 60) admitted for primary rhegmatogenous retinal detachment surgery was carried out over an 8 week period. Twenty-one patients were referred by their optometrists and 18 by their general practitioners. The remainder were referred by local accident and emergency and ophthalmic departments or presented directly to the tertiary referral centre. Patients who presented to their optometrists were symptomatic for an average of four times longer. More than half the patients thought that the time to initial presentation was the most significant delay. Referral from optometrists via general practitioners and local ophthalmic clinics was considerably longer. Increased awareness of symptoms, necessity of urgent referral and knowledge of available services locally may reduce delay for those who require emergency sight-saving surgery.

Adolescent↗
PubMed2000

[Measurement of eye length and eye shape by optical low coherence reflectometry].

BACKGROUND: The precise and rapid measurement of eye length and eye shape are essential for investigating eye growth regulation and myopia. For this purpose, we developed an optical low coherence reflectometer and obtained preliminary measurements in volunteers. METHODS: The instrument includes a rotating glass cube to produce longitudinal scans at a velocity of 0.42 m/s and a repetition rate of approximately 13 scans/s. Heterodyne detection of light reflected from the anterior cornea and the posterior retina permits to measure axial eye length and eye shape (off-axis eye length). Each measurement consists of five consecutive scans. Reproducibility and precision were determined in one volunteer by measuring axial eye length five consecutive times, each time repositioning the eye. Eye shapes were determined in right eyes of four volunteers by measuring eye length every 3.3 degrees from 10 degrees nasally to 10 degrees temporally. RESULTS: Axial eye length measured repeatedly in one volunteer did not differ between or within the measurements (one-factor ANOVA). The average standard deviation was 11 microns. Eye shapes a) varied substantially among subjects and b) differed considerably from the corresponding shapes of spherical model eyes with identical axial eye lengths. CONCLUSION: The newly developed reflectometer permits the precise and rapid measurement of eye length and eye shape. Such measurements, especially in children, may provide important information about mechanisms of eye growth regulation and the development of myopia.

Eye↗
PubMed1988

[A rare trial eyeglass case with binocular trial lenses].

In this article the author describes a rare trial frame case in the medical history collection of the Ruhr University at Bochum. It has 24 binocular trial lenses which are similar to be early "Nuremberg wire spectacles." The lens power is expressed as the focal length, measured in Rhenish inches. Converted into diopters, the refractive power of the lenses ranges from +/- 1.0 to +/- 8.0 D.spherical. The case also contains six pairs of plane lenses tinted in various intensities of azure blue and four pairs of plane lenses tinted smoke-gray. It contains no astigmatic lenses. Since the metric system, with the diopter as a unit of refractive power, was introduced in the optical industry in 1875, it may be assumed that this case was in use before then. However, the design of the binocular trial frames suggests that they may be considerably older.

Eyeglasses↗
PubMed1982

[Accommodation as the primary cause of night myopia].

Night myopia can now be measured accurately with a laser optometer. An increasing number of reports, based on work with this optometer, have supported the hypothesis that night myopia is caused by accommodation. In this study subjects with one phakic and one aphakic eye were tested with respect to the magnitude of night myopia developed in each eye. The results appear to represent the first direct experimental evidence for the hypothesis that accommodation is the primary cause of night myopia.

Accommodation, Ocular↗