The primary eye care examination: opening the case history and the patient's uninterrupted initial talking time.

PURPOSE: The uninterrupted initial talking time (UITT) of optometric patients was measured in response to the clinician's opening question: "Do you have any problems with your eyes or your sight?" METHODS: UITT was measured surreptitiously by the optometrist. Also noted was whether an eye/sight problem was claimed by the patient and whether or not this was subsequently confirmed by the examination. RESULTS: Data were collected from 822 adults, mean age 59.1yrs (SD 17.6), range 16.0-92.0yrs. UITT data were positively skewed; median value 28.87s (IQR 19.81-43.03s) and no statistically significant difference between genders (p=0.9). 53% of patients had completed their opening statement by 30s, and 90% after 1min. 75% of these individuals (age range 26-75yrs) had a median UITT 27.82s; younger patients (16-25yrs) spoke for a significantly shorter time (18.39s: p=0.002) and elderly patients (≥76yrs) a significantly longer time (37.27s: p=0.003) than the majority value. Previously unexamined patients, habitual spectacle wearers, and individuals presenting with an eye/sight problem all recorded a significantly longer UITT (p≤0.006) than their peers. The practitioner's opening question had a sensitivity of 0.54/specificity of 0.95, and a positive predictive value (PV) of 0.78/negative PV of 0.87: with a calculated value of κ=0.53, the strength of agreement between subjective claim and objective outcome could be regarded as 'moderate'. CONCLUSION: These data suggest that an optometric patient's UITT of <30s is unlikely to prove disruptive to the clinical routine.

The interpupillary distance in adult Caucasian subjects, with reference to 'readymade' reading spectacle centration.

PURPOSE: The magnitude of the far interpupillary distance (FIPD) has recognized significance within and beyond clinical optometry. Quantitative information regarding the lesser-reported near parameter (NIPD) would similarly be of interest, and could be of relevance with regard to the visual comfort obtained with 'readymade' reading spectacles. METHODS: Mensuration statistics relating to the FIPD and NIPD are presented, as collated from the spectacle dispensing records of n = 1354 healthy Caucasian presbyopic subjects. The FIPD data were partitioned across 4 age bands (by decade, 41-80 years of age): the NIPD data were distributed across seven nominal reading powers (in 0.50 D steps, +1.00 to +4.00 D). The results of these analyses are considered here, along with their potential application. RESULTS: Consistent gender (male > female) and classification (far > near) differences in IPD (both of approximately 3 mm) were confirmed throughout these data. The magnitude of the adult FIPD is in accord with previously published results; this dimension is now supplemented by NIPD values, whose relationship with total near power is also described. CONCLUSIONS: This new anthropometric survey indicates that inter- and intra-gender interocular facial measurement stability is a characteristic of presbyopic subjects. It is suggested that across the anticipated range of age and total reading power requirement of Caucasian (White Northern European) wearers of 'readymade' reading spectacles, adoption of a standard optical centration distance of 61 mm would be universally appropriate.

Patterns of refractive change in myopic subjects during the incipient phase of presbyopia: a preliminary study.

PURPOSE: Changes in refractive error are well documented over the typical human lifespan. However, a relatively neglected period of investigation appears to be during the late fourth decade; this is at the incipient phase of presbyopia (IP), where the amplitude of accommodation is much reduced and approaches the level where a first reading addition is anticipated. Significantly, informal clinical observation has suggested a low incidence of an unexpected abrupt increase in myopia during IP. METHODS: We investigated this alleged myopic shift retrospectively by mapping the longitudinal refraction histories of normally-sighted 35-44 years old British White patients previously examined in routine optometric practice. The refractive trends in the right eyes of healthy myopic subjects (spherical equivalent refraction, SER ≤-0.50 D: N=39) were analysed relative to that point at which a first near dioptric addition was considered to be clinically useful. RESULTS: A refractive change was evident in some subjects during IP; viz, an abrupt increase in myopic SER of between -0.50 and -0.75 D. These individuals (N=8) represented 20% of the study population of myopic incipient presbyopes. Beyond the pivotal point of the first near addition the longitudinal refraction stabilized in these subjects. In contrast, and as the extent of the available longitudinal data would permit, the remaining myopic eyes maintained an approximately stable refractive trend throughout IP and beyond. CONCLUSIONS: The anatomical or physiological basis of this specific late (non-developmental) abrupt myopic refractive change is an intriguing issue. Axial (vitreous chamber elongation), corneal (contour) and lenticular (profile and index) power bases, alone or in concert, might be considered candidates for this hitherto unexplored refractive phenomenon. Although necessarily obtained under conventional conditions of central (0 deg) fixation, our data might also be a reflection of the recent recognition of the possible influence of the peripheral refraction upon the axial error. Consideration of this material provides an impetus for further research, including ocular biometry, a reappraisal of ciliary zonular functional anatomy, renewed investigation of the AC/A ratio, and the extent of a centripetal refractive influence on myopia development.

Habitual vs optimal distance visual acuity.

PURPOSE: The maintenance of a good level of vision is desirable for developmental and social reasons; it is also a requirement that should not be overlooked in the clinical research environment. This study set out to quantify and analyse any difference between 'habitual' (pre-sight test) and 'optimal' (post-refraction) distance visual acuity in an optometric population. It is intended that the outcome of this work will inform not only clinicians but also those undertaking vision research. METHODS: Binocular logMAR visual acuity was determined at 6 m before and after optometric intervention in patients attending optometric practice for a routine sight test. Cases were recorded seriatim but restricted to the 'core' refraction range representative of typical optometric practice; three further exemption criteria included subject illiteracy, the necessity for a non-standard test distance and contact lens wear. Over a 12-month period, two-thirds of patients examined satisfied the study inclusion criteria; it is the clinical data of these 1288 individuals that are described and analysed here. RESULTS: These data provide a quantitative demonstration that an optometric intervention will most likely improve the habitual distance visual acuity of subjects, irrespective of gender, age group, time interval since last test, refractive status and whether or not the subject is a habitual spectacle wearer. The improvement found was typically within one logMAR chart line (<5 letters), being greatest in spectacle-wearing teenagers and in individuals beyond retirement age (increasing to eight letters in elderly habitual non-spectacle wearers); also in non-wearers who left an interval of 2 years or more between sight tests. CONCLUSIONS: Clinical and laboratory-based investigators are advised that a current and optimal refractive correction should be worn by subjects of all ages enrolled in vision-related studies. Refractive defocus may introduce or exaggerate test outcome variability.

Influence of selected variables on monocular, interocular, and binocular visual acuity.

PURPOSE: The accurate determination of a patient's monocular and binocular visual acuity (VA) is a key feature of any ophthalmic examination. The work reported here was undertaken to inform the acuity assessment procedure by establishing the influence of test sequence, patient gender, and sensori-motor laterality preference on monocular, interocular, and binocular VA values. METHODS: The test protocol required the determination of independent monocular acuities (testing right and left eyes in a randomized sequence), followed by the binocular value, in each of 100 prepresbyopic subjects conforming to specific selection criteria. A set of Landolt-ring logMAR charts for use at 20 ft (6 m) was produced for this task. In addition, the sighting eye and preferred hand of each subject were established using recognized techniques. RESULTS: The order of monocular vision testing was found to have no statistically significant influence on the VA level recorded. The group mean acuity of the left eye exceeded that of the right by 0.005 logMAR units, a difference of no statistical significance. Compared with female subjects, males revealed a consistently, statistically significant higher group mean acuity of about 0.02 logMAR units (> or =1 logMAR chart symbol). However, the clinical significance of this outcome and the relatively superior left acuity might both be regarded as doubtful. Binocular visual resolution was 13% greater than the mean monocular value. Associations between combinations of preferred eye, writing hand, and better-sighted eye were at levels no greater than chance would predict. CONCLUSION: Informed by these results obtained upon visually-normal subjects, the importance of technique and the need to test a patient's VA to threshold is stressed, not only in the context of appropriate clinical case handling but also with regard to accurate record keeping.

Poor recognition of the UK minimum driving vision standard by motorists attending optometric practice.

PURPOSE: To evaluate the current level of recollection of the vehicle number plate viewing distance in a group of motorists. Knowledge of this distance is required to self-check compliance with the UK legal minimum driving vision standard. METHODS: A cohort of 480 motorists aged > or =17 years attending optometric practice for a routine sight test agreed to participate in a short verbal survey. They were asked whether they could state the current UK statutory vehicle number plate viewing distance as specified in the Highway Code. Also recorded were each motorist's high contrast logMAR visual acuity, whether or not an optical prescription was habitually worn when driving, and brief demographic details (age, gender). RESULTS: No statistically significant gender-based difference was present in age distribution, mean logMAR binocular acuity, or age and number (proportion) of motorists who habitually wore a refractive correction when driving. The level of mean binocular acuity was uniformly good (<0.0 logMAR, or better than 6/6 Snellen). However, the recollection by respondents of the statutory viewing distance was poor: only 5% were able to state correctly the current distance (20 m), and 22% recalled the previous (20.5 m/67 ft) or the original (22.9 m/75 ft) statutory distance. Of the remainder, 28% underestimated and 45% overestimated the distance. A statistically significant gender-based difference (p = 0.01) between the recollections of non-prescription wearers became marked (p = 0.001) for habitual wearers, in which latter case the median value and range of estimates by female motorists was greater than their male counterparts. CONCLUSIONS: The level of recognition by these motorists of the viewing distance necessary to satisfy the legal minimum vision standard required for driving on UK roads was low and comparable to the levels recorded in two similar surveys undertaken by other authors 10 and 20 years ago. An inexpensive and easily implemented publicity innovation is suggested which could help improve driver appreciation of the statutory distance and promote compliance with the legal vision standard.

The absence of lateral congruency between sighting dominance and the eye with better visual acuity.

The notion that in subjects with normal binocular vision (i.e. non-strabismic cases) the eye showing sighting dominance will also most likely be that individual's better-sighted eye has proved to be persistent. A review and analysis of the literature has now demonstrated, across several population groups, the fallacy of this belief. In fact, the occurrence of lateral congruency between sighting dominance and the eye with better visual acuity is at a statistical level no greater than chance would predict. Some clinical implications of this outcome are considered.

An enhancement to the Maddox Wing test for the reliable measurement of horizontal heterophoria.

PURPOSE: To attempt to improve the reliability of the Maddox Wing (MW) test for the measurement of horizontal heterophoria at near. METHODS: Horizontal heterophoria measurements at 30 cm using the MW instrument were made on a group of 58 normally-sighted binocular young adult subjects. The procedures were repeated at each of five weekly visits. The standard tangent scale card provided by the instrument's manufacturer was used as the control condition vs four alternative cards designed to enhance accommodative stimulation and improve operational reliability. RESULTS: A statistically-similar mean near phoria value was recorded using each of the five cards. However one of the alternative card designs produced a small but statistically significantly less variable result than the others: this design featured a much smaller typeface (4pt) than that used for the digits on the standard card, and the horizontal row of numbers was flanked by two periods of a low spatial frequency (< 2 c deg(-1)) square wave grating. CONCLUSIONS: It is suggested that for improved reliability of near phoria measurement when using the MW instrument a more appropriately detailed design of tangent card would promote enhanced accommodation, an operational consideration likely to be especially relevant when examining children.

Clinical characteristics of unilateral myopic anisometropia in a juvenile optometric practice population.

PURPOSE: A retrospective study of longitudinal case histories, undertaken to establish the clinical and statistical characteristics of unilateral myopic anisometropia (UMA) amongst the juvenile and adolescent population at an optometric practice, is reported. UMA was defined as that specific refractive state where an unequivocally myopic eye is paired with a 'plano' [spherical equivalent refraction, (SER) = +/-0.25 Dioptres (D)] companion eye. METHODS: The clinical records of all patients aged <19 years on file at an established independent optometric practice were categorised as 'myopic' (SER < or =-0.50 D), 'hypermetropic' (> or =+0.75 D) or 'emmetropic' (> or =-0.37< or =+0.62 D). Subsequently all juvenile patients matching the UMA criterion, together with a case-matched group of bilaterally myopic individuals, were selected as the comparative study populations. RESULTS: A total of 14.4% (n = 21 of 146) of the juvenile myopic case histories were identified as cases of UMA. More than half of these UMA cases emerged between the ages of 11.5 and 13.5 years. There was a marked female gender bias. The linear gradient of the age-related mean refractive trend in the myopic eye of the UMA population was not statistically significantly different (p > 0.1) to that fitted to the ametropic progression recorded in either eye of the case-matched population of young bilateral myopes; uniquely the slope associated with the companion eye of UMA cases was statistically significantly (p < 0.025) less steep. Compared with bilateral myopes fewer cases of UMA required a refractive correction to relieve visual or asthenopic symptoms, and this initial correction was dispensed on average 1 year later (at age 12.7 years) in UMA patients. CONCLUSIONS: Individuals identified as demonstrating clinically-defined UMA can be considered as distinct but functionally normal cases on the continuum of human refractive error. However, any unilaterally-acting determining factor(s) underlying the genesis of the condition remain obscure.

A novel visual analogue scale (VAS) device: an instrument based on the VAS designed to quantify the subjective visual experience.

PURPOSE: To evaluate a novel device intended to facilitate the direct quantification of the subjective visual experience. The design principle is based on that of the visual analogue scale (VAS) technique but obviates the need for subsequent measurement unlike the administration of the conventional paper VAS. METHODS: The visual experience of 134 normally sighted 17-40-year-olds was quantified using (in randomised sequence) a paper VAS and the novel VAS device. A notional 100-point scale was utilised in either case, and the extreme descriptive anchors for both instruments were 'dreadful' and 'perfect'. RESULTS: The degree of clinical agreement between the two alternative VAS techniques was very high. A small bias (mean = +0.7 VAS units: 95% confidence interval 0.3-1.2 units) towards the paper VAS was evident in these data, an outcome of no clinical significance or impediment as regards the substitution of the novel device for the conventional paper-based approach. CONCLUSIONS: The moving of a bead along a wire is shown to be a clinically and statistically reliable alternative procedure to the pen-marking of a conventional paper VAS for the evaluation of the recent subjective visual experience, provided that the same minimum/maximum descriptive anchors are used for either instrument. The instant quantification of the VAS score afforded by the novel technique introduced here broadens the potential clinical application of this technique.

Evaluating the visual experience: visual acuity and the visual analogue scale.

PURPOSE: To attempt a comparison of the visual experience [assessed using a visual analogue scale (VAS)] with visual acuity in a group of normally-sighted adult optometric patients. METHODS: A single-item 100 mm paper VAS was administered to a sequence of 142 normally-sighted pre-presbyopic patients. Each individual was invited to indicate their recent subjective distance visual experience between the extremes of 'dreadful' (0 mm) and 'perfect' (100 mm). Each patient's binocular visual acuity was then determined at 6 m using a high-contrast logMAR chart under usual consulting room conditions. RESULTS: A weak association was revealed between the subjective indication of recent visual experience and the actual level of binocular acuity recorded in this normally-sighted group of subjects. On the basis of group responses a statistically significant discontinuity in the scores recorded with the VAS was demonstrated between patients who attained a clinical acuity better or worse than 0.10 logMAR units (6/7.5). Patient gender, age, and whether spectacles were habitually worn for distance viewing, were each revealed to be not statistically significant features. CONCLUSIONS: For normally-sighted optometric patients the subjective criterion of visual satisfaction would appear to be only loosely associated with the contemporaneous record of clinical acuity.

Border distinctness in amblyopia.

On the basis of the contrast sensitivity loss in amblyopia which mainly affects higher spatial frequencies, one would expect amblyopes to perceive sharp edges as blurred. We show that they perceive sharp edges as sharp and have veridical edge blur perception. Contrary to the currently accepted view, this suggests that the amblyopic visual system is not characterized by a blurred visual representation.

Gender-related optical aspects of the onset of presbyopia.

Evidence is presented which substantiates the frequent clinical impression that female optometric patients require their first reading prescription at a slightly earlier age than males. Furthermore newly presbyopic females require an initial add of slightly greater magnitude than age-matched males. A high (>+1.50 D) first add requirement is revealed as a predominantly male characteristic, an outcome attributable essentially to their often relatively later age of presentation for an initial presbyopic refractive examination.