Does using a bioptic telescope improve visual recognition of the on-road environment?

SIGNIFICANCE: Individuals with reduced visual acuity (VA) may drive with bioptic telescopes in some jurisdictions. The effect of bioptic telescope use on on-road recognition distances is important for driving safety, as increased recognition distances increase the time available to react to road signs or driving events. PURPOSE: This study aimed to investigate the impact of bioptic telescope use on visual recognition of road signs, traffic lights, and hazards in an on-road driving environment in individuals with reduced VA. METHODS: Ten individuals (mean ± standard deviation age, 39.1 ± 19.1 years) with reduced VA (trained to use bioptic telescopes) participated in a repeated-measures on-road experiment for two viewing conditions, with and without a bioptic telescope (randomized order). Participants underwent a clinical low vision assessment, including high-contrast VA with and without the bioptic telescope aligned, visual fields, and contrast sensitivity testing. For the driving component, participants seated in the front passenger seat of a moving car reported all road signs, traffic lights, and hazards (unpredictable road events that represent a risk to driving safety including other vehicles, cyclists, pedestrians) seen along a route that included suburban roads and highways. Video cameras captured participants' viewing behavior, verbal commentary, and the distance at which three pre-selected road signs were reported. RESULTS: In the eye with the bioptic telescope, high-contrast VA improved from 0.75 ± 0.17 (without) to 0.25 ± 0.1 logMAR with the bioptic telescope. Bioptic telescope use did not affect the percentage of road signs, traffic lights, or hazards correctly recognized but did result in 2.6 times longer recognition distances (49 ± 23 vs. 19 ± 11 m, t9 = 5.02, p<0.001). CONCLUSIONS: Road signs were recognized at significantly longer distances when using a bioptic telescope, confirming their positive impact on timely visual recognition of objects within the driving scene. Future work should explore whether this effect generalizes to individuals using bioptic telescopes when driving a vehicle.

Can Tinted Lenses Be Used to Manipulate Pupil Size and Visual Performance When Wearing Multifocal Contact Lenses?

BACKGROUND: The purpose of this study is to investigate the effect of wearing neutral density (ND) filters with different transmittance levels over multifocal contact lenses (MTF CLs) on pupil size, visual functions and the dynamic accommodative response under daylight conditions in early presbyopes. METHODS: Seventeen individuals aged between 40 and 48 years (mean age 42.35±2.62 years) were recruited to participate in this study. This study involved a repeated-measures design with two within-subject factors: optical condition (which had five levels), and fixation distance (which had three levels). The five optical conditions were no correction (baseline), MTF CL wear, MTF CL wear + 0.3 ND filter (transmission [Tv]=48.38%), MTF CL wear + 0.6 ND filter (Tv=27.12%) and MTF CL wear + 0.9 ND filter (Tv=14.58%). The three fixation distances were 3 m, 40 cm and 20 cm. Outcome measures were pupil size, the measured accommodative response (optical aid + physiological accommodation), distance visual acuity (VA), near VA and contrast sensitivity (CS). RESULTS: There was no effect of optical condition on the accommodative response; however, there was a significant effect of fixation distance. (Accommodative response was 0.44±0.29, 1.83±0.37 and 4.03±0.46 D for fixation distances of 3 m, 40 cm and 20 cm, respectively; p<0.05.) There was a significant effect of optical condition (p<0.05) and of fixation distance on pupil size variation (5.13±0.90 mm for 3 m, 4.71±0.92 mm for 40 cm and 4.11±1.04 mm for 20 cm; p<0.05). Optical condition had a significant effect on distance VA, near VA and CS (p<0.05). Compared to the reduction in distance VA, near VA was relatively small (two-letter reduction with 0.9 ND) and unlikely to be clinically significant. CONCLUSION: This study demonstrated that in a group of adults with early presbyopia, the use of ND filters enlarged pupil size. However, the combination of enlarged pupils and MTF CL did not improve distance vision, and if transmittance was reduced by 50% it resulted in decrements in vision and CS. MTF CL designs which incorporate tints, or tints that vary in darkness in response to ultraviolet exposure, should consider these findings.

Comparing spectacle and toric contact lens prescribing trends for astigmatism.

BACKGROUND: The purpose of this study is to investigate and compare spectacle and contact lens (CL) prescription trends, with an emphasis on astigmatic refractive error prescribing differences for patients who purchase spectacles or CLs in South Korea. METHODS: A retrospective study of patient records of a major optical chain in South Korea was conducted. De-identified data of age, gender, power of prescribed spectacles and/or CLs were extracted from the practice database. Inclusion criteria were being within the first 10,000 purchasers of spectacles or CLs or both. RESULTS: The first 10,000 purchases comprised spectacles (59%) and CLs (41%) (male:female ratio 4:6). The proportion of purchasers who were female was significantly higher for CLs (88% female, 12% male) than spectacles (43% female, 57% male) (χ 2 =4480.36, df=1, P<0.0001). There was a significant difference in the proportions of purchases by age group for spectacles and CLs (χ 2 =3246.69, df=3, P<0.0001). Spherical power distribution of prescribed lenses was similar between the groups; however, cylinder power and axis were significantly different (P<0.0001). CL astigmatic powers were more likely to be 1.00 DC or greater, whereas the majority of spectacle lenses had astigmatic power of 0.75 DC or less. In total, 90% of toric CLs were prescribed ×180 and 9% other meridians, unlike spectacles where 50% were prescribed ×180, 14% ×90 and 40% at oblique meridians. CONCLUSION: There is scope for providing increased toric lens correction amongst CL wearers and increasing the proportion of wearers who are male. The estimated gap for toric lens prescription amongst CL wearers who have clinically significant astigmatism ≥0.75 DC is about 59%.

Fractal Dimension Analysis of Transient Visual Evoked Potentials: Optimisation and Applications.

PURPOSE: The visual evoked potential (VEP) provides a time series signal response to an external visual stimulus at the location of the visual cortex. The major VEP signal components, peak latency and amplitude, may be affected by disease processes. Additionally, the VEP contains fine detailed and non-periodic structure, of presently unclear relevance to normal function, which may be quantified using the fractal dimension. The purpose of this study is to provide a systematic investigation of the key parameters in the measurement of the fractal dimension of VEPs, to develop an optimal analysis protocol for application. METHODS: VEP time series were mathematically transformed using delay time, τ, and embedding dimension, m, parameters. The fractal dimension of the transformed data was obtained from a scaling analysis based on straight line fits to the numbers of pairs of points with separation less than r versus log(r) in the transformed space. Optimal τ, m, and scaling analysis were obtained by comparing the consistency of results using different sampling frequencies. The optimised method was then piloted on samples of normal and abnormal VEPs. RESULTS: Consistent fractal dimension estimates were obtained using τ = 4 ms, designating the fractal dimension = D2 of the time series based on embedding dimension m = 7 (for 3606 Hz and 5000 Hz), m = 6 (for 1803 Hz) and m = 5 (for 1000Hz), and estimating D2 for each embedding dimension as the steepest slope of the linear scaling region in the plot of log(C(r)) vs log(r) provided the scaling region occurred within the middle third of the plot. Piloting revealed that fractal dimensions were higher from the sampled abnormal than normal achromatic VEPs in adults (p = 0.02). Variances of fractal dimension were higher from the abnormal than normal chromatic VEPs in children (p = 0.01). CONCLUSIONS: A useful analysis protocol to assess the fractal dimension of transformed VEPs has been developed.

Views and practices of Australian optometrists regarding driving for patients with central visual impairment.

BACKGROUND: Eye-care practitioners are often required to make recommendations regarding their patients' visual fitness for driving, including patients with visual impairment. This study aimed to understand the perspectives and management strategies adopted by optometrists regarding driving for their patients with central visual impairment. METHOD: Optometrists were invited to participate in an online survey (from April to June 2012). Items were designed to explore the views and practices adopted by optometrists regarding driving for patients with central visual impairment (visual acuity [VA] poorer than 6/12, normal visual fields, cognitive and physical health), including conditional driver's licences and bioptic telescopes. Closed- and open-ended questions were used. RESULTS: The response rate was 14 per cent (n = 300 valid responses were received). Most respondents (83 per cent) reported that they advised their patients with visual impairment to 'always' or 'sometimes' stop driving. Most were confident in interpreting the visual licensing standards (78 per cent) and advising on legal responsibilities concerning driving (99 per cent). Respondents were familiar with VA requirements for unconditional licensing (98 per cent); however, the median response VA of 6/15 as the poorest VA suggested for conditional licences differed from international practice and Australian medical guidelines released a month prior to the survey's launch. Few respondents reported prescribing bioptic telescopes (two per cent). While 97 per cent of respondents stated that they discussed conditional licences with their patients with visual impairment, relatively few (28 per cent) reported having completed conditional licence applications for such individuals in the previous year. Those who had completed applications were more experienced in years of practice (p = 0.02) and spent more time practising in rural locations (p = 0.03) than those who had not. CONCLUSION: The majority of Australian optometrists were receptive to the possibilities of driving options for individuals with central visual impairment, although management approaches varied with respect to conditional licensing.

Perceptions of Older People Regarding Their Vision and Incident Causation.

PURPOSE: It is widely known that visual impairment (VI) is a risk factor for falls, but patients or their eye care practitioners may not recognize other kinds of incidents as being problematic because of their vision. Consequently, older people with VI may have unmet needs for advice on how to carry out activities of daily living safely. Therefore, the purpose of this study was to understand whether older people with VI consider their vision as a causative factor of incidents they experience and their perceptions regarding the prevention of future incidents. If sample size permitted, a secondary aim was to evaluate whether quantitative findings supported their perceptions. METHODS: The study design was a prospective cohort study evaluating injurious and damaging incidents and related near misses using open questions in a written 2-weekly large-print diary with active follow-up over 8 weeks in older people (>60 years, n = 80) with and without VI. Baseline measures included habitual binocular visual acuity, contrast sensitivity, visual fields, 3-m walk test, and Short Form 12 physical and mental component scores. Participants' diary entries were coded. Factor analysis and binary logistic analysis were used to investigate whether baseline measures were predictive of incident occurrence. Risk and preventative factors identified were compared. RESULTS: Participants perceived that their vision was implicated in bump and fall incidents. Quantitative analysis indicated that contrast sensitivity and fitness were significant predictors of incident occurrence. Six vision-related and five non-vision-related causative factors were identified by participants as contributing factors. Participants frequently stated "don't know" when asked to identify solutions to prevent incident recurrence. CONCLUSIONS: Participants had unmet needs for advice in relation to incident prevention. It would be prudent for eye care practitioners to raise incident prevention in eye care consultations regardless of voiced patient concerns.

What is the appropriate age cut-off for cycloplegia in refraction?

PURPOSE: To investigate the age range for which cycloplegia provides additional information compared with non-cycloplegic refraction in teenagers and young adults. METHODS: Data for 1295 subjects (704 female; 591 male) from the Twins Eye Study in Tasmania (TEST) and the Brisbane Adolescent Twin Study (mean age: 19.65 ± 3.56, range: 13-26 years) were included. For all participants, cycloplegia was induced by instillation of either one drop of 1% cyclopentolate (13-14 years) or one drop of 1% tropicamide (15-26 years). Pre- and postcycloplegic refractive errors for both eyes were measured using a Humphrey-598 automated refractor and spherical equivalents of refractive error were calculated. Generalized Estimating Equations (GEE) were used to model the spherical equivalent refraction (SER) for each eye against age (by year) and axial length (in the given eye). RESULTS: The mean group difference between pre- and postcycloplegic SER (post minus pre) was 0.17 ± 0.52 D and 0.12 ± 0.51 D for the right and left eyes, respectively, indicating that postcycloplegic refraction was generally more hyperopic/less myopic. The mean difference between pre- and postcycloplegic SER decreased from 0.36 ± 0.41 D in the 13-year-olds to 0.06 ± 0.50 D in people aged 25 years. After adjusting for family-relatedness, the difference between pre- and postcycloplegia SER was significant in all age groups up until the age of 20 years. CONCLUSIONS: Non-cycloplegic autorefraction can result in group mean SER differences of greater myopia than cycloplegic autorefraction and occurs in teenagers (13-19 years of age), but not in adults 20-26 years. These data suggest that cycloplegia is not required in population estimates of refractive error for young adults once they reach approximately 20 years of age.

Differential effects of refractive blur on day and nighttime driving performance.

PURPOSE: To investigate the effect of different levels of refractive blur on real-world driving performance measured under day and nighttime conditions. METHODS: Participants included 12 visually normal, young adults (mean age = 25.8 ± 5.2 years) who drove an instrumented research vehicle around a 4 km closed road circuit with three different levels of binocular spherical refractive blur (+0.50 diopter sphere [DS], +1.00 DS, +2.00 DS) compared with a baseline condition. The subjects wore optimal spherocylinder correction and the additional blur lenses were mounted in modified full-field goggles; the order of testing of the blur conditions was randomized. Driving performance was assessed in two different sessions under day and nighttime conditions and included measures of road signs recognized, hazard detection and avoidance, gap detection, lane-keeping, sign recognition distance, speed, and time to complete the course. RESULTS: Refractive blur and time of day had significant effects on driving performance (P < 0.05), where increasing blur and nighttime driving reduced performance on all driving tasks except gap judgment and lane keeping. There was also a significant interaction between blur and time of day (P < 0.05), such that the effects of blur were exacerbated under nighttime driving conditions; performance differences were evident even for +0.50 DS blur relative to baseline for some measures. CONCLUSIONS: The effects of blur were greatest under nighttime conditions, even for levels of binocular refractive blur as low as +0.50 DS. These results emphasize the importance of accurate and up-to-date refractive correction of even low levels of refractive error when driving at night.

Assessment of the performance of automated focimeters in the measurement of single vision spectacle lenses.

BACKGROUND: The accuracy and precision of any instrument should not be taken for granted. While there is an international standard for checking focimeters, there is no report of any study on their performance. METHOD: A sample set of 51 focimeters (11 brands), were used to measure the spherical power of a set of lenses and the prismatic power of two lenses complying with ISO 9342-1:2005 and other calibrated prismatic lenses and the spherical power of some grey filters. RESULTS: The mean measured spherical power corresponded very closely with the calibrated values; however, the spread of results was substantial and 10 focimeters did not comply with ISO 8598:1996. The measurement of prism was much more accurate and precise and all the focimeters complied easily. With the grey filters, about one-third of the focimeters either showed erratic reading or an error with the equivalent of category 4 sunglasses. On the other hand, nine focimeters had stable and accurate reading on a filter with a luminous transmittance of 0.5 per cent. CONCLUSIONS: These results confirm that, in common with all other measurement instruments, there is a need to ensure that a focimeter is reading accurately and precisely over the range of refractive powers and luminous transmittances. The accurate and precise performance of an automated focimeter over its working life cannot be assumed. Checking before purchase with a set of calibrated lenses and some dark sunglass tints will indicate the suitability of a focimeter. Routine checking with the calibrated lenses will inform the users if a focimeter continues to indicate accurately.

Even moderate visual impairments degrade drivers' ability to see pedestrians at night.

PURPOSE: To determine the effect of moderate levels of refractive blur and simulated cataracts on nighttime pedestrian conspicuity in the presence and absence of headlamp glare. METHODS: The ability to recognize pedestrians at night was measured in 28 young adults (M = 27.6 years) under three visual conditions: normal vision, refractive blur, and simulated cataracts; mean acuity was 20/40 or better in all conditions. Pedestrian recognition distances were recorded while participants drove an instrumented vehicle along a closed road course at night. Pedestrians wore one of three clothing conditions and oncoming headlamps were present for 16 participants and absent for 12 participants. RESULTS: Simulated visual impairment and glare significantly reduced the frequency with which drivers recognized pedestrians and the distance at which the drivers first recognized them. Simulated cataracts were significantly more disruptive than blur even though photopic visual acuity levels were matched. With normal vision, drivers responded to pedestrians at 3.6- and 5.5-fold longer distances on average than for the blur or cataract conditions, respectively. Even in the presence of visual impairment and glare, pedestrians were recognized more often and at longer distances when they wore a "biological motion" reflective clothing configuration than when they wore a reflective vest or black clothing. CONCLUSIONS: Drivers' ability to recognize pedestrians at night is degraded by common visual impairments, even when the drivers' mean visual acuity meets licensing requirements. To maximize drivers' ability to see pedestrians, drivers should wear their optimum optical correction, and cataract surgery should be performed early enough to avoid potentially dangerous reductions in visual performance.

Using reflective clothing to enhance the conspicuity of bicyclists at night.

Bicycling at night is more dangerous than in the daytime and poor conspicuity is likely to be a contributing factor. The use of reflective markings on a pedestrian's major joints to facilitate the perception of biological motion has been shown to greatly enhance pedestrian conspicuity at night, but few corresponding data exist for bicyclists. Twelve younger and twelve older participants drove around a closed-road circuit at night and indicated when they first recognized a bicyclist who wore black clothing either alone, or together with a reflective bicycling vest, or a vest plus ankle and knee reflectors. The bicyclist pedalled in place on a bicycle that had either a static or flashing light, or no light on the handlebars. Bicyclist clothing significantly affected conspicuity; drivers responded to bicyclists wearing the vest plus ankle and knee reflectors at significantly longer distances than when the bicyclist wore the vest alone or black clothing without a vest. Older drivers responded to bicyclists less often and at shorter distances than younger drivers. The presence of a bicycle light, whether static or flashing, did not enhance the conspicuity of the bicyclist; this may result in bicyclists who use a bicycle light being overconfident of their own conspicuity at night. The implications of our findings are that ankle and knee markings are a simple and very effective approach for enhancing bicyclist conspicuity at night.

The Norfolk Island Eye Study (NIES): rationale, methodology and distribution of ocular biometry (biometry of the bounty).

AIM: To describe the recruitment, ophthalmic examination methods and distribution of ocular biometry of participants in the Norfolk Island Eye Study, who were individuals descended from the English Bounty mutineers and their Polynesian wives. METHODS: All 1,275 permanent residents of Norfolk Island aged over 15 years were invited to participate, including 602 individuals involved in a 2001 cardiovascular disease study. Participants completed a detailed questionnaire and underwent a comprehensive eye assessment including stereo disc and retinal photography, ocular coherence topography and conjunctival autofluorescence assessment. Additionally, blood or saliva was taken for DNA testing. RESULTS: 781 participants aged over 15 years were seen (54% female), comprising 61% of the permanent Island population. 343 people (43.9%) could trace their family history to the Pitcairn Islanders (Norfolk Island Pitcairn Pedigree). Mean anterior chamber depth was 3.32mm, mean axial length (AL) was 23.5mm, and mean central corneal thickness was 546 microns. There were no statistically significant differences in these characteristics between persons with and without Pitcairn Island ancestry. Mean intra-ocular pressure was lower in people with Pitcairn Island ancestry: 15.89mmHg compared to those without Pitcairn Island ancestry 16.49mmHg (P = .007). The mean keratometry value was lower in people with Pitcairn Island ancestry (43.22 vs. 43.52, P = .007). The corneas were flatter in people of Pitcairn ancestry but there was no corresponding difference in AL or refraction. CONCLUSION: Our study population is highly representative of the permanent population of Norfolk Island. Ocular biometry was similar to that of other white populations. Heritability estimates, linkage analysis and genome-wide studies will further elucidate the genetic determinants of chronic ocular diseases in this genetic isolate.

Effect of simulated visual impairment on nighttime driving performance.

PURPOSE: This study investigated the effects of simulated visual impairment on nighttime driving performance and pedestrian recognition under real-road conditions. METHODS: Closed road nighttime driving performance was measured for 20 young visually normal participants (M = 27.5 +/- 6.1 years) under three visual conditions: normal vision, simulated cataracts, and refractive blur that were incorporated in modified goggles. The visual acuity levels for the cataract and blur conditions were matched for each participant. Driving measures included sign recognition, avoidance of low contrast road hazards, time to complete the course, and lane keeping. Pedestrian recognition was measured for pedestrians wearing either black clothing or black clothing with retroreflective markings on the moveable joints to create the perception of biological motion ("biomotion"). RESULTS: Simulated visual impairment significantly reduced participants' ability to recognize road signs, avoid road hazards, and increased the time taken to complete the driving course (p < 0.05); the effect was greatest for the cataract condition, even though the cataract and blur conditions were matched for visual acuity. Although visual impairment also significantly reduced the ability to recognize the pedestrian wearing black clothing, the pedestrian wearing "biomotion" was seen 80% of the time. CONCLUSIONS: Driving performance under nighttime conditions was significantly degraded by modest visual impairment; these effects were greatest for the cataract condition. Pedestrian recognition was greatly enhanced by marking limb joints in the pattern of "biomotion," which was relatively robust to the effects of visual impairment.

The effect of presbyopic vision corrections on nighttime driving performance.

PURPOSE: To investigate the effect of various presbyopic vision corrections on nighttime driving performance on a closed-road driving circuit. METHODS: Participants were 11 presbyopes (mean age, 57.3+/-5.8 years), with a mean best sphere distance refractive error of R+0.23+/-1.53 DS and L+0.20+/-1.50 DS, whose only experience of wearing presbyopic vision correction was reading spectacles. The study involved a repeated-measures design by which a participant's nighttime driving performance was assessed on a closed-road circuit while wearing each of four power-matched vision corrections. These included single-vision distance lenses (SV), progressive-addition spectacle lenses (PAL), monovision contact lenses (MV), and multifocal contact lenses (MTF CL) worn in a randomized order. Measures included low-contrast road hazard detection and avoidance, road sign and near target recognition, lane-keeping, driving time, and legibility distance for street signs. Eye movement data (fixation duration and number of fixations) were also recorded. RESULTS: Street sign legibility distances were shorter when wearing MV and MTF CL than SV and PAL (P<0.001), and participants drove more slowly with MTF CL than with PALs (P=0.048). Wearing SV resulted in more errors (P<0.001) and in more (P=0.002) and longer (P<0.001) fixations when responding to near targets. Fixation duration was also longer when viewing distant signs with MTF CL than with PAL (P=0.031). CONCLUSIONS: Presbyopic vision corrections worn by naive, unadapted wearers affected nighttime driving. Overall, spectacle corrections (PAL and SV) performed well for distance driving tasks, but SV negatively affected viewing near dashboard targets. MTF CL resulted in the shortest legibility distance for street signs and longer fixation times.

Influence of presbyopic corrections on driving-related eye and head movements.

PURPOSE: To investigate whether wearing different presbyopic vision corrections alters the pattern of eye and head movements when viewing and responding to driving-related traffic scenes. METHODS: Participants included 20 presbyopes (mean age: 56.1 +/- 5.7 years) who had no experience of wearing presbyopic vision corrections, apart from single vision (SV) reading spectacles. Each participant wore five different vision corrections: distance SV lenses, progressive addition spectacle lenses (PAL), bifocal spectacle lenses (BIF), monovision (MV) and multifocal contact lenses (MTF CL). For each visual condition, participants were required to view videotape recordings of traffic scenes, track a reference vehicle, and identify a series of peripherally presented targets. Digital numerical display panels were also included as near visual stimuli (simulating the visual displays of a vehicle speedometer and radio). Eye and head movements were measured, and the accuracy of target recognition was also recorded. RESULTS: The path length of eye movements while viewing and responding to driving-related traffic scenes was significantly longer when wearing BIF and PAL than MV and MTF CL (both p < or = 0.013). The path length of head movements was greater with SV, BIF, and PAL than MV and MTF CL (all p < 0.001). Target recognition and brake response times were not significantly affected by vision correction, whereas target recognition was less accurate when the near stimulus was located at eccentricities inferiorly and to the left, rather than directly below the primary position of gaze (p = 0.008), regardless of vision correction. CONCLUSIONS: Different presbyopic vision corrections alter eye and head movement patterns. The longer path length of eye and head movements and greater number of saccades associated with the spectacle presbyopic corrections may affect some aspects of driving performance.

Effect of presbyopic vision corrections on perceptions of driving difficulty.

OBJECTIVES: As the population ages, more people will be wearing presbyopic vision corrections when driving. However, little is known about the impact of these vision corrections on driving performance. This study aimed to determine the subjective driving difficulties experienced when wearing a range of common presbyopic contact lens and spectacle corrections. METHODS: A questionnaire was developed and piloted that included a series of items regarding difficulties experienced while driving under daytime and nighttime conditions (rated on five-point and seven-point Likert scales). Participants included 255 presbyopic patients recruited through local optometry practices. Participants were categorized into five age-matched groups; including those wearing no vision correction for driving (n = 50), bifocal spectacles (n = 54), progressive spectacles (n = 50), monovision contact lenses (n = 53), and multifocal contact lenses (n = 48). RESULTS: Overall, ratings of satisfaction during daytime driving were relatively high for all correction types. However, multifocal contact lens wearers were significantly less satisfied with aspects of their vision during nighttime than daytime driving, particularly regarding disturbances from glare and haloes. Progressive spectacle lens wearers noticed more distortion of peripheral vision, whereas bifocal spectacle wearers reported more difficulties with tasks requiring changes of focus and those who wore no optical correction for driving reported problems with intermediate and near tasks. Overall, satisfaction was significantly higher for progressive spectacles than bifocal spectacles for driving. CONCLUSIONS: Subjective visual experiences of different presbyopic vision corrections when driving vary depending on the vision tasks and lighting level. Eye-care practitioners should be aware of the driving-related difficulties experienced with each vision correction type and the need to select corrective types that match the driving needs of their patients.

Seeing pedestrians at night: visual clutter does not mask biological motion.

Although placing reflective markers on pedestrians' major joints can make pedestrians more conspicuous to drivers at night, it has been suggested that this "biological motion" effect may be reduced when visual clutter is present. We tested whether extraneous points of light affected the ability of 12 younger and 12 older drivers to see pedestrians as they drove on a closed road at night. Pedestrians wore black clothing alone or with retroreflective markings in four different configurations. One pedestrian walked in place and was surrounded by clutter on half of the trials. Another was always surrounded by visual clutter but either walked in place or stood still. Clothing configuration, pedestrian motion, and driver age influenced conspicuity but clutter did not. The results confirm that even in the presence of visual clutter pedestrians wearing biological motion configurations are recognized more often and at greater distances than when they wear a reflective vest.

Weill-Marchesani syndrome and secondary glaucoma associated with ectopia lentis.

Weill-Marchesani syndrome (WMS) is a rare systemic connective tissue disorder with the systemic features of short stature, short and stubby hands and feet and stiff joints, especially in the hands. Occasionally, it is associated with heart defects and mental retardation. The main ocular features of WMS are microspherophakia (small and spherical crystalline lens), ectopia lentis (a displaced or malpositioned lens), severe myopia and glaucoma. Rare findings include asymmetric axial lengths associated with presenile vitreous liquefaction. A 14-year-old patient with WMS, who developed a secondary glaucoma and suffered visual loss from the ocular features of WMS, is described. The clinical findings and its successful management are also reported.