Refractive Blur Research Articles

Refractive blur’s influence on discomfort glare perception from white LED headlights at night

This study examined the effects of refractive blur on discomfort perception caused by peripheral glare from white LED passing (low)-beam headlights at night. The study compared two levels of binocular blur (+0.50 diopter [D] and +1.00D) against a baseline of optimal refractive correction. Thirty participants (mean age 21.3±1.6 years; range 20–24 years) simulating a driving position assessed discomfort from glare sources (headlights of oncoming vehicles) located at 40 and 20 m distances using the de Boer scale. The study found that, with a blur of +0.50D, discomfort glare from white LED headlights did not significantly differ from the baseline regarding de Boer scores. However, with a blur of +1.00D, de Boer scores significantly decreased, indicating increased discomfort glare compared with the baseline for all distances (P=0.004). These results suggest that refractive blur may contribute to an increased perception of discomfort glare during nighttime driving.

Development and Validation of a Novel Night-Time Hazard Visibility Test.

Night-time driving is dangerous, with increased crash rates, particularly involving vulnerable road users. A Night-Time Hazard Visibility Test (NHVT) was developed and validated by exploring the effects of refractive and cataract blur on performance. The NHVT comprised video clips of night-time roads from the driver's perspective, including different hazards (pedestrians, cyclists, and vehicles). Participants responded when they first recognized hazards requiring them to take evasive action to avoid a collision. In experiment 1, there were 16 young visually normal drivers (mean age = 22.3, standard deviation [SD] = 2.2 years) who completed 2 NHVT sets, viewed separately through best-correction and refractive blur (+1.00 diopter sphere [DS]). In experiment 2, a refined version of the NHVT was administered to an additional 16 young visually normal drivers (mean age = 21.1, SD = 1.2 years) with best-correction and cataract blur. The order of visual conditions and NHVT sets were counterbalanced. In experiment 1, refractive blur significantly reduced photopic visual acuity (VA) compared to best-corrected vision (+0.09 vs. -0.21 logMAR, P < 0.001) and delayed response times by 0.69 seconds (3.10 vs. 2.41 seconds, P < 0.001) compared to best-corrected vision. In experiment 2, cataract blur reduced VA compared to best-corrected vision (+0.03 vs. -0.17 logMAR, P < 0.001) and delayed response times by 0.63 seconds (2.92 vs. 2.29 seconds, P < 0.001). The NHVT was sensitive to refractive and cataract blur, providing preliminary support of its validity as a measure of night-time hazard visibility performance. The NHVT has potential as an off-road assessment of visibility for night driving and application for assessment of drivers with different refractive corrections and ocular diseases.

Low levels of refractive blur increase the risk of colour misperception of red train signals.

PurposeRed signals signify danger in a range of situations, including train operations. Importantly, misperception of a red signal as yellow can have serious safety implications. This study investigated the effects of lens blur on incorrect colour perception of red signals, which has been implicated in previous train crashes.MethodsParticipants included 15 young (26.6 ± 4.6 years) and 15 older (55.8 ± 3.1 years) visually normal adults. Red and yellow wayside train signals were simulated for two brightness levels (dim, bright) using a custom‐built projection system. The effect of blur (best‐corrected refraction [No Blur], +0.25 DS, +0.50 DS, +0.75 DS, +1.00 DS, +1.25 DS) on the number of incorrect colour perception responses of the signals was recorded. The order of conditions was randomised between participants.ResultsFor incorrect responses to the red signal, there were significant main effects of blur (p < 0.001) and signal brightness (p < 0.001) and a significant interaction between blur and brightness (p < 0.001). The effects of blur were greater for the dim compared to the bright signals, with significantly higher colour misperceptions for the dim signal for +0.50 DS blur and higher, compared with No Blur. Colour misperceptions of the yellow signals were low compared with that of the red signals, with only +1.25 DS blur resulting in a significantly higher number of incorrect responses than No Blur (p < 0.001). There were no effects of age for the red or yellow colour misperceptions (p > 0.19).ConclusionsLow levels of blur (+0.50 DS to +1.25 DS) resulted in a significant misperception of the red signals as orange‐yellow, particularly for dim signals. The findings have implications for vision testing and refractive correction of train drivers to minimise the possibility of colour misperception of red train signals.

Refractive blur affects judgement of pedestrian walking direction at night.

Many individuals drive with uncorrected refractive errors, which has implications for night driving, where poor visibility contributes to the increased crash risk relative to daytime. This study explored how small amounts of refractive blur affects the judgment of the walking direction of night-time pedestrians and whether different types of retro-reflective clothing influence this effect. Judgement of the walking direction of night-time pedestrians was investigated for 20 young participants with normal vision (mean age, 21.8±1.6years) for two levels of binocular blur (+0.50DS, +1.00DS) compared to baseline (best-corrected refractive correction). Participants seated in a stationary car with low beam headlamps observed a pedestrian wearing three clothing conditions: retro-reflective vest (1) and retro-reflective biomotion clothing (incorporating thin (2) or thick (3) retro-reflective strips), who walked across the road in three directions (straight across, away or towards the car). The order of conditions was randomised among participants. Participants reported the perceived pedestrian walking direction and how confident they rated their response. Outcome measures included the proportion of correct responses (response accuracy) and confidence ratings. Blur had a significant effect on accuracy in judging pedestrian walking direction; accuracy decreased significantly with increasing blur (p<0.001), with all blur levels being significantly different from one another. The effect of pedestrian clothing was also significant (p < 0.001); direction judgements were least accurate for vest, followed by both thin and thick biomotion, where accuracy judgements were similar. There was also a significant interaction between blur and clothing (p < 0.05). Similar trends were found for confidence ratings across the blur and clothing conditions. Greater confidence was significantly associated with increased response accuracy for the biomotion clothing, but not the vest. Findings highlight that even small amounts of blur (+0.50DS), that do not reduce visual acuity below the legal driving limits, reduce the ability to accurately judge pedestrian walking direction at night. Retro-reflective clothing in a biomotion configuration facilitated the highest accuracy and confidence in judgment of pedestrian walking direction, for both thin and thick strips compared to vest, for all blur levels.

The effects of auditory satellite navigation instructions and visual blur on road hazard perception

The distracting effects of mobile telephone use while driving are well known, however the effects of other sources of distraction, such as auditory navigation devices, are less well understood. Whether the effects of auditory distraction might interact with other sensory impairments, such as vision impairment, is of interest given that visual impairment is relatively common within the population, particularly as a result of uncorrected refractive error. In this experiment, 20 current drivers (mean age of 29.4 ± 3.2 years), binocularly viewed video recordings of traffic scenes presented as part of the Hazard Perception Test and responded to potential hazards within the traffic scenes. Half of the presented scenes included auditory navigation instructions as an auditory distractor. Additionally, some of the scenes were viewed through optical lenses to induce different levels of refractive blur (+0.50 DS, +1.00 DS and +2.00 DS). Hazard perception response times increased significantly (p < 0.05) with increasing blur. Participants were significantly slower in reacting to hazards for the +1.00 DS and +2.00 DS blur conditions compared to the control condition (with no blur). There was also a significant increase in response times to hazards in the presence of the auditory navigation instructions. The combined effect of blur and auditory instructions was additive, with the worst performance being in the presence of both blur and auditory instructions. These results suggest that the delivery of auditory navigation guidance for those with visual impairments, such as blur, which are relatively common in the population, should be further investigated.

Contrast Sensitivity Is a Significant Predictor of Performance in Rifle Shooting for Athletes With Vision Impairment.

Purpose: In order to develop an evidence-based, sport-specific minimum impairment criteria (MIC) for the sport of vision-impaired (VI) shooting, this study aimed to determine the relative influence of losses in visual acuity (VA) and contrast sensitivity (CS) on shooting performance. Presently, VA but not CS is used to determine eligibility to compete in VI shooting.Methods: Elite able-sighted athletes (n = 27) shot under standard conditions with their habitual vision, and with their vision impaired by the use of simulation spectacles (filters which reduce both VA and CS) and refractive blur (lenses which reduce VA with less effect on CS). Habitual shooting scores were used to establish a cut-off in order to determine when shooting performance was ‘below expected’ in the presence of vision impairment. Logistic regression and decision tree analyses were then used to assess the relationship between visual function and shooting performance.Results: Mild reductions in VA and/or CS did not alter shooting performance, with greater reductions required for shooting performance to fall below habitual levels (below 87% of normalized performance). Stepwise logistic regression selected CS as the most significant predictor of shooting performance, with VA subsequently improving the validity of the model. In an unconstrained decision tree analysis, CS was selected as the sole criterion (80%) for predicting ‘below expected’ shooting score.Conclusion: Shooting performance is better predicted by losses in CS than by VA. Given that it is not presently tested during classification, the results suggest that CS is an important measure to include in testing for the classification of vision impairment for athletes competing in VI shooting.

Effects of Light Scatter and Blur on Low-Contrast Vision and Disk Halo Size.

To investigate the individual effects of forward light scatter (FLS) and refractive blur on low-contrast vision and the size of the disk halo produced in response to an external glare source. Monocular disk halo radius, high- and low-contrast distance visual acuity (HCVA, LCVA), and contrast sensitivity (CS) were determined in 25 eyes of 25 healthy subjects under normal, FLS, and blur conditions. FLS was induced using the filter Black ProMist 2 to simulate an early cataract. Blur was induced using a +1.00 diopter lens to simulate an uncorrected refractive error. Similar significant mean increases in halo radius were observed for the FLS (0.32 ± 0.10 log arc min; P < .0001) and refractive blur (0.40 ± 0.18 log arc min; P < .0001). Under induced blur, 3 lines of HCVA (0.32 ± 0.15 logMAR; P < .0001) and 4 lines of LCVA (0.39 ± 0.16 logMAR; P < .0001) were lost. FLS had a minimal (but significant) effect on HCVA, but worsened mean LCVA by more than 1 line (0.13 ± 0.10 logMAR; P < .0001). Similar significant mean CS reductions of 0.17 ± 0.12 (P < .0001) and 0.14 ± 0.12 log units (P < .0001) were produced in response to FLS and refractive blur, respectively (approximately 1 triplet). Forward light scatter and refractive blur contributed to an increased size of the disk halo produced by a glare source in similar proportion. Although defocus blur has a substantial effect on LCVA, a loss of more than 1 line of LCVA after best refractive correction would be indicative of FLS.

Intermittent exotropia

In this invited commentary, the authors discuss whether the use of minus lenses to aid control of intermittent exotropia has an alternative method of action. Conventional theory suggests that the lenses induce accommodation and therefore accommodative convergence to reduce the angle of deviation. We discuss evidence which suggests that convergence is induced to control the primary deviation and that the minus lenses allow this control by correcting refractive blur caused by additional vergence accommodation.

Distinctive features of microsaccades in amblyopia and refractive blur

Miniature eye movements like microsaccades shift the image on the fovea and counteract visual fading that occurs from neural adaptation. They are also thought to serve as an optimal sampling strategy while viewing complex visual scenes. The goal of the study was to assess the influence of (a) simple visual blur induced by uncorrected refractive error (RE) and (b) amblyopia on microsaccades.

Effects of Different Levels of Refractive Blur on Nighttime Pedestrian Visibility.

The aim of this study was to systematically investigate the effect of different levels of refractive blur and driver age on nighttime pedestrian recognition and determine whether clothing that has been shown to improve pedestrian conspicuity is robust to the effects of blur. Nighttime pedestrian recognition was measured for 24 visually normal participants (12 younger mean = 24.9 ± 4.5 years and 12 older adults mean = 77.6 ± 5.7 years) for three levels of binocular blur (+0.50 diopter [D], +1.00 D, +2.00 D) compared with baseline (optimal refractive correction). Pedestrians walked in place on a closed road circuit and wore one of three clothing conditions: everyday clothing, a retro-reflective vest, and retro-reflective tape positioned on the extremities in a configuration that conveyed biological motion (known as "biomotion"); the order of conditions was randomized among participants. Pedestrian recognition distances were recorded for each blur and pedestrian clothing combination while participants drove an instrumented vehicle around a closed road course. The recognition distances for pedestrians were significantly reduced (P < 0.05) by all levels of blur compared with baseline. Pedestrians wearing biomotion clothing were recognized at significantly longer distances than for the other clothing configurations in all blur conditions. However, these effects were smaller for the older adults, who had much shorter recognition distances for all conditions tested. In summary, even small amounts of blur had a significant detrimental effect on nighttime pedestrian recognition. Biomotion retro-reflective clothing was effective, even under moderately degraded visibility conditions, for both young and older drivers.

The effects of simulated vision impairments on the cone of gaze.

Detecting the gaze direction of others is critical for many social interactions. We explored factors that may make the perception of mutual gaze more difficult, including the degradation of the stimulus and simulated vision impairment. To what extent do these factors affect the complex assessment of mutual gaze? Using an interactive virtual head whose eye direction could be manipulated by the subject, we conducted two experiments to assess the effects of simulated vision impairments on mutual gaze. Healthy subjects had to demarcate the center and the edges of the cone of gaze-that is, the range of gaze directions that are accepted for mutual gaze. When vision was impaired by adding a semitransparent white contrast reduction mask to the display (Exp. 1), judgments became more variable and more influenced by the head direction (indicative of a compensation strategy). When refractive blur was added (Exp. 1), the gaze cone shrank from 12.9° (no blur) to 11.3° (3-diopter lens), which cannot be explained by a low-level process but might reflect a tightening of the criterion for mutual gaze as a response to the increased uncertainty. However, the overall effects of the impairments were relatively modest. Elderly subjects (Exp. 2) produced more variability but did not differ qualitatively from the younger subjects. In the face of artificial vision impairments, compensation mechanisms and criterion changes allow us to perform better in mutual gaze perception than would be predicted by a simple extrapolation from the losses in basic visual acuity and contrast sensitivity.

Stepping accuracy and visuomotor control among older adults: effect of target contrast and refractive blur.

Older adults have increased visual impairment, including refractive blur from presbyopic multifocal spectacle corrections, and are less able to extract visual information from the environment to plan and execute appropriate stepping actions; these factors may collectively contribute to their higher risk of falls. The aim of this study was to examine the effect of refractive blur and target visibility on the stepping accuracy and visuomotor stepping strategies of older adults during a precision stepping task. Ten healthy, visually normal older adults (mean age 69.4±5.2years) walked up and down a 20m indoor corridor stepping onto selected high and low contrast targets while viewing under three visual conditions: best-corrected vision, +2.00 DS and +3.00 DS blur; the order of blur conditions was randomised between participants. Stepping accuracy and gaze behaviours were recorded using an eyetracker and a secondary hand-held camera. Older adults made significantly more stepping errors with increasing levels of blur, particularly exhibiting under-stepping (stepping more posteriorly) onto the targets (p<0.05), while visuomotor stepping strategies did not significantly alter. Stepping errors were also significantly greater for the low compared to the high contrast targets and differences in visuomotor stepping strategies were found, including increased duration of gaze and increased interval between gaze onset and initiation of the leg swing when stepping onto the low contrast targets. These findings highlight that stepping accuracy is reduced for low visibility targets, and for high levels of refractive blur at levels typically present in multifocal spectacle corrections, despite significant changes in some of the visuomotor stepping strategies. These findings highlight the importance of maximising the contrast of objects in the environment, and may help explain why older adults wearing multifocal spectacle corrections exhibit an increased risk of falling.

Effect of Induced Refractive Error and Nuclear Sclerotic Cataracts on Ishihara Colour Plate Testing

Objective: To determine the effect of induced refractive blur and nuclear sclerotic (NS) cataracts on Ishihara colour plate (ICP) scores. Design: Prospective evaluation of a diagnostic test Participants: Patients who presented to Hotel Dieu Hospital Eye clinic between January and March 2010 with either a lone diagnosis of nuclear sclerotic cataracts, or with no identified ocular disease with complete examination. Methods: Patients were divided into two groups: those having no identified ocular disease on examination, and those with a lone diagnosis of NS cataracts. The first group was refractively blurred with +3D, +6D, +9D and +12D lenses. Best corrected visual acuity (BCVA) at near and ICP scores was obtained from both groups. Results: There were 20 patients in each group. BCVA at near and ICP values declined with increasing amounts of plus lenses as expected. With the application of the +3D, +6D, +9D, and +12D lenses, the association between ICP scores and BCVA at near decreased (-0.845, -0.678, -0.374, and -0.363 respectively). There was little clinical decline in absolute ICP scores until lenses of +9D (mean BCVA at near=20/400) or greater were applied. The correlation between ICP scores and BCVA at near declines due to NS cataracts was -0.53. Conclusion: ICP testing is valid to BCVA at near of 20/100 when the acuity decline is due solely to NS cataracts. Further study is required to determine whether or not severe vision loss due to NS cataracts affects ICP scores and at what visual acuity.

Differential Effects of Refractive Blur on Day and Nighttime Driving Performance

To investigate the effect of different levels of refractive blur on real-world driving performance measured under day and nighttime conditions. 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. 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. 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.

Even Moderate Visual Impairments Degrade Drivers' Ability to See Pedestrians at Night

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. 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. 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. 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.

Psychophysical measures of visual acuity in autism spectrum conditions

Previously reported superior visual acuity (VA) in autism spectrum conditions (ASC) may have resulted from methodological settings used ( Ashwin, Ashwin, Rhydderch, Howells, & Baron-Cohen, 2009). The current study re-tested whether participants with ( N = 20) and without ( N = 20) ASC differ on psychophysical measures of VA. Participants’ vision was corrected before acuity measurement, minimising refractive blur. VA was assessed with an ETDRS chart as well as the Freiburg Visual Acuity and Contrast Test (FrACT). FrACT testing was undertaken at 4 m (avoiding limitations of pixel-size), using 36 trials (avoiding fatigue). Best corrected VA was significantly better than the initial habitual acuity in both groups, but adults with and without ASC did not differ on ETDRS or FrACT binocular VA. Future research should examine at which level of visual processing sensory differences emerge.

Dichoptic Suppression of mfVEP Amplitude: Effect of Retinal Eccentricity and Simulated Unilateral Visual Impairment

To investigate the effect of retinal eccentricity on the phenomenon of dichoptic suppression of the mfVEP amplitude and to examine the relationship between the degree of simulated unilateral visual impairment and the possible release of dichoptic suppression in the contralateral eye. Eight subjects with corrected visual acuity (VAc) >6/6 and stereoacuity >60 sec arc underwent monocular and dichoptic pattern-pulse mfVEP. Dichoptic stimulation was repeated with refractively induced blur of one eye with +4-D and +6-D lenses above distance correction. Dichoptic recording resulted in significant reduction of averaged mfVEP amplitude (19.8% ± 4.9%, paired t-test, P = 0.00003). The magnitude of suppression, while statistically significant at all eccentricities, was significantly larger in the central part of the visual field and diminished toward the periphery. Refractive blur, used to simulate visual impairment produced variable degrees of amplitude reduction in the blurred eye and resulted in amplitude increases in the contralateral eye. There was a highly significant correlation between the magnitude of amplitude reduction in the blurred eye and increase in amplitude (i.e., release of dichoptic suppression) in the contralateral eye (r = 0.91, P < 0.0001). The study demonstrated that dichoptic stimulation results in eccentricity-dependent suppression of mfVEP amplitude. Factors affecting visual performance of one eye (monocular blur) promote the release of dichoptic suppression in the fellow (unaffected) eye. This phenomenon leads to an increase in intereye asymmetry and therefore may improve early detection of ocular diseases, especially monocular pathologic processes.

Effect of Simulated Visual Impairment on Nighttime Driving Performance

This study investigated the effects of simulated visual impairment on nighttime driving performance and pedestrian recognition under real-road conditions. 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"). 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. 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 resilience of natural interceptive actions to refractive blur

The impact of refractive visual blur on interceptive skill was examined for a series of highly-demanding striking tasks. Ten skilled cricket batsmen were required to intercept balls projected by either a ball projection-machine (medium-pace only) or cricket bowlers (two velocities; medium-pace and fast-pace) under each of four systematically varied visual conditions. Contact lenses were fitted to simulate increments in refractive blur (habitual, +1.00, +2.00, +3.00 D), with changes in interceptive performance evaluated on three concurrent measures of performance relevant to cricket batting (quality of bat–ball contact, forcefulness of bat-swing, and likelihood of dismissal). For the projection-machine condition, results replicate those reported previously ( Mann, Ho, De Souza, Watson, & Taylor, 2007) with blur needing to reach +3.00 D before any significant decreases in performance were evident, a finding further replicated when facing bowlers of comparable velocity. The influence of blur on interception was found to interact with ball-velocity, with the increased temporal demands of fast-paced trials resulting in decreased performance becoming evident at a lower level of blur (+2.00 D). The findings demonstrate that even when presented with a situation replicating highly-demanding performance conditions, substantial degradation of visual clarity is possible before acuity is a limiting factor for interceptive performance.

Tilted disc syndrome may mimic false visual field deterioration

Tilted disc syndrome is a congenital anomaly of the eye characterized by mostly upper temporal visual field defects. The aim of the present study was to evaluate the effect of gradual myopic correction in the improvement of visual field defects associated with tilted disc syndrome. The visual field was examined in 38 eyes of 24 patients using standard Goldmann perimetry. The isoptres IV-4e, I-4e, I-3e and I-2e were plotted. The defective isoptres were tested again with gradually increasing myopic correction until no further change was noted. The most common type of defect was a relative upper temporal defect (19 eyes). Temporal relative defects were found in five eyes, upper altitudinal field defects in six eyes, an enlarged blind spot in four eyes, and an inferior field defect in one eye. The visual field defect partly or totally disappeared with increased myopic correction in 18 (50%) eyes. The mean improvement was 17.0 +/- 6.2 degrees and the mean additional myopic correction was 3.1 +/- 1.5 D. Even a small change in near correction during visual field examination may imply worsened or improved visual field defects in tilted disc syndrome. To prevent a false interpretation of field deterioration in a patient with tilted disc syndrome and glaucoma, visual field assessment should include examination with the myopic correction that provides the maximal improvement of the defective visual field.