Does correcting astigmatism with toric lenses improve driving performance?

TFOS Lifestyle: Impact of contact lenses on the ocular surface

Several lifestyle choices made by contact lens wearers can have adverse consequences on ocular health. These include being non-adherent to contact lens care, sleeping in lenses, ill-advised purchasing options, not seeing an eyecare professional for regular aftercare visits, wearing lenses when feeling unwell, wearing lenses too soon after various forms of ophthalmic surgery, and wearing lenses when engaged in risky behaviors (e.g., when using tobacco, alcohol or recreational drugs). Those with a pre-existing compromised ocular surface may find that contact lens wear exacerbates ocular disease morbidity. Conversely, contact lenses may have various therapeutic benefits. The coronavirus disease-2019 (COVID-19) pandemic impinged upon the lifestyle of contact lens wearers, introducing challenges such as mask-associated dry eye, contact lens discomfort with increased use of digital devices, inadvertent exposure to hand sanitizers, and reduced use of lenses. Wearing contact lenses in challenging environments, such as in the presence of dust and noxious chemicals, or where there is the possibility of ocular trauma (e.g., sport or working with tools) can be problematic, although in some instances lenses can be protective. Contact lenses can be worn for sport, theatre, at high altitude, driving at night, in the military and in space, and special considerations are required when prescribing in such situations to ensure successful outcomes. A systematic review and meta-analysis, incorporated within the review, identified that the influence of lifestyle factors on soft contact lens dropout remains poorly understood, and is an area in need of further research. Overall, this report investigated lifestyle-related choices made by clinicians and contact lens wearers and discovered that when appropriate lifestyle choices are made, contact lens wear can enhance the quality of life of wearers.

Does offering only the spherical contact lens trial to the low astigmats mislead the practitioners?

AIM

To compare the visual acuity (VA), comfort, and patient preference in a soft toric contact lens (TCL) versus soft spherical contact lens (SCL) in low astigmatic subjects during the contact lens (CL) trial.

METHODS

This subject-masked, block randomized, 2×2 crossover study recruited 40 neophyte subjects (80 eyes) aged 18 to 33y with astigmatism in the range of 0.75-1.25 D with or without spherical power from -6.00 D to +6.00 D. The participants were scheduled for two days CL trial and were fitted with the best-fit SCL and TCL. After 4h of wear, they were assessed objectively for high contrast VA and subjective vision, comfort, and preference.

RESULTS

The responses of 36 subjects (response rate 90%) with a mean age of 23.02±2.97y (range 18 to 33y) were analyzed. One-line improvement of monocular VA in the logMAR chart was reported to TCL as compared to SCL (-0.044±0.06 vs 0.04±0.03 logMAR, P=0.01) but the binocular vision remained similar (-0.12±0.07 vs -0.14±0.04 logMAR, P=0.38). Subjects felt a noticeable difference in clarity when shifted to TCL as compared to the SCL. The satisfaction with vision (vision quality) was significantly better with TCL (P=0.03). The fatigue with TCL was graded less at 2.5±0.6, compared to SCL at 4.6±1.3 (P=0.04). Thirty-three participants (91.6%) preferred to use contact lens of which 26 participants (79%) preferred TCL.

CONCLUSION

The findings suggest that VA and comfort are better with TCL as compared to SCL which is only observed if the patient was offered both offering SCL with spherical equivalent power alone as the first option can mislead the practitioner; TCL trial should be the first choice of the lens in low-to-moderate astigmatism.

Increased visual and cognitive demands emphasize the importance of meeting visual needs at all distances while driving

Having an optimal quality of vision as well as adequate cognitive capacities is known to be essential for driving safety. However, the interaction between vision and cognitive mechanisms while driving remains unclear. We hypothesized that, in a context of high cognitive load, reduced visual acuity would have a negative impact on driving behavior, even when the acuity corresponds to the legal threshold for obtaining a driving license in Canada, and that the impact observed on driving performance would be greater with the increase in the threshold of degradation of visual acuity. In order to investigate this relationship, we examined driving behavior in a driving simulator under optimal and reduced vision conditions through two scenarios involving different levels of cognitive demand. These were: 1. a simple rural driving scenario with some pre-programmed events and 2. a highway driving scenario accompanied by a concurrent task involving the use of a navigation device. Two groups of visual quality degradation (lower/ higher) were evaluated according to their driving behavior. The results support the hypothesis: A dual task effect was indeed observed provoking less stable driving behavior, but in addition to this, by statistically controlling the impact of cognitive load, the effect of visual load emerged in this dual task context. These results support the idea that visual quality degradation impacts driving behavior when combined with a high mental workload driving environment while specifying that this impact is not present in the context of low cognitive load driving condition.

Non-Orthogonal Refractive Lenses for Non-Orthogonal Astigmatic Eyes

Purpose: To present a novel design method for non-orthogonal lenses to reduce the problem of residual astigmatism in non-orthogonal, astigmatic eyes Methods: A method to create spectacle trial lenses with non-orthogonal power axes was developed based on a novel optimised light ray-tracing algorithm rather than conventional lens design methods which could not fully eliminate spherical aberration. Using this method, three sets of refraction trial lenses were made with the angles between power axes of each set controlled at 80°, 70° and 60°, respectively. Within each set, the cylindrical power varied from -1.00 D to -6.00 D in 1.00 D steps in addition to a -0.50 D lens. Computer-based numerical simulation of the lenses optical performance was carried out to apply orthogonal and non-orthogonal lenses on simulated astigmatic eyes. Subsequently, three clinical trial cases were investigated. Results: Computer-simulated optical performance of non-orthogonal lenses showed the ability to achieve high performance in correcting non-orthogonal astigmatism. Subsequently, three patients with irregular astigmatism were refracted with the non-orthogonal lens sets, and clinically observed improvement at least two lines in the LogMAR chart was achieved in all three cases, compared with correction with orthogonal lenses, along with subjective improvement in image quality. Conclusions: Non-orthogonal astigmatism, which is commonly ignored by current eye prescription systems, is taken into account in this study in the design of spectacle and soft contact lenses. The new approach considers the possible non-orthogonal positions of the eye's two optical power meridians and appears to be better able to correct the vision of irregular astigmatic eyes and significantly reduce residual astigmatism.

Agreement and repeatability of objective systems for assessment of the tear film

PURPOSE

To assess the agreement and repeatability of two objective systems for measuring the tear film stability.

METHODS

Retrospective analysis of the tear film stability of 99 healthy right eyes measured with a videokeratoscope (VK) and the Optical Quality Analysis System (OQAS, Visiometrics). Two consecutive measures were taken with both systems, with an interval of 10 min between them. Variables included in the study were first and mean non-invasive break-up times (NIBUT and MNIBUT) measured with VK, and mean and standard deviation of the optical scattering index (OSIm and OSIsd) measured with OQAS. The agreement and repeatability of grading scales provided by both devices were also evaluated using the Cohen's k with quadratic weights. The Ocular Surface Disease index (OSDI) questionnaire was also passed out to all subjects. Correlations and associations between subjective and objective metrics were analyzed.

RESULTS

Significant differences were found between consecutive measurements of NIBUT (p = 0.04) and MNIBUT (p = 0.01), but not for OSIm (p = 0.11) and OSIsd (p = 0.50). Grading scales resulted in fair (k = 0.20) or poor agreement (k = 0.04) between systems depending if the first or second trial was considered. The repeatability of the grading scale was good for OQAS (k = 0.59) and fair for VK (k = 0.37). No significant correlations or associations were found between OSDI and any of the metrics obtained with both devices (p ≥ 0.36).

CONCLUSIONS

The two devices evaluated cannot be used interchangeably for the assessment of tear film stability. Good intrasession repeatability was obtained for tear film grading of the OQAS whereas it was fair for VK.

Ocular residual and corneal astigmatism in a clinical population of high school students

Purpose

Total refractive astigmatism is usually the first consideration that guides the selection of contact lens type (e.g., spherical or toric), while the ocular source of the astigmatism is a second, but more important consideration, for the final clinical decision. This study was conducted to provide detailed data on this topic by evaluating astigmatic components in Chinese adolescents.

Methods

Participants were recruited from healthy high school students undergoing an annual ocular examination at a local hospital. Total astigmatism (TA), corneal astigmatism (CA), and ocular residual astigmatism (ORA) were determined by a Hartmann-Shack wavefront analyzer system (KR-1W, Topcon) with the natural pupil. The axis relationship between CA and ORA was placed into three categories: on-axis, defined as an axis with a difference of 0 ± 10°; opposite-axis, a difference of 90 ± 10°; and the rest defined as oblique-axis.

Results

The study consisted of 1,466 students (57.84% girls, age: 16.49 ± 1.05 years). ORA was present in 83.97%, 66.64%, and 45.23% of participants, according to the various criteria for astigmatism (≥ 0.50 D, ≥ 0.75 D, and ≥ 1.00 D, respectively). While with-the-rule was the most common axis orientation for both TA (76.28%) and CA (89.94%), against-the-rule predominated in ORA (93.82%; χ² = 1688.544, p < 0.001). Opposite-axis was the major type of axis difference (90.96%) of clinical significance (i.e., ≥ 1.00 D) between CA and ORA, which also prevailed in all levels of TA (range: 56.25–82.26%).

Conclusions

ORA is common in high school students and usually demonstrates a compensation relationship with CA, which should be taken into consideration when determining the design of contact lenses to correct refractive error.

Can Youth with Autism Spectrum Disorder Use Virtual Reality Driving Simulation Training to Evaluate and Improve Driving Performance? An Exploratory Study

Investigate how novice drivers with autism spectrum disorder (ASD) differ from experienced drivers and whether virtual reality driving simulation training (VRDST) improves ASD driving performance. 51 novice ASD drivers (mean age 17.96 years, 78% male) were randomized to routine training (RT) or one of three types of VRDST (8-12 sessions). All participants followed DMV behind-the-wheel training guidelines for earning a driver's license. Participants were assessed pre- and post-training for driving-specific executive function (EF) abilities and tactical driving skills. ASD drivers showed worse baseline EF and driving skills than experienced drivers. At post-assessment, VRDST significantly improved driving and EF performance over RT. This study demonstrated feasibility and potential efficacy of VRDST for novice ASD drivers.

Driving Performance of Residents after Six Consecutive Overnight Work Shifts

Background

Residency training requires work in clinical settings for extended periods of time, resulting in altered sleep patterns, sleep deprivation, and potentially deleterious effects on safe performance of daily activities, including driving a motor vehicle.

Methods

Twenty-nine anesthesiology resident physicians in postgraduate year 2 to 4 drove for 55 min in the Virginia Driving Safety Laboratory using the Driver Guidance System (MBFARR, LLC, USA). Two driving simulator sessions were conducted, one experimental session immediately after the final shift of six consecutive night shifts and one control session at the beginning of a normal day shift (not after call). Both sessions were conducted at 8:00 am. Psychomotor vigilance task testing was employed to evaluate reaction time and lapses in attention.

Results

After six consecutive night shifts, residents experienced significantly impaired control of all the driving variables including speed, lane position, throttle, and steering. They were also more likely to be involved in collisions. After six consecutive night shifts, residents had a significant increase in reaction times (281.1 vs. 298.5 ms; P = 0.001) and had a significant increase in the number of both minor (0.85 vs. 1.88; P = 0.01) and major lapses (0.00 vs. 0.31; P = 0.008) in attention.

Conclusions

Resident physicians have greater difficulty controlling speed and driving performance in the driving simulator after six consecutive night shifts. Reaction times are also increased with emphasis on increases in minor and major lapses in attention after six consecutive night shifts.