The effect of pupil dilation with tropicamide on vision and driving simulator performance

[On refraction shift after trabeculectomy]

PURPOSE

To determine the factors affecting the shift of refraction after trabeculectomy.

MATERIAL AND METHODS

The study included 42 patients who were examined prior to trabeculectomy and at the following timepoints: 1 week, 1 month and 3 months after surgery. Examination included tonometry with assessment of corneal biomechanical properties, keratorefractometry with vector analysis, and biometry. The obtained data was processed for regression analysis and to find the possible correlations.

RESULTS

All significant correlations between the measured parameters only occur on week 1. Postoperative spherical component of refraction (sphere) correlates negatively both with preoperative axial length (AL) and anterior chamber depth (ACD) (r=-0.699 and r=-0.458, p<0.05) and postoperative AL and ACD (r= -0.767 and r= -0.415, p<0.011). Dependence of sphere on AL is also expressed as a regression model. The magnitude of AL change depends on the magnitude of intraocular pressure (IOP) change (r=0.729, p<0.0001) and correlates negatively with postoperative IOP (r=-0.454, p=0.009) and baseline corneal hysteresis (CH; r= -0.482, p=0.009). Dependence of AL on IOP is also expressed as a regression model. The magnitudes of sphere and cylinder shifts correlate negatively with each other (r=-0.416, p=0.038). Keratometry reveals that the overall cylinder value correlates with the corneal cylinder, and so do the magnitudes of their shifts (r=0.589 and r=0.574, p<0.0001). Dependence of corneal hysteresis on IOP is expressed as a regression model; however, neither tonometric nor biomechanical corneal properties correlate with refraction.

CONCLUSIONS

Sphere correlates negatively with AL and ACD. In turn, AL is related to the reduction in IOP. This dependence is likely the most important one for the refraction shift after trabeculectomy. No correlations were found for the change of astigmatism.

[Impact of mydriatic eyedrops on distance visual acuity in patients with exudative age-related macular degeneration]

PURPOSE

To demonstrate a decrease in distance visual acuity (VA) following instillation of mydriatic eyedrops in eyes with exudative age-related macular degeneration (AMD).

MATERIALS AND METHODS

A prospective assessment in clinical practice was conducted in our ophthalmology department at the University Hospital of Tours from 7/19/2018 to 8/29/2018. Distance (ETDRS) and near (Parinaud) VA were assessed before and after instilling one drop each of tropicamide 0.5% and phenylephrine 10% in the 40 included eyes with exudative AMD.

RESULTS

The mean difference in distance VA before and after pupillary dilation (PD) was 0.06 LogMAR (SD=0.14) (P<0.01), i.e. -3.05 letters read (SD=7.52) on the ETDRS chart (P=0.01). For near VA, the mean difference was 0.16 LogMAR (SD=0.16) (P<0.001), i.e. -1.58 paragraphs read (SD=1.63) on the Parinaud chart (P<0.001).

DISCUSSION

The absence of a clinically significant loss in post-dilation distance VA for exudative AMD could be explained by negligible glare coming from the ETDRS chart, milder photophobia, low pre-dilation VA's and a balance between higher order optical aberrations and diffraction. The opposite result for near VA could essentially be explained by greater glare induced by the light illuminating the Parinaud chart.

CONCLUSION

Our primary goal was not achieved. A study presuming the absence of a clinically significant decrease in post-dilation distance VA would be necessary to consider directly measuring post-dilation VA in eyes with exudative AMD in our daily practice.

Individual Differences in the Post-Illumination Pupil Response to Blue Light: Assessment without Mydriatics

Melanopsin-containing retinal ganglion cells play an important role in the non-image forming effects of light, through their direct projections on brain circuits involved in circadian rhythms, mood and alertness. Individual differences in the functionality of the melanopsin-signaling circuitry can be reliably quantified using the maximum post-illumination pupil response (PIPR) after blue light. Previous protocols for acquiring PIPR relied on the use of mydriatics to dilate the light-exposed eye. However, pharmacological pupil dilation is uncomfortable for the participants and requires ophthalmological expertise. Hence, we here investigated whether an individual's maximum PIPR can be validly obtained in a protocol that does not use mydriatics but rather increases the intensity of the light stimulus. In 18 participants (5 males, mean age ± SD: 34.6 ± 13.6 years) we evaluated the PIPR after exposure to intensified blue light (550 µW/cm²) provided to an undilated dynamic pupil. The test-retest reliability of the primary PIPR outcome parameter was very high, both between day-to-day assessments (Intraclass Correlation Coefficient (ICC) = 0.85), as well as between winter and summer assessments (ICC = 0.83). Compared to the PIPR obtained with the use of mydriatics and 160 µW/cm² blue light exposure, the method with intensified light without mydriatics showed almost zero bias according to Bland-Altman plots and had moderate to strong reliability (ICC = 0.67). In conclusion, for PIPR assessments, increasing the light intensity is a feasible and reliable alternative to pupil dilation to relieve the participant's burden and to allow for performance outside the ophthalmological clinic.

Hyperacuity Exam Screens for Choroidal Neovascularization in Age-Related Macular Degeneration on a Mobile Device

BACKGROUND AND OBJECTIVE

Timely treatment of age-related macular degeneration (AMD) is integral in improving outcomes. To catch choroidal neovascularization as soon as possible, patients should monitor vision at home. The objective of this study is to explore the Hyperacuity App (HAC) as a screen for progression of disease in AMD.

PATIENTS AND METHODS

A cross-sectional, single-center study was performed with 33 subjects. Consent was obtained and patient information was protected in accordance with the protocol approved by the Yale Human Research Protection Program. A masked retinal subspecialist then graded the spectral-domain optical coherence tomography (SD-OCT) taken the same day to determine which patients required treatment. Further data about the patient were obtained through chart review.

RESULTS

The HAC was shown to have 92.3% sensitivity and 61.5% specificity in distinguishing between patients who required treatment and those who did not require treatment.

CONCLUSION

The HAC is a potential screen for choroidal neovascularization in AMD. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:708-715.].

Clear-cornea cataract surgery: pupil size and shape changes, along with anterior chamber volume and depth changes. A Scheimpflug imaging study

PURPOSE

To investigate, by high-precision digital analysis of data provided by Scheimpflug imaging, changes in pupil size and shape and anterior chamber (AC) parameters following cataract surgery.

PATIENTS AND METHODS

The study group (86 eyes, patient age 70.58±10.33 years) was subjected to cataract removal surgery with in-the-bag intraocular lens implantation (pseudophakic). A control group of 75 healthy eyes (patient age 51.14±16.27 years) was employed for comparison. Scheimpflug imaging (preoperatively and 3 months postoperatively) was employed to investigate central corneal thickness, AC depth, and AC volume. In addition, by digitally analyzing the black-and-white dotted line pupil edge marking in the Scheimpflug "large maps," the horizontal and vertical pupil diameters were individually measured and the pupil eccentricity was calculated. The correlations between AC depth and pupil shape parameters versus patient age, as well as the postoperative AC and pupil size and shape changes, were investigated.

RESULTS

Compared to preoperative measurements, AC depth and AC volume of the pseudophakic eyes increased by 0.99±0.46 mm (39%; P<0.001) and 43.57±24.59 mm(3) (36%; P<0.001), respectively. Pupil size analysis showed that the horizontal pupil diameter was reduced by -0.27±0.22 mm (-9.7%; P=0.001) and the vertical pupil diameter was reduced by -0.32±0.24 mm (-11%; P<0.001). Pupil eccentricity was reduced by -39.56%; P<0.001.

CONCLUSION

Cataract extraction surgery appears to affect pupil size and shape, possibly in correlation to AC depth increase. This novel investigation based on digital analysis of Scheimpflug imaging data suggests that the cataract postoperative photopic pupil is reduced and more circular. These changes appear to be more significant with increasing patient age.

Targeted mydriasis strategies for diabetic retinopathy screening clinics

PURPOSE

To examine factors necessitating pupil dilation to achieve gradable diabetic screening photographs using a digital non-mydriatic camera and to establish techniques to predict the need for dilation and to validate them.

METHODS

Prospective clinic-based cross-sectional study with follow-up validation study. The participants' involved consecutive patients attending the diabetic retinopathy screening clinic at a University Hospital. Best corrected visual acuity, age, sex, pupil size, mean spherical equivalent, cataract grade and the requirement for dilation to achieve gradable photographs in 90 patients were recorded. Data analysis using principal component analysis and multivariate analysis of variance derived a set of equations to predict the requirement for dilation. The predictive powers of these equations were validated in an independent group of 51 patients.

RESULTS

Smaller pupil size, denser nuclear colour, older age, poorer best-corrected visual acuity, cortical lens opacity and posterior subcapsular lens opacity were associated with the need for dilation (P<0.001 in all). Single variables used in isolation had a poorer predictive value than combining variables. Dilating patients with either a pupil size>3.75 mm or age>59 years correctly allocates 83 and 78% of patients, respectively to dilation or not. Combining pupil size with age produces a decision table that improves the predictive value to 84%. In the validation study this table had a predictive value of 80%.

CONCLUSION

We have produced and validated criteria based on a range of clinical variables for application in a clinical setting that allows for the development of targeted mydriasis.

Effects of dilation on electronic-ETDRS visual acuity in diabetic patients

PURPOSE

To evaluate the effect of pupillary dilation on electronic-ETDRS visual acuity (EVA) in diabetic subjects and to assess postdilation EVA as a surrogate for predilation VA.

METHODS

DRCR.net-protocol refraction and EVA were measured before and after dilation in diabetic subjects by independent, masked examiners.

RESULTS

In 129 eyes of 66 subjects, the median (25th, 75th percentiles) predilation EVA score was 69 (54, 86) (Snellen-equivalent 20/40(-1) [20/80(-1), 20/20(+1)]). Predilation VA was >or=20/20, <20/20 to 20/40, <20/40 to 20/80, and <20/80 in 29%, 19%, 26%, and 26% of eyes, respectively. Median EVA change postdilation was -3 letters (-7, 0). The absolute change in EVA score was >or=15 letters (>or=3 ETDRS lines) in 9% of eyes and >or=10 letters (>or=2 ETDRS lines) in 19% of eyes. Extent of change (range +12 to -25 letters) was associated with baseline VA. No relationship was identified between EVA change and gender, race, lens status, refractive error, DR severity, or primary cause of vision loss.

CONCLUSIONS

In an optimized clinical trial setting, there is a decline in best corrected EVA after dilation in diabetic subjects. The large range and magnitude of VA change preclude using postdilation EVA as a surrogate for undilated VA.

Patients' attitudes towards mydriasis for diabetic eye disease screening

AIMS

The purpose of the questionnaire was to explore attitudes of patients towards mydriasis for diabetic retinopathy screening.

METHODS

Two groups of patients were invited to take part: group 1 comprised patients attending the diabetic clinic and had previous experience of mydriasis, group 2 patients attending the mobile screening unit for non-mydriatic digital retinal photograph and who were not previously used to receiving mydriatic eye drops. Basic demographic data was recorded and the volunteers invited to complete a questionnaire.

RESULTS

292 patients were recruited into group 1 (median age 63 years range 20-94) and 103 into group 2 (median age 68 years range 29-96). 42% of patients in group 2 indicated that they were unhappy with the use of dilating eye drops and 26% of this group reported that they may be discouraged from attending screening for diabetic retinopathy if drops were introduced. These figures were statistically lower in group 1 at 8% and 1-8% respectively (p < 0.001). Blurring of vision was identified as the most troublesome feature of the use of mydriasis for patients. A large proportion of patients drove themselves to their last screening appointment; 58% in group 2 and 39% in group 1. A third of all patients (33%) indicated that they worked outside the home.

CONCLUSIONS

Many patients attending diabetic eye screening return to driving and work immediately after the appointment. Introduction of the use of routine drops may discourage attendance. Education and experience may have an important role in improving acceptability of mydriatic eye drops. Retinal screeners need to have clear guidelines with which to advise patients.

Can we predict which patients are at risk of having an ungradeable digital image for screening for diabetic retinopathy?

PURPOSE

We aimed to determine the reasons for, and variables which predicted, ungradeable retinal photographs during screening patients for diabetic retinopathy.

MATERIALS AND METHODS

Age, duration of diabetes, visual acuity, and HbA1c were recorded. Following dark adaptation, a single 45 degrees nonmydriatic photograph was taken of each fundus. The pupils were then dilated and the photograph repeated. Using slit lamp biomicroscopy, lenticular changes (LOCS III), and fundus appearance were recorded.

RESULTS

In ungradeable photographs the fovea could not be visualised in 98% of cases of images from nonmydriatic photography, and in 88% if mydriasis was used. Poor definition in the nonmydriatic image was associated with a subsequent ungradeable mydriatic photograph (P=0.001), however, the positive predictive value was poor (34%). Age, posterior subcapsular cataract, and near vision predicted ungradeable status of nonmydriatic photographs (P<0.001, P=0.004, P=0.006, respectively; regression analysis). Nuclear colour and poor definition of the nonmydriatic photograph predicted ungradeable status of mydriatic photographs (P=0.006 & P=0.001, respectively).

CONCLUSION

Inability to visualise the fovea is the commonest cause of an ungradeable image from digital retinal photography. Age and posterior subcapsular cataract were best predictors of ungradeable status of nonmydriatic fundus photographs. Nuclear colour was the strongest predictor for ungradeable mydriatic photography.

Change in dynamic visual acuity (DVA) by pupil dilation

OBJECTIVE

This study was conducted to assess dynamic visual acuity (DVA) under pupil dilation.

BACKGROUND

Pupil dilation may negatively affect driving performance.

METHODS

Thirty healthy young adults (mean age 29.4 years) with pupil dilation participated in this study as the Mydrin P group. In addition to them, 15 healthy young adults (mean age 28.5 years) without pupil dilation were enrolled as the control group. DVA was measured binocularly with free-head viewing at 0, 30, 60, 120, and 360 min after mydriatic drop instillation in both eyes. Pupil size was measured at each time.

RESULTS

In the Mydrin P group, DVA significantly improved at 30, 60, and 120 min (ANOVA; p < .01) but returned to the predilation level at 360 min (ANOVA; p = .61). Pupil size changed from 4.1 to 7.8 mm (ANOVA; p < .01) at 30 min after the instillation, and this level was maintained up to 120 min but returned to normal within 360 min. In the control group, DVA did not significantly change at all measured times (ANOVA; p > .9). DVA was significantly (p < .05) correlated with the pupil size at all measured times.

CONCLUSION

The improvement in DVA was related to the enlargement of the pupil. This study suggests that the pupil size is one factor that may affect DVA.

APPLICATION

Potential applications of this study include useful information to assess the effect of pupil dilation on driving performance.

Changes in chromatic and achromatic contrast sensitivities following tropicamide administration

PURPOSE

To investigate the effects of tropicamide on chromatic and achromatic contrast sensitivities over the physiological range of spatial frequencies.

METHODS

A total of 26 healthy volunteers, with a mean age of 32 years, were examined with and without one drop of 1% tropicamide being administered 30 min previously. On each occasion, acuity and pupil diameter were recorded, and chromatic and achromatic contrast sensitivities were examined using the Sussex Grating Machine.

RESULTS

Following tropicamide administration mean pupil diameter increased from 4.1 mm to 7.2 mm (P<0.001), and mean BCVA was reduced by 0.07 LogMar units (P<0.001). Achromatic contrast sensitivity was significantly reduced following tropicamide administration at 2.20 cycles per degree (cpd) (P=0.01), 3.40 cpd (P=0.01), 10 cpd (P=0.04), 17 cpd (P=0.04), and 25 cpd (P<0.01). There was no difference in contrast sensitivity at lower spatial frequencies (0.33 and 0.66 cpd). Chromatic contrast sensitivity was not significantly altered when tested along the red-green and tritan confusion axes.

CONCLUSIONS

Achromatic contrast sensitivity is significantly reduced following tropicamide administration at intermediate and high spatial frequencies. No significant changes were seen at low spatial frequencies and in chromatic contrast sensitivities.

Pupil dilatation does affect some aspects of daytime driving performance

AIMS

To examine the effects of pupil dilatation on driving performance and determine whether this was related to changes in standard measures of visual function.

METHODS

The driving and vision performance of 16 young, visually normal participants was measured with both normal and dilated pupils. Pupils were dilated with 1% tropicamide. Driving performance was measured under daytime conditions on a closed road circuit that was free of other vehicles and has been used in previous studies of driving performance. Measures included road sign detection and recognition, hazard detection and avoidance, gap perception and negotiation, driving reaction times and time to complete the circuit. Visual performance measures included high contrast visual acuity, Pelli-Robson letter contrast sensitivity, and glare sensitivity.

RESULTS

Pupil dilatation significantly (p<0.05) decreased the ability of participants to recognise low contrast hazards and avoid them, decreased their visual acuity and contrast sensitivity and increased glare sensitivity. The decreases in vision performance were not, however, significantly related to the decrement in driving performance.

CONCLUSION

Pupil dilatation can impair selected aspects of driving and vision performance and patients should be cautioned about these possible effects.

Screening for diabetic retinopathy: a cause for concern in people who drive

AIMS

To report a case of a road traffic accident in a lady driving home from a diabetes clinic after pupillary dilatation. We also present the findings of a questionnaire survey of health professionals to elicit their practice in dealing with such patients.

METHODS

We present the case report of a lady having a road traffic accident on her way back from a retinal screening appointment after having had pupillary dilatation. A subsequent postal questionnaire survey was undertaken to find out current practice in screening patients who drive on the day of their retinal screening.

RESULTS

A lady was involved in a road traffic accident whilst returning home after retinal screening. Her motor insurance company refused to cover subsequent claims for damage because her pupils had been dilated. She was also prosecuted by the police for driving without valid motor insurance. We conducted a postal survey of 500 health care workers including ophthalmologists, optometrists, diabetologists and general practitioners regarding the use of dilating drops in people with diabetes who intend to drive. Analysis of 320 valid responses confirmed that there is no consistent practice with regard to either the use of dilating drops in drivers or in ensuring that arrangements are made for subsequent adequate visual inspection in those whom dilatory drops are not instilled.

CONCLUSIONS

Guidelines, for use by health care professionals and people with diabetes, are clearly required regarding the use of pupillary dilating drops in drivers.

Driving ability after pupillary dilatation

BACKGROUND

The Royal College of Ophthalmologists' guidelines and Driver and Vehicle Licensing Agency (DVLA) recommend that a patient should not drive with dilated pupils based on the rationale that vision may be compromised in acuity and ability to tolerate glare. Arguments exist against these recommendations suggesting that pupillary dilatation does not have any real bearings on driving ability. Aim To determine the effects of pupillary dilatation on the ability to drive.

METHODS

The study was randomised and prospective. A total of 28 patients had their visual parameters (distance vision, near vision, licence plate reading at 20 m or shorter, and glare) measured and analysed pre- and post-tropicamide 1% dilatation. Paired two-tailed Student's t-test and chi(2)-test were used in the analysis.

RESULTS

At 20 min, following instillation of one drop of tropicamide 1% there is a significant reduction in visual acuity (VA), for distance Snellen and near. There is a significant reduction in the number of people who could read the licence plate at 20 m. Subjective glare assessment changed from 'none' (average score) in the undilated state to 'mild' in the dilated states. The overall patient feedback indicated that a significant 14% believed they would find it difficult to drive postdilatation.

CONCLUSION

This study demonstrates the rationale behind disallowing driving following pupillary dilatation. The risks to safe driving are proved significant as a result of significant reduction in visual quality and quantity after dilatation.