Short-term effects of cyclopentolate and tropicamide eye drops on macular choroidal thickness in myopic children

BACKGROUND

To investigate the short-term effects of cyclopentolate and tropicamide eyedrops on choroidal thickness (ChT) in myopic children using placebo or low-dose atropine eyedrops.

METHODS

The analysis included 242 myopic individuals (7-19 years) enrolled in two randomised placebo-controlled clinical trials of low-dose atropine eyedrops. Cycloplegia was induced using either one drop of 1% cyclopentolate (n = 161), two drops of 1% cyclopentolate (n = 32) or two drops of 1% tropicamide (n = 49). ChT measurements were taken using swept-source optical coherence tomography before and 30 min after administering the cycloplegic eye drops. A subset of 51 participants underwent test-retest measurements prior to cycloplegia.

RESULTS

Mean changes in subfoveal ChT after two drops of tropicamide and one and two drops of cyclopentolate were -2.5 μm (p = 0.10), -4.3 μm (p < 0.001) and -9.6 μm (p < 0.001), respectively. Subfoveal ChT changes after one and two drops of cyclopentolate were significantly greater than the test-retest changes (test-retest mean change: -3.1 μm; p < 0.05), while the tropicamide group was not significantly different (p = 0.64). Choroidal thinning post-cyclopentolate was not significantly different between atropine and placebo treatment groups (p > 0.05 for all macular locations). The coefficient of repeatability (CoR) in the tropicamide group (range: 8.2-14.4 μm) was similar to test-retest (range: 7.5-12.2 μm), whereas greater CoR values were observed in the cyclopentolate groups (one drop: range: 10.8-15.3 μm; two drops: range: 12.2-24.6 μm).

CONCLUSIONS

Cyclopentolate eye drops caused dose-dependent choroidal thinning and increased variation in pre- to post-cycloplegia measurements compared with test-retest variability, whereas tropicamide did not. These findings have practical implications for ChT measurements when cyclopentolate is used, particularly for successive measurements.

Method comparison and overview of refractive measurements in children: implications for myopia management

OBJECTIVE

This study investigated the agreement between objective wavefront-based refraction and subjective refraction in myopic children. It also assessed the impact of cyclopentolate and refraction levels on the agreement.

METHODS

A total of 84 eyes of myopic children aged 6-13 years were included in the analysis. Non-cycloplegic and cycloplegic objective wavefront-based refraction were determined and cycloplegic subjective refraction was performed for each participant. The data were converted into spherical equivalent, J0 and J45, and Bland-Altman plots were used to analyse the agreement between methods.

RESULTS

Linear functions were used to determine the dependency between the central myopic refractive error and the difference between the method of refraction (=bias). The influence of central myopia was not clinically relevant when analysing the agreement between wavefront results with and without cyclopentolate (comparison 1). The bias for wavefront-based minus subjective spherical equivalent refraction (comparison 2) was ≤-0.50 D (95% limits of agreement -0.010 D to -1.00 D) for myopia of -4.55 D and higher when cycloplegia was used (p<0.05). When no cyclopentolate was used for the wavefront-based refraction (comparison 3), the bias of -0.50 D (95% limits of agreement -0.020 D to -0.97 D) was already reached at a myopic error of -2.97 D. Both astigmatic components showed no clinically relevant bias.

CONCLUSION

The spherical equivalent, measured without cycloplegic agents, led to more myopic measurements when wavefront-based refraction was used. The observed bias increased with the amount of myopic refractive error for comparisons 2 and 3, which needs to be considered when interpreting wavefront-refraction data.

TRIAL REGISTRATION NUMBER

NCT05288335.

Comparison of cycloplegia with atropine 1% versus cyclopentolate 1

PURPOSE

Cycloplegic refraction is mandatory for children to know the eye's refractive status. In this study, we compared cycloplegia induced by cyclopentolate 1% to that induced by atropine 1% by means of retinoscopy.

METHODS

In this parallel-designed interventional study, we included 67 children aged between 4 and 17 years. After the initial retinoscopy under cyclopentolate 1% (used twice in each eye), we repeated it a week later under atropine ointment 1% (used twice a day for 3 days); both were done by the same trained optometrist masked to the drug. Each eye's refraction was converted to spherical equivalents (SEs), and the values averaged between the two eyes of each child under each drug. We compared SE with paired t-test (JASP 16.4). In addition, we performed correlational analysis, and looked for agreement using the Bland-Altman plot. Significance was set at P < 0.05. Wherever possible, 95% confidence intervals (CIs) are quoted.

RESULTS

The mean SE with atropine was +1.93 ± 2.0 D, compared to +1.75 ± 1.95 D under cyclopentolate. On average, atropine induced greater cycloplegia by a mere 0.18 D (95% CI: 0.07 to 0.29 D, P value 0.002). The two cycloplegic refractions correlated significantly (Pearson's r: 0.975, P < 0.001). The Bland-Altman plot revealed the limits of agreement as 1.06 and -0.71 D.

CONCLUSION

Our study suggests that cyclopentolate works for the most part as well as atropine to attain cycloplegia. Atropine may be considered for children less than 15 years of age with greater than 5.0 D of hyperopia. Cycloplentolate, with its advantages of quick action and short duration, should form the first go-to topical cycloplegic in busy outpatient clinics.

EEG changes as an indication of central nervous system involvement following cyclopentolate 1% eye drops; a randomized placebo-controlled pilot study in a pediatric population

To compare EEG-patterns after instillation of cyclopentolate versus placebo eye drops. Prospective, randomized, placebo-controlled, and observational pilot study is presented. Ophthalmology outpatient clinic Dutch metropolitan hospital. Healthy 6- to 15-year-old volunteers with normal or low BMI requiring a cycloplegic refraction/retinoscopy. Randomized; 1 visit 2 drops cyclopentolate-1% and 1 visit 2 drops placebo (saline-0.9%). Single-blind: conducting researcher. Double blind: subjects, parents, clinical-neurophysiology staff, neurologist, and statistician. A 10-min baseline EEG-recording, drop-application, and follow-up to at least 45 min. Primary outcome: Detection of CNS changes, i.e. EEG-pattern changes, following two drops of cyclopentolate-1%. Secondary outcome: Determination of the extent of these pattern changes. Thirty-six cyclopentolate-1% saline-0.9% EEG registrations were made in 33 subjects;  18 males and 15 females. Three subjects were tested twice (interval 7 months). Nine out of fourteen (64%) of the 11- to 15-year-old children reported impaired memory, attention, alertness, as well as mind wandering following cyclopentolate. Drowsiness and sleep were seen in EEG-recordings of 11 subjects (33%) following cyclopentolate. We observed no drowsiness nor sleep during placebo recordings. The mean time to drowsiness was 23 min. Nine subjects arrived in stage-3 sleep but none arrived in REM-sleep. In subjects without sleep (N=24), significant changes compared to placebo-EEG were present for many leads and parameters. The main findings during awake eye-open recording were as follows: 1) a significant increase of temporal Beta-1,2 and 3-power, and 2) a significant decrease in: a) the parietal and occipital Alpha-2-power, b) the frontal Delta-1-power, c) the frontal total power, and d) the occipital and parietal activation synchrony index. The former finding reflects cyclopentolate uptake in the CNS, and the latter findings provide evidence for CNS suppression. Cyclopentolate-1% eye drops can affect the CNS and may cause altered consciousness, drowsiness, and sleep with concomitant EEG results in both young children and children in puberty. There is evidence that cyclopentolate has the potency to act as a short acting CNS depressant. Nevertheless, however, cyclopentolate-1% can safely be used in children and young adolescents.

Evaluation of a Pilot Protocol for Detecting Infant Hyperopia

SIGNIFICANCE

Highly hyperopic children are at greater risk for developing conditions such as strabismus, amblyopia, and early literacy and reading problems. High hyperopia is a common finding in infants in a pediatric medical practice, and early detection can be done effectively in that setting with tropicamide autorefraction.

PURPOSE

This study aimed to evaluate the effectiveness of a pilot screening program to detect high hyperopia in 2-month-old infants in a pediatric medical practice in Columbus, Ohio.

METHODS

Cycloplegic refractive error (1% tropicamide) was measured by retinoscopy and autorefraction with the Welch Allyn SureSight (Welch Allyn/Hillrom, Skaneateles Falls, NY) in 473 infants (55.4% female) who were undergoing their 2-month well-baby visit at their pediatrician's medical practice. Cycloplegic retinoscopy (1% cyclopentolate) was repeated at a subsequent visit in 35 infants with ≥+5.00 D hyperopia in the most hyperopic meridian during the screening.

RESULTS

Twenty-eight infants (5.9%) had high hyperopia (spherical equivalent, ≥+5.00 D), and 61 (12.9%) had high hyperopia (≥+5.00 D in at least one meridian of at least one eye) by retinoscopy with 1% tropicamide. The mean ± standard deviation spherical equivalent tropicamide cycloplegic refractive error measured with retinoscopy was +2.54 ± 1.54 D (range, -3.25 to +7.00 D) and with SureSight was +2.29 ± 1.64 D (range, -2.90 to +7.53 D). Retinoscopy done using 1% cyclopentolate was 0.44 ± 0.54 D more hyperopic in spherical equivalent than with 1% tropicamide ( P < .001).

CONCLUSIONS

High hyperopia was a common finding in 2-month-old infants in a pediatric medical setting that could be detected effectively by cycloplegic autorefraction using tropicamide. Greater cooperation between pediatric primary vision and medical care could lead to effective vision screenings designed to detect high hyperopia in infants.

Compensation for Vitreous Chamber Elongation in Infancy and Childhood

SIGNIFICANCE

The ratios of diopters of change in refractive error produced per millimeter of eye elongation (D/mm) are rarely those predicted from geometric optics because of changes in other ocular components. Quantifying this optical compensation in millimeters instead of ratios reveals some important principles about eye growth and refractive error.

PURPOSE

The study purpose was to sort total vitreous chamber elongation into millimeters that either contributed (uncompensated) or did not contribute to change in refractive error (compensated).

METHODS

Participants were infants in the Berkeley Infant Biometry Study (n = 271, ages 3 months to 6 years) or schoolchildren in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (n = 456 emmetropes and 522 myopes, ages 6 to 14 years). Refractive error was measured using cycloplegic retinoscopy in infants (cyclopentolate 1%) and cycloplegic autorefraction in schoolchildren (tropicamide 1% or combined with cyclopentolate 1%). Axial dimensions were assessed using A-scan ultrasonography. Uncompensated millimeters were estimated from ratios of change in refractive error per millimeter of elongation using Gullstrand eye models. Compensated millimeters were the difference between measured elongation and uncompensated millimeters.

RESULTS

Compensated millimeters exceeded uncompensated millimeters in emmetropic children across ages, but uncompensated millimeters exceeded compensated millimeters in myopic children. Compensated millimeters were highest in infancy and decreased with age, reaching less than 0.10 mm per year by age 10 years in both myopic and emmetropic children. There were no statistically significant differences in compensated millimeters between myopic and emmetropic children between ages 8 and 14 years ( P values from .17 to .73).

CONCLUSIONS

The ability of the ocular components, primarily crystalline lens, to compensate for vitreous elongation is independent of the higher demands of myopic eye growth. The limited compensation after age 10 years suggests the target for elongation in myopia control needed to arrest myopia progression may be that seen in emmetropes or less.

Cycloplegic Autorefraction as a Substitute for Cycloplegic Retinoscopy in the Pediatric Population

PURPOSE

To evaluate whether cycloplegic autorefraction can provide similar results as cycloplegic retinoscopy, allowing more comprehensive ophthalmologists to be comfortable in managing pediatric refractive error and refractive amblyopia.

METHODS

This retrospective chart review was performed to determine the mean difference in sphere, cylinder, and axis between cycloplegic autorefraction and retinoscopy, both of which were obtained on the same eye at least 30 minutes after cycloplegia and dilation with a mixed solution of tropicamide, cyclopentolate, and phenylephrine.

RESULTS

A total of 34 eyes (18 right, 16 left) from 18 patients were included in the analysis. Mean sphere difference between cycloplegic autorefraction and retinoscopy was 0.044 ± 0.278 diopters (D) (95% CI: -1.275 to 1.363 D), mean cylinder difference was -0.081 ± 0.236 D (95% CI: -0.706 to 0.544 D), and mean axis difference was 7.059 ± 19.676 degrees (95% CI: -32.527 to 38.878 degrees). Mean differences in sphere, cylinder, and axis were not statistically significant (P = .362, .0541, and .377, respectively).

CONCLUSIONS

In this small sample population, cycloplegic autorefraction was comparable to cycloplegic retinoscopy. Recognition of amblyopia should still prompt evaluation by a pediatric ophthalmologist. Further research is necessary to confirm whether uncomplicated refractive error in children may be sufficiently detected and managed by a comprehensive ophthalmologist. [J Pediatr Ophthalmol Strabismus. 2022:59(6):422-427.].

Comparison of the Near Eye Tool for Refractive Assessment (NETRA) and non-cycloplegic subjective refraction

Objective

The NETRA (Near Eye Tool for Refractive Assessment) is a smartphone-based refractive tool that allows for self-evaluation of refractive error. This study investigates the validity of the NETRA with and without cycloplegia to non-cycloplegic subjective refractions (SR).

Methods and analysis

Participants underwent NETRA measurements without cycloplegia, and again after the administration of cycloplegia (cyclopentolate hydrochloride 1%). Non-cycloplegic SR were also performed. Variation of refractive measurements in symmetric dioptric power space were investigated using stereo-pair comets, hypothesis tests for variances and means. Bland-Altman plots were applied to better understand validity of the NETRA against non-cycloplegic SR. Coefficients of repeatability and intraclass correlation coefficients were also determined.

Results

The sample included 22 women (64.7%) and 12 men (35.3%); most were indigenous Africans (52.9%) with mean age and SD of 20.24±1.95 years. Variation of refractive measurements were mainly stigmatic (spherical), and variation of NETRA measurements decreased after cycloplegia. The pre-cycloplegia NETRA measurements (and their means) for the right and left eyes were more negative (myopic) in power than the post-cycloplegia NETRA measurements and means. On average, eyes were approximately 1.25 D more myopic with the NETRA without cycloplegia. With cycloplegia, NETRA results were in closer agreement with non-cycloplegic SR for the same eyes.

Conclusion

NETRA validity to SR, even in the absence of cycloplegia, suggests the instrument may be useful in geographical regions where self-refractions might be potentially helpful in addressing limitations in eye and vision care.

Correlation and agreement between the Mohindra and cycloplegic retinoscopy techniques in children

PURPOSE

As an objective technique to assess refractive status, retinoscopy is particularly useful in children. The Mohindra technique (RM) is an alternative for those patients not good candidates for cycloplegic retinoscopy (RC). The aim of the present research was to compare both techniques and to determine the correlation and agreement of their measurements.

MATERIAL AND METHODS

A total of 47 boys and girls of ages ranging from 3 to 11 years old were included in the study. Cycloplegic (cyclopentolate 1%) and Mohindra retinoscopy were conducted in both eyes, and refraction was also assessed with an autorefractometre (AR). The results from the three techniques were compared and a correction factor between RM and RC was calculated.

RESULTS

Statistically significant differences were found between RM and RC (median of -0.42 D; p < 0.001) and between RM and AR (median of -0.42 D; p = 0.008), but not between RC and AR (median of 0.00 D; p = 0.758). A strong correlation was found between RM and RC (rho = 0.846; p < 0.001), although the Bland-Altman test revealed a larger difference between these techniques in patients with larger hyperopic refractive errors, with a correction factor of RC = 1.15 RM + 0.42.

CONCLUSIONS

The Mohindra technique may be considered a valid alternative to cycloplegic retinoscopy in patients of young age, with a good correlation between both techniques, albeit less agreement in patients with high hyperopic refractions.

Quantifying the cost of single-use minims and multidose bottles for eye drops in routine ophthalmic practice: a multicentre study

OBJECTIVE

To compare costs between two different eye drop delivery modalities: multidose bottles and single-use minims.

DESIGN

Retrospective cohort study.

METHODS

Monthly dilating eye drop costs and quantities (tropicamide 1%, phenylephrine 2.5%, cyclopentolate 1%) were studied over a 2-year period between April 2013 and March 2015 at 2 tertiary ophthalmic centres (Royal Alexandra Hospital [RAH, Edmonton] and Rockyview General Hospital [RGH, Calgary]). In April 2014, RAH switched its dilating eye drop practice from predominantly multidose bottles to single-use minims, whereas RGH continued using predominantly multidose bottles. Eye drop volume and total and per-patient eye drop costs were quantified at RAH before switching (pre-intervention) and after (post-intervention) using an interrupted time-series analysis with RGH as a control. A counterfactual analysis was also performed. Significance was obtained using independent t-testing.

RESULTS

After switching to single-use minims, RAH experienced changes in the following: an increase in single-use minims as a proportion of total eye drop utilization (from 5.6% to 89.1%; p = 0.001), an increase in total eye drop cost by $2117 per month (95% confidence interval [CI], $1354-$2880; p < 0.001), an increase in per-patient costs by $984 per 1000 patients per month (95% CI, $674-$1293). Contrastingly, RGH did not experience similar changes. Ultimately, the cost of switching to single-use minims was $22 481 (95% CI, $7830-$31 336) over a 12-month period.

CONCLUSIONS

If safe eye drop practices are enforced via proper protocols, the use of multidose bottles may be a more cost-effective option than single-use minims for routine clinical practice.

Introducing a new method of retinoscopy for refraction of infants and young children: The "Mirza" tele lens retinoscopy

PURPOSE

This study aimed to evaluate the refractive error of the uncooperative infants and children with the new method of retinoscopy called the tele-lens ("Mirza") retinoscopy.

METHODS

In the "Mirza" tele-lens retinoscopy, the examiner placed the trial lenses in 1/3 distance between the tested eye person and peephole of the retinoscope (22.2 cm far from the spectacle plane). First, the optical calculations were done to find the correction factors for this new method of retinoscopy. Second, the dry standard and "Mirza" tele-lens retinoscopy were performed in 78 eyes from 39 children aged 7-12 years with good cooperation and next, the procedure was repeated using cyclopentolate drops and then the results of the two methods were compared, and at the end, the dry "Mirza" tele-lens retinoscopy was done in the 60 eyes of 31 uncooperative infants with a mean age of 21.85 ± 8.79 months for evaluating the feasibility of the "Mirza" tele-lens retinoscopy procedure. The intraclass correlation coefficient (ICC) and Bland-Altman plot for assessment of agreement between the findings of two retinoscopic methods in dry and cyclo conditions were used.

RESULTS

The comparison between the dry standard and "Mirza" tele-lens retinoscopic results with means of 1.39 ± 1.43 and1.36 ± 1.39, respectively were not statistically significant (p > 0.05). Besides, comparing the mean cycloplegic results of two methods (standard vs. "Mirza" tele-lens), the difference was not statistically significant (2.37 ± 1.44 vs. 2.41 ± 1.37) (p > 0.05). Moreover, Two-way repeated measures ANOVA revealed no significant retinoscopy method × use of drops interaction (P = 0.103) in comparing two methods of the standard and "Mirza" tele-lens retinoscopy. ICC results indicated high agreement between two methods in both dry (ICC = 0.993) and cyclo (ICC = 0.989) conditions.

CONCLUSIONS

The "Mirza" tele-lens retinoscopy method can be performed with satisfactory results in infants and children who do not cooperate for the standard procedure of measuring the refractive errors.

Is the Sphere Value Measured by an Autorefractor Reliable in Children under Cycloplegia? Comparison with Streak Retinoscopy

PURPOSE

To compare and repeatedly measure cycloplegic refraction in a cross-section of children using retinoscopy and automated refraction.

METHODS

A total of 560 children (corresponding to 1120 eyes) ranging in age from 3 to 10 years participated in the study. Each child underwent a comprehensive eye examination, which included table mounted autorefractor evaluation (Kowa KW-2000) and streak retinoscopy, both after cycloplegia with 1% cyclopentolate hydrochloride. Data were analyzed using Fourier decomposition of the power profile.

RESULTS

More positive values of M component and sphere value were given by cycloplegic autorefraction (AKW) compared with cycloplegic streak retinoscopy (RR). More negative values for the J45 vector and more positive for J0 were given AKW although this difference was not statistically significant.

CONCLUSIONS

Our study shows that the table mounted autorefkeratometer Kowa KW- 2000 can be applied to young children with cycloplegia as instrument for cycloplegic refraction, and a discount of +0.67 should be applied on the sphere value. Similar care should be taken on the evaluation of the sphere and spherical equivalent values should be applied in other devices.

Wave-front analysis as screening technique for amblyogenic ametropia with and without cycloplegia

INTRODUCTION

For many years, attempts have been made to find an easy, efficient and inexpensive method to screen children for amblyogenic ametropia. Wave-front analysis is a new way to determine the refractive state of the eye from a distance. This technique could be a useful tool for infant screening.

PURPOSE

The purpose of the study was the evaluation of the efficacy of a commercially available wave-front analyzing autorefractometer (SureSight, software version 2.0, Welch Allyn, Skaneateles Falls, NY 13153, U.S.A.) in detecting amblyogenic ametropia in patients with and without cycloplegia.

METHODS

256 eyes (-28.25 D to +7.88 D spherical equivalent) of 128 patients (1-81 years) were examined with the wave-front autorefractometer under cycloplegia. Prior to this investigation, 108 eyes (-21.38 D to 75 D) of 54 of these patients (1-76 years) were refracted without cycloplegia. The readings of the wave-front autorefractometer were compared with the results of retinoscopy under cycloplegia.

RESULTS

Without cycloplegia, the sensitivity in detecting any amblyogenic ametropia such as anisometropia, astigmatism, myopia or hyperopia was 94%, while the specificity was 63%. Following cycloplegia, the sensitivity decreased to 87% and the specificity increased to 80%.

CONCLUSION

Wave-front analyzing refractometry is highly applicable for infant screening. At the present state of development, the efficacy in detecting amblyogenic ametropia is similar to that of other screening techniques and instruments that operate from distance. Cycloplegia enhances the sensitivity in detecting hyperopia and decreases the sensitivity in detecting astigmatism.

Necessity of cycloplegia for assessing refractive error in 12-year-old children: a population-based study

PURPOSE

To compare pre- and postcycloplegic autorefraction in two separate age samples of Australian school children.

DESIGN

Population-based cross-sectional study of random cluster samples.

METHODS

Autorefraction was performed before and after cycloplegia, using 1% cyclopentolate, in the right eyes of 2,233 12-year-old and 210 6-year-old children.

RESULTS

The mean spherical equivalent (SEQ) difference between these measures was 0.84 diopters (D) (95% confidence interval (CI) 0.81 to 0.87 D), more hyperopic in post- than precycloplegic autorefractive assessments in the 12-year-old children and 1.18 D (95% CI 1.05 to 1.30 D) more hyperopic in the 6-year-old children. Precycloplegic autorefraction substantially overestimated the proportion of children with myopia, misclassifying 17.8% aged 12 years and 9.5% aged 6 years. Conversely, precycloplegic autorefraction did not detect moderate to high hyperopia in 2.28% of 12-year-olds and 17.14% of 6-year-olds.

CONCLUSIONS

Our findings reinforce the importance of using cycloplegic autorefraction in children up to age 12 years.

Reproducibility and accuracy of measurements with a hand held autorefractor in children

AIM

To determine reproducibility and accuracy of the Nikon Retinomax autorefractor when used with children who were made cycloplegic.

METHODS

Autorefraction and retinoscopy or subjectively refined retinoscopy (where, under the patient's direction, the refraction was varied until the best visual acuity was achieved) were performed on the right eye of 47 children, age 11-93 months. Autorefraction was performed using the Nikon Retinomax, which provides up to eight measured values of refractive error and one representative measurement of refractive error.

RESULTS

Autorefractor measurements were successfully obtained from 7/9 children age 3 years or younger, and from all older children. Vector methods were used to calculate differences. Retinomax reproducibility averaged 0.43 D. Unbiased Retinomax and retinoscopy measurements differed by an average of 0.82 D. Unbiased Retinomax and subjectively refined retinoscopy differed by an average of 1.03 D.

CONCLUSIONS

Reproducibility of Retinomax measured values in children is comparable with reproducibility of retinoscopy, subjective refraction, and autorefraction measurements in adults. Agreement between Retinomax and retinoscopy and agreement between Retinomax and subjective refinement in children is comparable with agreement between autorefraction and subjective refraction in adults. The study indicates that the Retinomax is a useful instrument for measuring refractive errors in young children.

Sterility of ophthalmic drugs dispensed from spray bottles

BACKGROUND

Spray application of cycloplegics and mydriatics is efficacious and frequently easier to use than a standard dropper bottle in the pediatric population. However, no documentation regarding the sterility of drugs dispensed from spray bottles is available. This study was conducted to determine whether contamination of ophthalmic drugs occurs with spray bottle use.

METHODS

Fifteen milliliters of 1% cyclopentolate hydrochloride or 0.5% tetracaine hydrochloride were transferred to each of 15 disinfected spray bottles, stored at room temperature or refrigerated, and sprayed three times weekly for 12 weeks. Cultures were obtained from the spray bottles and drugs before transfer of the drug and from spray bottle contents at 0, 2, 4, and 6 to 12 weeks of storage.

RESULTS

No cultures showed significant bacterial growth. The bactericidal action of the preservative and sterility of the drugs were maintained.

CONCLUSIONS

Despite the transfer to and use of a spray bottle there appears to be minimal risk of instilling contaminated diagnostic drugs using the spray method when a single drug is stored in a spray bottle.

Effects of target distance and pupil size on letter contrast sensitivity with simultaneous vision bifocal contact lenses

Using simulated presbyopia we measured the effects of target vergence and pupil size on letter contrast sensitivity while subjects wore accurately centered simultaneous vision bifocal contact lenses. These experiments examined the increase in depth of focus provided by two bifocal contact lenses, and the effects of pupil size on near and distance vision. Monocular contrast sensitivity was assessed with three different designs of soft contact lenses. First, as a single vision control, we measured contrast sensitivity with a Bausch & Lomb, Optima 38 lens corrected for distance. We then measured contrast sensitivity with an Allergan Optical, Hydron Echelon, which is a diffractive simultaneous bifocal and a CIBA Vision, Spectrum, which is a concentric design, center-near, two-zone simultaneous vision bifocal. In general both bifocal contact lenses improved contrast sensitivity at near but decreased contrast sensitivity at distance (when compared to the single vision lens). With a fixed 3.5-mm artificial pupil, the Echelon lens had two clear peaks of sensitivity, one at distance (0.00 D) and one at near (-2.00 D), but the Spectrum lens had no clear peaks. Performance of the Spectrum lens depended on its center zone size. Near (-2.00 D) and distance (0.00 D) contrast sensitivity was measured with pupil sizes that ranged from 1 to 6 mm. The results showed that visual performance with a diffractive lens was almost independent of pupil diameter up to 3 to 4 mm but, as predicted, performance with the two-zone lens depended critically on pupil size.

Can retinoscopy be used to screen infants for amblyopia? A longitudinal study of refraction in the first year of life

One hundred normal babies were refracted by two observers in a double-masked study within 24 hours of delivery and 30 minutes after instillation of 1% cyclopentolate. The procedure was repeated at 6 weeks, 3 months, 6 months and 1 year. At birth agreement between the two refractionists to within 1 dioptre spherical equivalent was 82%, rising to 94% at 1 year. Astigmatism of greater than 1 dioptre increased from 10% at birth to 42% at 6 months but decreased to 15% at 1 year. Myopia was uncommon (4%) but 80% of eyes were hypermetropic more than +2 dioptres and 25% more than +4 dioptres at birth, although these percentages decreased to 5% and 3% at 1 year. Anisometropia of more than 1 dioptre between the two eyes was uncommon but in the two cases where it persisted in the presence of high hypermetropia, reversible amblyopia was encountered in both cases.

Effect of reduced accommodative response on isoluminance stereothreshold

A previous study has shown that stereothreshold varies as a function of the luminance difference between a target and its background. On the average, the stereothreshold at the isoluminance point is three times higher than when there is maximum luminance difference between the target and the background. One of the possible reasons for this finding is the effect of less than optimum accommodative response for isoluminant targets. This possibility has been investigated in this study. The results show that the suboptimal accommodative response cannot explain the high stereothreshold at isoluminance.

Precision in automated refraction

Forty-six eyes were examined with automated refraction with the Nidek 1000-AR autorefractometer to determine how large variation there was in readings of each patient, under dry conditions (without cycloplegia) and in atropine and cyclopentolate cycloplegia. Likewise, the differences between methods of cycloplegia were analysed with regard to sphere, cylinder power, and axis. Overall the variation in each set of measurements was greatest for the spherical component, and a larger variation was found in the youngest age group. Variation in cylinder power and axis was small. Cycloplegics had a significant influence on the spherical component of automated refraction, and a mean difference of 0.76D was found between atropine and dry readings, and 0.23D between atropine and cyclopentolate readings. The differences between cycloplegic and dry readings in cylinder power and axis were insignificant. A regression model relating spherical power of dry and cyclopentolate automated refraction was developed, and the predictive power of this equation was tested.

The Canadian Optometry Survey: report on the utilization of diagnostic pharmaceutical agents by Canadian optometrists

This study represents the first national survey of optometrists in Canada. A mailed questionnaire was designed and implemented in order to discover how optometrists have reacted to the introduction of diagnostic pharmaceutical agent (DPA) legislation in Canada and to determine what variables are important predictors of DPA use. The data collected were also used to test the null hypothesis that DPA legislation does not affect the use of mydriatic/cycloplegic agents by optometrists. A stratified random sampling procedure was used to select 230 optometrists (roughly 10% of the practicing profession) for inclusion in the study. Over 90% of the subjects completed and returned the questionnaire. A statistically significant and important association was found between mydriatic/cycloplegic drug use and legislation (p less than 0.05 and odds ratio = 2.18). Legislation, type of practice, age, and optometry school attended were all found to be associated with DPA use.

Holes in clear lenses demonstrate a pinhole effect

This study describes a new variant of the pinhole principle. Holes drilled in clear plastic lenses held in combination with a blurring lens can overcome the blurring effect much as a traditional pinhole. Specifically, this study shows how holes of different diameter placed in lenses of different spherical power can improve visual acuity that has been degraded by a series of blurring spherical lenses. In general, the hole in the clear lens improves visual acuity for progressively stronger blurring lenses.

The effect of cycloplegia on the visual contrast sensitivity function

Contrast sensitivity assessment is one of several emergent techniques being considered for inclusion in a visual standards test battery for the Army, particularly for the evaluation of Army aviators. Since a cycloplegic refraction is required for initial selection of candidates for Class I and Class IA flying duty, it is important to determine what effect, if any, cycloplegia has on the contrast sensitivity function. There were 12 subjects tested, all officers in preparation for flight training who had passed a recent Class I flight physical. Contrast sensitivity functions were obtained under normal ambient conditions and in the presence of a glare source both under manifest and cycloplegic conditions. Cycloplegia produced a small reduction in contrast sensitivity under normal ambient conditions, and a greater reduction under glare conditions. For both conditions, the cycloplegia effect was greater for the higher spatial frequency gratings than for the lower.

Abolition of feeding intolerance following ophthalmologic examination of neonates

Administration of mydriatic medication and ophthalmologic examination have previously been associated with feeding intolerance, characterized by large retained gastric aspirates and abdominal distention. In an attempt to eliminate this problem, we instituted a policy of withholding feedings for four hours following ophthalmologic examination. A prospective series of 50 consecutive patients was then followed to determine the incidence of feeding intolerance 24 hours prior to and 24 hours following the examination. All infants had received cyclopentolate hydrochloride and phenylephrine hydrochloride prior to the examination. A critical review of the nursing notes revealed no increased incidence in feeding intolerance during the 24-hour period following examination. There were no cases of necrotizing enterocolitis during either period. This study provides evidence that the incidence of feeding intolerance following ophthalmologic examinations might be reduced by withholding feeding for four hours after the examinations.

Cycloplegic refraction in esotropic children. Cyclopentolate versus atropine

Retinoscopy was performed on a population of predominantly white esotropic children younger than 5.5 years with cyclopentolate 1% and atropine 1.0%. Atropine 1.0% revealed +0.34 diopters more hyperopia than cyclopentolate 1.0%, when the mean differences between the two drugs were examined. Mean difference analysis would probably indicate that atropine retinoscopy was unnecessary. However, 22% of the children had +1.0 diopters or more of hyperopia uncovered by atropine. This significant subpopulation suggests that in young patients with esotropia, an atropine refraction is essential to uncover the maximum amount of hyperopia. Almost all of this subgroup with +1.00 or greater hyperopia had an initial cyclopentolate retinoscopy of +2.00 diopters or more. Therefore, retinoscopy using atropine cycloplegia becomes even more important in this population. There was a trend for the greater differences to be in children older than age 2 years. However, these values were not statistically significant.

Cycloplegic refractions in infants and young children

We studied groups of normal infants and infants with amblyopia and esoropia to determine the incidence of infantile astigmatism. Under cycloplegia, 19% of normal infants had astigmatism; this was at least twice the incidence in adults, but less than one-hale that found by noncycloplegic refractions of infants. During the first three postnatal years the incidence of astigmatism and distributions of spherical equivalents and anisometropia did not distinguish normal patients from most of those with esotropia and amblyopia.

The effect of cycloplegia on the determination of refractive error by the Ophthalmetron

The Ophthalmetron was used to measure the refractive error of 10 male optometry students. Although there was a high incidence of invalid readings, more repeatable results were obtained with use of a cycloplegic. Measurements made under cycloplegia revealed 0.41 D more hyperopia but no differences in astigmatism as compared to the noncycloplegic refraction. Instrument myopia was shown not to be a factor.

The cyclopentolate provocative test in suspected or untreated open-angle glaucoma. IV. Fluorescein angiography of the vessels of the iris in open-angle glaucoma eyes with a positive cyclopentolate response

Fluorescein angiography of the iris (IFAG) was performed on 15 patients with a positive cyclopentolate response (IOP elevation greater than or equal to 8 mmHg) in 17 eyes to the cyclopentolate provocative test. The chamber angles were open in all the eyes. Seven of the responder eyes had capsular glaucoma undergoing treatment, six had simple glaucoma, two had pigmentary glaucoma and two suspicion of open-angle glaucoma. The object was to study with IFAG whether vascular changes can be established in the iris of the responder eyes such as could have a role in the elevation of IOP. All the eyes with capsular glaucoma displayed vascular changes, vasoproliferation and fluorescein leakage from the iris vessles. No other vascular changes were seen in the irises of the responder eyes. IFAG revealed no differences in the iris vasculature between responder and non-responder eyes. A vascular aetiology for the IOP elevation in responders is improbable.

The cyclopentolate provocative test in suspected or untreated open-angle glaucoma. III. The significane of pigment for the result of the cyclopentolate provocative test in suspected or untreated open-angle glaucoma

Significant elevations of IOP, i. e. responses, occurred in eyes with suspected or untreated open-angle glaucoma during the mydriasis test with 1% cyclopentolate (CPT). The possible role of pigment in the IOP elevations seen in the responders was studied. Pigment was liberated in the aqueous, sometimes very profusely, in 88 (31.9%) of 276 eyes during CPT. The maximal IOP elevations, ad 20 mmHg, were seen in just these eyes. They were eyes with capsular or pigmentary glaucoma or eyes in which exceptionally heavy pigment was demonstrated in the chamber angle for other reasons. There was a statistically significant correlation between pigment liberation and IOP elevation during CPT. Evidently profuse pigment liberation may have caused transient blocking of the trabecular meshwork, obstruction of aqueous outflow and elevation of IOP. Liberation of pigment in the aqueous during CPT was statistically highly significantly more profuse in eyes with pseudoexfoliation than in eyes without pseudoexfoliation. An equally significant correlation with demonstrated between the grade of chamber angle pigmentation and the degree of pigment liberation during CPT. The significance of pigment for IOP elevation was seen also in the statistically highly significantly more profuse pigmentation of the chamber angle in the responder than in the non-responder eyes.