Prior topical anesthesia reduces time to full cycloplegia in Chinese

Comparison of cycloplegia at 20- and 30-minutes following proxymetacaine and cyclopentolate instillation in white 12-13-year-olds

CLINICAL RELEVANCE

Reducing the time between drop instillation and refraction reduces the time paediatric patients and young adults spend in practice, facilitating more eye examinations daily.

BACKGROUND

The current procedure for paediatric cycloplegic refraction is to wait for at least 30-minutes post-instillation of a cycloplegic before measuring spherical equivalent refraction. This study compared cycloplegia at 20- and 30-minutes following 0.5% proxymetacaine and 1.0% cyclopentolate in 12-13-year-olds.

METHODS

Participants were 99 white 12-13-year-olds. One drop of proxymetacaine hydrochloride (Minims, 0.5% w/v, Bausch & Lomb, UK) followed by one drop of cyclopentolate hydrochloride (Minims, 1.0% w/v, Bausch & Lomb, UK) was instilled into both eyes. Spherical equivalent refraction was measured by autorefraction (Dong Yang Rekto ORK-11 Auto Ref-Keratometer) at 20- and 30-minutes post-instillation. Data were analysed through paired t-testing, correlations, and linear regression analysis.

RESULTS

There was no significant difference in level of cycloplegia achieved at 20- (Mean spherical equivalent refraction (standard deviation) 0.438 (1.404) D) and 30-minutes (0.487 (1.420) D) post-eyedrop instillation (t (98) = 1.667, p = 0.099). The mean spherical equivalent refraction difference between time points was small (0.049 (0.294) D, 95% confidence interval =-0.108 ̶ 0.009D). Agreement indices: Accuracy = 0.999, Precision = 0.973, Concordance = 0.972. Spherical equivalent refraction at 20- and 30-minutes differed by ≤0.50D in 92% of eyes, and by <1.00D in 95%.

CONCLUSIONS

There was no clinically significant difference in spherical equivalent refraction or level of cycloplegia at 20- and 30-minutes post-eyedrop instillation. The latent time between drop instillation and measurement of refractive error may be reduced to 20 minutes in White 12-13-year-olds and young adults. Further studies must determine if these results persist in younger children and non-White populations.

Eye colour and skin pigmentation as significant factors for refractive outcome and residual accommodation in hypermetropic children: a randomized clinical trial using cyclopentolate 1% and tropicamide 1

PURPOSE

To compare the refractive outcome and residual accommodation with respect to various degrees of iris and skin pigmentation in hypermetropic children using 2 drops of cyclopentolate 1% (C + C) or 1 drop of cyclopentolate 1% and 1 drop of tropicamide 1% (C + T).

METHODS

Two hundred fifty-one hypermetropic children were classified according to iris and skin pigmentation (light, medium, dark) and received randomized and double-blind C + C or C + T. Refractive error (spherical equivalent, SEQ) was determined using the Retinomax-K + 3. In 204 subjects, residual accommodation (RA) was determined using the PlusoptiX PowerRefractor.

RESULTS

A linear mixed model with a light-irided and light skin-pigmented reference group receiving C + T (mean SEQ +3.10 ± 1.87D) indicated significant less hypermetropia in subjects with a dark iris having a medium- and dark-pigmented skin in C + T, -1.02 ± 0.29 (-1.59/-0.45) and -1.53 ± 0.30 (-2.10/-0.95); and in subjects having a light-, medium- and dark-pigmented skin in C + C, -0.74 ± 0.34 (-1.41/-0.06), -1.26 ± 0.30 (-1.85/-0.66) and -1.84 ± 0.30 (-2.42/-1.26). Similar findings were present for RA. Our model with a light-irided and light skin-pigmented reference group receiving C + T (mean RA +0.84 ± 0.61D) indicated significantly higher RA in dark-irided subjects with medium- and dark-pigmented skin in C + T, +1.05 ± 0.19 (+0.67/+1.43) and +1.35 ± 0.20 (+0.9/+1.74), and in C + C, +1.13 ± 0.21 (+0.71/+1.55) and +1.90 ± 0.19 (+1.51/+2.28).

CONCLUSIONS

We found solid evidence that skin pigmentation rather than iris pigmentation is the decisive factor for effectiveness of cycloplegics. Awareness of the limitations of cycloplegic regimens in dark-irided/pigmented children is needed. Our study showed that cyclopentolate 1% combined with tropicamide 1% provides more accurate refractive outcomes both statistically and clinically integrating the factor skin pigmentation for dark-irided subjects.

The effect of mydriasis from phenylephrine on corneal shape

PURPOSE

A previous study reported that pharmacologically-dilated pupils changed the corneal shape. Researchers used mydriatic agents with significant cycloplegic effect. The current study investigates the effect of mydriasis on corneal shape using phenylephrine alone, where phenylephrine has minimal effect on the accommodative system and whether corneal topography can be done after pupil dilation.

METHODS

Forty-four young healthy subjects with one eye randomly selected for mydriasis were used in this study. Twenty-two received one drop of 2.5% phenylephrine (group 1); the other 22 subjects had one drop of 0.4% benoxinate instilled prior to the application of 2.5% phenylephrine (group 2). They were matched for age and refractive error. Anterior chamber depth, pupil size and corneal parameters were compared before and after mydriasis. The corneal parameters included best-fit sphere (BFS), surface asymmetry index (SAI), surface regularity index (SRI) and the axial and tangential powers in the form of flattest and steepest powers, and in the form of M, J(0), and J(45) vector presentation.

RESULTS

Group 1 and group 2 subjects had similar pre-mydriatic baseline ocular parameters. The mean (+/- SD) pupil dilation was 1.24 +/- 0.59 mm for group 1 and 1.80 +/- 0.95 mm for group 2. The dilation was significantly larger in group 2 (unpaired t-tests: t = 2.36, p = 0.02). There were no significant changes in corneal parameters from mydriasis in either group.

CONCLUSIONS

Previous investigations used mydriatic agents, which affected not only the pupil size but also accommodation. The current study found that mydriasis from phenylephrine, with minimal effect on accommodation, did not result in significant corneal alteration, and corneal topography can be measured after pupil dilation with phenylephrine.

Adverse reactions to 1% cyclopentolate eye drops in children: an analysis using logistic regression models

PURPOSE

To determine the frequency, symptoms and risk factors for adverse reactions to two-times instillation of 1% cyclopentolate in children.

STUDY DESIGN

Prospective, observational study.

METHODS

The subjects were 646 patients who underwent cycloplegic refraction with cyclopentolate (mean age; 7.0 ± 3.5 years, age range; 0-15 years). Five minutes after instillation of 0.4% oxybuprocaine hydrochloride, a 1% cyclopentolate eye drop was instilled twice, with an interval of 10 min. Fifty minutes later, two certified orthoptists evaluated adverse reactions using a questionnaire and interviewed the patients' guardians. The relationship between the adverse reaction rates and age, gender, additional instillation, complications of the central nervous system (CNS), time of day and season were analysed using binominal and polytomous logistic regression models.

RESULTS

The overall frequency of adverse reactions was 18.3% (118/646 patients). The main symptoms included conjunctival injection (10.5%, 68/646), drowsiness (6.8%, 44/646) and facial flush (2.2%, 14/646). The odds ratio (OR) of conjunctival injection increased with patient's age (p < 0.05), in boys (p < 0.01) and in winter (p < 0.001). In contrast, the OR of drowsiness decreased with age (p < 0.001). Facial flush was observed mostly in children younger than 4 years. CNS complications were not a significant risk factor for any of the symptoms.

CONCLUSIONS

Adverse reactions to 1% cyclopentolate eye drops were more frequent than previously expected, but all were mild and transient. The probability of each symptom was associated with a clear age-specific trend.

Onset and duration of cycloplegic action of 1% cyclopentolate - 1% tropicamide combination

PURPOSE

To study the time course (onset, time and duration of maximal cycloplegia, and the full duration) of cycloplegic action of 1% Cyclopentolate - 1% Tropicamide.

METHODS

Seventy-seven students, aged 15-24 years were purposively sampled from the University of Cape Coast and Cape Coast Technical Institute. Subjective near addition (ADD) determination and pupil diameter measurement before and after a drop of the test agent (1% Cyclopentolate - 1% Tropicamide combination in the right eye) and the control (1% Cyclopentolate in the left eye) were performed. Measurements of subjective near ADD and pupil diameter were made after the initial reading at 5 minutes interval for the first hour and every 30 minutes for the next 7 hours for each participant. Time of onset, time of peak cycloplegia, duration of peak cycloplegia and duration of total cycloplegic effect was indirectly determined.

RESULTS

1% Cyclopentolate - 1% Tropicamide combination had rapid onset of cycloplegia (5-10 minutes), shorter time of maximal cycloplegia (55 versus 90 minutes), and recovery (7 versus ≥ 8hours) in the majority (79.2%) of subjects.

CONCLUSION

Cyclopentolate -Tropicamide combination was comparable to Cyclopentolate in depth of cycloplegia produced, and clinically superior to 1% Cyclopentolate in rapidity of cycloplegic onset, time of maximal cycloplegia and recovery from cycloplegia.