Time-Course of Changes in Choroidal Thickness after Complete Mydriasis Induced by Compound Tropicamide in Children

Long-term effect of orthokeratology on choroidal thickness and choroidal contour in myopic children

PURPOSE

To investigate the long-term effect of orthokeratology (ortho-k) on the choroidal thickness and choroidal contour in myopic children.

METHODS

Subjects were from a conducted 2-year randomised clinical trial. Children (n=80) aged 8-12 years with spherical equivalent refraction of -1.00 to -6.00D were randomly assigned to the control group (n=40) and ortho-k group (n=40). Optical coherence tomography images were collected at the baseline, 1-month, 6-month, 12-month, 18-month and 24-month visits, then the choroidal thickness and choroid contour were calculated. Axial length (AL) and other ocular biometrics were also measured.

RESULTS

During 2 years, in the control group, the choroidal thickness became thinning and the choroidal contour became prolate with time at all visits (all p<0.001). Ortho-k can improve the choroidal thickness (all p<0.001) and maintain the choroidal contour at all visits (all p<0.05). In the ortho-k group, the choroidal contour was less changed in the temporal than nasal (p=0.008), and the choroidal thickness was more thickening in the temporal 3 mm (p<0.001). Two-year change in choroidal thickness was significantly associated with the 2-year AL change in the control group (r=-0.52, p<0.001), however, this trend was broken by ortho-k (r=-0.05, p=0.342). After being adjusted by other variables in the multivariable regression model, the effect of ortho-k on choroidal thickness was stable.

CONCLUSIONS

In the current 2-year prospective study, ortho-k can improve the choroidal thickness and maintain the choroidal contour, but this effect diminished in a long term. Further study with larger sample size and longer follow-up is warranted to refine this issue.

Short-term anatomic response of the choroid to tropicamide in myopic patients

We aimed to investigate how tropicamide alters subfoveal choroidal thickness (SFChT) and choriocapillaris flow density (CD) and determine the predictive factors of choroid thickness and vascular density in myopic eyes. This retrospective study was conducted from September 2018 to March 2019. SFChT was measured with enhanced depth spectrum-domain optical coherence tomography. The choriocapillaris was imaged using optical coherence tomography angiograms. Ocular parameters were measured thirty minutes before and after 1% tropicamide instillation. Twenty-five eyes of 15 patients (mean age 38.12 ± 6.35 years old and refractive error-8.57 ± 3.37 D) met the study criteria. The baseline linear regression model showed an association of thinner choroid with older age (P = .027) and high myopic patients (P = .001). Tropicamide substantially increased SFChT (P = .001), but had no significant influence on CD (P = .526). Moreover, SFChT variation after tropicamide instillation positively correlated with diopter changes in spherical equivalent (P = .005) and percentage changes in CD (P = .046). In myopic eyes, choroidal layer thickened substantially in response to tropicamide. The increase of SFChT only correlates with variations in spherical equivalent and CD. Short-term tropicamide installation altered both choroid thickness and choroid microvasculature, which implies an interplay among choroidal volume, perfusion, and ciliary muscle tone.

Association between the posterior ocular contour pattern and progression of myopia in children: A prospective study based on OCT imaging

PURPOSE

This study aims to reveal the relationship between the posterior ocular contour and the subsequent progression of myopia in children.

METHODS

Children aged 8-12 years with myopia received baseline measurements and were instructed to wear their glasses every day and return for a follow-up visit after one year. Axial length and other ocular parameters were measured using a noncontact biometer. The contour of the posterior eye was calculated and analysed based on images from spectral domain optical coherence tomography (SD-OCT). Univariate and multivariate linear regression models were created to analyse the relationship between the contour of the posterior eye and the progression of myopia.

RESULTS

Baseline posterior ocular contour measurements correlated with baseline axial length and spherical equivalent refraction (SER) (all p < 0.05). Eyes that were more myopic tended to have a more prolate posterior ocular contour. Although the baseline contour of the retinal pigment epithelium (RPE) and chorioscleral interface (CSI) showed no significant relationship with the progression of myopia (all p > 0.05), interestingly, when the baseline contour of the RPE was more prolate than that of the CSI, the axial length increased during the following year (R²  = 0.62; p < 0.01). The multivariate model, when adjusted for other variables, further validated the independent role of this variable.

CONCLUSIONS

The difference between the RPE and CSI contours correlated with the subsequent progression of myopia in children. This finding can help inform clinicians regarding the management of children at the onset of myopia and potentially provide an avenue for experimental research on the mechanism of myopia development.

Adverse Cardiovascular Effects of Phenylephrine Eye Drops Combined With Intravenous Atropine

Background: Phenylephrine and atropine can cause serious adverse effects when applied in combination. We investigated the effect of phenylephrine eye drops combined with intravenous atropine on the cardiovascular system in patients under general anesthesia undergoing intraocular surgery. Methods: The effects of the drugs were observed through clinical study. Thirteen patients undergoing intraocular surgery under general anesthesia were observed in this study; all were injected intravenously with atropine due to the oculocardiac reflex during surgery. To study the combination of drugs, an in vivo study was performed on rats. Seventy-two standard deviation rats that received phenylephrine eye drops and intravenous atropine treatment under general anesthesia were assessed, of which 18 treated with these drugs simultaneously were administered normal saline, neostigmine or esmolol. Blood pressure and heart rate were recorded and analyzed. Findings: The age of the patients ranged from seven to 14 years old with an average age of 10.7 years old, and 11 patients were male. In patients, 5% phenylephrine eye drops combined with intravenous atropine led to a significant heart rate increase and the increase lasted 20 min. The significant increase in diastolic blood pressure and systolic blood pressure lasted for 15 and 25 min, respectively. From five to 25 min after intravenous atropine treatment, the systolic blood pressure and diastolic blood pressure were both more than 20% higher than that at baseline. In rats, the changes in blood pressure and heart rate were independent of the phenylephrine and atropine administration sequence but were related to the administration time interval. The neostigmine group showed a significant decrease in blood pressure after the increase from the administration of phenylephrine and atropine. Interpretation: Phenylephrine eye drops combined with intravenous atropine have obvious cardiovascular effects that can be reversed by neostigmine. This drug combination should be used carefully for ophthalmic surgery, especially in patients with cardio-cerebrovascular diseases.

Choroidal Thickness in Indigenous Australian Children

Purpose

This study aimed to examine the choroidal thickness profiles in visually normal Australian Indigenous children, given the important role of the choroid in refractive error and a range of ocular diseases.

Methods

Choroidal thickness was assessed across the central 5 mm macular region using enhanced depth imaging spectral domain optical coherence tomography, in 250 children enrolled in an elementary school and a secondary school in rural Queensland, Australia. One hundred (40%) of these children identified as Indigenous Australians.

Results

The subfoveal choroid was significantly thicker in Indigenous children (mean 369 ± 75 µm), compared to non-Indigenous children (355 ± 73 µm; P = 0.03). Subfoveal choroidal thickness was also significantly associated with age (β = +7.6, r² = 0.105, P = 0.003), and axial length (β = −19.9, r² = 0.030, P < 0.001). A significantly thicker choroid in Indigenous children was also found in analyses across the central 5 mm macular region (P = 0.008). A significant interaction between Indigenous status and meridian was observed (P = 0.007) with the largest differences between Indigenous and non-Indigenous children being in the nasal and inferonasal meridians.

Conclusions

This study establishes the normative characteristics of macular choroidal thickness in Indigenous Australian children and demonstrates a significantly thicker choroid compared to non-Indigenous children from the same geographic region. These results may have implications for our understanding of factors predisposing or protecting Australian Indigenous people from a range of conditions associated with choroidal thickness.

Translational Relevance

The significantly thicker choroid in Australian Indigenous children should be considered in clinical diagnoses and management of conditions associated with choroidal changes.

[Choroid and optical defocus]

The review summarizes experimental and clinical data attesting to the important role the choroid plays in the development of refraction through optically oriented thickness changes and the release of growth factors. Because of its unique anatomical position, the choroid can influence the transmission of a cascade of chemical signals from the retina to the sclera and thereby affect the growth of the eye. Understanding the relationship between the optical defocus and the response of the choroid to it will help uncover the fundamental mechanisms for controlling eye growth and develop new strategies for preventing the progression of myopia.

Short-term effects of atropine combined with orthokeratology (ACO) on choroidal thickness

PURPOSE

To analyse the one-month change in subfoveal choroidal thickness (SFChT) of myopic children treated with 0.01 % atropine, orthokeratology (OK), or their combination.

METHODS

This is a prospective, randomized controlled trial. One hundred fifty-four children aged between 8 and 12 years with a spherical equivalent (SE) of -1.00 to -6.00 diopters were enrolled. Subjects were randomly assigned to receive 0.01 % atropine and orthokeratology (ACO, n = 39), 0.01 % atropine and single vision glasses (atropine, n = 42), orthokeratology and placebo (OK, n = 36), or placebo and single vision glasses (control, n = 37). SFChT was assessed using optical coherence tomography (OCT). Ocular parameters, including axial length (AL), were measured using a Lenstar LS 900.

RESULTS

SFChT significantly increased in the ACO (14.12 ± 12.88 μm, p < 0.001), OK (9.43 ± 9.14 μm, p < 0.001) and atropine (5.49 ± 9.38 μm, p < 0.001) groups, while it significantly decreased in the control group (-4.81 ± 9.93 μm, p = 0.006). The one-month change in SFChT was significantly different between the control and treatment groups (p < 0.001). The results of pairwise comparisons among the treatment groups showed that the magnitude of the SFChT change was larger in the ACO group than in the atropine group (p = 0.002). The changes in the ACO and OK groups were not significantly different (p = 0.326).

CONCLUSION

The combination of OK and atropine induced a greater increase in SFChT than monotherapy with atropine, which might indicate a better treatment effect for childhood myopia control.

<p>Retinal Artery Contraction After Phenylephrine as a Cardiovascular Risk Biomarker</p>

Background and Aim

We investigated the in vivo changes of artery diameter (AD) and vein diameter (VD) after topical phenylephrine 2.5% instillation, and its relationship with the Systematic Coronary Risk Evaluation (SCORE).

Methods

This is a cross-sectional study. Healthy control patients were included. All of the participants underwent enhanced depth imaging by spectral-domain optical coherence tomography before and 30 minutes after phenylephrine instillation, using eye-tracking and follow-up software. Changes in AD and VD were assessed.

Results

The study included 45 eyes of 45 patients (14 males and 31 females). The mean age was 58.6 ± 15.1 years (26–88 years). Mean SCORE risk estimation value was 2.0 (0–14). No significant correlation was found between pre-phenylephrine AD or VD with age (p=0.237 and p=0.821, respectively), SCORE (p=0.545 and p=0.723, respectively). AD significant thinned after phenylephrine (p<0.001), whereas no significant changes could be depicted in VD (p=0.474). Changes in AD after phenylephrine were significantly related with SCORE risk estimation (p=0.035). Discordantly, changes in VD after phenylephrine were not significantly related with SCORE (p=0.505).

Conclusion

As a significant thinning of AD occurred following phenylephrine instillation, and as the magnitude of this thinning is related with SCORE, it is useful to test the retinal artery contraction to infer the cardiovascular health status.

Effect of Pupil Dilation with Tropicamide on Retinal Vascular Caliber

Purpose: The retinal blood vessels reflect changes in the brain's micro-circulation and these changes have been shown to correlate with the incidence of diseases such as stroke, heart disease and Alzheimer's disease. Studies investigating the retinal vasculature routinely use pupil dilation with tropicamide to optimize image acquisition and quality. The aim of this study was to investigate the effects of tropicamide on retinal vascular parameters using retinal photography.Methods: The study was performed on 41 healthy young subjects of both sexes, using tropicamide to dilate only the right pupil, leaving the left as a control.Results: Pupil dilation with tropicamide resulted in reduced retinal vessel width measures based on standardized approaches, particularly reduced arteriolar caliber (p < .0005). However, closer investigation of the images revealed reduced fundus image magnification in the post-tropicamide images, based on reduced optic nerve head diameter (p < .0005) and longitudinal analysis with image registration and affine transformation (p < .0001). No change in vessel width parameters was observed after adjustment for image magnification.Conclusion: These results suggest that tropicamide does not change the width of the retinal vessels, however width parameters as measured by standard approaches may be reduced due to image magnification changes resulting from cycloplegia. In this study, improved optic nerve head segmentation for image scale conversion removed the magnification error. With this correction, the tropicamide intervention had no effect on vessel width parameters in young healthy people and could be utilized in future without affecting the results of retinal vascular analysis.

Peripapillary and macular choroidal thickness before and after phenylephrine instillation

OBJECTIVES

We investigated the effects of topical phenylephrine 2.5% instillation on choroidal thickness (CT), peripapillary choroidal thickness (pCT) and retinal nerve fibre layer (RNFL).

METHODS

Healthy control patients underwent enhanced depth imaging (EDI) by spectral-domain optical coherence tomography (OCT) before and 30 min after phenylephrine instillation, using eye-tracking and follow-up software. Changes in 14 different locations of CT, 2 locations of pCT and RNFL were assessed.

RESULTS

The study included 119 eyes of 62 patients (19 males and 43 females), with a mean age of 59.8 ± 15.3 years (range: 26-88 years). Within 30 min after instillation, the mean subfoveal CT both in vertical and horizontal scan were significantly thinned (p = 0.005 and p  = 0.018, respectively). In total, 1500, 1000 and 500 µm temporal CT measurements showed also a significant thinning (p = 0.021, p  = 0.037 and p = 0.020, respectively), as well as 500 µm both superior (p  = 0.045) and inferior (p  = 0.009). 1500, 1000 and 500 µm nasal CT, and 1500 and 1000 µm CT superior and inferior measurements showed no significant thinning after phenylephrine instillation. pCT was significantly thinned after phenylephrine in both superior (p = 0.016) and inferior (p = 0.050) measurements. RNFL analysis did not significantly change after phenylephrine instillation (p =  0.209).

CONCLUSIONS

A significant thinning of CT and pCT occurred following phenylephrine instillation. Future studies analysing CT and pCT should detail if this mydriatic agent was used or not.

Change in subfoveal choroidal thickness secondary to orthokeratology and its cessation: a predictor for the change in axial length

PURPOSE

To investigate changes in subfoveal choroidal thickness (SFChT) during orthokeratology (Ortho-K) lens wear and after its cessation and the association of short-term change in SFChT with the long-term eye elongation in Ortho-K subjects.

DESIGN

A prospective clinical trial.

METHODS

Fifty myopic children aged between 9 and 14 years were enrolled. Twenty-nine subjects continuously wore Ortho-K lens for 12 months and discontinued for 1 month. Twenty-one subjects wearing single vision distance spectacles for 12 months were included as the control group. SFChT was assessed using optical coherence tomography. Ocular parameters, including axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT) and apical corneal power (ACP), were also measured.

RESULTS

After 12 months of follow-up, AL elongation was larger and SFChT change was smaller in the control group compared to the Ortho-K group (both p < 0.001). In the Ortho-K group, SFChT increased by 16 μm from baseline at the 1-month visit (p < 0.001), and the magnitude of choroidal thickening remained unchanged at the 6- and 12-month visit (p = 0.289). One month after discontinuation of Ortho-K lens, SFChT and ocular parameters of the anterior segment, including ACP, CCT and ACD recovered to baseline level (All p > 0.05), and AL increased by 0.23 ± 0.18 mm compared to baseline (p = 0.018). SFChT change at 1-month was negatively associated with AL change at 13-month (standard β, -0.581, p = 0.001) after adjusting for other influencing factors, including baseline age and the ocular parameters.

CONCLUSION

Subfoveal ChT (SFChT) significantly increased after short-term Ortho-K lens treatment and the increase maintained throughout the period of treatment. One month after Ortho-K lens cessation, SFChT, ACP, CCT and ACD returned to baseline. Short-term response in SFChT is associated with long-term change in AL in children undergoing Ortho-K lens and may be a predictor for the effectiveness of the treatment.

Choroidal thickness and axial length changes in myopic children treated with orthokeratology

PURPOSE

To analyze the change in subfoveal choroidal thickness (SFChT) and its relationship with changes in axial length (AL) in myopic children treated with Orthokeratology (Ortho-k).

METHODS

Fifty myopic children participated in this study: 29 subjects were treated with Ortho-k lenses and 21 with single vision distance spectacles. The SFChT and ocular biometrics, including AL, were measured at baseline, one month, and six months after lens wear in both groups.

RESULTS

AL significantly increased in both groups over time. In the Ortho-k group, SFChT also increased; however, there was no significant change in SFChT in the control group over time. At the six-month visit, the magnitude of eye growth was significantly reduced in the Ortho-k group compared to the control group (0.06±0.10mm vs. 0.17±0.10mm, P<0.001). SFChT was significantly thicker in the Ortho-k group compared to the control group at the one-month and six-month visits (15.78±11.37μm vs. -2.98±8.96μm, P<0.001 (one-month visit); 21.03±12.74μm vs. -2.50±14.43μm, P<0.001 (six-month visit)), although there was no significant difference between the two follow-up visits (P=0.102 for the Ortho-k group; P=0.898 for the control group). Changes in the large choroidal vascular layer (LCVL) accounted for the majority of subfoveal choroidal thickening (approximately 77% and 80% at one-month and six-month visits, respectively).

CONCLUSION

Ortho-k treatment induced significant choroidal thickening and a slowing of eye growth. LCVL thickening accounted for the majority of SFChT thickening. However, its potential mechanism in myopia control requires further investigation.

The effect of topical administration of cyclopentolate on ocular biometry: An analysis for mouse and human models

Mydriasis with muscarinic antagonists have been used routinely prior to retinal examination and sometimes prior to refractive measurements of the mouse eye. However, biometric changes during topical administration of muscarinic antagonists have not been fully investigated in mice and humans. We found that the mouse eyes treated with cyclopentolate developed a hyperopia with a reduction in both the vitreous chamber depth and axial length. In humans, prior to the cyclopentolate treatment, a 6D accommodative stimulus produced a myopic shift with a reduced anterior chamber depth, choroidal thickness and anterior lens radius of curvature and an increase in lens thickness. After the cyclopentolate treatment, human eyes developed a hyperopic shift with an increased anterior chamber depth and anterior lens radius of curvature and a reduced lens thickness. Therefore, the biometric changes associated with this hyperopic shift were mainly located in the posterior segment of the eye in mice. However, it is the anterior segment of the eye that plays a main role in the hyperopic shift in human subjects. These results further indicate that mouse eyes do not have accommodation which needs to be taken into account when they are used for the study of human refractive errors.

Correction: Time-Course of Changes in Choroidal Thickness after Complete Mydriasis Induced by Compound Tropicamide in Children

[This corrects the article DOI: 10.1371/journal.pone.0162468.].