The effect of topical anti-muscarinic agents on subfoveal choroidal thickness in healthy adults

To investigate the effects of tropicamide and cyclopentolate, which are two anti-muscarinic agents commonly used in the ophthalmologic practice, on subfoveal choroidal choroidal thickness

(ChT) in healthy adults.

A total of 74 healthy adult subjects were enrolled in the study. Subjects were randomly divided into two groups: (1) cyclopentolate group (n=37) in which the right eye (study eye) of each

subject received topical cyclopentolate 1%, and the fellow eye (control eye) received artificial tears and (2) tropicamide group (n=37) in which the right eye (study eye) of each subject

received topical tropicamide 1% and the fellow eye (control eye) received artificial tears. Each topical medication was applied three times with 10-min intervals. ChT measurements were

performed at baseline and 40 min after the last drops of the topical medications by enhanced depth imaging (EDI) optical coherence tomography (OCT).

In the cyclopentolate group, subfoveal ChT significantly increased in the study eyes (P=0.013), whereas it did not significantly change in the control eyes (P=0.417). On the other hand, in

the tropicamide group, no significant subfoveal ChT changes were observed in either the study eyes (P=0.715) or the control eyes (P=0.344).

The current study demonstrated that cyclopentolate caused significant choroidal thickening, whereas tropicamide had no significant effect on ChT in healthy adults. As a result, mydriasis by

cyclopentolate may complicate ChT measurements by EDI OCT. Use of tropicamide may provide more reliable results for evaluation of ChT in ocular pathologies.

The choroid is the highly vascular layer of the eye placed between retina and sclera. It has several functions including procurement of oxygen and nutrients for the outer retina, adjustment

of retinal position, regulation of retinal temperature, protection of the photoreceptors, and secretion of some growth factors.1, 2 The introduction of enhanced depth imaging (EDI) optical

coherence tomography (OCT) technology by Spaide et al3 has provided accurate measurement of choroidal thickness (ChT) for investigating the in vivo anatomy of normal choroid and the

choroid-related ocular pathologies.

Previous studies by EDI OCT have shown that ChT is influenced by numerous ocular disorders including central serous chorioretinopathy, ocular tumors, age-related macular degeneration,

diabetic retinopathy, and inflammatory eye diseases.4, 5, 6, 7, 8 In addition, it is known that ChT is affected by various factors such as blood pressure, age, gender, time of the day,

refractive status, axial length, and forced hyperopic or myopic defocus.2, 9, 10, 11 Further, a recent experimental study showed that anti-muscarinic agents could affect ChT.12 Therefore, in

the present study, we aimed to investigate the effects of tropicamide and cyclopentolate, which are two anti-muscarinic agents commonly used in the ophthalmologic practice, on subfoveal ChT

measured by EDI OCT in healthy adults.

A total of 74 healthy adult subjects recruited from ophthalmology outpatient clinic were enrolled in the study. Subjects were randomly divided into two groups: (1) cyclopentolate group

(n=37) in which the right eye (study eye) of each subject received topical cyclopentolate 1%, and the fellow eye (control eye) received artificial tears and (2) tropicamide group (n=37) in

which the right eye (study eye) of each subject received topical tropicamide 1% and the fellow eye (control eye) received artificial tears. Each topical medication was applied three times

with 10-min intervals in both groups. Exclusion criteria were smoking, alcohol use, any ocular disorder reducing visual acuity, any ocular or systemic disorder that might affect ChT

measurement (ie, corneal scar, congenital cataract, glaucoma, strabismus, vitreoretinal disorders, diabetes mellitus), myopia or hyperopia ≥6 diopters (D), astigmatism ≥2 D, a history of

ocular trauma or surgery, age