Purpose: Watching three-dimensional (3D) images is known to induce ocular and non-ocular symptoms, such as eye discomfort, fatigue, headache, and nausea, which can be referred to as “3D asthenopia”. This study investigated ophthalmic factors associated with 3D asthenopia. Methods: One hundred fifteen volunteers, aged 18 to 55 years, were enrolled in this study. 3D images were shown to all volunteers with 3D high-definition television for 90 minutes. Subjects who felt eyestrain were assigned to the asthenopia group (14 subjects) and subjects without symptoms were assigned to the control group (22 subjects). Ophthalmic factors including visual acuity, refractive errors, interpupillary distance, intraocular pressure, tear break-up time, near point of accommodation, presence of strabismus, stereoacuity, and retinal abnormalities were evaluated and compared between the two groups. Results: Six subjects in the asthenopia group had exophoria and 1 subject in the control group had constant exotropia. None of these participants had previously noticed symptoms of strabismus. Only the presence of strabismus was significantly different between the groups ( P = .008). Conclusion: The presence of exophoria may be a risk factor for 3D asthenopia, and 3D television may induce asthenopia by exacerbating this latent problem.

To investigate surgical factors associated with the occurrence of oculocardiac reflex (OCR) and changes in heart rate (HR) during strabismus surgery. Patients who underwent strabismus surgery under general anesthesia were enrolled in this study. The HR during surgery was measured at baseline, and at the following points during surgery: traction of the muscle, maximal increase after traction (adrenergic phase), and the cutting of the muscle. OCR was defined as an HR reduction of more than 20% at traction of the muscle, when compared to baseline HR. The HR at each stage during the surgery was compared between patients with and without OCR. A total of 162 operated muscles from 99 patients were enrolled. The incidence of OCR was 65% in patients. In patients with two muscle surgeries, there were significantly more OCRs in the first operated muscle than in the second operated muscle (p < 0.01). The difference in the decrease in HR in patients with OCR was significantly lower than that in patients without OCR at traction of the muscle, the adrenergic phase, and the cutting of the muscle (all, p < 0.01). The first operated muscle was a significant risk factor associated with the occurrence of OCR (OR = 3.95, p < 0.01). The first operated muscle in patients with two muscle surgeries was a significant risk factor for OCR. Decreased HR at the traction of the muscle during surgery did not fully recover in patients with OCR.

Kim JH, et al. Korean J Ophthalmol. 2015 Apr;29(2):121-125. https://doi.org/10.3341/kjo.2015.29.2.121

Purpose: To evaluate the effect of classroom illuminance on the development and progression of myopia in elementary school children.Methods: The daylight factor, a ratio of inside and outside illuminance, was obtained in 50 elementary schools. The firstgrade students in the school with the lowest daylight (LD) factor (LD school, 145 subjects; 0.51%) and with the highest daylight (HD) factor (HD school, 147 subjects; 13.35%) were selected. A survey was conducted to evaluate parental myopia, the amount of near-work and outdoor activities. The refractive error and axial length (AL) were measured at initial and after 6 months. The spherical equivalent, AL, and the survey results were compared between the two schools. The mean AL of the emmetropic children was obtained, and all subjects were divided into two groups, more and less than mean AL. Changes in refractive errors and AL were also compared according to AL.Results: The amount of change in spherical equivalent and AL after 6 months were not different between the two schools. Initial prevalence of myopia was high in the HD school. However, it became similar between the two schools after 6 months. The mean AL of 155 emmetropic children was 22.7 ± 0.63 mm. In the 185 children with AL ≥22.7 mm, there was no difference in the AL change between the two schools. However, the change in AL in 107 children with AL <22.7 mm was significantly larger in the LD school (0.19 mm) than that in the HD school (0.15 mm, p = 0.049). Parental myopia, near-work and outdoor activities were not different between the two schools.Conclusions: High classroom illuminance during the day reduced axial elongation in eyes of children with a shorter AL. Increase in classroom light level by permitting more sunlight can be a protective measure against the development of myopia.