Evidence of Effect of Day Length Factor on Infantile Refractive Development: Multiple Regression Analysis-based Examination of Refractive Components of Cataracts.

Purpose: As the relationships between refraction and birth month suggest that day length factors affect the infantile refractive development, we aimed to prove the effect of day length factors by examining its evidence even among the elderly. Methods: We studied 1622 patients with cataracts (740 men and 882 women) who had preparatory measurements for corneal radius, axial lengths, and refractions for intraocular lens implantation. The day lengths for which each subject was exposed to from the first to eleventh month since birth were represented by variables DL1 to DL11. Similarly, absolute deviations from the yearly average of day lengths were represented by DDL1 to DDL11. We performed multiple regression analysis by substituting DL or DDL as explanatory variables for corneal radius, axial length, or refraction. Results: DLs were not relevant variables in elucidating corneal radius, axial length, and refraction. In contrast, DDLs were relevant variables in elucidating corneal radius (p<0.05). This association weakened for refraction and was not pertinent for axial length. Conclusion: Infantile refractive development is affected by the deviation in day length rather than the day length itself, evidence for which can still be observed among the elderly.

Inverse Analysis of the Relationship between Ocular Refraction and Birth Month Using Matrix Equations.

Purpose: To find which kind of light exposure and what sensitivity patterns in infancy influence the relationship between ocular refraction and birth month. Methods: We studied 13,757 children whose cycloplegic refraction could be tested during their initial visit to a children's hospital. After dividing subjects into four groups based on refractive degree, the risk ratio for each birth month was calculated from the cases for that month and the results were adjusted using the national birth/month. We then inversely assessed the risk ratio according to the birth month in each group using simply modeling matrix equations. Results: When results were calculated based on the possible effect of the day length, there was a wide variation in the degree of sensitivity depending on the number of months passed since birth at time of investigation, the statistical results falling into insignificant bimodal peaks. In contrast, when based on the assumption the effect was associated with deviations from the yearly average of the day length, far less variation was observed and there was a single natural sensitivity peak at around five months of age in all four refractive groups. Conclusion: Assuming that the peak stage of influence deviation from the yearly average of the day length has on the infant's refraction is at five month, there is a relationship between the refractive degree and the month of birth.

[Analysis of secular trends in proportion of students with poor visual acuity and the associated factors according to government statistics].

PURPOSE: Statistics obtained by the Japanese government were analyzed with the aim of elucidating the recent secular trends in proportion of students with poor visual acuity and the associated factors. METHODS: Data on the proportion of students with poor visual acuity were collected from the reports of the School Health Examination Surveys conducted from 1979 to 2012, and were graphically analyzed to detect a secular trend. We collected prefecture-level data regarding the visual acuity, body height, study time, sleeping duration, video-gaming duration, and duration of exposure to sunshine of sixth-grade students of elementary schools in all 47 prefectures in Japan. The relationship between poor visual acuity and other factors was explored by performing multiple regression analysis to identify the important predictors of poor visual acuity. RESULTS: A temporary retarding phase in the increasing tendency, as a halt in the growing tendency in terms of height, was observed in a proportion of students with poor visual acuity. Poor visual acuity was negatively correlated with duration of exposure to sunshine and was positively correlated with body height, but was only slightly correlated with study time and video-gaming duration. CONCLUSIONS: Because myopia is incriminated as the main cause of poor visual acuity, these results suggest that myopia progression would be influenced by the circumstances of exposure to light.

[Long-term changes in the ratio of exotropia to esotropia patients].

PURPOSE: To detect the long-term changes in the ratio of exotropia to esotropia in Japanese patients. METHODS: The published annual reports of 3 children's hospitals in Japan were reviewed with respect to the number of new patients diagnosed with either exotropia or esotropia. The yearly ratios of exotropia to esotropia were calculated from the past 30-year data. The ratios were analyzed by using regression analysis to determine the long-term variability. RESULTS: The ratio of exotropia to esotropia has increased in a parallel manner from less than 1.0 to nearly 2.0 in each of the 3 hospitals. CONCLUSIONS: This gradual increase in the ratio might be attributed to the increasing number of exotropic children who consult a doctor according to the level of development in health care, or might be the result of declining occurrence of accommodative esotropia along with the decreasing number of hyperopic children. Further studies are required to determine the reason for this tendency.

[Relationship between birth month and corneal radius or axial length].

PURPOSE: Hyperopia prevalence is higher in children born in the autumn. This study attempted to detect whether corneal curvature or axial length are related to this phenomenon. METHODS: Using data from a total of 4056 cataract patients aged 40 and over from three medical facilities, corneal radius and axial length, measured to determine the intraocular lens power needed for cataract surgery, were reviewed. Mean corneal radius and mean axial length were calculated for each birth month. The means were then graphically analyzed to determine the relationship of corneal radius or axial length with birth month. RESULTS: No correlation was noted between axial length and birth month. However, a correlation between corneal radius and birth month was observed in each of the three facilities. Specifically, subjects born from October through December tended to have larger corneal radii. Numerically, the corneal radius showed a statistical relationship in terms of birth month (p < 0.001, ANOVA), while the axial length showed no relationship (p = 0.907, ANOVA). CONCLUSION: A statistically meaningful relationship between corneal curvature and birth month was detected. Corneal development might be affected by seasonal daylight variations in infancy, thus contributing to the occurrence of hyperopia.

[Relationship between birth month and ocular refraction noted during eye disease checkups for three-and-a-half-year-old children in Japan].

PURPOSE: To examine the relationship between birth month and ocular refraction in three-and-a-half-year-old children. METHODS: A total of 487 children were examined during eye disease checkups performed in three-anda-half-year-old children in Kishiwada, Japan. Using left eye data, mean refractive values were calculated and graphically analyzed for each birth month. The relationship between refraction and birth season was evaluated by ANOVA. RESULTS: A slight shift in the mean refraction to the hyperopic side was found for subjects born in September and October. The mean refractions +/- SE were: -0.058 +/- 0.057 D in spring (n = 118), -0.001 0.052D in summer (n = 124), +0.133 +/- 0.064D in autumn (n = 112), and -0.143 +/- 0.055 D in winter (n = 111). Comparisons of refraction for each birth season proved to be significantly different, with subjects born in autumn found to be more hyperopic (p = 0.008). CONCLUSION: A relationship between refraction and birth season was found in three-and-a-half-year-old children, with children born in the autumn tending to be more hyperopic.

Surgical procedure for correcting globe dislocation in highly myopic strabismus.

PURPOSE: To design a surgical procedure for correcting globe dislocation in strabismus in high myopia (highly myopic strabismus). DESIGN: Prospective, interventional case series. METHODS: We examined 36 eyes of 21 patients with highly myopic strabismus and 27 eyes of 27 healthy volunteers as controls at Osaka City General Hospital between 2000 and 2006. Anatomic relationships between the muscle cone and globe were analyzed using magnetic resonance imaging. Ranges of globe movement and angles of ocular deviation were measured quantitatively as angles of maximum abduction and sursumduction and angles of ocular deviation, respectively, using the Goldmann perimeter and alternate prism cover tests. A surgical procedure involving muscle union of the superior rectus and lateral rectus muscles was performed in 23 eyes of 14 patients to restore the dislocated globe back to the muscle cone. RESULTS: After surgery, the angle of dislocation of the globe, defined as the angle formed by a line connecting the area centroid of the superior rectus muscle and the globe and a line connecting area centroid of the lateral rectus muscle and globe against the supertemporal wall of the orbit, was significantly decreased (P < .001), and angles of maximum abduction and sursumduction and the angle of ocular deviation improved significantly (P < .001). CONCLUSIONS: This surgical procedure to restore the dislocated globe back into the muscle cone by uniting muscle bellies of the superior rectus and lateral rectus muscles is effective for highly myopic strabismus.

An infant with idiopathic orbital myositis poorly responsive to steroid therapy: a case report.

A 9-month-old girl developed subacute limited adduction of the left eye, presenting with blepharoptosis. An orbital magnetic resonance imaging (MRI) 2 months after the onset revealed swelling of the left lateral rectus muscle, with increased intensity on T2-weighted images with fat saturation, which was enhanced with gadolinium. She was diagnosed with idiopathic orbital myositis based on history, physical examination, and MRI findings. Swelling of the left lateral rectus muscle was partially reduced by pulse steroid therapy. This is the first reported case of an infant orbital pseudotumor with clinical and MRI findings consistent with subacute orbital myositis. We propose that a fibrotic change of the orbital muscle may occur during a subacute course and would be incompletely responsive to steroid therapy.

Study of the visual evoked magnetic field with the m-sequence technique.

PURPOSE: Multifocally stimulated visual evoked magnetic field (VEF) examination with an m-sequence technique (multifocal VEF; mVEF) was studied, and the neural generators at peaks of mVEF were estimated in the visual cortex. METHODS: Visual field stimulation was generated by a multifocal testing system with use of the m-sequence technique. The stimulation pattern covered a central area extending from 0.6 degrees to 10 degrees in radius outward from the center of four visual-field quadrants. The stimulation pattern was projected onto a screen by a liquid crystal projector. VEFs of 14 healthy adults were recorded with a 160-channel, whole-head-type magnetoencephalography (MEG) system. The output signals of 16 selected MEG sensors covering the occipital region were recorded for each subject with the multifocal testing system, and the second-order responses were calculated. The analyzed response data files were transferred to the MEG system, a single equivalent current dipole (ECD) was estimated to locate the neural generator, and the localization was superimposed onto the corresponding brain magnetic resonance image of the subject. RESULTS: mVEFs showed three peak waves (N75m, P100m, N145m) in 75% of the subjects and two peak waves (N75m, N145m) in 25%. (N, P and m denote negative, positive, and magnetic fields, respectively.) Latencies of the first and the last peak were similar between the two kinds of peak waves. ECD examination showed more than 97% of goodness of fit at all peaks, and the relation between EDCs and the stimulated visual field coincided with a retinotopic organization that fit a cruciform model in all subjects. ECD depths from the occipital pole were similar to the depth expected from the human linear cortical magnification factor model in all subjects. Main neural generators of all mVEF components (N75m, P100m, N145m) were shown in the striate cortex (V1). CONCLUSIONS: Testing the VEF with an m-sequence technique showed stable responses to simultaneous stimulation of four visual-field quadrants. Consistency of correlation of the estimated ECD with the known cortical organization of the primary visual cortex confirmed the reliability of this examination. The three mVEF peaks were thought to derive mainly from V1 activity.