Genome-Wide Association Study with Three Control Cohorts of Japanese Patients with Esotropia and Exotropia of Comitant Strabismus and Idiopathic Superior Oblique Muscle Palsy.

Esotropia and exotropia in the entity of comitant strabismus are multifactorial diseases with both genetic and environmental backgrounds. Idiopathic superior oblique muscle palsy, as the predominant entity of non-comitant (paralytic) strabismus, also has a genetic background, as evidenced by varying degrees of muscle hypoplasia. A genome-wide association study (GWAS) was conducted of 711 Japanese patients with esotropia (n= 253), exotropia (n = 356), and idiopathic superior oblique muscle palsy (n = 102). The genotypes of single nucleotide polymorphisms (SNPs) were determined by Infinium Asian Screening Array. Three control cohorts from the Japanese population were used: two cohorts from BioBank Japan (BBJ) and the Nagahama Cohort. BBJ (180K) was genotyped by a different array, Illumina Infinium OmniExpressExome or HumanOmniExpress, while BBJ (ASA) and the Nagahama Cohort were genotyped by the same Asian array. After quality control of SNPs and individuals, common SNPs between the case cohort and the control cohort were chosen in the condition of genotyping by different arrays, while all SNPs genotyped by the same array were used for SNP imputation. The SNPs imputed with R-square values ≥ 0.3 were used to compare the case cohort of each entity or the combined entity with the control cohort. In comparison with BBJ (180K), the esotropia group and the exotropia group showed CDCA7 and HLA-F, respectively, as candidate genes at a significant level of p < 5 × 10-8, while the idiopathic superior oblique muscle palsy group showed DAB1 as a candidate gene which is involved in neuronal migration. DAB1 was also detected as a candidate in comparison with BBJ (ASA) and the Nagahama Cohort at a weak level of significance of p < 1 × 10-6. In comparison with BBJ (180K), RARB (retinoic acid receptor-ß) was detected as a candidate at a significant level of p < 5 × 10-8 in the combined group of esotropia, exotropia, and idiopathic superior oblique muscle palsy. In conclusion, a series of GWASs with three different control cohorts would be an effective method with which to search for candidate genes for multifactorial diseases such as strabismus.

Analysis of temporal changes in thickness from conjunctiva to sclera after plication of the medial rectus muscle measured by anterior segment optical coherence tomography.

PURPOSE: We evaluated long-term changes in conjunctival bulge after medial rectus muscle (MR) tightening using the plication method. STUDY DESIGN: Retrospective and observational. METHODS: Patients who underwent MR plication for exotropia from December 2016-March 2020 at Okayama University Hospital were included. Thirty two eyes of 27 patients were enrolled. The thickness from the conjunctiva to sclera (TCS) at the limbus and insertion sites were measured using anterior segment optical coherence tomography preoperatively and 1 month, 4 months, and 12 months postoperatively. Correlations between the 1- and 12 month postoperative TCS and amount of MR tightening were analyzed. RESULTS: Preoperative and 4 month postoperative TCS at the limbus site were not significantly different (P=0.07). The 12 month postoperative TCS at the insertion site was significantly thinner than at 1 month postoperative (P<0.01), although significantly thicker than the preoperative TCS (P<0.01). No significant correlations were found between the amount of MR tightening (in mm) and 1- or 12 month postoperative TCS at the limbus (P=0.62 and P=0.98, respectively) and insertion (P=0.50 and P=0.24, respectively) sites. CONCLUSION: The TCS at the insertion site peaked at 1 month postoperatively, continued to decrease for longer than 4 months postoperatively, continuing until 12 months postoperatively. The TCS at the insertion site 12 months postoperatively is thicker than preoperatively. The TCS at both the limbus and insertion sites was not related to the amount of medial rectus muscle tightening.

Clinical Parameters Reflecting Globe/orbit Volume Imbalances in Japanese Acquired Esotropia Patients with High Myopia but without Abduction Limitations.

In high myopia, eye dislocation due to increased globe volume or tight orbital volume causes acquired esotro-pia. GOR (globe/orbit volume ratio), an indicator of the degree of progression of this pathology, was investi-gated the relationships among easily obtained clinical parameters. In this retrospective study, 20 eyes from 10 acquired esotropia patients with high myopia but without abduction limitations were examined. The mean age of the patients was 63.7 ± 8.2 years (mean ± standard deviation). Volumes were measured on the three-dimen-sional fast imaging employing steady-state acquisition magnetic resonance imaging images using the vol-ume-measurement function. Correlations between GOR and the displacement angle of the globe (DA), axial length (AL), and equatorial diameter (ED) were investigated. Mean DA, AL, ED, and GOR values were 107.5 ± 8.5°, 28.86 ± 1.92 mm, 25.00 ± 1.16 mm, and 0.36 ± 0.05, respectively. Only AL was correlated with GOR (p < 0.0001, R2 = 0.6649); DA (p = 0.30, R2 = 0.0633) and ED (p = 0.91, R2 = 0.0008) were not. AL was the only clinically available parameter to indicate globe/orbit volume imbalances in acquired esotropia with high myopia but without abduction limitation. AL may be important for the clinical assessment of the progression of this pathology.

Whole Exome-Sequencing of Pooled Genomic DNA Samples to Detect Quantitative Trait Loci in Esotropia and Exotropia of Strabismus in Japanese.

BACKGROUND: Esotropia and exotropia are two major phenotypes of comitant strabismus. It remains controversial whether esotropia and exotropia would share common genetic backgrounds. In this study, we used a quantitative trait locus (QTL)-sequencing pipeline for diploid plants to screen for susceptibility loci of strabismus in whole exome sequencing of pooled genomic DNAs of individuals. METHODS: Pooled genomic DNA (2.5 ng each) of 20 individuals in three groups, Japanese patients with esotropia and exotropia, and normal members in the families, was sequenced twice after exome capture, and the first and second sets of data in each group were combined to increase the read depth. The SNP index, as the ratio of variant genotype reads to all reads, and Δ(SNP index) values, as the difference of SNP index between two groups, were calculated by sliding window analysis with a 4 Mb window size and 10 kb slide size. The rows of 200 "N"s were inserted as a putative 200-b spacer between every adjoining locus to depict Δ(SNP index) plots on each chromosome. SNP positions with depth < 20 as well as SNP positions with SNP index of <0.3 were excluded. RESULTS: After the exclusion of SNPs, 12,242 SNPs in esotropia/normal group and 12,108 SNPs in exotropia/normal group remained. The patterns of the Δ(SNP index) plots on each chromosome appeared different between esotropia/normal group and exotropia/normal group. When the consecutive groups of SNPs on each chromosome were set at three patterns: SNPs in each cytogenetic band, 50 consecutive sliding SNPs, and SNPs in 4 Mb window size with 10 kb slide size, p values (Wilcoxon signed rank test) and Q values (false discovery rate) in a few loci as Manhattan plots showed significant differences in comparison between the Δ(SNP index) in the esotropia/normal group and exotropia/normal group. CONCLUSIONS: The pooled DNA sequencing and QTL mapping approach for plants could provide overview of genetic background on each chromosome and would suggest different genetic backgrounds for two major phenotypes of comitant strabismus, esotropia and exotropia.

Shape analysis of rectus extraocular muscles with age and axial length using anterior segment optical coherence tomography.

PURPOSE: This study aimed to evaluate the shape of the extraocular muscles (EOMs) in normal subjects using the en-face images of anterior segment optical coherence tomography (AS-OCT). The EOM insertion and the direction of the muscle fibers were investigated. SUBJECTS AND METHODS: A total of 97 healthy normal subjects (194 eyes) at Okayama University Hospital (age, 47.1±21.5 years; range, 8-79 years) participated in the study. A series of 256 tomographic images of the rectus EOMs were captured using the C-scan function of the AS-OCT (CASIA2, TOMEY Co., Japan), and the images were converted to en-face images in multi-TIFF format. The anterior chamber angle to EOM insertion distance (AID) and the angle of the muscle fibers from the insertion site (angle of muscles) were measured from the images. The correlations of AID and angle of muscles with age and axial length were investigated and evaluated. RESULTS: AID and angle of muscles were significantly correlated with age or axial length in some EOMs. The AIDs of medial rectus (MR) (P = 0.000) and superior rectus (SR) (P = 0.005) shortened with age. The AIDs of MR (P = 0.001) and inferior rectus (IR) (P = 0.035) elongated with axial length, whereas lateral rectus (LR) (P = 0.013) shortened. The angles of MR (P = 0.001) and LR (P = 0.000) were found to have a more downward direction toward the posterior in older subjects. CONCLUSION: En-face images can be created by AS-OCT, and the shape of the EOMs in normal subjects using these image measurements was available. With the ability to assess the EOMs, AID and angle of muscles are expected give useful information for treating and diagnosing strabismus-related diseases.

Formulas to Estimate Appropriate Surgical Amounts of Unilateral Recession-Resection in Intermittent Exotropia with Distance-Near Disparity.

The purpose of this study was to derive new formulas to provide an optimal surgical procedure and optimal amount of recession-resection (RR) surgery in intermittent exotropia (IXT) with a disparity in angle of deviation depending on the fixation distance. The records of 117 consecutive patients with IXT who underwent RR surgery between March 2008 and December 2011 at Okayama University Hospital were retrospectively examined. Multivariable linear regression analysis was performed using the observed corrective angle of deviation at distance or near fixation as the dependent variable, and amounts of lateral rectus muscle (LR) recession (mm) and medial rectus muscle (MR) resection, and age at surgery (years) as independent variables. Two simultaneous formulas were derived: corrective angle of deviation at distance fixation (°)=1.8×recession (mm)+1.6× resection (mm)+0.15×age (years)-6.6, and corrective angle at near fixation (°)=1.5×recession (mm)+1.7× resection (mm)+0.18×age (years)-3.8. Comparisons of coefficient values of the formulas between distance and near fixation revealed that LR recession was more affected by the corrective angle in distance than near fixation. MR resection was more affected at near than distance fixation. We found that our new formulas estimated the appropriate amount of unilateral RR surgery.

Risk factors for excessive postoperative exo-drift after unilateral lateral rectus muscle recession and medial rectus muscle resection for intermittent exotropia.

BACKGROUND: To detect significant factors associated with excessive postoperative exo-drift in young patients with intermittent exotropia who had undergone unilateral lateral rectus muscle recession and medial rectus muscle resection. METHODS: We retrospectively examined the records of 64 consecutive patients < 18 years old who underwent surgery between April 2004 and December 2011. We sought risk factors for excessive postoperative exo-drift among patients' demographic and clinical characteristics using univariate and multivariable linear regression analysis. RESULTS: Younger patients (P = 0.007), and those with larger preoperative exo-deviation at distance (P = 0.033), a lower incidence of peripheral fusion at distance (P = 0.021) or a greater postoperative initial eso-deviation (P = 0.001), were significantly more likely to have an excessive postoperative exo-drift (> 20 prism diopters). Univariate analysis revealed significant associations between excessive postoperative exo-drift and age at surgery (P = 0.004), preoperative exo-deviation at distance (P = 0.017) and postoperative initial eso-deviation at distance (P < 0.001). Multivariable linear regression analysis showed that postoperative initial eso-deviation at distance (P = 0.008) was significantly associated with postoperative exo-drift. CONCLUSIONS: Postoperative exodrift in unilateral RR is predicted by the initial postoperative eso-deviation, which may offset the overcorrection. However, the exo-drift is greater in cases with a large preoperative exo-deviation and/or at a younger age, and should be followed carefully.

Twist Knot: A New Sliding Noose in Adjustable Suture Strabismus Surgery.

To permit noose movement without fraying the sutures following strabismus surgery, we designed a new sliding noose, the "twist knot" and investigated its advantages and disadvantages. We measured the tensile strength required to move the twist knot in a tightly tied state (134±19 gf) and in a loosened state (21±7 gf), and that required to move the conventional sliding noose in a tightly tied state (48±14 gf), and used the Kruskal-Wallis test to compare them. A significant difference was observed among the three tensile strengths (p<0.001). The twist knot technique allowed easy sliding without the multifilament braided suture becoming frayed and a knot to be firmly fixed without slipping. However, if the 2 strings of the pole sutures exit from the sclera at 2 widely separated positions, the sliding noose may become slack. Therefore, the distance between the pole sutures should be small. The simple twist knot technique was found to be an effective approach following adjustable surgery of strabismus.

Lights-out Surgery for Strabismus Using a Heads-Up 3D Vision System.

During strabismus surgery using illumination from a light source, patients complain of photophobia. The NGENUITYⓇ (Alcon) system is equipped with a high-dynamic-range (HDR) camera. A 4K display viewed by wearing circularly polarized glasses provides clear three-dimensional images of the operative field. A light source is usually required for surgeries of the anterior segment (including strabismic surgery), but the digital processing function of the NGENUITYⓇ system allows image display in relatively dark regions even without a light source. We devised a novel 'lights-out' surgery that does not use a microscope's light source, and we examined the usefulness of this technique in 2 cases of strabismic surgery. We performed strabismus surgery using the NGENUITYⓇ system in two patients between January and June 2018. The HDR function was used, and the aperture was opened to the maximum while the gain was adjusted. Surgery was conducted without using the microscope's light source. We report the 2 cases' results and evaluate the novel method. The surgeries were performed without problem even though the microscope's light source was not used. The patients' photophobia was alleviated. Lights-out surgery is a potentially useful modality for strabismus surgery.

Congenital Multiple Ocular Motor Nerve Palsy Complicated by Splitting of the Lateral Rectus Muscle.

We report a case of congenital multiple ocular motor nerve palsy combined with splitting of the lateral rectus muscle (LR). A 59-year-old Japanese female was investigated for worsening esotropia after corrective surgery. She presented with left hypertropia (35Δ) and esotropia (45-50Δ). Orbital magnetic resonance imaging (MRI) showed reduced belly sizes in the superior rectus, inferior rectus, and superior oblique muscles and splitting of the LR, extending from the origin to the belly, in the left eye. Splitting of the LR belly was detected on MRI in a case of congenital multiple ocular motor nerve palsy.

Magnetic resonance imaging findings of age-related distance esotropia in Japanese patients with high myopia.

PURPOSE: This study aimed to investigate the characteristics of the extraocular muscles and the orbital connective tissue pulleys in Japanese patients with age-related distance esotropia (ARDE) and high myopia using magnetic resonance imaging (MRI). METHODS: This was a retrospective case-series study. High-resolution coronal MRI scans of 12 orbits were obtained in 6 patients with ARDE and high myopia (age range: 51-69 years). We analyzed the images to determine the positions of the rectus muscle pulleys relative to the center of the globe, the integrity of the lateral rectus-superior rectus muscle (LR-SR) band, and the LR angle (the angle between the major axis of the LR and the vertical plane). RESULTS: The distance esotropia ranged from 4 to 25∆, and 3 cases exhibited vertical deviations. The mean (±standard deviation (SD)) axial length was 28.5 (± 1.6) mm. The mean positions of the medial rectus muscle pulley and LR pulley were 1.3 mm inferior and 1.4 mm inferior, respectively, to those seen in the normal control group in our previous study (P = 0.002 and P = 0.05, respectively). All 12 orbits had abnormal elongated LR-SR bands, and 8 orbits (67%) displayed ruptured LR-SR bands. The LR angle (mean±SD; 18.8° ± 8.5°) increased significantly with the inferior displacement of the LR pulley (R2 = 0.77, P = 0.0002). CONCLUSIONS: Inferior displacement of the LR pulley and abnormal LR-SR bands were seen in Japanese ARDE patients with high myopia, as was found in ARDE patients without high myopia. The LR angle might be useful for judging the degree of LR pulley displacement.

Differences in the Stability and Amount of Postoperative Exodrift with Age after Unilateral Lateral Rectus Muscle Recession and Medial Rectus Muscle Resection of Intermittent Exotropia.

We investigated variances in the stability and amount of postoperative exodrift among age groups of intermittent exotropia (XPT) patients who underwent unilateral lateral rectus muscle recession and medial rectus muscle resection. We analyzed the cases of 110 consecutive patients who underwent the surgery in 2004-2011, dividing the patients into groups by their age at surgery: <10, 10-19, and ≥20 years. We performed a regression analysis (dependent variable: postoperative exodrift (°); independent variable: number of days post-surgery) using the formula of curve lines. When the tangent line slope was = 0.01 (°/days) for each group, we defined the numbers of days until alignment became stable as the 'stable days.' We evaluated the between-group differences in the amount of exodrift calculated for the stable days. The coefficients and coefficients of determination for the fitting curves were: <10 year group: f(x)=12.2 (1-e-0.0183x) (r2=0.588, p<0.05); 10-19 year group: f(x)=10.0 (1-e-0.0178x) (r2=0.453, p<0.05); ≥20 year group: f(x)=3.40 (1-e-0.0382x) (r2=0.217, p<0.05). There were 389 , 388, and 153 stable days, and the estimated postoperative exodrift with long-term follow-up was 11.5±3.7°, 9.3±4.4°, and 4.1±3.6° for the < 10 year, 10-19 year, and ≥ 20 year groups, respectively (≥20 year vs. other 2 groups, p<0.05). Longer periods and more postoperative exodrift were associated with younger age at surgery. The postoperative evaluation was approx. ≥ 1 year post-surgery in patients aged < 20. These findings may contribute to evaluating XPT's success rate and prognoses.

Predictive factors for corrective effect of inferior rectus recession for congenital superior oblique palsy.

PURPOSE: To identify preoperative factors associated with the surgical corrective effect of contralateral inferior rectus recession (IRR) for vertical deviation in patients with congenital superior oblique palsy (SOP). METHODS: This retrospective study included 20 treatment-naïve patients with unilateral congenital SOP (age range, 6-79 years) who underwent contralateral IRR according to our basic policy to select IRR for paretic eye fixation. The corrective effect (°/mm) of IRR was defined as the difference in the vertical deviation at the primary gaze position between before and 6-18 months after surgery per distance of recession. We also measured the preoperative vertical deviation at primary and secondary gaze positions, and vertical deviation with head-tilting, and calculated the difference in vertical deviation between these positions. We analyzed the correlation between the corrective effect of IRR and these study parameters. RESULTS: The mean corrective effect of IRR was 2.4 ± 1.6°/mm, which had a significant correlation with preoperative differences in vertical deviation between the primary gaze position and the downward (P = 0.004, r = -0.61) and contralateral gaze positions (P = 0.03, r = -0.48); and the presence of preoperative stereopsis (P = 0.02, r = -0.51). After excluding a statistical outlier, the correlation between the corrective effect and the difference between the primary and contralateral gaze positions was no longer significant (P = 0.07), while the other two relationships remained significant. CONCLUSIONS: Our findings suggest that preoperative differences in vertical deviation between the primary and downward gaze positions and the presence of preoperative stereopsis are important considerations prior to performing IRR for congenital SOP, particularly with paretic eye fixation.

Quantitative Analysis of the Effects of a Bangerter Filter on Gross Stereopsis in Experimental Models of Reduced Visual Acuity.

Although a 0.3 Bangerter filter, which reduces visual acuity, is frequently used for treating moderate amblyopia, the effects on gross stereopsis are not well known. This study quantitatively evaluated whether gross stereopsis is degraded by a Bangerter filter. Seven healthy subjects (median age: 29 years) participated in this psychophysical study. Targets with crossed disparities of 1°, 2°, 3°, 4°, and 5° were randomly presented on a three-dimensional television display. The subjects indicated the point at which the targets popped out from the television screen (matching method). The distance from the screen to the point was defined as the degree of stereopsis. This experiment was performed with and without a 0.3 Bangerter filter. The corrected monocular visual acuities were decreased to about 20/63 by the filter in all subjects. No significant difference was observed for any of the disparities (1°-5°), between the degree of stereopsis visualized with and without filters for either the dominant or the non-dominant eye. The degree of stereopsis was not degraded by the reduced visual acuity induced by the use of 0.3 Bangerter filters. In this regard, the use of 0.3 Bangerter filters may be considered safer than occlusion eye patches for the patients with normal binocular vision.

Clinical factors underlying a single surgery or repetitive surgeries to treat superior oblique muscle palsy.

The purpose of this study is to know clinical factors underlying either a single surgery or repetitive surgeries, required to treat superior oblique muscle palsy. Retrospective review was made on 246 consecutive patients with idiopathic (n = 212) or acquired (n = 34) superior oblique muscle palsy who underwent surgeries in 8 years at one institution. Idiopathic palsy included congenital and decompensated palsies while acquired palsy included traumatic and ischemic palsies. Clinical factors, compared between groups with a single surgery (n = 203) and two or more surgeries (n = 43), were surgical methods, sex, age at surgery, horizontal, vertical, and cyclotorsional deviations, and stereopsis at near fixation. Inferior oblique muscle recession on paretic side was chosen in about 60% of the single-surgery and repetitive-surgery group as an initial surgery, followed by inferior rectus muscle recession on non-paretic side. The age at surgery was significantly older, vertical and cyclotorsional deviations were significantly larger in the repetitive-surgery group, compared with the single-surgery group (P = 0.01, P < 0.001, P = 0.02, Mann-Whitney U-test, respectively). The 95% confidence interval of vertical deviations was 15-17 prism diopters in the single-surgery group and 23-28 prism diopters in the repetitive surgery group. Significant differences in vertical deviations were replicated also in subgroups of patients with either idiopathic or acquired palsy. In conclusions, the 95% confidence interval of vertical deviations, determined by alternate prism and cover test, would be used as a common benchmark for predicting either a single surgery or repetitive surgeries, required to treat idiopathic and acquired superior oblique muscle palsy, in the process of obtaining the informed consent.

Outcome of conventional treatment for adult amblyopia.

PURPOSE: To ascertain whether conventional treatment can improve visual function in adults with amblyopia. METHODS: Sixteen patients aged 21-67 years old were instructed to wear glasses for refractive correction and to patch the non-amblyopic eye for at least 1 h per day. Visual acuity, measured with crowded optotypes for distance and near acuity, was checked every 3 months, and followed for a mean (SD) of 14.1 (4.2) months. Prognostic factors related to the subsequent results, an improvement of 3 or more lines logMAR in distance visual acuity, were evaluated. RESULTS: Of 16 patients, 5 (31 %) improved 3 or more lines of distance and 5 (31 %) in near acuity. The mean improvement in distance was 2.4 lines logMAR (95 % CI 1.4-3.5) and 2.4 lines logMAR for near acuity (95 % CI 1.5-3.3). Patients aged under 45 years (p = 0.0357) and with severe amblyopia (p = 0.0337), defined as a corrected distance visual acuity of worse than -0.699 logMAR, were associated with a good response. CONCLUSIONS: Conventional treatment may improve the visual acuity of amblyopic eyes even in adult patients.

Effects of vertical muscle surgery on differences in the orientation of Listing's plane in patients with superior oblique palsy.

BACKGROUND: Although scleral search coils are widely and accurately used for the measurement of Listing's plane in both eyes, they require specialized equipment and are invasive. In this study, we describe a convenient and less invasive method that uses a synoptometer to analyze the differences in orientation of Listing's plane (difLP), and the effects of vertical muscle surgery on the difLP tilt in patients with superior oblique palsy (SOP). METHODS: Seventeen patients with unilateral congenital SOP (CSOP) and four patients with unilateral acquired SOP (ASOP) who had not undergone any strabismus surgeries were examined. Cyclodeviations of 13 vertical and horizontal gaze points within 30° were measured with a synoptometer, and the difLP tilts in the yaw and pitch planes were analyzed before and after vertical muscle surgery. RESULTS: The difLP tilt in the CSOP patients was significantly tilted nasally (p = 0.02) and forward on the lower side (p = 0.001), whereas that in ASOP patients tended to tilt temporally (p = 0.15). Ipsilateral inferior oblique recession (IOR) performed in seven CSOP patients tended to improve the difLP tilt in both the yaw (p = 0.07) and pitch (p = 0.09) planes, whereas contralateral inferior rectus recession (IRR) performed in three CSOP patients significantly improved the difLP tilt in the pitch plane (p = 0.015). The mean excyclodeviations in the 13 gaze points were significantly improved with both procedures (p < 0.0001 for both). CONCLUSIONS: The difLP tilt in the SOP patients could be analyzed with a convenient and less invasive method using a synoptometer, and dissimilar difLP tilts were confirmed in the ASOP and CSOP patients. The results of this study suggest that both IOR and IRR are reasonable treatments for improving the difLP tilt in CSOP patients. IOR should be selected for patients with a steep preoperative difLP tilt to the nasal side, whereas IRR should be selected for patients with a gentle preoperative difLP tilt.

Vertical alignment in monkeys with unilateral IV section: effects of prolonged monocular patching and trigeminal deafferentation.

We investigated monocular viewing and trigeminal (V) deafferentation on the vertical deviation (VD) in monkeys following intracranial IV section. Two monkeys wore a patch for four to six weeks, one over the paretic eye and the other over the normal eye following IV section. Two other monkeys had combined IV and V section with the paretic eye patched postlesion. In monkeys with IV section alone, the VD lessened within the first week postlesion but then increased gradually with the same eye still patched. Thus binocular viewing was unnecessary for the later VD increase. With combined IV and V section, the VD also transiently lessened postlesion. We have proposed that the decrease in VD after IV section is adaptive, driven by an error signal using ocular proprioception and efference copy. Since V section did not eliminate the early decrease in VD, we suggest some orbital afference is transmitted centrally via other cranial nerves. However, the later increase in VD suggests either that the proprioceptive effect cannot be sustained or that mechanical changes supervene to increase the VD.

Relationship between static ocular counterroll and Bielschowsky head tilt phenomenon.

PURPOSE: This study was conducted to assess how hyperdeviation of a paretic eye during ipsilesional head tilt-the Bielschowsky head tilt phenomenon (BHP)-can be explained by decreased compensatory ocular counterrolling (OCR) due to the depressed torque of the paretic superior oblique (SO) muscle. METHODS: Thirty-three patients with clinically diagnosed SO palsy and 11 control subjects were studied. With a head-mounted video camera, static ocular counterrolling (s-OCR) was determined by measuring the inclination of a line connecting the two centroids of the characteristic iris pattern and corneal reflex. The BHP was measured with the alternate prism and cover test. RESULTS: The mean (SD) amplitude of s-OCR in paretic eyes based on the fit of the regression sine curve against the ipsilesional head tilt angle was significantly decreased compared with that for contralesional head tilt, 6.3 (3.5) degrees for ipsilesional and 11.3 (3.9) degrees for contralesional (P < 0.001), and was significantly smaller than that in normal subjects: 10.9 (2.6) degrees (P < 0.001). No significant linear relation was noted between hyperdeviation on ipsilesional head tilt and the amplitude of s-OCR in paretic eyes (r(2) = 0.04; P = 0.29). However, the differences between the hyperdeviation with ipsilesional 30 degrees head tilt and with head-upright position correlated significantly with the amplitudes of s-OCR in paretic eyes (r(2) = 0.19, P = 0.01). CONCLUSIONS: The absolute value of the hypertropia on ipsilesional head tilt in clinically diagnosed SO palsy does not directly assess the function of the SO muscle. The difference in hypertropia between ipsilesional head tilt and the upright position, however, may be a better indicator of SO function.

Effect of progressive addition lenses on myopia progression in Japanese children: a prospective, randomized, double-masked, crossover trial.

PURPOSE: This prospective, randomized, double-masked, crossover trial was conducted to evaluate the clinical effectiveness of progressive addition lenses (PALs) compared with single-vision lenses (SVLs) on myopia progression in Japanese children. METHODS: Ninety-two children fulfilling the inclusion criteria (age: 6-12 years, spherical equivalent refractive errors: -1.25 to -6.00 D) were randomly allocated to either 18 months of wearing PALs (near addition: +1.50 D) followed by 18 months of SVLs (group 1), or 18 months of wearing SVLs followed by 18 months of wearing PALs (group 2), and were followed up for 3 years (two-stage crossover design). The primary outcome measure was myopia progression, as determined by cycloplegic autorefraction. RESULTS: Eighty-six (93%) children completed both treatment periods. A mixed-model, two-way analysis of variance (ANOVA) performed using 3-year data identified a significant treatment effect of PALs compared with SVLs (P = 0.0007), with a mean 18-month difference of 0.17 D (95% CI: 0.07-0.26 D). This analysis also indicated a significant period effect (P = 0.0040) and a significant treatment-by-period interaction (P = 0.0223): Group 1 showed a slower myopia progression than did group 2. CONCLUSIONS: The use of PALs slowed myopia progression, although the treatment effect was small, as previously reported in ethnically diverse children in the United States. The significant treatment-by-period interaction suggests that early application of PALs would probably be more beneficial for these age and refraction ranges (isrctn.org number, 28611140).