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Objective: To explore the ultrastructural alteration of extraocular muscle proprioceptor in congenital idiopathic nystagmus (CIN). Methods: Case-control study. Ten extraocular muscle samples were collected from five CIN children who underwent nystagmus surgeries in Beijing Children's Hospital from March 2015 to March 2016. Another ten extraocular muscle specimens were collected from five strabismus children in surgery at the same period as normal contrast. There were 3 male patients and 2 female patients of CIN with age of 61-147 months (median age: 91 months). The ultrastructure of extraocular muscle proprioceptors was compared between these two groups by transmission electron microscope. Results: Twenty-three proprioceptors were found in extraocular muscle specimens of CIN children, whereas thirty-three proprioceptors were detected in strabismus children. The ultrastructure of extraocular muscle proprioceptor of CIN altered greatly comparing with that of the control. Fourteen extraocular muscle proprioceptors of CIN were discovered much smaller and vacuolated not only at inner capsules but also at the space between inner and outer capsules with lipofuscins and myeloid bodies in the intrafusal muscle fibers. Sensory nerve fibers degenerated greatly with a lot of lipofuscins and myeloid bodies in these sensory nerve fibers. Demyelination also appeared in some severe cases. Nine extraocular muscle proprioceptors of CIN showed significant dissolving degeneration of myofibrils and proliferation of collagen fibrils. The normal structures could not be distinguished in these proprioceptors. And these structural disorders also appeared in extrafusal muscle fibers and nerve endings. Conclusion: The ultrastructure of extraocular muscle proprioceptor in CIN turned much smaller and had significantly structural disorder. (Chin J Ophthalmol, 2017, 53: 136-139) .

Objective: To offer a clue for the etiology of amblyopia by systematically comparing the macular thickness measured by optical coherence tomography (OCT) between the amblyopic eye and the fellow normal eye in patients with unilateral amblyopia., Methods: Databases including Wanfang, PubMed and others were searched, and data were extracted after quality assessment, then the Meta analysis was performed by the RevMan 5.02 software., Results: Four studies using the time-domain OCT (TD-OCT) were enrolled in the analysis and all those were anisometropic amblyopic patients. The only one study showed that the foveal minimum thickness is thicker in the amblyopic eyes than the fellow ones (P = 0.045). The meta analysis indicated the amblyopic eyes were 6.82 µm (P < 0.05, 95% CI: 2.81-10.83) thicker in the fovea (1 mm diameter region ). Five trials using the spectral-domain OCT (SD-OCT) were included in the analysis. It showed no significant difference in the foveal minimum thickness between amblyopic and fellow eyes. Also, no significant difference were detected in either anisometropic or strabismic subgroup (P = 0.50). Amblyopic eyes were 7.38 µm thicker in the fovea (1 mm diameter region) (P < 0.05, 95% CI: 3.13 -11.63) and significant difference in the anisometropic subgroup while no significant difference in the strabismic subgroup were detected., Conclusions: The macular fovea is thicker in the amblyopic eyes than the fellow ones by the use of OCT, so it is effective to measure the macular thickness of amblyopia in searching evidence for the etiology of amblyopia.

Objective: To evaluate the application of relative reference point photographic analysis method and goniometer method for head posture measurement, and compare the characteristics of the two methods., Methods: Thirty patients from March 2011 to April 2011 and August to September with AHP in our hospital were recruited. The AHP were measured by photographic analysis and goniometer method respectively. The data were analyzed by SPSS software., Results: The mean AHP was 15.62° ± 7.48° by photographic analysis measurement, 15.50° ± 6.99° by goniometer measurement. The Pearson's correlation coefficient (r = 0.955, P < 0.001, t = 0.286, P = 0.777)., Conclusions: Relative reference point photographic analysis is a simple and effective way to measure AHP. The results measured by the two methods are highly consistent.

Objective: To study the neural mechanism of visual cortical deficits between anisometropic and strabismic amblyopia comparatively by BOLD-fMRI retinotopic mapping., Methods: Ten anisometropic amblyopes, 10 strabismic amblyopes and 9 normal subjects underwent fMRI with retinotopic mapping and luminous spots stimuli (spatial frequency: 6 cpd, contrast: 0.5). 1.5T MRI system was used to obtain functional images of visual cortex. Responses in primary and secondary visual cortex were compared among the dominant (normal subject group), anisometropic and strabismic amblyopic eyes by one-way ANOVA, successively analyzed by paired-samples t test between amblyopic eyes and fellow fixing eyes (anisometropic and strabismic amblyopia group respectively). Their fMRI deficits of amblyopes were analyzed regressively in two amblyopia groups respectively., Results: The result of one-way ANOVA showed significantly a lower activation (average T value) in V1, V2, V3, Vp and V7 visual areas (P < 0.05, P values 0.018, 0.007, 0.002, 0.000, 0.025 respectively) between anisometropic amblyopia and normal group. This was in accordance with the result of paired-samples t test between amblyopic eyes and fellow fixing eyes in anisometropic amblyopia group (P < 0.05, P values 0.035, 0.007, 0.020, 0.009, 0.023 respectively). Statistical difference was found in V1, V2 and Vp areas between strabismic amblyopia and normal group (P < 0.05, P values 0.010, 0.007 & 0.003 respectively). The paired-samples t test in strabismic amblyopia group showed statistical difference only in V2, Vp areas (P < 0.05, P values 0.026 and 0. 009 respectively. ). So the two results were discordant. Between the two amblyopic groups, there was no statistical difference (P > 0.05) except in V7 area (P < 0.05, P value = 0.048). There was no causal relation between the primary visual cortical deficits and the secondary cortex in amblyopia (P > 0.05)., Conclusion: Anisometropic amblyopia and strabismic amblyopia both have functional deficits in the primary and secondary visual cortex. The neural mechanism of secondary visual cortical deficits may be more complex than decreased cortex activation induced by the deficit of primary cortex. In the primary cortex, strabismic amblyopia and anisometropic amblyopia have neuronal deficits and/or abnormal interaction. In addition, strabismic amblyopia may also have suppressive influences of the fixing eyes upon the amblyopic eyes. Anisometropic amblyopia has the neural undersampling at a high spatial frequency in the secondary visual cortex as compared to amblyopic amblyopia.

The advent of magnetic resonance imaging (MRI) has given us previously unavailable opportunities to visualize the functional anatomy of extraocular muscles and corresponding ocular motor nerves along the intraorbital and intracranial course of living subjects. Ophthalmologists should be aware of these new MRI techniques. We believe that MRI will play a more marked role in the diagnosis and management of incomitant strabismus.

In the last 5 years, we witnessed the progress in the basic and clinical research of strabismus and amblyopia in China, which should be attributed to the effective leadership of the Chinese Ophthalmological Society and the efforts of all members of the professional team. We are glad to see the work of our researchers and clinical scientists in the studies on the molecular and neuronal mechanisms of amblyopia, visual developmental plasticity and functional brain imaging of amblyopia, in the studies on the extraocular muscle's pulley and in the studies on the diagnoses and therapies of strabismus and amblyopia, and furthermore, in epidemiological studies of strabismus and amblyopia. We expect more fruits and creative findings in this field in China in the next decade.

Objective: To investigate the morphological change of extraocular muscle proprioceptor (EMP) in concomitant strabismus and study its pathogenesis., Methods: The samples were obtained from the extraocular muscles of patients with concomitant strabismus and enucleated eyeballs. After being stained, the samples were examined under light microscopy (LM) and transmission electron microscopy (TEM) to count the number of the mitochondria in each sample in an area of 4,000 mm(2) of the axon under the same amplification., Results: Under light microscopy, at the myotendinous junction of the extraocular muscle, the EMP nerve fibers were ended at the initial site or the bilateral sides of a nearby single extrafusal fiber. Under electron microscopy, the general architecture of the receptors in concomitant strabismus was completely disorganized. The nerve component in them had disappeared. The number of the mitochondria in 4,000 mm(2) of the axon in the experimental group was significantly lower than that in the control group (P < 0.05)., Conclusion: The results indicate that in concomitant strabismus, the reception and transmission of proprioceptive information are abnormal, and the morphological EMP disturbance plays an important role in the pathogenesis of concomitant strabismus.

The disc-fovea angle was calculated from the fundus photo by measuring the distance of fovea to the geometric center of the disc and the distance of fovea to the horizontal meridian through the disc center. The authors found the average disc-fovea angle of 40 normal individuals to be extorsion 7.43 degrees; and the diagnosis of cyclotropia was made for patients with extorsion over 14.20 degrees or intorsion, and those in whom the disc-fovea angle difference between both eyes was 8 degrees or over. In 9 cases of AV syndrome, 86% (12/14) of the V pattern cases associated with inferior oblique overaction were excyclotropic, and 75% (3/4) of the A pattern cases were incyclotropic. In 5 cases of superior oblique paresis, 86% (6/7) of the diseased eyes were excyclotropic, whether the function of the antagonistic was normal. The authors concluded that fundus photos could serve as a basis for diagnosis of cyclotropia.