Ribbon Synapses Formed at the Axon of the Calbindin-Immunoreactive ON Cone Bipolar Cell in OFF Sublamina of the Inner Plexiform Layer in the Rabbit Retina / 체질인류학회지

Some retinal neurons, including intrinsically photosensitive retinal ganglion cells have their dendrites stratified in sublamina a of the inner plexiform (IPL), the OFF sublayer, but paradoxically show light-driven ON electrophysiological responses. In order to understand the mechanism on this paradoxical response, by using immunoelectron microscopy with a specific antibody against calbindin, we examined the synaptic connections of the calbindin-immunoreactive ON cone bipolar cell of the rabbit retina, which is thought to make the ribbon synapse in sublamina a of the IPL. The ribbon synapses in sublamina a by calbindin-immunoreactive ON cone bipolar cells were mainly found at the border between the inner nuclear layer and the IPL. Interestingly, the output targets at these ribbon synapses turned out as monads, and multiple synaptic ribbons were engaged in each synapse. These findings were different from those at the conventional ribbon synapse formed by calbindin-immunoreactive ON cone bipolar axon terminals. Thus, these findings may be the characteristics of the calbindin-immunoreactive ON cone bipolar ribbon synapse in sublamina a and can be used to classify the synapse in the retinal circuit research.

A Case of Oculomotor Abnormalities in Congenital Esotropia

Eye alignment is related with binocular connection in the visual cortex during critical period between postnatal 3 and 5 months. Authers examined horizontal pursuit and latent fixation nystagmus using electronystagmogram(ENG)in 6 year old female patient, who was diagnosed a congenital esotropia showing V patten esodeviation, both inferior oblique overaction, dissociated vertical deviation and head turn. In the pursuit examination, symmetric pursuit was observed under binocular viewing. However asymmetric pursuit was observed with smooth pursuit toward temporo-nasal direction and irregular saccade toward naso-temporal direction under monocular viewing. We could observe jerky nystagmus with decelerating velocity under monocular viewig, direction of which was toward fixating eye and degree of which was increased in abduction and decreased in adduction. The direction of pursuit asymmetry and nystagmus were instantaneously reversed when changing occluding eye. The results of ENG were not changed after successful strabismus surgery. We report a typical case of congenital esotropia as one of oculomotor disorders showing asymmetric pursuit and latent fixation nystagmus, which findings were proved by ENG.

The Relationship with the Density of Lens Nucleus and Phacoemulsification Time

To investigate the relationship of the density, thickness of lens nucleus and cortex with phacoemulsification time, we measured the preoperative density and length of lens nucleus and cortex of 100 eyes with a Scheimpflug camera. We performed phacoemulsification on the same phacoemulsification technique using a phacoemulsifier aspirator by the same surgeon. The preoperative mean values of the density of lens nucleus and cortex were 127. 09+/-57.44 and 30. 33+/-15. 24, respectively. The mean values of the thickness for both were 3.05+/-0.42mm and 0.65+/-0.17mm, respectively. The mean value of phacoemulsification time was 92.68+/-56.98 seconds. The phacoemulsification time was increased significantly as the density of lens nucleus was increased (P<0.0001). However, the thickness of the lens nucleus and cortex and the density of cortex had no significant effect on the phacoemulsification time (p=0. 235, p=0.811). Preoperative evaluation with a Scheimpflug camera is particularly valuable for cataractous patients with corneal endothelial disease deciding on phacoemulsification.

Treatment of Total Hyphema Following Trauma and Surgery with Tissue Plasminogen Activator

Delayed clearing from the total hyphema resulting from ocular trauma and surgery causes intractable glaucoma and corneal staining by blood-pigments such as hemoglobin and small amounts of hemosiderin. The management of hyphema includes supportive medical care such as bed rest and surgical procedures such as paracentesis and removal of blood clot to enhance the secretory function of trabecular meshwork. However, surgical intervention has many complications and should be used only when it is absolutely necessary. We used the recombinant intraocular tissue plasminogen activator as a method for minimizing complications and sequeles in three patients with total hyphema. Hyphema resolved in all patients who had been treated with 10ug of recombinant tissue plasminogen activator following 5 days medical treatment. In study, we experienced a case of vitreous hemorrhage. In conclusion, we recommend that eyes with complicated large or total hyphema may be considered for intracameral tissue plasminogen activator as a first procedure comparing to surgical intervention, but further invesigation is needed for timing and dosage of drug usage.

Punctate Inner Choroidopathy

Punctate inner choroidopathy is a clinical disorder of unknown etiology that affects the retinal pigment epithelium and inner choroid resulting in visual loss. Punctate inner choroidopathy is characterized by multiple tiny punctate yellowish-white lesions in the deep retina of posterior pole. There is often an associated serous retinal detachment and subretinal neovascular membrane. The lesions are characterized by small punctate hyperfluorescent in the early phase and leak or stain in the late phase by fluorescein angiography. The authors experienced a case of suspected punctate inner choroidopathy associated with decreased visual acuity in a 24 year-old female and reviewed the available literatures regrading the disease.