PURPOSE: To identify a subtype of cone photoreceptor in the mammalian retina using enzyme histochemical method. METHODS: In human, rabbits and cats, identification of cone photoreceptor was tried with carbonic anhydrase after retinal tissue isolation and section. RESULTS: In human, subtype of cone photoreceptor was identified. In rabbits, one type of carbonic anhydrase negative regular cell was detected and suspected as rod cells. In cats, only blue cone cell and rod cell were detected and no red-green cone cell was detected. CONCLUSIONS: In cats and rabbits, identification of red-green cone cell and blue cone cell was difficult. So, enzyme histochemical identification of cone photoreceptor using carbonic anhydrase need more research to imply in mammalian retina.
Animals ; Carbonic Anhydrases ; Cats ; Humans ; Rabbits ; Retina* ; Retinal Cone Photoreceptor Cells* ; Retinaldehyde

In order to study the functional and structural alterations of the retina in SD rat model after methanol intoxication, 35 rats were divided randomly into five groups administrated with saline, 3-day high dose, 7-day high dose, 3-day low dose and 7-day low dose methanol separately. The retinal function of each group was assessed by flash electroretinogram (F-ERG) 3 and 7 days after methanol poisoning. The microstructure and ultrastructure of the retina were observed at the same time. The high-dose methanol intoxication induced irreversible retinal functional and structural damages 3 days after poisoning, which included prolonged latency and reduced amplitude of the Max-reaction of F-ERG. These injuries were aggravated 7 days after poisoning. Meanwhile, the latency and amplitude of the Cone-reaction of F-ERG were also affected 3 days after poisoning, but there were no further worsening tendency 7 days after poisoning. The retinal histological analysis showed cellular edema, heteromorphy and disarrangement, tissular loosen of the inner nuclear layer and photoreceptors layer. The mitochondrial damage began at the photoreceptors layer and developed further into the inner nuclear layer. The low-dose methanol intoxication only caused transient damage of the retina. Our results showed that the function and structure of the photoreceptor and inner nuclear layer were the primary target of methanol intoxication and that the rod cells were more sensitive to methanol intoxication than the cone cells. The mitochondrial damage developed from outer layer to inner layer of the retina.
Animals ; Edema/pathology* ; Electroretinography ; Forensic Medicine ; Male ; Methanol/poisoning* ; Mitochondria/pathology* ; Photoreceptor Cells/pathology* ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Retina/physiopathology* ; Retinal Cone Photoreceptor Cells/pathology* ; Retinal Diseases/pathology* ; Retinal Rod Photoreceptor Cells/pathology* ; Time Factors

OBJECTIVE: To determine the relationship between hypothyroidism and color vision deficiency among Filipinos ages 20-60 years
DESIGN AND METHODS: A cross-sectional study was performed on 91 biochemically hypothyroid and euthyroid patients seen at the Makati Medical Center from July to December 2013. All subjects underwent the Ishihara color test, followed by the Farnsworth-Munsell D15 test if this was positive. The patient who tested positive in the Farnsworth-Munsell D15 test was referred to an ophthalmologist to rule out any anatomic problem, and was excluded from the study if found to have any. Fisher's exact test assessed the significant correlation between hypothyroidism and color vision deficiency. A p-value less than 0.05 was considered significant.
RESULTS: Of the 91 patients that were included in the study, the average age was 42 years, majority (87%) were females, and 41% were biochemically hypothyroid. All euthyroid patients (100%) had normal color vision, while one hypothyroid patient (3.0%) tested positive for color vision deficiency (p-value 0.407).
CONCLUSION: Based on this study, the hypothyroid state of the patients had no effect on their color vision, unlike those seen in rodents, probably because mature human cones are not as easily affected by changes in thyroid hormone levels.

Human ; Male ; Female ; Middle Aged ; Adult ; Color Vision Defects ; Color Vision ; Ophthalmologists ; Retinal Cone Photoreceptor Cells ; Thyroid Hormones ; Hypothyroidism

Light adaptation enables the vertebrate visual system to operate over a wide range of ambient illumination. Regulation of phototransduction in photoreceptors is considered a major mechanism underlying light adaptation. However, various types of neurons and glial cells exist in the retina, and whether and how all retinal cells interact to adapt to light/dark conditions at the cellular and molecular levels requires systematic investigation. Therefore, we utilized single-cell RNA sequencing to dissect retinal cell-type-specific transcriptomes during light/dark adaptation in mice. The results demonstrated that, in addition to photoreceptors, other retinal cell types also showed dynamic molecular changes and specifically enriched signaling pathways under light/dark adaptation. Importantly, Müller glial cells (MGs) were identified as hub cells for intercellular interactions, displaying complex cell‒cell communication with other retinal cells. Furthermore, light increased the transcription of the deiodinase Dio2 in MGs, which converted thyroxine (T4) to active triiodothyronine (T3). Subsequently, light increased T3 levels and regulated mitochondrial respiration in retinal cells in response to light conditions. As cones specifically express the thyroid hormone receptor Thrb, they responded to the increase in T3 by adjusting light responsiveness. Loss of the expression of Dio2 specifically in MGs decreased the light responsive ability of cones. These results suggest that retinal cells display global transcriptional changes under light/dark adaptation and that MGs coordinate intercellular communication during light/dark adaptation via thyroid hormone signaling.
Animals ; Mice ; Dark Adaptation ; Light ; Retina ; Retinal Cone Photoreceptor Cells/metabolism* ; Adaptation, Ocular ; Neuroglia/physiology* ; Cell Communication ; Thyroid Hormones

OBJECTIVETo study the effect of Vaccinium uliginosum L., (VU) on the electroretinogram (ERG) and retinal pathological changes in rabbits after light-induced damage.

METHODSTwenty-eight Chinchilla rabbits were randomly divided into four groups: administration beforehand (A), administration after injury (B), light injury without administration (C), and blank (D) groups. After a 4-week administration of VU homogenate at 4.8 g/(kg·d) once a day in group A, ERG in groups A, B and C were recorded according to the standards set by the International Society for Clinical Electrophysiology of Vision (ISCEV). Except for group D, the groups were then exposed to strong light. Just after that, group A stopped receiving VU treatment and group B started to receive it. Then ERGs in all groups were recorded after 1 day, 1 week, and 2 weeks. Throughout the whole process groups which were not fed with VU were fed with normal saline. Finally, the tissues and structures of all the groups were observed and the thickness of the outer nuclear layers (ONL) was measured.

RESULTS(1) After 4-week feeding with VU, the latency time of ERG in group A became shorter than those in the other groups and the amplitude increased. After being exposed to strong light, the latency time lengthened and amplitude decreased in all the injury groups, but comparing at each time point, the measured values in group A were better than those in group C. With the accumulation of VU, the ERG in group B improved, and finally, all of the detected values became better than those in group C. (2) Retinae in group D were normal in histology and the layers were in order but those in group C became disarranged. The injuries in groups A and B were minor compared with those in group C. The thickness of the ONL in group C was significantly thinner than in the other groups (P=0.000), and that in groups A and B was thicker than that in group C, although thinner than in group D. That in group A was thicker than in group B.

CONCLUSIONSVU can relieve the injury to rabbit retinae exposed to normal day and night rhythm, alleviate the harm caused by light when used beforehand, and repair the light damage to the retina.

Animals ; Electroretinography ; Light ; Plant Extracts ; pharmacology ; Rabbits ; Retina ; drug effects ; pathology ; physiopathology ; radiation effects ; Retinal Cone Photoreceptor Cells ; drug effects ; pathology ; radiation effects ; Retinal Rod Photoreceptor Cells ; drug effects ; pathology ; radiation effects ; Time Factors ; Vaccinium ; chemistry

The cone cell on the retina of human is the sensor of vision under illumination; it can be classified into three types: red cone cell, green cone cell, and blue cone cell. There is different property of absorbing light for each type of cone cell. In this work, a 10 Hz pulse was used to drive red, green and blue light emitting diodes respectively, and the different monochromatic light with the same luminance was obtained. The eyes of ten subjects were stimulated by different monochromatic light independently; an EGI system with 128 channels was used to record the steady-state visually evoked potential (SSVEP). After applying the fast fourier transform (FFT) to the SSVEP data, we found that the distribution of the neural network in the initial vision cortex activated by the output of the different-typed cone cell remained mainly identical, but there was some difference in intensity between the three types of network: the activity by blue light is the strongest one, that by red light is in the middle, and that by green light is the weakest one.
Brain ; physiology ; Color ; Color Perception ; physiology ; Electroencephalography ; methods ; Evoked Potentials, Visual ; physiology ; Female ; Humans ; Light ; Male ; Photic Stimulation ; Retinal Cone Photoreceptor Cells ; physiology ; Young Adult

PURPOSE: To investigate the morphologic changes in the outer retina of patients with cone dystrophy, using spectral-domain optical coherence tomography (SD-OCT). METHODS: The medical records of 15 cone dystrophy patients examined from January 2007 to January 2012 were reviewed retrospectively. All patients underwent ophthalmic evaluation including best-corrected visual acuity (BCVA), color vision testing, fundus examination, full-field standard electroretinography (ERG), multifocal (mf) ERG, and SD-OCT. Qualitative and quantitative SD-OCT data and ERG responses were analyzed and compared among the patient categories and the normal control group. RESULTS: There were 4 major categories of SD-OCT findings, based on the status of the ellipsoid portion of the photoreceptor inner segment (ISe), outer segment (OS) contact cylinder, and retinal pigment epithelium (RPE) layer. Category 0 showed no structural abnormalities. Category 1 showed foveal ISe loss and obscurity of the border between the ISe band and the external limiting membrane (ELM). Category 2 showed foveal thinning and focal foveal ISe disruption with an intact ELM. Category 3 showed foveal thickening and perifoveal disruption of the ISe layer. Category 1 to 3 showed OS contact cylinder layer absence and RPE thickening. The patients in category 0 tended to be younger (mean, 10.0 years) than those in categories 1 to 3 (mean, 17.6 years), although this difference was not statistically significant. Category 1 to 3 patients exhibited statistically significant thinning of the central retina and outer nuclear layer and thickening of the RPE layer relative to the category 0 and normal control group. There was a significant correlation between the central foveal thickness and BCVA in the patients with cone dystrophy. ERG and mfERG responses did not differ significantly among the different cone dystrophy categories. CONCLUSIONS: The morphologic features of cone dystrophy as revealed by SD-OCT, could be categorized as either normal or 1 of 3 different types of outer retinal changes. The presence of normal retinal structures in young cone dystrophy patients with functional impairment (category 0) indicates that electrophysiologic studies are superior to current imaging modalities for the early diagnosis of cone dystrophy. The characteristic SD-OCT findings in cone dystrophy patients may aid in differential diagnosis and be useful for future research on the pathology of cone dystrophy.
Adolescent ; Adult ; Child ; Child, Preschool ; Electroretinography ; Female ; Fluorescein Angiography ; Fundus Oculi ; Humans ; Male ; Middle Aged ; Ophthalmoscopy ; Reproducibility of Results ; Retinal Cone Photoreceptor Cells/*pathology ; Retinal Dystrophies/*pathology/physiopathology ; Retrospective Studies ; Tomography, Optical Coherence/*methods ; Visual Acuity ; Young Adult

It was previously found that the efficacy of synaptic transmission between retinal cone systems and luminosity-type horizontal cells (LHCs) was activity-dependent. Repetitive activation of red-cone pathway increased the LHCos hyperpolarizing response to red light, and the response enhancement was reversible. In this study, intracellular recording and pharmacological method were applied to investigate the mechanism(s) underlying red-flickering-induced response enhancement. Lowering intracellular Ca(2+) in the LHC by intracellular injection of Ca(2+) chelator EGTA prevented the development of red-flickering-induced response enhancement, which implicates the importance of postsynaptic calcium signal. The response enhancement could also be eliminated by a potent antagonist of Ca(2+)-permeable AMPA receptor (CP-AMPAR), which suggests the possibility that Ca(2+) influx via glutamate-gated calcium channels is related to the changes of [Ca(2+)](i). Furthermore, the administration of ryanodine or caffeine also attenuated the phenomenon, which gives evidence that the local calcium signal caused by intracellular calcium-induced calcium release (CICR) may be involved. Taken together, our data implicate that postsynaptic CICR and CP-AMPAR are related to the activity-dependent response enhancement.
Animals ; Caffeine ; pharmacology ; Calcium ; metabolism ; Carps ; Neuronal Plasticity ; physiology ; Receptors, AMPA ; physiology ; Retina ; cytology ; Retinal Cone Photoreceptor Cells ; physiology ; Ryanodine ; pharmacology ; Ryanodine Receptor Calcium Release Channel ; physiology ; Signal Transduction ; physiology ; Synapses ; physiology