Single-cell profiling reveals Müller glia coordinate retinal intercellular communication during light/dark adaptation via thyroid hormone signaling

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.

A Rare Case of Oguchi Disease

Oguchi disease is a rare autosomal recessive disorder and the patients present with congenital stationary night blindnesswith slow dark adaptation. Two causative genes have been reported till date. The fundus shows typical golden sheen patternwhich disappears when they remain in a darkened environment for few hours. We report a case of young girl who presentedwith non-progressive night blindness for 10 years and on examination typical fundus finding of Oguchi disease was revealed.The typical golden sheen fundus disappeared after 3 h of dark adaptation. This case is reported for its rarity as only <50 caseshave been reported till date.

Fundus Albipunctatus Diagnosed in a 9-year-old Female

PURPOSE: We report a case of fundus albipunctatus discovered in a young patient. CASE SUMMARY: A 7.6-year-old female showed numerous small whitish-yellow flecks in the perimacular area and retinal periphery. Dark adapted 0.01 electroretinography (ERG) and dark adapted 3.0 ERG were profoundly reduced. At 26 months after the first visit, the best-corrected visual acuities were 1.0 right eye and 0.9 left eye. There were no pigmented lesions, atrophic lesions, or vascular abnormalities in the retina. Humphrey and Goldmann visual field tests were performed, but neither of the tests revealed any scotomas or other visual field defect. The number and size of characteristic numerous small whitish-yellow retinal flecks seemed almost unchanged. In spectral domain-optical coherence tomography (SD-OCT), the subretinal hyper-reflective lesions spanned the retinal pigment epithelium and the external limiting membrane. ERG showed improved dark adapted responses (dark adapted 0.01 ERG and dark adapted 3.0 ERG) after prolonged dark adaptation (2.5 hours). No family member showed any abnormal findings. CONCLUSIONS: Fundus albipunctatus is a rare disease in Koreans. We report a case diagnosed using fundus photography, SD-OCT, visual field tests, and ERG after prolonged dark adaptation (2.5 hours).

Specific Spectral Domain Optical Coherence Tomographic Findings of Oguchi Disease

PURPOSE: To report specific spectral domain OCT findings of Oguchi disease diagnosed with fundoscopic examination and electrophysiological study. CASE SUMMARY: A 14-year-old patient visited our clinic with a complaint of night blindness for ten years. Fundoscopic examination showed a golden-yellow fundus reflex. After three hours of dark adaptation, the fundus color returned to normal (Mizuo-Nakamura phenomenon). In full-field ERG, rod b-wave was not detectable. The a-wave amplitude in maximal combined response increased after three hours of dark adaptation, although the b-wave amplitude was similar to the amplitude before dark adaptation, demonstrating a negative waveform. In the spectral domain OCT images of the perifoveal area, no gap between the retinal pigment epithelium and the inner segment/outer segment (IS/OS) junction was detected before prolonged dark adaptation, and a highly reflective band was shown. However, the gap appeared after three hours of dark adaptation, and two highly reflective bands were detected in the OCT images. CONCLUSIONS: The characteristic OCT finding in addition to the specific fundoscopic finding and full-field ERG results may be useful to diagnose Oguchi disease.

The determination of dark adaptation time using electroretinography in conscious Miniature Schnauzer dogs

The optimal dark adaptation time of electroretinograms (ERG's) performed on conscious dogs were determined using a commercially available ERG unit with a contact lens electrode and a built-in light source (LED-electrode). The ERG recordings were performed on nine healthy Miniature Schnauzer dogs. The bilateral ERG's at seven different dark adaptation times at an intensity of 2.5 cd.s/m2 was performed. Signal averaging (4 flashes of light stimuli) was adopted to reduce electrophysiologic noise. As the dark adaptation time increased, a significant increase in the mean a-wave amplitudes was observed in comparison to base-line levels up to 10 min (p > 0.05). Thereafter, no significant differences in amplitude occured over the dark adaptation time. Moreover, at this time the mean amplitude was 60.30 +/- 18.47 microV. However, no significant changes were observed for the implicit times of the a-wave. The implicit times and amplitude of the b-wave increased significantly up to 20 min of dark adaptation (p > 0.05). Beyond this time, the mean b-wave amplitudes was 132.92 +/- 17.79 microV. The results of the present study demonstrate that, the optimal dark adaptation time when performing ERG's, should be at least 20 min in conscious Miniature Schnauzer dogs.

Relative Afferent Pupillary Defect and Electroretinogram in Patients with Asymmetric Cataracts

PURPOSE: To investigate the incidence, associated factors, and the prognostic significance of relative afferent papillary defect (RAPD) in the eyes with less severe cataract and determine which mechanism of 'scattering' or 'dark adaptation' is more applicable, we evaluated 40 patients with asymmetric cataract (AC). METHODS: Forty patients of AC with the differences of three lines or more of visual acuity by Han's visual acuity chart underwent ophthalmic examinations including the 'swinging flashlight test' and electroretinogram before and after cataract surgery. RESULTS: There were nineteen patients who showed definite RAPD in the eyes with less severe cataract. The differences of log MAR between the two eyes were more than 1.55 or less than 0.73 in 17 patients (89.5%) with RAPD. Degree of posterior subcapsular opacity was marginally associated with RAPD in the eyes with less than 1.06 of log MAR differences. There was no association between the presence of RAPD and postoperative visual acuities. In the eyes with RAPD, b wave amplitudes tended to be smaller in the eyes with more severe cataract than those with less severe cataract before dark adaptation. However, after dark adaptation, b wave amplitudes tended to be larger in eyes with more severe cataract than those in the eyes with less severe cataract, and preoperatively than postoperatively. CONCLUSIONS: The incidence of RAPD of less severe cataract eye was significant (48%) but RAPD was not associated with visual acuity prognosis. The results of electroretinogram more favored 'scattering ' than 'dark adaptation' as the mechanism of RAPD phenomenon.

The Changes of ERG b-wave and Oscillatory Potentials in White Rats according to Dark Adaptation and Stimulus Light Intensity

Authors studied changes of ERG b-wave and oscillatory potentials(OPs) in white rats according to dark adaptation and stimulus light intensity for experimental setting. For this purpose we performed ERG tests on 10 normal white rats(20 eyes) during progressive dark adaptation. ERG b-wave and OPs values increased significantly during the first 30 minutes and then made plateau pattern. Based on this result we concluded that 30 minutes dark adaptation was sufficient for getting stable rat ERGs. After 30 minutes of dark adaptation, ERG b-wave and OPs were measured in response to 0.3J(2.25 cd.s/m2), 0.6J(6.5 cd.s/m2) , 2J(27.5 cd.s/m2) light intensity. In ERG b-wave there was no significant differene between 0.3J and 2J. In OPs between 0.3J and 0.6J, the sum of amplitude was significantly increased(p0.05). We concluded that 0.3J(2.25 cd.s/m2) was sufficient in ERG testing. And in OPs at least 0.6J(6.5 cd.s/m2) was needed for proper stimulation.

The Chantres of ERG b-wave and Oscillatory Potential in White Rat during Dark Adaptation

We studied changes of b-wave and oscillatory potential in ERG test during dark adaptation in white rats for the purpose of using it in experimental disease-group and studying difference in man. For this we performed ERG test on normal 14 S-D (Sprague-Dawley) rats (28 eyes) during dark adaptation. The implicit time of a-wave and b-wave was shortend during dark adaptation. The b-wave and oscillatory potential rapidly increased by 20 and 30 minutes during dark adaptation: in b-wave, these values were 425.89 +/- 141.15 micro v, 473.65 +/- 130.35 micro v respectively, and in oscillatory potential, 110.56 +/- 54.82 micro v, 126.27 +/- 48.24 micro v respectively. After then, these were slightly increased. This results reveal that dark adaptatin in ERG test using rats needs sufficient time from 20 minutes to 30 minutes in similar to man. The oscillatory potential in white rat had three components with 1] light stimulus and the increase of amplitude of oscillatory potential was similar to that of b-wave during dark adaptation. But we should consider that the decreased cone function of white rat was different from that of man, that amplitude of b-wave was continously increased without the break point of early 6 minutes, and that the implicit time of b-wave was continously decreased after 10 minute during dark adaptation, when we use rat.

Dark Adaptation of Diabetic Retinopathy / 第二军医大学学报

37 diabetic patients and 49 normal subjects were examined with Goldmann-Weekers dark adaptometer.The results showed that the absolute thresholds of dark adaptation in each group of diabetic patients were higher than those in normal controls. The more severe retinopathy was, the higher was the absolute threshold.The patients with more damaged visual acuity showed worse dark adaptation. However the dark adaptation in patients with good visual acuity was also abnormal.lt is suggested that dark adaptation is more sensitive than visual acuity in determining the visual function of diabetic patients.

STUDY OF MICRONUTRIENT COMPOUNDS ON IMPROVEMENT OF DARK ADAPTATION FUNCTION / 营养学报

The effect of micronutrient complex preparations on dark adaptation function was studied in human body. Sixty-four young students, 18 to 20 years of age, were divided into four groups. Under the normal dietary condition, the experimental groups were supplemented with different microcutrient complex preparations for two weeks.Before and after the experiment serum vita- min A and zinc level, quick dark adaptation time, near-sighted in dim light time and absolute threshold were determined. It was found that dark adaptation was much improved in the group supplemented with adequate vitamin A as well as other vitamins and zinc. So we suggested that micronutrient complex preparation should be given to operators who will concentrate their sight in low illuminance for maintaining their visual function.