Analysis of retinal sublayer thickness in Leber hereditary optic neuropathy and G11778A mutation carriers / 中华眼底病杂志

Objective:To analyze the thickness of peripapillary retinal nerve fiber layer (pRNFL) and photoreceptor (PR) sublayer in Leber hereditary optic neuropathy (LHON) and G11778A mutation carriers. Methods:A cross sectional study. From September 2020 to October 2021, 68 LHON patients (136 eyes) (patient group) and 40 G11778A mutation carriers (80 eyes) of LHON patients' families (carrier group) were included in the study. All patients were found to have G11778A mutation by Genetic testing. Forty healthy volunteers with 80 eyes matched to the age and gender of the patient group were recruited as a normal control group. All eyes were examined by optical coherence tomography (OCT). The pRNFL thickness was automatically measured by the built-in software of the OCT device. The total retinal thickness (MT) and the thickness of the outer bundle layer (OPL), outer nuclear layer (ONL), external limiting membrane to retinal pigment epithelium (ELM-RPE) in macular OCT images were measured by Image J software. Linear mixed model was used to analyze and compare the thickness of pRNFL, macular fovea and four layers above the nasal and temporal paracentral retina in patients, carriers and normal controls. The correlation between pRNFL and macular retinal sublayer thickness and the course of disease was also analyzed. Results:The thickness of the upper and lower pRNFL, temporal pRNFL and average pRNFL of the patients were smaller than those of the carriers and the normal control group ( P<0.01), and the nasal pRNFL thickness of the patients was smaller than that of the carriers ( P<0.01). Fovea: compared with the normal control group, the thickness of MT and ONT in the patient group was decreased, ONL thickness decreased in carrier group, with the significant different ( P<0.05). Parafovea: compared with normal control group, the thickness of MT and temporal ONL decreased and temporal OPL increased in the patients group, with the significant different ( P<0.05). In the carrier group, the thickness of MT and temporal, nasal ONL decreased, and the thickness of nasal OPL increased, with the significant different ( P<0.05). Compared with the carrier group, the MT thickness of the patient group was decreased, and the nasal ONL and nasal ELM-RPE thickness were increased, with the significant different ( P<0.05). Correlation analysis results showed that the thinning of pRNFL in the superior, nasal, temporal and average ( r=-0.22, -0.21, -0.25, -0.22), and the thickening of ELM-RPE in foveo-temporal ( r=0.19) were correlated with the course of disease ( P<0.05). Conclusions:The pRNFL of LHON patients with G11778A mutation becomes thinner and is related to the course of the disease. There were significant differences in the thickness of MT and PR sublayers between patients and carriers compared to the normal control group.

Vitreomacular traction release: Finding the edge

Background: Vitreomacular traction (VMT) is a commonly encountered entity in our routine practice. The key question is whether to observe or operate by clinical and imaging based judgement of the visual prognosis in every case. Purpose: This video encapsulates diagnostics, surgical method, and prognosis in a case of VMT released with vitrectomy. Synopsis: A 56-year-old businessman was diagnosed with VMT in the OPD and was advised surgical release of the same. The patient was extremely keen to know the visual prognosis, where the OCT imaging helped. The surgical method demonstrates the method to find the edge of the PVD to release the traction. Also, a simple ILM peel procedure has been described to reduce recurrences in cases like these. Highlights: 1. Judging the prognosis in VMT cases on basis of imaging. 2.Finding the edge (FTE) method of inducing the PVD. 3. ILM peeling simplified

Anti-retinal antibodies and their role in autoimmune retinopathy / 中华实验眼科杂志

Autoimmune retinopathy (AIR) is a group of immune-mediated retinopathies that usually results in severe loss of vision and visual field defects.AIR mainly includes paraneoplastic and non-paraneoplastic syndromes.One main feature of AIR is the presence of circulating anti-retinal antibodies (ARAs) in peripheral blood, which are produced through anti-tumor responses, anti-microbial responses, and immune responses induced by autoantigen fragments following retinal injury, and mainly attack retinal photoreceptor cells.ARAs are important for the diagnosis, progression assessment and treatment outcome of AIR.These ARAs often appear before the diagnosis of cancer and can be helpful for the early detection of malignant tumors.The mechanism of ARAs production, its pathological role in AIR, and its significance in clinical practice were reviewed in this article.

Progress of retinal organoids in treatment of retinal degenerative diseases / 国际眼科杂志(Guoji Yanke Zazhi)

@#Retinal degeneration is the primary cause of visual impairment and blindness. However, in advanced stage of the disease, the majority or all photoreceptors are lost, effective therapeutics has not been established. In recent years, a large number of studies have provided new ways for the replacement of photoreceptors and three-dimensional retinal culture has emerged to produce retinal photoreceptors and tissues of both fetal mouse and human, providing the cell source of photoreceptors replacement therapy for treating retinal degenerative diseases. This review focuses on the development of three-dimensional retinal culture techniques and photoreceptors transplantation experiments, and the existing application strategies and limitations of retinal organoids in the replacement therapy of retinal degeneration, which provide a theoretical reference for the optimization of 3D retina in photoreceptors replacement therapy.

The relationship between the sizes of idiopathic macular hole and the healing types of fovea photoreceptor layer after vitrectomy / 中华眼底病杂志

Objective To observe the relationship between the size of idiopathic macular hole (IMH) and the healing types of postoperative photoreceptor layer after vitrectomy.Methods This prospective uncontrolled study included 33 eyes of 31 consecutive patients who underwent vitrectomy for IMH.There were 9 males (9 eyes) and 22 females (22 eyes),with the mean age of (58.16± 9.10) years.The mean duration of symptoms was (4.97± 5.97) months.The best corrected visual acuity (BCVA) and optical coherence tomography (OCT) were measured for all patients.BCVA was measured with international standard visual acuity chart and then converted to logarithm of the minimum angle of resolution (logMAR).The mean logMAR BCVA was 1.07± 0.38.The mean intraocular pressure was (14.05±0.54) mmHg (1 mmHg=0.133 kPa).The minimum size of the macular hole (MIN),the base diameter of the macular hole (BASE),the average width of the macular hole (AWMH) and the average height of the macular hole (AHMH) were (465.19± 232.84),(943.63 ± 389.26),(704.72 ± 292.64),(443.84± 72.47) μm,respectively.According to the MIN value,the hole size were divided into small,medium and large group which had 9 eyes,15 eyes,9 eyes,respectively.According to the postoperative OCT characteristics,the healing types of the photoreceptor layer were divided into 0-Ⅳ types.All patients underwent pars plana vitrectomy (25G or 27G standard three-incision) with internal limiting membrane peeling with tamponade agents.The mean follow-up was (326.42 ± 157.17) days.The first postoperative OCT characteristics were defined as the early period.The therapy results were evaluated according to the last follow-up time point.BCVA and intraocular pressure before and after operation were compared by paired t test.The postoperative BCVA were compared with preoperative BCVA,MIN,AWMH,AHMH and follow-up using Pearson correlation analysis.Results At the last follow-up,the LogMAR BCVA was 1.52-1.40 in 3 eyes,1.30-0.52 in 22 eyes and 0.40--0.07 in 8 eyes.Compared with preoperative that,the difference was statistically significant (t=-6.023,P＜0.001).The photoreceptor healing was type 0 in 10 eyes (30.3％),type Ⅰ in 4 eyes (12.1％),type Ⅱ in 10 eyes (30.3％),type Ⅲ in 9 eyes (27.3％) at the early postoperative period.The photoreceptor healing was type 0 in 5 eyes (15.2％),type Ⅰ in 5 eyes (15.2％),type Ⅲ in 12 eyes (36.4 ％),type Ⅳ in 11 eyes (33.3％) at the last follow-up.The preoperative size ofIMH was negatively correlated to the photoreceptor healing types at early postoperative period (r=-0.590,P＜0.01) and the last follow-up (r=-0.768,P＜0.01),respectively.The correlation analysis showed that the postoperative BCVA associated with the preoperative BCVA,the stage of the macular hole,the size of the macular hole,MIN,BASE,AWMH,AHMH,the healing types ofphotoreceptor layer of the early and the last follow-up after surgery (r=0.500,0.370,0.470,0.435,0.533、0.505,0.462,-0.442,-0.656,P＜0.05).There was no correlation between age,visual decreasing times and follow-up times (r=0.285,0.234,-0.310,P＞0.05).Conclusion The preoperative sizes of IMH were associated with the postoperative healing types of photoreceptor layer.

Induce and differentiation of pig Müller cells into photoreceptors in vitro / 中华实验眼科杂志

Background Recent studies indicated that rat and mouse Müller cells can be induced and differentiated into photoreceptor-like cells in vitro, but it is not known whether this also happens to adult pig Müller cells nowadays.Objective This study was to test whether adult pig Müller cells can be differentiated to the retinal photoreceptors (the primary transmission neurons of the retina) in vitro.Methods Müller cells were isolated from the neural retina of adult pig eyes and cultured and passaged.The 3rd and 4th generation of cells were themonolayerly cultured,and the cells forced to form spheres in suspension in altra-low adherent dishes for 2-3 days first and then reseeded in normal adherent plates,and both of them were cultured in a specifically formulated medium to induce the differentiation of retinal photoreceptor.The cells was verified by immunocytochemistry.Cell morphology and immunofluorescence staining were utilized to measure the efficacy of the differentiation.Results The 2nd,3rd and 4th generation of Müller cells expressed glutamate synthetase (GS) , a specific maker of Müller cells.Inaddition, the 3rd generation of cells also expressed glial fibrillary acidic protein (GFAP) and another specific maker of Müller cells.Three visual fields under fluorescence-microscope were randomly chosen to calculate the average positive ratio of rhodopsin,a specific marker of mature photoreceptors.The photoreceptor differentiation ratios of the 2nd generation of cells for monolayer culture only and with additional sphere suspension culture were (27.99±6.53 (％ and (16.54±3.40) ％ , respectively.With passages, the number of rhodopsin positive cells gradually decreased, and the intensity of rhodopsin expression gradually weakened.The directed rhodopsin positive ratios of the 2nd,3rd and 4th generation of cells from sphere formation were (56.23±7.32)％ , (36.26 ±8.55)％ and (12.68 ±3.18)％ , respectively.Although the rhodopsin expression was weakened over passages,the differentiated cells were more slender and elongated.There was no statistic ally significant difference between different groups (F =2.618, P =0.099).Conclusions Adult pig Müller cells can be differentiated into retinal photoreceptors in vitro.The morphology of the differentiated cells appears moreslender and elongates if the sphere-induced differentiation method is used and/or the directed differentiation time is further extended.

Interrelationships between the Retinal Neuroglia and Vasculature in Diabetes

For years, diabetic retinopathy has been defined based on vascular lesions, and neural abnormalities were not regarded as important. This review summarizes evidence that the neural retina has important effects on the retinal vasculature under normal conditions, and the interaction between the retinal neuroglial cells and vascular function is altered in diabetes. Importantly, new evidence raises a possibility that abnormalities within retinal neuroglial cells (notably photoreceptors) might actually be causing or initiating the vascular disease in diabetic retinopathy.

Optogenética e estimulação óptica neural: estado atual e perspectivas / Optogenetics and neural optical stimulation: current state and perspectives

Ao longo dos últimos 50 anos, o uso da luz, em especial o laser, vem promovendo grandes avanços em diversas áreas da ciência e da tecnologia. Na última década o uso de estímulos ópticos no campo da biomédica tem despertado grande interesse no meio acadêmico e na indústria. Dois ramos que se destacam pelo seu crescimento são: a estimulação óptica direta e a optogenética. A primeira utiliza diferentes parâmetros da luz para adequar o efeito desejado na interação com o tecido biológico. A segunda faz uso de engenharia genética para tornar os tecidos biológicos sensíveis à luz. A estimulação neural por infravermelho (estimulação óptica direta) não necessita de contato direto com o tecido e apresenta maior seletividade especial se comparada à estimulação elétrica, mas tem a capacidade restrita de ativar (despolarizar) os neurônios. A optogenética, entretanto, pode ser utilizada para manipular o tecido neural tornando-o sensível à luz; sendo, então, possível despolarizar ou hiperpolarizar os neurônios codificados, assim como monitorar as ativações por meio de codificação de proteínas fluorescentes sensíveis à tensão elétrica. Tanto a técnica de estimulação óptica por infravermelho ou a técnica de optogenética, vêm sendo aplicadas apenas à modelos animais. Os resultados mostram, entretanto, que há grande viabilidade de aplicação da estimulação óptica em seres humanos. Futuramente, tais técnicas poderão substituir o atual padrão ouro para a ativação neural, a estimulação elétrica, em aplicações envolvendo doenças neurológicas específicas.

Within the last 50 years the light and specially the laser has fomented great advances in several areas of science and technology. During the past decade the use of optical stimuli in the biomedical research field have been of great interest for both academy and industry. Two research branches that can be highlighted due to its growth are: direct optical stimulation and optogenetic. The first one uses different parameters of light to optimize the desired effect on the tissue interaction. The other branch works with genetic engineering technics to make cells sensitive to light. The neural stimulation by infrared (direct optical stimulation) does not require direct contact with the tissue and has higher spatial selectivity when compared to electrical stimulation, but it has restricted ability to activate (depolarize) neurons. The optogenetic, however, can be used to manipulate the neural tissue depolarizing or hyperpolarizing encoded neurons, as well as monitor activations by encoding fluorescent proteins sensitive to voltage. The stimulation by infrared optical or optogenetic, has been applied only to animal models although there is a great possibility for human applications. In the future, it may even replace existing techniques such as electrical brain stimulation to treat specific neurological diseases.

Trasplante de tejido retiniano y de células progenitoras retinianas: una promesa terapéutica para pacientes con enfermedad de la retina / Retinal tissue transplantation and retinal progenitor cells: a therapeutic promise for patients with retinal disease

La retinopatía diabética, la degeneración macular relacionada con la edad y la retinitis pigmentosason las enfermedades retinianas más frecuentes en todo el mundo. A pesar de no contar consuficientes estudios que demuestren resultados funcionales positivos en cuanto a recuperar lafunción visual, el uso de células madre y células progenitoras retinianas y el trasplante de retinafetal parecen bastante promisorios. Hasta el momento no se han podido obtener resultadospositivos sobre la funcionalidad de las células trasplantadas, pero sí se ha demostrado que elprocedimiento para transferir el tejido retiniano es seguro y confiable. Aún no se ha intentadoen seres humanos el trasplante de células progenitoras retinianas, pero dicho trasplante ha dadoresultados satisfactorios en modelos múridos. Los estudios con células progenitoras retinianashan logrado demostrar en modelos múridos que se activan y expresan los fotorreceptores. Existenalgunas barreras de disponibilidad para el uso de células progenitoras retinianas, que se debensuperar con el fin de adelantar estudios que permitan aumentar las posibilidades de integracióny diferenciación de dichas células hacia fotorreceptores.

Retinal tissue transplantation and retinal progenitor cells: A therapeutic promise for patients with retinal diseaseWorldwide, diabetic retinopathy, age-related macular degeneration, and retinitis pigmentosahave the highest incidence rate among retinal diseases. Despite the lack of enough trialsdemonstrating positive functional results on eyesight recovery, the use of stem cells, retinalprogenitor cells, and fetal retinal tissue transplantation seem very promising. So far positiveresults on the functionality of the transplanted cells have not been obtained. However, the safetyand reliability of the procedure to transfer retinal tissue have been demonstrated. Transplantationof retinal progenitor cells has not been tried on human beings, but there have been satisfactory results with it in murine models. Trials with retinalprogenitor cells have demonstrated activation andexpression of photoreceptors in murine models. Somebarriers of availability exist for the use of retinalprogenitor cells that must be overcome in order tocarry out studies to increase the possibility of theirintegration and differentiation towards photoreceptors.

Estudo experimental da aplicação retiniana do laser infravermelho via transescleral sob condições de baixa visibilidade / Transscleral infrared laser retinal photocoagulation experimental study under low visibility conditions

OBJETIVOS: Pesquisa experimental, com laser de diodo infravermelho, para estimar a segurança, a reprodutibilidade e a permeabilidade da parede ocular à sua atuação clínica, quando aplicado via transescleral, em condições de baixa visibilidade. MÉTODOS: Submetemos olhos de coelhos pigmentados da raça Nova Zelândia à fotocoagulação retiniana por laser de diodo infravermelho. No olho direito, realizamos fotocoagulação via transescleral sob parâmetros de potência e tempo pré-determinados clinicamente. No olho esquerdo, foram repetidos os mesmos valores da potência e tempo usados no olho direito, desta vez, via transpupilar. Imediatamente e após 2 meses, estudos clínicos baseados na retinografia e histopatológicos foram realizados. RESULTADOS: A permeabilidade da parede ocular, quando da aplicação do laser de diodo infravermelho via transescleral, variou entre 58,95 e 63,87 por cento. A média da permeabilidade da parede ocular a 300 mW (63,14 por cento) mostrou-se significativamente superior àquela da permeabilidade da parede ocular encontrada a 500 mW (59,11 por cento), (P<0,05). CONCLUSÕES: Este estudo sugere a existência da relação dose-resposta em relação aos parâmetros empregados na aplicação do laser de diodo infravermelho via transescleral, com permeabilidade da parede ocular mensurável e reprodutível. Nenhuma rotura, hemorragia ou descolamento da retina ou vítreo foi constatado aos exames subseqüentes às aplicações do laser de diodo infravermelho, o que torna o uso da fotocoagulação via transescleral, no modelo experimental, seguro, mesmo sob condições de baixa visibilidade dos meios.

PURPOSE: Retinal photocoagulation under poor visualization condition is often required. Transscleral infrared laser can be used as an alternative to regular transpupillary treatment. Based upon retinographic measurements, we proposed to estimate the reproducibility as well as ocular wall permeability rate for this treatment. Our primary goal was to evaluate whether this technique can deliver adequate photocoagulation at predetermined parameters without direct retinal visualization. METHODS: In New Zealand pigmented rabbits, optimal transscleral infrared diode laser settings were administered to the right eye. With the same parameters, transpupillary photocoagulation was repeated in the left eye. Retinographic and clinical examinations were performed immediately and two months later. RESULTS: Ocular wall permeability rate varied between 58.95 and 63.87 percent. Average permeability using a power of 300 mW (63.14 percent) was found to be higher than that encountered before its enhancement up to 500 mW (59.11 percent), (P<0.05). CONCLUSIONS: Setting parameters showed dose-response effect. No retinal hole or retinal detachment was noticed in any rabbit. Transscleral infrared photocoagulation appeared to be a reproducible and secure method in the experimental model.

Estudo do buraco macular fechado cirurgicamente: avaliação da relação entre a integridade da camada de fotorreceptores e a acuidade visual final por meio da tomografia de coerência óptica / Optical coherence tomography evaluation of surgically closed macular holes: photoreceptor layer analysis and its correlation with final visual outcome

O objetivo deste estudo foi correlacionar a integridade da camada dos fotorreceptores da retina com a visão final obtida em pacientes operados de buraco macular idiopático. Foram colhidas imagens tomográficas da região foveal de 39 olhos de 37 pacientes operados com sucesso a mais de um ano. Dados adicionais pré-operatórios como o tamanho do buraco, tempo de duração da doença e acuidade visual inicial também foram obtidos. Os olhos foram divididos em três grupos por ordem crescente de integridade da camada dos fotorreceptores. Os olhos pertencentes ao grupo de maior integridade apresentaram acuidade visual final significativamente superior aos alocados no grupo de menor integridade. As características iniciais dos buracos não se relacionaram com o resultado visual final. Concluiu-se que uma maior integridade da camada de fotorreceptores exerce papel importante na recuperação da visão em pacientes operados de buraco macular...

The objective of this study was to correlate the integrity of the retinal photoreceptor layer with final visual acuity in successfully operated macular hole patients. Using optical coherence tomography, foveal images were obtained from 39 eyes of 37 patients. Additionally, lesion pre-operative data was collected involving initial visual acuity, lesion size and time duration of the symptoms. All eyes were then included in one of three groups according to their photoreceptor integrity. Optical coherence tomography data obtained shown that those eyes included in the group with better integrity presented superior visual acuity when compared to the other groups. The results were statistically significant. Baseline lesion characteristics did not correlate with a better outcome. In conclusion, post-operative integrity of the photoreceptor layer plays an important role in achieving good visual recovery in macular hole surgery...

Ultraestructura de la retinopatía causada por la hiperoxia en ratas en desarrollo / Ultra structure of retinopathy induced by hyperoxia in developing rats

In order to evaluate the effect of postnatal hyperoxia on retinal structure, newborn rats were exposed to different oxygenation intervals (80 ± 1%) with three interruptions of 21% (30 min each). Four groups of rats were exposed from birth to the 6th, 9th, 12th and 14th postnatal day, respectively and another group was placed under normoxia. After this period all oxygenated groups and the controls remained under normoxia until they were 30 days old for the structural analysis of retina. Retinal histology was carried out using conventional techniques for transmission electron microscopy (TEM). In the ganglion cell layer of the retina from rats exposed for 9 days to hyperoxia, capillaries with large projections toward the lumen, were observed as a possible consequence of cellular edema of endothelium. The most severe damage was observed in rats exposed to hyperoxia during 12 and 14 days, showing mitochondrias swollen up and without crests in the areas surrounding the capillaries, necrosis and apoptosis processes, dense bodies, cells with swollen cytoplasms and rupture of the plasmatic membrane. The results suggest that postnatal hyperoxia causes severe damages to the retina in developing rats with a direct relationship between the time exposed to oxygen and ultra structural damages.

Con el propósito de evaluar el efecto de la hiperoxia posnatal sobre la estructura retiniana se analizaron retinas de ratas recién nacidas expuestas a diferentes periodos de oxigenación (80 ±1%), con tres interrupciones de 21% (30 min c/u). Cuatro grupos de ratas fueron expuestas desde su nacimiento hasta el 6to, 9no, 12mo y 14to días de vida y otro grupo fue mantenido en normoxia. Después de este periodo tanto los grupos expuestos a la hiperoxia como los controles permanecieron en normoxia hasta una edad de 30 días para el análisis estructural de la retina. La histología se hizo usando técnicas convencionales para microscopía electrónica de transmisión (MET). En la capa de células ganglionares de la retina de ratas expuestas a nueve días de hiperoxia, se observaron capilares con notables proyecciones hacia la luz, posiblemente como consecuencia de edema celular del endotelio. El daño más intenso fue observado en las ratas expuestas a hiperoxia durante 12 y 14 días, mostrando mitocondrias hinchadas y sin crestas en las áreas circundantes a los capilares, procesos de necrosis y apoptosis, cuerpos densos, células con citoplasmas hinchados y con ruptura de la membrana plasmática. Los resultados sugieren que la hiperoxia posnatal causa graves daños a la retina en las ratas en desarrollo, con una relación directa entre el tiempo de exposición al oxígeno y los daños ultraestructurales.

Photoreceptor cell apoptosis of rat's retina induced by N-methyl-N-nitrosourea / 中华眼底病杂志

Objective To investigate the mechanism of the toxic effect of N-methyl-N-nitrosourea (MNU) on photoreceptor cell apoptosis of rat′s retina. Methods Thirty 50-day-old female Sprague-Dawley ( SD ) rats were intraperitoneally injected with MNU (60 mg/kg) and were put to death by dislocation of cervical vertebra 12, 24, 48, and 72 hours and 7 days after the injection, respectively. The photoreceptor cell apoptosis was detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and transmission electron microscope. The expression of proliferating cell nuclear antigen (PCNA), vimentin and glial fibrillary acidic protein (GFAP) was detected at different time after injection by immunohistochemical methods. Results The apoptotic index of the retina in the posterior pole was (33.6?2.3)%, (46.5?5.7)%, (20.1?5.3)%, (8.2?3.6)% and (2.5?1.3% at the 12th, 24 th, 48 th, and 72nd hour and on the 7th day, respectively, after injection. Karyopyknosis was found in most photoreceptor cells 24 hours after injection. The expression of PCNA was found in internal granular layer and between internal granular layer and choroid 24 hours after injection, reached the peak after 72 hours, and reduced obviously after 7 days. The positive expression of GFAP and vimentin was found in internal and external granular layer 24 hours after injection, reached the peak after 72 hours, and reduced obviously after 7 days. Conclusion MNU may selectively lead the photoreceptor cell apoptosis and proliferation of M?ller cells.

Apoptosis of photoreceptors in the early stage of siderotic retinopathy in rat eyes / 中华眼底病杂志

Objective To demonstrate if apoptosis is one of the mechanisms of siderotic retinopathy. Methods Autoclaved iron particles were implanted in the vitreous cavities of 32 eyes of SD rats. Glass chips were implanted in 10 control eyes. The experimental eyes were enucleated at various time intervals from days 1 to 15. Retinal degeneration was examined using the TdT mediated, dUTP biotin nick end labeling (TUNEL) method. Electrophoresis on agarose gel was used to detect internucleosomal DNA fragmentation. Results TUNEL positive nuclei were observed only in the outer nuclear layer beginning on day 2. The nuclei spread throughout the outer nuclear layer by the end of day 3. No TUNEL positive nuclei were observed in other layers throughout the experimental period. Analysis of DNA, extracted from the retinas by electrophoresis on agarose gel, revealed a typical ladder pattern of internucleosomal DNA cleavage in the experimental eyes. Conclusions Apoptosis of photoreceptors occurs at the early phase of iron induced retinopathy in the rats.

The Temporary Inerement of the Intraoeular Pressure: The Effect on the Retina

After the intraocular bleeding was inuced by amputation of the rabbit retinal artery, the level and duration of the level of the intraocular pressure to control the bleeding was studied. Then, the eyes were enucleated and evaluated for the effect of the increased intraocular pressure. In 3 of 4 eyes studied, the bleeding is controlled at the height of 140-145 cm of the infusion bottle for 10 seconds. And the maintenance of the height of 125 cm for 15 seconds was effective in one eye. Although the expanded intercellular space in the outer nuclear layer, destruction of the photoreceptors and formation of the vacuoles appeared in the first week, they were only the temporary findings for they disappeared after second week. In the rebbit, the retinal arterial bleeding is able to be controlled at the level of about 100 mmHg of the IOP for about 10 seconds effectively and safely.

THE DAY AND NIGHT CHANGES OF THE PHOTORECEPTORS IN THE COMPOUND EYE OF THE HORSEFLY ( TABANUS MANDARINUS) / 解剖学报

The changes of the ultrastructure of the photoreceptors in the compound eye of horsefly (Tabanus mandarinus) were observed electromicroscopically at both the mid-day and mid-night. We found that there were various structural changes in cones, pigment cells, retinula cells, rhabdomeres at the two different times.The functional significance of the day and night changes of the photoreceptors and their relations to natural light illumination were discussed.