Objective To observe the retinal ultrastructure of the human fetal at the age of 9 months, and to investigate the clinical significance of the observation on retinal neuron development during the prenatal period.Methods Four human fetal eyes of 2 fetus at the gestational age of 9 months, including 1 at 35 and the other at 36 weeks, were obtained after termination of pregnancy due to trauma. The gestational ages of the fetus were estimated according to both last menstrual period (LMP) of the pregnant women and the weight/crownheel length of fetus at the delivery. From each eyeball, 4 pieces of retina at the posterior pole were obtained and observed after specimens handling according to the procedure of routine electron microscopy. Eight pieces of retina which were randomly selected from total of 16 pieces of retina in each group were processed and observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Permissions from pregnant women and family members were guaranteed.Results At the gestational age of 9 months, the outer nuclear layer of fetal retina contained 5 to 6 layers of photoreceptor cells (PRC), and sphericallike membrane structures were found outside of the outer limiting membrane (OLM). Among many tightaligned inner segments of PRCs there was zonula adherens of OLM, mitochondrias at inner side of OLM, and cilium at outer side of OLM. Outer segment of PRCs were short and contained a few irregularly arranged disc membrane. Some PRC had a multishaped nucleus in which equal amount of euchromatin and heterochromatin. There were only few and thin axon branches from photoreceptor cells, and very few axons contacted with inner nuclear layer (INL) and no typical synapse was found. The INL contained 4 to 5 layers of cell bodies, in which many cellular nuclear had uneven density of euchromatin and heterochromatin; some were lobulated nucleus with clear karyotheca. In inner plexiform layer (IPL), the nerve cells had small branches, and only little connection among the synapses and few synapse structures were found. Although not many retinal ganglion cells (RGC) existed,RGC had both intact cell membrane and some rough endoplasmic reticulum (RER).The karyotheca of RGC had double-layers structures, and the nucleus was mainly consisted of euchromatin. Internal limiting membrane (ILM) had doublelayer membrane structures, and the wellarranged nerve fiber layer was located at the outer side of ILM, with some micropores on the surface. Conclusions At the gestational age of 9 months, all layers of the human retinal has been formed, but some cell structure and cell connections are not yet mature, suggesting that at this time of period, human retina is still at an important stage of developing and remodeling.
ObjectivesTo evaluate the reproducibility of Heidelberg retina tomograph (HRT) macular edema module(MEM) measuring the macular retinal thickness.MethodsSixty-two healthy volunteers (9-68 years old) were examined by HRT-II procedure. The retinal signal width (SW) at macula and fovea and macular edema index (E) were recorded for t-test, Pearson linear-correlation analysis. Intra-subject variation repeatedly measured was analyzed with coefficient of variation, 95% tolerance limits of change (TC), and intraclass coefficient of correlation (ICC). ResultsIn healthy individuals, retinal SW was (0.734±0.236) mm at macula，and (0.781±0.243) mm at fovea; macular E was (1.169±0.619). The coefficient of variation repeatedly measured: retinal SW was (8.7±68)%，retinal SW at the fovea was (8.5±6.7)%, and the average was (15.6±13.9)%; 95%TC of intra-subject sequential repeated measurement was 0.131 (8.9%) of retinal SW, 0.137 (10.5%)of fovea SW，and 0.198 (7.4%) of average E. ICC of one individual repeatedly measured by one operator was 0.950 of macular SW, 0.949 of fovea SW, and 0.898 of average edema index.ConclusionsHRT-II MEM is noninvasive, fast and highly reproducible, which provides a new technique to monitor the objective quantification of macular diseases related to retinal thickness. ( Chin J Ocul Fundus Dis, 2005,21:103-105)
Diabetic retinopathy (DR) is one of the most common causes of visual impairment and blindness in diabetic patients. It is particularly important to set up simpler, safer, non-invasive and highly effective methods for diagnosis as well as monitoring DR. A variety of new fundus imaging techniques show great advantages in early diagnosis, treatment and monitoring of DR in recent years. The main characteristics of wide-field scanning laser imaging system is achieving a large range of retinal image in a single photograph and without mydriasis. It provides several options for color images, FFA and FAF, which satisfy to detect the retina, choroid and vascular structure. Multi spectral fundus imaging system is suitable for DR screening, because it is able to recognize the typical characteristics of DR, such as microaneurysms, hemorrhage and exudation, and is non-invasive and convenient. OCT angiography is a quantitative examination that provides foveal avascular zone area, macular blood flow density, which provides strong evidence for DR diagnosis. The improvement of these new techniques will help us to build up a personalized evaluation system of DR.
Purpose To verify the effectiveness of combined B-scan ultrasonoscopy and ultrasound biomicroscopy(UBM)imagings in diagnosis of retinal detachments. Methods To contrast the manifestations in vitrectomy operations with the findings of preoperative combined B-scan ultrasonic and UBM examinations in 25 eyes of 25 cases in which 18 eyes with rhegmatogenous retinal detachment and 7 eyes with traumatic retinal detachment were included. Results B-scan ultrasonic imagings were divided into four types: type C,type V,type upsilon; and type gamma;,which included 6 eyes,2 eyes,4 eyes and 11 eyes respectively,and from type C to type gamma;,the retinal detachments manifested themselves from simple posterior segment proliferative vitreoretinopathy(PVR)to both anterior and posterior PVR.The imagings of UBM were divided into 3 types:shallow retinal detachment,retinal circumferential contraction and retinal anterior displacement,which reflected the degree of anterior PVR from lightness to severeness. Conclusions The technique of combined B-scan ultrasonoscopy and UBM can be used to access the severity of the retinal detachments,hence would be beneficial in diagnosing anterior and posterior PVR,designing the surgical precedures and assessing the prognosis. (Chin J Ocul Fundus Dis,1998,14:16-20)