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.
Objective To observe the expression of Nogo66 receptor （NgR）in ratsprime; retina during the postnatal development． Methods The expression of NgR in 48 rats were observed by immunofluorescence histochemistry and laserconfocal microscopy 0, 3, 7, 14, 21, 35, 49, 63 days after birth, with 6 rats in each group, respectively． Results The expression of NgR is positive in the retina in the whole duration of growth, and the fluorescence pigmentation was located around the ganglion cell nuclaear. Conclusion The positive expression of NgR suggests that the interaction of NgR and CNS myelin inhibitors not only inhibit neuronal plasticity but also promote it, which could regulate neuronal plasticity.
Objective To observe the distribution of human photoreceptor cells at the posterior pole, detect the change of density of the cells affected by eccentricity, and analyze the relationship between the density distribution and the visual sensitivity. Methods Twenty human eye cups with the cornea removed were fixed in 4% polyformaldehyde for 1-4 weeks, and the retinal mounts were observed by differential interference contrast microscope to reveal the retinal cellular configuration and density. The inner segments of photoreceptor cells were first observed from the center to the temporal peripheral part of the retinal mounts. Results The highest density of visual cone cells was at the central fovea (134 000-267 000/mm2, mean 198 090/mm2; CV value:18.2%). The density and individual variation decreased rapidly in the peripheral area. The high density area of rod cells was at the 4 mm of the eccentricity, with the highest value of 72 610-182 350/mm2 and with the high density between 3 and 5 mm. Conclusions The inner segment of photoreceptor cells was monolayer, which may tell the cellular absolute value. The high density of retinal cone cells at the central fovea provide the basis of sensitive central visual acuity, which relates to the individual variation and development. The rod cells have the peak density at the eccentricity with 4 mm, and this area has the greatest sensitivity of dim vision.
Objective To observe the effect of scanning laser ophthalmoscope (SLO) measuring macular light sensibility on evaluating the visual function in idiopathic epiretinal membrane (IERM), and analyze the relationship among the macular light sensibility, central visual acuity, and the thickness of fovea. Methods Procedure of microperimetry of SLO was performed on 44 patients (55 eyes) with IERM diagnosed by indirect and direct ophthalmoscope and optical coherence tomography (OCT). The light sensibility at 10deg;macular central area was measured. The results were compared with 31 healthy control eyes which underwent the same examinations simutaneously. The correlation among the macular light sensibility, the thickness of fovea measured by OCT, and the results of logarithm visual acuity was anaylzed. Results Compared with the control eyes, macular light sensibility decreased in IERM eyes significantly (F=47.265, Plt;0.01), which had the positive correlation with the decrease of visual acuity (r=0.687, P=0.000) and negative correlation with the retinal thickness of macular fovea (r=-0.532,P=0.003). The mean macular light sensitivity in patients with metamorphopsia decreased obviously compared with which in patients without (t=7.039, P=0.000). The mean macular light sensitivity in patients with prolifertive IERM decreased compared with which in patients with dropsical IERM without statistical difference (t=-1.706, P=0.094). Conclusion Microperimetry of SLO may sensitively reflect the macular visual function of eyes with IERM and quantificationally evaluate the changes of macular light sensibility. The changes of macular light sensitivity correlates with the central visual acuity and retinal thickness of macular fovea. (Chin J Ocul Fundus Dis, 2006, 22: 100-102)
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)
Objective To observe the dimensions of the capillary blood vessel arch in central fovea of macula and the foveal avascular area (FAZ), and their relationships with age.Methods Retina in macula of 32 cadavers eyes were isolated . Retinal vessels were immunostained by collagen type IV and examined by confocal laser scanning microscopy. The area and diameter of the FAZ were measured, and the relationship between FAZ and age was analysed. Results The parafoveolar capillary network was observed clearly by confocal laser scanning microscopy. The average area of the FAZ was (0.24±0.13) mm2, and the average diameter was (0.54±0.15) mm. The area and diameter of the FAZ did not show any correlation with age.Conclusions The parafoveolar capillary network could be observed by confocal laser scanning microscopy. The size of the FAZ does not change with age. The dimensions of the parafoveolar capillary network may not be influenced by age. (Chin J Ocul Fundus Dis，2003，19：73-75)
Objective To test the hypothesis that the macular pigment may be a marker of foveal cone function and consequently the structural integrity of foveal cones.Methods Sixteen patients (32 eyes) diagnosed to have Stargardt dystrophy and three patients with full thickness macular holes by clinical criteria were studied with a scanning laser ophthalmoscopy (SLO) comparing argon laser blue and infrared images for the presence or absence of macular pigment (MP) in the fovea. An C++ computer based program was used to evaluate the density of MP. Eyes were graded into three categories: those without foveal macular pigment, those with partial pigment and those with normal amounts of macular pigment. These categories were compared with visual acuity determined by the Snellen chart. Results Thirteen eyes with a visual acuity of 20/200 or worse had no macular pigment in the fovea. Eleven eyes with visual acuity of 20/40 or better had a normal amount of macular pigment in the fovea and 1 eye had partial macular pigment. Eleven eyes with partial macular pigment had intermediary acuity value.Conclusions Foveal macular pigment is closely related to foveal cone acuity and therefore may be a marker for the presence of foveal cones. Infrared light is a sensitive indicator of early macular diseases.(Chin J Ocul Fundus Dis，2003，19：201-268)