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 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)
Adaptive optics (AO) is a technique to improve the performance of optical systems by reducing the influence of optical aberrations. Combined with scanning laser ophthalmoscope (AOSLO), the aberration of human refractive system can be corrected. Thus, the resolution and quality of imaging can be greatly improved to the cellular level in vivo retina (such as photoreceptor, nerve fibers, vascular parietal cell), therefore the earlier changes of the diseases can be detected. At the same time, microstructure changes of retinal can also be observed during the follow-up of the disease. Due to inherent technical defects of AOSLO, its wide application in clinical practice is limited. With the continuous progress of AO technology and the further improvement of related software functions, the function of the system will become more stronger and will play a more and more important role in scientific research and clinic.
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)
Purpose To observe the pathologic changes of retinal photic injury in mice. Methods A light damaged trunk was designed by ourselves.The mice were given an intermitent light exposure for 3 days,12 hours light exposure every day and 12 hours dark adaption before every exposure.Experimental animals were sacrificed on the 1st,6th,12th,18th and 30th day after light injury,and the eyes were enucleated for light and electronic microscopy observation. Results The early pathologic changes including disc membrance swelling,disorganization in outer segments,and mitochondrial swelling,spherical change in inner segments．Then the chromatin densification,liquefaction and margination,and the shrinkage of nuclear membrance were found in the nuclear layer.Finally the outer nuclear layer became thin and disappeared.The apical microvill of RPE cell disappeared and basic fold became flat in some samples. Conclusion The photoreceptor degeneration was the pathologic characteristic of retinal photic injury in mice. (Chin J Ocul Fundus Dis,1998,14:215-218)