PURPOSE:To examine the role of apoptosis in photoreceptor cells degeneration process in Pathologic myopia.
METHODS: Nine human eyes with pathologic myopia were studied by
histopathologic and TDT-mediated biotin-dUTP nick-end labelling (TUNEL) techniques.
RESULT:The characteristic DNA fragmentation of apoptosis was observed in scattered photoreceptor cells in 4 of 9 eyes.
CONCLUSION:The results suggested that apoptosis is one of the pathways of photoreceptor cells death in retinal degeneration of pathologic myopia.
（Chin J Ocul Fundus Dis,1996,12: 144-146 ）
Objective To investigate the iconographic characteristics and clinical significances of synchronic examination of indocyanine green angiography (ICGA) and fundus fluorescein angiography (FFA) for high myopia.Methods Thirty patients (57 eyes) with high myopia（gt;-6.00D）, selected randomly and consecutively, were examined by ICGA and FFA synchronically.Results The result of early phase of FFA showed hypofluorescence of the background in 25 eyes，while of late phase showed subretinal neovascularization (SRNV) in 10 eyes and streak formation in 40 eyes. The result of ICGA showed choroidal retrobulbar arteries in 8 eyes, hypofluorescence of the background in 35 eyes, SRNV in 8 eyes, and streak formation in 52 eyes.Conclusion The iconographic characteristics of ICGA and FFA of high myopia include hypofluorescence of the background, SRNV and streak formation. ICGA can givemore exact information on the lesions of choroid in high myopia. The synchronic examination of ICGA and FFA may act as a guide to the therapy for high myopia.(Chin J Ocul Fundus Dis，2003，19：87-89)
ObjectiveTo evaluate the effect of form deprivation myopia on optic nerve head and retinal morphology in guinea pigs using optical coherence tomography (OCT).
MethodsTwenty guinea pigs aged from 4 to 5 weeks were chosen and randomly divided into the experimental group and control group, with 10 guinea pigs in each group. Form deprivation myopia was established for the right eyes of guinea pigs in experimental group for 4 weeks. The guinea pigs of control group were not intervened. Before and 4 weeks after form deprivation, refraction was measured by retinoscopy after cycloplegia; the axial length was measured by A-scan ultrasound; retinal nerve fiber layer (RNFL) thickness, optic nerve head and retinal morphology of guinea pigs were analyzed using OCT.
ResultsBefore form deprivation, there were no statistically significant differences in spherical equivalent, axial length, RNFL thickness, disc edge area, optic disc area, average cup disc ratio, vertical cup disc ratio, cup volume, retinal thickness, or retinal volume between the experimental group and control group of guinea pig (P > 0.05). After 4 weeks of form deprivation, RNFL thickness of (64.9±17.7) μm in guinea pigs in experimental group was thinner compared to (97.9±25.1) μm in control group (t=-2.845, P=0.015). Retinal thickness of (142.7±3.4) μm in guinea pigs in experimental group was thicker compared to (138.4±3.5) μm in control group (t=2.338, P=0.038). There were no significant differences in disc edge area, optic disc area, average cup disc ratio, vertical cup disc ratio, cup volume or retinal volume between groups (P > 0.05). There were statistically significant differences in spherical equivalent, axial length, RNFL thickness, vertical cup to disc ratio cup volume, and retinal thickness between after and before form deprivation in the right eye of guinea pigs in the experimental groups (t=46.001, -50.119, 5.385, 3.447, -2.814, -8.911; P < 0.05), while there were no statistically significant differences in disc edge area, optic disc area, average cup disc ratio, or retinal volume (P > 0.05).
ConclusionForm deprivation myopia has an effect on RNFL and retinal thickness.
Peripapillary intrachoroidal cavitation (PICC) is a common pathological change observed in high myopia. The exact pathogenesis of PICC is still unclear. Expansion and mechanical stretching of the peripapillary sclera, breakage and defect in the retina near the border of the myopic conus and communication between intrachoroidal cavity and the vitreous space may be important segments during the development of PICC. Color fundus photography shows a localized and well-circumscribed peripapillary lesion with yellow-orange colour, often accompanied by fundus changes, such as myopic conus excavation, optic disc tilting and inferotemporal retinal vein bending at the transition from the PICC to the myopic conus. However, the PICC lesion is not easy to be recognized in the fundus photography. Fluorescein angiography shows early hypofluorescence and later progressively staining in the lesion. Indocyanine green angiography shows hypofluorescence throughout the examination. Optical coherence tomography (OCT) is vital in diagnosing PICC. Hyporeflective cavities inside the choroid, sometimes communicating with the vitreous chamber, can be observed in OCT images. OCT angiography indicates lower vessel density or even absence of choriocapillary network inside or around PICC lesions.
ObjectiveTo investigate the effects of form deprivation on the morphology of different types of RGC in mice.MethodsSixty B6.Cg-Tg (Thy1-YFP) HJrs/J transgenic mice were randomly assigned to form-deprived group (n=28) and control group (n=32). The right eyes of mice in the form-deprived group were covered by an occluder for 2 weeks as experimental eyes. The right eyes of mice in the control group were taken as control eyes. Before and 2 weeks after form deprivation, the refraction and ocular biometrics were measured; RGC were stained with Bra3a antibody and counted; the morphology of RGC was reconstructed with Neuroexplore software after immunohistochemical staining. The data was compared among experimental eyes, fellow eyes and control eyes by one-way analysis of variance.ResultsTwo weeks after form deprivation, the axial myopia was observed in the experimental eyes (refraction: F=15.009, P＜0.001; vitreous chamber depth: F=3.360, P=0047; ocluar axial length: F=5.011, P=0013). The number of RGC in central retina of the experimental eyes was decreased compared with the fellow eyes and the control eyes (F=4.769, P=0.035). The reconstructed RGC were classified into 4 types according to their dendritic morphology. Form deprivation affected all 4 types of RGC but in a different way. Among them, 3 types of RGC were likely contribute to form vision perception. Form deprivation increased the dendrite branches in these types of ganglion cells. However, form deprivation decreasd dendrite segment numbers in both eyes and the intersection and length insholl analyse type 4 ganglion cells which were morphologically identified as ipRGC.ConclusionForm deprivation distinguishingly affects the morphology of different types of RGC, indicating that form vision and non-form vision play different role in myopia development.
Dome-shaped macula (DSM) of high myopia has been described as an inward convexity or bulge of the macular within the concavity of the posterior staphyloma in highly myopic eyes, with the bulge height over than 50 μm, which can be observed by optical coherence tomography. There are three patterns of DSM, including the typical round dome, the horizontally oriented oval-shaped dome and the vertically oriented oval-shaped dome. The pathogenesis of DSM development remains unclear, several hypotheses have been suggested, such as localized choroidal thickening in the macular area, relatively localized thickness variation of the sclera under the macula, resistance to deformation of sclera staphyloma, ocular hypotony and tangential vitreoretinal traction. Vision-threatening macular complications of DSM including serous retinal detachment, choroidal neovascularization, foveoschisis and retinal pigment epithelial atrophy. Clinically, asymptomatic patients with DSM mainly take regular follow-up observation. Appears serous retinal detachment and significant visual impairment, treatment with half-dose photodynamic therapy, supplementary of laser photocoagulation or oral spironolactone may have a beneficial effect. However, more large clinical studies are required to confirm the exact efficacy of these treatments.
The fundus lesions caused by high myopia (HM) often lead to irreversible visual impairment or even blindness. However, the pathogenesis of HM and its fundus lesions is still unclear, the intraocular fluid detection technology of micro samples has brought new prospects for the early diagnosis, monitoring and intervention of the fundus lesions. The molecules associated with HM are various and functionally diverse, intermolecular interactions are staggered and the specific mechanism is complex. With the development of intraocular fluid detection technology, while gradually revealing the role of each molecule in the pathogenesis of HM, it is expected to successfully assist clinical work in the future, providing outpost markers for the progress of myopia and targets for early intervention, or providing a new therapy choice for HM fundus lesions at the molecular level targeting pathogenesis, which is expected to provide more accurate and effective treatment for HM patients in the future.
Objective
To evaluate the successful rate of surgical treatment of retinal detachment due to macular hole in high myopia, and to analyze the relative reasons.
Methods
Eleven eyes of 11 high myopic patients with retinal detachment due to macular hole underwent vitrectomy combined with the adjunct of 18% C3F88or silicone oil. Strict prone position was conducted at least 2 weeks postoperatively.
Results
Macular hole closed and retina reattached in 10 eyes. Visual acuity was increased in 10 eyes, and no change in 1 eye. Postoperative complications mainly included nuclear sclerosis of the lens(1 eye), intraocular pressure elevation (1 eye), fibrosis exudates (2 eyes)，and diplopia (1 eye).
Conclusion
The use of vitrectomy combined with the adjunct of 18% C3F8or silicone oil is a safe and effective method in treating retinal deta chment due to macular hole in high myopia. Preoperative careful examination of o cular fundus, rational surgical design, and better surgical expertise are basic factors in treating this disease.
(Chin J Ocul Fundus Dis, 2001,17:90-92)
Objective
To study the global and histological changes of myopia and explore its pathogenic mechanism.
Methods
Chicks were reared with monocular suture of eyelid. When myopia had been confirmed by optometry, eyeballs were removed and subjected subsequently to measurement and light and electron microscopies.
Results
Three dimensions in the eyeballs of suture group were all enlarged markedly and the mean diopter was -15.00D. Under the light microscope, rod outer segment elongated and connected With PREC in suture group. With micrometer measure, cartilaginous sclera thickened and retina became thinner. Under electron microscope, rod outer segment elongated and membrane disc was intact. In the cytoplasm of RPEC, the phagosomes containing fractions of the membrane disc of outer segment were remarkably decreased.
Conclusion
Early form deprivation may affect the drop of membrane disc and cause eyeball enlargement; thus, myopia forms.
(Chin J Ocul Fundus Dis,1999,15:20-23)
Myopic traction maculopathy (MTM) is one of the most common macular degeneration in highly myopic eyes, which is the main cause of visual impairment. MTM is a slowly progressing disease. Macular retinoschisis (MRS), macular detachment and macular hole are the three main manifestations of MTM. Under the combined action of various traction mechanisms, MTM may manifest as stable anatomical structure, progressing or spontaneous improvement. The possibility of spontaneous improvement of MTM is small and the degree of improvement of BCVA varies, while the risk of deterioration of MTM increases with its development. Attention should be paid to patient follow-up and timely surgical treatment to prevent MTM from further threatening the patients’ vision in clinically.
