Retinal Changes in White Rabbits after Exposure to the Light of an Operating Microscope

PURPOSE: This study was performed to investigate the potential damage to white rabbit retinas caused by an operating microscope light. METHODS: A total of 18 white rabbits were exposed to the light of an operating microscope for 60 minutes. Fundus examination, fluorescein angiography (FAG), and electroretinogram (ERG) were performed before exposure and 1 hr, 1 day, 7 days and 14 days afterward to allow for serial comparisons. Light and electron microscopic examinations were performed to evaluate the changes in the rabbit retinas over time. RESULTS: Signs of retinal damage upon fundus examination and FAG were not found before or after exposure to the light of an operating microscopy. ERG, however, showed significant reduction in the dark-adapted rod response 1 hour after light exposure, and significant decline in the amplitude of the maximal combined response a- and b-wave 1 day after light exposure in the rabbit retinas. ERG findings returned to the pre-exposure level after 2 weeks. Ultrastructural injury to the photoreceptor outer segments and the retinal pigmented epithelium, observed using transmission electron microscopy, recovered to the pre-exposure state after 2 weeks. CONCLUSIONS: The risk of retinal damage should be considered as an early result of exposure to the light of an operating microscope, even in normal retinal findings.

The Effects of Intravitreal Bevacizumab Injection According to the Type of Diabetic Macular Edema

PURPOSE: To investigate the effects of intravitreal bevacizumab injection on diabetic macular edema (DME) of different types classified using Optical Coherence Tomography (OCT). METHODS: A total of 82 eyes with refractory DME were enrolled. The DME was classified into diffuse, cystoid, or serous type based on the OCT findings. All cases had received an intravitreal injection of 1.25 mg bevacizumab each month for three months. Foveal thickness, macular volume, and best corrected visual acuity (BCVA) were measured before and one month after the injection, and the interval changes in these parameters were compared. RESULTS: The types of DME were classified as follows: diffuse macular edema 50%, cystoid macular edema 31.7%, and serous macular detachment 18.3%. Foveal thickness and total macular volume after intravitreal bevacizumab injection decreased in all types, and the cystoid and serous types showed better response than did the diffuse type with regard to foveal thickness. However, there were no significant differences in the extent of the change in total macular volume or BCVA among the three types of DME. CONCLUSIONS: There were differences in the therapeutic effects of intravitreal bevacizumab injection among the different types of DME classified using OCT. These differences may be associated with the stabilizing effect of the bevacizumab. This effect was stronger with regard to vascular permeability, the primary factor in the pathogenesis of the cystic and serous types, than with regard to leakage from the microaneurysm, the primary factor in the pathogenesis of the diffuse type. Practical application of bevacizumab to eyes with different DME types will help in further evaluating intravitreal bevacizumab injection as a treatment option for DME.

A Case of Subretinal Hematoma Secondary to Polypoidal Choroidal Vasculopathy Misunderstood as a Subretinal Mass

PURPOSE: To report a case of subretinal hematoma secondary to polypoidal choroidal vasculopathy (PCV) misunderstood as a subretinal mass. CASE SUMMARY: A 73-year-old man with no specific medical history visited our clinic with decreased vision in the right eye. Slit-lamp examination revealed no specific findings for the anterior segment of the right eye. Upon fundus examination, an elevated macular lesion with some subretinal hemorrhages was observed, and a subretinal mass lesion was found on ultrasonography. After performing fluorescein angiography, indocyanine green angiography, and magnetic resonance imaging, we presumed that this lesion was a subretinal hematoma or ocular tumor and recommended observation. One month later, the subretinal mass had decreased in size. One year later, PCV with large retinal pigment epithelial detachment (RPED) was observed. After the intravitreal bevacizumab injection, RPED and macular edema were improved. CONCLUSIONS: We confirmed PCV with a subretinal hematoma and large RPED which seemed to be a subretinal mass and was difficult to differentiate from ocular tumors.

Peripapillary Retinal Nerve Fiber Layer Thickness Change After Panretinal Photocoagulation in Patients With Diabetic Retinopathy

PURPOSE: To examine the effect of panretinal photocoagulation (PRP) on the retinal nerve fiber layer (RNFL) thickness in patients with diabetic retinopathy. METHODS: Subjects included 118 eyes for a treatment group and 164 eyes for a control group. The peripapillary RNFL thickness was measured before and 6 months after PRP in treatment group. In control group, the peripapillary RNFL thickness was measured at baseline and 6 months later. The relationships between changes in RNFL thickness and the number of laser burns, duration of diabetes, HbA1c level, and vision change were analyzed. RESULTS: After 6 months, the RNFL thickness decreased an average of 2.12 microm and 0.93 microm in the treatment and control groups. However, the changes between the two groups were not statistically significant. The relationship between the number of laser burns and changes in RNFL thickness was not significant. No differences were found between changes in the RNFL thickness and the duration of diabetes in either group. However, in the treatment group a higher HbA1c level was correlated with a greater decrease in post-PRP RNFL thickness. This relationship was not observed in the control group. The difference in the change of the RNFL thickness between the two groups was statistically significant. Vision increased an average of 0.02 and 0.01 after 6 months in the treatment and control groups, respectively. However, this difference was not statistically significant. CONCLUSIONS: Although a decrease in peripapillary RNFL thickness was observed in the treatment group after 6 months, it was not statistically significant compared to control group. However, the decrease was greater when the blood HbA1c level was higher.

Analysis of the Optic Nerve Head and RNFL Thickness Using Optical Coherence Tomography in Diabetes

PURPOSE: Retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) in diabetic patients with normal tension were analyzed using optical coherence tomography (OCT), which revealed that diabetes induce morphologic changes in optic disc and RNFL thickness. METHODS: A total of 192 patients with type 2 diabetes were analyzed with fundus examination and classified as having normal retina, mild - moderate, severe nonproliferative retinopathy (NPDR), or proliferative retinopathy (PDR). These patients were evaluated with OCT and compared with normal control group. RESULTS: The mean average thickness and nasal average thickness of RNFL in mild-moderate, and severe NPDR groups decreased compared with those of the other groups. There was an increase in the temporal average thickness of RNFL in the PDR group. As the duration of diabetes increased, the mean average and nasal average of RNFL thickness also decreased. The severity of diabetic retinopathy didn't show statistically significant differences in a topographic analysis of the optic nerve head. CONCLUSIONS: The mean average thickness and nasal average of RNFL decreased in NPDR groups. Diabetic changes should be considered when diabetes patients are diagnosed with glaucoma or glaucoma progression.

Comparion of Surgical Result by IOL implantation Time in Simultaneous Lens Extraction and Vitrectomy

PURPOSE: To compare the surgical results according to the IOL implantation time in patients who were performed simultaneous lens extraction, vitrectomy and silicone oil endotamponade. METHODS: We reviewed the medical records of 60 eyes in 57 patients with vitreoretinal diseseases. The group I included 32 eyes those were performed simultaneous lens extraction, vitrectomy and silicone oil endotamponade as the first surgery, and sequential IOL implantation at the time of silicone oil removal as the second surgery. The group II included 28 eyes those were performed simultaneous lens extraction, vitrectomy, silicone oil endotamponade and IOL implantation as the first surgery, and sequential oil removal as the second surgery. The cases were evaluated 6 months after silicone oil removal. Anatomical and functional success rate, difference of postoperative predictive refraction, postoperative complication occurrence rate were compared between two groups. RESULTS: The anatomical successes were achieved in 93.8% (30/32 eyes) and 92.9% (26/28 eyes) in the group I and II respectively. The functional successes were achieved in 71.9% (23/32 eyes) and 78.6% (22/28 eyes) in the group I and II respectively. The differences between preoperative predicted target refraction and postoperative final refraction were 0.68D and 0.92D in the group I and II respectively. The incidence of postoperative anterior chamber reaction and secondary glaucoma were significantly high after second surgery in the group I. CONCLUSIONS: We recommend a simultaneous implantation of IOL at the combined surgery of lens extraction and vitrectomy with silicone oil endotamponade to reduce postoperative complications.

A Case of Enterococcus Faecalis Endophthalmitis after Phacoemulsification

PURPOSE: To report a case of Enterococcus faecalis endophthalmitis which occurred two days after phacoemulsification and posterior chamber intraocular lens implantation. A vitrectomy performed during the early stage of infection showed retinal and vitreous presentation. We report the clinical manifestation, operative findings, and treatment of this pathogen. METHODS: A healthy, 71-year-old female, presented with a sudden loss of vision and eyeball pain two days after phacoemulsification and intraocular lens implantation. As inflammation of the anterior chamber and vitreous cavity progressed rapidly, we performed intravitreal antibiotics injection (Amikacin, 0.4 mg/0.1 ml, Vancomycin, 1 mg/0.1 ml). Since this was ineffective, pars plana vitrectomy, silicone oil tamponade, and intravitreal antibiotics injection (Vancomycin, 1 mg/0.1 ml) were performed. During the procedure, we noted that the vitreous humor was cloudy and apparently filled with pus. We also noted an edematous retina with hemorrhages and necrotic changes. Enterococcus faecalis was identified on vitreous and aqueous fluid culture. RESULTS: Twelve weeks after vitrectomy, her corrected visual acuity was hand motion and there was no evidence of recurrence.

Effect of DA-8159, a Selective Phosphodiesterase Type 5 Inhibitor, on Electroretinogram and Retinal Histology in Rabbits

DA-8159, a selective inhibitor of phosphodiesterase type 5, was developed as a new drug for erectile dysfunction. The effect of DA-8159 on the electroretinogram (ERG) and the retinal histopathology were evaluated in rabbits. The ERG was performed prior to, and 1 and 5 hr after DA-8159 (5 to 30 mg/kg) administration. The plasma concentration of DA-8159 was determined at each time point, and retinal microscopic examination was also performed. There was no statistically significant ERG change at any dose or at any time. Though the 30 Hz flicker showed a prolongation of the implicit time at 5 hr after the administration of either DA-8159 15 mg or 30 mg/kg (p<0.05), but concurrent amplitude decreases were not statistically significant. At a dose of 5 mg/kg, no test drug was detected in the blood after either 1 or 5 hr. At either 15 mg/kg or 30 mg/kg, there was a dose-dependent increase in the blood concentration after 1 hr of drug administration, which decreased with time. In light and electron microscopic examinations of the retina, there was no remarkable change at any dose. These results suggest DA-8159 has a low risk potential to the retina, but further evaluation on the visual functions in human is needed.

The Effects of Glucose on the Expression of MMP and TIMP in Cultured Retinal Pigment Epithelial Cells

This study evaluated the effects of glucose in human retinal pigment epithelial (RPE) cells to investigate the cause of diabetic retinal complications. Human RPE cells were cultured in media containing 5.5 mM, 11.0 mM, and 16.5 mM D-glucose. The present study performed proliferation and migration assays, and conducted western blotting for the protein expression, as well as RT-PCR for the mRNA expression, of MMP-2 and -9, and TIMP-1 and -2. The results of the western blotting analysis showed that increasing glucose concentration significantly increased the expression of MMP-2 and -9, but significantly decreased the expression of TIMP-1 and -2. Moreover, the RT-PCR results indicated significant increases in the mRNA expression of MMP-2 and -9, as well as of TIMP-1 and -2, by raising glucose concentration. This study provides fundamental data for future research on the mechanism of retinal complication in diabetic patients.

Relationship between Diabetic Retinopathy and Arteriolosclerosis in Patients with NIDDM (Non-insulin-dependent diabetes mellitus)

PURPOSE: To evaluate the correlation between diabetic retinopathy (DR) and arteriolosclerosis in patients with NIDDM (non-insulin-dependent diabetes mellitus), to investigate the risk factors of DR, and to assess the change of the correlation according to the risk factors. METHODS: The study subjects were selected from consecutive routine clinical visits by random sampling from July 2002 to June 2003. The patients were divided into two groups according to the presence of DR, and the patients' charts, fundus examination and blood test were retrospectively reviewed. ETDRS (Early Treatment DR Study) classification for DR and Scheie classification for arteriolosclerosis were used. Statistical analysis was conducted with SPSS program (version 10.0). The confidence interval was set to 95%, and the level of significance was set at p=0.05. RESULTS: DR had a statistically significant correlation with arteriolosclerosis, especially according to duration of diabetes mellitus (p<0.05). Risk factors including diabetes mellitus duration, HgA1c level, and LDL (low-density lipoprotein) cholesterol level showed statistically significant difference (p<0.05). CONCLUSIONS: From the result of analysis, DR has a statistically significant correlation with arteriolosclerosis, especially according to the duration of diabetes mellitus. To prevent vision-threatening complications of DR, the degree of arteriolosclerosis as well as risk factors such as diabetes mellitus duration, serum HgA1c level, and LDL (low-density lipoprotein) cholesterol level should be carefully considered and monitored in the evaluation, progression, and treatment of DR.

Suppression of VEGF by Aminoguanidine in RPE Cells Cultured in the Hyperglycemic Condition

PURPOSE: We evaluated whether aminoguanidine could inhibit VEGF mRNA expression in the retinal pigment epithelial cells cultured at various glucose concentrations. METHODS: Human retinal pigment epithelial cells were cultured in the culture media containing 5.5 mM, or 11 mM, or 16 mM glucose for 5 days, or 7 days, or 14 days respectively. To evaluate an inhibitory effect of aminoguanidine on VEGF mRNA expression, 1 micro M, or 3 micro M, or 10 micro M aminoguanidine was added in the culture media. The VEGF mRNA expression was assayed by northern blot analysis. RESULTS: The VEGF mRNA expression of the cultured retinal pigment epithelial cells increased proportionally with media glucose concentration in culture media. At each glucose concentration of the media, VEGF mRNA expression increased with a prolongation of incubation period. An aminoguanidine inhibited the expression of VEGF mRNA by concentration-dependent manner in 5 day and 7 day incubation, but not in 14 day incubation. CONCLUSIONS: The aminoguanidine could inhibit a new vessel formation in the diabetic retina, and be useful for therapeutic or preventive drug in the diabetic retinopathy.

Results of Silicone Oil Endotamponade and Analysis of Its Prognostic Factors

PURPOSE: Combined with vitreoretinal surgery, silicone oil endotamponade has become a standard technique and improved the prognosis of complex retinal diseases. To improve success rate of silicone oil endotamponade, the authors analysed complications and associated with other variables. METHODS: The authors analysed 90 cases of silicone oil endotamponade (102 eyes), all operated by one surgeon from 1995 to 2000 and followed-up over 6 months. The series consisted of proliferative diabetic retinopathy (48 eyes), complex retinal detachment (33 eyes), proliferative vitreoretinpathy (11 eyes) and ocular trauma (10 eyes). Analysed variables were preoperative visual acuity, rubeosis iridis, nuber of operations, duration of tamponade, emulsification of silicone oil, lentile status, anterior proliferative vitreoretinpathy, keratopathy, change of ocular tension, redetachment, macular degeneration and electroretinogram. RESULTS: Anatomic success was achieved in 95 of 102 eyes (93.1%) and functional success was achieved in 66 eyes (64.7%). Change of ocular tension over 10mmHg, anterior proliferative vitreoretinpathy and anatomical failure were statistically significant prognostic factors. CONCLUSIONS: Silicone oil endotamponade is an effective measure for complex retinal diseases, but its complication has always been an issue. If these complications can well be kept under the control, silicone oil endotamponade will become more widely used surgical modality.

Expression of Vascular Endothelial Growth Factor after Laser Induced Retinal Vein Occlusion in the Rat Eye

PURPOSE: To examine the effects of retinal vein occlusion (RVO) on VEGF expression and the ultrastructural change of the various ocular tissues in the rat. METHODS: Sprauge Dawley rats were grouped into RVO group induced with argon laser (n=30) and control (n=10). The ocular tissues of the rats were collected on the first, third and seventh day after RVO. VEGF expression was evaluated with immunohistochemical stain, and the ultrastructural changes were observed with electron microscopy. RESULTS: In control group, VEGF stain was positive in various ocular tissues except outer nuclear cells. In RVO group, VEGF expression had gradual increase in the inner nuclear layer, the retinal pigment epithelia and the ciliary body epithelia after RVO. Especially, in the retinal pigment epithelia, VEGF was significantly increased on the seventh day. In electron microscopic examination, degenerative changes had gradual increase in the inner and middle retinal layers after RVO. The degenerative changes in the retinal pigment epithelia were noted on the third day, and in the retinal photoreceptor cells on the seventh day. CONCLUSIONS: These results showed that VEGF expressions in the inner nuclear layer, retinal pigment epithelia and ciliary body epithelia had a gradual increase, and the ischemic damages of the retina and the optic nerve progressed from the inner layer to the outer layer after RVO.

Vitreous Vascular Endothelial Growth Factor Concentration In Various Vitreoretinal Disorders

PURPOSE: Vascular endothelial growth factor (VEGF) has been identified as an endothelial cell-specific angiogenic factor of intraocular neovascularization, a pathologic complication of many vitreoretinal disorders. We studied to evaluate clinical correlation of intravitreal VEGF concentration and various vitreoretinal disorders. METHODS: Forty eight vitreous fluid samples were obtained at the time of vitreoretinal surgery from 43 patients of various disorders. Concentrations of VEGF1 6 5 in vitreous fluid were determined by Human VEGF ELISA kit and its correlation with diabetes, intraocular hemorrhage, neovascularization, proliferative vitreoretinopathy, retinal detachment, pan retinal photocoagulation, and postoperative condition was statistically analyzed. RESULTS: Intravitreal concentrations of VEGF in case of intraocular hemorrhage (0.809+/-1.467 ng/ml), neovascularization (1.167+/-1.656 ng/ml), and anterior segment neovascularization (2.381+/-2.043 ng/ml) were significantly high (P<0.05). CONCLUSIONS: VEGF plays a major role in the development of neovascularization in the various retinal disorders.

The Influences of Arteriosclerosis on the Development and Progression of Diabetic Retinopathy

To evaluate the relationship between arteriolosclerosis and diabetic retinopathy, we graded the levels of diabetic retinopathy and arteriolosclerosis and compared each other in 255 patients with non-insulin dependent diabetes. And we also measured serum lipid levels and checked other risk fac-tors for diabetic retinopathy. SPSS was used for statistical analysis. Patients with advanced arteriolosclerosis were at higher risk of severe diabetic retinopathy. And patients with elevated plasma total cholesterol, LDL-C, TG had more severe levels of diabetic retinopathy than whose lipid levels were normal. These results suggested that advanced arteriolosclerosis and elevated serum lipid levels are associated with severe diabetic retinopathy. For preventing visual threatening complications of diabetic retinopathy, the degree of arteriolosclerosis and serum lipid levels should be carefully monitored in the evaluation of diabetic retinopathy.

Characteristics of Tear Lipid Layer on Tears copy in Dry Eye Symptom and Non-Dry Eye Symptom Group

The lipid layer plays a important role in tear film stability. And several studies have reported the differences of lipid layer pattern and tear film break up time between normal and dry eye. To determine the availability of Tearscope(Keeler, UK), we observed the characteristics of lipid layer and compared non-invasive break up time(NIBUT) to invasive break up time(IBUT) in dry eye symptom and non-dry eye symptom group. By questionnaire, we selected the dry eye symptom(94 eyes in 47 persons) and the non-dry eye symptom(112 eyes in 56 persons) group. We observed lipid layer pattern and color by Tearscope, and measured NIBUT of Tearscope and IBUT of fluorescein solution. In the lipid layer, the dry eye symptom group had brown-yellow(about 112 nm) and uneven pattern. But, the non-dry eye symptom group represented amorphous(about 94 nm) and even pattern. In NIBUT, the dry eye symptom group had 9.57+/-11.40sec and the non-dry eye symptom group represented 27.42+/-20.15sec. In IBUT, two groups had 6.38+/-4.45sec and and 13.02+/-8.41sec, respectively. In conclusion, Tearscope is available in diagnosis and treatment in dry eye and also in diagnosis of tear lipid layer disorder.

The Effects of Calcium Dobesilate(Doxium) on the Electroretinogram in Patients with Diabetic Retinopathy

The purpose of the study is to evaluate the effects of calcium dobesilate (Doxium) on the electroretinographic changes in 60 non-insulin dependent diabetic patients with mild to moderate diabetic retinopathy, randomly assigned to receive either oral calcium dobesilate l000mg twice 8 day for 6 months or without medication. And also the effects of blood HbAlc and retinal photocoaglulation on the electroretinographic changes were evaluated. All patients were tested electroretinography with UTAS-2000 (LKC co., USA) before treatment and six months later respectively. The time interval changes of the electroretinogram were analyzed with student t-test program. As a result, no interval changes of the electroretinographic b-wave amplitudes and b/a ratio were noted in both groups, but the oscillatory potentials were significantly decreased after 6 months in the non-treated group (p:0.002). As compared to calcium dobesilate treated group, the non-treated group with blood HbAlc over 6.5mg% (p:0.008) or treated with retinal photocoagulation (p:0.001) showed a significant decrease of the oscillatory potentials. In conclusion, the administration of calcium dobesilate in the patients with diabetic retinopathy prevents an oscillatory potentials reduction, especially in patients with blood level of HbAlc below 6. 5mg% or treated with retinal photocoagulation.

A Case of Crystalline Retinopathy

Crystalline retinopathy is a tapetoretinal degeneration characterized by glistening yellow intraretinal crystals in the posterior pole, chorioidal sclerosis, and corneal crystalline dystrophy. We have recently encountered a 36 year-old female patient with bilateral intraretinal crystalline depositions who presented with a complaint of visual disturbance in her right eye for the last six months. Typical fundus findings of crystalline deposition in the posterior pole, tapetoretinal dysfunctions in the electrophysiologic tests and choriocapillaris filling defects in the fluorescein angiogram suggest that this the disorder is a widespread choriocapillaris and tapetoretinal disorder. There are no significant abnormal findings in serologic and radiologic examinations.

The Changes of the Visual Evoked Potentials and Visual Acuity after Silicone Oil Removal in the Vitrectomized Eyes

To know the effect of the intravitreal silicone oil affecting the visual evoked potentials (VEPs), we reviewed 19 patient's charts retrospectively. All patients had received pars plana vitrectomies with intravitreal silicone oil injection. The oil was removed after a few months of intravitreal silicone oil. The eyes showing operative or postoperative complication were excluded in this study. The VEPs and visual acuity were tested one day before and two weeks after intravitreal silicone oil removal. The changes of VEPs and visual acuities between the pre- and post-silicone oil removal were analized. And the changes of VEPs according to the changes of the visual acuities in the pre- and post-silicone oil removal were analized with student t-Test and Spearman corelation. The VEPs amplitudes decreased significantly (p=0.03) after silicone oil removal, and the latencies increased slightly but statistically not significant. The findings suggested that intravitreal surgery itself may influence the VEPs. After removal of intravitreal silicone oil, no significant relationship was found between the changes of VEPs and those of visual acuities.

Prevalence and Risk Factors of Diabetic Retinopathy: In First Fundus Examined Diabetic Patients

We performed a epidemiologic study to find a prevalence and risk factors of diabetic retinopathy. We reviewed 130 diabetic patients who had been performed the fundus examination for the first time for retinopathy at the ophthalmic department of Chung Ang university hospital from March 1993 to December 1993. We studied epidemiologic work-up sheet and performed ophthalmic and laboratory examination. The patients' ages ranged from 25 to 81 years, with an average age of 58.9 years. The age, sex, intraocular pressure, fasting blood sugar, post cibos 2 hours (Pc2hrs), age of onset, residence, smoking, alcohol drinking, diet pattern, blood type, treatment method and menstruation status were not significantly correlated with prevalence of diabetic retinopathy statistically(p>0.05). But the duration of diabetes(p<0.01), glycosylated hemoglobin(HbA1C) and cataract operation(p<0.05) were significantly correlated with diabetic retinopathy statisically. The prevalence of diabetic retinopathy was 28.5%(background changes in 21.5%, preproliferative changes in 4.6% and proliferative change in 2.4%). The mean interval between diagnosis of diabetes and the first examination of retinopathy was 6.62 years.