Advanced age-related macular degeneration and risk factors in eyes with pachydrusen

The risk of progression to advanced age-related macular degeneration (AMD) varies depending on the type of drusen. This retrospective longitudinal study included 248 eyes of 156 patients with pachydrusen without advanced AMD at baseline. Macular neovascularization (MNV) and geographic atrophy (GA) were evaluated. Risk factors for progression to advanced AMD were determined using multivariate Cox regression analysis. The mean age at baseline was 65.4 ± 9.1 years, and the mean follow-up duration was 6.40 ± 3.58 years. The mean total number of pachydrusen and macular pachydrusen were 4.10 ± 2.85 and 2.27 ± 1.81 per eye, respectively. Pachydrusen was accompanied by other types of drusen in 4.8% (12 eyes) of eyes at baseline. During follow-up, MNVs occurred in 2.8% (seven eyes), including polypoidal choroidal vasculopathy (PCV six eyes); however, no GA occurred. Regarding risk factors for progression to neovascular AMD, age (p = 0.023) and macular pigmentary changes (p = 0.014) were significantly associated with MNV development. The cumulative incidence of MNV was significantly higher in the group with macular pigmentary changes (17.39% vs. 0.57% at 10 years; p = 0.0005). The number of macular pachydrusen and the presence of MNV in the fellow eye did not show a statistically significant relationship with MNV development. Age and macular pigmentary changes are risk factors for MNV development in the eyes with pachydrusen. Eyes with pachydrusen appear to have a risk profile for advanced AMD that is different from that of AMD eyes with drusen or drusenoid deposits other than pachydrusen.

Macular lesions associated with age-related macular degeneration in pachydrusen eyes

BACKGROUND

To investigate the prevalence of macular lesions associated with age-related macular degeneration (AMD) in eyes with pachydrusen.

METHODS

Clinical records and multimodal imaging data of patients over 50 years old with drusen or drusenoid deposits were retrospectively assessed, and eyes with pachydrusen were included in this study. The presence of AMD features, including drusen or drusenoid deposits, macular pigmentary abnormalities, geographic atrophy (GA), and macular neovascularization (MNV), were evaluated.

RESULTS

Out of 967 eyes of 494 patients with drusen or drusenoid deposits, 330 eyes of 183 patients had pachydrusen (34.1%). The mean age was 66.1 ± 9.3 years, and the subfoveal choroidal thickness (SFCT) was 292.7 ± 100.1 μm. The mean number of pachydrusen per eye was 2.22 ± 1.73. The majority of eyes with pachydrusen had no other drusen or drusenoid deposits (95.2%). Only 16 eyes (4.8%) had other deposits, including soft drusen (10 eyes, 3.0%), cuticular drusen (3 eyes, 0.9%), and reticular pseudodrusen (RPD; 3 eyes, 0.9%). Macular pigmentary abnormalities accompanied pachydrusen in 68 eyes (27.4%). None of the eyes had GA, and 82 eyes (24.8%) had MNV. The majority of MNV was polypoidal choroidal vasculopathy (PCV; 65 eyes, 19.7%), followed by type 1 (10 eyes, 3.0%), type 2 (5 eyes, 1.5%), and type 3 MNV (2 eyes, 0.6%).

CONCLUSIONS

Eyes with pachydrusen in Korean population have several characteristic AMD lesions in low frequencies. These findings indicate that pachydrusen might have diagnostic and prognostic values that are different from those of other drusen or drusenoid deposits.

The risk of fracture in age-related macular degeneration according to the presence of visual disability: a nationwide cohort study

PURPOSE

To evaluate the association between age-related macular degeneration (AMD) with or without visual disability (VD) and the risk of fracture using the National Health Insurance data in South Korea.

METHODS

In total, 3,894,702 individuals who had taken part in health-screening programs between January 1, 2009, and December 31, 2009, were included in the cohort and followed until December 31, 2019. The participants with VD, which could be related to the severity of AMD, were defined as those with a loss of vision or visual field defect as certified by the Korean government's Ministry of Health and Welfare. The hazard ratio was calculated for groups (control and AMD with/without VD) using the multivariable-adjusted cox regression analysis.

RESULTS

In total, 466,890 participants (11.99%) were diagnosed with fractures during the study period. An increased risk of fracture was observed in individuals with AMD compared with the control (adjusted hazard ratio (aHR), 1.09, 95% confidence interval (CI), 1.06-1.11). Furthermore, among the AMD individuals, an increased risk of fracture was prominent in individuals with VD (aHR 1.17, 95% CI 1.08-1.27) than those without VD (aHR 1.08, 95% CI 1.06-1.11) compared with the reference group (control).

CONCLUSIONS

AMD was associated with an increased risk of fracture even without VD. Prevention for fracture should be considered in AMD patients, especially when accompanied by VD.

Enhancing foveal avascular zone analysis for Alzheimer's diagnosis with AI segmentation and machine learning using multiple radiomic features

We propose a hybrid technique that employs artificial intelligence (AI)-based segmentation and machine learning classification using multiple features extracted from the foveal avascular zone (FAZ)-a retinal biomarker for Alzheimer's disease-to improve the disease diagnostic performance. Imaging data of optical coherence tomography angiography from 37 patients with Alzheimer's disease and 48 healthy controls were investigated. The presence or absence of brain amyloids was confirmed using amyloid positron emission tomography. In the superficial capillary plexus of the angiography scans, the FAZ was automatically segmented using an AI method to extract multiple biomarkers (area, solidity, compactness, roundness, and eccentricity), which were paired with clinical data (age and sex) as common correction variables. We used a light-gradient boosting machine (a light-gradient boosting machine is a machine learning algorithm based on trees utilizing gradient boosting) to diagnose Alzheimer's disease by integrating the corresponding multiple radiomic biomarkers. Fivefold cross-validation was applied for analysis, and the diagnostic performance for Alzheimer's disease was determined by the area under the curve. The proposed hybrid technique achieved an area under the curve of [Formula: see text]%, outperforming the existing single-feature (area) criteria by over 13%. Furthermore, in the holdout test set, the proposed technique exhibited a 14% improvement compared to single features, achieving an area under the curve of 72.0± 4.8%. Based on these facts, we have demonstrated the effectiveness of our technology in achieving significant performance improvements in FAZ-based Alzheimer's diagnosis research through the use of multiple radiomic biomarkers (area, solidity, compactness, roundness, and eccentricity).

Increased risk of Parkinson's disease amongst patients with age-related macular degeneration and visual disability: A nationwide cohort study

BACKGROUND AND PURPOSE

The association between Parkinson's disease (PD) and age-related macular degeneration (AMD) has been shown in previous reports. However, the association between the severity of AMD and PD development is unknown. The aim was to evaluate the association of AMD with/without visual disability (VD) with the risk of PD occurrence using the National Health Insurance data in South Korea.

METHODS

A total of 4,205,520 individuals, 50 years or older and without a previous diagnosis of PD, participated in the Korean National Health Screening Program in 2009. AMD was verified using diagnostic codes, and participants with VD were defined as those with loss of vision or visual field defect as certified by the Korean Government. The participants were followed up until 31 December 2019, and incident cases of PD were identified using registered diagnostic codes. The hazard ratio was calculated for groups (control and AMD with/without VD) using multivariable adjusted Cox regression analysis.

RESULTS

In total, 37,507 participants (0.89%) were diagnosed with PD. Amongst individuals with AMD, the risk of PD development was higher in individuals with VD (adjusted hazard ratio [aHR] 1.35, 95% confidence interval [CI] 1.09-1.67) than in those without (aHR 1.22, 95% CI 1.15-1.30) compared with controls. Additionally, an increased risk of PD was observed in individuals with AMD compared with controls, regardless of the presence of VD (aHR 1.23, 95% CI 1.16-1.31).

CONCLUSIONS

Visual disability in AMD was associated with the development of PD. This suggests that neurodegeneration in PD and AMD may have common pathways.

Microperimetric evaluation for different methods of epiretinal membrane surgery

PURPOSE

To investigate the anatomic and functional outcomes using microperimetry for the surgical methods for idiopathic epiretinal membranes (ERM).

METHODS

This retrospective study included 41 eyes from 41 patients. All patients underwent combined epiretinal membrane and cataract surgery. Best-corrected visual acuity (BCVA), optical coherence tomography, and microperimetry were performed before and 6 months and 1 year after surgery. The patients were divided into 3 groups; "ERM removal only without indocyanine green (ICG) staining", "ERM and internal limiting membrane (ILM) removal without ICG staining", and "ERM and ILM removal with ICG staining".

RESULTS

Preoperatively, the ages, BCVAs, central macular thickness (CMT), and mean retinal sensitivities of central 6° (MRSs) of the groups were not significantly different (p > 0.05). Postoperatively, the MRSs of the "ERM removal only without ICG staining" and "ERM and ILM removal without ICG staining" groups were not significantly different (p > 0.05). The MRSs of the "ERM and ILM removal without ICG staining" and "ERM and ILM removal with ICG staining" groups were not significantly different (p > 0.05). However, the MRSs of the "ERM and ILM removal with ICG staining" group significantly reduced than "ERM removal only without ICG staining" group (p < 0.05).

CONCLUSION

This retrospective study found reduced retinal sensitivity in ERM and ILM removal with ICG staining group compared to ERM removal only without ICG staining. Further studies with larger sample sizes are required.

Response to brolucizumab treatment for refractory serous pigment epithelial detachment secondary to polypoidal choroidal vasculopathy

PURPOSE

To report the efficacy and safety of brolucizumab in the treatment of refractory serous pigment epithelial detachment (PED) secondary to polypoidal choroidal vasculopathy (PCV).

METHODS

Twenty-six eyes of 26 patients were included. Intravitreal brolucizumab 6.0 mg was administered, followed by pro re nata (PRN) retreatment at monthly follow-ups. All patients underwent spectralis domain optical coherence tomography (SD-OCT), fluorescein angiography, and indocyanine green angiography before the first brolucizumab injection. SD-OCT was repeated at follow-up visits. The height and width of the serous PEDs, measured using SD-OCT, were analyzed.

RESULTS

The number of previous anti-VEGF injections was 12.3 ± 15.0. During brolucizumab treatment, anatomical improvement was achieved and maintained in the height and width of the PEDs (p < 0.05). However, the visual outcome did not improve significantly (p > 0.05). A good response was achieved in 69.2% of eyes at 1 month and at the last visit. Relapse and complete resolution were observed in 27.8 and 23.1% of patients, respectively. The number of brolucizumab injections was 2.00 ± 0.85. Intraocular inflammation, vascular obstruction, and retinal pigment epithelial tears were not observed.

CONCLUSION

Intravitreal brolucizumab may be an effective and safe treatment option for refractory serous PEDs in patients with PCV.

Age-related macular degeneration eyes presenting with cuticular drusen and reticular pseudodrusen

This study aimed to describe the clinical characteristics of age-related macular degeneration (AMD) eyes with both cuticular drusen (CD) and reticular pseudodrusen (RPD). Clinical records of patients diagnosed with CD or RPD with multimodal imaging was reviewed for patients diagnosed with both CD and RPD. The distribution patterns of CD (macular and diffuse type) and RPD (localized, intermediate, and diffuse type), presence of soft drusen, large drusen (> 200 µm), variant subretinal drusenoid deposits, and macular complications were investigated. Of the 220 eyes of 110 patients diagnosed with CD and 926 eyes of 463 patients diagnosed with RPD, 13 eyes of seven patients met the diagnostic criteria for both CD and RPD. The mean age at initial presentation was 71.4 ± 8.8 years and six patients were female. The mean subfoveal choroidal thickness was 143.8 ± 25.1 µm. The distribution of CD was of the macular type in all eyes. Distribution of RPD was localized in 11 eyes (84.6%) and intermediate in two eyes (15.4%). Soft drusen, large drusen, and variant subretinal drusenoid deposits were present in 13 (100%), 12 (92.3%) and, seven (53.8%) eyes, respectively. Macular neovascularization was observed in two eyes (15.4%). CD and RPD can coexist in eyes with AMD. Multimodal imaging should be used for AMD eyes with features suggestive of CD and RPD, considering the high likelihood of developing late AMD.

Genetic Influence on Choroidal Volume

PURPOSE

To evaluate the degree of genetic influence on macular choroidal volume.

DESIGN

A cross-sectional twin and family study.

METHODS

In total, 353 Korean adults with healthy eyes from 78 households with 2 or more family members were included in the study. Macular choroidal volume was measured using spectral-domain optical coherence tomography with enhanced depth imaging at 9 macular subfields defined by the ETDRS. Demographics and clinical characteristics were investigated, including age, sex, axial length, hypertension, diabetes, drinking habits, and smoking status. The associations of these factors with macular choroidal volume were assessed using univariate and subsequent multivariate regression analyses while accounting for family structure. The heritability estimates of macular choroidal volume in total and at each of the 9 macular subfields were calculated after adjusting the covariates.

RESULTS

Patients who were younger, male, and had a shorter axial length showed associations with greater choroidal volume (P < .001 for all 3 independent variables). The covariates-adjusted heritability (±standard error) of the total macular choroidal volume was 0.76 ± 0.06, and the heritabilities of choroidal volume at each subfield ranged from 0.55 ± 0.09 (inner temporal subfield) to 0.77 ± 0.08 (inner superior subfield).

CONCLUSION

The macular choroidal volume is highly heritable.

Differential Effect of the Metabolic Syndrome on the Incidence of Retinal Vein Occlusion in the Korean Population: A Nationwide Cohort Study

Purpose

To investigate the impact of the metabolic syndrome (METS) on the incidence of retinal vein occlusion (RVO).

Methods

This is a retrospective cohort study using Korean National Health Insurance System data. 23,153,600 subjects without previous history of RVO underwent a National Health Screening Program examination between 2009 and 2012. They were monitored for RVO development (registration of diagnostic code for RVO) until 2015. Presence of METS was defined using the data from the National Health Screening Program examination according to the revised criteria of the National Cholesterol Education Program Adult Treatment Panel III. A multivariate adjusted Cox regression analysis was used to reveal hazard ratios and 95% confidence interval for RVO development in the presence of METS.

Results

The age of the subjects was 47.64 ± 13.51 years. In this cohort, 11,747,439 (50.7%) were male, 11,406,161 (49.3%) were female, and 6,398,071 subjects (27.6%) were diagnosed with METS. The overall incidence of RVO was 0.947 per 1000 person-years. The adjusted hazard ratio of RVO in the presence of METS was 1.458 (95% confidence interval, 1.440–1.475; P < 0.001) after adjusting for age, sex, smoking status, alcohol consumption, physical activity, and income. Among all of the criteria for METS diagnosis, elevated blood pressure was the greatest risk for RVO development (adjusted hazard ratio, 1.610; 95% confidence interval, 1.589–1.631; P < 0.001).

Conclusions

METS and each of diagnostic criteria was associated with an increased risk of RVO development. Elevated blood pressure seems to be especially important factors for RVO development.

Translational Relevance

Our results provide information about the link between METS and RVO.

Heritability of macular ganglion cell inner plexiform layer thickness as determined by optical coherence tomography: the Healthy Twin Study

PURPOSE

To evaluate genetic influence on macular ganglion cell inner plexiform layer (GCIPL) thickness.

METHODS

Macular GCIPL thickness was measured with optical coherence tomography in nine macular subfields defined by the E TDRS. Intraclass correlation coefficients (ICC) of GCIPL thickness by different types of family relationships were estimated to assess intrafamilial resemblance. Then, heritability of GCIPL thickness was estimated.

RESULTS

Three hundred and sixty-one Korean adults from 89 families with normal healthy eyes were included. GCIPL thickness was highest in inner subfields and lowest in fovea. Monozygotic twin pairs showed significantly higher ICCs of GCIPL thickness in all subfields compared to those in parent-offspring pairs and sibling pairs. GCIPL thickness was highly heritable in the centre (0.71) and outer subfields but moderate to highly heritable in inner subfields. Heritability of GCIPL thickness in outer subfields was 0.69, 0.67, 0.72 and 0.68 for superior, inferior, temporal and nasal fields, respectively. Heritability of GCIPL thickness in inner subfields was 0.55, 0.56, 0.75 and 050 for superior, inferior, temporal and nasal subfields, respectively.

CONCLUSION

Macular GCIPL thickness is significantly influenced by genetic factors. It varies according to subfields with moderate to high heritability in all subfields.

Clinical manifestations of cuticular drusen in Korean patients

Cuticular drusen show some similarities to and differences from soft drusen in age-related macular degeneration (AMD) and might thus be a unique AMD subtype. Previous studies on cuticular drusen were performed mainly in white ethnic groups, but AMD shows ethnic differences. We investigated clinical manifestations of cuticular drusen in Korean patients to evaluate possible ethnic differences. Clinical records of Korean patients with cuticular drusen were retrospectively reviewed. Fundus distribution pattern, imaging features, and presence of large drusen, drusenoid pigment epithelial detachment (PED), and macular complications, including geographic atrophy (GA), choroidal neovascularization (CNV), and acquired vitelliform lesion (AVL), were assessed via multimodal imaging in 162 eyes with cuticular drusen (n = 81 patients; 67 females; mean age: 66.6 ± 9.1 years). Diffuse distribution was found in 61.7% and peripapillary involvement in 75.3% of eyes. Large drusen, drusenoid PED, GA, CNV, and AVL were observed in 59.3%, 26.5%, 18.5%, 3.7%, and 1.2% of eyes, respectively. The macular complication prevalence was similar between patients ≤ 60 and those > 60 years old. In Korean patients, cuticular drusen were less frequently associated with macular complications than in white patients, and the proportion of macular complications differed significantly, with AVL representing an uncommon complication.

Differential effect of obesity on the incidence of retinal vein occlusion with and without diabetes: a Korean nationwide cohort study

We aimed to evaluate the association between obesity and the incidence of retinal vein occlusion (RVO) with and without diabetes mellitus (DM).This is a retrospective cohort study using Korean National Health Insurance System data. The participants were 23,061,531 adults older than 20 years who received a health examination at least once between 2009 and 2012, and all patients were observed for RVO development until 2015. We used a multivariate adjusted Cox regression analysis to evaluate the association between RVO and body mass index (BMI) with and without DM. The analysis were evaluated via a hazard ratio (HR) and 95% confidence interval (CI). The age-, sex-, and multivariable-adjusted HRs for RVO were stratified by BMI. This population-based study revealed evidence that obesity has a different effect on the incidence of RVO in the presence and absence of DM.In people with DM, a lower BMI was associated with an increased risk of RVO, and a higher BMI was associated with a lower risk for RVO. In people without DM, the correlation was reversed: a lower BMI was associated with a lower risk for RVO and vice versa.

Genetic influence on macular retinal nerve fibre layer thickness according to retinal subfield

Background/aim

Characterising genetic effect on macular retinal nerve fibre layer (RNFL) is needed to obtain better understanding of various retinopathies and optic neuropathies. The purpose of this study was to evaluate genetic influence on macular RNFL thickness.

Methods

This is a cross-sectional, twin and family study. Three hundred and sixty-two Korean adults with healthy eyes were included in the study from 79 households with two or more family members. Macular RNFL thickness was measured with optical coherence tomography at nine macular subfields defined by the ETDRS. Intraclass correlation coefficients (ICCs) were estimated to assess intrafamilial resemblance of RNFL thickness by different types of family relationship. Heritability of RNFL thickness was evaluated using variance decomposition model.

Results

RNFL thickness increased from central subfield to outer subfields. Temporal quadrant RNFL was thinner compared with other quadrants. Monozygotic twin pairs showed the highest ICCs of RNFL thickness, although the ICC level varied across different subfields. Heritability of RNFL thickness was the highest at central subfield (0.81). RNFL thicknesses of outer subfields were moderately to highly heritable: 0.53, 0.71, 0.47 and 0.66 for superior, inferior, temporal and nasal fields, respectively. RNFL thicknesses at inner subfields showed the lowest heritability: 0.21, 0.24, 0.27 and 0.27 for superior, inferior, temporal and nasal subfields, respectively.

Conclusion

Macular RNFL thickness is significantly influenced by genetic factors. It varies largely by subfields with the highest heritability at the central subfield and a relatively lower heritability at inner subfields.

Retinal Vein Occlusion is Associated with Low Blood High-Density Lipoprotein Cholesterol: A Nationwide Cohort Study

PURPOSE

To investigate association between the development of retinal vein occlusion (RVO) and blood high-density lipoprotein cholesterol (HDL-C).

DESIGN

A retrospective, nationwide, population-based cohort study.

METHODS

This study was set in the Republic of Korea and included 23,149,403 people ≥20 years of age who underwent the Korean National Health Screening Program examination between January 2009 and December 2012. Among them, the RVO group was composed of patients with an initial diagnosis of RVO made between 2009 and 2015 (n = 117,639). The earliest claim with an RVO diagnostic code was considered as the incident time. The predictive value of HDL-C level for RVO was analyzed using hazard ratios. The primary outcome measure was the incident cases of RVO.

RESULTS

Subjects with RVO were generally older; had high body mass index, waist circumference, fasting blood glucose, blood pressure, total and low-density lipoprotein cholesterol, and triglyceride values, and low glomerular filtration rate and HDL-C values; and were more likely to experience diabetes mellitus and hypertension compared with the non-RVO group. The fully adjusted hazard ratio of RVO was 1.12 (95% confidence interval 1.10-1.14) in the lowest quartile of HDL-C versus in the highest quartile. The association between the development of RVO and HDL-C was higher those with a younger age, male sex, current smoking habit, diabetes mellitus, and hypercholesterolemia. In addition, we observed a significant synergistic effect of low HDL-C level with obesity and hypertension.

CONCLUSION

This is the first nationwide population-based epidemiologic study evaluating the association between HDL-C level and the risk of RVO development. A significant association between low HDL-C and RVO development was found.

Measurable Range of Subfoveal Choroidal Thickness With Conventional Spectral Domain Optical Coherence Tomography

Purpose

We investigate the measurable range of subfoveal choroidal thickness (SFCT) with conventional spectral domain optical coherence tomography (SD-OCT) in normal healthy eyes.

Methods

All subjects underwent an SD-OCT horizontal line scan centered at the fovea with standard and enhanced depth imaging (EDI) techniques. Two independent observers manually measured SFCT on standard and EDI-OCT images, if two choroidal borders were identified. The rate of successful measurement with standard OCT was evaluated. Inter- and intraclass correlation coefficients and Bland-Altman plots were used for analysis.

Results

OCT images of 724 normal healthy eyes from 374 subjects were evaluated. Although the inner choroidal border was identified on all OCT images, the outer choroidal border was identified on 378 of 724 (52.2%) conventional OCT images. Mean SFCT of all study eyes measured by EDI-OCT images was 292.6 ± 94.0. The number of successful measurements with conventional OCT was 100%, 87.5%, 48.1%, 33.0%, and 0%, in the SFCT ranges of <241, 241-280, 281-320, 321-360, and >360 μm, respectively. The accumulated rate of successful measurement with conventional OCT was 100%, 96.4%, and 82.2% in the SFCT ranges of ≤240, ≤280, and ≤320 μm, respectively. Two protocols showed good inter-correlation of SFCT, when SFCT were measurable in both scans.

Conclusions

SFCT can be measured by conventional OCT in eyes with thin choroid, and the measured value shows high agreement with those measured by EDI-OCT. In such eyes, conventional OCT can be used potentially to evaluate the retina and choroid.

Translational Relevance

In eyes with a thin choroid, conventional OCT can be used potentially to evaluate the retina and choroid with high agreement with EDI-OCT.

Ultra-wide-field angiography findings in acute Vogt-Koyanagi-Harada disease

BACKGROUND/AIMS

To investigate the prevalence of abnormal central and peripheral ultra-wide-field (UWF) angiography findings, and their association with clinical features in acute Vogt-Koyanagi-Harada (VKH) disease.

METHODS

This retrospective, observational study included 26 eyes of 13 treatment-naïve patients with acute VKH disease who underwent UWF fluorescein angiography (FA). Sixteen eyes of eight patients also underwent UWF indocyanine green angiography (ICGA). A circle simulating the central 75° field was used to divide the acquired image into the central fundus area (CFA) and peripheral fundus area (PFA), in which the presence of six previously reported abnormal angiographic findings were analysed. Correlations between abnormal angiography findings in FA and clinical features were also investigated.

RESULTS

All eyes demonstrated more than one abnormal angiographic finding in both the CFA and PFA. UWF FA revealed three abnormal findings in the CFA versus the PFA: focal leakage (92.3% vs 76.9%); pooling with a dark rim (84.6% vs 53.8%); and retinal vascular leakage (0% vs 46.2%). UWF ICGA revealed three abnormal findings in the CFA versus the PFA: hypofluorescent dark dots (100% vs 100%); diffusely leaking fuzzy choroidal vessels (93.8% vs 75.0%); and late hypofluorescent patches (81.3% vs 31.3%). Pooling with a dark rim and retinal vascular leakage in the PFA were significantly associated with low initial visual acuity (p=0.03) and subfoveal choroidal thickness change ratio (p=0.04), respectively.

CONCLUSION

Abnormal UWF angiography findings were frequently detected in the CFA and PFA. Such findings may be useful in evaluation and monitoring of VKH disease.

Comparison of clinical features and 3-month treatment response among three different choroidal thickness groups in polypoidal choroidal vasculopathy

Eyes with polypoidal choroidal vasculopathy (PCV) were recently reported to have various choroidal thickness, and choroidal thickness might be associated with visual outcome in the treatment of many retinal disorders. The range of subfoveal choroidal thickness (SFCT), clinical features, and 3-month treatment response among three groups having different range of SFCT were investigated in PCV eyes. In 78 treatment-naïve eyes with PCV, SFCT was measured using optical coherence tomography. Eyes were classified into thin, medium, and thick groups, using mean and one standard deviation of SFCT. Clinical features and imaging findings were compared among the three groups. Some eyes were treated with three consecutive monthly injection of anti-vascular endothelial growth factor (VEGF) as an initial treatment. They were also classified into three thickness groups, and the short-term post-treatment improvement in visual acuity and central retinal thickness were compared among groups. The mean SFCT was 271.9 ± 135.6 μm. Twelve, 53, and 13 eyes were classified into thin (<136.3 μm), medium (136.3–407.5 μm), and thick (>407.5 μm) groups, respectively. The thin group showed older age, lower visual acuity, and a higher prevalence of fundus tessellation than the other two groups (P <0.05). In multiple linear regression analyses, baseline BCVA was correlated with baseline SFCT. Forty-six eyes completed three consecutive anti-VEGF treatments. The thin group showed no visual improvement after treatment (P = 0.141), unlike the other two groups showing visual improvement (P<0.05). Eyes with PCV have a broad range of SFCT, and PCV eyes with a thin choroid manifest worse visual function than eyes with a medium or thick choroid.

Incidence and prevalence of uveitis in South Korea: a nationwide cohort study

AIM

To evaluate the incidence and prevalence of uveitis and associated risk factors in South Korea.

METHODS

For this retrospective national cohort study, approximately 1 000 000 Korean residents were randomly selected from the Korean National Health Insurance Service database. Uveitis was defined according to the Korean Classification of Diseases. The uveitis incidence and prevalence were calculated. Sociodemographic factors and comorbidities associated with uveitis were evaluated via Cox proportional regression models.

RESULTS

A total of 1 094 440 subjects were evaluated over 7 051 346 person-years (mean follow-up: 6.44 years). Overall, 7447 newly developed uveitis cases were identified during the period of 2007-2013; the average incidence of uveitis was 10.6 per 10 000 person-years (95% CI 10.3 to 10.8). The average incidences of anterior and non-anterior uveitis were 9.0 and 1.5 per 10 000 person-years, respectively. The prevalence rates of uveitis, anterior uveitis and non-anterior uveitis were 17.3, 15.0 and 2.3 per 10 000 persons, respectively, during the period of 2007-2013. Increasing age, male sex, residing in a relatively rural area and high income were associated with uveitis, along with Behçet's disease, juvenile idiopathic arthritis, ankylosing spondylitis, systemic lupus erythematous, ulcerative colitis and tuberculosis.

CONCLUSIONS

The overall incidence of uveitis in Korea was similar to those reported in Taiwan and the USA. Despite a potentially inaccurate disease definition, claims data may be useful for monitoring the substantial uveitis burden in South Korea.

Error rate of automated choroidal segmentation using swept-source optical coherence tomography

PURPOSE

To investigate the error rate of automated choroidal segmentation and the effect of frame averaging on error rate.

METHODS

A horizontal B scan at the fovea was performed in patients having various retinochoroidal disorders using swept-source optical coherence tomography (OCT) with frame-averaging technique. Scanned images were classified into four morphological groups: normal from fellow eyes (NF ), normal from pathologic eyes (NP ), retinal abnormality (R) and retinochoroidal abnormality (RC) group. Choroidal segmentation was automatically performed using built-in software of a swept-source OCT device, and the error rate of choroidal segmentation was analysed.

RESULTS

Qualified images for all four averaging types with different number of averaged frames were acquired in 89 eyes of 77 patients. Images of 12, 20, 24 and 33 eyes were classified as NF , NP , R and RC group, respectively. The choroidal segmentation error was detected in 1-2 images (8.3-16.7%) in the NF group, 3-6 images (15.0-30.0%) in the NP group, 4-8 images (16.7-33.3%) in the R group and 17-19 images (51.5-57.6%) in the RC group. The error rate was significantly higher in RC group than other groups (p < 0.05). Increasing the number of frames for averaging showed no significant effect on the error rate in all groups (p > 0.05).

CONCLUSION

Automated choroidal segmentation showed a high error rate in images with choroidal abnormalities, and the averaging effect could not reduce the error rate significantly. Thus, further technological improvement is needed to increase the accuracy of the automated choroidal segmentation.

Retinal thickness and volume measured with enhanced depth imaging optical coherence tomography

PURPOSE

To evaluate the retinal thickness and volume measured with the enhanced depth imaging (EDI) method compared with those measured with the conventional method using spectral-domain optical coherence tomography (OCT).

DESIGN

Retrospective, observational, case-control study.

METHODS

Clinical records of 20 healthy subjects and those of 35 patients with chorioretinopathy (central serous chorioretinopathy, polypoidal choroidal vasculopathy, Vogt-Koyanagi-Harada disease, and reticular pseudodrusen) were analyzed retrospectively. All subjects underwent spectral-domain OCT using both the conventional and the EDI OCT raster scan protocols. The raster scan was composed of 31 B-scans that were 9.0 mm in length and 240 μm apart. Retinal thickness and volume of 9 Early Treatment Diabetic Retinopathy Study subfields were investigated. Intraclass correlation coefficients, Bland-Altman plots, and Wilcoxon signed-rank test results were used for the analysis.

RESULTS

Sixty-five eyes of 35 patients with chorioretinal diseases and 40 eyes of 20 normal healthy subjects were evaluated. The automatically measured retinal thickness and volume of 9 Early Treatment Diabetic Retinopathy Study subfields with conventional and EDI raster scan showed an intraclass correlation coefficient of 0.861 to 0.995 and 0.873 to 0.995, respectively. The 95% limits of agreement between the 2 protocols in the measurement of central subfield were -14.52 to 12.88 μm in retinal thickness and -0.014 to 0.013 mm³ in retinal volume. The differences of segmentation error rate between the 2 protocols were statistically insignificant (P > .05), except in eyes with reticular pseudodrusen in the subgroup analysis (P = .006). No significant differences were observed in measured values between healthy eyes and unaffected fellow eyes.

CONCLUSIONS

The EDI OCT raster scan showed high agreement with conventional OCT in the measurement of retinal thickness and volume and could be used to evaluate both the retina and choroid in normal eyes and in eyes with some forms of chorioretinal disorder.

Ultrawide-field fluorescein angiography for evaluation of diabetic retinopathy

Purpose

To investigate the advantages of ultrawide-field fluorescein angiography (FA) over the standard fundus examination in the evaluation of diabetic retinopathy (DR).

Methods

Ultrawide-field FAs were obtained in 118 eyes of 59 diabetic patients; 11 eyes with no DR, 71 eyes with nonproliferative diabetic retinopathy (NPDR), and 36 eyes with proliferative diabetic retinopathy (PDR), diagnosed by the standard method. The presence of peripheral abnormal lesions beyond the standard seven fields was examined.

Results

Ultrawide-field FA images demonstrated peripheral microaneurysms in six (54.5%) of 11 eyes with no DR and all eyes with moderate to severe NPDR and PDR. Peripheral retinal neovascularizations were detected in three (4.2%) of 71 eyes with NPDR and in 13 (36.1%) of 36 eyes with PDR. Peripheral vascular nonperfusion and vascular leakage were found in two-thirds of eyes with severe NPDR and PDR.

Conclusions

Ultrawide-field FA demonstrates peripheral lesions beyond standard fields, which can allow early detection and a close evaluation of DR.

Clinical features of reticular pseudodrusen according to the fundus distribution

BACKGROUND

To evaluate the morphological features and prevalence of accompanying late age-related macular degeneration (AMD) according to the fundus distribution of reticular pseudodrusen (RPD).

METHODS

According to the involved area in the fundus, the distribution of RPD was classified as localised, intermediate, or diffuse type. Morphology of RPD was classified as discrete, branching, or confluent pattern. The presence of late AMD was evaluated.

RESULTS

233 eyes of 121 patients with RPD were included. The distribution of RPD was localised, intermediate and diffuse type in 30.9%, 40.3% and 28.8% of eyes, respectively. The discrete, branching and confluent morphological patterns were found in 45.8%, 44.8% and 9.7% of the localised type, and in 0%, 13.8% and 86.2% of the intermediate type, respectively. In contrast, the diffuse type showed only the confluent morphological pattern. The prevalence of accompanying late AMD was 13.9%, 13.8% and 56.7% in the localised, intermediate and diffuse type, respectively, and it was significantly higher in the diffuse type (p<0.05).

CONCLUSION

RPD with diffuse distribution showed a confluent morphological pattern and a high prevalence of late AMD. RPD can be classified by the fundus distribution for the assessment of visual prognosis.

Epidemiologic characteristics of intraocular pressure in the Korean and Mongolian populations: the Healthy Twin and the GENDISCAN study

PURPOSE

The purpose of this study was to demonstrate a negative association between intraocular pressure (IOP) and age in 2 Asian populations. In addition, we evaluated genetic and nongenetic factors associated with IOP.

DESIGN

Family-based cohort study.

PARTICIPANTS

Study subjects >10 years of age from one Korean (The Healthy Twin; n = 1431) and 2 Mongolian populations (The GENDISCAN; n = 859 and 806) with IOP values.

METHODS

The IOP values were measured with a noncontact tonometer. Each participant received a standard health examination and received questionnaires, which include candidate risk factors on IOP. Mixed models were used to identify risk factors for IOP. Variance-component methods were applied to estimate the heritability of IOP.

MAIN OUTCOME MEASURES

The negative trend of IOP with aging and evaluation of impact of genetic and nongenetic components on IOP.

RESULTS

The mean ages were 43.6, 34.1, and 36.3 years for the Korean, Orhontuul, and Dashbalbar populations, respectively. The mean IOPs were 14.4 mmHg (95% confidence interval [CI], 14.3-14.6) in the Koreans and 14.1 mmHg (95% CI, 13.9-14.3) and 12.6 mmHg (95% CI, 12.4-12.9) in the Orhontuul and Dashbalbar populations, respectively. In the 3 populations, the IOP decreased as age increased. We replicated an association of systolic blood pressure (SBP) with IOP. In addition, components of the metabolic syndrome (MS), such as plasma glucose, lipid level, and body mass index, showed positive associations with IOP, after adjusting for age and SBP. The IOP also had strong genetic contributions in all populations (heritability, 0.47-0.51).

CONCLUSIONS

Negative associations between age and IOP were observed in all 3 populations, which cannot be explained by the increasing prevalence of myopia in the younger generation. The different age trend in IOP may in part be responsible for differences in the prevalence of glaucoma subtypes. Our findings suggest that associations between IOP and MS components were independent of established risk factors such as SBP or age. In addition, the importance of inherited risks requires further genetic dissection of IOP determinants for biological understandings of underlying pathophysiology.

Genetic influences on macular thickness in Koreans: the healthy twin study

PURPOSE

To estimate genetic influences accounting for macular thickness in the Korean population.

METHODS

Study subjects were 830 healthy Korean adults (117 monozygotic twin pairs and 523 family members) from the Healthy Twin study. Macular thickness was measured with optical coherence tomography for nine subfields including the fovea, four inner quadrants (within 1 to 3 mm of the center), and four outer quadrants (within 3 to 6 mm of the center). Quantitative genetic analyses were performed to estimate the heritability of macular thickness with respect to familial correlations.

RESULTS

Macular thickness varied by subfield and was thinnest at the fovea and thickest at the inner superior area. Heritability of macular thickness at each subfield was 0.76, 0.73, 0.70, 0.56, 0.67, 0.70, 0.73, 0.29, and 0.36 at the fovea, inner superior area, inner inferior area, inner nasal area, inner temporal area, outer superior area, outer inferior area, outer nasal area, and outer temporal area, respectively.

CONCLUSIONS

Genetic factors play a significant role in determining macular thickness in the Korean population.

Invariant NKT cells regulate experimental autoimmune uveitis through inhibition of Th17 differentiation

Although NKT cells have been implicated in diverse immunomodulatory responses, the effector mechanisms underlying the NKT cell-mediated regulation of pathogenic T helper cells are not well understood. Here, we show that invariant NKT cells inhibited the differentiation of CD4(+) T cells into Th17 cells both in vitro and in vivo. The number of IL-17-producing CD4(+) T cells was reduced following co-culture with purified NK1.1(+) TCR(+) cells from WT, but not from CD1d(-/-) or Jα18(-/-) , mice. Co-cultured NKT cells from either cytokine-deficient (IL-4(-/-) , IL-10(-/-) , or IFN-γ(-/-) ) or WT mice efficiently inhibited Th17 differentiation. The contact-dependent mechanisms of NKT cell-mediated regulation of Th17 differentiation were confirmed using transwell co-culture experiments. On the contrary, the suppression of Th1 differentiation was dependent on IL-4 derived from the NKT cells. The in vivo regulatory capacity of NKT cells on Th17 cells was confirmed using an experimental autoimmune uveitis model induced with human IRBP(1-20) (IRBP, interphotoreceptor retinoid-binding protein) peptide. NKT cell-deficient mice (CD1d(-/-) or Jα18(-/-) ) demonstrated an increased disease severity, which was reversed by the transfer of WT or cytokine-deficient (IL-4(-/-) , IL-10(-/-) , or IFN-γ(-/-) ) NKT cells. Our results indicate that invariant NKT cells inhibited autoimmune uveitis predominantly through the cytokine-independent inhibition of Th17 differentiation.

Clinical features and prognosis of HLA-B27 positive and negative anterior uveitis in a Korean population

Clinical features and prognosis of HLA-B27 positive anterior uveitis (AU) were assessed compared with HLA-B27 negative AU in a Korean population, based on the medical records of AU patients seen at a university hospital. Twenty-seven HLA-B27 negative, idiopathic AU patients (group I) and 55 HLA-B27 positive AU patients (group II) were studied. HLA-B27 positive group was further divided into 29 with associated systemic disease (seronegative spondyloarthropathy) (group IIA) and 26 without associated systemic disease (group IIB). Significantly more severe anterior chamber inflammation in terms of anterior chamber cells (P=0.006) and hypopyon formation (P=0.034) was observed with higher frequency of AU attacks (P=0.007) in the HLA-B27 positive group than in the HLA-B27 negative group. Systemic/periocular steroids were required in significantly more patients in the HLA-B27 positive group than in the HLA-B27 negative group (P=0.015). However, no significant differences were observed for final ocular and visual outcomes between these two groups. Associated systemic disease made no significant difference in the clinical features and prognosis in the HLA-B27 positive AU patients. In conclusion, despite more severe inflammation and a higher recurrence rate, HLA-B27 positive AU shows similar good final ocular and visual outcomes compared to HLA-B27 negative, idiopathic AU in a Korean population.

Inflammatory processes triggered by TCR engagement or by local cytokine expression: differences in profiles of gene expression and infiltrating cell populations

Immune cell-mediated inflammatory responses are triggered by TCR engagement with the target antigen, the initial event that brings about the complex sequence of events of the inflammatory process. Another form of inflammation is induced by local expression of certain cytokines. Unlike the former form of inflammation, little is known about the basic features of the cytokine-induced responses. Here, we analyzed tissue morphology, the infiltrating cells, and up-regulated, inflammation-related genes in mouse eyes in which inflammation is triggered by local transgenic (Tg) expression of cytokines and compared these features with those in eyes with experimental autoimmune uveitis (EAU), in which inflammation is initiated by engagement of TCR on sensitized T cells with their target antigen, followed by the well-defined, subsequent cytokine production. Eyes of IFN-gamma Tg mice exhibited severe, morphological changes but essentially no inflammation, and intense inflammation was found in eyes of interleukin (IL)-1 or IL-7 Tg mice. The cellular infiltration in eyes of these latter two lines of Tg mice resembled that in eyes with EAU by including many CD4 cells, but unlike in EAU, the infiltration in Tg eyes contained large proportions of B cells and only small numbers of macrophages. Real-time PCR analysis of eye RNA revealed differences among the disease models in the expression profiles of various inflammation-related genes. It is interesting that a bias toward T helper cell type 1 immunity (high IFN-gamma, RANTES/CCL5, MIG/CXCL9, and T-bet but low IL-4, IL-5, and GATA-3 transcripts) was found in EAU eyes but not in eyes of IL-1 and IL-7 Tg mice. The results thus show that similar to TCR engagement, local expression of certain cytokines triggers a complex, subsequent production of numerous inflammation-related molecules, but features of the ensued inflammatory process are determined by the triggering mechanism.

The level of thymic expression of RPE65 inversely correlates with its capacity to induce experimental autoimmune uveitis (EAU) in different rodent strains

We have previously shown that immunization with RPE65 produces in rats of four strains a severe inflammatory eye disease, designated experimental autoimmune uveitis (EAU). Here, we examined the uveitogenicity of RPE65 in six strains of mice. Only one strain, C57Bl/6, was found to develop consistently moderate levels of EAU, whereas other strains (BALB/c, B10.A, B10.BR, B10.RIII, C57BL/10J) were found to be essentially resistant to disease induced by RPE65. Analysis of the expression of RPE65 mRNA in thymi of the six mouse strains revealed detectable levels of the transcript in all strains, but with remarkable quantitative differences, with the lowest levels seen in thymi of C57Bl/6 mice, the only strain susceptible to RPE65-induced EAU. Moreover, unlike the finding with the mice, no RPE65 mRNA was detected in thymi of any of the four rat strains (Lewis, BN, F344, SHR) all of which are susceptible to the disease. These data thus indicate that the susceptibility to RPE65-induced EAU is inversely related to the thymic expression of the molecule. The data also suggest that this disease can be induced only in mice in which thymic expression of RPE65 is sufficiently low to allow the escape from deletion of T-cells with the adequate capacity to initiate the pathogenic immune response.

Central immunotolerance in transgenic mice expressing a foreign antigen under control of the rhodopsin promoter

PURPOSE

Different conclusions have been reached in recent studies concerning the immune response or tolerance of transgenic (Tg) mice expressing foreign antigens under control of retinal antigen promoters. The present study was aimed at analyzing the state of tolerance in Tg mice expressing hen egg lysozyme (HEL) under control of the rhodopsin promoter.

METHODS

Tg mice expressing HEL under control of the rhodopsin promoter (RhHEL-Tg) were generated and tested by conventional methods for immune responses against HEL. These Tg mice were also mated with Tg mice expressing HEL-specific receptor on their T lymphocytes and the double-Tg mice were examined for increased apoptosis in their thymi by the TUNEL assay, as well as for loss of HEL-specific T cells, by flow cytometry and proliferative response. The presence of HEL mRNA in mouse thymi was determined by RT-PCR.

RESULTS

RhHEL-Tg mice developed tolerance to HEL, shown by reduced cellular and humoral responses to HEL, as well as by the failure of ocular inflammation to develop after immunization with HEL. RhHEL-Tg mice expressed HEL mRNA in their thymus, and the tolerogenic mechanism in these mice was shown to be thymic deletion of HEL-specific T cells by the following observations in the double-Tg mice: (1) increased apoptosis in their thymi, (2) remarkable reduction in the proportion of the HEL-specific T cells, and (3) loss of lymphocyte response to low concentrations of HEL.

CONCLUSIONS

Tg mice expressing HEL under control of the rhodopsin promoter develop a tolerance for the foreign antigen, apparently as a result of thymic expression of HEL and deletion of T cells specific to this antigen.

The correlation between fluorescein angiographic and optical coherence tomographic features in clinically significant diabetic macular edema

PURPOSE

To assess the correlation between the features of optical coherence tomography (OCT) and fluorescein angiography in clinically significant diabetic macular edema.

DESIGN

Retrospective observational case series.

METHODS

This study involved 145 eyes (91 patients) with clinically significant diabetic macular edema. The fluorescein angiography features were categorized into focal leakage type, diffuse leakage type, and diffuse cystoid leakage type. The OCT features were categorized into four types: type 1, thickening with homogeneous optical reflectivity; type 2, thickening with markedly decreased optical reflectivity in the outer retinal layer; type 3A, foveolar detachment without traction; and type 3B, foveolar detachment with apparent vitreofoveal traction. The correlation between fluorescein angiography types and OCT types were analyzed, and their associations with visual acuity, central foveal thickness. and stages of diabetic retinopathy were evaluated.

RESULTS

The prevalence of OCT type 1 was higher in the focal leakage type (73.0%) and in the diffuse leakage type (58.9%) than in the diffuse cystoid leakage type (3.8%) of fluorescein angiography (P <.0001). The prevalence of OCT type 2 and 3A was higher in the diffuse cystoid leakage type (57.7% and 34.6%, respectively) than in the focal leakage type (20.6% and 3.2%) or diffuse leakage type(28.6% and 10.7%; P <.0001). The stages of retinopathy correlated with fluorescein angiography types (P =.016). Optical coherence tomography type 1 and the focal leakage type of fluorescein angiography showed the least foveal thickness and the best visual acuity (P <.05).

CONCLUSIONS

There was a significant correlation between the features of OCT and fluorescein angiography in clinically significant diabetic macular edema. The combined data from both OCT and fluorescein angiography may provide a clearer understanding of the anatomic and physiologic characteristics of clinically significant diabetic macular edema.

A new instrument for drainage or injection of fluid within subretinal space

PURPOSE

To describe a new instrument, the subretinal aspiration and injection device (SR-AID), designed to facilitate the controlled external drainage or injection of fluid in the subretinal space.

METHODS

The SR-AID is formed by an assembly of a probe, handle body, and a driving unit. The curved conduit within the probe segment forms a curved tunnel and acts as a guide along which a needle moves back and forth. The feasibility of fluid injection beneath the attached retina was tested in animal eyes. The efficacy of subretinal fluid drainage with the SR-AID were assessed in six cases of clinical retinal detachment.

RESULTS

External approach to the subretinal space under ophthalmoscopic monitoring can be achieved by oblique angle penetration of the scleral wall with a needle from the SR-AID. Fluid was injected successfully into the subretinal space in three of six rabbit eyes and in two of two pig eyes. The mean duration required for the drainage of subretinal fluid with the SR-AID was 127 seconds. There was no incidence of significant subretinal hemorrhage or retinal perforation in the animal experiments and in human cases.

CONCLUSION

Our case series suggests that the SR-AID provides an efficient and safe means of access to the subretinal space.

RPE65 is highly uveitogenic in rats

PURPOSE

To examine the hypothesis that RPE65, a protein specific to the retinal pigment epithelium, is uveitogenic in rats.

METHODS

Rats of four inbred strains (Lewis, Brown Norway, Fischer, and SHR) were immunized with native or recombinant bovine RPE65, or with S-antigen (S-Ag), emulsified with complete Freund adjuvant, and treated simultaneously with killed Bordetella pertussis bacteria, as indicated. Development of ocular changes was examined and scored both clinically and histologically.

RESULTS

Lewis rats immunized with RPE65 showed development of acute and severe inflammatory eye disease that affected most ocular tissues. The minimum uveitogenic dose of RPE65 was similar to that of S-Ag (1 microg per rat), but the changes induced by RPE65 at higher dose ranges were less severe than those induced by S-Ag. Concurrent treatment of the RPE65-immunized rats with B. pertussis bacteria was not critical for disease induction, but enhanced dramatically the pathogenic reaction. Unlike the results with several other retinal proteins, no pinealitis was detected in rats immunized with RPE65. Fischer (F344) rats resembled Lewis rats in being similarly affected by RPE65 or S-Ag. In contrast, Brown Norway (BN) rats developed severe disease when immunized with RPE65, but showed minimal changes in response to S-Ag. SHR rats responded poorly to disease induced by RPE65, and S-Ag-induced disease failed to develop.

CONCLUSIONS

RPE65 is highly uveitogenic in rats, thus suggesting that this molecule could be involved in pathogenic autoimmunity in the human eye.

Sensitivity of CD95-induced apoptosis in different proliferative status of human retinal pigment epithelial cells

It is known that CD95 (APO-1/Fas) is expressed on the cell surface, and apoptotic cell death can be induced by the CD95 ligation in the cultured, proliferating human retinal pigment epithelial (RPE) cells. However, little is known about CD95 on the non-proliferating RPE cells. In this study, human RPE cells were cultured up to 4 weeks after they reached the confluence, to simulate the non-proliferating RPE cells in situ. There was no significant difference in CD95 expression on the cell surface between the predominantly proliferating, preconfluent cells and predominantly non-proliferating, postconfluent cells in flow cytometric assays. However, unlike proliferating cells, no cellular death occurred in the predominantly non-proliferating cells after the treatment of agonistic anti-CD95 antibody with cycloheximide, pretreated with interferon-gamma. Our results suggest that the CD95/CD95L system probably plays a physiologic role in vivo to remove the abnormal, proliferating RPE cells, and factors other than the surface expression of CD95 may determine the sensitivity to the CD95 signals.

Macular hole surgery in conjunction with endolaser photocoagulation

PURPOSE

To determine whether endolaser photocoagulation to the retinal pigment epithelium at the base of a macular hole increases the anatomic success rate of surgery.

METHODS

In a prospective consecutive clinical trial, eight eyes of seven patients with idiopathic macular hole underwent vitrectomy with posterior cortical vitreous removal and peeling of visible epiretinal membrane when present. A single shot of argon endolaser photocoagulation was applied to the retinal pigment epithelium at the center of the macular hole with a duration of 0.05 to 0.2 seconds and an intensity of 50 to 200 mW. After fluid-gas exchange was performed with 14% perfluoropropane gas, patients maintained face-down positioning for 2 weeks.

RESULTS

One eye with stage 2 macular hole, six eyes with stage 3 macular hole, and one eye with stage 4 macular hole were included. All eight eyes had a closed macular hole (100% anatomic success rate) at final examination 6 to 12 months after surgery. Best-corrected visual acuity improved 3 or more lines on the Early Treatment Diabetic Retinopathy Study visual acuity chart in all eyes. Four (50%) of the eight eyes had a final visual acuity of 20/40 or better.

CONCLUSIONS

Endolaser photocoagulation may be a useful adjunct to macular hole surgery but requires further investigation and long-term evaluation.

CD99 (MIC2) regulates the LFA-1/ICAM-1-mediated adhesion of lymphocytes, and its gene encodes both positive and negative regulators of cellular adhesion

Despite the fact that integrin-mediated lymphocyte adhesion is a crucial event for an appropriate immune response, little is known about the mechanisms that control the adhesion and deadhesion processes generated by the engagement of CD99 between various types of immune cells. Here we report that the CD99 gene encodes two distinct proteins with opposite functions in the LFA-1/intercellular adhesion molecule 1 (ICAM-1)-mediated cell adhesion process. The two forms of the CD99 protein are produced by alternative splicing of the CD99 gene transcript. The major form induced homotypic adhesion of the human B lymphoblastoid cell line IM-9, whereas the minor, truncated form inhibited the adhesion process. Activation of the major form of CD99 with anti-CD99 monoclonal antibodies induced rapid aggregation of IM-9 cells, which was blocked by the addition of mAbs to LFA-1 or intracellular adhesion molecule 1. Overexpression of the minor truncated form of CD99 markedly down-regulated the expression of LFA-1. The two forms of CD99 are differentially expressed in most human cells tested and are highly conserved in monkey. Taken together, these observations suggest that the two forms of CD99 function in vivo in both positive and negative regulation of LFA-1-mediated adhesion of lymphocytes during an immune response.

CD99 (MIC2) regulates the LFA-1/ICAM-1-mediated adhesion of lymphocytes, and its gene encodes both positive and negative regulators of cellular adhesion

Despite the fact that integrin-mediated lymphocyte adhesion is a crucial event for an appropriate immune response, little is known about the mechanisms that control the adhesion and deadhesion processes generated by the engagement of CD99 between various types of immune cells. Here we report that the CD99 gene encodes two distinct proteins with opposite functions in the LFA-1/intercellular adhesion molecule 1 (ICAM-1)-mediated cell adhesion process. The two forms of the CD99 protein are produced by alternative splicing of the CD99 gene transcript. The major form induced homotypic adhesion of the human B lymphoblastoid cell line IM-9, whereas the minor, truncated form inhibited the adhesion process. Activation of the major form of CD99 with anti-CD99 monoclonal antibodies induced rapid aggregation of IM-9 cells, which was blocked by the addition of mAbs to LFA-1 or intracellular adhesion molecule 1. Overexpression of the minor truncated form of CD99 markedly down-regulated the expression of LFA-1. The two forms of CD99 are differentially expressed in most human cells tested and are highly conserved in monkey. Taken together, these observations suggest that the two forms of CD99 function in vivo in both positive and negative regulation of LFA-1-mediated adhesion of lymphocytes during an immune response.

Preretinal neovascularization induced by experimental retinal vein occlusion in albino rats

Retinal ischemia and neovascularization have been demonstrated in several animal models. To determine 1) whether the retinal or preretinal neovascularization can be induced in albino rats by retinal vein occlusion and 2) the type and rate of occurrence on neovascularization, we occluded retinal veins in albino rats by photodynamic thrombosis. After anesthesia, each of 36 rats received an injection of rose bengal photosensitive dye, and their veins underwent argon green laser treatment. Half or all the major retinal veins were occluded in 12 eyes and in 24 eyes, respectively. Ten control rats underwent the same procedures but the laser beam was directed between major retinal vessels. In 46 control eyes, rose bengal dye was seen to have perfused without laser treatment. Retinal detachment developed in most vein occluded eyes within one day of venous occlusion, which was confirmed by fluorescein angiography. On follow-up at two weeks, only four of 24 eyes (16.7%) had undergone occlusion of all retinal veins showed new preretinal vessels on the optic disc. In these four eyes, severe disturbance of both retinal arterial and venous blood flow was observed, but no other eyes showed such severe combined disturbance. These data suggest that preretinal neovascularization in albino rats can be induced by this minimally traumatic method and that venous occlusion is severe enough to compromise arterial blood flow for a certain threshold period, thus inducing the development of preretinal neovascularization.

Thymocytes positively select thymocytes in human system

We previously demonstrated the expression of MHC class II molecules in a significant percentage of human fetal and postnatal thymocytes. These results, at that time, raised the question as to whether the MHC class II molecules on immature thymocytes could actively be involved in the selection of immature T cells. We have developed a human reaggregate culture system to address this issue. Surprisingly, despite the fact that thymic epithelial cells (TECs) have been shown to be a major selecting cell type of positive selection, we were clearly able to see the involvement of MHC class II+ thymocytes during selection process through T-T interaction. In addition, maturation to single positive (SP) cells occurred only in the presence of MHC class II molecules and immature thymocytes were found to be arrested at the double positive (DP) stage of differentiation by blocking of TCR recognition of MHC class II molecules. All these results strongly suggest that human MHC class II+ thymocytes actively participate in the selection of the TCR repertoire, for which TCR recognition of peptide/MHC class II may be an initial determining step.

A tectonic keratoprosthesis using expanded polytetrafluoroethylene as a supporting skirt in humans

A tectonic keratoplasty was performed with a keratoprosthesis using expanded polytetrafluoroethylene as a supporting skirt, on the left eye of a 23-year-old woman who needed an emergency corneal transplantation due to corneal perforation. The keratoprosthesis implanted, consisted of a supporting skirt which was made of expanded polytetrafluoroethylene (PTFE), and an optic portion which was made of polymethylmethacrylate (PMMA). The optic portion and the supporting skirt were attached by cyanoacrylate tissue adhesive (Histoacryl). Two months post-operatively, the keratoprosthesis was extruded, leaving an opacified, vascularized cornea. A penetrating keratoplasty was performed 1 month later. The excised cornea was composed of granulation tissue. To our knowledge, this is the first case of tectonic keratoprosthesis using expanded PTFE as a supporting skirt in humans.