Deep learning segmentation of non-perfusion area from color fundus images and AI-generated fluorescein angiography

The non-perfusion area (NPA) of the retina is an important indicator in the visual prognosis of patients with branch retinal vein occlusion (BRVO). However, the current evaluation method of NPA, fluorescein angiography (FA), is invasive and burdensome. In this study, we examined the use of deep learning models for detecting NPA in color fundus images, bypassing the need for FA, and we also investigated the utility of synthetic FA generated from color fundus images. The models were evaluated using the Dice score and Monte Carlo dropout uncertainty. We retrospectively collected 403 sets of color fundus and FA images from 319 BRVO patients. We trained three deep learning models on FA, color fundus images, and synthetic FA. As a result, though the FA model achieved the highest score, the other two models also performed comparably. We found no statistical significance in median Dice scores between the models. However, the color fundus model showed significantly higher uncertainty than the other models (p < 0.05). In conclusion, deep learning models can detect NPAs from color fundus images with reasonable accuracy, though with somewhat less prediction stability. Synthetic FA stabilizes the prediction and reduces misleading uncertainty estimates by enhancing image quality.

Optical coherence tomography angiography in diabetic retinopathy: A major review

Diabetic retinopathy (DR) is characterized by retinal vasculopathy and is a leading cause of visual impairment. Optical coherence tomography angiography (OCTA) is an innovative imaging technology that can detect various pathologies and quantifiable changes in retinal microvasculature. We briefly describe its functional principles and advantages over fluorescein angiography and perform a comprehensive review on its clinical applications in the screening or management of people with prediabetes, diabetes without clinical retinopathy (NDR), nonproliferative DR (NPDR), proliferative DR (PDR), and diabetic macular edema (DME). OCTA reveals early microvascular alterations in prediabetic and NDR eyes, which may coexist with sub-clinical neuroretinal dysfunction. Its applications in NPDR include measuring ischemia, detecting retinal neovascularization, and timing of early treatment through predicting the risk of retinopathy worsening or development of DME. In PDR, OCTA helps characterize the flow within neovascular complexes and evaluate their progression or regression in response to treatment. In eyes with DME, OCTA perfusion parameters may be of predictive value regarding the visual and anatomical gains associated with treatment. We further discussed the limitations of OCTA and the benefits of its incorporation into an updated DR severity scale.

Fluorescein versus Indocyanine Green Angiography Guided Half-Dose Photodynamic Therapy for Chronic Central Serous Chorioretinopathy

Purpose

To compare the outcomes of fluorescein angiography (FA)-guided and indocyanine green angiography (ICGA)-guided half-dose photodynamic therapy (PDT) in patients with chronic central serous chorioretinopathy (CSC).

Methods

In this retrospective comparative study, medical records of eyes with chronic CSC who underwent half-dose PDT were reviewed. A retina specialist performed FA-guided half-dose PDT, and the other performed ICGA-guided treatment. The success of applying PDT in the resolution of subretinal fluid was compared between the FA- and ICGA-guided methods.

Results

Eighty-two eyes of 73 patients (41 eyes in each group) received half-dose PDT. After half-dose PDT, a significant improvement in the best-corrected visual acuity (BCVA) was found at the time of the last follow-up in both groups (both P < 0.001), with no significant intergroup difference. Central subfield and subfoveal choroidal thicknesses decreased significantly in both groups at the last follow-up (all P < 0.05), with no significant differences between the groups. Subretinal fluid (SRF) resolved in all eyes, and no persistent SRF was detected during the follow-up period.

Conclusion

FA-guided and ICG-guided half-dose PDT may have similar efficacy for the treatment of chronic CSC.

Documented Reperfusion of the Retina on Fluorescein Angiography after Administration of Intravenous Prostaglandin E1 for Central Retinal Artery Occlusion: A Case Report

Central retinal artery occlusion (CRAO) can result in devastating permanent vision loss. Presently, there is no evidence-based treatment for CRAO that is widely accepted. In the literature, multiple studies propose intravenous (IV) prostaglandin E1 (IV PGE1) as a potential treatment option for patients with CRAO. We illustrate 2 cases of CRAO successfully treated with IV PGE1. In both cases, our patients with vascular risk factors were diagnosed with CRAO of the left eye. They were started on twice daily IV 40 μg PGE1 in 100 mL normal saline, with each dose administered over 3 h. In the first case, we documented reperfusion of the retina on fluorescein angiography after administration of IV PGE1. In the second case, our patient improved from no light perception visual acuity (VA) to count fingers VA within 48 h of treatment with IV PGE1. Our study highlights the vasodilatory effect of IV PGE1. Due to its mechanism of action and safety profile, it should be considered a potential treatment option for CRAO. Further randomized controlled trials are necessary to determine the overall therapeutic effect of IV PGE1 for CRAO.

Optical Coherence Tomography Angiography Findings in Malignant Hypertensive Retinopathy

Purpose

To report the findings of fluorescein angiography (FA) and optical coherence tomography angiography (OCTA) in a patient with malignant hypertensive retinopathy.

Case Report

A 41year-old male was referred to our clinic with sudden visual loss in both of his eyes after an acute rise of blood pressure (200/150 mmHg). Optic disc swelling, flame shape hemorrhages especially around the optic disc, arterial narrowing, vessel tortuosity, cotton wool spots, hard exudate deposition, and multiple deep orange spots (Elschnig spots) were visible in both eyes. In the OCTA, disruption in the normal tapering patterns of the superficial and deep capillary plexuses was observed. Elschnig spots were observed as hypointense spots in the choriocapillaris slab. Leakage of the optic nerve head was seen in the FA.

Conclusion

When compared with the FA, the OCTA can illustrate the ischemic areas and the Elschnig spots with greater detail.

Long-term peripheral retinal vascular behavior in retinopathy of prematurity patients treated with ranibizumab intravitreal injection as monotherapy using fluorescein angiography

BACKGROUND

Few challenges are faced with the introduction of anti-VEGF agents as a modality of treatment for retinopathy of prematurity. The clinical behavior and time course of regression post injection differ compared to post laser ablation. This study aims to evaluate the long-term peripheral retinal vascularization outcome of Ranibizumab intravitreal injections monotherapy in the treatment of retinopathy of prematurity.

METHOD

Hospital-based quasi-experimental study. Include ROP patients who received intravitreal ranibizumab (IVR), as primary treatment for type 1 ROP. Patients were examined under general anaesthesia to ensure documentation of all junctions of vascular and avascular zones. Images were taken by RetCam III, Phoenix ICON and fluorescein angiography was performed to describe vascular behaviors.

RESULTS

The mean gestational age was 24.67 weeks and the mean postmenstrual age at the time of intravitreal ranibizumab treatment was 36.3 weeks. Fluorescein angiography was performed at 155-288 weeks; most eyes showed two disk diameters of avascular peripheral retina. Only eyes with original aggressive ROP who required a second injection (six eyes) showed extensive peripheral avascular retina reaching zone I (13.64%). Neovascularization was evident in five eyes (11.36%), all with an original aggressive ROP and received multiple injections.

CONCLUSIONS

Ranibizumab treated babies with incomplete retinal vascularization require close and long-term follow-up visits to assess post injection vascular behavior. Peripheral retinal avascular zone of more than two-disc diameters was present in most of the patients evidenced by fluorescein angiography. Babies with initial diagnosis of aggressive ROP are more likely to have persistent peripheral neovascularization.

Ultra-Widefield Fundus Fluorescein Angiography Findings in Patients with Fuchs' Uveitis Syndrome

Background

The aim of this study was to evaluate ultra-widefield (UWF) fundus fluorescein angiography (FFA) findings in patients with Fuchs' uveitis syndrome (FUS).

Materials and Methods

This cross-sectional study was conducted in patients with FUS. All the patients underwent a complete ophthalmologic examination, and FFA was carried out with Optos UWF retinal imaging. Standard FFA and image acquisition consisted of early phase (15-45 s) images, and late-phase (5-10 min) images were also obtained for both eyes.

Results

Forty eyes from twenty unilateral FUS patients, including 11 females (55%), who had a mean age of 38.50 ± 6.97 years, were enrolled. Eighty-five percent of the FUS eyes had optic disc hyperfluorescence (ODH) in the FFA. A significant relationship was observed between ODH and iris heterochromia (P = 0.004). ODH was seen in all the patients with iris heterochromia (n = 16). Peripheral vascular leakage (PVL), capillary nonperfusion, chorioretinal scar, and vascular sheathing were observed in 3, 3, 2, and 8 of the patients' eyes, respectively.

Conclusion

UWF FFA imaging seemed to be mandatory for evaluating the prognosis of the FUS patients, and another investigation may require to be conducted to evaluate the effect of antivascular endothelial growth factor agents for the management of PVL in these patients.

Fluorescein angiographic findings and Behcet's disease ocular attack score 24 (BOS24) as prognostic factors for visual outcome in patients with ocular Behcet's disease

Purpose

To determine the application of fluorescein angiographic (FA) findings and Behcet’s disease ocular attack score 24 (BOS24) scoring system in predicting poor visual outcome in patients with ocular Behcet’s disease.

Study design

Retrospective cohort study.

Methods

We included 73 eyes of 38 patients with ocular Behcet’s disease who underwent FA and reviewed FA images, anterior chamber cells, vitreous opacity, retinal and optic disc lesions, which are parameters in BOS24. The correlation between FA findings, BOS24, and visual acuity was assessed.

Results

Optic disc hyperfluoresence (74%), diffuse posterior pole leakage (52%) and diffuse peripheral leakage (52%) were the three most common findings. Common complications were peripheral capillary nonperfusion (29%), arterial narrowing (22%), and macular ischemia (19%). BOS24 scores of ≥ 6 (p < 0.0001), arterial narrowing (p < 0.0001), and severe posterior pole leakage (p = 0.004) were significantly associated with poor visual outcome. Combining significant FA findings: arterial narrowing and severe posterior pole leakage, to BOS24 ≥ 6 results in an increased relative risk of developing poor visual acuity from 7.30 to 10.43 and 1.89 to 2.02 respectively.

Conclusion

Fluorescein angiography is an important investigation for predicting poor visual outcome. BOS24 may be a useful alternative when fluorescein angiographic is unavailable.

Structural and Functional Imaging of the Retina in Central Retinal Artery Occlusion - Current Approaches and Future Directions

Central retinal artery occlusion (CRAO) is a form of acute ischemic stroke which affects the retina. Intravenous thrombolysis is emerging as a compelling therapeutic approach. However, it is not known which patients may benefit from this therapy because there are no imaging modalities that adequately distinguish viable retina from irreversibly infarcted retina. The inner retina receives arterial supply from the central retinal artery and there is robust collateralization between this circulation and the outer retinal circulation, provided by the posterior ciliary circulation. Fundus photography can show canonical changes associated with CRAO including a cherry-red spot, arteriolar boxcarring and retinal pallor. Fluorescein angiography provides 2-dimensional imaging of the retinal circulation and can distinguish a complete from a partial CRAO as well as central versus peripheral retinal non-perfusion. Transorbital ultrasonography may assay flow through the central retinal artery and is useful in the exclusion of other orbital pathology that can mimic CRAO. Optical coherence tomography provides structural information on the different layers of the retina and exploratory work has described its utility in determining the time since onset of ischemia. Two experimental techniques are discussed. 1) Retinal functional imaging permits generation of capillary perfusion maps and can assay retinal oxygenation and blood flow velocity. 2) Photoacoustic imaging combines the principles of optical excitation and ultrasonic detection and - in animal studies - has been used to determine the retinal oxygen metabolic rate. Future techniques to determine retinal viability in clinical practice will require rapid, easily used, and reproducible methods that can be deployed in the emergency setting.

Photopigment Bleaching Phenomenon on Fluorescein Angiography in a Patient with Impending Central Retinal Vein Occlusion

Purpose

To present the second case of photopigment bleaching phenomenon in fluorescein angiography (FA) and the first case of this phenomenon due to impending central retinal vein occlusion (CRVO).

Case Report

A 32-year-old healthy female noticed blurred vision in her right eye one day before presentation. Despite the 20/20 visual acuity at presentation, mild increased retinal vascular tortuosity and unilateral photopigment bleaching phenomenon in FA was observed in the right eye. Three weeks later, she developed a complete CRVO with visual acuity reduction to 20/40 that responded well to the intravitreal injection of aflibercept.

Conclusion

Impending CRVO can cause unilateral photopigment bleaching phenomenon in FA that may be due to retinal ischemia.

Treatment of Noninfectious Retinal Vasculitis Using Subcutaneous Repository Corticotropin Injection

Purpose

To show whether subcutaneous repository corticotropin injection (RCI, Acthar® Gel, a repository corticotropin injection, can be an effective potential therapeutic agent for noninfectious retinal vasculitis.

Methods

Patients with active retinal vasculitis were followed with serial ultra-wide-field fluorescein angiograms and treated with 80 units of subcutaneous repository corticotropin injection twice weekly.

Results

Primary outcome of ≥50% improvement in response level (RL) for retinal vasculitis and percent improvement in retinal vasculitis severity scoring (RVSS) by more than one quartile (≥25%) at week 12 was met in 15 and 16 of the 30 total eyes, respectively, including 1 eye with severe retinal vasculitis in each group. Complete resolution of retinal vasculitis was seen in seven eyes with a mean time of 17.1 weeks. Intraocular pressure elevation requiring therapy and cataract progression were noted in two and three eyes, respectively. One patient stopped medication due to side effects (injection site reaction).

Conclusion

Repository corticotropin injection was well-tolerated overall. Repository corticotropin injection may be an effective therapeutic agent in the treatment of noninfectious retinal vasculitis.

A Novel Method to Detect and Monitor Retinal Vasculitis Using Swept-Source OCT Angiography

PURPOSE

To introduce a novel method for assessment of retinal vasculitis using swept-source OCT angiography (SS-OCTA).

DESIGN

Retrospective case series.

PARTICIPANTS

Patients with retinal vasculitis.

METHODS

The subjects were identified among the clinic population and imaged with 12 × 12-mm SS-OCTA scans centered on the fovea. A custom retina segmentation superimposed the color retinal thickness map on a modified en face flow scan. Findings from en face flow scans were correlated with localized perivascular retinal thickening on B-scans. Results from SS-OCTA were compared with fluorescein angiography (FA) to examine the proportion of perivascular thickening to retinal vascular leakage or staining.

RESULTS

Twenty-one patients with retinal vasculitis underwent same-day FA and SS-OCTA. Visible retinal vascular leakage/staining on FA corresponded to increased perivascular retinal thickness on SS-OCTA in 17 patients. Five patients had a second examination with same-day FA and SS-OCTA after treatment of the vasculitis. Three of those 5 patients showed improved retinal vascular leakage/staining on post-treatment FA and decreased perivascular retinal thickness on SS-OCTA scans.

CONCLUSIONS

Swept-source OCT angiography detects structural retinal thickening secondary to inflammatory retinal vascular leakage. Further studies are required to confirm whether SS-OCTA may serve as a semiquantitative alternative to FA to diagnose and monitor the response to treatment in patients with retinal vasculitis.

Multimodal Imaging Characteristics of a Large Retinal Capillary Macroaneurysm in an Eye With Severe Diabetic Macular Edema: A Case Presentation and Literature Review

Though microaneurysms are the hallmark of diabetic retinopathy (DR), large aneurismal changes termed as ''macroaneurysms'' (MAs) may also occur in the course of chronic diabetic macular edema. MAs are usually accompanied by intraretinal hard exudates, fluid accumulation and retinal hemorrhages. Detection of MAs is clinically important as it implies that macular edema is usually chronic and therefore can be resistant to intravitreal anti-vascular endothelial growth factor injections. Multimodal imaging consisting of fluorescein angiography (FA), indocyanine green angiography (ICGA), optical coherence tomography (OCT) or OCT-angiography (OCTA) can be performed to detect and understand the nature of MA and thereby select proper treatment modality. Herein, we report multimodal imaging features of a 64-year-old woman with insulin-dependent diabetes mellitus presented with treatment naïve severe macular edema and a macroaneurysm at the right temporal macula. In conclusion, FA, ICGA and OCT seem to be far superior to OCTA to detect these lesions due to probable slow flow inside the MA.

Comparison of Retinal and Choroidal Involvement in Sarcoidosis-related Chorioretinitis Using Fluorescein and Indocyanine Green Angiography

Purpose:

To compare the involvement of the retina with that of the choroid in ocular sarcoidosis (OS) using dual fluorescein angiography (FA)/indocyanine green angiography (ICGA).

Methods:

A retrospective study of 23 patients with the diagnosis of OS was performed. Angiographic signs were quantified following the established FA/ICGA scoring system for uveitis.

Results:

The choroid was predominantly involved in 19 (82.6%) patients or 87% (40/46) of the eyes, and the retina in 2 (8.7%) patients or 13% (6/46) of the eyes. The mean angiographic score was 7.15 ± 4.5 for the retina (FA) compared to 14.02 ± 4.86 for the choroid (ICGA) (P < 0.0001). In 13% (3/23) of patients, FA did not show retinal inflammation, whereas ICGA was strongly positive, revealing occult choroidal lesions.

Conclusion:

The choroid is preferentially involved in OS, for which ICGA is the examination of choice. There is a risk of underestimating the global ocular involvement and of missing choroidal involvement if only FA is used. FA/ICGA scoring system allows for quantitative assessment of inflammation in the posterior uvea that occurs in OS; therefore, the system can be useful to quantitatively monitor outcomes in clinical trials.

Contribution of Dual Fluorescein and Indocyanine Green Angiography to the Appraisal of Presumed Tuberculous Chorioretinitis in a Non-endemic Area

PURPOSE

To assess the respective involvement of retina versus choroid in presumed ocular tuberculosis (POT) in a non-endemic area using dual fluorescein (FA) and indocyanine green angiography (ICGA).

METHODS

We retrospectively analyzed cases diagnosed with POT at the Centre for Ophthalmic Specialized Care, Lausanne, Switzerland. Angiography signs were quantified using an established dual FA and ICGA scoring system for uveitis.

RESULTS

Out of 1739 uveitis patients visited from 1995 to 2014, 53 (3%) were diagnosed with POT; of whom 28 patients (54 eyes) had sufficient data available to be included in this study. Of 54 affected eyes, 39 showed predominant choroidal involvement, 14 showed predominant retinal involvement and one had equal retinal and choroidal scores. Mean angiographic score was 6.97 ± 5.08 for the retina versus 13.48 ± 7.06 for the choroid (P < 0.0001). For patients with sufficient angiographic follow-up after combined anti-tuberculous and inflammation suppressive therapy, mean FA and ICGA scores decreased from 6.97 ± 5.08 to 3.63 ± 3.14 (P = 0.004), and 13.48 ± 7.06 to 7.47 ± 5.58 (P < 0.0001), respectively.

CONCLUSION

These results represent the first report of the respective contributions of retinal and choroidal involvement in POT. Choroidal involvement was more common, for which ICGA is the preferred examination. In cases of compatible uveitis with positive results of an interferon-gamma release assay, particularly in a region that is non-endemic for TB, dual FA and ICGA should be performed to help establish the diagnosis of ocular tuberculosis and improve follow-up.

Multifocal Choroiditis and Panuveitis - difficulties in diagnosis and treatment

We present the case of a 49-year-old patient who was treated with Aripriprazole in context of Paranoid Schizophrenia. The patient had a history of numerous Panuveitis recurrences for the left eye, which led to a marked decrease of the vision VA-NLP and was diagnosed with Multifocal Choroiditis and Panuveitis for the right eye. The examination revealed VA of 20/ 200 for right eye, keratic precipitates, and vitritis. Fundus aspect of the right eye showed multiple discrete, ovoid, yellowish-grey lesions at the posterior pole and periphery, optic disc oedema was present. The Human leukocyte antigen typing of group A, ancillary investigation (OCT, Angiofluorography, B-mode ultrasonography) and fundus examination confirmed the diagnosis of Multifocal Choroiditis and Panuveitis but we did not exclude antipsychotic-related chorioretinopathy or a Birdshot-like Syndrome.

Single-dose Intravitreal Bevacizumab after Complete Panretinal Photocoagulation in Proliferative Diabetic Retinopathy: an Effective Adjunctive Treatment

Patients with proliferative diabetic retinopathy (PDR) who are refractory to complete panretinal photocoagulation (PRP) have a high risk of severe vision loss. The aim of this study was to evaluate the effectiveness of single-dose intravitreal bevacizumab (IVB) after complete PRP in patients with refractory PDR. Patients with retinal neovascularization (NV) secondary to diabetes mellitus and refractory to complete PRP were enrolled in this study. All patients received a single dose of 1.25 mg IVB at 3 months after completing the PRP. Patients underwent complete ophthalmic evaluation and fluorescein angiography (FA) at baseline and 1 month after injection. The main outcome measure was a reduction in the areas of leakage (mm²) on FA. All patients were evaluated at baseline and on every visit at 1 day, 1 week, and 1 month after the injection. A total of 21 consecutive patients (32 eyes) with PDR completed this study. Thirteen (61.9%) patients were female. The mean ± standard deviation (SD) age was 64.1 ± 5.6 years. Complete and partial response of angiographic leakage of NV was noted in 7 (21.9%) and 18 (56.2%) of 32 eyes after a single IVB injection, respectively. No satisfactory response of retinal NV was observed in 7 eyes (21.9%) at 1 month after the injection. No significant ocular or systemic adverse events were observed. A single-dose of IVB could be associated with a satisfactory response of retinal NV, secondary to PDR, in patients who are refractory to complete PRP.

Central Serous Chorioretinopathy Misdiagnosed as Posterior Uveitis and the Vicious Circle of Corticosteroid Therapy

Purpose:

To determine the proportion of patients with central serous chorioretinopathy (CSCR) mistaken for posterior uveitis and to identify the deleterious consequences.

Methods:

Charts of 1,657 patients admitted in the section of inflammatory eye diseases at the Center for Ophthalmic Specialized Care (COS) in Lausanne, Switzerland from 1995 to 2013 were reviewed. CSCR cases misdiagnosed as posterior uveitis or those with superimposed disease due to steroid therapy for uveitis were studied. Delay in diagnosis, specific erroneous uveitis diagnosis and evolution of the disease were also evaluated. Retrospectively, the most useful means for a correct diagnosis of CSCR were the original fluorescein angiography (FA), indocyanine green angiography (ICGA) and optical coherence tomography (OCT) when available.

Results:

Out of a total of 1,657 patients, 15 (0.9%) cases with CSCR were identified. These included 12 subjects misdiagnosed as posterior uveitis and 3 uveitis subjects with superimposed CSCR following corticosteroid therapy for uveitis. The presentation of the disease was largely influenced by improper and continued use of corticosteroids.

Conclusion:

CSCR is a rare but not negligible misdiagnosis in posterior uveitis representing approximately 1% of subjects from a collective series of uveitis cases at a referral center. Investigative measures such as FA, ICGA and OCT are crucial for reaching a correct diagnosis and avoiding disease aggravation due to corticosteroid therapy.

Application of different imaging modalities for diagnosis of Diabetic Macular Edema: A review

Diabetic Macular Edema (DME) is caused by accumulation of extracellular fluid from hyperpermeable capillaries within the macula. DME is one of the leading causes of blindness among Diabetes Mellitus (DM) patients. Early detection followed by laser photocoagulation can save the visual loss. This review discusses various imaging modalities viz. biomicroscopy, Fluorescein Angiography (FA), Optical Coherence Tomography (OCT) and colour fundus photographs used for diagnosis of DME. Various automated DME grading systems using retinal fundus images, associated retinal image processing techniques for fovea, exudate detection and segmentation are presented. We have also compared various imaging modalities and automated screening methods used for DME grading. The reviewed literature indicates that FA and OCT identify DME related changes accurately. FA is an invasive method, which uses fluorescein dye, and OCT is an expensive imaging method compared to fundus photographs. Moreover, using fundus images DME can be identified and automated. DME grading algorithms can be implemented for telescreening. Hence, fundus imaging based DME grading is more suitable and affordable method compared to biomicroscopy, FA, and OCT modalities.

Imaging in diabetic retinopathy

While the primary method for evaluating diabetic retinopathy involves direct and indirect ophthalmoscopy, various imaging modalities are of significant utility in the screening, evaluation, diagnosis, and treatment of different presentations and manifestations of this disease. This manuscript is a review of the important imaging modalities that are used in diabetic retinopathy, including color fundus photography, fluorescein angiography, B-scan ultrasonography, and optical coherence tomography. The article will provide an overview of these different imaging techniques and how they can be most effectively used in current practice.

New parametric imaging method with fluorescein angiograms for detecting areas of capillary nonperfusion

Objectives

Fluorescein angiography (FAG) is currently the most useful diagnostic modality for examining retinal circulation, and it is frequently used for the evaluation of patients with diabetic retinopathy, occlusive diseases, such as retinal venous and arterial occlusions, and wet macular degeneration. This paper presents a method for objectively evaluating retinal circulation by quantifying circulation-related parameters.

Methods

This method allows the semiautomatic preprocessing and registering of FAG images. The arterial input function is estimated from the registered set of FAG images using gamma-variate fitting. Then, the parameters can be computed by deconvolution on the basis of truncated singular value decomposition, and they can finally be presented as parametric color images in a combination of three colors, red, green, and blue.

Results

After the estimation of arterial input function, the parameters of relative blood flow and mean transit time were computed using deconvolution analysis based on truncated singular value decomposition.

Conclusions

The parametric color image is helpful to interpret the status of retinal blood circulation and provides quantitative data on retina ischemia without interobserver variability. This system easily provides the status of retinal blood circulation both qualitatively and quantitatively. It also helps to standardize FAG interpretation and may contribute to network-based telemedicine systems in the future.

The effect of fluorescein angiography on full-field electroretinography parameters

PURPOSE

To investigate the effect of simultaneously performed fluorescein angiography (FA) on full-field electroretinography (ffERG) parameters.

METHOD

Scotopic and photopic ffERG were performed immediately and 60 minutes after conventional FA in patients with retinal photoreceptor disorders; a-and b-wave amplitudes were compared between recordings obtained at the two time intervals in each patient.

RESULTS

Ten eyes of five (3 male and 2 female) patients with mean age of 19.6±3.8 (range, 15-25) years were studied. Intravenous fluorescein administration caused an immediate reduction in ERG waves which was most prominent in rod and maximal combined responses. Mean a-wave amplitude in maximal combined response, rod response and cone response ERGs was 46.0±18.8, 8.0±7.0 and 5.1±2.0 mv immediately after FA which was increased to 79.0±30.0, 21.5± 22.5 and 6.5±2.4 mv 60 minutes afterwards, respectively (P<0.005 for all comparisons). Mean b-wave amplitude in the same order was 91.0±17.5, 47.7±17.2 and 17.3±14.7mv which was increased to 145.0±54.3, 91.8±48.1 and 20.0±17.7 mv respectively, 60 minutes after FA (P<0.005 for all comparisons).

CONCLUSION

The amplitude of ERG a- and b-waves under scotopic and photopic conditions increased significantly one hour after FA. These changes may be explained by disappearance of phototoxic and bleaching effects of strong light exposure from the light source of the angiography machine and fluorescein molecule on retinal photoreceptors.

Differential diagnosis of retinal vasculitis

Retinal vaculitis is a sight-threatening inflammatory eye condition that involves the retinal vessels. Detection of retinal vasculitis is made clinically, and confirmed with the help of fundus fluorescein angiography. Active vascular disease is characterized by exudates around retinal vessels resulting in white sheathing or cuffing of the affected vessels. In this review, a practical approach to the diagnosis of retinal vasculitis is discussed based on ophthalmoscopic and fundus fluorescein angiographic findings.

Slow versus Rapid Fluorescein Injection in Angiographic Studies for Retinal Vascular Disorders

PURPOSE

To compare the incidence of adverse reactions following rapid versus slow fluorescein injection for fundus angiography.

METHODS

This randomized controlled trial was performed on 500 patients with retinal vascular disorders. Subjects with central serous retinopathy, age-related macular degeneration and retinal pigment epithelial changes were excluded. Pregnancy, asthma, allergic diseases and previous history of reactions to fluorescein were other exclusion criteria. Patients were randomly divided into two equal groups who received slow infusion of dye (over 15-25 seconds) versus the usual rapid injection (in 5-8 seconds), and were compared for adverse effects.

RESULTS

Overall, 47 (9.4%) patients including 34 (13.6%) subjects in the rapid group and 13 (5.2%) cases in the slow group developed adverse reactions (P=0.001, relative risk=2.6). All adverse reactions were categorized as mild; no instance of moderate or severe reactions was observed. There was a lower incidence of nausea and vomiting with slow infusion of fluorescein (P=0.02), however no statistically significant difference was observed in the frequency of vertigo and vasovagal reactions between the study groups.

CONCLUSION

Slow fluorescein injection during fundus angiography, instead of the usual rapid application, can be an effective way to reduce the incidence of nausea and vomiting in patients whose first phase of angiography is of little diagnostic importance.