Choroidal Perfusion Research Articles

Role of Nitric Oxide in Choroidal Blood Flow Regulation during Light/Dark Transitions

Several studies have recently shown that a transition from light to dark is associated with a reduction in choroidal blood flow. The mechanism underlying this effect is unclear but may be related to changes in neural input. In the present study, the authors hypothesized that either the alpha-receptor agonist phenylephrine or the nitric oxide synthase (NOS) inhibitor L-NMMA may alter the choroidal blood flow response during a transition from light to dark. In 15 healthy male nonsmoking subjects, the response of choroidal perfusion was studied in a randomized placebo-controlled three-way crossover study. Phenylephrine, L-NMMA or placebo was administered on different study days, and the effect of a light/dark transition on choroidal perfusion parameters was studied. Subfoveal choroidal blood flow and fundus pulsation amplitude were assessed with laser Doppler flowmetry and laser interferometry, respectively. Before drug administration, a transition from light to dark reduced both choroidal hemodynamic parameters by 11% to 20%. Neither phenylephrine nor placebo altered basal choroidal blood flow or choroidal blood flow responses to the light/dark transitions. By contrast, the NOS inhibitor L-NMMA significantly reduced basal choroidal blood flow by 20.5% +/- 5.9% (P < 0.001) and basal fundus pulsation amplitude by 21.5% +/- 4.8% (P < 0.001). In addition, the response of subfoveal choroidal blood flow (-6.2% +/- 3.2%; P = 0.008) and fundus pulsation amplitude (-4.2% +/- 2.4%; P < 0.001) to the light/dark transition was significantly diminished. The present study indicates that NO plays a role in the choroidal blood flow decrease during a transition from light to dark. Given that L-NMMA is a nonspecific inhibitor of NOS, the present study does not clarify whether this NO is from endothelial or neural sources.

Three-Dimensional Angiography of Classic and Occult Lesion Types in Choroidal Neovascularization

To identify characteristic features of classic and occult choroidal neovascularization (CNV) by using a novel technique of topographic angiography for three-dimensional (3D) visualization. A confocal scanning laser ophthalmoscope (SLO, Heidelberg Retina Angiograph; Heidelberg Engineering, Dossenheim, Germany) was used to perform fluorescein (FA) and indocyanine green (ICGA) angiography in158 patients. Ninety-four eyes had predominantly classic and 64 eyes had occult lesions. With an image frequency of 20 Hz, a tomographic series of 32 images per set were taken over a depth of 4 mm. Axial analyses for each x/year position were performed, to determine the fluorescence distribution along the z-axis. After the axial location of hyperfluorescence was detected, a depth profile was generated. All results were integrated into a gray-scale-coded depth image and imaged as a 3D relief. Characteristic features of classic and occult lesions were distinguished. Classic CNV appeared as a well-demarcated lesion with steep, prominent borders, often craterlike, and frequently surrounded by a halo, suggesting choroidal perfusion changes. Occult CNV was documented by 3D as a convex lesion with flat, ill-defined borders and without any surrounding halo. Topographic imaging is superior to conventional angiography regarding definition of lesion type, configuration, and extension, because masking phenomena do not interfere. Topographic angiography allows a realistic 3D representation of CNV. Characteristic features based on the neovascular architecture and the differences in leakage behavior of different lesion types are clearly identified.

Retinal fluorescein and indocyanine green angiography and optical coherence tomography in successive stages of Vogt-Koyanagi-Harada disease

To report features of retinal fluorescein (FA) and indocyanine green (ICGA) angiography and optical coherence tomography (OCT) at successive stages of Vogt-Koyanagi-Harada (VKH) disease. FA and ICGA were systematically performed in cases of VKH disease, at admission, 1 month later, and at the end of the follow-up. In addition, the most recent patients underwent OCT. In the follow-up, the clinical evolution and extent of treatment were related to the angiographic and tomographic features. FA and ICGA showed a diffuse delayed choroidal perfusion, including a delayed arterial, choriocapillar, and venous filling. This delayed choroidal perfusion involved the posterior pole and the hole periphery. The classically described serous retinal detachments were slowly filled from numerous pin points that could correspond to leakage through areas of damaged retinal pigment epithelium due to the choroidal ischemia. An uneven background choroidal fluorescence visible at the mid phase of ICGA was the result of multiple hypofluorescent round lesions in the choroidal stroma. Choroidal folds appeared hypofluorescent in FA and hyperfluorescent in ICGA. Some of these angiographic findings were present at the very early neurologic stage of the disease. Moreover, under treatment, a persisting altered choroidal perfusion could increase the incidence of retinal detachment relapses. Various pathological conditions are characterized by choroidal involvement and serous retinal detachment. Angiographical findings may be helpful in the diagnosis. FA coupled with ICGA can be an useful tool in the early diagnosis of VKH disease as well as during the tapering of immunosuppressive drugs.

Giant cell arteritis with normal inflammatory markers

Editor, G iant cell arteritis (GCA) is a neuro-ophthalmological emergency given the risk of permanent, severe visual loss if left untreated (Hayreh et al. 1998a). We present a rare case of biopsy-proven GCA with normal inflammatory markers at first presentation. A 74-year-old woman was referred to us with a 2 month history of rightsided temporal headaches. She had no relevant past medical history but her sister suffered from polymyalgia rheumatica. The headaches occurred almost daily and often lasted several hours. She reported no visual symptoms, jaw claudication or other classical symptoms of polymyalgia rheumatica or GCA. Her Snellen visual acuity was 6 ⁄ 6 in both eyes and ocular examination was entirely normal. Her temporal arteries on both sides were pulsatile, non-tender and normal in appearance. Inflammatory markers were requested to rule out GCA; these were normal, with an erythrocyte sedimentation rate (ESR) of 30 mm ⁄hr and a C-reactive protein (CRP) <5 mg ⁄L. The patient was therefore discharged from clinic. She re-presented 6 months later, still complaining of right-sided temporal headaches, but over the past 3 months she had also become aware of scalp tenderness, transient episodes of jaw ache and feeling tired. She again denied any visual disturbance, and ocular examination was unremarkable. However, her right temporal artery was now thickened, although non-tender and still pulsatile. Inflammatory markers were raised with an ESR of 96 mm ⁄hr and a CRP of 18 mg ⁄L. Other routine bloods, including a full blood count, were normal. She was started on 60 mg of oral prednisolone, and a right temporal artery biopsy (TAB) showed unequivocal histological features of GCA. Her symptoms resolved completely on steroids and, a year later, there has been no disease recurrence as her treatment has been tapered down. This case illustrates an atypical, insidious presentation of GCA. The recent onset of unilateral temporal headaches, its persistence and the subsequent development of other clinical features indicate an evolution of the underlying pathological process. The normal inflammatory markers and absence of other systemic and ocular symptoms could be explained by localized involvement of her temporal arteries. Temporal headache is the most common clinical symptom of GCA and is reported by up to 90% of patients (Rahman & Rahman 2005). In Jonasson’s series of 124 biopsy-proven cases, a higher ESR and more generalized systemic features were also associated with longer disease duration (Jonasson et al. 1979). Although an ESR is frequently requested by clinicians in order to rule out this condition, a normal level has been reported in 5–30% of patients with GCA (Rahman & Rahman 2005). In Hayreh’s series of 363 patients who had TAB for suspected GCA, CRP was more sensitive (100%) than ESR (92%) in detecting GCA, and a combination of ESR and CRP gave the best specificity (97%) (Hayreh et al. 1997). It is also well established that patients with occult GCA can have significantly lower inflammatory markers compared to those with the more classical systemic features (Hayreh et al. 1998b). Recently, Poole and colleagues presented a unique case of occult GCA with normal ESR and CRP (Poole et al. 2003). Their patient had transient episodes of monocular visual loss and evidence of ocular ischaemia with ophthalmoplegia, cotton wool spots and a markedly delayed choroidal perfusion on fluorescein angiography. These findings raised the possibility of GCA, which was confirmed with a positive TAB. As in our case, this highlights the importance of TAB as the gold-standard diagnostic test in GCA since inflammatory markers can be normal if the disease process is at an early stage, there is only localized arteritis or there is an inability to mount an acute-phase serologic response. GCA is a heterogeneous disease with a wide range of clinical manifestations. It remains a challenging diagnosis, requiring a high index of clinical suspicion and a low threshold for TAB.

Cellular Physiology of Retinal and Choroidal Arteriolar Smooth Muscle Cells

Control of ocular blood flow occurs predominantly at the level of the retinal and choroidal arterioles. The present article provides an overview of the Ca2 + handling mechanisms and plasmalemmal ion channels involved in the regulation of retinal and choroidal arteriolar smooth muscle tone. Increases in global intracellular free Ca2 + ([Ca2 +]i) involve multiple mechanisms, including agonist-dependent release of Ca2 + from intracellular stores through activation of the inositol trisphosphate (IP3) pathway. Ca2 + enters by voltage-dependent L-type Ca2 + channels and novel dihydropyridine-sensitive store-operated nonselective cation channels. Ca2 + extrusion is mediated by plasmalemmal Ca2 +-ATPases and through Na+/Ca2+ exchange. Local Ca2 + transients (Ca2 + sparks) play an important excitatory role, acting as the building blocks for more global Ca2 + signals that can initiate vasoconstriction. K+ and Cl- channels may also affect cell function by modulating membrane potential. The precise contribution of each of these mechanisms to the regulation of retinal and choroidal perfusion in vivo warrants future investigation.

Choroidal perfusion delay and hyperpermeability in exudative retinal detachment induced by panretinal scatter photocoagulation.

Choroidal perfusion delay and hyperpermeability in exudative retinal detachment induced by panretinal scatter photocoagulation.

Choroidal Ischemia After Photodynamic Therapy With Verteporfin for Choroidal Neovascularization

To report delay in choroidal perfusion suggestive of ischemia after photodynamic therapy (PDT) with verteporfin for choroidal neovascularization (CNV). Observational case series. Retrospective review of all patients who developed choroidal ischemia after PDT. This vascular change was found in eight (2.1%) of 373 eyes of patients treated for CNV as a result of age-related macular degeneration (AMD) and in one (0.9%) of 114 eyes treated for pathologic myopia. A decrease of 3 lines of vision was reported to occur one week after treatment in patients with AMD. At the 12-month examination, patients did not exhibit any marked changes in visual acuity. Choroidal ischemia was an uncommon manifestation owing to the selectivity of verteporfin therapy and the existence of abundant anastomotic vascular connections in the choroid. The low incidence of this vascular event should not preclude counseling PDT in eyes that could benefit greatly from this therapy.

Dynamische Konturtonometrie

Dynamic contour tonometry (DCT) is a new technology for noninvasive and direct measurement of intraocular pressure (IOP); its results are thought to be influenced less than those of other methods by structural characteristics of the eye. The curvature of the pressure sensing device is concave and only slightly flatter than that of the human cornea. The cornea adapts to the curvature of the transducer head, and the sensor in the centre of the adapted area measures the pressure on the other side of the cornea in the force-free range. Studies published so far suggest that DCT is less heavily dependent than applanation tonometry on the biomechanical properties of the cornea . A further advantage of DCT over other forms of tonometry is the capability of dynamic measurements over time. It is also possible to measure both the diastolic and the systolic IOD and determine the difference between the two, i.e. the ocular pulse amplitude (OPA). OPA is an indirect indicator of choroidal perfusion and reflects the condition of the arterial vascular system and the action of the heart. It could be important in the diagnosis and treatment of glaucoma.

Case series: Monocular visual loss associated with subarachnoid hemorrhage secondary to ruptured intracranial aneurysms

To describe variations in the presentation of monocular visual loss associated with intracranial aneurysm rupture. The clinical course, possible etiologies and management of visual loss in three patients are described. The first patient developed Terson's syndrome (vitreal hemorrhage associated with raised intracranial pressure secondary to subarachnoid hemorrhage). Following aneursymal clipping, her postoperative management was conservative and there was no improvement in visual acuity. The second patient underwent surgical clipping of internal carotid aneursysms and sustained visual loss subsequent to surgical dissection and temporary clipping around the optic nerve and anterior choroidal artery. The vessel subsequently thrombosed. Potential contributing factors to visual loss in this case included intraoperative hypotension and anemia. This patient received anti-platelet medications, and experienced subsequent improvement in visual acuity to 6/9. A third patient underwent a right orbito-frontal keyhole craniotomy with the cranial flap retracted across the orbit. Elevated intraocular pressure secondary to external orbital compression may have compromised retinal and choroidal perfusion. This patient also developed vasospasm of both anterior cerebral arteries which resolved partially with papaverine therapy. Hypertension-hypervolemia therapy was instituted, with subsequent partial recovery of visual acuity in her right eye. Perioperative monocular visual loss associated with intracranial aneurysm repair is an infrequent occurrence, and clinical presentations may be quite variable. The primary pathophysiological mechanisms are intraocular hemorrhage and ischemia of ocular structures, including the optic nerve. Early detection, via regular fundoscopic examination and treatment aimed at decreasing intraocular pressure and augmenting ocular perfusion may improve outcomes.

Influence of Treatment Parameters on Selectivity of Verteporfin Therapy

To improve selectivity of verteporfin therapy (PDT) in neovascular age-related macular degeneration (AMD) using modified treatment parameters. Nineteen consecutive patients with predominantly classic choroidal neovascularization (CNV) in AMD were treated with 6 mg/m2 verteporfin given as bolus infusion. Patients received PDT with a fluence of either 25 or 50 J/cm2. Choroidal perfusion changes were evaluated by indocyanine green angiography (ICGA) at baseline, day 1, week 1, week 4, and month 3. Secondary outcomes were CNV closure rate and therapy-induced leakage documented by fluorescein angiography (FA). The safety of the treatment was assessed with ETDRS visual acuity. Complete CNV closure was achieved in all patients at day 1. Choroidal hypoperfusion was minimal in eyes treated with a reduced fluence of 25 J/cm2. Most patients treated with 50 J/cm2 showed significant choriocapillary nonperfusion at week 1, lasting as long as 3 months. A transient PDT-induced increase in leakage area in FA at day 1 was found to be more extensive in the 50-J/cm2 group. Bolus administration of verteporfin combined with a reduced light dose achieved improved selectivity of photodynamic effects, avoiding collateral alteration of the physiologic choroid while obtaining complete CNV closure. An increased selectivity with decreased effect on the surrounding choroid should be of advantage in verteporfin monotherapy as well as in combination strategies.

Topographic Angiography and Optical Coherence Tomography: A Correlation of Imaging Characteristics

Topographic angiography (TAG) using confocal scanning laser angiography and optical coherence tomography (OCT) are new imaging modalities that have been introduced during recent years. OCT and TAG imaging were compared to specify the characteristics of each imaging modality. TAG using fluorescein angiography (FA) provides a three-dimensional profile of the vascular structures based on the analysis of a set of 32 confocal images over a depth of 4 mm. OCT provides cross-sectional images of the neurosensory retina and the retinal pigment epithelium-choriocapillary complex (RPE-CC). The authors compared and evaluated both modalities in 10 patients with predominantly classic choroidal neovascularization (CNV), 10 patients with serous pigment epithelial detachment (PED), and 10 patients with geographic RPE atrophy, all secondary to age-related macular degeneration (ARMD). In patients with classic CNV, TAG detected neovascular structures and delineated their configuration. In PEDs pooling of extravascular fluid is demonstrated, and in geographic RPE atrophy TAG showed reduced choroidal perfusion. Classic CNV was demonstrated by OCT as a hyperreflective band at the level of the RPE-CC, and PED showed a dome-shaped RPE detachment. In geographic RPE atrophy, OCT imaged loss of the RPE band and had an increased depth resolution. TAG and OCT are useful imaging modalities in the evaluation of ARMD cases. TAG visualizes the vascular configuration and dynamic perfusion and leakage changes. OCT is able to document intra-, subretinal, and sub-RPE fluid accumulation secondary to CNV. Both modalities may provide further valuable insight into ARMD pathogenesis, enhance diagnostic quality, and improve the assessment of therapeutic effects.

Acute choroidal closure caused by hemodialysis accident in an amyloidosic patient

We report the case of a 43-year-old man haemodialysed for 20 years for systemic amyloidosis who underwent an acute choroidal occlusion after a haemodialysis accident. The patient had cardiac, pulmonary, neurovegetative and renal localizations of amyloidosis. He complained during a haemodialysis session of discomfort with abdominal pain, headache, bradycardia, vomiting, confusion and blurred vision. Acute haemolytic anemia was confirmed. In the following days, eyes were red and the vision was still altered. Examination showed decreased visual acuity (VA) to 20/80 OU, low intraocular pressure (IOP), major vitritis and pigmentary alterations of the fundus with yellow retinal deposits. Fluorescein and indocyanine green angiographies showed amyloid retinal deposits, pigmentary alterations, normal retinal perfusion and massive choroidal hypoperfusion persisting in the late sequence. Steroid therapy was tried unsuccessfully. The situation slowly improved within 3 months with complete clearing of the vitreous opacities and stabilisation of the pigmentary alterations. VA progressively recovered to 20/30, 1 year after the onset of the disease, but IOP remained low and choroidal perfusion did not improve 2 years after the accident. Choroidal complications of amyloidosis have never been described so far. The acute occlusion observed here was the consequence of an intravascular haemolytic event that completed the preexisting amyloid vascular infiltration.

DECREASED ARTERIAL DYE-FILLING AND VENOUS DILATION IN THE MACULAR CHOROID ASSOCIATED WITH AGE-RELATED MACULAR DEGENERATION

To compare the angioarchitecture of choroidal arteries and veins in patients with age-related macular degeneration (AMD) to the angioarchitecture of age-matched normal subjects using indocyanine green (ICG) angiography. ICG angiography was performed in 35 consecutive AMD patients and 18 normal age-matched volunteers with a fundus ICG camera. ICG video images, including the arterial and venous phases, were quantitatively analyzed using image analyzing software. In patients with AMD, the choroidal arterioles are dilated, fewer, run a straighter course, and possess fewer bifurcations. The number of choroidal arteries and the macular fluorescent intensity in the arterial phase of choroidal filling was significantly less in patients with AMD as compared to age-matched normal controls (P = 0.008). The mean and maximum caliber of choroidal veins in the macula was dilated in AMD eyes than in age-matched normal control eyes (P < 0.001). There was no statistically significant difference in arterial dye filling or venous caliber observed in AMD eyes, with or without choroidal neovascular membrane (CNV). Choroidal arterial perfusion in the macula was significant decreased in eyes with AMD with and without CNV, and was associated with choroidal venous dilation. These observations implicate poor choroidal perfusion of the macula in the pathogenesis of AMD.

Effects of glaucoma drugs on ocular hemodynamics in normal tension glaucoma: a randomized trial comparing bimatoprost and latanoprost with dorzolamide [ISRCTN18873428

BackgroundReduced choroidal perfusion is hypothesized to play a role in the pathogenesis of normal tension glaucoma. Thus the impact of antiglaucomatous eye drops on ocular perfusion has been the focus of recent research and the subject of intensive investigations. The present study investigates whether topically applied latanoprost or bimatoprost influence ocular perfusion in patients with normal tension glaucoma and compares these effects with that changes detected after the treatment with dorzolamide.MethodsOcular hemodynamics were assessed by color Doppler imaging (CDI) shortly before and after a one-month treatment with either latanoprost, bimatoprost or dorzolamide. Primary end-points of the study were peak systolic and end-diastolic blood flow velocities in the short posterior ciliary artery (SPCA) under the new therapy. Intraocular pressure (IOP) and additional perfusion parameters in the SPCA and other retrobulbar vessels were tracked as observational parameters. n = 42 patients with normal tension glaucoma were enrolled in the study.ResultsSystolic and diastolic blood flow velocities in the SPCA showed no significant alteration after the treatment with latanoprost or bimatoprost. Dorzolamide lead to increase of peak systolic velocity. IOP was reduced by all three agents in a range reported in the literature.ConclusionTopically applied latanoprost and bimatoprost act in a hemodynamically neutral manner and have the capability to lower IOP even in patients with normal tension glaucoma and low initial IOP level. Dorzolamide accelerates blood flow in systole. None of the tested compounds has a negative impact on hemodynamics in the short posterior ciliary arteries.

Choroidal perfusion measurements made with optical coherence tomography

Choroidal perfusion measurements are complicated by the choroid's location posterior to the retina and its associated retinal blood vessels. Optical coherence tomography is a relatively new imaging technique with sufficient spatial resolution to isolate choroidal backscattering events from the posterior eye. We modified a speckle imaging algorithm to analyze sequential axial depth scans obtained from posterior rat eye to obtain an indicator of choroidal perfusion. This indicator is correlated with known changes in choroidal blood flow in response to increased intraocular pressure.

Evaluation of choroidal perfusion of the new central macular area by dilution analysis of indocyanine green angiography after macular translocation.

To evaluate the possible long-term alterations of choroidal perfusion parameters in the new central macular area after macular translocation surgery. Eleven subjects with subfoveal neovascular membrane secondary to age-related macular degeneration or degenerative myopia underwent indocyanine green angiography by using a scanning laser ophthalmoscope before and after macular translocation (mean, 10 months after surgery). Fluorescence intensity of the new central macular area over time was evaluated. Parameters derived from the intensity curves included 10% filling time, ascending slope, and maximal intensity of brightness. The 10% filling time reflects the rapidity of the early choroidal filling phase, whereas the slope of the filling of the curve shows the speed of blood entrance into the choroid. Maximal intensity of brightness indicates vascular density of the area. No statistical difference was encountered before or after macular translocation in 10% filling time (14.25 +/- 2.09 seconds versus 16.20 +/- 2.95 seconds), slope of the ascending portion of the curve (0.12 +/- 0.04 versus 0.11 +/- 0.04), and maximal intensity of brightness (0.89 +/- 0.09 versus 0.88 +/- 0.07) in the new central macular area. The rotational degree of the retina against the retinal pigment epithelium did not show any significant correlation with 10% filling time, slope, or maximal intensity of brightness. Choroidal perfusion parameters in the new foveal region do not change after macular translocation surgery.

Ophthalmic fundus imaging: today and beyond

PurposeTo review and update techniques of posterior segment ophthalmic fundus imaging. DesignLiterature review and collective experience of the authors. MethodsThis perspective includes sections on digital imaging, fundus autofluorescence, ultrasonography, angiography, and optical coherence tomography (OCT) -ophthalmoscopy written by leading clinicians and researchers in these areas. ResultsDigital angiography has become the new standard in the ophthalmic community based upon improved technology which has enhanced resolution, processing time, and ease of image duplication, manipulation, and transmission. A relatively new imaging technique, fundus autofluorescence, highlights lipofuscin deposits and improves our understanding of the metabolic status of the retinal pigment epithelium. Diagnostic ultrasonography continues to be a major adjunct to ocular evaluation where advances now allow for exceptional versatility and portability. High speed angiographic techniques provide detailed visualization of choroidal perfusion which improves our understanding of both normal and pathologic vascular phenomenon. Advances in high-resolution OCT currently under development promise an even more detailed fundus representation. The integration of the scanning laser ophthalmoscope and OCT has produced a dynamic new instrument, the OCT ophthalmoscope, which simultaneously images the fundus in numerous ways with point to point correlation. ConclusionsOphthalmic imaging technology has revolutionized fundus examination. Currently available systems have contributed significantly to our understanding of the pathophysiology and treatment of various retinal diseases. Future advances promise near histologic resolution of retinal structures as well as real-time image manipulation and instantaneous transmission world-wide.

Laser-induced macular holes demonstrate impaired choroidal perfusion.

To evaluate choroidal perfusion following creation of a laser-induced macular hole in a nonhuman primate model. Six rhesus monkeys underwent macular exposures delivered by a Q-switched Nd:YAG laser. The lesions were evaluated with fluorescein angiography and indocyanine green angiography using scanning laser ophthalmoscopy. Each lesion produced vitreous hemorrhage and progressed to a full-thickness macular hole. Indocyanine green angiography revealed no perfusion of the choriocapillaris beneath the lesion centers. Fluorescein angiography demonstrated mild enlargement of the foveal avascular zone due to loss of perifoveal capillaries. Histopathologic evaluation showed replacement of the choriocapillaris with fibroblasts and connective tissue. Nd:YAG laser-induced macular holes result in long-term impairment of choroidal perfusion at the base of the hole due to choroidal scarring and obliteration of the choriocapillaris. Evaluation of choroidal perfusion may be useful in assessment of laser-injured patients. Impairment in choroidal perfusion may have functional implications for surviving photoreceptors.

Changes in the choroidal circulation of rabbit following RPE removal

To examine the effects of surgical removal of the retinal pigment epithelium (RPE) on the choroidal circulation of the rabbit. The retina and choroid were examined by biomicroscopy, scanning laser ophthalmoscopy, fluorescein and indocyanine green angiography and histology at various times after the surgical removal of the RPE by gentle aspiration following a prior local vitrectomy and bleb detachment. Comparison was made between small and large areas of RPE removal, or only slight pressure to the retina without removal of RPE. Removal of the RPE layer causes transient leakage of vascular fluid into the subretinal space for at least a week after surgery and loss of perfusion in the underlying choroidal vessels and choriocapillaris at the débridement site. This reduction in local choroidal blood flow can occur within 15 min after RPE débridement and can be transient or permanent. Histology indicates that permanent changes are due to fibroblastic infiltration that compresses the choroidal vessels. Permanent changes tend to occur after removal of relatively large areas of RPE. The removal of small areas of RPE or slight pressure on the retina causes a transient loss of local choroidal perfusion, and fibroblastic infiltration into the choroid does not occur. Removal of the RPE causes changes throughout the underlying choroid. It reduces the circulation in the large choroidal vessels as well as the choriocapillaris. If large areas of RPE are removed, this choroidal non-perfusion can be permanent due to fibroblastic infiltration. Small areas of RPE removal or slight pressure on the retina lead to only transient reduction of the choroidal flow. The rapidity with which the choroidal blood flow can be reduced implies a reflex mechanism that responds to sudden RPE pressure and/or trauma. These changes are best observed with ICG angiography.

Topical fundus pulsation measurement in patients with active central serous chorioretinopathy.

To determine regional pulsatile choroidal blood flow using laser interferometry in patients with active central serous chorioretinopathy (CSC). The study compared an equally sized age-, sex-, and refractive error-matched control group of healthy volunteers obtained from the Department of Clinical Pharmacology with 18 consecutive patients who had newly diagnosed active, unilateral CSC obtained from the University of Vienna Eye Clinic, Vienna, Austria. Regional fundus pulsation amplitude as assessed using laser interferometry. The median age of the patients was 40 years; the male-female ratio was 16:2. Foveal fundus pulsation amplitude was significantly higher in eyes with CSC (mean [SD], 5.5 [1.7] micro m) than in the eyes of the control subjects (4.1 [1.1] micro m; P =.005). In addition, eyes with CSC had a significantly higher variability in fundus pulsation amplitude (mean [SD], 48% [20%]) assessed at different fundus locations around the leak than the controls did (20% [9%]; P<.001). To our knowledge, this is the first study that measures topical fundus pulsations in patients who have active, unilateral CSC. These data indicate a generally increased foveal pulsatile choroidal blood flow and an abnormal distribution of fundus pulsation amplitude in the area close to the leak. Whether these findings reinforce the concept that choroidal perfusion abnormalities play a role in the pathogenesis of CSC remains to be established.