CHOROIDAL VASCULAR OCCLUSION IN INTERNAL CAROTID ARTERY OBSTRUCTION

Swept-source optical coherence tomography early findings in patients with carotid artery disease

PURPOSE

Ocular ischemic syndrome can be the first and only hint of life-threatening carotid artery disease. The early recognition of carotid stenosis-related retinal signs, as well as the comprehension of the pathophysiology behind retinal changes could become relevant for physicians to predict the risk of stroke. The aim of this study is to assess the carotid artery disease-induced early structural retinochoroidal changes by means of swept-source optical coherence tomography (SS-OCT).

METHODS

A prospective observational study was conducted in 72 eyes with carotid stenosis. According to the degree of stenosis, the participants were divided into a normal group (34 eyes), a mild-moderate stenosis group (22 eyes), a severe stenosis group (16 eyes). SS-OCT and OCTA were performed to scan macular fovea. Central macular thickness (CMT), subfoveal choroidal thickness (SCT) and foveal avascular zona (FAZ) area were the major measurements for our study.

RESULTS

CMT was significantly thicker in group 3 when compared to group 2 and 1. SCT was significantly thinner in group 3 vs group 1, being thicker in group 2 when compared to group 1. No significant differences were obtained when comparing FAZ in the superficial and middle capillary plexus although it was significant when comparing the FAZ in the deep capillary plexus between group 1 and 3.

CONCLUSION

internal carotid artery stenosis greater than 70% leads to a significant increase in CMT and a decrease in SCT prior the development of clinical findings of ocular ischemia syndrome.

Atypical chorioretinal lesions in Siberian Husky dogs with primary angle-closure glaucoma: a case series

BACKGROUND

A number of etiologies for different canine chorioretinal lesions have been proved or suggested but some fundic lesions remain unclear in terms of an etiologic diagnosis, treatment options and prognosis. The purpose of this case series is to describe atypical chorioretinal lesions observed in dogs with primary angle-closure glaucoma (PACG).

CASE PRESENTATION

Two spayed-female Siberian Huskies (3- and 4-year-old) and one Siberian Husky/Australian Shepherd mixed breed dog (11-month-old) that had multifocal depigmented retinal lesions and PACG were included.

PROCEDURES

Ophthalmic examination, gross, and histopathologic examination findings are described. One of the dogs underwent further clinical diagnostics. Advanced clinical diagnostics on the fellow, presumed to be non-glaucomatous eye of a dog revealed: pectinate ligament dysplasia by gonioscopy, retinal thinning in the depigmented area and wedge shaped retinal thinning with delayed choroidal vascular perfusion by optical coherence tomography, confocal scanning laser ophthalmoscopy, fluorescein and indocyanine green angiography. Quantifiable maze testing for the same eye revealed mild nyctalopia but the full-field electroretinogram showed no generalized decrease of retinal function. Genetic testing for mutations within the retinitis pigmentosa GTPase regulator gene causing X-linked progressive retinal atrophy in Siberian Huskies was negative. Histopathologic evaluations on enucleated eyes in two dogs confirmed goniodysgenesis, PACG with optic nerve head cupping, and diffuse inner retinal atrophy. In addition, segmental profound retinal atrophy, loss of retinal pigment epithelium, and adhesion of the retina to Bruch's membrane was observed and coincided with multifocal depigmented lesions noted on fundic examination.

CONCLUSIONS

To our knowledge, this is the first case series with clinical and histopathologic data of chorioretinal lesions, most likely caused by severely impaired choroidal perfusion. Further studies are warranted to elucidate the etiology and pathophysiology, including its possible association with PACG.

Relationship between internal carotid artery stenosis grade and optic nerve sheath diameter measured by transorbital ultrasonography

PURPOSE

To assess the consequence of the presence, grade, and asymmetry of carotid artery stenoses on the optic nerve sheath diameter (ONSD) measured by ultrasonography.

METHODS

ONSD was measured with B-mode ultrasonography in 129 patients referred for duplex and color Doppler imaging of the carotid arteries. Internal carotid artery stenosis was graded on the basis of peak systolic flow velocity.

RESULTS

The mean ONSD was 3.04 ± 0.38 mm in the patients without or with <50% internal carotid artery stenosis and 2.46 ± 0.35 mm in those with >70% stenosis. There was an average difference of 0.58 mm between the ONSD of the patients with <50% and the patients with >70% stenosis.

CONCLUSION

ONSD is lower in patients with carotid artery stenosis. Carotid arteries should be investigated, especially in patients with cardiovascular risk factors or diseases, before interpreting ONSD values.

Vascular emergencies in neuro-ophthalmology

The cerebral vascularization is assured by the 2 internal carotids and 2 vertebral arteries, and the Willis circle.

Carotid artery obstruction is the most common abnormality associated with ocular ischemic syndrome. Obstruction may be due to atheromatous plaque, external compression, arteritis, or dissection of the artery. An atheromatous lesion of the carotid artery is the most frequent lesion responsible for ocular ischemic syndrome. The signs and symptoms of ocular ischemic syndrome are associated with severe hypoperfusion of the eye. Inflammatory lesions of the carotid artery are responsible for decreased flow in the carotid system. Other vascular emergencies are carotid artery dissection, Horton arteritis, aneurysms and carotid-cavernous fistula.

The most common ocular signs and symptoms are transient monocular blindness, persistent monocular blindness, ocular ischemia, Claude Bernard Horner syndrome and oculomotor palsies.

The carotid pathology can be a life-threatening pathology and it is important to recognize all these signs and symptoms. A multi-specialty approach will prevent misdiagnosis and lead to a better patient management.

Abbreviations: OIS = ocular ischemic syndrome, TMB = transient monocular blindness, TIA = transient ischemic attack, ESR = erythrocyte sedimentation rate, CRP = C reactive protein, NVE = neovascularization elsewhere in the retina, NVD = neovascularization on the disc, AION A = anterior ischemic arteritic optic neuropathy, CBH = Claude Bernard Horner syndrome, MRI = magnetic resonance imaging

Investigation of macular and optic nerve head structural changes using spectral domain optical coherence tomography in internal carotid artery stenosis

PURPOSE

To demonstrate differences in optic nerve head (ONH), retinal nerve fiber layer (RNFL), and macular thickness in patients with internal carotid artery (ICA) stenosis using spectral domain optical coherence tomography (SD-OCT).

METHODS

A case-controlled study was conducted in 31 patients with a diagnosis of unilateral ICA stenosis (the percentage of stenosis was between 65 and 85%), and 53 age- and sex-matched healthy subjects (control group) from March 2016 to April 2018. The ONH parameters, RNFL, and macular thicknesses in the nine macular quadrants according to the Early Treatment Diabetic Retinopathy Study (ETDRS) were measured using SD-OCT.

RESULTS

The average macular thickness and outer macular quadrants measurements were lower in the ICA stenosis group (P < 0.05). The thickness of the fovea and inner macular quadrants was similar in healthy and patient eyes. Similarly, the ONH and RNFL profiles based on SD-OCT parameters were similar between the groups. There was a negative weak correlation between mean macular and RNFL thicknesses and the duration and percentage of ICA stenosis.

CONCLUSION

The average macular thickness and measurements of outer macular quadrants in the ICA stenosis group were lower than in the control group. Macular changes may occur before symptomatic ocular ischemic syndrome (OIS). SD-OCT macular measurements may be beneficial in the early detection of OIS due to ICA stenosis.

Evaluation of Peripapillary and Subfoveal Choroid Thickness in Asymptomatic Carotid Artery Stenosis

Objective

In this study, it aims to investigate the effect of asymptomatic carotid artery stenosis on peripapillary and subfoveal choroid thickness using enhanced depth imaging optical coherence tomography.

Patients and Methods

While investigating for coronary artery disease, 76 patients with asymptomatic carotid artery stenosis and 35 patients with normal carotid artery (total = 111) were evaluated. Patients according to the degree of stenosis were divided into four categories as non-stenosis (n = 35), mild (n = 26), moderate (n = 27) and severe stenosis (n = 23). Subfoveal and peripapillary choroid thickness, ocular perfusion and intraocular pressures of all patients were measured using a Fourier-domain optical coherence tomography after general ophthalmological examination. In addition, hypertension, hyperlipidemia, and whether there is a relationship between smoking status and choroid thickness was compared.

Results

As the degree of carotid artery stenosis increased, subfoveal and peripapillary choroidal thickness decreased significantly. However, no changes were detected in ocular perfusion and intraocular pressure values (p=0.935, p=0.519). Decrease in peripapillary and subfoveal choroid thickness values was found to be particularly between the group with severe stenosis and the group with control and mild stenosis (p = 0.003, p = 0.001). In addition, as the degree of carotid stenosis increased in patients with hypertension and smoking, peripapillary choroid thickness was found to be thinner (p=0.003).

Conclusion

We believe that the possibility of carotid artery stenosis should be considered in cases with decreased choroid thickness. In addition, we think that even if it is asymptomatic, in cases with severe carotid stenosis, in the presence of choroidal thinning, a chance of surgical intervention should be given to the stenosis.

Time Course in Ocular Blood Flow and Pulse Waveform in a Case of Ocular Ischemic Syndrome with Intraocular Pressure Fluctuation

We report on a 70-year-old Japanese man with complaints of worsening left visual acuity who was diagnosed with ocular ischemic syndrome (OIS) associated with internal carotid artery (ICA) stenosis. A gonioscopy examination showed rubeosis iridis and elevated intraocular pressure (IOP) in the left eye (50 mmHg) at the baseline visit. The optic nerve head (ONH) and choroidal blood flow measured by laser speckle flowgraphy (LSFG) was impaired in the left eye compared with that in the right eye. Additionally, the blowout score (BOS), which indicates the variation of the mean blur rate (MBR) during systolic and diastolic periods, was decreased in the left eye. After treatment with an injection of bevacizumab and administration of Rho-associated kinase-inhibitor ripasudil eye drops, both ocular blood flow and BOS in each vascular bed gradually increased along with IOP reduction. The visual acuity also improved. The current case demonstrated increased blood flow and decreased fluctuation of blood flow in the ONH and choroid before and after the treatment in OIS with rubeosis iridis. The LSFG technique is useful to non-invasively assess the ocular circulation and pulse waveform in OIS.

Choroidal thickness in patients with cardiovascular disease: A review

The choroid is a vascular network that supplies the bulk of the retina's oxygen and nutrient supply. Prior studies have associated changes in the thickness of the choroid with the presence of various cardiovascular diseases. This is the first review that summarizes current knowledge on the relationship between choroidal thickness and cardiovascular diseases while highlighting important findings. Acute hypertension increases choroidal thickness. Chronic hypertension and heart failure may decrease choroidal thickness, but controversy exists. Both coronary artery disease and carotid artery stenosis result in decreased choroidal thickness and blood flow. Carotid endarterectomy may reverse these changes. Choroidal thickening in early stages of carotid stenosis may arise from mechanisms compensating for ischemia. Hyperlipidemia is linked to choroidal thickening, while caffeine intake is linked to choroidal thinning. The effects of smoking and exercise are mixed. Changes in choroidal thickness have been linked to cardiovascular disease. Clarity regarding these changes could lead to the use of choroidal thickness changes as a noninvasive screening or prognostic test for pathological cardiovascular changes. Future studies should also investigate the effect of cardiovascular disease treatments on the choroid.

Structural Analysis of the Retina and Choroid before and after Carotid Artery Surgery

Purpose: To evaluate retinal and choroidal changes in patients with internal carotid artery stenosis who had undergone carotid artery stenting or endarterectomy.Methods: The study included 43 patients with internal carotid artery (ICA) stenosis that required stenting or endarterectomy and 40 healthy controls. Patients were divided into two groups according to the degree of stenosis evaluated by magnetic resonance angiography. Group 1 consisted of patients having ICA stenosis of 50 to 70%, and Group 2 has more than 70%. Enhanced depth imaging optical coherence tomography (EDI-OCT) was used to measure the retinal thickness (RT) and choroidal thickness (CT) in all subjects before surgery and at 1, 3, and 6 months after surgery.Results: Subfoveal and parafoveal CT were significantly lower in patients with ICA stenosis than the control group (p < .05, respectively). Patients with 50-70% stenosis had a significant increase in the CT at 1, 3, and 6 months after ICA stenting or endarterectomy (p < .05). Patients with >%70 stenosis did not have a significant increase in the CT at any time after ICA stenting or endarterectomy. Retinal thickness was not statistically different between the patients with ICA stenosis and the control subjects, and RT showed no significant change in patients with ICA stenosis before and after the surgery.Conclusion: Choroidal thickness was significantly thinner in patients with internal carotid artery stenosis. ICA stenting provided a recovery in the choroidal thickness in patients with moderate to advanced stenosis.

Spectral Domain Optical Coherence Tomography Findings in Carotid Artery Disease

Objectives:

To evaluate the effect of carotid artery disease on retinal morphology by means of spectral domain optical coherence tomography (SD-OCT).

Materials and Methods:

We examined 23 eyes with internal carotid artery (ICA) stenosis and 24 age- and gender-matched healthy eyes as a control group in this prospective, case-control study. Compherensive ophthalmic examination and SD-OCT scan were performed to all the patients. The average RNFL and macular thicknesses (MT) in the nine macular ETDRS areas were the major OCT measurements for our study.

Results:

Although all of the average RNFL and MT measurements were lower in the ICA stenosis group, only the total MT and outer ETDRS area (temporal/superior/nasal/inferior outer macula) values were found to be significantly thinner compared to the control group (p=0.004, p=0.009, p<0.001, p=0.002, and p=0.001, respectively).

Conclusion:

In addition to our knowledge about the effects of ICA stenosis on the retino-choroidal circulation, we found that OCT measurements may be beneficial in the early detection of ocular damage due to ICA stenosis.

Multimodality Imaging Assessment of Ocular Ischemic Syndrome

Objectives

To assess the underlying mechanisms of OIS and confirm the haemodynamic and retinal structure changes of early OIS.

Methods

An observational cross-sectional study was conducted of 60 internal carotid artery (ICA) stenosis patients, and they were divided into OIS and control group. Colour doppler imaging, optical coherence tomography, and fundus fluorescein angiography were performed.

Results

The middle cerebral artery (MCA) stenosis differs significantly between the two groups. More OIS patients had new collateral patency of posterior communicating artery (PCoA) and retrograde flow via the ophthalmic artery (OA) (p < 0.001). The peak systolic velocity (PSV) in central retinal artery (CRA) and choroidal thickness (CT) was significantly reduced in OIS patients (p = 0.001 and p < 0.001). The arm-retina time (ART) and the retinal arteriovenous passage time (AVP) were prolonged in OIS patients (p < 0.001 and p = 0.001). CT, ART, and PSV of the CRA showed high sensitivity, while ART and ICA stenosis grade showed high specificity for the diagnosis of OIS according to ROC curve.

Conclusions

Patients who suffered from severe ipsilateral ICA stenosis, new collateral patency of PCoAs, and MCA stenosis may be more susceptible to OIS. The most sensitive sign is PSV of CRA and CT, and the most specific sign is ART.

Association between Asymptomatic Unilateral Internal Carotid Artery Stenosis and Electrophysiological Function of the Retina and Optic Nerve

Purpose. This study was designed to assess retinal and optic nerve bioelectrical function in patients with unilateral asymptomatic but hemodynamically significant internal carotid artery stenosis (ICAS). Methods. Forty-two subjects with a diagnosis of unilateral ICAS and 34 controls were analyzed. Full-field electroretinogram (ERG), pattern electroretinogram (PERG), and pattern visual-evoked potentials, as well as optical coherence tomography and ophthalmological examination, were performed. Data analysis included eyes ipsilateral to ICAS (EIS) and eyes contralateral to ICAS (ECS). Results. Intraocular pressure was significantly decreased in EIS and ECS compared to that in the controls. In the macula, both the cube average thickness and cube volume values were significantly reduced both in EIS and ECS compared to those in the controls. Similarly, PERG P50 and N95 wave amplitudes were significantly smaller in EIS and ECS compared to those in the controls. The ERG rod b-wave and rod-cone a-wave amplitudes were decreased, and implicit times were significantly prolonged, whereas the OP wave index was reduced in EIS compared to that in the controls. No differences in IOP, OCT, or ERG and PERG parameters were identified between EIS and ECS. Conclusions. Our study demonstrated that retinal bioelectrical function is negatively affected by ICAS despite the absence of objective clinical signs and symptoms of ocular ischemia.

Evaluation of Fundus Blood Flow in Normal Individuals and Patients with Internal Carotid Artery Obstruction Using Laser Speckle Flowgraphy

Purpose

We investigated whether laser speckle flowgraphy (LSFG) results are comparable in both eyes and whether it is useful in the diagnosis of disparity in ocular ischemic syndrome (OIS) patients.

Methods

We compared the mean blur rate (MBR) value for various fundus regions in both eyes of 41 healthy subjects and 15 internal carotid artery occlusion (ICAO) cases. We calculated the standard value of the Laterality Index (LI), which was the MBR comparison of both eyes in each of the regions, in the control subjects. We then investigated the correlation between both eyes for the LIs in the entire fundus, the degree of ICAO and visual function.

Results

The disparity of the LIs in both eyes was least in the entire area of the fundus in control subjects and there was a significant correlation between both eyes of the 41 healthy individuals (P = 0.019). Significant correlations were found for the LI, visual acuity and degree of ICAO. The specificity and sensitivity of LI in the entire area was 93.8% and 100%, respectively.

Conclusions

LSFG revealed normal individuals have symmetrical fundus blood flow. LSFG could detect OIS and might be a useful tool for detecting disparities in fundus blood flow.

A quantitative evaluation of the posterior segment of the eye using spectral-domain optical coherence tomography in carotid artery stenosis: a pilot study

BACKGROUND AND OBJECTIVE

To evaluate the posterior segment of the eye using spectral-domain optical coherence tomography (SD-OCT) in patients with internal carotid artery (ICA) stenosis.

PATIENTS AND METHODS

Prospective study enrolling 25 patients with ICA stenosis (study group) and 25 age- and gender-matched healthy individuals (control group). Macular choroidal thickness (CT) was measured at the fovea; other CT measurements were taken 1,000 µm away from the fovea in the nasal, temporal, superior, and inferior regions by enhanced-depth imaging OCT (EDI-OCT). The thicknesses of the retinal nerve fiber layer (RNFL), macula, and ganglion cell complex (GCC) were measured with SD-OCT. Correlations between the CT values and the degree of ICA stenosis were also evaluated.

RESULTS

Mean macular CT values in the study group were significantly thinner than those of the control groups for all quadrants (P < .05). There was no significant correlation between the degree of ICA stenosis and the CT values. Moreover, the mean thicknesses of the RNFL, macula, and GCC did not differ between the two groups.

CONCLUSION

The results suggest that CT decreases in patients with ICA stenosis compared with age-matched healthy individuals, whereas the RNFL, macular, and GCC thicknesses are comparable.