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Ocular blood flow in course of glaucoma 

Study explores influence of ocular blood flow in course of glaucoma 

New techniques shed light on roles of blood, perfusion pressure in ocular blood flow

 

Many other factors, including demographic influences and individual susceptibilities, also make it challenging to study relationships between ocular blood flow and glaucoma.

To overcome the multiple confounders, Dr. Harris and colleagues have proposed using a mathematical model to leverage the analogy between blood flow in a network of vessels and current flow in a circuit.

The model calculates ocular blood flow taking into account vascular regulation, cerebrospinal fluid pressure, blood pressure, venous blood pressure, and IOP.

He illustrated its performance by describing its application for determining how changes in IOP and blood pressure affect retinal blood flow. Inputs for the model included three theoretical patients with different blood pressures (low, normal, and high) and IOP values ranging from 15 to 45 mm Hg.

According to the model, retinal blood flow was unchanged for IOP values < 26 mm Hg in the theoretical patients with high or normal blood pressure.

The plateau was explained by autoregulation. However, retinal blood flow continued to increase with decreasing IOP in the patient with low blood pressure.

The calculations also showed that when IOP was > 36 mm Hg, the predicted decrease in retinal blood flow decreased at a steeper slope compared with lower IOP levels as a result of partial venous collapse.

The venous collapse started earlier (at a lower IOP) in the theoretical patient with low blood pressure compared with the normal and high blood pressure patients.

“These data explain the findings of population-based studies showing that decreased blood pressure and decreased perfusion pressure are independent risk factors for glaucoma,” Dr. Harris said.

 

Alon Harris, PhD

E: alharris@indiana.edu

This article was adapted from a presentation delivered by Dr. Harris at Glaucoma Subspecialty Day preceeding the 2016 American Academy of Ophthalmology meeting. He has no relevant financial interests to disclose.

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Images in Philadelphia Telemedicine Glaucoma Detection and Follow-up Study: Methods and Screening Results - American Journal of Ophthalmology

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Images in Philadelphia Telemedicine Glaucoma Detection and Follow-up Study: Methods and Screening Results - American Journal of Ophthalmology

The results of this project will provide important information regarding the value of using telemedicine for detecting, following, and treating participants with glaucoma or glaucoma suspect in an urban setting. This project clearly demonstrates how practice-based telemedicine screening can improve access to and detection of glaucoma and other eye diseases in high-risk individuals.

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Epidemiology of discordance between symptoms and signs of dry eye | British Journal of Ophthalmology

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Epidemiology of discordance between symptoms and signs of dry eye | British Journal of Ophthalmology

Conclusions The present study provides evidence that the degree of discordance between DE symptom report and measurable signs of ocular surface disease is associated with comorbidities related to clinical pain and to hyperalgesia as demonstrated with QST. Understanding the epidemiology of DE discordance can aid in interpreting the DE exam and individualising treatment.

British Journal of Ophthalmology  Published Online First: 18 August 2017. doi: 10.1136/bjophthalmol-2017-310633

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The Charles Bonnet Syndrome in Patients With Neovascular Age-Related Macular Degeneration: Association With Proton Pump Inhibitors | IOVS | ARVO Journals

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The Charles Bonnet Syndrome in Patients With Neovascular Age-Related Macular Degeneration: Association With Proton Pump Inhibitors | IOVS | ARVO Journals

The prevalence of CBS in neovascular-AMD patients is high and mainly affects older individuals with poor visual acuity. PPIs seem to increase the risk of development of hallucinations independently of the degree of visual loss.

Investigative Ophthalmology & Visual Science August 2017, Vol.58, 4138-4142. doi:10.1167/iovs.16-21270

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Oculo-Visual Dysfunction in Parkinson's Disease

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Oculo-Visual Dysfunction in Parkinson's Disease

Oculo-Visual Dysfunction in Parkinson's Disease.

 J Parkinsons Dis. 2015;5(4):715-26. doi: 10.3233/JPD-150686

Armstrong RA.

Abstract

This review describes the oculo-visual problems likely to be encountered in Parkinson's disease (PD) with special reference to three questions: (1) are there visual symptoms characteristic of the prodromal phase of PD, (2) is PD dementia associated with specific visual changes, and (3) can visual symptoms help in the differential diagnosis of the parkinsonian syndromes, viz. PD, progressive supranuclear palsy (PSP), dementia with Lewy bodies (DLB), multiple system atrophy (MSA), and corticobasal degeneration (CBD)? Oculo-visual dysfunction in PD can involve visual acuity, dynamic contrast sensitivity, colour discrimination, pupil reactivity, eye movement, motion perception, and visual processing speeds. In addition, disturbance of visuo-spatial orientation, facial recognition problems, and chronic visual hallucinations may be present. Prodromal features of PD may include autonomic system dysfunction potentially affecting pupil reactivity, abnormal colour vision, abnormal stereopsis associated with postural instability, defects in smooth pursuit eye movements, and deficits in visuo-motor adaptation, especially when accompanied by idiopathic rapid eye movement (REM) sleep behaviour disorder. PD dementia is associated with the exacerbation of many oculo-visual problems but those involving eye movements, visuo-spatial function, and visual hallucinations are most characteristic. Useful diagnostic features in differentiating the parkinsonian symptoms are the presence of visual hallucinations, visuo-spatial problems, and variation in saccadic eye movement dysfunction.

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Effects of Pentoxifylline on Blood Flow in Patients with Non-Arteritic Ischemic Optic Neuropathy | IOVS | ARVO Journals

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Effects of Pentoxifylline on Blood Flow in Patients with Non-Arteritic Ischemic Optic Neuropathy | IOVS | ARVO Journals

Jesse GaleEdward Rickie ChuStarleen Elizabeth FrousiakisSowmya SrinivasRustum KaranjiaOu TanDavid HuangSrinivas R SaddaAlfredo A Sadun

Purpose: To determine whether Doppler OCT can be used to measure retinal arteriole-derived ocular blood flow in patients with non-arteritic ischemic optic neuropathy (NAION), who are treated with pentoxifylline.

Methods: Seven affected eyes and two fellow eyes from five patients with NAION (one eye not measureable), all receiving pentoxifylline (a xanthine derivative that affects erythrocyte rheology), were examined with Doppler OCT. This group was compared to our previously published group of untreated NAION eyes (N=8) (Wang et al.; IOVS 52(2): 840, 2011) and normal eyes (n=10), (Wang, et al.; Br J Ophthalmol. May; 93(5): 634, 2009). Doppler OCT was performed using high-resolution Fourier domain-OCT scans and post-acquisition blood flow calculations, using our previously published technique (Wang et al., 2009).

Results: The average blood flow in pentoxifylline-treated eyes with NAION was 29 µl/min, which was comparable to 28 μL/min in the previous untreated cohort of NAION eyes (Wang et al.; IOVS 52(2): 840, 2011). The average blood flow in the fellow eye of treated patients with unilateral NAION was 52 µl/min, which was a small increase from somewhat younger control eyes in the previous cohort (45 μL/min; Wang et al., 2009).

Conclusions: Doppler OCT may be promising as a technique for comparing treated to untreated eyes. When compared to untreated normative data, pentoxifylline was associated with a small increase in the retinal blood flow of fellow eyes in patients with unilateral NAION. Pentoxyfylline did not increase blood flow in affected eyes. Further data collection is ongoing to permit a statistical analysis.

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Visual outcome of mega-dose intravenous corticosteroid treatment in non-arteritic anterior ischemic optic neuropathy – retrospective analysis

In summary, our data, with the major limitations stated above, does not suggest the superiority of IV steroid treatment over no treatment. As intravitreal corticosteroid treatment for NAION is still anecdotal [28,29], any steroid protocol for NAION patients should be used judicially. In our center, based on our experience, we chose to abandon the use of IV corticosteroids for NAION patients until a randomized control trial will prove the benefit of such treatment.

 

Kinori, Michael et al. “Visual Outcome of Mega-Dose Intravenous Corticosteroid Treatment in Non-Arteritic Anterior Ischemic Optic Neuropathy – Retrospective Analysis.” BMC Ophthalmology 14 (2014): 62. PMC. Web. 7 Sept. 2017.

 

Background

To date, non arteritic anterior ischemic optic neuropathy (NAION) is still incurable. We wish to evaluate the effect of intravenous (IV) corticosteroids on the visual outcome of NAION patients.

Methods

Visual parameters were retrospectively compared between NAION patients treated with IV corticosteroids and untreated NAION patients (control). Visual acuity (VA) and Humphrey automated static perimetry visual field (VF) defects of the affected eye were compared between groups at baseline, 1, 3, 6 months, and end of follow-up visits. The VF analysis consisted of number of quadrant involvements and mean deviation (MD).

Results

Each group comprised 23 patients (24 eyes). Mean initial VA was similar in the control and treatment groups (p = 0.8). VA at end of follow-up did not improve in either groups (p = 0.8 treated group, p = 0.1 control group). No improvement and no difference in VF defects were found by either quadrant analysis (p = 0.1 treated group, p = 0.5 control group) or MD analysis (p = 0.2, treated group, p = 0.9 control group). VA and VF parameters tended to be worse in the treated group, although without statistical significance.

Conclusions

Our results suggest that IV corticosteroids may not improve the visual outcome of NAION patients. Since intravenous corticosteroids could potentially cause serious adverse effects, this treatment for NAION is questionable.

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Eye & Vision Issues | American Parkinson Disease Assoc.

Excellent overview of vision related issues in patients with Parkinson's disease. 

Great quote: As physicians, we always have to be aware of our patients’ medications— their dosages, effects and side effects. A good history of medications is paramount. It is important to know how the person’s symptoms are affected by the medication dosages and by their schedule. 

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New Dry Eye Treatment is a Tear-Jerker - American Academy of Ophthalmology

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New Dry Eye Treatment is a Tear-Jerker - American Academy of Ophthalmology

Early signs of age-related eye diseases, including cataractglaucomadiabetic retinopathy and age-related macular degeneration can begin in midlife but often do not noticeably affect the vision until later. So it’s important to get a baseline comprehensive eye exam at age 40, even for people who have no symptoms or known risk factors. Your ophthalmologist will recommend follow-up exams based on your family history and the results of the baseline exam.

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Vision Screening Recommendations for Adults 40 to 60 - American Academy of Ophthalmology

Early signs of age-related eye diseases, including cataractglaucomadiabetic retinopathy and age-related macular degeneration can begin in midlife but often do not noticeably affect the vision until later. So it’s important to get a baseline comprehensive eye exam at age 40, even for people who have no symptoms or known risk factors. Your ophthalmologist will recommend follow-up exams based on your family history and the results of the baseline exam.

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Tips for Eye Health in Adults 40 to 60 - American Academy of Ophthalmology

Women’s Higher Risk for Some Eye Diseases

Women are more likely than men to have glaucoma and women are also more likely to be visually impaired or blind due to glaucoma. Also, women are 24 percent less likely to be treated for glaucoma. Cataract is somewhat more common in women, as well. Women should be sure to follow the Academy’s screening guidelines and adhere to their ophthalmologist’s follow-up appointment recommendations and treatment plans.

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Glaucoma Today - Pitfalls in Optical Coherence Tomography Imaging

AT A GLANCE

• Clinicians need to confirm a few rules of accurate optical coherence tomography imaging before accepting the results: signal strength, motion artifact, and proper acquisition of the image.

• When assessing progression, physicians must determine whether or not changes are clinically significant and, if so, whether they are a result of glaucoma or something else.

 

Assessing progression presents different challenges. The software must be capable of aligning to the baseline or previous image acquired in terms of location as well as angulation, because a small but different tilt of the head can result in erroneous interpretation. The physician must also determine if the change detected by the machine is clinically significant (greater than 2 standard deviations of the measurement reproducibility2). When reviewing macular measurements, clinicians must consider whether a change is a result of glaucoma, release of the posterior vitreous attachments to the RNFL, or improvement of overall blood sugar control (Figure 2). Moreover, in the presence of uveitis, coexisting RNFL edema and subclinical macular edema can result in erroneous interpretation of normal-appearing thickness.3,4 Upon subsequent resolution of such edema (with uveitis treatment), the thickness of these layers can dramatically decrease once again, giving an erroneous interpretation of glaucomatous progression.

Cystic spaces in the RNFL or subretinal space in the peripapillary region in myopia as well as cystic changes in the outer plexiform layer in rapidly advancing glaucoma can also confound interpretation.4 Masqueraders of glaucoma such as neurosyphilis, optic disc drusen, ischemic optic neuropathy, hemianopia, and optic neuritis present another set of challenges to the assessment of OCT results (Figure 3).5

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