A Pilot Study Assessing Retinal Blood Flow Dysregulation in Glaucoma Using Erythrocyte Mediated Velocimetry.

Purpose: The purpose of this study was to compare autoregulation of retinal arteriolar and venular blood flow in patients with glaucoma, glaucoma suspect participants, and control participants using erythrocyte mediated velocimetry. Methods: This prospective cohort pilot study included 7 eyes of 5 participants with glaucoma, 15 eyes of 8 glaucoma suspect participants, and 11 eyes of 6 control participants. Mean erythrocyte velocity in retinal arterioles and venules was measured using erythrocyte mediated velocimetry at room air and after oxygen supplementation. Change in erythrocyte velocity was compared among all groups using generalized estimating equations. Results: In total, 64 vessels (18 with glaucoma, 31 that were glaucoma suspect, and 15 controls) of 33 eyes of 19 participants were analyzed. There was no significant difference in baseline velocities in arterioles or venules among the three groups. With induction of hyperoxia, mean arterial erythrocyte velocity decreased in glaucoma (-7.2 ± 13.7%), which differed from controls and glaucoma suspects where erythrocyte velocity increased with hyperoxia by 4.6 ± 13.3% (P = 0.002) and 7.2 ± 21.7% (P = 0.03), respectively. A higher baseline arteriolar velocity (ß = -3.9% per mm/s, P = 0.002), glaucoma diagnosis (ß = -21.1%, P = 0.03), and White race (ß = -20.0%, P = 0.01) were associated with decreased velocity in response to arterial hyperoxia. Conclusions: Hyperoxia increased erythrocyte velocity in control and glaucoma suspect participants, but decreased erythrocyte velocity in glaucoma participants, possibly due to impaired autoregulation. Baseline velocity, glaucoma diagnosis, and White race were associated with a decrease in velocity with induction of hyperoxia. Translational Relevance: The European Medicines Agency (EMA) permits precision measurements of blood flow which may aid in the development of biomarkers of glaucoma-related dysregulation of blood flow.

Dexamethasone implant migration in an eye with congenital glaucoma: A case report and review of the literature.

INTRODUCTION: The dexamethasone (DEX) implant is an FDA approved treatment for diabetic macular edema, non-infectious posterior uveitis, and macular edema secondary to branch or central retinal vein occlusions. We describe a case of anterior chamber (AC) migration of a DEX implant in a patient with a history of congenital glaucoma and perform a review of the literature on this particular complication, summarizing the common risk factors, subsequent complications, and management options. CASE DESCRIPTION: A 46-year-old female with a history of congenital glaucoma, status post cataract extraction with insertion of intraocular lens, pars plana vitrectomy, and Baerveldt tube implant in the left eye was referred for post-operative cystoid macular edema (CME). The patient underwent insertion of a DEX implant, resulting in improvement in her CME. After the fourth implant was injected, the patient noticed a white line in her eye while looking in the mirror after doing jumping jacks. Slit lamp examination confirmed migration of the implant into the AC. Ultimately, the patient was taken to the operating room, where her implant was removed via bimanual vitrectomy through an anterior approach. CONCLUSION: This case report and literature review explores the ophthalmic structural changes specific to congenital glaucoma which may have predisposed this eye to anterior migration of the DEX implant. The purpose of this review is to detail the anatomic changes that may increase the risk of anterior chamber implant migration in patients with congenital glaucoma so that physicians may be aware of these risks when selecting patients for this implant.

Measurement of Retinal Microvascular Blood Velocity Using Erythrocyte Mediated Velocimetry.

Changes in retinal blood flow may be involved in the pathogenesis of glaucoma and other ocular diseases. Erythrocyte mediated velocimetry (EMV) is a novel technique where indocyanine green (ICG) dye is sequestered in erythrocyte ghosts and autologously re-injected to allow direct visualization of erythrocytes for in vivo measurement of speed. The purpose of this study is to determine the mean erythrocyte speed in the retinal microvasculature, as well as the intravisit and intervisit variability of EMV. Data from 23 EMV sessions from control, glaucoma suspect, and glaucoma patients were included in this study. In arteries with an average diameter of 43.11 µm ± 6.62 µm, the mean speed was 7.17 mm/s ± 2.35 mm/s. In veins with an average diameter of 45.87 µm ± 12.04 µm, the mean speed was 6.05 mm/s ± 1.96 mm/s. Intravisit variability, as measured by the mean coefficient of variation, was 3.57% (range 0.44-9.68%). Intervisit variability was 4.85% (range 0.15-8.43%). EMV may represent reliable method for determination of retinal blood speed, potentially allowing insights into the effects of pharmacologic agents or pathogenesis of ocular diseases.

Nonmedical Out-of-Pocket Patient and Companion Expenditures Associated With Glaucoma Care.

PURPOSE: Nonmedical out-of-pocket cost to both patients and their companions of office visits for routine glaucoma care has not been extensively studied in the United States. We evaluate potential key predictors of patient expenditures that are critical to assessing the cost-effectiveness of glaucoma health care delivery. MATERIALS AND METHODS: In total, 300 patients responded to the survey in 3 clinics in 2 clinical practice settings. Main outcome measures included both average visit and yearly expenditures. RESULTS: Of the 300 patients, the majority were female (n=187, 62.3%) and African American (n=171, 57.0%). The median age was 66 years. The median [range; mean (SD)] expenditure per patient visit was $22.10 ($11.1, $42.9; $44.1 (72.8)). Patients with companions paid $38.77 more in average visit expenditure (ß: 0.87, P<0.001). The average visit expenditure for retired patients was $17.37 less when compared with nonretired patients (ß: -0.4, P=0.004). Patients living in a rural or suburban area paid $43.91 and $14.13 more per visit, respectively (ß: 0.73, P=0.0004; ß: 0.31, P=0.03), compared with patients living in an urban area. Patients with noncommercial insurance paid $24.01 less in average visit expenditure (ß: -0.66, P=0.0008). The median yearly patient expenditure was $96.70 [$44.6, $222.7; $210.4 (333.9)]. Patients with companions paid $192.37 more in yearly expenditure (ß: 0.9, P<0.001) than those without companions, whereas retired patients paid $80.83 less in yearly expenditure (ß: -0.39, P=0.03) than nonretirees. Patients with noncommercial insurance paid $109.34 less in yearly expenditure (ß: -0.63, P=0.01). CONCLUSIONS: Although a small part of the total cost of glaucoma care, nonmedical out-of-pocket costs constitute a substantial noncovered medical expense to most patients in the United States. Patients who are employed, come with companions, live in nonurban areas, or are on Medicare have greater expenditures.

Referral to Low Vision Services for Glaucoma Patients: Referral Patterns and Characteristics of Those Who Refer.

PURPOSE: To identify characteristics of ophthalmologists and practices who refer glaucoma patients to low vision services (LVS). MATERIALS AND METHODS: An online survey was distributed to members of the American Glaucoma Society. The survey queried demographics of responders and their clinical practices, criteria and barriers to referral to LVS. Survey responders were categorized as high referrers if they reported referring >5 patients to LVS and low referrers if they referred ≤5. χ and Fischer exact tests were used to compare characteristics between high and low referrers. Logistic regression analyses were used to calculate odds ratios and 95% confidence intervals and determine factors associated with referrer status. RESULTS: High referrers to LVS tended to have >10 patients per month who had already seen a low vision provider (53% vs. 10%, P<0.001), reported following the American Academy of Ophthalmology's Preferred Practice Pattern (PPP) recommendations for LVS referrals (38% vs. 18%, P=0.011), and expressed satisfaction with their current referral practices (86% vs. 70%, P=0.049). In the fully adjusted model those who followed PPP were 2.5 times more likely to report being a high referrer as compared with a low referrer (95% confidence interval, 1.1-5.3). However, only 22% of ophthalmologists reported following these guidelines in their practice. The number of years in practice, practice location or type, volume of patients seen each week, and distance to a low vision clinic were not associated with referral. CONCLUSIONS: Familiarity with PPP guidelines may positively influence LVS referral practices.