Agustina Palacio

A comparison of 3D video display and 2D video display in the ability to enhance medical students’ understanding of different steps of vitreoretinal surgical procedures

Purpose We investigated the effect of graded range of horizontal duction on the shape of the peripapillary Bruchs membrane (ppBM) and optic nerve head (ONH). Methods In 50 eyes of 25 normal subjects, the ONH and peripapillary retina were imaged by optical coherence tomography (OCT) in central gaze and incremental angles of add- and abduction. Displacements of the Bruchs membrane opening (BMO), optic cup (OC), and change in ONH angle in eccentric gazes were compared to those of central gaze, in add- and abduction. Results With increasing duction, the nasal edge of the BMO (nBMO) shifted progressively anteriorly in adduction and posteriorly in abduction, while the temporal edge of the BMO (tBMO) shifted posteriorly in adduction and anteriorly in abduction. The summed absolute nBMO and tBMO displacements in 30° and 35° adduction significantly exceeded those in comparable abduction angles (P < 0.005 for both). The ONH progressively tilted temporally in adduction and nasally in abduction; absolute ONH tilt in adduction was significantly greater than that in abduction for 30° and 35° ductions (P < 0.005 for both). BMO displacement and ONH tilt in adduction exhibited bilinear behavior, with greater effects for both at angles exceeding 26°. The OC shifted significantly farther anteriorly in abduction than adduction at every angle from 10° to 35°. Conclusions Horizontal duction deforms the ONH and ppBM, but more in adduction than in abduction, and increasingly so for angles greater than 26°. This behavior is consistent with optic nerve sheath tethering for adduction exceeding 26°.

VITREOMACULAR ADHESION EVOLUTION WITH AGE IN HEALTHY HUMAN EYES.

Purpose: To quantify the changes in vitreomacular interactions that occur with normal aging in normal eyes. Methods: Spectral domain optical coherence tomography (SD-OCT, Spectralis; Heidelberg Engineering, Heidelberg, Germany) foveal scans of subjects with best corrected visual acuity better than 20/40 and no ocular pathology were included in the study. Each scan was analyzed to determine the status of vitreoretinal interface: complete vitreous adhesion, partial posterior vitreous detachment (PVD) with persistent vitreomacular adhesion (VMA), or complete PVD. Area of VMA was delineated using the Spectralis drawing tool and calculated in mm2 for each scan. Subjects, aged 10 years to 97 years, were divided into 9 age groups according to decade of life. Results: Five hundred and sixty-six SD-OCT scans were analyzed. Area of VMA (mm2) decreased sigmoidally (R2 = 0.99) with each decade of life. With aging, percentage of PVD increased while percentage of complete adhesion decreased. Males were found to have significantly larger area of VMA (mm2) compared with females in the fifth through eighth decades of life, P < 0.05. Conclusion: Vitreomacular interface interactions throughout life are age and gender dependent. This adds to our current understanding of the normal aging process undergone by the vitreous, thereby providing assistance in the clinical differentiation between normal and pathologic vitreomacular interactions.

A Sema3C Mutant Resistant to Cleavage by Furin (FR-Sema3C) Inhibits Choroidal Neovascularization.

In age-related macular degeneration (AMD), abnormal sub retinal choroidal neovascularization (CNV) is a major cause of blindness. FR-sema3C is a point mutated form of semaphorin-3C that is resistant to cleavage by furin like pro-protein convertases (FPPC). We have found in previous work that FR-sema3C functions as an anti-angiogenic factor. In this study we investigated the possible use of FR-sema3C as an inhibitor of CNV. FR-sema3C inhibits VEGF as well as PDGF-BB signal transduction in endothelial cells and to less extent bFGF induced signal transduction using a mechanism that does not depend upon the binding of VEGF like the drugs that are currently the mainstay treatment for AMD. CNV was induced in eyes of C57 black mice by laser photocoagulation. Intravitreal injection of FR-Sema3C or aflibercept (VEGF-trap) was then used to inhibit CNV formation. Invading choroidal vessels were visualized a week later by injection of FITC-dextran into the circulation, followed by the measurement of the area of the invading blood vessels. Injection of 0.1 μg FR-Sema3C inhibited CNV by 55% (P<0.01) and was as effective as 5 μg aflibercept. FR-sema3C did not display any adverse effects on retinal function following its injection into eyes of healthy mice as assessed by optokinetic reflex (OKR) and Electro-retinogram (ERG) criteria. Furthermore, FR-sema3C did not induce apoptosis in the retina as determined by TUNEL nor was there any discernable structural damage to the retina as assessed by several immuno-histochemical criteria. Our results suggest that FR-sema3C could perhaps be used for the treatment of AMD, and that it may perhaps be of benefit to patients that do not respond well to current treatments relying on VEGF sequestering agents.

DIABETES ALTERS THE MAGNITUDE OF VITREOMACULAR ADHESION.

Purpose: To quantify the changes in vitreomacular interactions that occur with aging in diabetic eyes in comparison with age-matched control eyes. Methods: Spectral-domain optical coherence tomography (Spectralis; Heidelberg Engineering) foveal scans of diabetic patients, without evidence of cystoid macular edema, were included. Twenty-five raster foveal scans were performed on every subject. Area of vitreomacular adhesion was delineated using the Spectralis drawing tool and calculated in square millimeter. Data collected included gender, race, best-corrected visual acuity, and posterior vitreous detachment status. Subjects were divided into age groups according to decade of life. Results: Spectral-domain optical coherence tomography scans from 141 diabetic patients were analyzed. Area of vitreomacular adhesion (mm2) showed a hyperbolic decline in diabetic patients (35.5 ± 0, 35.0 ± 3, 34.0 ± 3, 33.9 ± 5, 33.7 ± 6, 29.0 ± 11, 23 ± 15, 13 ± 15). With aging, incidence of posterior vitreous detachment increased and incidence of complete attachment decreased. Conclusion: Diabetes affects the magnitude of attachment of the vitreous gel to the macula that results in stronger and longer lasting attachment of the gel throughout life. Gender differences were not noticed in diabetic patients, suggesting that vitreomacular adhesion remains robust in both genders in diabetes despite aging.