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Biomedical subjects

Y Trigo

Publications and source records attributed to Y Trigo.

7 recordsLinked to original sources
PubMed2001

Sildenafil increases ocular perfusion.

PURPOSE: Our goal was to determine whether visual system responses to sildenafil accompany shifts in ocular perfusion. The human choroid, which supports the metabolic function of the outer retina, is an erectile tissue, analogous in many respects to the corpus cavenosum. METHODS: Right eyes of 12 normal adults were evaluated before and 2 h after 50 mg oral dose of sildenafil. Pulsatile ocular blood flow (POBF), intraocular pressure (IOP), Heidelberg retinal flowmetry (HRT), 4.26 cpd, 7.5 Hz temporally-modulated contrast sensitivity (CS), full-threshold C-20 frequency doubling technology (FDT) perimetry, and blood pressure (BP) were measured. RESULTS: POBF (+29.4%; p > 0.016) and CS (+33.6%; p > 0.014%) increased within 110 (+/-7.7) minutes after sildenafil administration. No subject demonstrated decreases in either variable. HRF flow values increase among 7 of the 9 eyes producing stable scans (+8.2%; p > 0.1). FDT values did not change significantly, nor did systemic pulse amplitude or mean IOP. CONCLUSIONS: Since IOP and systemic pulse amplitude both remained stable after sildenafil administration, while POBF values increased to a level nearly one third greater than baseline. It appears sildenafil can induce intrinsic change in the choroidal vasculature, with an apparently positive impact on pericentral contrast sensitivity. This effect may be of clinical utility.

Administration, Oral↗
PubMed2001

Frequency of sustained glaucomatous-type visual field loss and associated optic nerve cupping in Beaver Dam, Wisconsin.

PURPOSE: To determine the prevalence of persisting glaucomatous-type visual field loss in a Midwestern American adult population, in association with four grades of disc cupping. METHODS: On two separate occasions (1988-1990 and 1993-1995) 2955 predominantly Caucasian adults aged 43-84 provided medical history, underwent applanation tonometry, slit-lamp examination, quantitative suprathreshold perimetry and stereoscopic disc analysis as part of the National Institutes of Health-sponsored Beaver Dam Eye Study. Those demonstrating evidence of glaucomatous-type visual field loss at both visits were the subject of the present analysis. Among these individuals, associations were determined for four categories of optic disc cupping (vertical cup/disc < 0.5, > 0.5, > 0.6, > 0.8), intraocular pressure, blood pressure, cardiovascular pathology and prior glaucoma diagnosis. RESULTS: Of the 2955 subjects assessed, 120 (4%; 57 women, 63 men) demonstrated glaucomatous-type visual field defects at each visit. Fifty-five of these 120 (2% of the tested population) also exhibited some degree of disc cupping in a related eye at both visits. Among these 2%, positive associations relating the extent of field loss, cupping and intraocular pressure were confirmed, but the majority in each cupping category had normal eye pressures. Only seven of the 120 were aware of the presence or suspicion of eye disease prior to the screening. CONCLUSIONS: A majority of those found to have visual field loss and optic nerve cupping persisting together in the same eye after 3-5 years had normal pressures in each eye at both visits. Despite good access to medical care, very few who demonstrated persisting cupping and field loss (even among those with elevated eye pressure) were aware of their ocular condition through prior contact with an eye care professional.

Aged↗
PubMed2000

Effects of latanoprost and timolol-XE on hydrodynamics in the normal eye.

PURPOSE: To compare the effects of latanoprost and timolol-XE on ocular pressure and perfusion in healthy adults, with respect to episcleral venous pressure. METHODS: A double-masked, placebo-controlled crossover study of weeklong bedtime treatment with one drop of drug, with placebo contralaterally, followed by a 3-week washout and alternate-drug/contralateral-placebo repeat. Intraocular pressure was measured by applanation and by pneumotonometry, providing pulsatile ocular circulatory estimates. Measurements of episcleral venous pressure were obtained (Friberg method). RESULTS: Twenty subjects participated (five men, 15 women; mean age, 39 years (range, 21 to 55 years); mean baseline intraocular pressure, 13.4 mm Hg). A greater decrease in intraocular pressure was seen among these subjects the morning after initiating treatment with latanoprost (-2.0 mm Hg; P <.0001) than with timolol-XE (-0.9 mm Hg; P =.051) (latanoprost versus timolol DeltaP =.008). This ocular hypotensive effect remained significant that evening with latanoprost (-3.2 mm Hg; P <.0001) but not with timolol XE (-1.0 mm Hg; P =.2). By the morning of day 8, mean intraocular pressure remained 3.2 mm Hg below baseline with latanoprost and 2.3 mm Hg below baseline with timolol-XE (P <.0001 for both drugs). Neither drug altered episcleral venous pressure. Among a subgroup of nine subjects with comparable intraocular pressure reductions with the two drugs, latanoprost treatment was associated with a 16.7% increase in mean pulsatile ocular blood flow (P =.04) through the weeklong treatment interval, consistently higher than during timolol-XE treatment of the same subjects. CONCLUSION: Latanoprost caused an overnight decrease in intraocular pressure in normotensive normal eyes, and both drugs significantly reduced intraocular pressure within 1 week. Intraocular pressure remained higher than episcleral venous pressure throughout treatment with both drugs. Latanoprost was associated with enhanced pulsatile ocular perfusion not seen with timolol-XE treatment.

Adrenergic beta-Antagonists↗
PubMed1998

Clinical classification of glaucomatous visual field loss by frequency doubling perimetry.

PURPOSE: To determine whether the frequency doubling perimeter (FDP) can grade glaucomatous visual function loss in a clinically relevant manner. Sinusoidal gratings < 1 cpd that undergo counterphase flicker > 15 Hz appear to have twice as many bands of light, a phenomenon referred to as the "frequency doubling illusion." Evidence suggests that this psychophysical effect is mediated in part by large-diameter ganglion cells, which are reported to be lost early in the glaucomatous disease process. A portable, commercially available FDP has already demonstrated high diagnostic potential for glaucoma screening. METHODS: Sixty-four eyes of 42 glaucomatous patients and 22 eyes of 14 normal subjects were evaluated by means of both frequency doubling perimetry and Humphrey perimetry. A clinical scoring algorithm modeled after the Hodapp-Parrish-Anderson criteria for scoring Humphrey visual field defects was derived for the FDP at the halfway point of the study, and all participants were reassessed with this algorithm upon its completion. RESULTS: FDP mean and pattern deviation showed strong linear correlations with Humphrey 30-2 mean deviation (R = 0.75; P < .0001) and corrected pattern standard deviation values (R = 0.64; P < .0001). Despite this, neither global index could consistently categorize the graded glaucomatous visual fields in a manner consistent with the Hodapp-Parrish-Anderson criteria. The new FDP scoring algorithm did provide good segregation (73% precise parity, 93% parity within one Humphrey grade). CONCLUSIONS: Sixteen-zone frequency doubling perimetry can segregate glaucomatous visual field loss into pathologic categories approximating those obtained with Humphrey 30-2 perimetry by means of a formula modeled after the Hodapp-Parrish-Anderson criteria.

Algorithms↗
PubMed1997

Dorzolamide hydrochloride and visual function in normal eyes.

PURPOSE: To determine by a pilot study whether standard treatment with the topical carbonic anhydrase inhibitor dorzolamide hydrochloride influences visual function under normal breathing conditions, during carbon dioxide inhalation, or during hyperventilation, and to establish criteria for future larger-scale studies. METHODS: We enrolled 12 normal subjects into this randomized double-masked placebo-controlled crossover study. Each subject was treated with either dorzolamide 2% or placebo, three times daily, for 4 days. After a 2-week washout period, the alternative topical agent was used under identical testing conditions. On day 2 of each treatment phase, contrast sensitivities to sinusoidal gratings of 1 and 4 cycles per degree (cpd) were assessed. On day 4, mean deviation values from full-threshold 10-2 visual fields were obtained. Three sets of each visual function test were obtained before each treatment phase, and in sequence on each testing day, during normal breathing (baseline), inhalation of carbon dioxide-enriched air, and hyperventilation while intraocular pressure was monitored. RESULTS: Contrast sensitivity at 4 cpd decreased significantly (P < .01) during carbon dioxide supplementation with placebo but showed no significant change with dorzolamide. The decrease in contrast sensitivity accompanying hyperventilation was attenuated (by nearly 50% at 1 cpd) during dorzolamide treatment. Dorzolamide treatment was associated with higher perimetry mean deviation values under each treatment condition and was statistically significant (P < .05) at baseline. CONCLUSIONS: Dorzolamide appears to enhance contrast sensitivity in normal subjects during physiologic hypercapnia and hypocapnia at 4 and 1 cpd, respectively. Also, under normal breathing conditions, dorzolamide therapy increases perimetric light sensitivity.

Adult↗