Biomedical subjects

Sühan Tomaç

Publications and source records attributed to Sühan Tomaç.

4 recordsLinked to original sources

PubMed2006

The irvine prism test: does the positive response indicate suppression scotoma?

PURPOSE: To investigate whether the positive prism test response is due to the presence of a suppression scotoma or the absence of bifoveolar fixation. METHODS: Fifty-one subjects with esotropia (microtropia, small-, moderate- or large-angle esotropia), and 22 subjects with nonstrabismic anisometropic amblyopia were examined. The prism test was performed by using base-out prisms of two different powers (4-PD and 30-PD), and base-in prism of 20-PD, as well as base-down prism of 10-PD for each subject. RESULTS: All the subjects with esotropia showed a positive prism test response, whereas all the subjects with nonstrabismic anisometropic amblyopia had a negative prism test response. All the esotropic subjects showed positive response to all magnitudes and positions of the prisms tested. CONCLUSIONS: The positive response to the prism test does not indicate suppression scotoma in subjects with microtropia and small-angle esotropia because all the esotropic subjects showed the positive response regardless of the amount of deviation or the sensorial adaptation mechanisms. Also, the positive response, seen in the esotropic subjects, did not alter to negative by using the prisms of different powers and directions.

Adolescent↗

PubMed2005

The effects of sildenafil on ocular blood flow.

PURPOSE: To investigate the effects of sildenafil, a popular new drug in the treatment of erectile dysfunction, on ocular blood flow. METHODS: This study was designed as a prospective, double-blind, placebo-controlled study. Twenty participants with erectile dysfunction were given a single oral dose of 100 mg sildenafil, while 10 participants with erectile dysfunction were given placebo. All the participants underwent routine systemic and ophthalmological examinations. Intraocular pressure, systolic and diastolic blood pressure and ocular blood flow (ophthalmic, central retinal, short posterior ciliary arteries) were measured in both eyes before and 1 hour after the dose of sildenafil or placebo. Ocular blood flow measurements were performed using colour Doppler ultrasonography. RESULTS: None of the parameters were significantly different between the groups before study drug intake. Although central retinal artery velocities were not changed, ophthalmic artery and short posterior ciliary artery peak systolic velocity, end-diastolic velocity, and mean velocity values were significantly increased 1 hour after drug intake in the sildenafil group compared to the placebo group (p < 0.05). CONCLUSION: Sildenafil causes a significant increase in blood flow in these arteries. A possible role of inhibition of phosphodiesterase-5 in vascular smooth muscles by sildenafil is implicated. Further studies are needed to investigate the effects of sildenafil on ocular blood flow in patients with senile macular degeneration, diabetic retinopathy and glaucoma.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMedDate not supplied

Clinical and sensorial characteristics of microtropia.

PURPOSE: To investigate the clinical characteristics and sensory mechanism of microtropia. METHODS: Twenty patients with primary microtropia were studied. The patients were evaluated by the visuscope, Irvine prism test, Bagolini striated glasses test, Worth 4-dot test (W4D), TNO, and stereo-fly plate of the Titmus test. RESULTS: The patients who had positive cover test and eccentric fixation showed wandering eccentric fixation. The Irvine prism test was positive in all the patients by using prisms of different strengths and positions. All the patients had abnormal fusion at near. At distance, 15 patients had abnormal fusion by the Bagolini glasses and 8 patients had abnormal fusion by the Worth test. Ten patients had gross stereopsis and the remaining 10 had no measurable stereopsis. CONCLUSIONS: The type of microtropia with eccentric fixation without identity is mainly due to the wandering eccentric fixation. All patients with microtropia have abnormal fusion without fixation point scotoma because positive prism test response does not change to normal by using prisms of different strengths and positions. Differences in fusion results are mainly due to the weakness of abnormal fusion rather than fixation point scotoma. With occlusion treatment, amblyopia can be improved, whereas binocular defects of microtropia cannot be improved.

Adolescent↗

PubMedDate not supplied

Binocularity in refractive accommodative esotropia.

PURPOSE: To investigate whether restoration of normal stereo acuity is possible in refractive accommodative esotropia. METHODS: Twenty patients with refractive accommodative esotropia were included in the study. The cycloplegic refraction and the best corrected visual acuity of each patient were recorded. The patients were evaluated by the 4-prism-diopter test, Bagolini striated glasses, the Worth 4-dot test, the TNO stereo test, and the stereo fly plate of the Titmus test. RESULTS: Eight patients had orthotropia with normal retinal correspondence and 12 patients had a small deviation with abnormal retinal correspondence. Nine patients (8 patients with orthotropia and 1 patient with microtropia) demonstrated a gross level of stereo acuity, whereas the others demonstrated no stereopsis. CONCLUSION: In patients with refractive accommodative esotropia, the prognosis is not favorable for restoration of normal stereopsis, even if orthotropia is achieved.

Accommodation, Ocular↗