C.-W. Yung

The response of retrobulbar vasculature to hypercapnia in primary open-angle glaucoma and ocular hypertension.

Purpose: To evaluate the physiological effects of hypercapnia on the retrobulbar vasculature in ocular hypertension (OH) and open-angle glaucoma (OAG). Methods: Peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistive index (RI) of the ophthalmic (OA) and central retinal arteries (CRA) were evaluated in 12 eyes with OH and 8 eyes with OAG using color Doppler imaging. Measurements were taken before and during hypercapnia. Results: Patients with OAG were found to have increased EDV (p < 0.035) of the CRA, and decreased PSV (p < 0.097) and EDV (p < 0.098) of the OA, during hypercapnia. Patients with OH had increased PSV (p < 0.062) and EDV (p < 0.072) of the CRA during hypercapnia. Patients with OH also demonstrated a greater percent change in the calculated RI (p < 0.065) of the CRA in response to hypercapnia when compared to OAG. The mean RI of the CRA decreased during hypercapnia. Discussion: Patients with OH were found to have a normal vasodilatory response within the retrobulbar vasculature during hypercapnia resulting in increased volumetric blood flow to the retina while patients with OAG did not, suggesting there is vasospasm at or downstream from the CRA resulting in decreased volumetric blood flow to the retina.

Ocular penetration of levofloxacin, ofloxacin and ciprofloxacin in eyes with functioning filtering blebs : investigator masked, randomised clinical trial

Background/aims: To compare the penetration of levofloxacin, ofloxacin and ciprofloxacin in the aqueous humour of eyes with functioning filtering blebs. Methods: In this investigator-masked study, 48 patients with functioning filtering blebs requiring cataract surgery were randomised into six groups of eight patients. Groups 1, 2 and 3 received topical ofloxacin 0.3% (Ocuflox®), ciprofloxacin 0.3% (Ciloxan®) and levofloxacin (Quixin®) respectively; Groups 4, 5 and 6 received the same treatment with the corresponding oral dose of ofloxacin 400 mg (Floxin), ciprofloxacin 400 mg (Cipro) and levofloxacin 250 mg (Levaquin). Aqueous antibiotic levels were determined by mass spectrometry of aqueous samples from each patient. Results: The mean aqueous level for topical levofloxacin was significantly higher than those achieved by topical ofloxacin or ciprofloxacin (p value = 0.02 and 0.01, respectively). The combination of topical and oral levofloxacin was significantly higher than topical levofloxacin alone (p = 0.05) and the ciprofloxacin combination (p = 0.003) but not significantly higher than the ofloxacin combination therapy. Conclusions: Topical levofloxacin penetrates better than ofloxacin or ciprofloxacin into the aqueous of eyes with functioning filtering blebs. The combination of topical and oral levofloxacin may be preferable in the treatment of bleb-associated infections (NCT 00392275; Clinical trials.gov).