The use of the retinal nerve fiber layer thickness measurement in determining the effects of cardiopulmonary bypass procedures on the optic nerve.

BACKGROUND: Our aim was to determine the effects of cardiopulmonary bypass procedures on the optic nerve by retinal nerve fiber layer thickness measurements. METHODS: Retinal nerve fiber layer thickness was measured using the GDx Nerve Fiber Analyser, 1 day before the surgery and on postoperative days 1, 5 and 30 in 20 patients undergoing coronary artery bypass grafting surgery. RESULTS: Postoperative mean values for retinal nerve fiber layer thickness, except symmetry on the first day and except symmetry and superior nasal ratio on the fifth day, were statsitically decreased. Only the value for the inferior ratio was significantly lower at the end of the first month. CONCLUSIONS: Cardiopulmonary bypass procedures cause a temporary decrease in retinal nerve fiber layer thickness.

The aetiology in paediatric aphakic glaucoma.

PURPOSE: To investigate the causes of glaucoma in children following removal of cataracts. METHODS: In total, 24 patients (37 eyes) with uncomplicated congenital cataracts who developed glaucoma following cataract removal were studied retrospectively. Cataract morphology, surgical technique, postoperative complications, time to glaucoma onset, gonioscopic findings, the presence of microcornea, and the histopathologic characteristics of the filtration angle in one case were the studied parameters. RESULTS: We found a bimodal onset of glaucoma. Early-onset glaucoma occurred at a mean age of 6 months in 15 eyes and delayed-onset glaucoma at a mean age of 12 years in 22 eyes. Early-onset glaucoma was significantly (P=0.018) more likely to be due to angle closure. With delayed-onset glaucoma, the filtration angle is open in 86% of eyes and significantly (P=0.006) more eyes in the delayed-onset group had microcornea. CONCLUSIONS: Performing cataract surgery very early in life in microphthalmic eyes and leaving residual lens material increases the risk for glaucoma. We recommend a prophylactic iridectomy in eyes at risk for pupillary block. Eyes with delayed-onset glaucoma have open filtration angles but with findings consistent with incomplete development of filtration structures. Early age at cataract extraction and microcornea are risk factors for delayed-onset glaucoma.

Retinal nerve fibre layer measurements are reduced in patients with obstructive sleep apnoea syndrome.

PURPOSE: To determine the retinal nerve fibre layer (RNFL) thickness in patients with obstructive sleep apnoea syndrome (OSAS) in order to investigate the possibility of detecting early signs of glaucoma in this population. METHODS: A total of 66 consecutive patients admitted for polysomnographic evaluation of suspected OSAS. Patients underwent an overnight sleep study in an effort to diagnose and determine the severity of OSAS. Patients who had the disease were classified as having mild and severe OSAS, while patients who did not have the disease were classified as controls. All patients received physical, neurological, and ophthalmological evaluation including visual acuity, slit-lamp examination, Goldmann applanation tonometry, gonioscopy with a three mirror contact lens, and fundus examination. After these examinations, patients with glaucoma and patients who had ophthalmological and/or systemic disease known to affect RNFL thickness were excluded from the study. The RNFL thickness was assessed with a scanning laser polarimeter (Nerve Fiber Analyzer GDx, Laser Diagnostic Technologies Inc., San Diego, CA, USA). RESULTS: A total of 34 patients with obstructive sleep apnoea (19 mild, 15 severe) and 20 age-matched controls were included in the study. The thickness of RNFL was reduced in patients with OSAS compared to controls. The decrease in RNFL was found to be correlated with the severity of sleep apnoea (r=0.78, P=0.01). CONCLUSIONS: The sleep apnoea syndrome is correlated with a proportional decrease in the RNFL. Decreased ocular perfusion related to hypoxia and vasospasm associated with OSAS may cause RNFL thinning, which may precede clinically detectable glaucoma.

A case with some clinical findings overlapping to Rubinstein-Taybi, Rubinstein-Taybi-like syndrome or multiple pterygium syndrome: coincidental findings or a new entity?

We report a case with broad, deviated thumb and big, duplicated, deviated toes resembling Rubinstein-Taybi syndrome. But the patient did not have severe mental retardation as in Rubinstein-Taybi syndrome and had no microdeletions on chromosome 16 by FISH-based assay. This patient had mild webbing as seen in multiple pterygium syndrome, but broad-deviated thumb has not been reported in this syndrome. We discuss whether these are coincidental or overlapping findings or whether this is a possible new clinical entity.

Effects of scleral buckling on the retrobulbar haemodynamic changes.

PURPOSE: This study was planned to investigate blood flow changes due to scleral buckling surgery. In addition the effects on these changes of factors related to patient characteristics and operative technique were studied. METHODS: Central retinal artery (CRA) and ophthalmic artery (OA) blood flow velocities were studied with colour Doppler ultrasonography after scleral buckling surgery in 25 patients with unilateral rhegmatogenous retinal detachment. The effects of the patient's age, referral time, aetiological factors, operative technique, cryotherapy width and buckling distance on the haemodynamic changes were noted. RESULTS: Buckling surgery reduces the blood flow velocities in the CRA, but affects OA blood flow less. Encircling is found to be responsible and it is greater in patients with anatomical success. Other factors do not have any significant effect on these changes. CONCLUSIONS: Good anatomical and functional results can be achieved despite these haemodynamic changes. It must be kept in mind that these changes may cause complications in some patients and the surgery must be minimized.

The penetration of ofloxacin into human aqueous humor given by various routes.

This study was designed to measure the concentration of ofloxacin in aqueous humor after topical, oral and intravenous administration in 50 patients undergoing cataract extraction. In Group 1, ofloxacin 0.3% eyedrops were topically instilled ten times and the aqueous humor concentration was 2.73 +/- 0.88 microg/ml. In Group 2, ofloxacin 0.3% eyedrops were topically instilled six times and the aqueous humor concentration was 0.84 +/- 0.61 microg/ml. Aqueous humor concentration 12 hours after 200 mg oral dose in Group 3, was 0.38 +/- 0.12 microg/ml. In Group 4, patients were given ofloxacin as a single intravenous 200 mg dose and the aqueous humor concentration 2 hours after the end of infusion was 0.45 +/- 0.11 microg/ml. Concentrations were determined by high performance liquid chromatography (HPLC) with fluorescence detection. There was a significant difference between Group 1 and the other groups, but not between Group 2 and Groups 3, 4. It was concluded that ofloxacin penetrates the corneal and the blood-aqueous barriers and can achieve good aqueous levels when given topically and systematically. Ofloxacin can be applied topically for external bacterial infections such as conjunctivitis and keratitis. Systematically administered ofloxacin reached higher levels than the MIC for some bacteria which cause endophthalmitis.

Determination of ofloxacin in human aqueous humour by high-performance liquid chromatography with fluorescence detection.

A reversed-phase high-performance liquid chromatographic method is described for the determination of ofloxacin in human aqueous humour; the method involves fluorescence detection (excitation at 290 nm; emission at 500 nm) after direct injection of samples. The method utilized a 100 mm x 8 mm i.d. cartridge column packed with 4 microns Novapak C18 with a mobile phase methanol-acetonitrile-0.4 M citric acid (3:1:10, v/v/v) and a flow rate of 1 ml min-1 at ambient temperature. The retention times for the internal standard pipemidic acid and for ofloxacin were 4.82 and 7.32 min respectively. The mean recovery (+/- ISD) from human aqueous humour was 103.24 +/- 4.45% for ofloxacin at 1 microgram ml-1 (n = 6). The within-day and day-to-day RSDs at 0.1 microgram ml-1 and 1 microgram ml-1 were less than 6.71% (n = 6) and the lower limit of reliable determination corresponding to a signal-to-noise ratio of 2.5:1 was 20 ng ml-1. The assay was shown to be suitable for measuring ofloxacin levels in human aqueous humour samples after topical, oral and intravenous administration.