Peroperative microbial contamination of anterior chamber aspirates during extracapsular cataract extraction and phacoemulsification.

BACKGROUND: The normal conjunctival flora is one of the main sources of intraocular contamination during cataract surgery. The theory that the positive anterior chamber (AC) pressure during phacoemulsification (phaco), and the smaller wound utilised, might reduce the rate of contamination was studied. METHODS: The peroperative AC aspirates of 210 consecutive patients undergoing cataract surgery were assessed. In group 1, 100 patients underwent a standard extracapsular cataract extraction (ECCE). In group 2, 110 patients underwent phacoemulsification of the crystal-line lens through a scleral tunnel. AC aspirates from the Simcoe irrigation/aspiration cannula (group 1) and phaco probe (group 2) were collected and microbiological studies performed after direct and enrichment cultures. RESULTS: There were 29 (29%) positives in the ECCE group compared with 22 (20%) positive cultures from AC aspirates in the phaco group. Coagulase negative staphylococcus (CNS) was the commonest contaminant in both groups. CONCLUSION: Although there was a higher rate of AC contamination during ECCE, the difference was not statistically significant (p > 0.10, chi 2 = 2.31).

Visual evoked potentials elicited by a moving unidimensional noise pattern.

(1) Motion onset and offset visual evoked potentials (VEPs) were recorded in normal human subjects using a unidimensional noise pattern moving at 1, 8 and 64 degrees/s. The maximum N1-P1 amplitude of the motion onset response was obtained when using a fine noise pattern (maximum energy at 5.2 cpd) moving at 8 degrees/s. (2) At a velocity of 8 degrees/s, the motion onset response (fine pattern, 0.70 contrast) showed a morphology similar to the pattern disappearance response. Both at a lower (1 degrees/s) and a higher velocity (64 degrees/s) the N1-P1 amplitude of the motion onset complex was significantly reduced. The latency of the motion onset response (8 degrees/s) and the pattern disappearance complex were significantly different. (3) The effect of lowering the spatial content of the noise pattern on the amplitude of the motion onset response was different for the 3 velocities tested: the largest effect was at the lower velocity of 1 degrees/s; there was no similar effect on the pattern disappearance response. (4) With decreasing contrast, the N1-P1 amplitude of the motion onset response at 8 degrees/s decreased, but this reduction in amplitude was much less than that of the disappearance response. The contrast dependency of the motion onset complex was identical for binocular and monocular recordings. (5) Increasing the motion duration or the duration of the interstimulus interval did not alter the general morphology of the motion response.

Colour contrast thresholds are normal in functional amblyopia.

We evaluated colour contrast thresholds in patients with unilateral functional amblyopia. A computer-controlled colour vision test was used to determine colour contrast thresholds along a blue-yellow tritan axis. Prior to the threshold measurement, a heterochromatic flicker brightness test was performed to ensure isoluminance between the test stimulus and the background for every subject individually. Luminance contrast thresholds were also measured using the same computer-based system. Twenty amblyopic patients were tested. All showed normal tritan colour contrast thresholds both for their amblyopic eye and non-amblyopic fellow eye. Luminance contrast thresholds were elevated in all 6 refractive amblyopic eyes, in 4 of 9 strabismic eyes and in 2 of 5 mixed amblyopic eyes. Colour contrast thresholds are normal in functional amblyopia (with central fixation). Whenever elevated tritan colour contrast thresholds are found in patients with a decreased visual acuity, other causes of visual impairment are to be evaluated.

Electroretinographic findings versus fluorescein angiographic appearance of the retina in patients with ischaemic and non-ischaemic central retinal vein occlusion.

We compared the fluorescein angiographic and electroretinographic findings in 39 eyes of 37 patients with a central retinal vein occlusion. We proved that the flash-electroretinogram is a clinically useful test to differentiate the ischaemic type of central retinal vein occlusion from the non-ischaemic type.

Prospective HLA-DR matching in penetrating keratoplasty.

This prospective study examines whether HLA-DR matching has a beneficial effect on corneal graft survival of high risk patients. Until now, 196 donors have been typed in order to provide 20 patients with a matching graft. The results, though preliminary, are very encouraging.

Cyclospora sp.: a coccidian that causes diarrhoea in travellers.

Cyclospora sp. is a coccidian (protozoan) that has been incriminated in cases of diarrhoea in particular among travellers. We report two cases of intestinal Cyclospora infection in immunocompetent Belgians, who travelled to Indonesia. Although the diarrhoea persisted for several days recovery seemed to occur spontaneously.

Haemoglobin measurement: the reliability of some simple techniques for use in a primary health care setting.

The reliability of five simple techniques for the estimation of blood haemoglobin levels was studied under laboratory conditions. The methods tested were the Sahli technique, the Tallqvist method, and the Lovibond comparator with undiluted blood, blood diluted in Drabkin solution, and blood diluted in modified Drabkin solution. The Lovibond comparator technique using undiluted blood was satisfactory in terms of precision and accuracy, and seems suitable for the monitoring of individual patients and for screening for anaemia. The other techniques were less reliable.A detailed procedure was worked out for estimation of the number of screening errors that can be expected with each of these techniques in any epidemiological situation.