Posterior segment Intra-Ocular Implant (IOL) dislocation: Predisposing factors, surgical management, outcome analysis

PURPOSE

To evaluate the predisposing factors, management and visual prognosis of intraocular Lens (IOL) dislocation into the posterior segment.

METHODS

The cases of posterior IOL dislocation from January 2012 to May 2017 at 2 centers were reviewed. Only eyes with dislocations requiring IOL explantation or repositioning were included. Predisposing factors, interval between cataract surgery and IOL dislocation, circumstances of onset, management, and postoperative complications are reported.

RESULTS

72 eyes of 72 patients were included. The mean age was 67.6 years. 47 patients (68%) were men. The mean time interval from cataract surgery to IOL dislocation was significantly shorter in the out-of-the bag group than the in-the-bag IOL dislocation group (3.8 months vs 132 months, P=0.002). Predisposing factors for out-of-the-bag IOL dislocation were mainly capsular rupture and/or zonular dehiscence (83%) after complicated cataract surgery. The predisposing factors for in-the-bag IOL dislocation were high myopia (40%), pseudoexfoliation syndrome (40%), previous vitrectomy (38%), or Marfan syndrome (3%) with uneventful cataract surgery. The type of luxated implant was mainly a 3-piece foldable IOL (50%), followed by foldable one-piece IOL (28%) and a rigid one-piece IOL (17%). Most cases of posterior chamber IOL dislocation occurred spontaneously (80%) without a trigger event. Management consisted of a posterior approach in 24 cases (33%) or an anterior approach in 48 cases (67%), associated with IOL repositioning in 20 eyes (28%), and IOL replacement in 34 eyes (47%). Finally, 18 eyes (25%) were left aphakic. Postoperative complications occurred in 7 cases (9.7%).

CONCLUSIONS

Predisposing factors and time from cataract surgery to IOL dislocation were different for out-of-the bag versus in-the-bag IOL dislocation. Management of IOL dislocation varied considerably, depending on surgeon preference and experience. Surgery for IOL dislocation significantly improved best corrected visual acuity and was associated with a low complication rate.

Influence of inhibition of extraneuronal uptake and of O-methylation on the hyperglycaemia caused by sympathomimetic amines in depancreatized rats

This study aimed at testing whether the O-methylating system (extraneuronal uptake + O-methylation) modulates, in-vivo, β-adrenoceptor-mediated responses. The influences of U-0521 (3,4-dihydroxymethylpropiophenone, an inhibitor of catechol-O-methyl transferase (COMT)) and hydrocortisone (an inhibitor of extraneuronal uptake) on the hyperglycaemia evoked by isoprenaline and adrenaline were compared. Both inhibitors enhanced the increase of the plasma glucose level induced by either isoprenaline (0·36 nmol kg−1 min−1) or adrenaline (0·55 nmol kg−1 min−1). The enhancement caused by U-0521 developed faster than that caused by hydrocortisone, but was of the same magnitude. This is the first report of supersensitivity to sympathomimetic amines caused by inhibition of either COMT or extraneuronal uptake in-vivo and for a response not involving smooth muscle cells.

Differences in the handling of the EMG examination at seven European laboratories

This study was undertaken to analyse epidemiological and methodological differences in referral pattern, examination techniques and distribution of diagnoses among different European EMG laboratories. Seven European EMG laboratories filled in questionnaires and sampled 700 cases retrospectively. The use of needle or surface electrodes for nerve studies and the selection of quantitative techniques for muscle studies exhibited considerable variation. The pattern of referral varied with respect to the type of referral source and the neurological expertise of the referring physician. The proportion of patients without any neurophysiological abnormality ranged from 16 to 33%. The 3 most common diagnostic groups were mononeuropathies, polyneuropathies and radiculopathies although a great inter-laboratory variation was found. The proportion of patients with multiple diagnoses varied from 0 to 23% and most of these diagnoses were from a few known combinations. The presence of an inter-laboratory variation suggests that the quality of the EMG examination may be improved by focussing on the use of techniques, strategies and diagnostic criteria.

Supersensitivity to catecholamines after inhibition of extraneuronal uptake (uptake2) or O-methylation

The influence of inhibition of uptake2 and of O-methylation on beta-adrenoceptor-mediated responses of guinea-pig trachea and rat uterus to some catecholamines was compared. The responses were more markedly enhanced by inhibition of O-methylation (by U-0521) than by inhibition of uptake2 (by hydrocortisone). The ranking order for the degree of super-sensitivity caused by either U-0521 or hydrocortisone was different in the two tissues, suggesting differences between the O-methylating systems of those tissues. In experiments with 3H-isoprenaline metabolism, hydrocortisone had a weak inhibitory effect on O-methylation in both tissues.

The guinea-pig trachea O-methylating system is more effective in modulating beta 2- than beta 1-adrenoceptor-mediated responses to isoprenaline

Assuming that responses of the guinea-pig trachea to isoprenaline in the presence of atenolol (10 mumol L-1) are exclusively, or at least predominantly, beta 2-adrenoceptor mediated and that responses to isoprenaline in the presence of ICI 118,551 (erythro-DL-1(7-methylindan-4-yloxyl)-3-isopropylaminobut an-2-ol) (1 nmol L-1) are exclusively, or at least predominantly beta 1-adrenoceptor mediated, the influence of inhibition of COMT by U-0521 (dehydroxy-2-methyl propiophenone) (50 mumol L-1) has been compared in both conditions. U-0521 enhanced beta 2-adrenoceptor mediated responses to isoprenaline 3.3-fold, while those mediated by beta 1-adrenoceptors were enhanced only 2.2-fold. It is concluded that in guinea-pig trachea COMT activity is functionally more effective in modulating responses which are mediated by beta 2-adrenoceptors than responses mediated by beta 1-adrenoceptors.

The saturability of a site of loss and the degree of supersensitivity to agonists which are substrates of this site of loss

The present investigation was undertaken to test the hypothesis that the experimentally determined degree of supersensitivity to an agonist caused by inhibition of a site of loss depends on the ratio "Km of the site of loss/ED50 of the agonist". The influence of inhibition of neuronal uptake by cocaine on the alpha-adrenoceptor-mediated effect of noradrenaline was studied on the dog saphenous vein; the influence of inhibition of COMT by U-0521 on the beta-adrenoceptor-mediated effect of isoprenaline was studied on the dog saphenous vein and on the guinea-pig trachea; the influence of inhibition of acetylcholinesterase by physostigmine on the effect of acetylcholine was studied on the guinea-pig ileum. To further extend the range of values of the ratio "Km/ED50", several concentrations of phentolamine, propranolol or atropine were used to "increase the ED50" of the respective agonist. It was thus possible to determine the degree of supersensitivity caused by inhibition of a site of loss over a range of "Km/ED50" values of 0.02 to 2,307. In seven situations the ratio "Km/ED50" was higher than 10. In all of these cases the supersensitivity caused by inhibition of the site of loss was maximal. In eleven situations the ratio "Km/ED50" was less than 10 and higher than 0.1 and the supersensitivity obtained was sub-maximal but was closer to the maximum, the closer the ratio was to 10. In two situations the ratio was less than 0.1 and no supersensitivity was obtained. The results confirm the hypothesis.