The design and validation of an optical coherence tomography-based classification system for focal vitreomacular traction.

PURPOSE: To develop and validate a classification system for focal vitreomacular traction (VMT) with and without macular hole based on spectral domain optical coherence tomography (SD-OCT), intended to aid in decision-making and prognostication. METHODS: A panel of retinal specialists convened to develop this system. A literature review followed by discussion on a wide range of cases formed the basis for the proposed classification. Key features on OCT were identified and analysed for their utility in clinical practice. A final classification was devised based on two sequential, independent validation exercises to improve interobserver variability. RESULTS: This classification tool pertains to idiopathic focal VMT assessed by a horizontal line scan using SD-OCT. The system uses width (W), interface features (I), foveal shape (S), retinal pigment epithelial changes (P), elevation of vitreous attachment (E), and inner and outer retinal changes (R) to give the acronym WISPERR. Each category is scored hierarchically. Results from the second independent validation exercise indicated a high level of agreement between graders: intraclass correlation ranged from 0.84 to 0.99 for continuous variables and Fleiss' kappa values ranged from 0.76 to 0.95 for categorical variables. CONCLUSIONS: We present an OCT-based classification system for focal VMT that allows anatomical detail to be scrutinised and scored qualitatively and quantitatively using a simple, pragmatic algorithm, which may be of value in clinical practice as well as in future research studies.

The effect of sub-Tenon's anaesthesia on intraocular pressure.

PURPOSE: To assess the effect of sub-Tenon's anaesthesia on intraocular pressure (IOP) prior to cataract surgery. METHODS: Fifty consecutive patients undergoing phacoemulsification of cataract were recruited. Routine sub-Tenon's anaesthesia was administered with 5 ml unpreserved 2% lignocaine. IOPs were measured immediately prior to and at 1, 3, 5 and 10 min after injection. Efficacy was assessed subjectively by the operating surgeon. No ocular compression was used. Pre- and post-injection IOPs were compared using the Wilcoxon signed rank test, whereas all other results were compared with baseline using Student's two-tailed paired t-tests. RESULTS: All patients achieved good analgesia and akinesis. There was no significant difference between the IOP prior to and 1 min after injection. At all time intervals after 3 min there was a significant reduction in IOP compared with the pre-injection measurement. At 5 min, the mean IOP reduction was 2.72 mmHg and at 10 min IOP was lowered by 2.92 mmHg. Both reductions were statistically significant compared with baseline. CONCLUSIONS: Sub-Tenon's anaesthesia does not cause any significant rise in IOP, thereby possibly making it the anaesthetic technique of choice when an increase in IOP is undesirable. There is no indication for the use of an ocular pressure-reducing device when sub-Tenon's anaesthesia is employed.

Effect of morphine or phenobarbital on teicoplanin elimination pharmacokinetics.

Elimination kinetics following a single dose of teicoplanin in rats pre-treated with morphine sulphate (MS), phenobarbital sodium (Pb), and normal saline (NS) were determined. A microbioassay was used to measure teicoplanin levels. A significant increase in the total clearance of teicoplanin was found in rats pre-treated with MS as compared to controls (P < 0.048). Wide variability was observed in the renal and non-renal clearances of teicoplanin. The mean renal clearance for rats pre-treated with MS, Pb and NS was 0.61 +/- 0.07.mL/min/kg, 0.60 +/- 0.13 mL/min/kg, and 0.46 +/- 0.02 mL/min/kg, respectively; the mean non-renal clearance was 0.33 +/- 0.18 mL/min/kg, 0.17 +/- 0.15 mL/min/kg, and 0.08 +/- 0.03 mL/min/kg, respectively. The differences among the groups for renal and non-renal clearance were not statistically significant. The mean apparent volume of distribution of teicoplanin at steady state was significantly lower in the Pb-pre-treated rats as compared to controls (P < 0.043). The mean half-life for MS-, Pb-, and NS pre-treated groups was 8.1 +/- 3.1 h, 5.9 +/- 3.3 h, and 34.6 +/- 20.7 h, respectively. The differences in mean half-life among the groups achieved statistical significance (P < 0.016). The increase in the total clearance of teicoplanin can best be explained by an increase in both renal elimination and hepatic metabolic pathways.