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At least 1,441 records · Page 80Linked to original sources
PubMed1995

Macular capillary particle velocities: a blue field and scanning laser comparison.

BACKGROUND: Two different techniques are available for measurement of macular capillary particle velocities. The psychophysical blue field simulation technique gives data on macular leukocyte flow velocities, while the scanning laser technique provides information on capillary blood velocities of hypofluorescent segments in the macular network. Published velocity data differ considerably between the two methods. The current study was undertaken to compare the two measuring techniques in a group of healthy volunteers. METHODS: Thirty-two healthy subjects (12 man, 20 women, mean age 27 years) participated in this study. All subjects underwent entoptic leukocyte visualization by means of blue field simulation followed by fluorescein angiography using scanning laser ophthalmoscopy. RESULTS: The capillary blood velocities measured using the scanning laser technique were significantly higher (P < 0.01) than the flow velocities estimated with the blue field simulation technique (2.68 +/- 0.3 mm/s vs 0.89 +/- 0.2 mm/s). No significant correlation between the flow velocities was found (r = -0.22). CONCLUSION: The differences may be related to different measuring locations and/or measurements of different phenomena. The blue field technique estimates average leukocyte flow in the macular network, whereas the scanning laser technique quantifies the velocity of erythrocyte aggregates in the capillary lumen of the para- and perifoveal network. A combination of both techniques may be helpful in interpreting physiological responsiveness and altered velocity pattern in diseased eyes.

Adult↗
PubMed1982

Uncertainty in the measurement of fixation disparity due to zones of perceived nonius alignment.

Fixation disparity was measured by means of limits within which nonius alignment was perceived. Two pairs of limits were found, one starting from perceived alignment and the other starting from perceived misalignment. These limits outline zones of perceived alignment of nonius lines. The extent of the zone of first perceived misalignment was found to be greater than that of first perceived alignment. The zone width can be expressed either in terms of disparity at a particular prism vergence or as a range of prism vergence at a particular disparity. The latter expression is comparable to what has been called the range of zero-associated phoria.

Computers↗
PubMed1992

A clinical evaluation of XPERT NCT (Reichert) for glaucoma screening by optometrists.

XPERT NCT advanced logic pneumotonometer (Reichert) was studied for its reliability and use in glaucoma screening. The evaluated 2400 NCT measurements on 300 eyes were compared to the results of Goldmann applanation tonometry (GAT) from the same eyes. Repeated NCT tonometry had no significant effect on IOP. Local anesthesia reduced mean NCT-GAT difference and standard deviation significantly (p < 0.05), i.e. feeling due to the diminished air pulse force provided by the instrument had still considerable influence on IOP. NCT-GAT regression was significant (p < 0.01). Mean IOP readings provided by NCT were four mmHg higher than GAT values. Although accuracy was not satisfactory for exact measuring, it was satisfactory for screening. The results suggested that four mmHg less than the mean IOP value seen on the display is acceptable for screening when the difference between the minimal and maximal individual readings on the display is less than 2SD i.e. six mmHg. In the case of a greater difference, the maximal value is to be replaced, as NCT tends to read higher values than GAT.

Glaucoma↗
PubMed2001

Agreement between ophthalmologists and optometrists in optic disc assessment: training implications for glaucoma co-management.

BACKGROUND: Many studies have estimated observer variability for optic disc assessment among experts, but there are few data on agreement between optometrists and ophthalmologists. The aim of this study is to report inter- and intraobserver agreement among optometrists and ophthalmologists in optic disc assessment and discuss the implications for glaucoma co-management. METHODS: Twelve observers (six optometrists and six ophthalmologists) graded 48 stereo-pairs of optic disc photographs from 48 patients on two separate occasions. Observers graded the vertical C/D ratio, the narrowest rim width and the presence/absence of disc haemorrhage. Agreement was assessed by calculating the standard deviation (SD) of differences and the kappa statistic, within and between observers. Systematic differences in grading between and within individuals were described by calculating mean differences. RESULTS: Intra-observer agreement is "substantial" and significantly better than inter-observer agreement for all disc features (P<0.0001). Intra-observer agreement is comparable for optometrists and ophthalmologists with regard to C/D ratio estimates. Although some optometrists show close agreement with ophthalmologists, overall agreement between optometrists and ophthalmologists is significantly worse than agreement among ophthalmologists alone for vertical C/D ratio (P=0.002) and disc haemorrhage (P=0.02). There are fewer inter-observer mean differences that differ significantly from zero among ophthalmologists (7%) than among optometrists (67%; chi2=11.63, P<0.001) or between optometrists and ophthalmologists (69%; chi2=16.7, P<0.001). There is evidence of systematic under-reading of C/D ratios by less experienced optometrists. CONCLUSION: Although individual optometrists can show good agreement with ophthalmologists on disc grading, the variation in individual performance indicates that training and accreditation in disc assessment is an essential prerequisite for participation by optometrists in glaucoma co-management.

Clinical Competence↗