摘要:

Purpose.To investigate within- and between-examiner reliability and validity of hand-held refractometry water content measures of hydrogel lenses.Methods.Nineteen lenses of various nominal water contents were examined by two examiners on two occasions separated by 1 hour. An Atago N2 hand-held refractometer was used for all water content measures. Lenses were presented in a random order to each examiner by a third party, and examiners were masked to any potential lens identifiers. Intraclass correlation coefficients (ICC), 95% limits of agreement, and Wilcoxon signed rank test were used to characterize the within- and between-examiner reliability and validity of lens water content measures.Results.Within-examiner reliability was excellent (ICC, 0.97; 95% limits of agreement, −3.6% to +5.7%), and the inter-visit mean difference of 1.1 ± 2.4% was not biased (p = 0.08). Between-examiner reliability was also excellent (ICC, 0.98; 95% limits of agreement, −4.1% to +3.9%). The mean difference between examiners was −0.1 ± 2.1% (p = 0.83). The mean difference between the nominally reported water content and our water content measures was −2.1 ± 1.7% (p < 0.001); the 95% limits of agreement for this difference were −5.4% to +1.1%.Conclusion.There is good reliability within and between examiners in measuring water content of hydrogel lenses. However, with our sample of lenses, examiners tended to overestimate the nominal water content of hydrogel lenses. As discussed, this bias may be associated with the Brix scale used in refractometry and is material dependent. Therefore, investigators may need to account for bias when measuring hydrogel lens water content via hand-held refractometry.

ISSN:1040-5488    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.Ophthalmoscopic estimation of the vertical cup-to-disc ratio (VCDR) of the optic nerve head is important in the management of patients with glaucoma or who are glaucoma suspects. The purpose of this study was to compare the accuracy of estimation of VCDR obtained with direct ophthalmoscopy with that obtained with fundus biomicroscopy through undilated pupils. Measurements of VCDR obtained with the Heidelberg Retina Tomograph (HRT), a confocal scanning laser ophthalmoscope, were used as a standard.Methods.Thirty young, healthy adults had their optic discs photographed and then imaged and analyzed with the HRT. Due to HRT software limitations, the VCDR could not be calculated automatically, and so a validated VCDR measurement was derived. This was used as the standard against which ophthalmoscopic estimations were compared. Two months later, the subjects had their VCDRs estimated using direct ophthalmoscopy and fundus biomicroscopy performed in random order after varying time intervals. Agreement between ophthalmoscopic VCDR estimation and HRT-derived VCDR measurement was assessed by means of bias plots and the weighted kappa statistic.Results.Compared with the HRT-derived VCDR measurement, both ophthalmoscopic techniques tended to underestimate VCDR. The bias with direct ophthalmoscopy was statistically significant. There were also wide variations in VCDR estimation with direct ophthalmoscopy and fundus biomicroscopy, which were more pronounced with direct ophthalmoscopy. The weighted kappa statistic indicated moderate agreement between fundus biomicroscopy and HRT-derived VCDR measurement. There was poor to fair agreement between direct ophthalmoscopy and HRT-derived VCDR measurement. The level of disagreement was independent of HRT-derived VCDR, optic nerve head size and pupil size for both direct ophthalmoscopy and fundus biomicroscopy.Conclusions.Fundus biomicroscopy enables more accurate, less variable VCDR estimation than direct ophthalmoscopy. The clinician should record which method they used to examine the optic nerve head so that subsequent clinical decisions are not influenced by apparent VCDR changes.

ISSN:1040-5488    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.The hypotensive effect of exercise on intraocular pressure is well documented, however, little is known about the effect of exercise on pulsatile ocular blood flow. This study examines this effect and follows the recovery of intraocular pressure and pulsatile ocular blood flow after a standard exercise period.Methods.Eighteen visually normal subjects participated in a 4-min period of bicycle ergometry. Intraocular pressure and pulsatile ocular blood flow were measured by pneumotonometry before, immediately after exercise, and at regular intervals during the recovery period.Results.Intraocular pressure was found to decrease significantly with strenuous exercise and recovered gradually toward baseline over a period of 30 min. Pulsatile ocular blood flow increased significantly immediately after exercise then returned to baseline levels between 5 and 10 min after stopping exercise.Conclusions.This study confirms the hypotensive effect of exercise on intraocular pressure and shows that exercise significantly increases pulsatile ocular blood flow.

ISSN:1040-5488    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Purpose.Accommodation and vergence both appear to be influenced by multiple nonsensory factors. “Effort-to-see” is one of these factors. This study was designed to assess the extent to which effort-to-see affects accommodation and vergence.Method.Nine volunteers participated in this study. Stimuli were chosen to stimulate selectively either accommodation or vergence. Accommodation and vergence responses were measured while observers viewed each stimulus with the instruction of “concentrate” or “space-out.”Results.Both oculomotor adjustments were accurate when observers “concentrated,” but regressed toward the resting posture during identical stimulus conditions when observers spaced-out. Interesting, individual differences in oculomotor behavior were apparent.Conclusion.This study demonstrates that higher-level attentional factors play an important role in accommodation and vergence for active exploration of the three-dimensional environment.

ISSN:1040-5488    

出版商:OVID    

年代:2003

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:2003

数据来源: OVID