ISSN:1040-5488    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:1040-5488    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Purpose.To compare subjective symptoms and signs in a group of individuals who wear silicone-hydrogel lenses on a daily wear basis while they sequentially used two differing care regimens.Methods.Fifty adapted soft-lens wearers were fitted with a silicone-hydrogel lens material (PureVision, Bausch & Lomb). The lenses were worn on a daily wear basis for two consecutive 1-month periods, during which the subjects used either a Polyquad (polyquaternium-1) -based system or a polyaminopropyl biguanide (PHMB) -based system, using a double-masked, randomized, crossover experimental design.Results.Significant levels of relatively asymptomatic corneal staining were observed when subjects used the PHMB-based system, with 37% of subjects demonstrating a level of staining consistent with a classical solution-based toxicity reaction. Only 2% of the subjects exhibited such staining when using the Polyquad-based system. These results were significantly different (p < 0.001). Significant symptoms were not correlated with the degree of staining, with no differences in lens comfort or overall preference being reported between the regimens (p = NS). The only statistically significant difference in symptoms related to minor differences in stinging after lens insertion being reported, with the Polyquad-based system demonstrating less stinging (p < 0.008).Conclusions.Practitioners who fit silicone-hydrogel contact lenses on a daily wear basis should be wary of the potential for certain PHMB-containing multipurpose care systems to invoke corneal staining. Switching to non-PHMB based regimens will eliminate this complication in most instances.

ISSN:1040-5488    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Backround.Few studies have been published of corneal endothelial cell density (ECD) in children, especially in relation to the age and corneal size of the individuals. The possible effect of corneal enlargement on the endothelium was studied, and the results were objectively reviewed in relation to literature reports on corneal diameter and age.Methods.ECD was assessed in 119 children aged 5 to 15 years after endothelial photography with a noncontact specular microscope (Topcon SP-1000 or SP-2000P), followed by manual digitization of cell overlays. The horizontal corneal diameter, as the visible iris diameter, was measured to 0.5-mm accuracy.Results.The mean ± SD value for ECD, calculated using all individual cell area values, was 3542 ± 510 cells/mm2(range, 2576 to 5316), whereas it was 3246 ± 416 cells/mm2(range, 2404 to 4817) if the mean cell area value from each image was used to calculate ECD. The mean horizontal corneal diameter was 11.48 ± 0.58 mm (± SD). The corneal diameter was not obviously age-related for this group, but there were clear trends for younger children to have higher ECD values than older children (p2, depending on the method for calculating ECD.Conclusions.ECD values were found to be significantly correlated to corneal diameter in children aged 5 to 15 years, and this factor should be considered in comparative studies.

ISSN:1040-5488    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Purpose.Because previous studies have reported conflicting evidence, we examined a possible difference in stereoacuity between distance and near, in particular using a random-dot display. We compared distance and near stereoacuities using identical presentation formats at the two distances.Methods.Twelve young adults with low, stable refractive errors and apparently normal binocular vision participated. Stereoacuity was determined with a Mentor B-VAT II using Random Dot E (BVRDE) and Contour Circles (BVC) stereograms presented on a standard monitor (25 × 19.3 cm) at 518 cm (distance-habitual) and a small monitor (2.0 × 1.4 cm) at 40 cm (near-habitual). To examine whether accommodation-convergence influenced stereoacuity, testing at 40 cm was repeated with the addition of +2.50 DS lenses and base-in prisms (near-compensated) that created the same accommodation and convergence demands as for distance-habitual viewing.Results.The two stereotests produced similar findings. Stereoacuity was not significantly different for distance-habitual and near-habitual viewing of the BVRDE (p = 0.43) and BVC (p = 0.79) stereotests. Near-compensated stereoacuity was worse than near-habitual (BVRDE, p = 0.005; BVC, p = 0.004) and distance-habitual (BVRDE, p = 0.05; BVC, p = 0.003) for both stereotests. Because near stereoacuity with yoked prisms (control condition) was the same as without prism (near-habitual), prism-induced optical distortions cannot account for the difference.Conclusions.Stereoacuity was not different at distance and near under normal viewing conditions. The conflict between subject knowledge of target proximity and the optically-induced relaxation of accommodation and convergence, or an inaccurate accommodative-convergence response, might have caused poor near-compensated stereoacuity.

ISSN:1040-5488    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Purpose.To examine the relationship between relative accommodation and general binocular disorders and to establish their importance in the diagnosis of these anomalies.Methods.We analyzed data of negative relative accommodation (NRA) and positive relative accommodation (PRA) in 69 patients with nonstrabismic binocular anomalies.Results.Statistical analysis showed that low values of NRA and PRA were not associated with any particular disorder. High values of PRA (≥3.50 D) were related to the disorders associated with accommodative excess, whereas high values of NRA (≥2.50 D) were not related to accommodative excess. Statistical differences suggested that a high value of PRA could distinguish between anomalies. Sensitivity analysis revealed that high PRA was the most sensitive sign in patients with convergence insufficiency combined with accommodative excess (0.89) and one of the most sensitive signs for subjects with accommodative excess (0.72) and for those with convergence excess combined with accommodative excess (0.70).Conclusions.Anomalous results of NRA were not clearly associated with any dysfunction. High values of PRA were related to disorders associated with accommodative excess, so the sign of a high value of PRA should be considered as one of the diagnostic signs of these anomalies.

ISSN:1040-5488    

出版商:OVID    

年代:2002

数据来源: OVID