How often are spectacle lenses not dispensed as prescribed?

Spectacles are routinely prescribed by the ophthalmologist and dispensed by the opticians. We investigated how frequently the spectacles are not dispensed as prescribed and whether the frequency of inaccurate spectacles would decrease if the patients, at the time of collecting spectacles, ask the optician to verify that the spectacles have been dispensed accurately. We found inaccurate spectacles in about one-third of our patients and incorrect spherocylinders more frequently with an error in the spherical element and cylinder axis. These inaccuracies decreased significantly when patients while collecting spectacles, asked the optician to verify the accuracy of the spectacles dispensed. It is suggested that while prescribing spectacles, the patients should be made aware of the possibility of dispensing errors. To decrease the frequency of incorrect spectacles, the patients while collecting spectacles, should ask the optician to check whether the spectacles have been dispensed accurately.     

The clinical importance of spectacle lens base curves

This paper discusses the importance of spectacle lens base curves to the practice of optometry. The base curve is defined. Principles of spectacle lens design, and the role of the base curve in spectacle lens design, are explained. Current practices of manufacturers and surfacing laboratories concerning base curves are discussed, as is the role of the optometrist in specifying and measuring lens curves     

Performance of aspheric spectacle lenses

With improvements in spectacle lens technology, several aspheric lens designs have become available in the moderate power range for prescribing by ophthalmic practitioners. Their manufacturers claim that these lenses improve cosmetic appearance and are lighter than equivalent spherical lenses, without sacrificing visual performance attributes such as good off-axis visual acuity and low distortion. We have made measurements of aspheric lenses made by Rodenstock, Essilor, Sola and Hoya, and have compared them with spherical lenses which have minimal off-axis power errors (best form design). Our results generally support the claims. Cosmetic appearance is considerably better for aspheric than for spherical lenses. The reduction in weight for plastic aspheric lenses is 8–32 per cent for 60 mm diameter. The percentage reductions would be less for smaller lenses. Except for a few exceptions, off-axis power errors of aspheric lenses are similar to those of similar power spherical lenses. All the aspheric lenses have similar or less rotatory distortion than spherical lenses of similar power. (Clin Exp Optom 1992; 75: 6: 210–217)     

近视儿童配戴单光镜后的周边屈光研究

目的:研究近视儿童配戴单光镜后对周边视网膜屈光状态的影响。方法:采用自身对照研究。入选10～15岁近视儿童48例,睫状肌麻痹下使用Grand Seiko WAM5500型红外验光仪测量右眼视网膜中心凹0°以及鼻颞侧10°,20°,30°的屈光值,分别在裸眼和配戴单光眼镜时测量。结果:近视儿童的平均屈光度为-3.99±1.22D,相对周边屈光度在水平视野上为远视性离焦。随着注视角度的增大,相对远视性离焦量增大。戴镜后的相对周边远视性离焦量较裸眼时增大(P<0.01)。戴镜前后的J180及J45相比较无统计学差异。结论:近视儿童配戴单光镜后周边视网膜远视性离焦量增大。根据周边视网膜的聚焦状态改进镜片的设计可能会成为近视矫正的新思路。     

Clinical predictors of the optimal spectacle correction for comfort performing desktop tasks

Background: The best strategy for spectacle correction of presbyopia for near tasks has not been determined. Methods: Thirty volunteers over the age of 40 years were tested for subjective accommodative amplitude, pupillary size, fusional vergence, interpupillary distance, arm length, preferred working distance, near and far visual acuity and preferred reading correction in the phoropter and trial frames. Subjects performed near tasks (reading, writing and counting change) using various spectacle correction strengths. Predictors of the correction maximising near task comfort were determined by multivariable linear regression. Results: The mean age was 54.9 years (range 43 to 71) and 40 per cent had diabetes. Significant predictors of the most comfortable addition in univariate analyses were age (p < 0.001), interpupillary distance (p = 0.02), fusional vergence amplitude (p = 0.02), distance visual acuity in the worse eye (p = 0.01), vision at 40 cm in the worse eye with distance correction (p = 0.01), duration of diabetes (p = 0.01), and the preferred correction to read at 40 cm with the phoropter (p = 0.002) or trial frames (p < 0.001). Target distance selected wearing trial frames (in dioptres), arm length, and accommodative amplitude were not significant predictors (p > 0.15). The preferred addition wearing trial frames holding a reading target at a distance selected by the patient was the only independent predictor. Excluding this variable, distance visual acuity was predictive independent of age or near vision wearing distance correction. The distance selected for task performance was predicted by vision wearing distance correction at near and at distance. Conclusions: Multivariable linear regression can be used to generate tables based on distance visual acuity and age or near vision wearing distance correction to determine tentative near spectacle addition. Final spectacle correction for desktop tasks can be estimated by subjective refraction with trial frames.     

Free surface nickel in CE-marked and non-CE-marked spectacle frames

Three hundred and ninety-five new frames were tested for evidence of nickel release using dimethylglyoxime and ammonia. For areas of CE-marked frames in direct contact with the skin a considerable improvement was found over the previous such survey by the authors, carried out before the widespread introduction of CE marking. However, free nickel was found in 6.5% of CE-marked metal frames (excluding titanium and titanium alloy) in such areas and a majority of half joints. Some titanium alloy frames also tested positive for nickel in areas in contact with the skin.     

角膜塑形镜、周边离焦眼镜、单光眼镜对儿童近视控制的一年效果

目的 评价角膜塑形镜、周边离焦眼镜、单光眼镜控制儿童近视进展的一年效果。设计 前瞻性非随机临床对照研究。研究对象 北京市眼科研究所、北京同仁验光配镜中心、北医眼视光远程视觉服务中心的近视儿童321例,其中141例（43.9%,141/321）完成一年随访。平均年龄（11.41±2.29）岁。方法 所有儿童配镜前进行视力、睫状肌麻痹后验光、裂隙灯、Lenstar眼生物参数测量及彩色眼底照相视盘旁萎缩弧分析。根据患者及监护人要求分别选择单光眼镜（single vision spectacle lenses, SV）、角膜塑形镜（orthokeratology, OK）、周边离焦眼镜（peripheral defocus spectacel lenses, PD）三种不同的矫正方式。观察三组间屈光度进展、眼轴增长及视盘旁萎缩弧扩大率的差异。主要指标 配镜前后屈光度、眼轴长度和视盘旁萎缩弧的改变。结果 完成一年随访者SV组47例、 OK镜组70例、PD组24例。平均等效球镜度（-2.89±1.34）D,平均眼轴长度（24.92±0.34）mm。最后随访时,3组儿童眼轴长度均增长,其中OK镜组增长（0.13±0.16）mm,明显低于其他两组（F=48.820,P<0.001）。SV组屈光度增长（-0.77±0.79）D,PD组屈光度增长（-0.94±0.47）D（t=1.080,P=0.283）。SV组、PD组、OK镜组视盘旁萎缩弧扩大率分别为66.7%、38.6%和15.0%（?字2=28.341,P<0.001）。结论 随访一年的结果表明,与单光眼镜、周边离焦眼镜相比,角膜塑形镜控制屈光度进展、眼轴增长、视盘旁萎缩弧扩大的效果最佳。（眼科,2016,25： 302-306）     

与眼镜架相关的儿童少年头眼部参数测量

目的：为我国儿童少年眼镜架设计提供厦门地区儿童少年与眼镜架相关的头－眼部８项生理解剖指标正常值。方法：对厦门市５￣１５岁儿童少年２６００人以电子数显游标卡尺,弯脚规和Ｈｅｒｔｅｌ眼球突出进行了瞳孔距离、眶距、耳根上点眶距,耳根上点间宽,眼球突出度、鼻高、鼻宽和鼻基根角的活体测量。结果：厦门市５￣１７岁儿童少年８项生理指标分别为瞳孔距离５１．５７￣６１．１０ｍｍ、眶距８８．０８￣１０１．３５ｎｍ、耳     

Do tinted spectacle lens wearers have a different personality?

The wearing of tinted spectacle lenses is considered by some health care workers to be a marker of psychopathology or a hypochondriacal personality type. The purpose of this study was to determine whether there is a relationship between the wearing of tinted spectacle lenses and personality type in physically healthy subjects. The Sixteen Personality Factor Questionnaire 5th Edition, a multidimensional standardized self‐report inventory, was used to determine the personality type of 98 participants. Twenty currently wore tinted spectacle lenses for reasons other than ocular disease, sun protection, outdoor or indoor glare reduction, pattern sensitive epilepsy, migraines, reading difficulties or fashion. The remainder did not wear tinted spectacle lenses for any purpose other than sun protection. Tinted lens wear and no tinted lens wear groups were age and gender matched. There was no statistically significant difference in five global personality factors between the no‐tint and tint groups: extraversion (p = 0.31), anxiety (p = 0.75), tough‐mindedness (p = 0.96), independence (p = 0.63), and self‐control (p = 0.87). This suggests that the use of tinted lenses by physically healthy people is unlikely to be an indicator of personality type.     

Effect of multiple antireflection coatings on impact resistance of Hoya Phoenix spectacle lenses

Purpose: To investigate how the impact resistance of Hoya Phoenix spectacle lenses is affected by centre thickness and the application of a multilayer antireflection (MAR) coating. Methods: Four groups of plano lenses were tested: dress thickness with scratch resistant (SR) coating on both surfaces, dress thickness with SR and MAR, industrial thickness with SR and industrial thickness with SR and MAR. Lenses were edged to a clear circular aperture of 50 mm with a 0.5 mm hidden bevel and mounted in a specially‐designed lens support. A pneumatic gun was used to propel a 6.35 mm steel ball at the centre of each lens. Impact speed was varied using the ZEST protocol to determine the threshold breakage speed. Results: The threshold breakage speeds of the dress and industrial thickness SR lenses were 55.1 and 63.2 m/s, respectively and the corresponding threshold breakage speeds for SR‐MAR lenses were 50.1 and 54.7 m/s. All comparisons were statistically significant using Student's t‐test with a rejection level of p < 0.005. Unlike polycarbonate lenses, dress thickness Phoenix lenses do not display ‘oilcanning’ deformation on high energy impact and therefore are less likely to be dislodged from their mountings. Conclusions: We found that the mean impact resistance of the Phoenix lenses was greater than the level required of eye protector lenses by the standards AS/NZS 1337:1992, ANSI Z87.1‐2003 and CSA Z94.3‐02. Similar to CR39 and polycarbonate, the application of MAR to Phoenix lenses reduces their impact resistance, however, they provide an acceptable level of impact protection in industrial settings, where there is little danger of exposure to pointed or sharp‐edged high‐speed missiles.