Correction of presbyopia with refractive multifocal phakic intraocular lenses

PURPOSE: To evaluate the efficacy of and specify the conditions required for implantation of an anterior chamber multifocal phakic intraocular lens (IOL) to correct presbyopia. SETTING: Monticelli Clinic, Marseilles, France. METHOD: Fifty-five eyes of 33 patients (21 women, 12 men) had implantation of a foldable anterior chamber multifocal phakic IOL. The initial refraction was between -5.00 diopters (D) and +5.00 D. The IOL had an addition of +2.50 D. An uncorrected distance acuity of 0.6 or better (decimal scale) and an uncorrected near acuity (Parinaud scale) of 3 or better (Parinaud 2 approximately equal to Jaeger 1) was considered a successful postoperative result. RESULTS: The mean follow-up was 42.6 weeks +/- 18 (SD). Postoperatively, the mean refraction was -0.12 +/- 0.51 D, the mean decimal uncorrected distance acuity was 0.78 +/- 0.20, and the mean Parinaud uncorrected near acuity was 2.3 +/- 0.6. Eighty-four percent of eyes achieved an uncorrected distance acuity of 0.60 or better and an uncorrected near acuity of Parinaud 3 or better. The IOL was explanted in 4 eyes for different, but essentially optical, reasons. No significant anatomic complications were observed. CONCLUSIONS: Implantation of an anterior chamber multifocal phakic IOL to correct presbyopia was effective and gave good predictability. The procedure is reversible in cases of patient intolerance to the IOL, unwanted optical phenomena, or complications. Strict inclusion criteria should be used for patient selection.     

Monitoring and evaluation of refractive error and presbyopia for Vision 2020

Purpose: To develop output and outcome indicators for the correction of refractive error and presbyopia to a level comparable with those advocated by Vision 2020 for cataract. Methods: World Health Organization, Vision 2020 and published eye care intervention literature were searched to find evidence of best practice. This information was used to construct a suite of indicators for monitoring the correction of refractive error and presbyopia. Results: Indicators for the monitoring and evaluation of refractive error and presbyopia correction were proposed, addressing refraction and spectacle dispensing outputs and rates, and refractive error correction and presbyopia correction coverage. Conclusion: Using data collection that should be occurring in everyday clinical practice, the proposed indicators would provide more comprehensive information than those currently suggested by Vision 2020. As such, they would be more useful in the monitoring and evaluation of the correction of refractive error and presbyopia in the context of Vision 2020.     

Epidemiology of refractive errors and presbyopia

Limitations in existing studies of the epidemiological aspects of refraction are attributed to both technical and statistical procedures. Early influences of ocular parameters on refraction are identified accordingly as prematurity and may or may not be involved. Attention is paid to familial and genetic influences, and infants and toddlers are examined as a group separate from schoolchildren and teenagers, who are likely to have experienced significant periods of near work. The effects of sex and geographical distribution are considered both for younger and older age ranges. Special attention is paid to anisometropia, which is shown-apparently for the first time-to increase appreciably among presbyopes. The connection between refractive errors and ocular pathologies is reviewed, and possible means of preventing early onset myopia are examined. Presbyopia is addressed with reference to its geographical distribution and hypothetical links to accommodation insufficiency.     

后房型人工晶体更换术矫治人工晶体术后屈光误差

本文采用后房型人工晶体更换术矫治 ７ 例 （７ 眼） 因人工晶体植入术后所致较大度数屈光误差及屈光参差。结果： 手术中顺利取出原后房型人工晶体 ６ 例 （６ 眼）, １ 例 （１ 眼） 原人工晶体下襻与囊袋间固定粘连难以旋转取出, 剪断下襻后取出含人工晶体上襻的光学部, 后均顺利植入矫正后房型人工晶体。术后随访 ６ 个月至 ３ 年, 裸眼视力 ０４～１０, 双眼屈光力差０～１０ Ｄ。患者均可适应工作及生活需要。利用后房型人工晶体更换术为解决因人工晶体所致的难以适应的屈光误差及屈光参差提供了有效的矫治手段。     

老视屈光手术的个体化途径

老视手术是矫治老视的有效方法之一。随着手术技术的不断提高,临床经验不断积累,老视屈光手术的有效性及安全性得到了明显提升,但远期稳定性仍需改善。目前,激光矫正术是老视屈光手术的主要途径,屈光晶状体植入术、Inlay植入术成为激光手术的重要补充。个体化的手术术式是今后的发展方向。     

Calculating the error in refractive error

Aims and Purpose

To demonstrate a quick way of calculating the optical difference between two refractions using vector analysis, and to express this as a score for examination purposes.

Methods

An existing formula is applied, converted to a defocus equivalent, and then converted to a score. The formula is set out in an Excel spreadsheet.

Results

The spreadsheet enabled rapid assessment of the difference between two refractive errors. Examples are demonstrated.

Conclusion

The spreadsheet was successful in enabling a comparison of any two refractions, expressing the difference either as a correcting (third) refraction, a defocus equivalent or a one-figure score.     

Corneal asphericity and refractive error

The relationship between corneal curvature measured by classical keratometry and refractive error raises the question of a possible systematic relationship between refractive error and the degree of corneal asphericity. A recomputation and analysis of previously published data leads to the conclusion that the different refractive groups have similar values of the parameter 'p' and differ only in the apical radius of the cornea.     

Near retinoscopy and refractive error

Tonic accommodation (TA) was measured in 100 optometry students using near retinoscopy. Subjects were divided into three refractive groups comprising 42 myopes, 48 emmetropes and 10 hyperopes. The myopic group was found to have the lowest values of TA (mean = 0.47 D; s.d. = 0.38 D), the hyperopes the highest (mean = 0.89 D; s.d. = 0.50 D) and the emmetropes intermediate values (mean = 0.65 D; s.d. = 0.42 D). No significant difference was found between subjects exhibiting myopia which was early in onset (prior to the age of 15 years) and those exhibiting late-onset myopia (after the age of 15 years). The results are discussed with respect to theories of refractive error development.