正常瞳孔下非球面与球面人工晶状体眼高阶像差对比观察

目的 探讨正常瞳孔下非球面及球面晶状体眼高阶像差的差别,分析计算非球面与球面晶状体消除球面像差的差值,以客观评价非球面人工晶状体的临床效果.方法 回顾性临床对照研究.选取2010年1～4月在深圳市眼科医院行白内障超声乳化联合人工晶状体植入术的患者50例(66只眼).病人进行随机分组,分别植入非球面人工晶状体(KS-AIN)和球面人工晶状体(KS-X).术后1月正常瞳孔下(3～5mm),由itrace波前像差仪测量高阶像差及i-trace3.1软件模拟瞳孔直径3mm及5mm的调制传递函数值MTF.运用两样本t检验进行比较分析.结果 正常瞳孔下非球面组球面像差小于球面组,其差异具有统计学意义(P<0.05);非球面晶状体与球面晶状体相比较可消除球面像差(0.069 ±0.026)μm(D-Value);非球面组高阶像差均方根小于球面组,但差异无统计学意义(P>0.05);彗差、三叶草比较亦无统计学意义(P>0.05);3mm瞳孔下两组晶状体MTF值的比较仅在空间频率5周/度差异有统计学意义(P<0.05).5mm瞳孔下非球面晶状体眼在各空间频率的MTF值均好于球面晶状体眼,比较有统计学意义(P<0.05).结论 正常瞳孔下非球面人工晶状体眼与球面人工晶状体相比,可以有效减少球面像差,提高部分空间频率的对比敏感度,使患者拥有更好地视觉质量,但其不能体现可以减少术眼高阶像差的优势.

Abstract：

Objective To compare the high order aberrations between implantations of aspherical and spherical intraocular lens with normal pupil diameter, calculate and analyze the differences in spherical aberration between the eyes implanted with aspherical and spherical intraocular lens in order to assess the visual quality and investigate the clinical results. Methods Fifty patients(66 eyes)with cataract underwent surgery from Jan 2010 to Apr 2010, and were divided into 2 groups randomly. Group 1: unifocal and aspherical intraocular lens(negative aberration KS-AIN), Group2: unifocal and spherical intraocular lens(KS-X). Sixty-six eyes were included in this study. The aberrations at normal pupil diameter(interval 3mm-5mm)were measured with the i-Trace wavefront aberrometer. Modulation transfer functions were collected at 3mm and 5mm pupil size. Independent-Samples t Test was used to analyze the data. Results No post-operative complication occurred in each group. The average uncorrected visual acuity(UCVA)was ≥ 0.5, and the average best corrected visual acuity(BCVA)was ≥ 0.6. With normal pupil diameter(mean 3.73± 0.49mm), aspheric IOL group showed less spherical aberration than spherical IOL group with statistical significance(P =0.0040.05, t =-3.216), the difference value(D-value)of spherical aberration was 0.069± 0.026?m. Also aspheric IOL group showed less aberration than spherical IOL group in total higher-order root-mean-square(total HOA RMS)values, but with no statistical difference(P >0.05). There were no significant differences in coma and trefoil values between each group(P >0.05). With 3mm pupil diameter, aspheric IOL group provided a statistically better contrast sensitivity only in 5 cycle/degree while a statistically better contrast sensitivity in all spatial frequencies with 5mm pupil diameter. Conclusions The aspheric lens provides the patients better quality of vision at normal pupil size compared to spherical lens because of the decreased spherical aberration and a better contrast sensitivity in part frequencies. However, aspheric lens cannot express its superiority in decreasing total HOA RMS with normal pupil diameter.     

On- and off-eye spherical aberration of soft contact lenses and consequent changes of effective lens power.

BACKGROUND: Soft contact lenses produce a significant level of spherical aberration affecting their power on-eye. A simple model assuming that a thin soft contact lens aligns to the cornea predicts that these effects are similar on-eye and off-eye. METHODS: The wavefront aberration for 17 eyes and 33 soft contact lenses on-eye was measured with a Shack-Hartmann wavefront sensor. The Zernike coefficients describing the on-eye spherical aberration of the soft contact lens were compared with off-eye ray-tracing results. Paraxial and effective lens power changes were determined. RESULTS: The model predicts the on-eye spherical aberration of soft contact lenses closely. The resulting power change for a +/- 7.00 D spherical soft contact lens is +/- 0.5 D for a 6-mm pupil diameter and +/- 0.1 D for a 3-mm pupil diameter. Power change is negligible for soft contact lenses corrected for off-eye spherical aberration. CONCLUSIONS: For thin soft contact lenses, the level of spherical aberration and the consequent power change is similar on-eye and off-eye. Soft contact lenses corrected for spherical aberration in air will be expected to be aberration-free on-eye and produce only negligibly small power changes. For soft contact lenses without aberration correction, for higher levels of ametropia and large pupils, the soft contact lens power should be determined with trial lenses with their power and p value similar to the prescribed lens. The benefit of soft contact lenses corrected for spherical aberration depends on the level of ocular spherical aberration.     

Third-order aberrations of pseudophakic eyes

The aberrations of pseudophakic eyes were analysed by third-order theory assuming thin intraocular lenses. Third-order aberrations with spherical surfaced lenses are quadratic functions of lens shape. Spherical aberration and coma are generally the most rapidly changing aberrations, at small field positions, with change in lens shape. Optimum designs probably lie within the shape factor range at which these attain minimum absolute values (+1.1, spherical aberration; -0.9 to -3.4, coma). The importance of spherical aberration declines relative to that of off-axis aberrations as pupil size decreases. The introduction of a level of corneal asphericity alters each aberration by a constant amount for any lens shape.     

Clinical study of Acrysof IQ aspheric intraocular lenses

Purpose: To determine whether implantation of an aspheric intraocular lens (SN 60 WF Alcon) results in reduced spherical aberration and improved contrast sensitivity after cataract surgery. Methods: Randomized, prospective study. 260 patients/eyes were randomized to receive two intraocular lens types: Alcon Acrysof Natural (136 eyes) and Acrysof IQ (124 eyes). Quality of vision was measured by visual acuity and contrast sensitivity under mesopic and photopic conditions. Ocular aberrations for 4.0‐ and 6.0‐mm pupil were measured with Allegretto Wavelight Analyzer. All ophthalmologic were performed 7, 30 and 90 days postoperatively. Visual function index (VF‐14) questionnaires for cataract symptoms were performed 90 days after surgery by all the patients. Results: After 90 days, all eyes had mean postoperative best spectacle‐corrected visual acuity 0.75. Eyes with the Acrysof IQ had significantly higher contrast sensitivity than eyes with the Acrysof Natural at high and middle spatial frequencies. A significant reduction in spherical aberration after Acrysof IQ implantation was achieved. The Acrysof IQ also had lower values of high‐order aberration with 4.0‐ and 6.0‐mm pupil when compared with the AcrySof Natural. Conclusion: Results show the aspheric Acrysof IQ induced significantly less high‐order aberration and spherical aberration compared with the Acrysof Natural. Contrast sensitivity revealed better values with the Acrysof IQ intraocular lens.     

Wavefront aberrations following laser in situ keratomileusis and refractive lens exchange for hypermetropia

PURPOSE: To compare the magnitude of aberrations in eyes after elective hypermetropic laser in situ keratomileusis (LASIK) and refractive lens exchange (clear lens replacement). METHODS: Forty-nine patients (92 eyes) had hypermetropic LASIK and 28 (48 eyes) had refractive lens exchange; 23 hypermetropic subjects (41 eyes) were the control group. LASIK was performed with the Nidek EC-5000 excimer laser; ablation zones 5.5 to 6.0-mm in diameter with transition zones 7.5 to 8-mm in diameter. For refractive lens exchange, all but four IOLs were made of foldable acrylic. Aberrations and corneal topography were measured with the Nidek OPD-Scan model ARK-10000 more than 12 months after surgery. The higher-order root-mean-square (HORMS) wave aberrations for combined third to sixth Zernike aberration orders and the Zernike spherical aberration coefficient C(0)(4) at both 4.2-mm and 6.0-mm pupil sizes were calculated. RESULTS: For the LASIK group, surgical refractive change correlated significantly with total, corneal, and internal HORMS and spherical aberrations (except with internal spherical aberration for a 4.2-mm diameter pupil). For the refractive lens exchange group, there were no significant correlations of surgical refractive change with any of these factors. Similarly, there were no significant correlations of refraction with any of these factors for the control group. For a 3-diopter change in refraction with 6-mm pupils, LASIK doubled the total HORMS aberrations. LASIK changed the sign of spherical aberration from positive to negative by increasing the negative asphericity of the anterior cornea. Taking age differences between groups into account, refractive lens exchange increased the total HORMS aberrations by 40% compared with that of the control group, but this was not statistically significant. However, refractive lens exchange significantly increased total spherical aberration. CONCLUSION: Refractive lens exchange was a better refractive procedure than LASIK for minimizing total higher order optical aberrations that accompany hypermetropic refractive surgery.     

Comparison of the AcrySof IQ aspheric blue light filter and the AcrySof SA60AT intraocular lenses

PURPOSE: The development of aspheric intraocular lenses (IOL) designed to compensate for the positive spherical aberration of the cornea has been shown to improve the image quality of pseudophakic eyes. This prospective clinical study compared an aspheric IOL with a blue light filter (AcrySof IQ) with its spherical platform--the SA60AT IOL with conventional optic. METHODS: After uneventful phacoemulsification, 42 and 20 eyes were implanted with the AcrySof IQ aspheric lens and the SA60AT, respectively. Six weeks after surgery, higher order aberrations, visual acuity, contrast sensitivity, depth of focus, pupil size, and corneal asphericity were assessed. RESULTS: Visual acuity was good with both IOLs. A significant difference was found regarding spherical aberration. Mean values of spherical aberration, calculated for a 5-mm pupil were 0.20 +/- 0.06 microm with the SA60AT and 0.04 +/- 0.05 microm with the AcrySof IQ lens. Contrast sensitivity was significantly superior in the AcrySof IQ group in 7 of 15 measurement conditions. Asphericity of the cornea proved to be correlated with postoperative ocular spherical aberration. CONCLUSIONS: The aspheric optic design of the AcrySof IQ results in significant reduction of postoperative ocular spherical aberration and improved contrast vision. Measuring the corneal asphericity allows estimation of postoperative ocular spherical aberration.     

Optical quality of the eye after lens replacement with a pseudoaccommodating intraocular lens

PURPOSE: To examine the optical quality of healthy presbyopic eyes before and after implantation of the pseudoaccommodating AcrySof ReSTOR Natural intraocular lens (IOL) (Alcon Laboratories) by measuring visual acuity and wavefront aberrations. SETTING: University of Valencia, Fernández-Vega Ophthalmological Institute, Valencia, Spain. METHODS: Monocular refraction and photopic distance (6 m) and near (0.33 m) visual acuities were determined before and after clear lens extraction with bilateral AcrySof ReSTOR Natural IOL implantation in 30 hyperopic eyes (+0.50 to +4.00 diopters [D]) of presbyopic patients with low astigmatism (< or = 1.00 D). Postsurgical binocular visual acuity was measured over a range of effective distances. Wavefront aberrations were measured before and after surgery. Aberrations for 2 pupil diameters (3.0 mm and 5.0 mm) were decomposed using Zernike polynomials; total, defocus, astigmatism spherical, and coma aberration terms were studied separately. Postimplantation results were compared with preoperative values. RESULTS: Safety and efficacy indices for distance vision were 1.01 and 0.96, respectively. At near, they improved to 1.07 and 1.06, respectively. Vision at intermediate distances was noticeably poorer. Total, defocus, and spherical aberrations changed after IOL implantation with both pupil diameters (P<.01). Total and defocus aberrations were significantly reduced postoperatively. Spherical aberration coefficients changed to negative and less positive values for a 3.0 mm and a 5.0 mm pupil, respectively. CONCLUSIONS: Implantation of the pseudoaccommodating IOL in healthy eyes yielded uncorrected levels of high-contrast, distance, and near acuities comparable to preoperative best corrected values. Higher-order aberration levels appeared to be similar to the preoperative values.     

Image quality in polypseudophakia for extremely short eyes

AIM: To evaluate the image quality produced by polypseudophakia used for strongly hypermetropic and nanophthalmic eyes. METHODS: Primary aberration theory and ray tracing analysis were used to calculate the optimum lens shapes and power distribution between the two intraocular lenses for two example eyes: one a strongly hypermetropic eye, the other a nanophthalmic eye. Spherical aberration and oblique astigmatism were considered. Modulation transfer function (MTF) curves were computed using commercial optical design software (Sigma 2100, Kidger Optics Ltd) to assess axial image quality, and the sagittal and tangential image surfaces were computed to study image quality across the field. RESULTS: A significant improvement in the axial MTF was found for the eyes with double implants. However, results indicate that this may be realised as a better contrast sensitivity in the low to mid spatial frequency range rather than as a better Snellen acuity. The optimum lens shapes for minimum spherical aberration (best axial image quality) were approximately convex-plano for both lenses with the convex surface facing the cornea. Conversely, the optimum lens shapes for zero oblique astigmatism were strongly meniscus with the anterior surface concave. Correction of oblique astigmatism was only achieved with a loss in axial performance. CONCLUSIONS: Optimum estimated visual acuity exceeds 6/5 in both the hypermetropic and the nanophthalmic eyes studied (pupil size of 4 mm) with polypseudophakic correction. These results can be attained using convex-plano or biconvex lenses with the most convex surface facing the cornea. If the posterior surface of the posterior intraocular lens is convex, as is commonly used to help prevent migration of lens epithelial cells causing posterior capsular opacification (PCO), then it is still possible to achieve 6/4.5 in the hypermetropic eye and 6/5.3 in the nanophthalmic eye provided the anterior intraocular lens has an approximately convex-plano shape with the convex surface anterior. It was therefore concluded that consideration of optical image quality does not demand that additional intraocular lens shapes need to be manufactured for polypseudophakic correction of extremely short eyes and that implanting the posterior intraocular lens in the conventional orientation to help prevent PCO does not necessarily limit estimated visual acuity.     

高度近视眼后房型ICL植入术后波前像差的改变

目的:观察高度近视眼有晶状体眼后房型人工晶状体植入后全眼及眼内波前像差的变化。方法:选择行有晶状体眼人工晶状体(implantable collamer lens,ICL)植入术的高度近视眼患者25例50眼,用尼德克波前像差仪测量患者6mm瞳孔区域内术前和术后1mo的波前像差值,对其进行配对t检验。结果:ICL植入眼术后1mo全眼总体波前像差(OPDTotal)、眼内总体波前像差(Internal Total)较术前明显下降(P<0.05)。全眼总体高阶波前像差(OPD High)、全眼总体球面像差(OPDT.SPH)、全眼总体彗差(OPDT.Coma)、全眼总体三叶草(OPDT.Trefoil)、眼内总体彗差(Internal T.Coma)较术前有不同程度升高,具有统计学意义(P<0.05)。角膜总体波前像差(C-Total)、角膜总体高阶波前像差(C-High)、角膜球差(C-T.Sph)、角膜彗差(C-T.Coma)、角膜四叶草(C-T.4Foil)较术前有不同程度升高,角膜三叶草(C-T.Trefoil)较术前明显下降,但差异均无统计学意义。结论:有晶状体眼后房型人工晶状体植入术虽然显著降低了高度近视眼的总体波前像差,但术眼球面像差、彗差、三叶草等高阶波前像差有不同程度增加。     

Limitations of correcting spherical aberration with aspheric intraocular lenses

PURPOSE: Aspheric intraocular lenses (IOLs) are deigned to correct spherical aberration in pseudophakic eyes. We predict the benefit from correcting spherical aberration based on simulations and aberrometry of pseudophakic eyes implanted with spherical IOLs. METHODS: Ray tracing was performed through a model eye with an equi-biconvex spherical IOL and with a spherical aberration-correcting aspheric IOL. The IOLs were increasingly tilted and/or displaced, and the resulting transverse aberrations of 169 rays were transformed into Zernike coefficients for different pupil sizes. The benefit from correcting spherical aberration at individual esopic pupils was investigated by canceling C4(0) in the sets of Zernike coefficients for 41 eyes implanted with spherical IOL. RESULTS: Both the model eye and the real eye data predict that age-related miosis reduces spherical aberration in the eye implanted with a spherical IOL to approximately 1/3 of the spherical aberration at a 6-mm pupil. A reduction of similar magnitude occurs when spherical aberration-induced non-paraxial defocus is corrected by a spectacle lens. For natural mesopic pupils, canceling the Zernike C4(0) coefficient improved the objective image quality at a rate similar to changing defocus by 0.05 diopters. Average decentration and tilt levels diminish the lead of aspheric IOLs over spherical IOLs, depending on the direction of decentration. CONCLUSIONS: The benefit from correcting spherical aberration in a pseudophakic eye is limited for some or all of the following reasons: wearing glasses, age-related miosis, tilt and decentration of IOL, small contribution of spherical aberration to all aberrations, and intersubject variability.     

Balance of corneal horizontal coma by internal optics in eyes with intraocular artificial lenses: evidence of a passive mechanism

It is well known that the aberrations of the cornea are partially compensated by the aberrations of the internal optics of the eye (primarily the crystalline lens) in young subjects. This effect has been found not only for the spherical aberration, but also for horizontal coma. It has been debated whether the compensation of horizontal coma is the result of passive mechanism [Artal, P., Benito, A., & Tabernero, J. (2006). The human eye is an example of robust optical design. Journal of Vision, 6 (1), 1-7] or through an active developmental feedback process [Kelly, J. E., Mihashi, T., & Howland, H. C. (2004). Compensation of corneal horizontal/vertical astigmatism, lateral coma, and spherical aberration by internal optics of the eye. Journal of Vision, 4 (4), 262-271]. In this study we investigate the active or passive nature of the horizontal coma compensation using eyes with artificial lenses, where no active developmental process can be present. We measured total and corneal aberrations, and lens tilt and decentration in a group of 38 eyes implanted with two types of intraocular lenses designed to compensate the corneal spherical aberration of the average population. We found that spherical aberration was compensated by 66%, and horizontal coma by 87% on average. The spherical aberration is not compensated at an individual level, but horizontal coma is compensated individually (coefficients of correlation corneal/internal aberration: -0.946, p<0.0001). The fact that corneal (but not total) horizontal coma is highly correlated with angle lamda (computed from the shift of the 1st Purkinje image from the pupil center, for foveal fixation) indicates that the compensation arises primarily from the geometrical configuration of the eye (which generates horizontal coma of opposite signs in the cornea and internal optics). The amount and direction of tilts and misalignments of the lens are comparable to those found in young eyes, and on average tend to compensate (rather than increase) horizontal coma. Computer simulations using customized model eyes and different designs of intraocular lenses show that, while not all designs produce a compensation of horizontal coma, a wide range of aspheric biconvex designs may produce comparable compensation to that found in young eyes with crystalline lenses, over a relatively large field of view. These findings suggest that the lens shape, gradient index or foveal location do not need to be fine-tuned to achieve a compensation of horizontal coma. Our results cannot exclude a fine-tuning for the orientation of the crystalline lens, since cataract surgery seems to preserve the position of the capsule.     

Dynamic simulation of the effect of soft toric contact lenses movement on retinal image quality.

PURPOSE: To report the development of a tool designed to dynamically simulate the effect of soft toric contact lens movement on retinal image quality, initial findings on three eyes, and the next steps to be taken to improve the utility of the tool. METHODS: Three eyes of two subjects wearing soft toric contact lenses were cyclopleged with 1% cyclopentolate and 2.5% phenylephrine. Four hundred wavefront aberration measurements over a 5-mm pupil were recorded during soft contact lens wear at 30 Hz using a complete ophthalmic analysis system aberrometer. Each wavefront error measurement was input into Visual Optics Laboratory (version 7.15, Sarver and Associates, Inc.) to generate a retinal simulation of a high contrast log MAR visual acuity chart. The individual simulations were combined into a single dynamic movie using a custom MatLab PsychToolbox program. Visual acuity was measured for each eye reading the movie with best cycloplegic spectacle correction through a 3-mm artificial pupil to minimize the influence of the eyes' uncorrected aberrations. Comparison of the simulated acuity was made to values recorded while the subject read unaberrated charts with contact lenses through a 5-mm artificial pupil. RESULTS: For one study eye, average acuity was the same as the natural contact lens viewing condition. For the other two study eyes visual acuity of the best simulation was more than one line worse than natural viewing conditions. CONCLUSIONS: Dynamic simulation of retinal image quality, although not yet perfect, is a promising technique for visually illustrating the optical effects on image quality because of the movements of alignment-sensitive corrections.     

Impact of a modified optic design on visual function: clinical comparative study

PURPOSE: To determine whether implantation of an intraocular lens (IOL) with a modified anterior surface designed to compensate for the positive spherical aberration of the cornea in eyes of cataract patients results in improved pseudophakic quality of vision. SETTING: Department of Ophthalmology, Bundesknappschaft's Hospital, Sulzbach, Germany. METHODS: In an intraindividual randomized study of 45 patients with bilateral cataract, an IOL with a modified anterior surface (Tecnis Z9000, Pharmacia) was compared with a biconvex lens with spherical surfaces (SI-40, Allergan). All patients had bilateral cataract surgery; in 1 eye the Z9000 IOL was implanted and in the other, the SI-40 IOL. After 1 and 3 months, the following investigations were performed: assessment of the anterior and posterior segments including IOL decentration and tilt, pupil size, high- and low-contrast visual acuities, photopic and mesopic contrast sensitivities, and wavefront aberration of the cornea and eye. RESULTS: Thirty-seven patients were examined at all follow-up visits. Although the eyes with the Z9000 IOL had significantly better best corrected visual acuity after 3 months, the improved quality of vision was more apparent when assessing low-contrast visual acuity and contrast sensitivity. Wavefront measurements revealed no significant spherical aberration in eyes with a Z9000 IOL but significantly positive spherical aberration in eyes with an SI-40 IOL. CONCLUSIONS: The clinical results confirm the theoretical preclinical calculations that the spherical aberration of the eye after cataract surgery can be eliminated by modifying the anterior surface of the IOL. The Tecnis Z9000 lens compensates for the positive spherical aberration in older eyes. This leads to a significant improvement, particularly in contrast sensitivity and mesopic visual quality.     

Changes in spherical aberration after lens refilling with a silicone oil

PURPOSE: It may be possible to restore accommodation to presbyopic human eyes by refilling the lens capsular bag with a soft polymer. In the present study, optical changes were measured that occurred in a pig eye model after the refilling of the capsular bag. METHODS: The optical power and spherical aberration in 10 isolated pig lenses were measured under different conditions. They were first determined by using a scanning laser ray-tracing technique over an effective pupil size of 6 mm. Second, the contours of the anterior and posterior lens surface were photographed, and a mathematical ray-tracing was performed by using a polynomial fit through the digitized surface contours, to determine optical power and spherical aberration. Third, the lenses were refilled with a silicone oil until their preoperative lens thickness was reached, and scanning laser ray-tracing, contour photography, and mathematical ray-tracing were repeated. Comparisons between the measurements were made to determine how the change from a gradient refractive index to a homogeneous refractive index influenced spherical aberration. The influence of the change in lens contour on spherical aberration after lens refilling was also studied. RESULTS: The natural lenses had a higher lens power than the refilled lenses (49.9 +/- 1.5 D vs. 36.8 +/- 1.5 D; P < 0.001). Moreover, there was a change in sign from negative spherical aberration before lens refilling (-3.6 D) to positive spherical aberration after lens refilling (7.9 D; P < 0.001). The comparison between scanning laser ray-tracing of the natural lens and mathematical ray-tracing of the photographed surface contours of the natural lens to determine the effect of refractive index substitution (i.e., replacement of a gradient refractive index by a homogeneous refractive index) showed a significant change in spherical aberration from -3.6 +/- 2.0 to 11.0 +/- 2.1 D (P < 0.001). The change in lens contour did not result in a significant change in spherical aberration (P = 0.08) before and after lens refilling with an equal refractive index. CONCLUSIONS: The lower lens power of refilled pig lenses compared to natural lenses was due to the lower refractive index of the refill material. Refilling pig lenses with the silicone oil used in this study resulted in an increase in spherical aberration. This increase was mainly caused by the change from a gradient refractive index to a homogeneous refractive index. The change in lens curvature after lens refilling did not result in an increase in spherical aberration. The influence of lens refilling on spherical aberration of human lenses must be determined in similar experiments in human eyes.     

Optimizing higher-order aberrations with intraocular lens technology

PURPOSE OF REVIEW: Aspheric intraocular lens technology has been implemented during the past 5 years, and more and more intraocular lenses with different amounts of asphericity are becoming available. Despite the efficacy in the correction of spherical aberration and the good results on implanted eyes, the theoretical advantages of aspheric intraocular lenses are still controversial. RECENT FINDINGS: All investigations showed the ability of the aspheric intraocular lenses to correct the positive spherical aberration of the cornea, with variable impact on the total eye wavefront but with constant advantages in the optical quality of the eyes as measured by the Modulation Transfer Function, the Point Spread Function, and the contrast sensitivity of implanted patients. Theoretical studies on model eyes underlined some possible limitations of aspheric intraocular lenses, especially sensitivity to decentration. In addition, the actual optical quality in implanted eyes is also affected by light scattering, a parameter missed by simple aberration analysis. SUMMARY: Aspheric intraocular lenses effectively reduce spherical aberration in implanted eyes, with improvement in optical quality over the parent spherical intraocular lens. The advantages for implanted eyes could be limited by decentration, by small pupil diameter, and by reduced media transparency.     

Image quality in myopic eyes corrected with laser in situ keratomileusis and phakic intraocular lens

PURPOSE: To compare image quality due to higher-order aberrations following laser in situ keratomileusis (LASIK) or implantation of phakic intraocular lens (PIOL) to correct high myopia. METHODS: Postoperative wavefront examinations, normalized to a pupil size of 5.5 mm, were obtained for 19 LASIK and 20 PIOL eyes for the same surgeon over the same time period. Higher-order aberrations and simulated retinal images were compared. RESULTS: For this small sample, the LASIK eyes yielded an average three times more spherical aberration and two times more coma than PIOL eyes. The effects of these differences were visualized using the simulated retinal images. CONCLUSION: Spherical aberration and coma are the major differences between postoperative LASIK and PIOL higher-order aberrations, and simulated retinal images can be used to visualize these effects.     

不同瞳孔直径下非球面及球面人工晶状体植入术后高阶像差的比较

目的:比较不同瞳孔直径下非球面及球面人工晶状体植入术后的高阶像差。方法:回顾性选择60例(60眼)双眼老年性白内障患者。白内障超声乳化术后,按照植入AcrysofIQ(SN60WF)非球面人工晶状体及AcrysofNatural(SN60AT)球面人工晶状体,分为2组。主要观察项目为术后3mo球差(C12)及总高阶像差的均方根(RMSh)。结果:两组术后3mo波前像差检查,瞳孔直径在4,5,6mm时,AcrysofIQ组球差均低于AcrysofNatural组,两组差异有统计学意义(P<0.01)。瞳孔直径4mm时,AcrysofIQ组总高阶像差小于AcrysofNatural组,但差异无统计学意义(P>0.05)。瞳孔直径5mm及6mm时,AcrysofIQ组总高阶像差均低于AcrysofNatural组,且差异有统计学意义(P<0.01)。结论:AcrysofIQ非球面人工晶状体在瞳孔直径大于5mm时能明显降低球差及总高阶像差,从而使患者获得更好的视觉质量。     

The optics of the growing lungfish eye: lens shape, focal ratio and pupillary movements in Neoceratodus forsteri (Krefft, 1870)

Lungfish (order Dipnoi) evolved during the Devonian period and are believed to be the closest living relatives to the land vertebrates. Here we describe the previously unknown morphology of the lungfish eye in order to examine ocular adaptations present in early sarcopterygian fish. Unlike many teleosts, the Australian lungfish Neoceratodus forsteri possesses a mobile pupil with a slow pupillary response similar to amphibians. The structure of the eye changes from juvenile to adult, with both eye and lens becoming more elliptical in shape with growth. This change in structure results in a decrease in focal ratio (the distance from lens center to the retina divided by the lens radius) and increased retinal illumination in adult fish. Despite a degree of lenticular correction for spherical aberration, there is considerable variation across the lens. A re-calculation of spatial resolving power using measured focal ratios from cryosectioning reveals a low ability to discriminate fine detail. The dipnoan eye shares more features with amphibian eyes than with most teleost eyes, which may echo the visual needs of this living fossil.     

球面与非球面IOL在不同瞳孔直径时的对比敏感度与眩光对比敏感度

目的比较球面与非球面人工晶状体（intraocularlens,IOL）在环境照度为85cd.m-2时在3种瞳孔直径：2.0-2.5mm、4-5mm、8mm下的对比敏感度（contrast sensitivi-ty,CS）和眩光对比敏感度（glare contrast sensitivity,GS）的差异。方法收集年龄相关性白内障患者48例（60眼）,行白内障超声乳化吸除或小切口手法摘出联合后房型IOL植入术。根据植入IOL的不同将患者分为2组：球面组和非球面组。30例（35眼）植入球面IOL,18例（25眼）植入非球面IOL。术后1个月检查2组患者在3种瞳孔直径下分别在低频3cycle/degree（cpd）、中频（6cpd）、高频（12cpd、18cpd）时的CS和GS。结果球面IOL组：瞳孔2.0-2.5mm时,各个空间频率的CS与GS之间的差异均无统计学意义;瞳孔4-5mm时,在6cpd、12cpd的CS与GS之间的差异有统计学意义;瞳孔8mm时,全部频率的CS与GS之间的差异均具有统计学意义。非球面IOL组：3个瞳孔直径下各个空间频率的CS与GS之间的差异均无显著性意义。球面与非球面IOL的比较：瞳孔直径2.0-2.5mm及5mm时,在高频段球面与非球面IOL的CS之间的差异有统计学意义;瞳孔8mm时,在低频段两者之间的GS差异有统计学意义,在中频段两者的CS及GS之间差异均具有统计学意义。结论在球面IOL组,随着瞳孔直径的增大,CS及GS均下降,且瞳孔越大,附加眩光时引起CS的下降效应越明显。在非球面IOL组,在各个瞳孔直径时附加眩光均不引起CS的明显下降。瞳孔直径越大,非球面IOL补偿正性球差、减少球面像差的作用越明显。     

非球面与球面人工晶状体植入术后高阶像差及对比度视力的比较

目的:比较非球面和球面人工晶状体植入术后波前像差、裸眼远视力、最佳矫正远视力、对比度视力的差异。方法:年龄相关性白内障患者46例50眼,将其随机分成两组,球面人工晶状体组(A组)23例24眼术中植入ACR6DSE球面人工晶状体;非球面人工晶状体组(B组)23例26眼术中植入具有负球面像差Acri.Smart36A非球面人工晶状体。术后3mo,观察两组患者的裸眼视力、最佳矫正视力、暗背景(25cd/m2)和高亮背景(255cd/m2)下的对比度视力、瞳孔直径(6mm)时的球面像差、彗差和高阶像差的均方根是否存在差异。结果:两组患者术后裸眼远视力、最佳矫正远视力比较差异无统计学意义,亮背景下各对比度视力以及暗背景下100%,25%对比度视力两组比较差异无统计学意义,暗背景下5%,10%低对比度时B组视力好于A组。瞳孔直径6mm时,B组高阶像差的均方根(RMS)、球差、彗差和A组比较差异均有统计学意义,B组RMS、球差、彗差低于A组。结论:Acri.Smart36A非球面人工晶状体植入术后与ACR6DSE球面人工晶状体比较可以明显的减少患者的高阶像差,改善患者的术后暗环境下的低对比度视力。