Customised aberration-controlling corrections for keratoconic patients using contact lenses.

Technological advancements in the design of soft and scleral contact lenses have led to the development of customised, aberration-controlling corrections for patients with keratoconus. As the number of contact lens manufacturers producing wavefront-guided corrections continues to expand, clinical interest in this customisable technology is also increasing among both patients and practitioners. This review outlines key issues surrounding the measurement of ocular aberrations for patients with keratoconus, with a particular focus on the possible factors affecting the repeatability of Hartmann-Shack aberrometry measurements. This review also discusses and compares the relative successes of studies investigating the design and fitting of soft and scleral customised contact lenses for patients with keratoconus. A series of key limitations that should be considered before designing customised contact lens corrections is also described. Despite the challenges of producing and fitting customised lenses, improvements in visual performance and comfortable wearing times, as provided by these lenses, could help to reduce the rate of keratoplasty in keratoconic patients, thereby significantly reducing clinical issues related to corneal graft surgery. Furthermore, enhancements in optical correction, provided by customised lenses, could lead to increased independence, particularly among young adult keratoconic patients, therefore leading to improvements in quality of life.

Optical changes and visual performance with orthokeratology.

Orthokeratology has undergone drastic changes since first described in the early 1960s. The original orthokeratology procedure involved a series of lenses to flatten the central cornea and was plagued by variable results. The introduction of highly oxygen-permeable lens materials that can be worn overnight, corneal topography, and reverse-geometry lens designs revolutionised this procedure. Modern overnight orthokeratology causes rapid, reliable, and reversible reductions in refractive error. With modern designs, patients can wear lenses overnight, remove them in the morning, and see clearly throughout the day without the need for daytime refractive correction. Modern reverse-geometry lens designs cause central corneal flattening and mid-peripheral corneal steepening that provides clear foveal vision while simultaneously causing a myopic shift in peripheral retinal defocus. The peripheral myopic retinal defocus caused by orthokeratology is hypothesised to be responsible for reductions in myopia progression in children fitted with these lenses. This paper reviews the changes in orthokeratology lens design that led to the reverse-geometry orthokeratology lenses that are used today and the optical changes these lenses produce. The optical changes reviewed include changes in refractive error and their time course, high- and low-contrast visual acuity changes, changes in higher-order aberrations and visual quality metrics, changes in accommodation, and changes in peripheral defocus caused by orthokeratology. The use of orthokeratology for myopia control in children is also reviewed, as are hypothesised connections between orthokeratology-induced myopic peripheral defocus and slowed myopia progression in children, and safety and complications associated with lens wear. A better understanding of the ocular and optical changes that occur with orthokeratology will be beneficial to both clinicians and patients in making informed decisions regarding the utilisation of orthokeratology. Future research directions with this lens modality are also discussed.

Advanced Surface Ablation With a New Software for the Reduction of Ablation Irregularities.

PURPOSE: To compare visual outcomes and postoperative aberrations after surface ablation performed with a 750-Hz versus a 1,050-Hz excimer laser coupled with an ablation software designed to reduce corneal surface irregularity. METHODS: Retrospective comparative trial of myopic eyes that had refractive surgery consecutively treated with transepithelial advanced surface ablation with a 750-Hz excimer laser (750 group) versus a 1,050-Hz excimer laser coupled with the Smart Pulse Technology ablation software (SPT group). The SPT algorithm is a laser pulse technology software aimed at reducing surface irregularity of the stromal bed at the end of treatment. The authors evaluated the effect of this smoothing on final visual acuity. Patients were observed for 6 months. RESULTS: A total of 139 eyes in the 750 group and 40 eyes in the SPT group were evaluated. Epidemiological and preoperative refractive data of the two groups were comparable. Uncorrected distance visual acuity improved with time and was significantly better in the SPT group (-0.04 ± 0.61 logMAR for the SPT group vs 0.02 ± 0.78 logMAR for the 750 group) (P < .001). At 6 months, 55% versus 21% achieved 20/16 or better (P = .005) and 90% versus 65% achieved 20/20 or better (P = .019) visual acuity in the SPT and 750 groups, respectively. Corrected distance visual acuity improved with time and appeared to be influenced by group (P = .054), with better results in the SPT group. Coma and trefoil improved significantly with time in a similar manner in both groups. CONCLUSIONS: Surface ablation with the 1,050-Hz excimer laser and SPT software, aimed at reducing the final superficial stromal irregularity, led to improvement of 6-month uncorrected visual acuity. [J Refract Surg. 2017;33(2):89-95.].

Corneal higher-order aberrations after phacoemulsification: a comparison of 3 different incision sizes.

PURPOSE: To analyze the impact of different incision sizes for phacoemulsification on corneal higher-order aberrations (HOA). METHODS: Patients seeking cataract surgery were randomly assigned to one of the following groups: 1.4 mm with biaxial microincision phacoemulsification (25 eyes), 1.8 mm with coaxial phacoemulsification (27 eyes), and 2.2 mm with coaxial phacoemulsification (62 eyes). Inclusion criteria were a minimum age of 18 years and uncomplicated cataract. Exclusion criteria were history of ocular trauma or intraocular surgery, any sign of inflammation or infection, pseudoexfoliation syndrome, glaucoma, optic atrophy, diabetic retinopathy, lens dislocation, cataracta intumescens, cataracta matura, and corneal diseases. Patients underwent phacoemulsification with implantation of an intraocular lens. Aberrometry was performed using an iTrace aberrometer with a pupil scan size of 5.0 mm preoperatively and at postoperative follow-up visits after 1 month. The paired sample t test and analysis of covariance were used for statistical analysis. RESULTS: Ninety patients (114 eyes) were enrolled (mean age 73.7 ± 8.9 years). In all groups, an increase of total HOAs could be measured. The strongest increase was seen in the 2.2 mm group (mean difference 0.031 [95% confidence interval (CI) 0.006-0.056], p = 0.014) and in the 1.4 mm group (mean difference 0.035 [95% CI -0.007 to 0078], p = 0.097). No important difference was found in the 1.8 mm group. CONCLUSIONS: The 2.2 mm and the 1.4 mm incisions seem to have a higher impact on corneal HOAs in comparison to the 1.8 mm incision.

From corneal shape to ocular wavefront in eyes with aspheric IOLs: the feasibility of IOL customisation.

PURPOSE: To determine if it is possible to predict the ocular wavefront aberrations of eyes with an aspheric IOL from the corneal shape and other readily available eye characteristics. A reliable prediction is a prerequisite for future IOL customisation. METHODS: Sixty pseudophakic eyes with aspheric IOLs of 60 patients were included. The corneal shape and the ocular wavefront aberrations were measured postoperatively with a Scheimpflug camera and an aberrometer, respectively. The elevation data of the anterior corneal surface were fitted by Zernike polynomials. Linear regression models for the Zernike coefficients describing the ocular wavefront aberrations up till the fourth order were determined, with as independent variables the Zernike coefficients describing the corneal shape, the eye (right/left), IOL power, and axial length. RESULTS: Linear regression equations with an explained variance (adjusted R-square) above 0.50 were found for five Zernike aberration terms: defocus (z(2,0); adjusted R-square 0.90), the astigmatism terms (0.81 for oblique astigmatism [z(2,-2)] and 0.88 for regular astigmatism [z(2,2)]), vertical coma (z(3,-1); 0.52), and spherical aberration (z(4,0); 0.71). CONCLUSION: The defocus, astigmatism, vertical coma, and spherical aberration terms of the ocular wavefront are strongly associated with the corneal shape in pseudophakic eyes and may thus be predicted from the corneal shape and other eye characteristics.

Control of Induced Spherical Aberration in Moderate Hyperopic LASIK by Customizing Corneal Asphericity.

PURPOSE: To compare differences in induced aberrations and visual acuity after wavefront-optimized LASIK and aspheric-customized LASIK for the treatment of hyperopia. METHODS: Forty consecutive eyes underwent uneventful LASIK for treatment of moderate hyperopia (+3.82 ± 0.63 diopters [D] [+2.75; +5.125]). A standard procedure was performed in the wavefront-optimized LASIK group (n = 24), whereas a postoperative Q-factor equal to zero was scheduled in the aspheric-customized LASIK group (n = 16). RESULTS: At 6 months, mean spherical aberration for a 6-mm pupil diameter was -0.39 ± 0.23 µm (range: -0.76 to 0.01 µm) and Q-factor was -0.52 ± 0.22 (range: -1.00 to -0.12 µm) in the wavefront-optimized group and 0.04 ± 0.18 µm (range: -0.34 to 0.29 µm) and -0.04 ± 0.25 (range: -0.64 to 0.40 µm) in the aspheric-customized LASIK group (P ≤ .05). All remaining outcomes showed no significant differences between groups. UDVA was 20/18.69 ± 0.15 (range: 0.80 to 1.20) in the wavefront-optimized LASIK group and 20/20 ± 0.17 (range: 0.50 to 1.20) in the aspheric-customized LASIK group. One patient in the wavefront-optimized LASIK group lost two or more lines of CDVA and no lines were lost in the aspheric-customized LASIK group. CONCLUSIONS: The results in this small cases series suggest that using an aspheric-customized ablation profile with a target Q-factor equal to 0 in moderate hyperopic LASIK is statistically compatible with a diminishing induced spherical aberration without altering procedural safety when the WaveLight Allegretto 400-Hz excimer laser platform (Alcon Laboratories, Inc., Fort Worth, TX) is used.

Donor cross-linking for keratoplasty: a laboratory evaluation.

PURPOSE: This laboratory-based investigation compares the topographic outcomes of conventional penetrating keratoplasty with that of a novel procedure in which donor corneas are cross-linked prior to keratoplasty. METHODS: Penetrating keratoplasty procedures with continuous running sutures were carried out in a porcine whole globe model. Sixty eyes were randomly paired as 'donor' and 'host' tissue before being assigned to one of two groups. In the cross-linked group, donor corneas underwent riboflavin/UVA cross-linking prior to being trephined and sutured to untreated hosts. In the conventional keratoplasty group, both host and donor corneas remained untreated prior to keratoplasty. Topographic and corneal wavefront measurements were performed following surgery, and technical aspects of the procedure evaluated. RESULTS: Mean keratometric astigmatism was significantly lower in the cross-linked donor group at 3.67D (SD 1.8 D), vs. 8.43 D (SD 2.4 D) in the conventional keratoplasty group (p < 0.005). Mean wavefront astigmatism was also significantly reduced in the cross-linked donor group 4.71 D (SD 2.1) vs. 8.29D (SD 3.6) in the conventional keratoplasty group (p < 0.005). Mean RMS higher order aberration was significantly lower in the cross-linked donor group at 1.79 um (SD 0.98), vs. 3.05 um (SD 1.9) in the conventional keratoplasty group (P = 0.02). Qualitative analysis revealed less tissue distortion at the graft-host junction in the cross-linked group. CONCLUSION: Cross-linking of donor corneas prior to keratoplasty reduces intraoperative induced astigmatism and aberrations in an animal model. Further studies are indicated to evaluate the implications of this potential modification of keratoplasty surgery.

Effect of contact lens on optical coherence tomography imaging of rodent retina.

PURPOSE: To evaluate the effect of powerless contact lens on improving the quality of optical coherence tomography imaging of rodent retina. METHODS: A spectral-domain optical coherence tomography (SD-OCT) system was built for in vivo imaging of rodent retina. The calibrated depth resolution of the system was 3 µm in tissue. A commercial powerless contact lens for rat eye was tested in the experiments. For each rat eye, the retina was imaged in vivo sequentially first without wearing contact lens and then with wearing contact lens. The lateral resolution and signal-to-noise ratio of the OCT images with and without contact lens were compared to evaluate the improvement of image quality. RESULTS: The fundus images generated from the measured 3D OCT datasets with contact lens showed sharper retinal blood vessels than those without contact lens. The contrast of the retinal blood vessels was also significantly enhanced in the OCT fundus images with contact lens. As high as 10 dB improvements in SNR was observed for OCT images with contact lens compared to the images of the same retinal area without contact lens. CONCLUSIONS: We have demonstrated that the use of powerless contact lens on rat eye can significantly improve OCT image quality of rodent retina, which is a benefit in addition to preventing cataract formation. We believe the improvement in image quality is the result of partial compensation of the optical aberrations of the rodent eye by the contact lens.

Comparison of visual acuity, higher-order aberrations and corneal asphericity after refractive lenticule extraction and wavefront-guided laser-assisted in situ keratomileusis for myopia.

AIM: To compare postoperative visual acuity, higher-order aberrations (HOAs) and corneal asphericity after femtosecond lenticule extraction (FLEx) and after wavefront-guided laser-assisted in situ keratomileusis (wfg-LASIK) in myopic eyes. METHODS: We examined 43 eyes of 23 patients undergoing FLEx and 34 eyes of 19 patients undergoing wfg-LASIK to correct myopia. Ocular HOAs were measured by Hartmann-Shack aberrometry and corneal asphericity was measured by a rotating Scheimpflug imaging system before and 3 months after surgery. RESULTS: There was no statistically significant difference in uncorrected (p=0.66 Mann-Whitney U-test) or corrected distance visual acuity (p=0.14) after two surgical procedures. For a 6-mm pupil, the changes in fourth-order aberrations after FLEx were statistically significantly less than those after wfg-LASIK (p<0.001). On the other hand, there were no statistically significant differences in the changes in third-order aberrations (p=0.24) and total HOAs (p=0.13). Similar results were obtained for a 4-mm pupil. The positive changes in the Q value after FLEx were statistically significantly less than those after wfg-LASIK (p=0.001). CONCLUSIONS: In myopic eyes, FLEx induces significantly fewer ocular fourth-order aberrations than wfg-LASIK, possibly because it causes less oblation in the corneal shape, but there was no statistically significant difference in visual acuity or in the induction of third-order aberrations and total HOAs. It is suggested that FLEx is essentially equivalent to wfg-LASIK in terms of visual acuity and total HOA induction, although the characteristics of HOA induction are different.

[Functional results of contact lens correction and penetrating keratoplasty in keratoconus. Report 2. Wavefront analysis].

Comparative analysis of optic aberrations in contact lens correction and after penetrating keratoplasty (PKP) in keratoconus are presented. 117 patients (219 eyes) with stage I-IV keratoconus, wearing rigid gas-permeable contact lenses (RPCL), and 60 patients (64 eyes) after PKP were examined using OPD Scan (NIDEK, Japan) to assess aberration characteristics. Total optic aberrations and higher-order aberrations of ocular and corneal wavefront were significantly increased after PKP compared to those in patients with I-III stage keratoconus wearing RGCL. Astigmatic aberrations after surgery are increased compared to that in patients wearing RGCL regardless of keratoconus stage. Generally, according to objective aberrometry efficacy of PKP is similar to that of contact lens correction in IV stage keratoconus.

Femtosecond laser versus mechanical microkeratome laser in situ keratomileusis for myopia: Metaanalysis of randomized controlled trials.

PURPOSE: To examine differences in efficacy, accuracy, safety, and changes in aberrations between femtosecond and mechanical microkeratome laser in situ keratomileusis (LASIK) for myopia. SETTING: Department of Ophthalmology, Shanghai First People's Hospital Affiliated to Shanghai Jiaotong University, Shanghai, China. DESIGN: Evidence-based manuscript. METHODS: Data sources, including PubMed, Medline, EMBASE, and Cochrane Controlled Trials Register, were searched to identify potentially relevant prospective randomized controlled trials. Primary outcome measures were efficacy (uncorrected distance visual acuity ≥20/20), accuracy (±0.50 diopter mean spherical equivalent), and safety (loss of ≥2 lines of corrected distance visual acuity). Aberrations and postoperative complications were secondary outcomes. RESULTS: Seven prospective randomized controlled trials describing a total of 577 eyes with myopia were included in this metaanalysis. At 6 months or more follow-up, no significant differences were found in the efficacy (odds ratio [OR], 1.17; 95% confidence interval [CI], 0.40 to 3.42; P=.78), accuracy (OR, 1.69; 95% CI, 0.68 to 4.20; P=.26), or safety (OR, 7.37; 95% CI, 0.37 to 147.61; P=.19). In eyes that had femtosecond LASIK, the postoperative total aberrations (mean difference -0.03 µm; 95% CI, -0.05 to -0.01; P=.002) and spherical aberrations (mean difference -0.02 µm; 95% CI, -0.03 to -0.01; P<.00001) were significantly lower. CONCLUSIONS: According to the metaanalysis, femtosecond LASIK did not have an advantage in efficacy, accuracy, and safety measures over mechanical microkeratome LASIK in the early and midterm follow-up, although it might induce fewer aberrations.

Meta-analysis of wavefront-guided vs. wavefront-optimized LASIK for myopia.

PURPOSE: To detect possible differences in clinical outcomes between wavefront-guided laser in situ keratomileusis (LASIK) and wavefront-optimized LASIK for the treatment of myopia. METHODS: A comprehensive literature search of Cochrane Library, MEDLINE, and EMBASE to identify relevant trials comparing LASIK with wavefront-guided and wavefront-optimized. A meta-analysis was performed on the results of the reports. Statistical analysis was performed using RevMan 5.0 software. RESULTS: Seven articles describing a total of 930 eyes were identified. There were no statistically significant differences in the final proportion of eyes achieving uncorrected distance visual acuity of 20/20 or better [odds ratio, 1.04; 95% confidence interval (CI), 0.66 to 1.65; p = 0.86], manifest refractive spherical equivalent within ± 0.50 D of the target (odds ratio, 0.96; 95% CI, 0.53 to 1.75; p = 0.90). No patient lost ≥ 2 lines of distance-corrected visual acuity at posttreatment. The changes in higher order aberrations were not statistically significant different between the two groups with preoperative root-mean-square (RMS) higher order aberrations <0.3 µm (weighted mean difference, 0.01; 95% CI, -0.02 to 0.04; p = 0.57). However, wavefront-guided had a significant better postoperative aberration profile than wavefront-optimized with preoperative RMS higher order aberrations >0.3 µm (weighted mean difference, -0.10; 95% CI, -0.15 to -0.06; p < 0.00001). CONCLUSIONS: Both wavefront-guided and wavefront-optimized LASIK have shown excellent efficacy, safety, and predictability. The wavefront-guided technology may be a more appropriate choice for patients who have preoperative RMS higher order aberrations >0.3 µm.

Six-month clinical outcomes of customized treatments minimized for depth and time in laser corneal refractive surgery.

PURPOSE: Evaluating the application of 2 methods for minimizing the ablated tissue upon objective minimization of depth and time of Zernike-based customized ablations. SETTING: Muscat Eye Laser Center, Muscat, Sultanate of Oman. METHODS: Recently developed algorithms for selection of Zernike terms in customized treatments for refractive surgery were used. Clinical outcomes and tissue-saving attributes were evaluated on 2 groups [minimize depth (MD) and minimize volume (MV); 30 eyes each], plus a control group [corneal wavefront (CW); 30 eyes] with conventional customized approach. Clinical outcomes were evaluated in terms of predictability, safety, and contrast sensitivity and tissue-saving attributes in terms of saved depth and time for each condition (in micrometers, seconds, and percentage) and whether minimized depth or time were less than required for equivalent noncustomized treatments. RESULTS: Ninety-three percent of treatments in the CW group, 93% in the MD group, and 100% in the MV group were within 0.50 diopters of spherical equivalent (SEq) postoperatively. Forty percent of treatments in the CW group, 34% in the MD group, and 47% in the MV group gained at least 1 line of best spectacle-corrected visual acuity postoperatively. Tissue-saving attributes showed an average saved depth of 8 µm (1-20 µm) and a saved time of 6 seconds (1-15 seconds) in the MD group and 6 µm (0-20 µm) and 8 seconds (2-26 seconds) in the MV group. Proposed corrections were always less deep and shorter than full wavefront corrections. In 43% of the MD cases, corrections were less deep, and in 40% of the MV cases, corrections were shorter than equivalent aberration-free treatments. CONCLUSION: The minimization techniques compared here effectively reduced depth and time needed for ablation (up to a maximum of 50% and by 15% in average) without negatively affecting clinical outcomes postoperatively, yielding results equivalent to those of the full customization group.

Optical quality in eyes implanted with aspheric and spherical intraocular lenses assessed by NIDEK OPD-Scan: a randomized, bilateral, clinical trial.

PURPOSE: To determine whether implantation of an intraocular lens (IOL) with an aspheric surface (Akreos AO, Bausch & Lomb Inc) results in reduced ocular aberrations (spherical aberration) and improved Strehl ratio and modulation transfer function (MTF) after cataract surgery. METHODS: In an intraindividual, randomized, double-masked, prospective study of 50 eyes (25 patients) with bilateral cataract, an IOL with modified anterior and posterior surfaces (Akreos AO) was implanted in one eye and a biconvex IOL with spherical surfaces (Akreos Fit, Bausch & Lomb Inc) implanted in the fellow eye. Ocular aberrations, Strehl ratio, and MTF curve with 4.5-, 5.0-, and 6.0-mm pupils were measured with a NIDEK OPD-Scan dynamic retinoscopy aberrometer 3 months after surgery. Uncorrected and corrected distance visual acuity (UDVA and CDVA, respectively) were also measured. RESULTS: No statistically significant difference was noted between eyes in postoperative UDVA and CDVA at 1 month. At 3 months, the Akreos AO IOL group obtained statistically significant lower values of higher order and spherical aberrations with 4.5-, 5.0-, and 6.0-mm pupil diameters than the Akreos Fit IOL group (P<.05). The value of Strehl ratio was statistically significantly higher in eyes with the Akreos AO IOL for 4.5- and 6.0-mm pupils (P<.05). The MTF curve was better in the Akreos AO IOL group in 4.5-, 5.0-, and 6.0-mm pupils (P<.05). CONCLUSIONS: The aspheric Akreos AO IOL induced significantly less spherical aberration than the Akreos Fit IOL for 4.5-, 5.0-, and 6.0-mm pupils. Modulation transfer function and Strehl ratio were also better in eyes implanted with the Akreos AO IOL than the Akreos Fit.

Ocular aberrations and visual performance with an aspheric single-piece intraocular lens: contralateral comparative study.

PURPOSE: To study spherical aberration, coma, and trefoil after implantation of a single-piece aspheric Tecnis intraocular lens (IOL) in cataract patients and the influence on photopic and mesopic contrast sensitivity. SETTING: Ophthalmology Department, Ain-Shams University Hospitals, Cairo, Egypt. METHODS: In this randomized prospective contralateral comparative study, patients had bilateral senile cataract. Eyes with a pathological condition other than cataract that might influence postoperative visual function were excluded. The aspheric IOL was compared with the Sensar AR40e spherical IOL. The IOL selection was randomized. Study criteria included corrected distance visual acuity (CDVA), wavefront aberrometry, and contrast visual acuity. RESULTS: Fifty-six eyes of 28 patients were enrolled. All patients completed the 2-month postoperative visit. There was no significant difference between the IOLs in CDVA (P>.05). Ocular spherical aberration was significantly lower with aspheric IOLs than spherical IOLs (P<.001). Two months after surgery, eyes with the aspheric IOL had better photopic contrast sensitivity and better mesopic contrast sensitivity at all cycles per degree. There was no significant difference in 3rd-order aberrations (coma and trefoil) between IOLs. CONCLUSIONS: After cataract surgery, the single-piece aspheric IOL resulted in significantly lower ocular spherical aberration and significantly better mesopic contrast sensitivity. No significant difference in 3rd-order aberrations indicates that both IOLs had satisfactory centration in the capsular bag.

Visual acuity and higher-order aberrations with wavefront-guided and wavefront-optimized laser in situ keratomileusis.

PURPOSE: To compare visual acuity and higher-order aberrations (HOAs) after wavefront-guided and wavefront-optimized laser in situ keratomileusis (LASIK). METHODS: This retrospective study comprised refraction-matched myopic eyes that had wavefront-guided (Visx Star S4 laser) or wavefront-optimized (WaveLight Allegretto Wave laser) LASIK targeted for emmetropia. Preoperative and postoperative manifest refraction spherical equivalent (MRSE), uncorrected (UDVA) and corrected (CDVA) distance visual acuities, and preoperative and postoperative HOAs were compared. RESULTS: Preoperatively, there were no significant differences between the wavefront-guided and wavefront-optimized groups in age, sex, corneal thickness, MRSE, or HOAs (all P>.05). The mean MRSE was -2.88 diopters (D) +/- 2.6 (SD) and -2.96 +/- 2.6 D, respectively, preoperatively and -0.01 +/- 0.25 D and -0.02 +/- 0.33 D, respectively, postoperatively; 96% of all eyes were within +/-0.50 D of emmetropia postoperatively. There were no differences in UDVA, CDVA, MRSE, or HOAs between groups (all P>.05). The UDVA was 20/20 or better in 85% of eyes in the wavefront-guided group and 86% of eyes in the wavefront-optimized group. All eyes had 20/25 or better CDVA postoperatively; no eye lost 2 lines of CDVA. Fourteen eyes were converted from wavefront-guided to wavefront-optimized treatment because of poor limbal ring alignment (8 eyes), a wave scan not consistent with the manifest refraction (5 eyes), and no iris registration (1 eye). CONCLUSIONS: Wavefront-guided LASIK and wavefront-optimized LASIK produced equivalent visual outcomes and no differences in HOAs. Wavefront-guided treatment could not be performed in many eyes because of difficulties during wavefront measurement.

[Incisions for biaxial and coaxial microincision cataract surgery]. / Inzisionen für die biaxiale und koaxiale mikroinzisionale Kataraktchirurgie.

Microincision cataract surgery (MICS) represents a new level in the development of cataract surgery. Phacoemulsification with intraocular lens (IOL) implantation via incisions of

[Intraocular lenses for microincisional cataract surgery]. / Intraokularlinsen für die mikroinzisionale Kataraktchirurgie.

Incision size in micro-incisional cataract surgery (MICS) is dependent on the minimal size of the folded or rolled intraocular lens (IOL) during implantation and thus the outer diameter of the injector system used. At present implantations through incisions <2.0 mm are possible. MICS IOLs have to be optimized for this small dimension in terms of material and lens body design. Compared to standard procedures, MICS induces little astigmatism and higher order aberrations. Thus MICS procedures provide better predictability in terms of postoperative refractive results. This is of special interest when implanting advanced optic designs, such as aspheric, toric or multifocal IOLs.

Wavefront analysis, contrast sensitivity, and depth of focus after cataract surgery with aspherical intraocular lens implantation.

PURPOSE: To determine whether implantation of an aspherical intraocular lens (IOL) results in reduced ocular aberrations and improved contrast sensitivity after cataract surgery without critical reduction of depth of focus. DESIGN: Double-blinded, randomized, prospective study. METHODS: In an intraindividual study of 25 patients with bilateral cataract, an aspherical IOL (Akreos Advanced Optic [AO]; Bausch & Lomb, Inc., Rochester, New York, USA) was implanted in one eye and a spherical IOL (Akreos Fit; Bausch & Lomb, Inc) in the fellow eye. Higher-order aberrations with a 5- and 6-mm pupil were measured with a dynamic retinoscopy aberrometer at 1 and 3 months after surgery. Uncorrected and best-corrected visual acuity and contrast sensitivity under mesopic and photopic conditions also were measured. Distance-corrected near and intermediate visual acuity were studied as a measurement of depth of focus. RESULTS: There was no statistically significant difference between eyes in uncorrected and best-corrected visual acuity at 1 and 3 months after surgery. There was a statistically significant between-group difference in contrast sensitivity under photopic conditions at 12 cycles per degree and under mesopic conditions at all spatial frequencies. The Akreos AO group obtained statistically significant lower values of higher-order aberrations and spherical aberration with 5- and 6-mm pupils compared with the Akreos Fit group (P < .05). There was no significant difference in distance-corrected near and intermediate visual acuity between both groups. CONCLUSIONS: Aspherical aberration-free Akreos AO IOL induced significantly less higher-order aberrations and spherical aberration than the Akreos Fit. Contrast sensitivity was better under mesopic conditions with the Akreos AO with similar results of depth of focus.