Changes In Higher-order Aberrations Research Articles

Recovery Evaluation of Induced Changes in Higher Order Aberrations From the Anterior Surface of the Cornea for Different Pupil Sizes After Cessation of Corneal Refractive Therapy

To assess corneal aberration changes induced by corneal refractive therapy (CRT) for different pupil sizes and to examine the recovery after cessation of contact lens wear. A single-center, prospective, and longitudinal study was performed. Thirty-four subjects who underwent CRT for 1 year were included. High-contrast corrected distance visual acuity (CDVA), manifest refraction, and corneal topography were determined during the treatment and 1 month after the discontinuation of the treatment. Corneal aberrations were calculated using the Vol-CT 6.89 software. Corneal spherical aberration, Z(4,0), and root mean square values (RMS) for coma-like, trefoil, tetrafoil, and higher order aberrations (HOAs) were estimated for different pupil sizes (3-, 4-, 5-, 6-, and 7-mm diameters). Early Treatment Diabetic Retinopathy Study charts were used to measure CDVA. The CRT treatment induced a statistically significant increase of all aberrations studied for all pupil diameters. RMS values for coma-like, trefoil, and tetrafoil aberrations and HOAs after cessation of contact lens wear were not statistically significantly different for any of the different pupil diameters studied at baseline. However, Z(4,0) significantly increased from baseline to 1 month after discontinuation of the CRT lens wear for 5-, 6-, and 7-mm diameter pupils. Our results suggest that CRT is a treatment completely reversible at 1 month after cessation of contact lens wear in terms of CDVA, refractive error, and RMS of coma-like aberrations and HOAs for all pupil sizes. However, for spherical aberration, 1 month is not enough to recover to the baseline level.

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

AimTo 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.MethodsWe examined 43 eyes...

Time course of changes in ocular wavefront aberration after administration of eye ointment

To investigate the influence of an eye ointment on ocular aberration. Prospective, comparative study. In 10 normal volunteers, ocular aberration was assessed before and 5, 30 min, 1, 2, 3, 6, and 12 h after administration of ofloxacin eye ointment. Ocular aberration was sequentially measured over a period of 10 s, and the root mean square (RMS) of the second-, third-, fourth-, and total higher-order aberrations (HOAs) were determined. From the sequential changes in total HOAs during 10 s, the fluctuation index (FI) and stability index (SI) were calculated. The obtained data were compared with those of another 17 normal volunteers who received timolol maleate gel-forming ophthalmic solution. No significant changes in second-order RMS were observed after administration of the ointment. HOAs such as third-, fourth-, and total higher-order RMS significantly changed during the study period (P<0.05, repeated-measures analysis of variance). The RMS of each HOA component significantly increased 5 min after administration compared with the baseline values (P<0.05, Dunnett test). FI also increased significantly 5 min after administration (P<0.05), but SI did not change significantly. When compared with the results of the gel-forming solution group, HOAs and FI showed significantly higher values at several time points during 6 h after application (P<0.05, Mann-Whitney U-test). Administration of eye ointment significantly degrades optical quality of the eye by increasing and oscillating HOAs. These changes were more pronounced than those after instillation of gel-forming ophthalmic solution for at least several hours.

Monocular amblyopia and higher order aberrations

This study compared the corneal and total higher order aberrations between the fellow eyes in monocular amblyopia. Nineteen amblyopic subjects (8 refractive and 11 strabismic) (mean age 30±11years) were recruited. A range of biometric and optical measurements were collected from the amblyopic and non-amblyopic eye including; axial length, corneal topography and total higher order aberrations. For a sub-group of eleven non-presbyopic subjects (6 refractive and 5 strabismic amblyopes, mean age 29±10years) total higher order aberrations were also measured during accommodation (2.5D stimuli). Amblyopic eyes were significantly shorter and more hyperopic compared to non-amblyopic eyes and the interocular difference in axial length correlated with both the magnitude of anisometropia and amblyopia (both p<0.01). Significant differences in higher order aberrations were observed between fellow eyes, which varied with the type of amblyopia. Refractive amblyopes displayed higher levels of 4th order corneal aberrations C(4,0)(spherical aberration), C(4,2)(secondary astigmatism 90°) and C(4,−2)(secondary astigmatism along 45°) in the amblyopic eye compared to the non-amblyopic eye. Strabismic amblyopes exhibited significantly higher levels of C(3,3)(trefoil) in the amblyopic eye for both corneal and total higher order aberrations. During accommodation, the amblyopic eye displayed a significantly greater lag of accommodation compared to the non-amblyopic eye, while the changes in higher order aberrations were similar in magnitude between fellow eyes. Asymmetric visual experience during development appears to be associated with asymmetries in higher order aberrations, in some cases proportional to the magnitude of anisometropia and dependent upon the amblyogenic factor.

Wavefront-Guided and Aspheric Ablation for Myopia – One-Year Results of the Zyoptix Personalized Treatment Advanced Algorithm

To evaluate the visual outcome and change in higher-order aberrations (HOAs) 1 year post simultaneous wavefront-guided and aspheric photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK). Prospective interventional case series. Consecutive myopic patients undergoing PRK (38 eyes of 23 patients) and LASIK (42 eyes of 25 patients) using the Technolas 217z100 excimer laser (Technolas Perfect Vision) in a private laser clinic were included. Main outcome measures were uncorrected distance visual acuity (UDVA), manifest refraction (MRSE), HOAs, and spherical aberration (Z(4)(0)). At 1 year, 87% (32/37) of PRK eyes and 81% (30/37) of LASIK eyes had UDVA of 20/20 or better (P = .75). Mean ± SD MRSE was -0.26 ± 0.31 diopters (D) in the PRK and -0.16 ± 0.34 D in the LASIK group (P = .222). There was no significant increase in total HOA root mean square (RMS) in the PRK group. Mean ± SD total HOA RMS increased from 0.402 ± 0.14 μm to 0.496 ± 0.17 μm (P = .013) in the LASIK group at 1 year. Z(4)(0) increased from mean ± SD -0.045 ± 0.12 μm to -0.109 ± 0.15 μm (P = .006, factor 2.42) in the PRK group and did not significantly increase in the LASIK group (mean ± SD -0.16 ± 0.17 μm to -0.17 ± 0.15 μm (P = .469, factor 1.08) at 6 mm pupil. Visual outcome was excellent in both treatment groups. HOAs were still increased following LASIK by a factor of 1.23 but not PRK. Z(4)(0) was not induced by LASIK with the treatment algorithm but was negatively induced in PRK eyes.

Higher-order aberrations after corneal collagen crosslinking for keratoconus and corneal ectasia

To determine changes in higher-order aberrations (HOAs) after corneal collagen crosslinking (CXL). Cornea and refractive surgery practice. Prospective randomized controlled clinical trial. Corneal and ocular HOAs were measured and analyzed using the Pentacam device and Ladarwave aberrometer, respectively, at baseline and 12 months after CXL. Ninety-six eyes (64 keratoconus, 32 ectasia) of 73 patients had CXL. A fellow-eye control group comprised 42 eyes. The mean preoperative total anterior corneal HOAs, total coma, 3rd-order coma, and vertical coma were 4.68 μm ± 2.33 (SD), 4.40 ± 2.32 μm, 4.36 ± 2.30 μm, and 4.04 ± 2.27 μm, respectively. At 1 year, the mean values decreased significantly to 4.27 ± 2.25 μm, 4.01 ± 2.29 μm, 3.96 ± 2.27 μm, and 3.66 ± 2.22 μm, respectively (all P<.001). There were no significant changes in posterior corneal HOAs. The mean preoperative total ocular HOAs, total coma, 3rd-order coma, trefoil, and spherical aberration were 2.80 ± 1.0 μm, 2.60 ± 1.03 μm, 2.57 ± 1.03 μm, 0.98 ± 0.46 μm, and 0.90 ± 0.42 μm, respectively. At 1 year, the mean values decreased significantly to 2.59 ± 1.06 μm, 2.42 ± 1.07 μm, 2.39 ± 1.07 μm, 0.88 ± 0.49 μm, and 0.83 ± 0.38 μm, respectively (all P=.01). After CXL, HOAs were significantly improved compared with the control group. Changes in HOAs were not statistically associated with an improvement in visual acuity or most subjective visual symptoms, however. Corneal and ocular HOAs decreased after CXL, suggesting an improvement in corneal shape.

Changes in Higher Order Aberration According to Tear-Film Instability Analyzed by Continuous Measurement Using Wavefront

Changes in Higher Order Aberration According to Tear-Film Instability Analyzed by Continuous Measurement Using Wavefront

IntraLase Femtosecond Laser vs Mechanical Microkeratomes in LASIK for Myopia: A Systematic Review and Meta-analysis

To evaluate the safety, efficacy, and predictability of IntraLase (Abbott Medical Optics) femtosecond laser-assisted compared to microkeratome-assisted myopic LASIK. A comprehensive literature search of Cochrane Library, PubMed, and EMBASE was conducted to identify relevant trials comparing LASIK with IntraLase femtosecond laser to LASIK with microkeratomes for the correction of myopia. Meta-analyses were performed on the primary outcomes (loss of ≥2 lines of corrected distance visual acuity [CDVA], uncorrected distance visual acuity [UDVA] 20/20 or better, manifest refraction spherical equivalent [MRSE] within ±0.50 diopters [D], final refractive SE, and astigmatism), and secondary outcomes (flap thickness predictability, changes in higher order aberrations [HOAs], and complications). Fifteen articles describing a total of 3679 eyes were identified. No significant differences were identified between the two groups in regards to a loss of ≥2 lines of CDVA (P=.44), patients achieving UDVA 20/20 or better (P=.24), final UDVA (P=.12), final mean refractive SE (P=.74), final astigmatism (P=.27), or changes in HOAs. The IntraLase group had more patients who were within ±0.50 D of target refraction (P=.05) compared to the microkeratome group, and flap thickness was more predictable in the IntraLase group (P<.0001). The microkeratome group had more epithelial defects (P=.04), whereas the IntraLase group had more cases of diffuse lamellar keratitis (P=.01). According to the available data, LASIK with the IntraLase femtosecond laser offers no significant benefits over LASIK with microkeratomes in regards to safety and efficacy, but has potential advantages in predictability.

Corneal Wavefront Aberrations in Patients Wearing Multifocal Soft Contact Lenses for Myopia Control

Purpose: The purpose of this study was to evaluate the change in corneal wavefront aberrations in young adults who have been fit with multifocal soft contact lenses for myopia progression control. Findings have been analyzed for statistical significance and clinical relevance and compared to reportedly successful Orthokeratology outcomes. Methods: The dominant eye of 40 participants (27 women, 13 men; mean age 27.3 ± 3.2 years; range 23 to 39 years) was fit with Proclear Multifocal center distance lenses (Coopervision, Pleasanton, USA) having a variety of distance powers and reading additions. Refractive errors were limited to a range of –6.00 D up to +1.00 D of sphere, and no greater than –1.00 D of cylinder. Corneal wavefront measurements were performed over 6 mm diameters with a Zeiss Atlas 9000 corneal topographer (Zeiss Meditec, Dublin, USA) prior to, and following lens fitting. Data were converted into rectangular Fourier optics terms M, J0, J45 and RMS values for each reading addition were statistically analyzed. Following evaluation of statistical significance and clinical relevance, results were compared to published data from successful Orthokeratology treatments. Results: Statistically significant changes in higher order aberrations were detected for lenses of all reading additions. Lens groups with higher Add-powers demonstrated stronger changes with increased significance. Final RMS values relating to 2nd, 3rd and 4th Zernike Orders reached clinical significance with a wavefront error of 0.10 μm, the equivalent of 0.25D. Moreover, as Add-powers increased, 3rd and 4th order aberrations likewise showed an increase. Pre-fitting astigmatism values accounted for the highest recorded aberrations and remained predominantly unchanged. Conclusion: Proclear Multifocal center-distance contact lenses were found to increase higher order wavefront aberrations in a manner dependent on their Add-power. In comparison to successful Orthokeratology outcomes, the amounts of resulting aberrations are notably different.

Changes in Higher-Order Aberrations after Penetrating Keratoplasty

Changes in Higher-Order Aberrations after Penetrating Keratoplasty

Changes of Higher-Order Aberrations after Microcoaxial Cataract Surgery According to Pupil Size

Changes of Higher-Order Aberrations after Microcoaxial Cataract Surgery According to Pupil Size

Topography-guided hyperopic and hyperopic astigmatism femtosecond laser-assisted LASIK: long-term experience with the 400 Hz eye-Q excimer platform

The purpose of this study was to evaluate the safety and efficacy of topography-guided ablation using the WaveLight 400 Hz excimer laser in laser-assisted in situ keratomileusis (LASIK) for hyperopia and/or hyperopic astigmatism. We prospectively evaluated 208 consecutive LASIK cases for hyperopia with or without astigmatism using the topography-guided platform of the 400 Hz Eye-Q excimer system. The mean preoperative sphere value was +3.04 ± 1.75 (range 0.75-7.25) diopters (D) and the mean cylinder value was -1.24 ± 1.41 (-4.75-0) D. Flaps were created either with Intralase FS60 (AMO, Irvine, CA) or FS200 (Alcon, Fort Worth, TX) femtosecond lasers. Parameters evaluated included age, preoperative and postoperative refractive error, uncorrected distance visual acuity, corrected distance visual acuity, flap diameter and thickness, topographic changes, higher order aberration changes, and low contrast sensitivity. These measurements were repeated postoperatively at regular intervals for at least 24 months. Two hundred and two eyes were available for follow-up at 24 months. Uncorrected distance visual acuity improved from 5.5/10 to 9.2/10. At 24 (8-37) months, 75.5% of the eyes were in the ±0.50 D range and 94.4% were in the ±1.00 D range of the refractive goal. Postoperatively, the mean sphere value was -0.39 ± 0.3 and the cylinder value was -0.35 ± 0.25. Topographic evidence showed that ablation was made in the visual axis and not in the center of the cornea, thus correlating with the angle kappa. No significant complications were encountered in this small group of patients. Hyperopic LASIK utilizing the topography-guided platform of the 400 Hz Eye-Q Allegretto excimer and a femtosecond laser flap appears to be safe and effective for correction of hyperopia and/or hyperopic astigmatism. The results are impressive for refractive error correction and stability and for improvement of both uncorrected and corrected distance visual acuity.

Meta-Analysis of Wavefront-Guided vs. Wavefront-Optimized LASIK for Myopia

To detect possible differences in clinical outcomes between wavefront-guided laser in situ keratomileusis (LASIK) and wavefront-optimized LASIK for the treatment of myopia. 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. 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). 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.

Wavefront-guided epithelial laser in situ keratomileusis with mitomycin-C for myopia and myopic astigmatism: Flap-on versus flap-off technique

To compare the postoperative pain, visual recovery, and outcomes of flap-on and flap-off epithelial laser in situ keratomileusis (epi-LASIK) with mitomycin-C (MMC). Asian Eye Institute, Makati, Philippines. Case-control study. Patients with myopia up to 9.00 diopters had wavefront-guided epi-LASIK with MMC. After randomization, the epithelium was removed in 1 eye (flap off) and repositioned in the other eye (flap on). Questionnaires were used to evaluate postoperative pain and visual recovery in each eye during the first postoperative week. Visual results, refractive outcomes, contrast sensitivity, and higher-order aberrations (HOAs) were compared and analyzed. The study evaluated 48 eyes. The mean pain scores were lower and better vision was perceived in the flap-off group during the first postoperative week. One year postoperatively, the mean uncorrected distance visual acuity was -0.088 logMAR in the flap-on group and -0.036 logMAR in the flap-off group (P = .918). The spherical equivalent was within ± 0.50 D in 92% of eyes in both groups (P > .05). Forty-six percent in the flap-on group and 38% in the flap-off group gained 1 line of corrected distance visual acuity (P = .915). Contrast sensitivity tests under daytime and nighttime conditions were comparable. There was no statistically significant difference in the mean change in HOAs between groups. Wavefront-guided epi-LASIK with MMC was effective, safe, and predictable in treating myopia and myopic astigmatism. Eyes that had flap-off epi-LASIK had less pain and faster visual recovery. Visual results, refractive outcomes, contrast sensitivity, and HOAs were comparable between groups. No author has a financial or proprietary interest in any material or method mentioned.

Advanced corneal surface ablation efficacy in myopia: changes in higher order aberrations

Objective: To evaluate the change of ocular and corneal higher order aberrations (HOAs) after wavefront-guided advanced surface ablation (WF-ASA) for myopia using 4 different epithelial management techniques (AA-PRK, LASEK, Epi-PRK, and Epi-LASIK). Design: Retrospective single centre excimer database analysis. Participants: Two hundred and forty eyes equally divided between the 4 WF-ASA techniques, matched for mean and range of required spherical correction. Methods: Ocular wavefront aberrations were measured using the wavescan aberrometer and corneal aberrations were obtained from corneal topography elevation maps and calculated by ray-tracing. All data were collected preoperatively and 3 months following treatment. The aberrations were described as Zernike polynomials, and analysis focused on total HOAs and spherical aberration (SA). Results: Three months postoperatively, there was a statistically significant surgically induced increase in total HOAs and SA both for ocular and corneal analysis ( p < 0.001). There was no statistically significant difference in the induced ocular SA and HOAs between the groups, but the differences in induced corneal SA and HOAs were significant ( p = 0.010). Ocular changes in SA were weakly correlated to preoperative SA (−0.30, p < 0.001) but strongly correlated to applied spherical correction (−0.68, p < 0.001). Surgically induced corneal SA was weakly correlated to preoperative corneal SA (−0.34, p < 0.001) and applied spherical correction (−0.46, p < 0.001). Conclusions: Three months postoperatively, all procedures resulted in an increase in ocular and corneal HOAs and SA. Induced aberrations were most strongly correlated to the applied spherical power correction. Modifying the existing ablation pattern to compensate for induced HOAs might improve the outcome.

Influence of Mydriatic Eye Drops on Wavefront Sensing With the Zywave Aberrometer

To investigate a potential influence of mydriatic eye drops on wavefront sensing with the Zywave aberrometer (Technolas Perfect Vision) in terms of predicted phoropter refraction (PPR) and higher order aberrations (HOA). In this prospective study, 200 myopic eyes were measured in miosis and pharmacologically induced mydriasis with an aberrometer and automated refraction. One hundred eyes were dilated with tropicamide 0.5%+phenylephrine 2.5% eye drops (tropicamide/phenylephrine group), and the remaining 100 eyes with tropicamide 0.5% (tropicamide only group). The PPR values for a pupil diameter of 3.5 mm in miosis and mydriasis, respectively, were compared and correlated to the corresponding values of automated refraction. Changes in HOAs up to the 4th order were recorded. Predicted phoropter refraction values obtained in mydriasis were less myopic than in miosis. The spherical equivalent refraction of PPR differed by an average of 0.36 ± 0.36 diopters (D) in the tropicamide/phenylephrine group. In the tropicamide only group, the difference was 0.24 ± 0.43 D. Sphere of PPR differed by an average of 0.33 ± 0.36 D in the tropicamide/phenylephrine group and by an average of 0.24 ± 0.35 D in the tropicamide only group. Patient age had no major influence on the level of difference. Automated refraction yielded a smaller difference in spherical equivalent refraction. Changes in HOA root-mean-square were statistically significant. The cycloplegic effect of mydriatic eye drops should be taken into account when interpreting aberration measurements and planning a wavefront-guided ablation. Ideally, the use of mydriatic eye drops should be avoided to minimize refractive surprises.

Higher-Order Aberration Changes After Implantable Collamer Lens Implantation for Myopia

To investigate the changes in higher-order aberrations (HOAs) induced by implantation of Implantable Collamer Lenses (STAAR Surgical) and to explain them in relation to the surgical incision and optical properties. Prospective, observational case study. This study included 56 eyes undergoing Implantable Collamer Lens insertion for myopic correction. The corneal incision size was determined according to the amount of astigmatism. HOAs were measured before surgery and 3 months after surgery in 25 eyes having small superior incision (<3.2 mm) surgery and in 31 eyes with large superior incision (3.2 to 4.5 mm) surgery. Changes in spherical aberration, coma, trefoil, and total HOAs (third to sixth order) were analyzed. Laboratory measurements of aberration profiles of Implantable Collamer Lenses with different optical powers were performed to validate clinical measurements. In the small-incision group, trefoil (Z(3)(-3)) and spherical aberration changed significantly (P=.004). In the large-incision group, in addition to trefoil and spherical aberration, total HOA changed significantly (mean change, 0.13 ± 0.17; P=.001). Significant correlations were observed among the incision size, the astigmatism induced, and the trefoil induced. Induced trefoil showed a predominant pattern at the orientation of the incision meridian. Optical measurement of aberrations of the Implantable Collamer Lenses confirmed the postoperative negative spherical aberration. HOA changes after Implantable Collamer Lens insertion were increased trefoil and induced negative spherical aberration. These changes may be explained by the effect of the corneal incision and the negative spherical aberration in the Implantable Collamer Lens, respectively.

Clinical evaluation of laser in situ keratomileusis operation with three different ablative patterns

To evaluate the clinical outcome among three different laser in situ keratomileusis (LASIK) ablations: Q-factor customized ablation (aberration smart ablation, ASA), wave-front guided ablation (WASCA) and ablation under wave-front guiding plus iris recognition system (IR+WASCA). This prospective study comprised 96 eyes of 96 patients, and they were randomly divided into three groups: 30 patients in ASA group, 32 in WASCA group, and 34 in IR+WASCA group. There were no any statistical differences in spherical equivalent (SE), age, sex, pupil diameter, higher-order aberrations (HOA) among three groups preoperatively. Wave-front analysis was performed before and 1, 3 months after operation. All patients got an uncorrected visual acuity (UCVA) ≥ 0.8 1 and 3 months after operation. The residual SE was in ± 0.50D both at 1 and 3 months after surgery. There was no statistical difference in SE value, HOA, change of HOA, and coma aberration postoperatively among three groups. Horizontal coma (Z3¹) aberration took the majority of coma. HOA, total coma aberrations and spherical aberration increased postoperatively (P = 0.000), but without significant difference between 1 month and 3 months after surgery. That three customized LASIK are all effective, safe, accurate and stable; meanwhile WASCA may have better UCVA than the other two groups postoperatively.

Transient Increase of Higher-Order Aberrations after Lateral Rectus Recession in Children

The changes of higher-order aberrations (HOAs) after bilateral lateral rectus muscle recession were evaluated. Forty eyes of 20 children were enrolled and their wavefront information was assessed until postoperative 3 months. Even though the root mean square (RMS) of total aberration was not changed, the RMS of HOA was transiently increased at postoperative 1 week and returned to baseline level after 1 month. Among individual Zernike coefficient, secondary astigmatism, quadrafoil, secondary coma, secondary trefoil, and pentafoil showed similar tendency with the RMS of HOA. However, coma, trefoil, and spherical aberration were not changed. Regarding recession amount, it did not correlate with any Zernike coefficient. In summary, our data imply that the HOAs are transiently increased after lateral rectus recession surgery. These results are in collusion with previous reports that strabismus surgery induced transient corneal astigmatism.

Spherical aberration and higher order aberrations with Balafilcon A (PureVision) and Comfilcon A (Biofinity)

Advances in the optical design of soft contact lenses have seen certain manufacturers incorporate aspheric optics into soft lenses in an attempt to reduce spherical aberration, to provide superior visual performance. The aim of this study is to determine the on-eye differences in spherical aberration and higher order aberrations (HOA) between the Bausch and Lomb PureVision (Balafilcon A) and the CooperVision Biofinity (Comfilcon A). Twenty subjects were recruited in a prospective, randomized, unilateral study. The right eye was dilated and HOA measured with the NIDEK OPD-Scan. Each eye was fitted randomly with a -3.00D PureVision and a -3.00D Biofinity, and HOA were measured with lenses in situ across a 6 mm pupil. Paired t-tests were performed to determine HOA differences with the lenses in situ compared to baseline. Aberrometry was successfully performed on all subjects. Statistical analysis indicated no changes in spherical aberration, but changes in other HOA. With the PureVision, there were increases in Zernike terms Z (3) (1) (from 0.01 μm to -0.11 μm), Z (4) (-2) (from 0.01 μm to 0.13 μm) and Z (5) (-1) (from -0.01 μm to 0.03 μm). With the Biofinity there was an increase in Zernike term Z (3) (3) (from 0.00 μm to 0.09 μm). No statistically significant changes occurred in spherical aberration. The PureVision caused statistically significant increases in Z (3) (1) , Z (4) (-2) and Z (5) (-1) , and the Biofinity caused an increase in Z (3) (3) . Clinically significant changes (>0.1 μm) occurred with terms Z (3) (1) and Z (4) (-2) with the PureVision only.