Increase In Spherical Aberration Research Articles

Comparison of the Functional Optical Zone in Eyes With High Myopia With High Astigmatism After SMILE and FS-LASIK.

To compare the functional optical zone (FOZ) in eyes with high myopia with high astigmatism after small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). In total, 45 eyes of 45 patients with high myopia with astigmatism greater than 2.00 diopters (D) who underwent SMILE or FS-LASIK were enrolled. The FOZ, optical zone decentration, and corneal aberrations were analyzed using Scheimpflug imaging. These values were then compared between the two groups 6 months postoperatively. No postoperative complications were observed during follow-up. The mean FOZ diameter was 5.03 ± 0.31 mm for the FS-LASIK group and 5.24 ± 0.27 mm for the SMILE group (P = .007), corresponding to reductions of 1.18 ± 0.23 and 1.01 ± 0.21 mm, respectively, compared with the programmed optical zone (POZ) (P = .013). A significant difference was noted in the FOZ on the short axis between the two groups (P = .002), whereas no significant difference was observed on the long axis (P = .088). The FOZ area in the FS-LASIK and SMILE groups was 65.39 ± 6.14% and 70.09 ± 5.46% of the POZ area, respectively (P = .010). There was no significant difference in decentration between the two groups (0.29 ± 0.13 mm for the FS-LASIK group vs 0.30 ± 0.13 mm for the SMILE group, P = .798). A significant increase in spherical aberration was observed in the FS-LASIK group (P < .001). However, the induction of vertical coma was higher in the SMILE group than in the FS-LASIK group (P = .002). Eyes with high myopia with high astigmatism following SMILE achieved a larger FOZ and less spherical aberration but a larger vertical coma introduction than following FS-LASIK. [J Refract Surg. 2022;38(9):595-601.].

The Graphical Results of Myopia after Refractive Surgical Treatment by Femto2nd Optical Maser-Assisted and Epiboly’s LASEK (Eye-Surgery) have Remained Comparable.

Background: In this prospective cohort study (flap-off epi-eye-surgery), the results of femtosecond optical maser-assisted in situ keratomileusis (femto-eye-surgery) and epipolis eye-surgery refractile surgery for myopia were compared.&#x0D; Purpose: Comparison of the results of eye-surgery myopia or myopic astigmia improvement by a six- multidimensional amaris exciter optical maser and establish that both femto- eye-surgery and flap-off epi-eye-surgery are safe, effective, and predictable in Amanat eye hospital Rawalpindi. The duration of the study was July 2019- July 2021. Sample size was 400 eyes, 200 patients, 81 male and 119 female. The study was conducted after the ethical approval of the hospital ethical committee.&#x0D; Methods: Four hundred (400) eyes from 200 individuals were divided into two groups in this prospective cohort study. For femto-eye-surgery flaps, a femtosecond optical maser was used, while an epikeratome (flap-off) was used for epi-eye-surgery flaps. The researchers measured uncorrected distance graphicalacuity (u.d.v.a), corrected distance graphical acuity (c.d.v.a), visible bending (m.r), corneal asphericity (q-value), and corneal higher-order aberrations (hoas) before and after surgery. In both groups, the improvement in logmar udva following refractile surgery was statistically significant (p&lt; 0.001 for all); it was significantly higher for femto-eye-surgery 1 day and 1 week postoperatively (p &lt;0.001 for femto-eye-surgery, respectively).&#x0D; Results: Logarithm of the minimum angle of resolution (logmar) of udva after refractile surgery was statistically significant for both groups (p = 0.002); it was significantly higher for femto-eye-surgery than flap-off epi-eye-surgery (0.03 *0.06 logmar (femto-eye-surgery) and 0.54 * 0.31 logmar (flap-off epi-eye-surgery ) at 1 day postoperatively; 0.02 *0.05 logmar (f the increase in spherical aberration (z4,0) in flap-off epi-eye-surgery was reater than femto-eye- surgery : 0.626 ± 0.232 μm and 0.479 ± 0.139 μm in the front cornea; 0.556 ± 0.227 μm and 0.430 ± 0.137 μm in the total cornea (p = 0.016 and p = 0.017). There was no significant impact of the changes to the corneal hoa in the back of the eye on the corneal hoa in general.&#x0D; Conclusion: Despite the fact that femto-eye-surgery generated better early graphics results than flap-off epi-eye-surgery, there was no significant difference in the results one week following surgery.

Peripheral Refraction, Wave Front of the Eye and Visual Performance in the Correction of Myopia in Children with Bifocal Soft Contact Lenses with High Addition

Purpose: to study the effect of bifocal soft contact lens (BSCL) with an ADD of 4 diopters on peripheral refraction (PR), optical and ergonomic eye parameters in children with myopia.Patients and methods. 26 patients (52 eyes) with myopia –3.09 ± 1.13 diopters at the age of 10.04 ± 1.5 years without correction and with correction by BSCL Prima BIO Bi-focal ( Okay Vision Retail, Russia). All patients underwent a horizontal and vertical PR study on an open field autorefractometer Grand Seiko WAM-5500 (Japan), wavefront aberrations were studied on OPD-Scan III aberrometer (Nidek, Japan), contrast sensitivity under mesopic conditions were studied on a Mesotest 2 instrument (Oculus, Germany) and visual productivity was studied using test tables.Results. The visual acuity of the distance with a BSCL correction of 0.98 ± 0.04 did not differ (p = 0.26) from the maximum visual acuity corrected by spherocylindrical glasses of 0.99 ± 0.04. BSCL induces myopic defocus in all peripheral zones, with a maximum value of 15° and a sharp decrease of 30°. Peripheral myopic defocus induced by the lens at a horizontal and vertical angle of 15 degrees did not depend on the initial degree of myopia. BSCL increases the total RMS from 0.07 ± 0.02 μm to 0.19 ± 0.07 μm in the 3 mm zone (p &lt; 0.01) and from 0.27 ± 0.09 μm to 1.18 ± 0, 23 μm in the 6 mm zone (p &lt; 0.01), mainly due to an increase in spherical aberration from –0.0005 ± 0.006 μm to 0.06 ± 0.01 μm (p &lt; 0.01) and from 0.01 ± 0.09 μm to 0.58 ± 0.14 μm (p &lt; 0.01) in the 3 mm and 6 mm zones, respectively. An increase in the overall RMS in BSCL reduces the quality of eye optics and contrast sensitivity under mesopic conditions, but does not impair visual productivity.Conclusion. BSCLs with a high ADD of 4 diopters are capable of inducing significant myopic peripheral defocus due to the induction of spherical aberration, while maintaining high visual acuity and not changing ophthalmic ergonomics, which makes them a pathogenetically substantiated method for correcting myopia and preventing its progression in children and adolescents.

Analysis of I-Trace high-order aberrations induced by wavefront-optimized ablation profiles

Aim This work aimed to analyze the ocular aberrations induced by wavefront-optimized (WFO) ablation profiles using I-Trace aberrometer (ray tracing).Settings and design This is a prospective noncomparative nonrandomized clinical study that was carried out at Rooya Eye Center, Alexandria, Egypt.Patients and methods The study included 20 eyes of 10 cases that underwent laser in situ keratomileusis with WFO ablation profile. Cases were followed up at 1 and 3 months after surgery to analyze the ocular aberrations done using I-Trace Visual Functional Analyzer (ray tracing technology).Results The mean preoperative total high-order aberration was changed from 0.33±0.2 to 0.38±0.21 after 1 month (P=0.107) and became 0.35±0.15 at 3 months (P=0.265), which was statistically insignificant, with an increase of 6.074%. The mean preoperative coma was 0.27±0.17 and changed to 0.29±0.2 after 1 month (P=0.345) and became 0.32±0.22 at 3 months (P=0.107), which was statistically insignificant, with an increase of 17.6%. The mean increase in spherical aberrations was from 0.086±0.06 preoperatively to 0.18±0.15 after 1 month (P=0.018) and to 0.19±0.24 at 3 months (P=0.036), which was statistically significant, with an increase of 119.4%. The secondary astigmatism mean preoperative value was 0.06095±0.0439 and increased to 0.0787±0.0535 after 1 month (P=0.103) and became 0.1059±0.0592 at 3 months (P=0.098), which was statistically insignificant, with an increase of 73.7%. The trefoil preoperative mean was 0.18±0.13 and changed to 0.16±0.09 after 1 month (P=0.125) and became 0.15±0.07 at 3 months (P=0.251), which was statistically insignificant, with a decrease of −13.7%.Conclusion There was no significant total high-order aberrations increase after WFO ablation profile for low to moderate myopia.

Corneal Topography for Intraocular Lens Selection in Refractive Cataract Surgery

The purpose of this review is to evaluate the usefulness of corneal topography to select premium intraocular lenses (IOLs), including aspherical IOLs, toric IOLs, and multifocal IOLs, in refractive cataract surgery. Corneal topography can detect corneal regular astigmatism, corneal irregular astigmatism (higher-order aberrations [HOAs]) including spherical aberration, and corneal shape abnormalities after corneal refractive surgery. Surgeons can explain to the patients with significant corneal HOAs about its effect on postoperative visual function before surgery. Multifocal IOLs should not be selected for such eyes. For eyes with abnormal corneal shape, appropriate IOL power calculation formulae can be applied. In the case of toric IOLs, regular astigmatism and corneal HOAs should be checked. Before implanting an aspheric IOL, it is ideal to confirm spherical aberration of the cornea is not below the normal range. Because corneal HOAs, abnormal corneal shape after corneal refractive surgery, corneal regular astigmatism, and corneal spherical aberration increase postoperative refractive errors and poor vision quality with premium IOLs, corneal topography before cataract surgery is helpful in screening patients who are not appropriate candidates for premium IOLs.

Corneal wavefront aberrations and subjective quality of vision after small incision lenticule extraction.

To analyse in depth the associations between objectively measured corneal higher-order aberrations (HOAs) and subjectively perceived visual quality after small incision lenticule extraction (SMILE) as quantified with the standardized and clinically validated quality of vision (QOV) questionnaire. This cross-sectional study included patients after bilateral simultaneous SMILE for the treatment of myopia and/or myopic astigmatism with plano target refraction. Scheimpflug imaging (Pentacam HR; Oculus Optikgeräte GmbH, Wetzlar, Germany) was used to objectively quantify corneal HOAs. The standardized and validated QOV questionnaire was employed to gauge patients' subjectively perceived visual quality regarding frequency, severity and bothering effect of visual disturbances. A total of 394 eyes of 197 patients with a mean age of 32.4±7.7years and a mean postoperative follow-up of 24.3±14.1months were included. SMILE induced a statistically significant (p<0.001) increase in spherical aberration (0.074±0.131µm), coma (0.142±0.179µm), trefoil (0.018±0.067µm) as well as in total HOAs (0.191±0.176µm). Surgically induced and postoperative levels of HOA showed no correlation with the three QOV scores representative of overall visual symptom frequency, severity and bothering effect (all R2 values≤0.016). In addition, the associations between specific visual symptoms (e.g. starburst) and singular HOA terms (e.g. haloes) were very weak (all Rho values≤0.164). Small incision lenticule extraction induced significant amounts of corneal HOAs that, however, showed no clear relationships to patient-reported QOV or specific long-term visual symptoms.

Evaluation of Corneal Higher-Order Aberrations by Scheimpflug-Placido Topography in Patients with Different Refractive Errors: A Retrospective Observational Study.

Purpose To report the characteristics of anterior and posterior corneal high-order aberrations in patients with different refractive errors. Setting This study was conducted at Sohag Refractive Center, Sohag, Egypt. Design This is a retrospective observational study. Methods This study evaluated 750 patients (750 eyes) who were seeking refractive surgery. The eyes were stratified into five groups (150 eyes/group) based on refractive error: mild-to-moderate myopia, high myopia, hyperopia, simple myopic astigmatism, and simple hypermetropic astigmatism. All patients were subjected to comprehensive ophthalmological examination including corneal topography and corneal aberrometry using the Scheimpflug–Placido topography (Sirius, CSO, Italy). Results Coma aberration was statistically significant when compared in all five groups (P=0.01). It was highest in the hypermetropia group (0.26 ± 0.12 μm) but lower in the moderate myopia, high myopia, myopic astigmatism, and hypermetropic astigmatism groups. Spherical aberration was lowest in the hypermetropia group and significantly different from that in the other groups. Trefoil was statistically insignificant when all groups were compared (P=0.062) but was highest in the myopic astigmatism group (0.24 ± 0.25 μm). Total RMS peaked in the hypermetropia group (0.99 ± 0.70). Conclusions In normal corneas and regular refractive errors, the cornea-induced high-order aberration was minimal, and all types of refractive errors were associated with certain types of high-order aberrations, with a significant increase in spherical aberration in the hypermetropia group.

15-Month Visual Outcomes and Corneal Power Changes of SMILE in Treating High Myopia With Maximum Myopic Meridian Exceeding 10.00 D.

To evaluate the long-term visual and refractive outcomes, optical quality, and stability of the cornea and axial length after small incision lenticule extraction (SMILE) for the correction of high myopia with a maximum myopic meridian exceeding 10.00 diopters (D). Via a prospective cohort study, 53 eyes (53 patients) with a maximum myopic meridian exceeding 10.00 D were corrected with a VisuMax femtosecond laser (version 3.0; Carl Zeiss Meditec AG, Jena, Germany) at the Zhongshan Ophthalmic Center of Sun Yat-sen University. Refractive outcomes, aberrations, axial length, and corneal curvature were evaluated preoperatively and at 1, 3, and 15 months postoperatively. At 15 months postoperatively, the efficacy and safety indexes were 0.91 ± 0.25 and 1.15 ± 0.18, respectively. A total of 72% of eyes were within ±0.50 D and 89% were within ±1.00 D of the attempted spherical equivalent, respectively. From 1 to 15 months postoperatively, the significant regression was -0.24 ± 0.28 D (P < .001) on manifest refraction and -0.43 ± 0.54 D (P < .001) on anterior corneal curvature. In addition, a significant increase of 0.20 µm (P = .016) was observed in the spherical aberration. No significant change was observed in posterior corneal curvature (P > .999), including mean keratometry or astigmatism, or in the ocular axis length from 1 to 15 months postoperatively (26.82 ± 0.93 and 26.82 ± 0.95 mm, respectively, P > .99). SMILE had long-term safety, efficacy, and predictability when treating high myopia with a maximum myopic meridian exceeding 10.00 D. Both a manifest refraction regression of -0.24 D and a significant spherical aberration increase of 0.20 µm were observed between 1 and 15 months postoperatively, due to the increased anterior corneal curvature. [J Refract Surg. 2019;35(1):31-39.].

Spherical aberration reduction in nuclear cataracts.

To measure higher-order aberrations (HOAs) in nuclear cataracts and to investigate spherical aberration changes with nuclear cataract progression. A total of 102 eyes of older subjects (>50years) were classified based on the nuclear opalescence (NO) grading of the Lens Opacities Classification System III: Group 1 (< NO2, 35), 2 (NO2, 23), 3 (NO3, 23), and 4 (≥ NO 4:21 eyes). Wave front measurements were performed with a Hartmann-Shack aberrometer. To investigate lenticular spherical aberration, HOAs were examined in 28 eyes before and after phacoemulsification, followed by insertion of an aberration-free intraocular lens. The relationship between lens opacity grade and ocular and lenticular spherical aberrations were investigated. Mean spherical aberrations in groups 1, 2, 3, and 4 were 0.25 ± 0.10, 0.16 ± 0.13, 0.12 ± 0.15, and 0.10 ± 0.20μm, respectively, and showed a significant difference with nuclear opacity grading (p = 0.001). The spherical aberration showed negative associations with nuclear opacity grading (r = -0.408, p < 0.001). The predominant change in HOAs after phacoemulsification was an increase in spherical aberration, and 86% of lenticular spherical aberrations were presumed to have negative values. The lenticular spherical aberration was negatively correlated with nuclear opacity severity (r = -0.409, p = 0.031). Ocular spherical aberration decreases with the progression of nuclear cataracts due to the negative correlation between lenticular spherical aberration and nuclear opacity severity.

A model of field and spherical aberration in soft/hard edge solenoid magnets

A solenoid magnetic field model is presented that describes the on axis field by a parameter of its hard edginess and axial half-width at half-maximum field, which universally define its spherical aberration without solving the ray equation. The model shows an increase in spherical aberration from real soft edge fields to hard edge models, as used in beam tracking. It compares well with existing field models. It simply and accurately finds the spherical aberration in many types of solenoids.

Laser-Assisted In Situ Keratomileusis in High Mixed Astigmatism With Optimized, Fast-Repetition and Cyclotorsion Control Excimer Laser

To evaluate the visual refractive and aberrometric outcomes of laser-assisted in situ keratomileusis (LASIK) surgery for the correction of high mixed astigmatism using a new-generation excimer laser and optimized aspherical profiles. Retrospective interventional case series. Fifty-two eyes of 36 patients (21-53 years) with primary mixed astigmatism over 3.0 diopters (D) were included. All cases underwent LASIK surgery using the sixth-generation excimer laser Amaris with cyclotorsion control and a femtosecond platform for flap creation. Visual, refractive, corneal topographic, and aberrometric outcomes were evaluated during a 3-month follow-up. Refractive astigmatic changes were analyzed by Alpins method. A significant reduction of refractive sphere and cylinder was observed 3 months postoperatively (P = .001), with an associated improvement of uncorrected distance visual acuity (P = .001). Best-corrected distance visual acuity (CDVA) remained unchanged in 31 eyes (59.6%), while 3 eyes (5.76%) lost 2 lines of CDVA. Fourteen eyes (26.9%) had spherical equivalent (SE) within ±0.5 D of emmetropia and 34 (65.3%) had SE within ±1.0 D of emmetropia. No significant difference was observed when comparing surgically induced and target astigmatism. A significant induction of higher-order aberration attributable to increase of spherical aberration was found (P = .003). Seven eyes (13.4%) required retreatment. LASIK for primary high mixed astigmatism using optimized aspherical profiles and a fast-repetition-rate excimer laser with cyclotorsion control is a safe, effective, and predictable procedure. Induction of higher-order aberrations is still present in the correction of the refraction error of the magnitude included in this study.

Effects of advanced surface ablations and intralase femtosecond LASIK on higher order aberrations and visual acuity outcome

Background/aims To study the changes in wavefront (ocular) and corneal higher order aberrations (HOAs) and visual acuity (VA) outcome following wavefront-guided advanced surface ablation (ASA) techniques and intralase femtosecond LASIK (iLASIK) in myopia treatment. Methods Ocular aberration and corneal topography of 240 eyes in the ASA techniques (this was equally divided into a flap-on group where the epithelial flap was preserved and reapplied to the photoablated stromal bed and a flap-off group when the epithelial flap was discarded during the procedure), and 138 eyes in the iLASIK group were obtained before and 3 months following treatment. The correlation of aberrations with best spectacle-corrected visual acuity was analyzed. Results At 3 months, there was statistically significant ( P < 0.001) surgically induced increase in spherical aberration (SA) in each of the techniques for both ocular and corneal analysis. iLASIK induced significantly less ocular and corneal HOAs ( P < 0.001). The mean manifest refractive spherical equivalent was closer to attempted correction compared to other groups ( P < 0.001). Eighty-three eyes (70%) of flap-on, 80 (67%) flap-off and 94 eyes (68%) in the iLASIK group achieved 20/20 uncorrected VA. Fifteen eyes (11%) accomplished 20/12.5 or better in iLASIK compared to 4 (3%) for flap-on and 7 (6%) for flap-off ASA group. Only the flap-off treatment showed a consistent correlation between the corrected aberrations and visual performance. Conclusion At 3 months, all procedures resulted in a significant increase in HOAs and SA. All had comparable 20/20 VA and 11% of iLASIK patients achieved 20/12.5 or better level.

Influence of spherical intraocular lens implantation and conventional laser in situ keratomileusis on peripheral ocular aberrations

To measure the effect of spherical intraocular lens (IOL) implantation and conventional myopic laser in situ keratomileusis (LASIK) on peripheral ocular aberrations. Visual and Ophthalmic Optics Laboratory, School of Optometry, and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia. Peripheral aberrations were measured using a modified commercial Hartmann-Shack aberrometer across 42 degrees x 32 degrees of the central visual field after spherical IOL implantation and after conventional LASIK for myopia. The results were compared with those in an age-matched emmetropic group and an age-matched myopic control group, respectively. The rate of quadratic change in spherical equivalent (SE) refraction, higher-order root-mean-square (RMS) aberrations, and total RMS aberrations across the visual field was greater and the amount of spherical aberration higher in the IOL group than in the emmetropic control group. However, coma trends were similar in the 2 groups. The rate of quadratic change in SE refraction, higher-order RMS aberrations, and total RMS aberrations was greater across the field and the amount of spherical aberration higher in the LASIK group than in the myopic control group. The trend in coma across the field in the LASIK group was opposite that in the other groups. Spherical IOL implantation and conventional myopic LASIK increased ocular peripheral aberrations, causing a significant increase in spherical aberration across the visual field. Laser in situ keratomileusis reversed the sign of the rate of change in coma across the field relative to that in the other groups. No author has a financial or proprietary interest in any material or method mentioned.

Comparison of Postoperative Wavefront Aberrations After NIDEK CXIII Optimized Aspheric Transition Zone Treatment and OPD-guided Custom Aspheric Treatment

To compare higher order aberrations of aspheric or wavefront-guided myopic LASIK. This was a prospective, randomized study of a myopic LASIK cohort that was subdivided into two groups; 12 eyes were treated with the optimized aspheric transition zone algorithm (OATz group) and 11 eyes were treated with wavefront-guided optimized path difference custom aspheric treatment (OPDCAT group). Corneal asphericity and higher order aberrations root-mean-square were compared between groups before, 1 month, and 3 months after LASIK. Student t test was used to assess differences between groups. P<.05 was considered statistically significant. At 3 months postoperatively, all eyes in both groups had spherical equivalent refraction of +/-0.50 diopters (D). Mean higher order aberration increased by 0.18 microm postoperatively in the OATz group (P<.05) and decreased by 0.04 microm in the OPDCAT group (P=.819). A statistically significant increase in spherical aberration was noted in the OATz group only (P<.05). Asphericity showed a statistically significant difference between the two groups postoperatively (P<.05). There was a greated tendency for increased higher order aberrations in eyes with <0.30 microm of higher order aberrations preoperatively in the OPDCAT group. The reverse tendency was observed in the OATz group. OPDCAT induced minimal changes in spherical aberration due to lower changes in corneal asphericity compared to the OATz group. Eyes with <0.30 microm of higher order aberrations preoperatively are likely better candidates for the OATz algorithm than OPDCAT.

Study of ocular aberrations with age

Aging has various effects on visual system. Vision deteriorate, contrast sensitivity decreases and ocular aberrations apparently make the optical quality worse across the years. To prospective evaluate ocular aberrations along the ages. Three hundred and fifteen patients were examined, 155 were male (39.36%) and 160 were female (60.63%). Ages ranged from 5 to 64 year-old, the study was performed from February to November, 2004. Patients were divided into 4 age-groups according to IBGE (Instituto Brasileiro de Geografia e Estatística) classification: 68 patients from 5 to 14 year-old, 55 patients from 15 to 24 year-old, 116 from 25 to 44 year-old and 76 from 45 to 67 year-old. All patients had the following characteristics: best corrected visual acuity > 20/25, emmetropia or spherical equivalent < 3.50 SD, refractive astigmatism < 1.75 CD on cycloplegic refraction, normal ophthalmologic exam and no previous ocular surgeries. This protocol was approved by Federal University of São Paulo Institutional Review Board. Total optical aberrations were measured by H-S sensor LadarWave Custom Cornea Wavefront System (Alcon Laboratories Inc, Orlando, FLA, USA) and were statistically analysed. Corneal aberrations were calculated using CT-View software Version 6.89 (Sarver and Associates, Celebration, FL, USA). Lens aberrations were calculated by subtraction. High-order (0.32 e 0.48 microm) and ocular spherical aberrations (0.02 e 0.26 microm) increased respectively in child and middle age groups. High order (0.27 microm) and corneal spherical aberrations (0.05 microm) did not show changes with age. Lens showed a statistically significant spherical aberration increase (from -0.02 to 0.22 microm). Vertical (from 0.10 to -0.07 microm) and horizontal coma (from 0.01 to -0.12 microm) presented progressively negative values with aging. High-order and spherical aberrations increased with age due to lens contribution. The cornea did not affect significantly changes observed on ocular aberrations.

Long-term Follow-up of Orthokeratology Corneal Reshaping Using Wavefront Aberrometry and Contrast Sensitivity

To evaluate changes in ocular wavefront aberrations and contrast sensitivity during 1-year follow-up of overnight orthokeratology. Prospective study of 26 eyes that underwent orthokeratology with the BE lens design. Wavefront measurements were analyzed at baseline and after 1, 8, 30, 90, 180, and 365 nights of orthokeratology for a 6.5-mm pupil diameter. Contrast sensitivity 1 year after orthokeratology was compared to the baseline value under photopic conditions and mesopic conditions, with and without glare, in the spatial frequencies of 1.5, 3, 6, 12, and 18 cycles/degree. A P value of less than 0.05 was statistically significant. Higher-order aberration root-mean-square (HOA-RMS) increased statistically significantly from 0.41 +/- 0.12 microm to 1.04 +/- 0.32 microm up to night 8. Defocus (Z4) decreased until night 8 and then stabilized. Astigmatism (Z3 + Z5) did not change. There was a sevenfold increase in spherical aberration (Z12) until night 8, which subsequently remained unchanged (P<0.001). Coma (Z7 + Z8) increased until night 90 and then stabilized (P<0.001). Other Zernike modes showed stability at night 1, with the exception of quadrafoil (Z14) (P=0.048). Mesopic contrast sensitivity, with and without glare, at 18 cycles/degree, decreased but failed to reach statistical significance (P=0.922 and P=0.827, respectively). Most optical aberrations stabilized within the first week after beginning orthokeratology with BE lens. There was not a statistically significant reduction in contrast sensitivity 1 year after treatment.

Long-Term Results of Presbyopic Corneal Surface Ablation with Eximer Laser

Purpose: To evaluate the efficacy, safety, and subjective symptoms of patients who underwent presbyopic corneal surface ablation. Methods: Excimer laser surgery with MEL80 for refractive errors and presbyopia was performed on 128 eyes of 67 patients. Uncorrected and best-corrected visual acuity, distance-corrected near-visual acuity, spectacle near-addition for Jaeger 1, depth of focus, spherical aberration, and subjective symptoms were evaluated before surgery and 1 year after surgery. Results: This study consisted of a myopia group (56 eyes), an emmetropia group (spherical equivalent ≤ ±0.75D, 19 eyes), and a hyperopia group (53 eyes). Presbyopic corneal ablation improved distance and near uncorrected visual acuity, and distance-corrected near visual acuity at postoperative 12 months. There was no significant change in best-corrected visual acuity but there was a significant decrease in the emmetropia only group. Useful near visual acuity (≥20/40) was found in 96 eyes (75%) and spectacle near addition for Jaeger 1 decreased. Our results showed a significant increase of spherical aberration (from -0.19 µm to 0.11 µm) and depth of focus (from 1.45D to 1.69D). A significant positive correlation was found between spherical aberration and uncorrected far and near visual acuity and depth of focus. Loss of two lines of best corrected visual acuity occurred in 11 eyes (8.5%) at far vision and in 7 eyes (5.5%) at near vision. In general, patient satisfaction was good. Conclusions: Presbyopic corneal ablation with MEL80 showed good distant and near visual results and a wide depth of focus induced by increased spherical aberration.

Prospective randomized trial of wavefront-guided laser in situ keratomileusis with the CustomCornea and CustomVue laser systems

To compare visual function, safety, and higher-order aberrations (HOAs) after wavefront-guided laser in situ keratomileusis (LASIK) with the LadarVision CustomCornea (Alcon Laboratories, Inc.) and Star S4 CustomVue (Visx) laser systems. John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. Seventy-eight eyes of 39 patients with myopia with or without astigmatism were randomized for LASIK treatment in 1 eye with the CustomCornea laser; the other eye was treated with the CustomVue laser. Patients were followed for 6 months after surgery. The primary outcome measures were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, and changes in HOAs. At 6 months, the mean logarithm of the minimum angle of resolution (logMAR) UCVA was -0.0135 +/- 0.07 (SD) in the CustomVue group and 0.0417 +/- 0.12 in the CustomCornea group (P = .023). Eighty-eight percent of eyes in the CustomVue group had 20/20 or better UCVA compared with 67% in the CustomCornea group (P<.02). At 6 months, 91% of eyes in the CustomVue group and 79% in the CustomCornea group were within +/-0.50 diopter (D) of emmetropia (P<.1); 88% and 50%, respectively, were within +/-0.25 D (P<.001). Both platforms led to a small increase in total HOAs. The CustomVue system reduced trefoil and induced less of an increase in total HOAs, whereas the CustomCornea platform increased trefoil but induced less of an increase in spherical aberrations and coma. Both laser systems were effective, safe, and predictable. Wavefront-guided LASIK with the CustomVue system resulted in better visual acuity, with more eyes having 20/20 acuity than in the CustomCornea group.

Analysis of refractive errors in the eyes of young Indians

The refractive errors of normal, healthy eyes were measured using an indigenously developed Shack–Hartmann aberrometer. Measurement was made in both right and left eyes after dilation for a 6 mm pupil size. The power vector method was used to represent the sphero-cylindrical errors. Analysis was done for astigmatism with the rule, oblique astigmatism and defocus between the right and left eyes of the subjects, which showed a negative, positive and zero correlation respectively. No correlation could be detected for RMS values between right and left eyes, though Zernike between right and left showed bilateral symmetry in our subjects. It was found that with an increase of spherical aberration, defocus decreased slightly. The validity and repeatability of our Shack–Hartmann aberrometry in measuring the refractive error was analysed and repeatability coefficient calculated. Optimal correction for greater retinal image quality has been discussed and far-point vergence for detecting the point of maximum retinal image quality is suggested.

Changes in Spherical Aberration after Lens Refilling with a Silicone Oil

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. 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. 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. 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.