Symmetric offset versus asymmetric offset ablation with transepithelial refractive keratectomy.

BACKGROUND: In eyes with hyperopia, astigmatism, and mixed astigmatism Transepithelial photorefractive keratectomy (TransPRK) is a modality of surface ablation surgery. We center on the corneal vertex for all our treatments (all have an offset to the center of the pupil) and wanted to compare the visual results of symmetrical profile treatments versus asymmetrical profile treatments (the center of the treatment on the vertex and the boundaries with the pupil center) using TransPRK as corneal refractive surgery. METHODS: We retrospectively analyzed two consecutive groups of eyes treated with TransPRK in the Aurelios Augenlaserzentrum Recklinghausen: 47 eyes treated with symmetrical offset and 51 eyes treated with asymmetrical offset. The intergroup comparisons were assessed using unpaired Student's T-tests, whereas preoperative to postoperative changes were assessed using paired Student's T-tests. RESULTS: Refractive outcomes were good for both groups. 83 and 88% of eyes were within the spherical equivalent of 0.5 D from the target in the symmetric and asymmetric offset groups, respectively. 85 and 84% of eyes had a postoperative astigmatism of 0.5 D or lower in the symmetric and asymmetric offset groups, respectively. CONCLUSION: We have not found a significant difference in the refractive outcomes between the symmetric group and the asymmetric group of eyes treated both with TransPRK for preoperatively hyperopic or mixed astigmatism.

[TransPRK in general anesthesia-An alternative for anxious patients]. / TransPRK in Allgemeinanästhesie ­ eine Alternative für Angstpatienten.

OBJECTIVE: The aim was to analyze and compare the refractive results of anxious patients treated with transepithelial photorefractive keratectomy (TransPRK) while under general anesthesia (ITN) versus patients treated under local anesthesia (TRO). MATERIAL AND METHODS: The TransPRK treatment was performed with the AMARIS 1050 RS laser (SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany) in a group of patients with ITN and a group of patients, treated as usual with TRO. The method used an aspheric aberration neutral ablation profile, as well as SmartPulse technology and 7D eyetracking. In ITN propofol and rocuronium were injected intravenously. The artificial respiration was via a resuscitation bag after intubation with a laryngeal mask. To achieve pain insensitivity in the group of patients in TRO three drops of Conjucain Edo 0.4% were instilled at intervals of a few minutes. Follow-up examinations were performed after 1 and 4 days and after 1 and 3 months. RESULTS: A total of 35 consecutive TransPRK laser treatments under ITN were retrospectively compared with a group of 699 eyes treated with TransPRK under TRO in the period from February 2017 to December 2021. The preoperative sphere had a range of -5.50 to -1.0 dpt, the average cylinder was 1.19 dpt and cylinders were treated up to 4.75 dpt. The results after 3 months follow-up showed a predictability of 100% eyes within the target correction of less than 0.5 dpt in ITN and in TRO 97%. The astigmatic correction showed 91% of eyes in ITN with less than 0.5 dpt and an angle of error of 83% within ±5°. In TRO 96% of eyes showed astigmatic correction with less than 0.5 dpt and an angle of error of 77% within ±5°. After 3 months 83% of eyes treated in ITN reached a visual acuity of 1.0 or more and 84% of eyes treated in TRO. CONCLUSION: The TransPRK performed in ITN led to equal refractive results than when treated as usual in TRO. For anxious patients there is the possibility of laser vision correction in ITN. Because of shorter treatment time and accordingly shorter time under general anesthesia, TransPRK is an advantage for LASIK surgery.

Refractive Effect of Epithelial Remodelling in Myopia after Transepithelial Photorefractive Keratectomy.

(1) Introduction: We analysed epithelial changes after the treatment of moderate myopia with transepithelial photorefractive keratectomy. (2) Materials and Methods: We used optical coherence tomography data and analysed changes in the stroma and epithelium after ablation. We aimed to ascertain how much epithelium hyperplasia occurred after TransPRK; for this, we used data from 50 eyes treated with TransPRK with the AMARIS 1050 Hz, with a minimum follow-up of 4 months. (3) Results: The measured epithelial changes corresponded to a less than 0.1 ± 0.2D of spherical effect, less than 0.2 ± 0.2D of astigmatic effect, and less than 0.5 ± 0.2D of comatic effect. (4) Conclusions: The changes in epithelial thickness after aberration-neutral transepithelial photorefractive keratectomy for moderate myopia were very small, indicating a low level of epithelial hyperplasia without resembling a regression-inducing lentoid.

Does low infusion pressure microincision cataract surgery (LIPMICS) reduce frequency of post-occlusion breaks?

Objective: To compare the number of surge events and efficacy of phacoemulsification using a near-physiological intraocular pressure (IOP) setting and a standard IOP setting. Materials and methods: The surgical data of patients who underwent phacoemulsification with IOL implantation using the CENTURION Vision System's Active Fluidics setting and Active Sentry Handpiece (Alcon Laboratories, USA) were analyzed. Results: The study included 181 patients (204 eyes). In Group 1, the IOP was set at 20 mmHg (n=102, 50%), and in Group 2, the IOP was set at 60 mmHg (n=102, 50%). Total case time was significantly lower (p=.036) in Group 1 (0:03:17.20 ± 0:00:34.55 vs. 0:03:28.71 ± 0:00:43.03). There was no statistically significant difference between the mean cumulative dissipated energy (CDE) (7.06 ± 3.20 vs. 7.59 ± 3.26) and mean ultrasound (UJS) time (0:00:36 ± 0:00:12 vs. 0:00:38 ± 0:00:13) between the two groups (p=0.24 and p=0.31, respectively). Active sentry (AS) engaged less often (p<0.001) in Group 1. There was no statistically significant correlation between the CDE and AS activation in Group 1 (p=0.96). A strong statistically significant correlation between the CDE and AS activation (p<0.0001, r=0.61, CI (0.47 to 0.72)) was observed in group 2. Conclusion: During phacoemulsification, surge events are more likely to occur when operating at high IOP settings. Abbreviations: LIPMICS = low infusion pressure microincision cataract surgery, IOP = intraocular pressure, CDE = cumulative dissipated energy, UJS = mean ultrasound time, AS = Active sentry, LOCS = Lens Opacities Classification System, NO = nuclear opalescence, AFR = aspiration flow rate.

Transepithelial Photorefractive Keratektomy after a Clear Lens Exchange.

PURPOSE: We evaluated the refractive visual outcomes and efficacy of Transepithelial Photorefractive Keratectomy (TransPRK) using Smart Pulse Technology with static and dynamic cyclotorsion and the AMARIS 1050 Hz RS laser platform from Schwind in the eyes after a refractive lens exchange. Setting/Venue: Aurelios Augenlaserzentrum, Recklinghausen. METHODS: We retrospectively evaluated the data of 552 consecutive eyes treated with refractive lens exchange between 2016 and 2019. A total of 47 eyes (8.5%) required a touch up after the clear lens exchange. From 43 eyes of 43 patients, we obtained a minimum follow up of 3 months. In all cases, we performed a TransPRK with a minimum optical zone of 7.2 mm, centering the ablation on the vertex of the cornea. RESULTS: The average age of the treated eyes was 57 years old, with a range between 48 and 68 years. The mean treated sphere was 0.42 diopters (D), with a range between -1.0 and +1.75 D. The mean astigmatism was 1.06 D. Postoperatively, after laser vision correction, we reduced the sphere to a mean of 0.11 D (range -0.5 to +0.75 D), and, postoperatively, the mean astigmatism was 0.25 D (range -0.75 to 0 D). The predictability for a spheric equivalent (SEQ) of 0.5 D was 91%, and for 1 D it was 100% of the cases. No eye lost more than one Snellen line. CONCLUSIONS: TransPRK with smart pulse was predictable for correcting ametropia after Clear Lens Surgery.

TransPRK treatment for residual refractive error and induced aberrations in eye undergone SMILE treatment.

In this case report, we propose to correct refractive errors after SMILE a refractive lenticule surgery technique with transepithelial Photorefractive keratectomy (TransPRK).The advantage of this technique is that the measured aberrations with topography o the Cornea are also treated on the Surface of the Cornea.

High-speed recording of thermal load during laser trans-epithelial corneal refractive surgery using a 750Hz ablation system.

PURPOSE: To evaluate the temperature rise of human cornea during trans-epithelial photorefractive keratectomy (trans-PRK) with a 750Hz excimer laser employing Intelligent Thermal Effect Control (ITEC) software. METHODS: In this observational case series, trans-PRK ablation was performed on 5 eyes of 3 patients using an aspheric profile of a 750Hz excimer laser system. A high-resolution infrared camera with a frame-rate of 350 images per second was used to determine the corneal surface temperature. Images were taken sequentially, starting a few seconds prior to and ending a few seconds after the ablation. The maximum temperature of any pixel of a given image were recorded and graphed against time. RESULTS: The baseline ocular surface temperature, immediately prior to the beginning of excimer laser, ranged from 32 to 34.9°C. The maximum ocular surface temperature until the epithelium was ablated ranged from 35.2 to 39.7°C. The maximum ocular surface temperature during stromal ablation with high and low fluence laser ranged from 32.9 to 36.5 and from 34.4 to 37.7°C respectively. CONCLUSION: The ITEC software is effective in controlling the maximum temperature rise during laser ablation in the extremely challenging situation of trans-PRK involving high ablation volumes of almost 6000nl, potentially improving the outcomes. The ITEC system limited the maximum temperature to 39.7°C in the epithelium, and 37.7°C in the stroma. The epithelial temperature was always higher than stromal temperature (regardless of high or low fluence irradiation). Safety limit of 40°C found in the literature was never reached.

Transepithelial Photorefractive Keratectomy in Moderate to High Astigmatism With a Non-wavefront-Guided Aberration-Neutral Ablation Profile.

PURPOSE: To evaluate the outcomes of transepithelial photorefractive keratectomy (PRK) in moderate to high astigmatism with a non-wavefront-guided aberration-neutral ablation profile using SmartPulse allocation. METHODS: In this retrospective study, myopic patients with a preoperative cylinder of 2.00 diopters (D) or greater were analyzed at 3 months of follow-up. Transepithelial PRK treatments were performed in each patient with the Amaris 1050RS laser (SCHWIND eye-tech-solutions, Kleinostheim, Germany) creating aspheric ablation profiles by applying a SmartPulse allocation. Standard examinations and wavefront analyses were included for low and high ocular residual astigmatism subgroups. RESULTS: Fifty-eight eyes (44 patients) were included in the cohort. The eyes were divided into separate ocular residual astigmatism subgroups: 17 eyes presented with less than 0.50 D (low ocular residual astigmatism) and 24 eyes with greater than 0.75 D (high ocular residual astigmatism). The mean refractive cylinder in the entire cohort was 2.84 ± 0.86 D preoperatively and 0.40 ± 0.39 D postoperatively, with 81% of the eyes within 0.75 D of the target astigmatism. At 3 months of follow-up, significant improvement (P < .05) was seen in terms of sphere, cylinder, spherical equivalent, and uncorrected (UDVA) and corrected (CDVA) distance visual acuity. CDVA improved in 40% of eyes and 3% of eyes lost one line of CDVA. No clinically relevant changes were seen in higher order aberrations. The refractive changes showed an excellent match with the keratometric changes. The difference between the low and high ocular residual astigmatism subgroups was not significant except for the change of Snellen lines of CDVA (P < .05). CONCLUSIONS: Transepithelial PRK using a non-wavefront-guided aberration-neutral ablation profile performed by applying SmartPulse allocation yielded excellent visual outcomes. The preoperative astigmatism was reduced to subclinical values. Both subgroups were effective in terms of UDVA, CDVA, spherical and astigmatic correction, and preserving higher order aberrations. However, the low ocular residual astigmatism subgroup was slightly more prone to gain lines of CDVA. [J Refract Surg. 2018;34(7):466-474.].

Corneal functional optical zone under monocular and binocular assessment.

BACKGROUND: In this retrospective randomized case series, we compared bilateral symmetry between OD and OS eyes, intercorneal differences and Functional Optical Zone (FOZ) of the corneal aberrations. METHODS: Sixty-seven normal subjects (with no ocular pathology) who never had any ocular surgery were bilaterally evaluated at Augenzentrum Recklinghausen (Germany). In all cases, standard examinations and corneal wavefront topography (OPTIKON Scout) were performed. The OD/OS bilateral symmetry was evaluated for corneal wavefront aberrations, and FOZ-values were evaluated from the Root-Mean-Square (RMS) of High-Order Wavefront-Aberration (HOWAb). Moreover, correlations of FOZ, spherical equivalent (SE), astigmatism power, and cardinal and oblique astigmatism for binocular vs. monocular, and binocular vs. intercorneal differences were analyzed. RESULTS: Mean FOZ was 6.56 ± 1.13 mm monocularly, 6.97 ± 1.34 mm binocularly, and 7.64 ± 1.30 mm intercorneal difference, with all strongly positively correlated, showing that the diameter of glare-free vision is larger in binocular than monocular conditions. Mean SE was 0.78 ± 1.30 D, and the mean astigmatism power (magnitude) was 0.46 ± 0.52 D binocularly. The corresponding monocular values for these metrics were 0.78 ± 1.30 D and 0.53 ± 0.53 D respectively. SE, astigmatism magnitude, cardinal astigmatism component, and FOZ showed a strong correlation and even symmetry; and oblique astigmatism component showed odd symmetry indicating Enantiomorphism between the left and right eye. CONCLUSIONS: These results confirm OD-vs.-OS bilateral symmetry (which influences binocular summation) of HOWAb, FOZ, defocus, astigmatism power, and cardinal and oblique astigmatism. Binocular Functional Optical Zone calculated from corneal wavefront aberrations can be used to optimize refractive surgery design.

The art of nomograms.

BACKGROUND: To retrospectively analyse strategies for adjusting refractive surgery plans with reference to the preoperative manifest refraction. METHODS: We constructed seven nomograms based on the refractive outcomes (sphere, cylinder, axis [SCA]) of 150 consecutive eyes treated with laser in situ keratomileusis for myopic astigmatism. We limited the initial data to the SCA of the manifest refraction. All nomograms were based on the strategy: if for x diopters (D) of attempted metric, y D is achieved; we can reverse this sentence and state for achieving y D of change in the metric, x D will be planned. The effects of the use of plus or minus astigmatism notation, spherical equivalent, sphere, principal meridians notation, cardinal and oblique astigmatism, and astigmatic axis were incorporated. RESULTS: All nomograms detected subtle differences in the spherical component (p < 0.0001). Nomograms 5 and 7 (using power vectors) and 6 (considering axis shifts) detected significant astigmatic differences (nomogram 5, p < 0.001; nomogram 6, p < 0.05; nomogram 7, p < 0.005 for cardinal astigmatism, p = 0.1 for oblique astigmatism). We observed mild clinically relevant differences (~ 0.5 D) in sphere or astigmatism among the nomograms; differences of ~ 0.25 D in the proposals for sphere or cylinder were not uncommon. All nomograms suggested minor improvements versus actual observed outcomes, with no clinically relevant differences among them. CONCLUSIONS: All nomograms anticipated minor improvements versus actual observed outcomes without clinically relevant differences among them. The minimal uncertainties in determining the manifest refraction (~ 0.6 D) are the major limitation to improving the accuracy of refractive surgery nomograms.

Laser in situ keratomileusis for high hyperopia with corneal vertex centration and asymmetric offset.

PURPOSE: To investigate refractive outcomes and induction of corneal higher order aberrations (HOA) in eyes that underwent laser-assisted in situ keratomileusis (LASIK) for high hyperopia correction using an aberration neutral profile with corneal vertex centration and asymmetric offset. METHODS: A total of 24 consecutive patients (38 eyes) who underwent LASIK by one surgeon using AMARIS 750S excimer laser and a Carriazo-Pendular microkeratome for flap creation were retrospectively analyzed. Eyes targeted for plano and with correction in the maximum hyperopic meridian strictly higher than +4D were included in the retrospective analysis. Patients were reviewed at 1, 3, and 6 months postoperatively. Postoperative monocular corrected distance visual acuity (CDVA) and uncorrected distance visual acuity (UDVA), manifest refraction, and corneal wavefront aberrations were compared with respective preoperative metrics. RESULTS: Mean preoperative spherical equivalent and refractive astigmatism was +4.07 ± 0.90 D and 1.37 ± 1.26 D, respectively, reducing to +0.28 ± 0.58D (p<0.0001) and 0.49 ± 0.47 D (p = 0.0001) at the last postoperative visit. Six months postoperatively, 78% of eyes achieved a UDVA of 20/25 or better. No eye lost more than 2 Snellen lines of CDVA at any follow-up. There was a statistically significant induction of vertical trefoil (+0.104 ± 0.299 µm, p<0.05), vertical coma (-0.181 ± 0.463 µm, p<0.01), horizontal coma (+0.198 ± 0.663 µm, p<0.05), spherical aberration (-0.324 ± 0.281 µm, p<0.0001), secondary vertical trefoil (+0.018 ± 0.044 µm, p<0.01), and secondary horizontal coma (+0.026 ± 0.083 µm, p<0.05). CONCLUSIONS: Laser-assisted in situ keratomileusis for high hyperopia using corneal vertex centration with asymmetric offset results in significant improvement in refraction and visual acuity although affected by significant induction of some higher order aberrations.

LASIK for Hyperopia Using an Aberration-Neutral Profile With an Asymmetric Offset Centration.

PURPOSE: To investigate refractive outcomes and induction of corneal higher order aberrations (HOAs) in eyes with large pupil to corneal vertex offset that underwent LASIK for hyperopia using an aberration-neutral profile with corneal vertex centration and asymmetric offset. METHODS: In this retrospective consecutive review, 26 patients (46 eyes) who underwent LASIK performed by one surgeon using the AMARIS 750S excimer laser platform and Carriazo-Pendular microkeratome (both from SCHWIND eye-tech-solutions, Kleinostheim, Germany) for flap creation were retrospectively analyzed. Only eyes targeted for plano and with a pupil to corneal vertex offset greater than 200 µm were included. The preoperative metrics were correlated with the outcomes at 3 and 6 months postoperatively. RESULTS: The mean spherical equivalent was +3.43 ± 1.30 diopters (D) preoperatively and +0.21 ± 0.61 D at last postoperative visit (P < .0001). Mean refractive astigmatism was 1.09 ± 1.06 D preoperatively, and 0.39 ± 0.43 D at last postoperative visit. Postoperative uncorrected distance visual acuity of 20/25 or better was achieved in 74%, 65%, and 79% of eyes at 1, 3, and 6 months, respectively, compared to 85% corrected distance visual acuity of 20/25 or better preoperatively. Statistically significant correlation was observed between preoperative and postoperative aberration values for vertical trefoil (P < .0005), vertical coma (P < .0005), oblique tetrafoil (P < .0001), secondary cardinal astigmatism (P < .05), cardinal tetrafoil (P < .05), and secondary vertical trefoil (P < .05). CONCLUSIONS: LASIK for high levels of hyperopia using corneal vertex centration with asymmetric offset was safe and predictable. Maintaining postoperative keratometry less than 49.00 D after hyperopic LASIK and centering on corneal vertex may reduce the induction of coma compared to other profiles or centration strategies.

Thermodynamic measurement after cooling the cornea with intact epithelium and lid manipulation.

PURPOSE: To characterize the rate of change of ocular surface temperature (OST) under lid manipulation after cooling the intact cornea with balanced salt solution (BSS). METHODS: In a patient for refractive surgery, prior to the ablation, the temperature of the cornea was continuously recorded with a high speed infrared (350Hz) camera. Two millilitre of chilled BSS with a temperature of 8.6°Celsius (°C) was instilled for about 3s. Using exponential functions, the three contributions have been determined, subjacent corneal layers, environment, and chilled BSS. RESULTS: The mean temperature of the cornea preoperatively was 34.5°C. After applying the chilled BSS the temperature decreased about 14°C down to an OST of 20°C and the time needed afterwards to get the normal (OST) temperature of about 30°C was 40s. Due to the inserted speculum and missing blink, OST did not reach the original OST of 34.5°C and faded at about 32.5°C. According to our best fitted model, absolute value of each contributing component was 31.4°C (subjacent corneal layers), 26.8°C (environment) and 8.6°C (BSS). CONCLUSIONS: Applying chilled BSS to the cornea quickly reduces the temperature of the cornea with a thermal relaxation time of 3s and a amplitude decrease of 8.6°C. This together with a relaxation time of 7s for subjacent corneal layers, and 184s for environment after instillation of BSS combined with a well-controlled environment provides a period of 40s of corneal temperature below baseline, which may be of clinical benefit when applying chilled BSS immediately before or immediately after ablation.

Influence of stromal refractive index and hydration on corneal laser refractive surgery.

PURPOSE: To evaluate the influence of the stromal refractive index and hydration on postoperative outcomes in eyes that had corneal laser refractive surgery using the Amaris laser system. SETTING: Augenzentrum Recklinghausen, Recklinghausen, Germany. DESIGN: Comparative case series. METHODS: At the 6-month follow-up, right eyes were retrospectively analyzed. The effect of the stromal refractive index and hydration on refractive outcomes was assessed using univariate linear and multilinear correlations. RESULTS: Sixty eyes were analyzed. Univariate linear analyses showed that the stromal refractive index and hydration were correlated with the thickness of the preoperative exposed stroma and was statistically different for laser in situ keratomileusis and laser-assisted subepithelial keratectomy treatments. Univariate multilinear analyses showed that the spherical equivalent (SE) was correlated with the attempted SE and stromal refractive index (or hydration). Analyses suggest overcorrections for higher stromal refractive index values and for lower hydration values. CONCLUSIONS: The stromal refractive index and hydration affected postoperative outcomes in a subtle, yet significant manner. An adjustment toward greater attempted correction in highly hydrated corneas and less intended correction in low hydrated corneas might help optimize refractive outcomes. FINANCIAL DISCLOSURE: Mr. Magnago and Dr. Arba-Mosquera are employees of and Dr. Diego de Ortueta is a consultant to Schwind eye-tech-solutions GmbH & Co. KG. Mr. Rüden has no financial or proprietary interest in any material or method mentioned.

In vivo measurements of thermal load during ablation in high-speed laser corneal refractive surgery.

PURPOSE: To evaluate the thermal load of ablation in high-speed laser corneal refractive surgery with the AMARIS excimer laser (SCHWIND eye-tech-solutions). METHODS: Thermal load from refractive corrections on human corneas using a 500-Hz laser system with a fluence of 500 mJ/cm(2) and aspheric ablation profiles was recorded with an infrared thermography camera. Each single in vivo measurement was analyzed and temperature values were evaluated. RESULTS: Overall, the maximum temperature change of the ocular surface induced by the refractive ablations was ≤4°C. The increase in the peak temperature of the ocular surface never exceeded 35°C in any case. This low thermal load was independent of the amount of correction the eye achieved. CONCLUSIONS: The thermal load of the ablation in high-speed laser corneal refractive surgery was minimized using a computer algorithm to control the peak temperature to avoid corneal collagen denaturation with minimal compromise on treatment duration.

Bioptics in sutureless intrascleral multifocal posterior chamber intraocular lens fixation.

PURPOSE: To present a technique for sutureless fixation of a three-piece, multifocal, posterior chamber intraocular lens (IOL) in the ciliary sulcus. METHODS: A 24-year-old woman presented with bilateral subluxation of the crystalline lens. Two straight sclerotomies were prepared with a 24-gauge cannula 2.0 mm from the limbus 180° apart from each other. The cannula was used to create a 2.0- to 3.0-mm tunnel parallel to the limbus starting from the sclerotomies. The leading haptic of the multifocal IOL was grasped at its tip with end-gripping, 25-gauge forceps and pulled through the sclerotomy. The forceps was used to introduce the IOL haptic into the scleral tunnel parallel to the limbus. RESULTS: Multifocal posterior chamber IOLs were stable and well centered. No postoperative complications occurred in the 16-month follow-up period. Preoperative astigmatism was corrected after IOL implantation with corneal wavefront-guided laser epithelial keratomileusis. CONCLUSIONS: Sutureless fixation of multifocal posterior chamber IOL haptics in a scleral tunnel parallel to the limbus can be successful, resulting in long-term centration and three-dimensional axial stability for optimal refractive results. If necessary, postoperative wavefront-guided refractive correction can be performed to optimize final refraction.

Correlation among ocular spherical aberration, corneal spherical aberration, and corneal asphericity before and after LASIK for myopic astigmatism with the SCHWIND AMARIS platform.

PURPOSE: To determine the spherical wave aberration of the human eye based on corneal topography. METHODS: Based on the pre- and postoperative status of 146 consecutive eyes (median patient age 36 years), the correlations between spherical aberration and asphericity and between corneal and ocular spherical aberrations were determined using simple linear regression methods. The asphericity (Q) values for which spherical aberration equals zero as well as the reference Q values for which corneal spherical aberration equals ocular spherical aberration have been determined. Patients underwent LASIK using the AMARIS excimer laser platform (SCHWIND eye-tech-solutions). All ablations were based on aspheric aberration-neutral profiles. RESULTS: Corneal and ocular spherical aberrations correlate well with Q value and the value p · R(-3) in patients before and after LASIK for myopic astigmatism. A Q value of -0.19 to -0.27 can provide zero ocular spherical aberration in patients before and after LASIK for myopic astigmatism. Ocular spherical aberration is induced at a rate of half the induced corneal spherical aberration. A reference Q value of -0.12 to +0.01 can provide corneal spherical aberration equal to ocular spherical aberration in patients before and after LASIK for myopic astigmatism. CONCLUSIONS: Ocular and corneal wave aberrations are two different concepts that are not interchangeable. As for spherical aberration, a simple static model with a reference cornea deviating from a Cartesian oval can provide a 2:1 correspondence between corneal and ocular spherical aberration.