Correction of refractive errors by subtractive corneal surgery: History and perspectives

To investigate the optimal intraocular lens (IOL) corrections for virtual eyes with moderate to severe keratoconus (KC) using ray tracing and comparative analysis of image quality. Computer simulations conducted using MATLAB-based custom ray-tracing software. The study included 20 eyes generated from a statistical eye model called SyntEyes, which produces eye biometrics for KC eyes for optical simulation. The visual Strehl ratio (VSX) was used to quantify image quality based on optical wavefront analysis. The eyes underwent various simulated corrections, including spherical and toric IOLs, as well as spherical and toric rigid gas-permeable (RGP) contact lenses, both individually and in combination. Comparisons were made across different correction strategies. Spherical and toric IOLs alone modestly improved VSX to 0.025 ± 0.004 and 0.034 ± 0.005, respectively, from a baseline of 0.013 ± 0.003 (P < .001). By contrast, eyes corrected with toric RGP lenses after IOL implantation demonstrated significantly higher image quality: 0.250 ± 0.014 (spherical IOL) and 0.246 ± 0.014 (toric IOL) (P < .001). However, combining 2 toric elements often led to overcorrection and increased aberrations. IOL corrections alone are insufficient to compensate for large corneal aberrations present in KC eyes. Subsequent fitting with toric RGP lenses can restore most eyes to normal levels of visual image quality. Among the compared IOL corrections, the combination of a spherical IOL with a toric IOL gave the best average VSX on average and avoids chances of overcorrection.

To evaluate the visual, refractive, and aberrometric outcomes of a toric (T) FIL-SSF intraocular lens (IOL) implanted in aphakic eyes lacking capsular support. Ospedale Piero Palagi and Azienda Ospedaliera Universitaria Careggi, Florence, Italy. Multicenter prospective observational case series. Aphakic eyes with regular corneal astigmatism >1 D underwent sutureless transscleral fixation of a T FIL-SSF IOL. Preoperative assessment included UDVA, CDVA, manifest refraction, corneal tomography, and biometry. Postoperative visits occurred at 1 day, 7 days, and 1, 3, and 6 months. At 6 months, vector astigmatism analysis, wavefront aberrometry, and IOL alignment were performed. Fifteen eyes from 12 patients completed the 6-month follow-up. Mean UDVA improved from 0.96 ± 0.25 to 0.19 ± 0.10 logMAR and CDVA from 0.41 ± 0.32 to 0.04 ± 0.05 logMAR (both P < .001). Mean postoperative spherical equivalent prediction error was -0.12 ± 0.54 D. Mean absolute corneal astigmatism decreased from 2.15 ± 0.54 D to a mean refractive astigmatism of 0.73 ± 0.48 D. Wavefront aberrometry showed total astigmatism of 0.36 ± 0.28 µm, with mean total higher order aberrations (HOAs) of 0.24 ± 0.08 µm. Mean IOL misalignment was 3.33 ± 3.42°, significantly correlated with residual refractive astigmatism (ρ = 0.71 P < .01). T FIL-SSF IOL implantation provided substantial improvements in visual acuity, predictable refractive outcomes, and significant cylinder reduction in aphakic eyes with corneal astigmatism lacking capsular support.

Solar Ground-Layer Adaptive Optics (GLAO) is the preferred solution for achieving wide-field, high-resolution imaging in ground-based solar telescopes. However, current GLAO guide-star (GS) arrangement optimization relies on extensive iterative simulations, which are time-consuming and resource-intensive, and do not provide a prior reference for system design. To address this issue, an analysis of GLAO wavefront sensing in the spatial frequency is conducted. A filter is constructed to optimize the detection of conformal aberrations, leading to the development of an analytical framework for GS arrangement optimization. This framework provides accurate prior optimization results for any GS configuration. The correctness of the theory is validated through comparison with Monte Carlo simulations, and the practical utility of this method in optimizing solar GLAO system performance is demonstrated.

We aimed to compare the anterior corneal aberrometry between Pentacam HR, a Scheimpflug-based imaging system, and Peramis, an aberrometer that combines a pyramidal wavefront sensor with Placido-disk topography. Myopic, otherwise healthy patients who were scheduled for refractive surgery were examined for anterior corneal aberration profiles using Pentacam HR and Peramis in a 4 mm pupil-centered analysis zone. This profile included corneal total aberrations (TAs), lower-order aberrations (LOAs), higher-order aberrations (HOAs), trefoil (Z(3,-3), Z(3,3)), coma (Z(3,-1), Z(3,1)), and spherical aberrations (Z(4,0)). Subgroup analysis was performed according to the laterality of eyes and the severity of myopia. In addition to the root mean square micrometer (RMS µm), the aberrometry data were simultaneously presented as equivalent diopters to facilitate clinical understanding. A difference of less than 0.5 diopter or 0.3 RMS µm was considered clinically interchangeable. A total of 160 eyes from 80 patients were included. Pentacam HR consistently showed significantly higher corneal TAs, LOAs, HOAs, and SA in both eyes (p < 0.01). There was a moderate correlation for corneal TAs, LOAs, and coma aberrations (ICC: 0.39-0.59). In contrast, the correlation was poor for trefoil and spherical aberrations (ICC: 0.16-0.38) and almost non-existent for HOAs (ICC: 0.01-0.07). The width of the 95 % limits of agreement was too large across all comparisons, exceeding 2 RMS µm for TAs and LOAs and 1 RMS µm for HOAs. It was also approximately 0.5 RMS µm for trefoil, coma, and spherical aberrations. Similar patterns were observed in subgroups, regardless of eye laterality or myopia severity. Despite moderate correlations in some Zernike terms, the two systems could not be used interchangeably. This is important in pre-operative planning, where patients with higher HOAs might be/not be candidates for particular cataract or wavefront-based refractive surgeries.

This study investigated the relationship between watercleft localization in crystalline lenses and higher-order aberrations. Single-center, retrospective, observational study METHODS: The study included 131 right eyes from 131 patients. The patients underwent complete ophthalmic examinations, swept-source anterior-segment optical coherence tomography (Tomey Corporation), and wavefront analysis with a wavefront analyzer (Topcon Corporation). Waterclefts were classified according to the Kanazawa Medical University Cataract Classification and Grading System. On the basis of their location, the central and peripheral watercleft types were further categorized as anterior waterclefts (AWC) or posterior cortical waterclefts (PWC). The total cross-sectional areas and volumes of the central waterclefts were 7.722 ± 5.926 mm2 and 1.413 ± 1.357 mm3 for the C-AWC and 2.443 ± 2.422 mm2 and 0.214 ± 0.286 mm3 for the C-PWC, respectively. The size (area and volume) of the C-AWC was significantly larger than that of the C-PWC. Both eyes exhibited significantly higher levels of higher-order aberrations and lower visual acuity than did the clear eye in both cases (P <.05). Central-type waterclefts caused visual deterioration, with a significant correlation between size and visual function. For the same cross-sectional area and volume, the effects on higher-order aberrations and visual acuity were greater with C-PWC than with C-AWC.

AIM:The aim of the study was to study and compare the higher-order aberrations (HOAs) in myopes and emmetropes.SUBJECTS AND METHODS:This study was done as a cross-sectional, comparative study consisting of 288 myopic eyes and 322 emmetropic eyes yes. All patients included in the study underwent a complete eye examination, including refraction, slit lamp examination, and wave front analysis using Baush and Lomb Zywave aberrometer. The wavefront maps were analyzed using a 6 mm pupil diameter and up to the fifth order of Zernike coefficients.RESULTS:The mean age in the myopic group was 24.5 ± 4.5 years. The mean spherical equivalent in the myopic group was − 3.5 ± 2.7 D. A statistically significant (P ≤ 0.05) negative correlation (r = −0.2) was noted between the spherical equivalent and total higher order root mean square (HO RMS) (from 3rd to 5th) in the myopia group. The mean age in the emmetropic group was 25.04 ± 6.39 years. A statistically significant (P ≤ 0.05) positive correlation was noted between age and total HO RMS in the emmetropia group. Comparison of HOAs between the myopia group and emmetropia group revealed a statistically significant difference (P ≤ 0.05) in the mean value of vertical coma, fourth-order spherical aberration. The mean value of total HO RMS (third to fifth order aberrations) in the myopia and emmetropia groups was found to be 0.444 ± 0.167, 0.412 ± 0.156 μm, respectively.CONCLUSION:We found more total levels of HOAs in myopic eyes compared to emmetropes.

To evaluate refractive outcomes, defocus curve, wavefront analysis, and automated refraction of a novel monofocal intraocular lens (IOL) with higher order aspheric coefficients and controlled curvature change. This prospective observational study included 29 eyes of 29 consecutive patients with healthy eyes and normal visual potential who had undergone cataract surgery and implantation of the enVista Aspire IOL (Bausch + Lomb, Inc). Outcome measures included monocular uncorrected (UDVA), corrected (CDVA), distance-corrected intermediate (DCIVA) (at 66 cm), and distance-corrected near (DCNVA) (at 40 cm) visual acuity, defocus curve, wavefront analysis, mean refractive prediction error, and automated and manifest (MRSE) refraction spherical equivalent. Mean UDVA was 20/22, with 93.1% of eyes having 20/25 or better. Mean CDVA was 20/20, with all eyes having 20/25 or better. Mean DCIVA was 20/34, with 90% of eyes having 20/40 or better. Mean DCNVA was 20/38, with 83% of eyes having 20/40 or better. The monocular defocus curve demonstrated approximately 1.50 diopters (D) depth of focus for visual acuity of 0.2 logarithm of the minimum angle of resolution or better. Postoperative mean MRSE was close to emmetropia (0.02 ± 0.29 D), and 96.6% of eyes were within ±0.50 D. Automated refraction measured with ray-tracing, dynamic sciascopy, and Hartmann-Shack devices were within ±0.25 D of the subjective refraction. The postoperative ocular 4th-order spherical aberration measured with Hartmann-Shack aberrometer was 0.08 and 0.15 µm for a 4.5- and 6-mm pupil, respectively. Implantation of a new enhanced monofocal IOL demonstrated useful near and intermediate vision while maintaining excellent distance acuity. Wavefront analysis revealed minimal postoperative spherical aberration, and the automated refraction was near emmetropia.

Abstract The application of focus-tunable lenses (FTL) has significantly expanded in the field of photonics in the last decade, establishing these devices as fundamental optoelectronic components in most experimental setups. An electrically-addressed FTL allows fine, continuous, and dynamic power adjustment within a range of diopters. In many applications, the FTL is oriented horizontally, with vertical optical axis. However, those applications requiring alternative orientations are prone to be affected by aberrations due to the gravitational force effects on the optical fluid and elastic membrane of this device. A new FTL introduces a compensation for gravity, aiming to compensate for the induced coma. This study focuses on the optical performance of a gravity-compensated FTL, Optotune EL-16-40-GTC-VIS-5D (Optotune Switzerland AG). A comprehensive experimental wavefront characterization was conducted across the addressable power range (5 D) by measuring and analyzing the induced primary astigmatism, coma and spherical aberrations in a 6 mm-diameter aperture, with 530 nm illumination, with the lens in both horizontal (i.e., parallel to laboratory ground) and vertical (upright) lens orientations. A detailed comparison with two uncompensated standard models of the same brand (Optotune EL-16-40-TC-VIS-5D and EL-16-40-TC-VIS-5D-E) is presented in terms of measured wavefront error. The results showed the gravity-compensated FTL effectively corrected induced vertical coma when used upright. In contrast, the astigmatism induced (0.06 μm in both horizontal and vertical orientations) exceeded the observed vertical coma (around 0.030 μm) of the upright standard models. Additionally, such astigmatism (0.06 μm) is approximately three times greater than the astigmatism induced by the standard models in both positions. These results provide a valuable insight about induced aberrations, which can be particularly relevant for vision testing experiments and adaptive optics applications, both requiring precise aberration control. The astigmatism introduced by gravity-compensated FTLs, as well as other induced aberrations, can be significant, potentially masking the effects of other optical components or acting as confounding factors.

PurposeTo assess the objective depth-of-focus after implantation of isofocal intraocular lens (IOL) during cataract surgery based on VSOTF using ray tracing aberrometry.MethodsIn this prospective study, 40 eyes were implanted with the isofocal Isopure IOL (Beaver-Visitec International, Inc. [BVI], Waltham, USA). The patient assessments considered: refraction (sphere, cylinder and axis), uncorrected-distance visual acuity (UDVA), corrected-distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA, at 60 and 80 cm), distance-corrected and uncorrected near visual acuity (DCNVA and UNVA), wavefront aberrations and objective depth-of-focus using ray-tracing optical technology from several percentages of degradation on the visual Strehl ratio based on the optical transfer function (VSOTF, 90%, 80% and 60%). Patients were assessed at 3 months post-surgery.ResultsEyes implanted with the isofocal IOL showed good outcomes in terms of refraction and visual acuity at the last follow-up visit. Specifically, half a dioptre was obtained for the spherical equivalent and about 20/20 for CDVA, about 20/25 for UIVA at 80 cm, about 20/30 for UIVA at 60 cm, and about 20/25 for DCNVA. In relation to the objective depth-of-focus computed from the wavefront analysis in our cohort, we obtained mean values of 2.12 D, 3.16 D and 4.94 D at 90%, 80% and 60% of degradation, respectively.ConclusionOur study shows that the isofocal IOL provides high values of objective depth-of-focus based on the VSOTF using ray tracing optical technology when implanted after cataract surgery.

This study presents a single-frame multi-fringe decomposition algorithm for dual-lateral shearing interferometry, which effectively suppresses mode aliasing and reduces interferogram noise. The proposed technique advances interferometric analysis through its unique ability to directly decompose superimposed fringe patterns while preserving phase integrity. Through comprehensive numerical simulations, the algorithm demonstrates superior performance compared to conventional methods, particularly in reducing wavefront reconstruction errors. Experimental validation using a deformable mirror monitoring system confirms both the high precision and practical advantages of our method, demonstrating wavefront reconstruction accuracy below 0.3 µm in peak-to-valley (PV) error and 0.07 µm in root-mean-square (RMS) error, representing 55% and 52% improvements, respectively, over conventional approaches. The demonstrated computational efficiency and robustness of this technique highlight its significant potential for real-time measurement applications in advanced optical metrology systems, offering improved precision in real-time wavefront analysis compared to existing approaches.

PurposeTo assess the ability of corneal epithelial aberrations to discriminate forme fruste keratoconus (FFKC) and keratoconus (KC) from normal eyes.MethodsThis prospective, case-control study enrolled 91 right eyes from 91 normal participants, 87 eyes with FFKC and 148 eyes with KC. Epithelial aberrations for the 6-mm pupil were measured using an anterior segment optical coherence tomography (MS-39, CSO). The epithelial root mean square of higher and lower-order aberrations (total RMS), root mean square of higher-order aberrations (HOAs RMS, from the 3rd to the 7th Zernike polynomials), coma, trefoil, spherical aberration, and secondary astigmatism were recorded. Stepwise logistic regression was utilized to develop the epithelial aberrations index (EAI) for obtaining the optimal discriminant function to diagnose FFKC (EAI-FFKC) and KC (EAI-KC). Area under the receiver operating characteristic curve (AUC) analysis was used to determine the diagnostic accuracy of the indices.ResultsFFKC and KC eyes had significantly higher epithelial aberrations than normal eyes. Comparing FFKC with the normal group, epithelial HOAs RMS and coma attained AUC values of 0.714 and 0.788, respectively. The EAI-FFKC showed the highest discrimination ability to differentiate FFKC from normal eyes indicated by an AUC value of 0.822 with 77.0% sensitivity and 75.8% specificity. Comparing KC with the normal group, epithelial HOAs RMS attained AUC values of 0.976–0.998 with 95.2%–100% sensitivity and 92.3%–96.7% specificity, epithelial coma attained AUC values of 0.974–0.997 with 92.9%–100% sensitivity and 96.7%–98.9% specificity. The EAI-KC showed the highest discriminative ability to differentiate KC from normal eyes indicated by AUC of 0.996 with 98.6% sensitivity and 98.9% specificity.ConclusionEpithelial wavefront analysis can identify abnormal epithelial changes across all stages of KC, from very early to severe. Epithelial aberrations can be used as a diagnostic tool for KC and FFKC.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40662-025-00449-x.

PurposeTo evaluate ocular aberrations, visual and refractive outcomes in eyes implanted with a monofocal intraocular lens (IOL) with a positive asphericity profile.Patients and MethodsThis prospective observational study included 42 eyes (27 patients) that underwent routine cataract surgery and implantation of RayOne EMV monofocal aspheric IOL. PentacamWave was used to assess corneal (at 4.5 and 6.0-mm diameter) and total ocular wavefront aberrations (at 3.0, 3.5, 4.0, and 4.5-mm pupil). Postoperative assessments between 1 and 3 months included manifest and automated refraction, uncorrected and corrected distance visual acuity (UDVA, CDVA), and distance-corrected intermediate and near visual acuity (DCIVA, DCNVA).ResultsPostoperatively, UDVA was 0.06 logMAR, with 100% eyes achieving CDVA of 20/25 or better. DCIVA was 0.19 logMAR, with 66.7% of the eyes achieving 20/30 or better. DCNVA was 0.24 logMAR, with 54.8% of the eyes 20/30 or better. Automated refraction measured with various devices revealed myopic results compared to manifest refraction (−0.24 ± 0.32 D). The mean corneal spherical aberration (4th order) for a 4.5-mm pupil was 0.08 ± 0.06 µm. Total ocular wavefront aberrometry (RMS) showed 0.14 ± 0.04 µm of 4th-order spherical aberration (SA), −0.03 ± 0.10 µm of 6th-order SA, and 0.12 ± 0.06 µm of coma for a 4.5 mm pupil.ConclusionIn vivo wavefront analysis of eyes implanted with this enhanced monofocal IOL suggests that the IOL’s positive asphericity profile incremented the pre-existing corneal aberrations, leading to useful intermediate and near vision while maintaining distance-corrected visual acuity better than 20/25 in all eyes.

Purpose: To evaluate whether corneal topography map stitching can fully substitute the traditional single-shot capture methods in clinical settings. Methods: This record review study involved the measurement of corneal surfaces from 38 healthy subjects using two instruments: the Medmont Meridia, which employs a stitching composite topography method, and the Eye Surface Profiler (ESP), a single-shot measurement device. Data were processed separately for right and left eyes, with multiple gaze directions captured by the Medmont device. Surface registration and geometric transformation estimation, including neighbouring cubic interpolation, were applied to assess the accuracy of stitched maps compared to single-shot measurements. Results: The study evaluated eye rotation angles and surface alignment between Medmont topography across various gaze directions and ESP scans. Close eye rotations were found in the right-gaze, left-gaze and up-gaze directions, with rotation angles of around 8°; however, the down-gaze angle was around 15°, almost twice other gaze rotation angles. Root mean squared error (RMSE) analysis revealed notable discrepancies, particularly in the right-, left-, and up-gaze directions, with errors reaching up to 98 µm compared to ESP scans. Additionally, significance analyses showed that surface area ratios highlighted considerable differences, especially in the up-gaze direction, where discrepancies reached 70% for both right and left eyes. Conclusions: Despite potential benefits, the findings highlight a significant mismatch between stitched and single-shot measured surfaces due to digital processing artefacts. Findings suggest that stitching techniques, in their current form, are not yet ready to substitute single-shot topography measurements fully. Although stitching helps fit large-diameter contact lenses, care should be taken regarding the central area, especially if utilising the stitched data for optimising optics or wavefront analysis.

To use a portable electromyographic (EMG) system for the objective evaluation of glare-induced discomfort in patients with keratoconus. Fifty-five eyes of 31 patients and 24 controls were enrolled in this retrospective case-control study. The electrical activity of the mimic muscles was recorded at three different luminances (500, 3000, and 6000 lux) using a portable EMGsystem. A discomfort glare value was obtained as the signal/noise ratio for each recording.All the patients were asked to grade their discomfort after exposure to each luminance using the subjective de Boer scale. Corneal topography-based wavefront analysis, pupil size, and angle kappa were calculated to identify possible significant correlations. Mean values of discomfort glare index (signal/noise ratio) for the patients' group were 1.66 ± 1.5 at 500 lux, 2.71 ± 1.68 at 3000 lux, and 3.16 ± 1.92 at 6000 lux; for the control group, 1.4 ± 0.4 at 500 lux, 1.9 ± 0.86 at 3000 lux, and 2.13 ± 0.9 at 6000 lux. There was a statistically significant difference at the level of 0.05 between the two groups only at the 6000-lux illuminance level. There was a significant Spearman's correlation at all luminances between the objective electromyographic recording and the subjective grading of the discomfort feeling. There were no statistically significant correlations between electromyographic responses and keratometric values, pupil size, or angle kappa. Trefoil and coma were significantly correlated with discomfort glare-estimated electromyographic values. Patients with keratoconus experience higher levels of discomfort when exposed to a glare source, as measured objectively with electromyographic recordings, which may affect their quality of vision.

Abstract We investigate traveling wave solutions for a nonlinear system of two coupled reaction-diffusion equations characterized by double degenerate diffusivity: n t = − f ( n , b ) , b t = [ g ( n ) h ( b ) b x ] x + f ( n , b ) . These systems mainly appear in modeling spatio-temporal patterns during bacterial growth. Central to our study is the diffusion term g ( n ) h ( b ) , which degenerates at n = 0 and b = 0; and the reaction term f ( n , b ) , which is positive, except for n = 0 or b = 0. Specifically, the existence of traveling wave solutions composed by a couple of strictly monotone functions for every wave speed in a closed half-line is proved, and some threshold speed estimates are given. Moreover, the regularity of the traveling wave solutions is discussed in connection with the wave speed.

Vortex beams carrying orbital angular momentum (OAM) provide an infinite degree-of-freedom and hold high potential in various applications, from high-capacity optical communication to diagnosis of materials with chirality. Quantitative spatial spectrum analysis of OAM modes is essential for these applications, yet it is still a challenge to obtain the OAM spectrum under short-wavelength systems such as extreme ultraviolet (EUV) and x-ray. Here, we introduce a simple single-shot diffractive method that can reconstruct arbitrary helical wavefront and quantitatively decompose individual OAM modes. There is no need to conduct any calibration associated with the beam to be measured; the only prior knowledge required is the transmission function of a random diffusing wavefront modulator. Experimental results show that this method can retrieve the spectrum of arbitrary OAM modes with intermodal crosstalk lower than −16.91 dB for topological charge greater than 50. The proof-of-concept visible light experiments of multiplexing and demultiplexing of OAM modes showed its potential applications in laser communication and metrology. Given the simplicity of lens-less system setup, the single-shot capability, and its suitability for arbitrary OAM modes, we envision it setting up a brand-new diffractive solution for structured wavefront analysis over a broad spectral range, from visible light to EUV, x-ray, and even electron beam.

To compare the aberrometric profile of the Artisan Aphakia lens (Opthec BV) and transscleral plug FIL-SSF lens (Soleko) and to assess the impact of tilt and decentration on their optical performance. This retrospective observational study was conducted at Azienda Ospedaliera Universitaria Careggi, Florence, Italy, with a consecutive cohort of aphakic eyes undergoing secondary lens implantation with an Artisan or FIL-SSF lens. Wavefront analysis was performed using a pyramidal wavefront-based aberrometer (Osiris-T; CSO). Tilt and decentration were calculated using anterior segment optical coherence tomography (MS-39; CSO). The study included 47 eyes from 45 patients: 24 eyes in the FIL-SSF group and 23 eyes in the Artisan group. Decentration was 0.39 ± 0.14 mm in the FIL-SSF group and 0.51 ± 0.16 mm in the Artisan group (P = .02). The mean tilt value was 6.6 ± 2.35 degrees in the FIL-SSF group and 5.9 ± 1.86 degrees in the Artisan group (P = .13). Internal higher order aberrations (HOAs) were 0.23 ± 0.07 μm in the FIL-SSF group and 0.29 ± 0.13 μm in the Artisan group (P = .02). The point spread function (PSF) Strehl ratio was 0.12 ± 0.05 in the FIL-SSF group and 0.10 ± 0.04 (P = .11) in the Artisan group. The PSF Strehl ratio without lower order aberration (PSFw2) was 0.28 ± 0.12 in the FIL-SSF group and 0.23 ± 0.09 in the Artisan group (P = .01). The Artisan and FIL-SSF lenses provide comparable optical performance in terms of the PSF Strehl ratio. However, the Artisan lens appears to be more susceptible to decentration, which may result in increased higher order aberrations and a consequently lower PSFw2 Strehl ratio. [J Refract Surg. 2024;40(12):e926-e933.].

Abstract The technique of 3D-printed micro-optics has experienced significant advancements over the last few years [1, 2]. This progressive evolution has been marked by remarkable strides in precision and miniaturization, making it particularly attractive to applications in the field of medical endoscopy. One noteworthy application entails the fabrication of micro-lenses directly on optical fibers, thereby creating endoscopic devices with unparalleled capabilities. A significant attribute of these micro-optical systems lies in their capability for precise imaging and their adept navigation through exceptionally narrow biological structures. For instance, the application of the 3D-printed endoscopy technology has facilitated insertion into the aorta of mice, as well as severely diseased human carotid arteries [2, 3]. This unprecedented level of accessibility and adaptability holds immense promise for diagnostic and therapeutic interventions in the realm of cardiovascular medicine and beyond. In the future, it may also be conceivable for micro-lenses to serve not only as imaging tools, but also as integral components of 3D-printing processes aimed at repairing damaged human tissue with bio-materials. For micro-lens production and quality control, performance assessment is invariably necessary to assure diffraction limited imaging in the different optical applications. With confocal surface profiling, only the surface shape information of micro-optics can be obtained. However, not only the shape of 3D-printed optics is relevant for its quality, but also its refractive index distribution is crucial when determining its overall optical performance. Therefore, the measurement of the wavefront is decisive in evaluating lens performance. Lateral shear interferometry presents itself as a compact and precise method for wavefront measurements. The only essential component required in the set-up is a pair of glass plates with high surface quality. Consequently, the entire set-up can be notably streamlined, as there is no requirement to construct an interferometer reference arm. This advantage facilitates the development of a notably compact set-up, making lateral shear interferometry particularly advantageous for integration with microscope and 3D-printer, despite the requirement for more complex algorithms in analyzing lateral shear interferograms. In this paper, simulation of shear interferogram fringes corresponding to wavefronts exhibiting varying aberrations are discussed. Additionally, this research encompasses measurement and analysis of shear interferograms obtained from wave fronts transmitted through different lenses. Through meticulous examination of these experimental results, the characteristics and performance of the tested optical systems are elucidated, contributing to a deeper understanding of wavefront analysis methodologies and their applicability in optical characterization studies.

Synopsis: Corneal epithelial wavefront error and epithelial thickness variance qualify as highly sensitive and specific biomarkers for epithelial basement membrane dystrophy (EBMD). The biomarkers show a normalization after treatment of EBMD with phototherapeutic keratectomy. Purpose: To gauge the diagnostic value of epithelial basement membrane dystrophy (EBMD), a novel spectral-domain optical coherence tomography (SD-OCT)-based imaging modality for simultaneous morphological (thickness profile) and refractive (optical wavefront) assessment of the corneal epithelial layer in one of the most common but often underdiagnosed corneal dystrophies. Methods: In this prospective observational study, a total of 32 eyes of 32 patients diagnosed with EBMD and 32 eyes of 32 healthy control subjects were examined with high-resolution anterior segment SD-OCT (MS-39; CSO, Florence, Italy). Various epithelial thickness and epithelial wavefront-derived terms were compared between groups and receiver operating characteristic (ROC) curves were computed to analyze the diagnostic capacity of the respective parameters. A total of 17 of 32 EBMD patients underwent treatment with phototherapeutic keratectomy (PTK) and were followed up for 3 months. Results: Epithelial thickness variance (60.4 ± 56.7 µm versus 7.6 ± 6.1 µm) and interquartile range (11.0 ± 6.9 versus 3.3 ± 1.9 µm) were markedly elevated in EBMD patients as compared with healthy controls (both with p < 0.001). Epithelial wavefront analysis showed a highly statistically significant excess in all examined aberration terms in EBMD patients (all with p < 0.001). Significantly greater areas under the curve (AUCs) were yielded by the epithelial wavefront-derived parameters (e.g., total epithelial wavefront error: AUC = 0.966; 95% confidence interval (CI) 0.932-1) than by the epithelial thickness-derived parameters (e.g., variance: AUC = 0.919; 95% CI 0.848-0.990). Conclusions: Corneal epithelial wavefront aberrometry proved valuable as an objective biomarker for EBMD, with high sensitivity and specificity. PTK resulted in a reduction of morphological and refractive epithelial irregularities in EBMD.