PURPOSE:To report the first case of stromal lenticule addition keratoplasty performed for the management of severe progressive corneal flattening following corneal cross-linking (CXL). METHODS:A 63-year-old woman with keratoconus, previously treated with combined topography-guided photorefractive keratectomy and CXL (Athens protocol), presented with progressive corneal flattening and a hyperopic shift in the left eye. Corrected distance visual acuity (CDVA) was 20/50 with manifest refraction of +5.00 -1.50 × 123° and the mean keratometry was 36.20 diopters (D). Stromal lenticule addition keratoplasty was performed using a stromal lenticule obtained from a myopic small incision lenticule extraction treatment. A femtosecond laser was used to create an intrastromal pocket, and the lenticule was inserted and centered within the stromal interface. RESULTS:Postoperatively, mean keratometry increased to 41.20 D and refraction improved to +0.50 -2.00 × 110°, with 20/40 CDVA. Corneal curvature remained stable at 12 months postoperatively. CONCLUSIONS:Stromal lenticule addition keratoplasty may represent a safe and effective minimally invasive surgical option for inhibiting the progressive corneal flattening, restoring corneal curvature and correcting the excessive hyperopia in cases of severe corneal flattening following CXL.
PURPOSE:To determine whether objective biometry can guide intraocular lens formula selection in post-laser vision correction (LVC) eyes with indeterminate classification of actual LVC type (total keratometry [TK] TKave - keratometry [K] Kave = 0.00 to 0.06), and to compare refractive accuracy among contemporary LVC formula strategies. METHODS:A total of 507 post-LVC eyes (inclusive of both myopic [M-LVC] and hyperopic [H-LVC] eyes) with TKave - Kave between 0.00 and 0.06 measured by swept-source optical coherence tomography biometry (IOLMaster 700; Carl Zeiss Meditec AG) were analyzed. Refractive prediction errors were calculated for 22 formulas, including eight H-LVC, eight M-LVC, and six non-LVC formulas. Formula performance was assessed using root mean square error rankings and heteroscedasticity testing for dependent data. The main outcome measure was refractive prediction error and proportion of eyes within ±0.50 diopters (D) of target refraction. RESULTS:H-LVC formulas demonstrated superior refractive accuracy across all eyes, regardless of reported LVC type. Pearl DGS and Barrett True K No-History (H-LVC) achieved the highest proportion of eyes (approximately two-thirds) within ±0.50 D of target. K-based H-LVC formulas outperformed variants incorporating posterior K or TK. Standard formulas showed intermediate performance, whereas M-LVC formulas ranked lowest. Differences between top-performing formulas were statistically significant. CONCLUSIONS:In post-LVC eyes with TKave - Kave between 0.00 and 0.06, H-LVC formulas provide the most accurate refractive outcomes, independent of reported treatment type. These findings challenge reliance on historical LVC classification for formula selection and support a measurement-driven approach in which biometry-guided formula selection improves outcomes when history is unreliable in ambiguous post-LVC eyes.
Purpose: To evaluate visual and refractive outcomes across different cyclorotation magnitudes in myopic laser in situ keratomileusis (LASIK) using automated cyclorotation compensation. Methods: This retrospective comparative study included consecutive patients who underwent myopic LASIK between 2012 and 2023. Patients were divided into three groups according to their cyclorotation angle magnitude. A comparison of baseline and intraoperative parameters was performed. Refractive and visual outcomes were assessed, including efficacy and safety indices, and an Alpins vector analysis was performed. Multiple linear regression was used to identify the effect of potential confounders. Results: Overall, 6,920 eyes of 4,454 patients were included. The mean age was 30.7 ± 8.7 years and 47.7% (2,130) were women. Analysis indicated significant differences in corrected distance visual acuity between the groups, but post-hoc analysis revealed no significant pairwise differences. Other visual and refractive outcomes including the calculated indices showed no significant differences. Alpins vector analysis showed no significant differences between the groups in any of the vectors in either magnitude or direction, nor were there significant differences in the calculated indicators. Multiple linear regression suggested age, maximum ablation depth, rotation direction, preoperative axis, and treated axis had confounding effects mostly on Alpins vectors. However, no significant effect was noted for outcomes that showed significant differences. Conclusions: Cyclorotational angle magnitude did not significantly impact visual or refractive outcomes in myopic LASIK when using modern laser devices. These findings suggest limited clinical relevance of cyclorotation degrees in LASIK outcomes, with other factors potentially playing a more significant role in surgical planning.
Purpose: To evaluate wavefront aberrations in eyes implanted with rotationally asymmetric refractive bifocal intraocular lenses (IOLs) using a modified Shack-Hartmann wavefront sensor (SHWS) designed to mitigate artifactual coma. Methods: In this simulation study, postoperative optical quality was evaluated using wavefront analysis in the presence of various ocular aberrations. A bifocal phase map (3.00 diopter [D] near addition, 50% energy distribution) was introduced in a computer eye model (5-mm pupil; 850-nm light source). The emerging wavefront displaced the simulated SHWS lenslet images from their reference positions. Wavefronts were evaluated using: (1) the standard integration method, considering lenslet images across the entire circular pupil, and (2) the proposed method, which captures SHWS data at near and far foci and combines in-focus lenslet images from the corresponding zones of the bifocal IOL. The interaction between the pupillary phase and induced wavefront aberrations (0.25 µm amplitude) was further analyzed using both methods. Results: In the absence of ocular aberrations, standard integration detects a substantial artifactual primary vertical coma with a wavefront root mean square (RMS) of 0.57 µm. In contrast, the proposed method reduced the residual RMS to 0.01 µm. In the presence of aberrations up to the fourth order, the proposed method achieved a mean residual RMS of 35 nm, enabling diffraction-limited wavefront sensing. Conclusions: The proposed SHWS integration method overcomes the phase asymmetry of segmented bifocal IOLs. By providing precise postoperative wavefronts and through-focus visual quality metrics, this approach offers a robust tool for clinical evaluation of patients implanted with these IOLs.
Purpose: To evaluate cone stromal ablation depth with varying optical zones using different customized ablation strategies in keratoconus. Methods: This retrospective computational analysis assessed 59 eyes from 59 patients with mild to moderate keratoconus using three different simulation approaches. The first approach involved treating the full manifest refraction along with the corneal higher order aberrations (HOAs). The second approach, following the Athens Protocol, targeted all HOAs with up to 70% correction of the cylinder and sphere, limiting cone stromal ablation to 50 µm at an optical zone (OZ) of 5.5 mm. The third approach treated all HOAs and included only the sphere and cylinder embedded within the HOA ablation profile, as calculated by the ORK CAM software for the SCHWIND AMARIS (SCHWIND eye-tech-solutions GmbH). All models were simulated on the ORK module, with OZ ranging from 5.5 to 7 mm. The primary outcome measure was the mean stromal ablation depth over the cone and was calculated for all possible scenarios. Results: In approach #1, the mean cone stromal ablation depths and ablation volumes were 49 ± 28, 58 ± 34, 68 ± 40, and 77 ± 46 µm, and 1,074 ± 626, 1,460 ± 863, 1,906 ± 1,113, and 2,448 ± 1,451 nl for an OZ of 5.5, 6, 6.5, and 7 mm, respectively ( P < .001). Approach #2 yielded mean depths and volumes of 33 ± 13, 38 ± 15, 44 ± 17, and 50 ± 19 μm, and 686 ± 266, 939 ± 371, 1,240 ± 489, and 1,592 ± 669 nl, respectively ( P < .001). In approach #3, the corresponding depths and volumes were 15 ± 6, 17 ± 7, 19 ± 7, and 21 ± 8 µm and 279 ± 89, 377 ± 118, 491 ± 146, and 626 ± 205 nl, respectively, across the same OZ range ( P < .001). There was a significant difference in mean cone stromal ablation depths and ablation volumes among the three approaches across all OZs, with approach #3 consistently demonstrating the lowest ablation depths and ablation volumes ( P < .001). Furthermore, the rate of increase in mean stromal ablation depth over the cone with expanding OZ size was minimal in approach #3. Conclusions: Treating only the sphere and cylinder embedded into the HOA ablation treatment profile leads not only to the slimmest ablation depth over the cone and ablation volume, but, more importantly, it provides the lowest increase in ablation depth with enlargement of the OZ.
PURPOSE:To evaluate the safety and efficacy of ray-tracing-guided laser in situ keratomileusis (LASIK) and to investigate the associations among visual line gain, higher order aberrations (HOAs), and manifest refraction spherical equivalent (MRSE). METHODS:This retrospective study enrolled 285 eyes of 143 participants who underwent ray-tracing-guided LASIK, and measurements including visual acuity, manifest refraction, and whole-eye aberrations at a 6-mm diameter pupil, with examinations performed preoperatively and at 1 day, 1 week, 1 month, and 3 months postoperatively. RESULTS:At 3 months postoperatively, 93.7% of eyes achieved uncorrected distance visual acuity (UDVA) of 20/20 or better, and 62.8% of eyes gained one or more visual lines of UDVA compared with preoperative corrected distance visual acuity (CDVA) (right eye: 62.9%; left eye: 62.7%). MRSE, astigmatism, astigmatism vectors, and HOAs were effectively corrected and well controlled. As UDVA improved postoperatively, trefoil decreased significantly compared with the pre-operative level (P < .01); in addition, eyes gaining one or more visual lines showed greater trefoil reduction and lower residual trefoil than eyes that did not gain (both P < .001). Notably, trefoil metrics did not differ across baseline MRSE strata, although the proportion of eyes with visual line gain decreased with increasing baseline MRSE. CONCLUSIONS:Ray-tracing-guided LASIK showed favorable safety, efficacy, predictability, and accuracy. Effective trefoil correction with low residual trefoil may be associated with visual line gain, and this association appears to be unaffected by the baseline MRSE distribution.
PURPOSE:To analyze trends and correlations in online public interest regarding four refractive procedures: laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), small incision lenticule extraction (SMILE), and Implantable Collamer Lens (ICL) (STAAR Surgical) implantation. METHODS:Monthly relative search volume (RSV) from Google Trends (Alphabet Inc) for terms "LASIK surgery," "SMILE surgery," "PRK surgery," and "ICL surgery" was collected in the United States from January 1, 2015 to October 1, 2025. RESULTS:"LASIK surgery" showed significantly greater search interest than PRK (10.3×), SMILE (14.8×), and ICL implantation (32.3×) (P < .001). Over the 10-year period, LASIK and PRK showed no significant changes in public interest (P > .05), whereas SMILE (r = 0.86) and ICL implantation (r = 0.81) demonstrated significant upward trends (both P < .001). However, subanalysis of the post-coronavirus disease 2019 period (March 2020 to October 2025) revealed a significant decline in LASIK search interest (r = -0.55; P < .001), whereas SMILE (r = 0.74) and ICL implantation (r = 0.84) continued to rise. PRK remained unchanged during this period. Search interest was strongly correlated between SMILE and ICL implantation (r = 0.80) and between PRK and LASIK (r = 0.59). Regionally, LASIK showed the highest RSV across most states, particularly above the national mean in the Midwest (Wisconsin and Iowa; z = 1.35) and the Northeast. Higher search interest was observed for PRK in Hawaii (z = 3.59), SMILE in Maryland (z = 3.12), and ICL implantation in Utah (z = 5.06). CONCLUSIONS:Despite LASIK's widespread popularity, search interest in SMILE and ICL implantation has increased during the past decade. Google Trends may be an effective tool for assessing shifting interest in refractive surgery modalities.
Purpose: To evaluate the clinical influence patterns of pre-operative chord mu and chord alpha on optical quality after Implantable Collamer Lens (ICL) (Visian; STAAR Surgical) implantation, thereby providing evidence-based guidance for surgical planning. Methods: This study included 92 patients (181 eyes) who underwent ICL implantation. The OPD-Scan III system (Nidek) was employed for the preoperative assessment of both chord mu and chord alpha. Changes in higher order aberrations were analyzed 3 months postoperatively. Postoperative optical aberration patterns were assessed for their dependence on preoperative chord mu and chord alpha measurements. Results: The mean value of chord mu was 0.25 ± 0.13 mm, and the median chord alpha was 0.22 mm (interquartile range: 0.19 mm). Chord mu exhibited a relatively dispersed distribution, whereas chord alpha was primarily distributed along the horizontal axis. Notably, 1/chord alpha exhibited a significant linear positive correlation with axial length ( R 2 = 0.1739, P < .001), reflecting the non-linear decay of chord alpha with axial elongation. The relationship was characterized by a generalized estimating equation using Gamma distribution and inverse link function. At 3 months postoperatively, analysis revealed statistically significant elevation in vertical coma and oblique trefoil ( P < .05), whereas other optical parameters including total higher order aberrations, primary coma, trefoil, spherical aberration, and horizontal coma remained stable ( P > .05). Correlation analysis revealed no significant association between changes in higher order aberrations and preoperative chord mu or chord alpha ( P > .05). Conclusions: Neither preoperative chord mu nor chord alpha significantly affects higher order aberrations after ICL implantation, suggesting that the procedure has a relatively high tolerance regarding chord mu and chord alpha selection.
Purpose: To evaluate patient-reported outcomes following wavefront-guided laser in situ keratomileusis (WGF-LASIK) and photorefractive keratectomy (WFG-PRK) performed by corneal fellows in training. Methods: In this prospective, nonrandomized clinical trial, 66 eyes of 33 patients underwent WFG-LASIK and 71 eyes of 36 patients underwent WFG-PRK at one institution. Main outcomes included results from the Patient-Reported Outcomes with LASIK (PROWL) questionnaire at the postoperative 3-month visit. Results: At 3 months postoperatively, self-reported worry related to vision (LASIK, P < .001; PRK, P < .001), work productivity ( P < .001 for both), and ability to perform activities (LASIK, P = .03; PRK, P < .001) significantly improved after surgery. The prevalence of double images, glare, halos, and starbursts decreased from 65% preoperatively to 56% in the LASIK group and from 74% preoperatively to 34% in the PRK group. Only 5% and 4% of participants reported “very” or “extremely bothersome visual symptoms in the LASIK and PRK groups, respectively, and no patients reported significant difficulty performing activities due to double images, glare, halos, or starbursts. Dry eye symptoms per Ocular Surface Disease Index score were similar preoperatively and at month 3 in both the LASIK and PRK groups. A total of 88.2% and 96.0% of participants were satisfied with their visual outcome after LASIK or PRK, respectively. Conclusions: WFG-LASIK or WFG-PRK performed by corneal fellows in training yielded marked improvements in the presence and severity of most visual symptoms. Vision-related quality of life metrics significantly improved, and overall satisfaction in this study was high.
PURPOSE:To evaluate whether a non-invasive approach to treat keratoconus with corneal cross-linking (CXL) using oral riboflavin and natural sunlight could represent a cost-effective alternative. METHODS:In a prospective, controlled study, 16 male New Zealand White rabbits (32 eyes) underwent a two-step protocol. Step 1 quantified stromal riboflavin in 4 rabbits (8 eyes) after 14 days of oral riboflavin (6 mg/kg/day). Step 2 randomized the remaining 12 rabbits (24 eyes) 1:1 to oral riboflavin plus natural sunlight or sunlight alone. After a 2,700 klux·h cumulative sunlight dose, corneal biomechanics were assessed by optical coherence tomography elastography and uniaxial stress-strain extensometry. RESULTS:The mean stromal riboflavin concentration after oral administration was 0.000081% ± 0.000011%. Stress-strain testing showed no significant differences in stress at 0.1 strain (152 ± 11.5 kPa in controls vs 146 ± 7.0 kPa in treated eyes; P = .57) or mean elastic modulus between 0.1 and 0.2 strain (4.1 vs 4.0 MPa; P = .870). OCT elastography demonstrated significantly higher posterior corneal strain in treated eyes (0.551‰ vs 0.398‰; P = .039), consistent with reduced apparent stiffness. CONCLUSIONS:Oral riboflavin combined with ambient sunlight did not induce corneal stiffening under the tested conditions. Stromal riboflavin levels were nearly 500-fold lower than those achieved with standard CXL, indicating the tested approach is unlikely to serve as an effective standalone cross-linking strategy. The observed posterior corneal stiffness reduction may reflect ultraviolet-A-induced stromal degradation or subthreshold photochemical effects rather than true cross-linking.
Purpose: To evaluate inter-device agreement of device-designated chord mu and chord alpha measurements, defined as device-designated linear displacements between the Purkinje reflex and the pupil center (chord mu) or limbal center (chord alpha), by four common devices: IOLMaster 700 (Carl Zeiss Meditec AG), Lenstar 900 (Haag-Streit), iTrace (Tracey Technologies), and Pentacam (Oculus Optikgeräte GmbH). Methods: This was a retrospective cross-sectional study of patients undergoing preoperative cataract evaluation at a tertiary academic center. Eyes with measurements from all four devices between 2020 and 2023 were included. Exclusion criteria included prior ocular trauma, surgery, or pathology affecting imaging. Chord mu and alpha were analyzed using bivariate methods, including centroid direction and inter-device comparisons. Biometry and corneal curvature were also analyzed. Results: A total of 110 eyes from 77 patients (mean age: 63 ± 11 years) were included. Across devices, mean chord mu values were approximately 0.35 ± 0.20 mm and mean chord alpha values were approximately 0.45 ± 0.23 mm, with substantial variability in both magnitude and orientation. Most pairwise inter-device comparisons demonstrated statistically significant differences for both chord mu and chord alpha. The IOLMaster 700 consistently demonstrated temporal centroid displacement and the widest directional dispersion, whereas other devices showed predominantly nasal centroid orientation. Left and right eyes demonstrated similar patterns but were analyzed separately. Conclusions: Clinically relevant inter-device differences in magnitude and orientation of chord mu and chord alpha were observed, with systematic centroid shifts and directional dispersion. These device-specific offsets indicate that such measurements are not interchangeable across platforms and should be interpreted in the context of the measuring device when applied to surgical planning.
Purpose: To systematically review visual outcomes, refractive predictability, astigmatic correction, and safety of SmartSight refractive surgery (SCHWIND eye-tech-solutions GmbH) for the correction of myopia and myopic astigmatism. Methods: A systematic search of six databases was conducted for studies published from 2020 onward. Peer-reviewed clinical studies reporting visual or refractive outcomes following SmartSight refractive surgery using the SCHWIND ATOS platform (SCHWIND eye-tech-solutions GmbH) were included. Study selection followed Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) 2020 guidelines. Risk of bias was assessed using the Joanna Briggs Institute checklist for case series. Due to heterogeneity in study design and outcome reporting, a narrative synthesis was performed. Results: Six studies comprising 877 eyes were included, all observational case series. Postoperative uncorrected distance visual acuity (UDVA) outcomes were favorable, with 59% to 98% of eyes achieving UDVA of 20/20 or better than preoperative corrected distance visual acuity. Refractive predictability ranging from 40% (postoperative day 1) to 98% (3 months) of eyes within ±0.50 diopters (D) and 89% to 100% within ±1.00 D of the intended spherical equivalent correction. Astigmatic correction was favorable, with ⩾96% of eyes achieving residual postoperative cylinder ⩽1.00 D from pre-operative mean cylinder ranging from 0.46 to 1.30 D across studies. Loss of two or more lines of corrected distance visual acuity was uncommon, and reported complications were predominantly mild and transient, occurring both intraoperatively (opaque bubble layer, suction loss) and postoperatively (epithelial defects, incision-related issues). Conclusions: SmartSight refractive surgery demonstrates favorable visual and refractive outcomes with an acceptable safety profile. However, current evidence remains early, derived mainly from case series with limited follow-up, potential conflicts of interest, and no randomized controlled trials. Further prospective and comparative studies are required to confirm long-term outcomes.
PURPOSE:To evaluate visual outcomes with particular attention to visual acuity of a segmental refractive multifocal intraocular lens, the ACUNEX VarioMax (Teleon Surgical). METHODS:This prospective, non-randomized, non-comparative study was conducted at the Department of Ophthalmology, University Hospital, Goethe University, Frankfurt, Germany. Thirty-four eyes (17 patients) were included. Inclusion criteria were bilateral cataract, age older than 30 years, and predicted corneal astigmatism ≤0.75 diopters (D) postoperatively. Exclusion criteria were prior ocular surgeries, amblyopia, or potential postoperative corrected distance visual acuity worse than 0.3 logarithm of the minimum angle of resolution (logMAR). Uncorrected visual acuities for distance, intermediate, and near and distance-corrected visual acuities at 4 m, 80 cm and 40 cm, contrast sensitivity, defocus curve, and questionnaires on optical quality, quality of life, and spectacle independence were assessed after 3 months. RESULTS:The mean monocular uncorrected distance visual acuity was 0.02 ± 0.09 logMAR at 4 m, uncorrected intermediate visual acuity was 0.15 ± 0.12 logMAR at 80 cm and uncorrected near visual acuity was 0.24 ± 0.10 logMAR at 40 cm. Defocus curve testing showed a distance-corrected binocular visual acuity range between 0.00 and -2.50 D (from -0.06 to 0.12 logMAR). Median contrast sensitivity under photopic and mesopic conditions was 1.48 ± 0.18 and 1.25 ± 0.29 logCS, respectively. CONCLUSIONS:This segmental multifocal intraocular lens provides good visual acuity at all distances, particularly providing good intermediate visual acuity and depth of focus. It showed good contrast sensitivity and high spectacle independence with a high degree of patient satisfaction.
PURPOSE:To evaluate the performance of artificial intelligence (AI)-based intraocular lens (IOL) power calculation formulas in eyes with extremely shallow anterior chambers (anterior chamber depth [ACD] < 2.5 mm). METHODS:This retrospective study enrolled 120 eyes of 120 patients with ACD < 2.5 mm who underwent phacoemulsification and IOL implantation. Seven AI formulas were evaluated: Hill-RBF 3.0, Kane, PEARL-DGS, LSF Al, Hoffer QST, Karmona, and Nallasamy. Subgroup analysis was performed based on lens thickness (LT). RESULTS:The Kane, PEARL-DGS, and Hoffer QST formulas exhibited no significant systematic bias (all P > .05) and demonstrated comparable refractive predictability in the overall cohort. In the thin lens subgroup (LT < 4 mm), the PEARL-DGS, LSF Al, and Hoffer QST yielded superior precision. In the intermediate subgroup (4 mm ⩽ LT < 5 mm), the Hill-RBF 3.0, Kane, and PEARL-DGS achieved higher accuracy. Notably, in eyes with pronounced lens-related crowding (LT ⩾ 5 mm), the Hill-RBF 3.0, Kane, and Hoffer QST remained the most reliable. CONCLUSIONS:Lens thickness is a critical determinant of refractive outcomes in eyes with extremely shallow ACD. Given that no individual AI-based formula maintains optimal predictive performance across the entire spectrum of lens morphology, a stratified formula selection strategy is recommended. Specifically, the PEARL-DGS is prioritized for thin lenses, Kane for intermediate profiles, and Hoffer QST for eyes with pronounced lens disproportion.
PURPOSE:To report clinical experience with a modified toric plate-haptic lens (VisTor; Hanita Lenses) also suitable for four-point scleral fixation in eyes without capsular support. METHODS:The commercial VisTor lens design was modified by adding two positioning holes in the lens haptic to facilitate four-point fixation. The lens axis was marked preoperatively, and the insertion points of the sutures were marked 2 mm from the limbus and 2 mm on each side of the toric marks. Polypropylene 6-0 or 7-0 sutures were inserted through the sclera and threaded through the designated holes in the intraocular lens (IOL) haptics. Four-point fixation was achieved by creation of four external flanges. RESULTS:Fifteen lenses were implanted in 15 eyes lacking capsular support. One patient was lost to follow-up and excluded from final analysis. The average age was 48 ± 22 years (range: 26 to 79 years). Surgery was secondary implantation in aphakia in 9 eyes, combined with crystalline lens removal in 3 eyes, and combined with IOL exchange in 3 eyes. The final position of the IOL was within 4 degrees of the planned axis in all eyes. No tilt was noted postoperatively and satisfactory visual improvement was achieved in all cases but one, in which vision loss was related to advanced glaucoma. CONCLUSIONS:Four-point scleral fixation of a plate-haptic IOL provides precise and stable IOL positioning with no tilt and accurate toric correction in eyes lacking capsular support.
PURPOSE:To characterize the demographic and topographic features of patients with keratoconus who developed hydrops after a prior treatment with corneal cross-linking (CXL). METHODS:Of the 4,967 eyes that had undergone accelerated epithelium-off CXL, acute hydrops occurred in 7 (0.14%) eyes of 7 patients in the follow-up period. Analysis of demographic and topographic features was performed. RESULTS:The median age was 19 years (range: 17 to 23 years) and the male-to-female ratio was 5:2. The median mean keratometry (Km) was 57.70 diopters (D) (range: 51.80 to 60.70 D), maximum keratometry (Kmax) was 62.50 D (range: 55.10 to 68.10 D), and minimum pachymetry was 422 microns (range: 390 to 456 microns) before the CXL. The location of cone was central in all 7 eyes. At the visit preceding the occurrence of hydrops, the median Km was 54.50 D (range: 52.80 to 63.40 D), Kmax was 62.30 D (range: 57.40 to 79.00 D), and the minimum pachymetry was 375 microns (range: 313 to 404 microns). The median time from CXL to occurrence of hydrops was 39.3 months (range: 18.9 to 59.1 months). Although clinically there was flattening and reduction in pachymetry noted, there was no statistically significant difference in the keratometry and pachymetry values from baseline to after CXL. No significant antecedent history of coughing, sneezing, or eye rubbing could be elicited. CONCLUSIONS:The occurrence of hydrops after CXL is rare. Eye rubbing associated with allergic conditions is the specific predisposition. A clinically noteworthy feature was a reduction in pachymetry in eyes that developed hydrops. Due to the rarity of hydrops following prior CXL, reporting this event and reviewing the clinical and topographic features may enhance understanding in future studies.
PURPOSE:To assess the optical bench performance of a novel non-diffractive, wavefront-shaping intraocular lens (IOL) optimized for near vision (PF), and to evaluate its complementary use with its companion extended depth of focus (EDOF) model in the Balanced Extended Vision Procedure (BEVPx; AST VisionCare, Inc). METHODS:A preclinical comparative study was conducted using the PMTF device (Lambda-X Ophthalmics) to measure modulation transfer function (MTF) through-focus at 50 lp/mm in accordance with International Organization for Standardization (ISO) standard 11979-2:2014. Visual performance was further assessed by United States Air Force target imaging at multiple pupil sizes. Defocus curves were computed from MTF data to predict functional visual acuity. Optical performance was evaluated for PF and EDOF lenses (AST VisionCare, Inc) both individually and in combination, to simulate binocular outcomes in the BEVPx approach. RESULTS:Both IOLs demonstrated equivalent distance vision performance. The EDOF lens provided superior intermediate optical quality, whereas the PF lens enhanced near-visual performance beyond +2.50 diopters without loss of distance acuity. Simulated defocus curves revealed a dual-peak profile for the PF lens, maintaining predicted visual acuity better than 0.2 logarithm of the minimum angle of resolution across distance-to-near vergences. Combining the two lenses yielded a continuous defocus curve with functional vision across the entire range, supporting the rationale of the BEVPx strategy. CONCLUSIONS:The PF IOL introduces a non-diffractive solution for extending vision into the near range, and may provide a full range of high-quality vision with reduced risk of photic phenomena, both alone and in combination with the EDOF lens. Preclinical evidence supports the BEVPx approach as a promising strategy to bridge the gap between EDOF and trifocal IOL designs.
PURPOSE:To compare the refractive prediction accuracy of two modern toric intraocular lens power formulas, using predicted or measured posterior corneal astigmatism, in eyes with a history of previous myopic laser vision correction (LVC). METHODS:This retrospective case series included 182 eyes with a history of previous myopic LVC that underwent uncomplicated cataract surgery with implantation of a monofocal non-toric IOL. Preoperative biometry was performed with swept-source optical coherence tomography. Spherical equivalent and refractive astigmatism prediction accuracy of the Barrett True K Toric and Emmetropia Verifying Optical (EVO) Toric formulas, using predicted posterior corneal astigmatism (PPCA) or measured posterior corneal astigmatism (MPCA), was analyzed using vector analysis and the Eyetemis online tool (https://eyetemis.com/). RESULTS:For spherical equivalent prediction accuracy, the EVO Toric formula with MPCA had the highest proportion of eyes within ±0.50 diopters (D) (68%) and the lowest mean absolute error (0.419 D). The trimmed mean spherical equivalent prediction error for Barrett True K MPCA was significantly smaller than for Barrett True K PPCA (P < .01). With respect to refractive astigmatism, there was no significant difference in the absolute refractive astigmatism prediction error for EVO PPCA compared to EVO MPCA (P = .89). However, the refractive astigmatism prediction error for Barrett PPCA was smaller than for Barrett MPCA (P < .01). CONCLUSIONS:Measured posterior corneal astigmatism improves the prediction accuracy of both the EVO and Barrett True K toric formulas with respect to the spherical equivalent but has a detrimental effect on the refractive astigmatism prediction accuracy of the Barrett True K toric formula.
