Custom Ablation Research Articles

Thermal ablation with configurable shapes: a comprehensive, automated model for bespoke tumor treatment

BackgroundMalignant tumors routinely present with irregular shapes and complex configurations. The lack of customization to individual tumor shapes and standardization of procedures limits the success and application of thermal ablation.MethodsWe introduced an automated treatment model consisting of (i) trajectory and ablation profile planning, (ii) ablation probe insertion, (iii) dynamic energy delivery (including robotically driven control of the energy source power and location over time, according to a treatment plan bespoke to the tumor shape), and (iv) quantitative ablation margin verification. We used a microwave ablation system and a liver phantom (acrylamide polymer with a thermochromic ink) to mimic coagulation and measure the ablation volume. We estimated the ablation width as a function of power and velocity following a probabilistic model. Four representative shapes of liver tumors < 5 cm were selected from two publicly available databases. The ablated specimens were cut along the ablation probe axis and photographed. The shape of the ablated volume was extracted using a color-based segmentation method.ResultsThe uncertainty (standard deviation) of the ablation width increased with increasing power by ± 0.03 mm (95% credible interval [0.02, 0.043]) per watt increase in power and by ± 0.85 mm (95% credible interval [0, 2.5]) per mm/s increase in velocity. Continuous ablation along a straight-line trajectory resulted in elongated rotationally symmetric ablation shapes. Simultaneous regulation of the power and/or translation velocity allowed to modulate the ablation width at specific locations.ConclusionsThis study offers the proof-of-principle of the dynamic energy delivery system using ablation shapes from clinical cases of malignant liver tumors.Relevance statementThe proposed automated treatment model could favor the customization and standardization of thermal ablation for complex tumor shapes.Key points• Current thermal ablation systems are limited to ellipsoidal or spherical shapes.• Dynamic energy delivery produces elongated rotationally symmetric ablation shapes with varying widths.• For complex tumor shapes, multiple customized ablation shapes could be combined.Graphical

Simultaneous Topography-guided Custom Ablation With Corneal Cross-linking for Keratoconus: 10-Year Prospective Outcomes

Purpose: To assess 10-year visual and tomographic outcomes of topography-guided custom ablation (T-CAT) with corneal cross-linking (CXL) in eyes with keratoconus. Methods: T-CAT with CXL was performed in 600 eyes (522 patients). Based on the T-CAT ablation plan, the theoretical maximum ablation depth was 50 µm after epithelium removal. After ablation, accelerated corneal cross-linking (CXL) was performed in the central 8-mm zone (9 mW/cm 2 for 10 minutes in “epi-off” mode). The visual acuity and tomography were assessed. Results: There was significant improvement in uncorrected ( P = .001) and corrected ( P = .001) distance visual acuity after the procedure. Keratometry, root mean square lower order aberrations and higher order aberrations, defocus, coma 90°, and spherical aberration reduced significantly after surgery at 10 years of follow-up ( P &lt; .005). All Pentacam (Oculus Optikgerate GmbH) tomographic variables showed significant changes indicating regularization after T-CAT ( P &lt; .005). Flattening of greater than 5.00 diopters in maximum keratometry was noted in 6 eyes (1%). Two of 600 eyes progressed postoperatively and required repeat CXL. Conclusions: T-CAT plus CXL is a safe and effective technique even in the long term for regularizing the anterior corneal surface with significant visual improvement and reduction in higher order corneal aberrations. [ J Refract Surg . 2023;39(11):759–766.]

Refractive outcomes and optical quality of PRESBYOND laser-blended vision for presbyopia correction.

To investigate the one-year refractive outcomes and optical quality following PRESBYOND laser-blended vision (LBV). This retrospective study included 20 patients who underwent PRESBYOND treatment between Jan 2019 and Aug 2020. The patients were asked to attend a follow-up outpatient visit one year after surgery. Distance and near visual acuity as well as subjective refraction were examined. Optical quality was assessed using wavefront-supported custom ablation. A questionnaire evaluating optical quality and satisfaction was completed at the last visit. The average patient age was 48.1±7.4y (range, 41 to 58y). The mean preoperative spherical equivalent was -7.59±2.39 D. At the one-year follow-up, two eyes (both dominant eyes) lost one line of corrected distance visual acuity (CDVA), while the remaining eyes (38/40) maintained or gained lines of CDVA. The average binocular uncorrected distance visual acuity improved from 0.15±0.03 to 0.90±0.26 (decimal vision; P<0.001). The average binocular uncorrected near visual acuity increased from 0.34±0.28 to 0.97±0.07 (P<0.001). The spherical aberration was 0.04±0.06 µm in the nondominant eye and 0.09±0.09 µm in the dominant eye (P=0.02). All patients were satisfied with or accepted the outcomes of the surgery. The primary complaints were related to disturbances in night vision and relatively inferior near vision. Over the one-year observation period, PRESBYOND is a safe and effective option for presbyopia correction. The optical quality and near vision deserve further investigation.

Vision Quality Questionnaire Assessment in Patients After Topography-Guided Photorefractive Keratectomy for Irregular Astigmatism Secondary to Radial Keratotomy.

AimTo evaluate the vision-related quality of life with the National Eye Institute Refractive Error Quality of Life (NEI-RQL) questionnaire in patients with astigmatism secondary to radial keratotomy surgery who underwent topography-guided photorefractive keratectomy.MethodsProspective non-randomized clinical trial. This study included 15 patients (30 eyes) aged > 21 years, mean age 55.1 (SD, 3.5) years, 53.3% female, with astigmatism ≤ - 6.00 D resulting from radial keratotomy, which could have been associated with hyperopia ≤ + 6.00 D. Photorefractive keratectomy with topography-guided custom ablation treatment was used in all cases. The patients answered the NEI-RQL questionnaire preoperatively and at 4 and 48 months after topography-guided photorefractive keratectomy. The following data were collected: age, sex and education level, pre-operative refraction data, visual acuity with or without correction, pachymetry, and keratometry.ResultsThere was a significant difference between pre-and postoperative NEI-RQL scores for the domains clarity of vision, near vision, far vision, diurnal fluctuation, activity limitations, glare, symptoms, correction dependence, appearance, and satisfaction with correction (p < 0.001).ConclusionTopography-guided photorefractive keratectomy improved vision-related quality of life in patients with a history of irregular astigmatism secondary to radial keratotomy.

Customized Ablation Area PTK as a Treatment for Limewater-induced Calcium Carbonate Corneal Deposits

PURPOSE: To describe a customized ablation area photo-therapeutic keratectomy (CAA-PTK) technique to accurately match and ablate an area of calcific deposits using a laser ablation profile matching the slit-lamp findings. METHODS: A chronic non-healing epithelial defect was induced by limewater injury from a stalactite. The calcific deposits eroding the corneal anterior stromal layer were refractory to medical therapy and ulcer bed debridement. CAA-PTK tailored to exactly match the pathology dimensions was performed. RESULTS: Complete epithelial healing was observed the next day with unaltered visual acuity (corrected distance visual acuity 20/20 - ). One month postoperatively, corneal optical coherence tomography showed a healed epithelial defect with epithelial thickening over the ablated area. The patient was followed up for 2 years with no signs or symptoms of corneal erosions. CONCLUSIONS: CAA-PTK application in treating potential corneal denaturation with overlying non-healing epithelial defects refractory to stromal bed debridement is promising. Unlike conventional PTK, CAA-PTK avoids unnecessary epithelial and stromal ablation, leading to faster visual recovery. [ Journal of Refractive Surgery Case Reports. 2022;2(2):e38–e42.]

Comparison of Corneal Optical Quality After SMILE, Wavefront-Optimized LASIK and Topography-Guided LASIK for Myopia and Myopic Astigmatism.

PurposeTo compare visual outcomes and corneal optical quality after small incision lenticule extraction (SMILE), wavefront-optimized (WFO) FS-LASIK, and topography-guided customized ablation treatment (TCAT) FS-LASIK for myopia.MethodsThis prospective case-series study included 283 eyes of 283 myopic patients who underwent SMILE or FS-LASIK. There were 102, 100, and 81 eyes in the SMILE group, WFO group and TCAT group, respectively. The tomography system (Sirius) was used to measure corneal aberrations and optical quality.ResultsAt postoperative 1 and 6 months, there were no significant differences in uncorrected distance visual acuity and corrected distance visual acuity among the three groups (P > 0.05). Postoperative manifest refractive spherical equivalent was similar among the groups (P > 0.05). There was statistically significant difference in cylinder at 1 month among the three groups, with the highest mean value in TCAT group (P < 0.05). The corneal optical path difference, root mean square of corneal astigmatism and strehl ratio were the most superior in the TCAT group at postoperative 1 and 6 months (P < 0.05).ConclusionSMILE, WFO FS-LASIK, and TCAT FS-LASIK provided similar visual results. The corneal visual quality after TCAT FS-LASIK was the best.

Macular phototoxicity after corneal crosslinking

Introduction: Keratoconus is a progressive degenerative corneal disease of variable severity. Its management includes medical and surgical treatment. Corneal crosslinking (CXL) is being increasingly used to stabilize the condition. Macular phototoxicity is a well-known side effect of light exposure; however, its incidence after treatment with riboflavin and UV light is unknown. This study reported the clinical features of a patient with macular phototoxicity after UV-A exposure and described the structural and angiographic retinal changes observed in the patient. Patient, Clinical Findings, and Diagnosis: A 37-year-old man with keratoconus underwent corneal refractive surgery (topography-guided custom ablation with accelerated and high-fluence CXL). Postoperatively, he had decreased vision in the operated eye. Ophthalmoscopy, spectral-domain optical coherence tomography, and fluorescein angiography revealed retinal pigment epithelial changes, ellipsoid zone disruption, and window defects, respectively. The patient was diagnosed with macular phototoxicity. The corrected distance visual acuity stabilized at 20/100 after 6 months. Conclusions: Macular phototoxicity may occur after UV-A exposure during CXL. The use of accelerated and high-fluence protocols might have contributed to its occurrence in this patient.

Scheimpflug imaging of the anterior segment following simultaneous cross-linking with topography-guided custom ablation treatment for keratoconus.

To report alterations in the anterior segment following accelerated corneal collagen cross-linking and topo-guided customized ablation treatment with the Nidek vision excimer laser system (Nidek Co., Ltd., Gamagori, Japan) in a single procedure. We reviewed the medical records of patients who underwent cross-linking for progressive keratoconus. We divided patients into four groups based on the treatment protocol. Eyes were evaluated regarding uncorrected distance visual acuity, corrected distance visual acuity, keratometry (maximum [Kmax], equivalent keratometry readings, Ksteep and Kflat parameters), corneal elevations (anterior and posterior), the anterior radius of curvature, the posterior radius of curvature, anterior chamber volume, anterior chamber depth, anterior chamber angle and the pachymeter of the thinnest locale of the cornea before the surgery and at 1, 3, 6, and 12 months after the procedure. We included 259 eyes of 227 patients with progressive keratoconus who underwent treatment. The mean respective baseline uncorrected distance visual acuity and corrected distance visual acuity were: 0.68 ± 0.45 and 0.34 ± 0.40 in Group 1; 0.82 ± 0.44 and 0.33 ± 0.23 in Group 2; 0.61 ± 0.36 and 0.21 ± 0.17 in Group 3; and 0.65 ± 0.38 and 0.23 ± 0.18 in Group 4; logMAR did not show significant difference among the groups (p=0.14 and p=0.06, respectively). Visual improvements were better in the combined surgery groups. Mean Kmax in Groups 1, 2, 3, and 4 were 57.24 ± 7.51, 59.26 ± 6.94, 53.73 ± 4.60, and 54.31 ± 4.25 diopter (D), respectively. Group 1 demonstrated increased Kmax for 6 months. Maximum flattening by 3.38 ± 2.35 D 1 year after surgery was observed in Group 4 (p<0.05). Decreased anterior chamber angle, anterior chamber depth, and anterior chamber volume were similar, indicating the stability of the anterior chamber. Visual and anatomical improvement is better, with improved stability of the anterior segment, in combined surgery groups compared with cross-linking alone.

Topography-Guided Versus Wavefront-Optimized LASIK for Myopia With and Without Astigmatism: A Meta-analysis.

To evaluate the differences in efficacy, predictability, safety, and visual quality between topography-guided customized ablation treatment (TCAT) and wavefront-optimized (WFO) laser in situ keratomileusis (LASIK) for the treatment of myopia with and without astigmatism. A comprehensive literature search of PubMed, Embase, the Cochrane library, Web of Science, and ClinicalTrials was used to identify randomized controlled trials (RCTs) comparing TCAT-LASIK with WFO-LASIK for myopia with and without astigmatism up to September 2020. The references of all searched literature were checked as supplements. Literature was screened according to the inclusion and exclusion criteria and relative data were extracted. RevMan software version 5.3.0 (Cochrane Collaboration) was used for meta-analysis. A total of seven RCTs (1,168 eyes) were included. There were no statistically significant differences in the ratio of uncorrected distance visual acuity of 20/20 or better (relative risk [RR] = 1.01, 95% CI [0.97 to 1.06], P = .64) and 20/16 or better (RR = 0.96, 95% CI [0.80 to 1.16], P = .69). Compared with WFO-LASIK, TCAT-LASIK achieved a higher proportion of postoperative manifest refractive spherical equivalent within ±0.50 diopters of the target (RR = 1.06, 95% CI [1.02 to 1.11], P = .003) and less surgically induced higher order aberrations (weighted mean difference [WMD] = -0.11, 95% CI [-0.15 to -0.0], P < .00001), spherical aberrations (WMD = -0.04, 95% CI [-0.05 to -0.03], P < .00001), and coma (WMD = -0.15, 95% CI [-0.28 to -0.01], P = .03). No patient lost two or more lines of distance-corrected visual acuity postoperatively in the two groups. This meta-analysis suggests that both TCATLASIK and WFO-LASIK show excellent efficacy, predictability, and safety for myopia. TCAT-LASIK exhibited more accurate postoperative refraction predictability and less surgically induced higher order aberrations, spherical aberrations, and coma. More randomized, prospective, and large sample-sized studies are needed to confirm these conclusions in the long term. [J Refract Surg. 2021;37(10):707-714.].

Topography-guided corneal surface laser ablation combined with simultaneous accelerated corneal collagen cross-linking for treatment of keratoconus

Backgroundto study the outcomes of topography-guided customized excimer laser subepithelial ablation combined with accelerated CXL for progressive keratoconus.MethodsThirty-one eyes of 30 patients with progressive keratoconus were included in this prospective study. Topography-guided excimer laser ablation without refractive correction was performed. Simultaneous accelerated collagen cross-linking with ultraviolet light of 30 mW/cm2 for 4 min was followed. Uncorrected distance visual acuity (UCVA), manifest refraction, corrected distance visual acuity (CDVA), tomograghy were examined at postoperative 1, 6, and 12 months.ResultsUDVA improved slightly after surgery (P > 0.05). BSCDVA improved significantly from 0.32 ± 0.20 logMAR to 0.15 ± 0.14 logMAR at postoperative 12 months (P < 0.05). During 12-month follow-ups, there were no significant differences in manifest refraction and corneal keratometry except for maximal keratometry value of the anterior surface (Kapex), which decreased significantly from 57.23 ± 5.09D to 53.13 ± 4.47D (P < 0.05). Even though the thinnest corneal thickness decreased from 465 ± 24 μm to 414 ± 35 μm (P < 0.05), curvature asymmetry index front (SIf), keratoconus vertex front (KVf) and Baiocchi Calossi Versaci index front (BCVf) decreased significantly till postoperative 12 months (P < 0.05). Corneal higher-order aberrations and coma also decreased significantly till 12 months after surgery (P < 0.05).ConclusionsTopography-guided surface ablation without refractive correction combined with simultaneous accelerated collagen cross-linking provided good stability in refraction and corneal curvature, and also showed significant improvement in BSCDVA, corneal regularity and corneal optical quality.

Topography guided custom ablation treatment for residual refractive error after keratoplasty

To evaluate the efficacy and safety of topography-guided custom ablation photorefractive keratectomy (TCAT) in treating residual refractive error and astigmatism after keratoplasty. Medical records of all patients who underwent TCAT from 2013 to 2017 for residual refractive error and irregular astigmatism after keratoplasty were reviewed. Data were collected on patient demographics, surgical details and preoperative and 6 months postoperative refraction, corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA) and keratometry indices. The procedure was comprised of two stages where stage-1 was aimed at decreasing the irregular astigmatism and stage-2 at correcting the refractive error. Stage 2 was only performed if the corneal parameters including residual stromal bed were within acceptable limits. Forty-six eyes of 46 patients were included. Nineteen eyes underwent stage-1 TCAT treatment only (Group-1). Nine eyes underwent stage-2 TCAT six months after the stage 1 (Group-2) and 18 eyes underwent a simultaneous stage 1 and 2 procedure (Group-3). Six months following TCAT, CDVA improved in 69.6% This success rate was 63.2% in Group-1, 44.4% in Group-2 and 88.9% in Group-3. Median spherical equivalent (SE) decreased from −4.5D preoperatively to −2.5D postoperatively and the median cylinder decreased from 3.25D preoperatively to 2.43D postoperatively. Comparing to Group-2, eyes in Group-3 experienced larger reduction in SE and astigmatism. Treatment of patients with post-keratoplasty residual refractive error and astigmatism with TCAT resulted in successful outcomes with improvements CDVA and UDVA. Performing a simultaneous two-stage TCAT procedure appeared to be more effective in reducing the refractive error.

Accuracy of WASCA Aberrometer Refraction Compared to Manifest Refraction and Cycloplegic Refraction in Hyperopia Measurement.

PurposeTo explore the agreement between the wavefront supported custom ablation (WASCA) aberrometer and manifest refraction (MR) and cycloplegic refraction (CR) in hyperopia testing.MethodsNinety eyes of 90 hyperopic patients (spherical equivalent ≥ +0.5 D) were evaluated; MR, CR, and WASCA refraction (WR) were performed consecutively. Analysis pupil size was 6.0 mm in WASCA measurement using the Seidel method. The conventional notation was transferred into vector components for analysis, i.e., spherical equivalent (M) and two cross-cylinders at axis 0° (J0) and axis 45° (J45). Bland-Altman plots were used to test the agreement between the two measurements.ResultsThe mean Ms obtained with MR and CR were 3.23 ± 1.74 D and 4.04 ± 2.04 D, respectively (P < 0.001), and the correlation was high (r = 0.90, P < 0.001). The WR was highly correlated with MR and CR in terms of M (r = 0.89, 0.87), but not significantly correlated in J0 and J45. The total dioptric power vector error was 0.18 ± 1.00 D between WR and MR and −0.64 ± 1.03 D between WR and CR. The limits of agreement of all vector components were beyond ± 1.0 D. With hyperopia level increase, WR tended to overestimate MR (P = 0.04), whereas WR always underestimated CR.ConclusionsWASCA could act as a reference of subjective refraction in hyperopia measurement, the exchangeability is not fully applicable.Translational RelevanceWASCA can provide an alternative for objective refraction in hyperopia measurement.

Mutual comparative analysis: a new topography-guided custom ablation protocol referencing subjective refraction to modify corneal topographic data

BackgroundSeveral planning algorithms have been developed for topography-guided custom ablation treatment (T-CAT), but each has its own deficiencies. The purpose of this study is to demonstrate the potential of a novel mutual comparative analysis (MCA) informed by manifest refraction and corneal topographic data and the patient’s subjective perception in correcting ametropia.MethodsThis retrospective review included patients with significant preoperative differences in the power or axis of astigmatism according to the manifest refraction and corneal topographic data (power > 0.75 D and/or axis > 10°). T-CAT planning was designed using MCA. Follow-ups were conducted for at least 6 months.ResultsSeventy-nine patients (121 eyes) were included. The mean preoperative deviation in the astigmatic power and axis were 0.72 ± 0.43 D and 20.18 ± 23.68°, respectively. The average oculus residual astigmatism (ORA) was 0.81 ± 0.32 D (range: 0.08–1.66 D). Six months postoperatively, the mean spherical equivalent refraction was 0.04 ± 0.42 D, and the mean cylinder was − 0.27 ± 0.24 D. The mean efficacy and safety indices were 1.10 and 1.15, respectively. The uncorrected distance visual acuity in 92% of the eyes was the same or better than the corrected distance visual acuity. The angle of error was ±5° in 61% of eyes and ± 15° in 84% of eyes. Residual astigmatism was ≤0.5 D in 91% of eyes. Optical quality and photopic contrast sensitivity did not change significantly (p > 0.05), and the scotopic contrast sensitivity decreased at 3, 6, and 12 cpd (p < 0.05). The vertical coma and horizontal coma of the anterior corneal surface significantly decreased postoperatively but increased during follow-up.ConclusionsThe MCA demonstrated safety, efficacy, accuracy, predictability, and stability and can be used as a complementary and feasible method for T-CAT.

Optimized refractive surgery in keratoconus

Purpose: The aim of the study is to compare the refractive results after simultaneous TransPRK and Cross-linking procedure for treatment of keratoconus with optimized and non-optimized customized ablation profiles; to introduce the concept of optimization in keratoconus and discuss its clinical significance; to find predictive factors for better refractive outcomes in simultaneous combined procedures and to propose therapeutic algorithm. Methods: Syrius schimpflug aberrometer (Schwind) was used to create non-optimized custom and optimized custom ablation profiles in keratoconic corneas. TransPRK ablation was performed with Schwind Amaris Eximer Laser (500 Hz). Cross-linking was done with Avedro cross-linking suit. Analysis of preoperative and postoperative refraction, visual acuity, keratometric and aberometric data was done for both groups. Correlative analysis of the preoperative and postoperative variables was done with Pierson statistical analysis. Results: 44 patients (70 eyes), age 19-67, 29 eyes with optimization, 41 eyes without optimization were followed for 18 months. A positive correlation was found between CCT and the amount of postoperative flattening in patients over 40 years of age. No correlation was found with Kavg. Conclusions: Long term results after simultaneous TransPRK + Cross linking show stability and safety. Optimization of refraction brings better refractive results compared to non-optimized procedure. It can be safely performed in thinner corneas and compensates for the hypermetropic shift generated by the cross-linking procedure.

Customized laser vision correction for irregular cornea post-refractive surgery.

Ablation-related complications following the refractive procedures are a major challenge for a refractive surgeon, considering the elective nature of the procedure. The use of topography-guided customized ablation has revolutionized the management of irregular corneas postrefractive surgery. This preferred practice highlights various hurdles encountered while managing cases of decentered ablation, small ablation zones, and planning a cataract surgery in patients with irregular corneas. It will give insight to the refractive surgeon on the planning of corneal regularization on various modern-day refractive platforms available, such as the WaveLight® EX-500 (Alcon Laboratories, Inc., Fort Worth, TX, USA), Schwind Amaris 1050 (Peramis; SCHWIND eye-tech-solutions, Kleinostheim, Germany), and Technolas Teneo 317 model 2 excimer laser (Bausch & Lomb, Rochester, NY, USA). The algorithmic approach outlined will enable the refractive surgeon to choose between the wavefront optomized and the topography-guided ablations.

Transepithelial Topography-Guided Ablation Assisted by Epithelial Thickness Mapping for Treatment of Regression After Myopic Refractive Surgery

To evaluate the outcomes of transepithelial, topography-guided, epithelial mapping-assisted ablation in the treatment of regression after myopic refractive surgery. A retrospective consecutive case series of 70 eyes of 52 patients with regression after previous corneal refractive surgery for treatment of myopic and compound myopic astigmatism underwent re-treatment using transepithelial topography-guided and epithelial mapping-assisted custom ablation with a wide and smooth transition zone design. The ablation profile was based on data from corneal topography, whereas the epithelial ablation depth was decided by corneal epithelial mapping obtained by optical coherence tomography. The mean follow-up time after re-treatment was 13.6 ± 9.4 months (range: 6 to 51 months). At the patients' last follow-up visit, 98.5% and 76.5% had uncorrected distance visual acuity of 20/40 and 20/20 or better. Safety and efficacy indexes were 1.05 and 0.92, respectively. The mean spherical equivalent was reduced from -1.10 ± 0.65 to -0.16 ± 0.34 diopters. Both total root mean square, odd-order, and even-order higher order aberrations improved significantly (P = .021, .040, and .030, respectively), whereas corneal asphericity remained unchanged (P = .662). Epithelial thickness profile showed significant smoothing between the central 2-mm and 2- to 5-mm paracentral areas. Transepithelial topography-guided and epithelial mapping-assisted custom re-treatment with a wide and smooth transition zone design is safe and effective for addressing myopic regression in patients who have previously undergone myopic refractive surgery. [J Refract Surg. 2019;35(8):525-533.].

Topography-guided ablation for the treatment of irregular astigmatism

# Purpose Refractive surgery promotes good quality of vision without optical correction in most cases. Conventional ablation has reduced effectiveness in irregular corneas, where custom ablations are usually a better option. We have evaluated the results of visual acuity and refraction in patients undergoing custom topography-guided ablation. # Setting Oftalmocentro, Porto Alegre – RS – Brazil. # Design This is a case series, retrospective, non-comparative study. # Methods We studied 60 eyes from 48 patients who underwent topography guided customized refractive surgery, from October 2013 to September 2017, performed with excimer laser Schwind Amaris 750. # Results Mean age was 44.2 years, being most men (56.6%). Patients with penetrating keratoplasty (PKP) encompassed 36.6% (n = 22), previous radial keratotomy (RK) 20.0% (n = 12), previous deep anterior lamellar keratoplasty (DALK) 16.6% (n = 10) and 26.5% (n = 16) with other diagnoses. Topo-guided surgeries were trans-photorefractive keratectomy (trans-PRK) (41.5%), femto laser-assisted in situ keratomileusis (femto-LASIK) (35.0%), laser-assisted in situ keratomileusis (LASIK) (11.6%) and photorefractive keratectomy (PRK) (11.6%). Cylinder refraction decreased from −3.91 D (±2.00) to −1.45 D (±1.43) (p < 0.01). The spherical equivalent (SE) decreased from −2.04 D (±1.85) to −0.65 D (±1.03) (p < 0.01). Best spectacle-corrected visual acuity (BSCVA) improved in 65% of eyes, from 0.55 (±0.23) to 0.69 (±0.24) (p < 0.01). Follow-up of 40 eyes from 30 patients demonstrated that the effect of the procedure was maintained during the studied period (24,45 ± 14,14 months). # Conclusion Topography-guided ablation is safe and effective in reducing corneal irregularities, leading to an improvement in visual acuity in 2/3 of cases.

Incidence and Outcomes of Optical Zone Enlargement and Recentration After Previous Myopic LASIK by Topography-Guided Custom Ablation.

To report the incidence, visual and refractive outcomes, optical zone enlargement, and recentration using topography-guided CRS-Master TOSCA II software with the MEL 80 excimer laser (Carl Zeiss Meditec AG, Jena, Germany) after primary myopic laser refractive surgery. Retrospective analysis of 73 eyes (40 patients) with complaints of night vision disturbances due to either a decentration or small optical zone following a primary myopic laser refractive surgery procedure using the MEL 80 laser. Multiple ATLAS topography scans were imported into the CRS-Master software for topography-guided ablation planning. The topography-guided re-treatment procedure was performed as either a LASIK flap lift, a new LASIK flap, a side cut only, or photorefractive keratectomy. Axial curvature maps were analyzed using a fixed grid and set of concentric circles superimposed to measure the topographic optical zone diameter and centration. Follow-up was 12 months. The incidence of use in the population of myopic treatments during the study period was 0.79% (73 of 9,249). The optical zone diameter was increased by 11% from a mean of 5.65 to 6.32 mm, with a maximum change of 2 mm in one case. Topographic decentration was reduced by 64% from a mean of 0.58 to 0.21 mm. There was a 44% reduction in spherical aberration, 53% reduction in coma, and 39% reduction in total higher order aberrations. A subjective improvement in night vision symptoms was reported by 93%. Regarding efficacy, 82% of eyes reached 20/20 and 100% reached 20/32 (preoperative CDVA was 20/20 or better in 90%). Regarding safety, no eyes lost two lines of CDVA and 27% gained one line. Regarding predictability, 71% of re-treatments were within ±0.50 diopters. Topography-guided ablation was effective in enlarging the optical zone, recentering the optical zone, and reducing higher order aberrations. Topography-guided custom ablation appears to be an effective method for re-treatment procedures of symptomatic patients after myopic LASIK. [J Refract Surg. 2018;34(2):121-130.].

Contoura Vision – laserowa korekcja wad wzroku o najwyższym stopniu personalizacji

Personalised laser vision correction procedures are the next step in refractive surgery development. They date back to the late nineties of the twentieth century. Customized ablation treatments are based on wavefront analysis of the optical system of the eye (aberrometry) or on corneal topographical maps. Nowadays, topography-guided custom ablation treatment supersedes the wavefront-guided technique, which is affected by more variables in the eye anatomy. The topography-guided procedure for virgin eyes is called ContouraTM Vision.

MRI-Guided Robotically Assisted Focal Laser Ablation of the Prostate Using Canine Cadavers.

a magnetic resonance imaging (MRI)-conditional needle guidance robot is developed to enhance MRI-guided focal laser ablation (FLA) therapy in patients with focal prostate cancer. inspired by the workflow of the manual FLA therapy, we developed an MRI-conditional robot with two degrees of freedom to provide the guidance for laser ablation catheter. This robot is powered by pneumatic turbine motors and encoded with the custom-designed optical encoder. The needle could be inserted manually through the designed robotic system, which keeps the patients inside MRI bore throughout the procedure. The robot hardware is integrated with the custom ablation planning and monitoring software (OncoNav) to provide an iterative treatment plan to cover the whole ablation zone. Virtual tumors were selected in three canine cadavers as targets to validate the performance of the proposed hardware and software system. phantom studies show that the average targeting error is less than 2 mm and the workflow of the entire procedure lasts for 100minutes. Canine cadaver experiment results show that all the targets were successfully ablated in no more than three administrations. MRI-guided prostate FLA is feasible using the proposed hardware and software system, indicating potential utility in future human trials.