Topography-guided Ablation Research Articles

Comparison of Outcomes after Wavefront-optimized and Topography-guided Transepithelial Photorefractive Keratectomy.

To evaluate the outcomes of wavefront-optimized (WFO) and topography-guided (TG) transepithelial photorefractive keratectomy (transPRK) in the treatment of myopia and myopic astigmatism. Patients who underwent transPRK using the WaveLight EX500 excimer laser for the correction of myopia and myopic astigmatism between January 2022 and March 2023 were divided into groups of WFO transPRK (77 eyes of 36 patients) or TG transPRK (63 eyes of 31 patients) in this retrospective, observational cohort study. The preoperative and postoperative 3-month refractive and visual outcomes of the two groups were analyzed. In both groups, the uncorrected distance visual acuity was 0.0 logarithm of the minimum angle of resolution or better in 95% of eyes 3 months postoperatively, and the mean manifest refraction spherical equivalent was within ±1.0 diopter in 90% of eyes. No significant differences were observed between the groups in terms of the uncorrected distance visual acuity or astigmatism. A significant induction of higher order aberrations (HOAs) was observed in both groups. However, the induction of total corneal HOAs (p = 0.014) and spherical aberrations (p < 0.001) was significantly lower in the TG group than that in the WFO group. WFO and TG transPRK effectively improved the visual and refractive outcomes; however, the induction of total corneal HOAs and spherical aberration was lesser following the TG ablation.

Treatment of irregular astigmatism by topography-guided ablation

Treatment of irregular astigmatism by topography-guided ablation

The Impact of Epithelial Remodeling on Surgical Techniques Used in Topography-guided Surface Ablation in Irregular Corneas.

To analyze the optical consequences of epithelial remodeling in irregular corneas and their impact on the choice of different surface ablation techniques. Anterior corneal and stromal surface topographies and epithelial thickness maps were analyzed in 24 eyes with irregular corneal optics. On two of the eyes, four different surface ablation techniques were simulated: (1) conventional anterior topography-guided photorefractive keratectomy (PRK), (2) transepithelial phototherapeutic keratectomy (PTK), (3) transepithelial anterior topography-guided PRK, and (4) stromal topography-guided PRK. Stromal surface topographies showed higher keratometric values, astigmatism, asphericity, and corneal higher order aberrations compared to topographies of anterior corneas covered by epithelium. Transepithelial anterior topography-guided PRK and stromal topography-guided PRK both resulted in regularized stromal surface, transepithelial PTK achieved partial regularization corresponding to the smoothing effect of the epithelial remodeling, and conventional anterior topography-guided PRK delivered after epithelial removal resulted in residual stromal surface irregularities. The difference in optical landscapes between the stromal and anterior surfaces in irregular corneas will represent a source of error when anterior topography-guided treatments are delivered on the deepithelialized stroma, as in conventional PRK. In contrast, anterior topography-guided ablations performed as transepithelial PRK and stromal topography-guided PRK delivered after epithelial removal address the full stromal irregularity, whereas transepithelial PTK alone may be used when topography-guided treatments are not possible. The authors conclude topography-guided PRK of irregular corneas should lead to significantly improved regularization only if it includes the effect of epithelial remodeling. [J Refract Surg. 2022;38(8):529-537.].

Ten-Year Outcome of Topography-Guided Transepithelial Surface Ablation for Refractive Myopia Treatment.

To evaluate 10-year long-term refractive visual stability and participants' satisfaction in the refractive treatment of myopic eyes undergoing topography-guided transepithelial surface ablation using a 1KHz excimer laser. This single-center prospective survey assessed participants' satisfaction 10 years after the treatment using a non-validated questionnaire with regards to visual outcome, dry eye, and visual disturbance symptoms. Pre- and postoperative visual and refractive data were evaluated. Of 106 participants (54% females) with a mean patient age of 36 (± 8.6) years, 166 eyes were included. Mean preoperative spherical equivalent (SE) was - 4.23 (± 2.48) diopters (D). Uncorrected distant visual acuity (UCVA) after 10 years was ≥ 1.0 (Snellen) in 92% of the eyes. Manifest SE was within ± 1.0 D of the desired refraction in 86% of the eyes after 10 years. Mean quality of life (QOL) improvement was high (9.15 out of 10 points). Dry eye symptoms were reported by 35 out of 104 (34%) patients. Visual symptoms like halos or starbursts were reported by 24 out of 101 (24%) and 12 out of 100 (12%) patients, respectively. Topography-guided transepithelial surface ablation for myopia provided stable long-term results in terms of UCVA and SE. Participant satisfaction was high, with only low rates of dry eye or visual symptoms.

Visual differences in topography-guided versus wavefront-optimized LASIK in the treatment of myopia: a Meta-analysis.

To investigate the potential differences between topography-guided (TG) and wavefront-optimized (WFO) laser in situ keratomileusis (LASIK) for the treatment of myopia. A systematic literature search was performed to determine relevant trials comparing LASIK with TG and WFO from the time of library construction to August 2020, and The PubMed, Cochrane, Web of Science, EMBASE and Chinese databases (i.e. CNKI, CBM, WAN FANG and VIP) were accessed. The data on visual acuity, refractive status and wavefront aberration were retrieved and evaluated from three to six months after surgery. STATA (version 14.0) software was used for statistical analysis. A cumulative Meta-analysis was simultaneously performed. Eleven studies with a total of 1425 eyes were incorporated. No statistically significant differences were evident between TG and WFO ablation in the proportion of eyes achieving an uncorrected distance visual acuity (UCVA) of 20/20 or better (P=0.377), gaining one line or more (P=0.05), postoperative cylinder (P=0.40), vertical coma (P=0.593) and horizontal coma (P=0.957). After TG ablation, the proportion of the patients' eyes of which postoperative refraction is within ±0.5 diopter of the target refraction was significantly higher than that undergoes WFO (P=0.003). As opposed to the WFO group, manifest refraction spherical equivalent (MRSE; P=0.000) was lower, and UCVA (P=0.005) was better in the TG group. The higher-order aberrations (HOAs; P=0.000), spherical aberration (P=0.000) and coma (P=0.000) were significantly lower in TG group. The cumulative Meta-analysis illustrated that the proportion of eyes achieving UCVA of 20/20 or better, postoperative refraction within ±0.5 diopter, and MRSE has steady between the two groups. Both TG-LASIK and WFO-LASIK are safe, effective, and predictable for correcting myopia. TG-LASIK may produce fewer aberration and is more precise than WFO-LASIK.

Topography-Guided Trans-Epithelial No-Touch Photorefractive Keratectomy for High Irregular Astigmatism After Penetrating Keratoplasty: A Prospective 12-Months Follow-Up.

PurposeTo describe the efficacy and safety of topography-guided trans-epithelial no-touch photorefractive keratectomy (PRK) for the correction of highly irregular astigmatism after penetrating keratoplasty (PK).Patients and MethodsA prospective study was conducted on 12 eyes of 12 patients affected by highly irregular astigmatism after PK for keratoconus. Each patient underwent a single-step topography-guided trans-epithelial ablation (CIPTA®2 software, iVis Technologies). Corneal topography data as well as uncorrected (UDVA) and corrected distance visual acuity (CDVA) and spherical equivalent (SEQ) were collected preoperatively (T0) and at 1 (T1), 3 (T2) and 12 (T3) months after surgery.ResultsMean UDVA and CDVA significantly improved, respectively, from 1.22±0.17 and 0.18±0.03LogMAR at T0 to 0.63±0.17 (CI 95%, P<0.001) and 0.04±0.03LogMAR at T3 (CI 95%, P<0.001). Mean SEQ significantly decreased from −3.75±1.32 to –1.60±1.32D (CI 95%, P<0.02). Mean subjective refractive astigmatism (SRAST) and mean keratometry astigmatism (SimK) significantly decreased, respectively, from 7.83±0.98 and 8.10±1.48D to 2.83±0.98 and 5.29±1.48D (CI 95%, P<0.001). Corneal Morphological Irregularity index (CMI) significantly decreased from 62.76±7.26 µm to 23.24±7.26 µm (CI 95%, P<0.001). Apart from a single episode of graft rejection 5 days after ablation, successfully reverted with topical steroids, no other complications were noted. A mild corneal haze was observed in two eyes (16.7%) at 3 months post-PRK, and no regression was observed at 12 months.ConclusionOur study demonstrates the safety and long-term effectiveness of a trans-epithelial topography-guided ablation in the treatment of post-PK highly irregular astigmatism.

Combined transepithelial PTK and topography-guided PRK for treatment of trauma-related corneal scarring

Corneal scars can severely impair visual performance and treatment can be challenging. The study aimed to evaluate apromising minimally invasive option in the treatment of corneal scars using transepithelial topography-guided ablation. This retrospective interventional study involved four eyes of four patients who developed corneal scarring and irregular surfaces due to trauma and were treated with topography-guided photorefractive keratectomy (TG-PRK) between 2017 and 2020. The ablation profile was calculated in all four cases using CRS-Master (Zeiss, Jena, Germany). The main outcome measures were uncorrected and best-corrected distance visual acuity, manifest refraction and corneal regularity by topographic images. The mean age was 34.75 ± 15.39years and the follow-up time was 6 months for all patients. In three cases full subjective refraction was corrected in one session and one patient had arefractive error of +0.5D. Only corneal surface smoothing without additional refractive correction was performed in this case. All four patients showed improvement in uncorrected (2-3Snellen lines) and corrected (3Snellen lines) distance visual acuity. No complications occurred during or after the treatment and there was no reduction of visual acuity in any case. The use of TG-PRK in patients with corneal scarring improves visual acuity in selected cases. In myopic patients most of the refractive error can also be corrected in asingle session.

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.

Intraoperative Swept-Source OCT-Based Corneal Topography for Measurement and Analysis of Stromal Surface After Epithelial Removal.

To assess intraoperative stromal topography measurements using swept-source optical coherence tomography (OCT)-based topography/tomography after epithelial removal and to analyze the epithelial contribution to the corneal topography and optics. This was a prospective series of 22 eyes of 19 patients referred to receive phototherapeutic keratotomy (PTK) for treatment of recurrent corneal erosion and a control group of 22 virgin eyes. Swept-source OCT corneal topography/tomography was obtained immediately before and immediately after mechanical deepithelialization before PTK. Epithelial thickness maps were obtained before the surgery using spectral-domain OCT in the control group and as a reference in the group with anterior basement membrane dystrophy. Topographic and optical characteristics, including the curvature, astigmatism, asphericity, and higher order aberrations of the cornea before and after deepithelialization were compared, and their differences correlated with the measurements derived from the epithelial thickness maps. Stromal topography measurements after deepithelialization were easily obtained and showed excellent repeatability. Assessment of corneal edema induced by deepithelialization revealed that it did not significantly affect the measured parameters. The stromal surface was steeper by 1.28 diopters, had higher with-the-rule astigmatism by 0.41 diopters, was more prolate, and had more higher order aberrations compared to the intact epithelialized corneal surface. These differences correlated well with the parameters derived from epithelial thickness maps. Measurement of stromal topography using swept-source OCT immediately after mechanical deepithelialization may be a viable method in therapeutic refractive surgery, where stromal topography-guided ablation is needed. A significant epithelial contribution to anterior corneal topography and optics was confirmed. [J Refract Surg. 2021;37(7):484-492.].

Coma Influence on Manifest Astigmatism in Coma-Dominant Irregular Corneal Optics

To evaluate the influence of coma on manifest refractive cylinder (MRC) in eyes with coma-dominated corneal optics and suggest alternative guidelines for surgical planning of astigmatism correction in topography-guided ablation and toric intraocular lens (IOL) exchange surgery. Twelve eyes with coma-dominant corneal optics and low lenticular astigmatism were selected. The astigmatism remaining after subtraction of total corneal astigmatism (TCA) and lenticular astigmatism from MRC, termed discrepant astigmatism, was calculated and correlated to corneal coma at the anterior surface. Refractive and topography data were then used to simulate topography-guided refractive surgery (topography-guided group) in 7 eyes and lenticular exchange surgery with toric intraocular lens (IOL) implantation (toric IOL group) in 5 eyes. The estimated postoperative MRC after correction of TCA or MRC for each group was compared. The axis and amplitude of discrepant astigmatism correlated strongly with the axis and amplitude of coma. In the topography-guided group, where topography-guided ablation eliminated corneal higher order aberrations (HOAs), TCA-based correction led to less estimated postoperative manifest astigmatism than MRC-based correction. In the toric IOL group, where removal of the crystalline lens did not affect corneal HOAs, MRC-based correction via toric IOL implantation led to less estimated postoperative astigmatism than TCA-based correction. Discrepant astigmatism in eyes with coma-dominant corneal optics correlates with coma. In such eyes, treating TCA, along with corneal HOAs, instead of MRC, seems appropriate in topography-guided treatments, whereas treating MRC may be a better choice in lenticular exchange surgery with toric IOL implantation, where corneal HOAs are not treated. [J Refract Surg. 2021;37(4):274-282.].

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.

Primary Topography-Guided LASIK: Refractive, Visual, and Subjective Quality of Vision Outcomes for Astigmatism ⩾2.00 Diopters.

To evaluate the outcomes of primary topography-guided laser in situ keratomileusis (LASIK) in eyes with subjective refractive astigmatism of 2.00 diopters (D) or greater. This was a prospective study in consecutive eyes with cylinder of 2.00 D or greater that had LASIK using the Alcon WaveLight EX500 excimer laser and T-CAT/Contoura software (Alcon Laboratories, Inc., Fort Worth, TX). The accuracy, efficacy, safety, cylinder vector analysis, higher order aberrations, and patients' subjective quality of vision were assessed. Eyes with naturally occurring topographic irregular astigmatism were not excluded. The mean cylinder was -2.55 D preoperatively and -0.34 D postoperatively; 81% and 95% of eyes were within ±0.50 and ±0.75 D of intended cylinder after LASIK, respectively. The correction index and index of success were 1.00 and 0.13, respectively. The efficacy and safety indexes were 0.98 and 1.04, respectively. The preoperative corneal topography irregularity index, anterior corneal higher order aberrations, and refractive astigmatism magnitude were mildly correlated to postoperative residual astigmatism. Mean ocular and corneal coma were not increased postoperatively. Patients had significant improvements after LASIK in both subjective uncorrected quality of vision and night vision disturbances compared to spectacle- and contact lens-corrected vision before LASIK. Topography-guided ablation using the Alcon WaveLight EX500 excimer laser and T-CAT/Contoura software results in excellent accuracy, efficacy, and safety, with improved postoperative subjective quality of vision and reduced night vision disturbances in virgin eyes with refractive astigmatism of 2.00 D or greater, including eyes with topographic naturally occurring irregular astigmatism. [J Refract Surg. 2019;35(2):78-86.].

Topography-Guided Custom Photorefractive Keratectomy for Myopia in Primary Eyes With the WaveLight EX500 Platform.

To evaluate the outcomes after topography-guided ablation treatment (T-CAT) for the correction of myopia and myopic astigmatism with photorefractive keratectomy (PRK). This was a retrospective, non-comparative case series study of 25 patients (40 eyes) with low to moderate myopia with or without astigmatism who underwent topography-guided custom PRK with the Wave-Light EX500 excimer laser platform (Alcon Laboratories, Inc., Fort Worth, TX). The customized treatment plan was based on Topolyzer Vario topography system (Alcon Laboratories, Inc.) data. The patients were observed for 6 months after the procedure. The surgery significantly reduced the manifest refractive spherical equivalent (MRSE), sphere, and cylinder (P < .05) at 6 months of follow-up. Compared with the preoperative corrected distance visual acuity (CDVA), 8 (20%) and 10 (25%) of 40 eyes gained one or more lines of postoperative uncorrected distance visual acuity at 3 and 6 months, respectively. Only 1 eye presented loss of one line of CDVA at 6 months postoperatively, which was due to delayed epithelial healing. Ten patients (15 eyes) reported symptoms related to dry eye and the vision of 21 patients (17 eyes) fluctuated during the first month. The T-CAT custom PRK procedure provided good early outcomes for treating patients with low to moderate myopia with or without astigmatism. [J Refract Surg. 2018;34(8):541-546.].

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.].

Topography-Guided Ablations: Early US Experience and Utility Across the Refractive Landscape

This paper evaluated topography-guided excimer ablations and recent US experience of this technology. Personal clinical experience, initial approval of the technique, and its application to a potential extended spectrum of clinical conditions was reviewed. Topography-guided ablation can precisely treat corneas with variable topographic indices and attempt to neutralize irregularities by combining myopic and hyperopic ablation profiles. The T-CAT Phase III study demonstrated the safety and efficacy of this technique, which earned FDA approval in 2013. Current literature has reinforced its efficacy and explored off-label investigations, such as its use to improve visual results in abnormal corneas (e.g., keratoconus, post-LASIK ectasia). Topography-guided ablation provides increased quality of vision without necessitating excess tissue removal in otherwise normal, keratoconic, ectatic, or post-corneal transplant eyes. In the future, we will likely see a combination of treatment strategies, enabling ophthalmologists to treat the entire refractive surface and refine these already remarkable results.

Assessment of refractive astigmatism and simulated therapeutic refractive surgery strategies in coma-like-aberrations-dominant corneal optics

BackgroundThe aim of the study is to raise the awareness of the influence of coma-like higher-order aberrations (HOAs) on power and orientation of refractive astigmatism (RA) and to explore how to account for that influence in the planning of topography-guided refractive surgery in eyes with coma-like-aberrations-dominant corneal optics.MethodsEleven eyes with coma-like-aberrations-dominant corneal optics and with low lenticular astigmatism (LA) were selected for astigmatism analysis and for treatment simulations with topography-guided custom ablation. Vector analysis was used to evaluate the contribution of coma-like corneal HOAs to RA. Two different strategies were used for simulated treatments aiming to regularize irregular corneal optics: With both strategies correction of anterior corneal surface irregularities (corneal HOAs) were intended. Correction of total corneal astigmatism (TCA) and RA was intended as well with strategies 1 and 2, respectively.ResultsAxis of discrepant astigmatism (RA minus TCA minus LA) correlated strongly with axis of coma. Vertical coma influenced RA by canceling the effect of the with-the-rule astigmatism and increasing the effect of the against-the-rule astigmatism. After simulated correction of anterior corneal HOAs along with TCA and RA (strategies 1 and 2), only a small amount of anterior corneal astigmatism (ACA) and no TCA remained after strategy 1, while considerable amount of ACA and TCA remained after strategy 2.ConclusionsComa-like corneal aberrations seem to contribute a considerable astigmatic component to RA in eyes with coma-like-aberrations dominant corneal optics. If topography-guided ablation is programmed to correct the corneal HOAs and RA, the astigmatic component caused by the coma-like corneal HOAs will be treated twice and will result in induced astigmatism. Disregarding RA and treating TCA along with the corneal HOAs is recommended instead.

Laser Vision Correction in Treating Myopia.

Myopia is a generally benign refractive error with an increasing prevalence worldwide. It can be corrected temporarily with glasses and contact lenses and permanently with laser vision correction. The 2 main procedures currently being performed for myopia correction are photorefractive keratectomy and laser-assisted in situ keratomileusis. Each technique has its advantages, but they appear to yield similar visual outcomes 1 year after surgery. Laser vision correction for myopia was considered a paradigm shift because healthy eyes could now undergo a surgical procedure to permanently and safely correct the error by altering the center of the cornea, which was previously off limits because of the potential for loss of transparency. Customized ablation using wavefront aberrometry and its optimized profiles were created to correct higher-order aberrations and give more vision quality to patients. Topography-guided ablation, initially used for complex retreatments, shows potential to make vision even better than glasses and contact lenses in a recent study on previously untreated eyes. One major concern is to identify corneas that are at risk of developing ectasia after the procedure. Topographic and tomographic screening indices have been implemented clinically, but there is still much to learn about corneal biomechanics. A more recently developed procedure for myopia correction is small-incision lenticule extraction, in which a lenticule is created in the cornea's stroma with a femtosecond laser and extracted through a small corneal incision. Long-term outcomes and new complication risks need to be better understood as this procedure develops.

Simultaneous Topography-guided Surface Ablation with Collagen Cross-linking for Keratoconus

ABSTRACT Purpose In this article, we present the results of eight eyes of patients who underwent combined same-day partial topography-guided surface ablation followed by accelerated collagen cross-linking (CXL) procedure at Care-Vision Laser Centers to achieve stabilization of corneal ectasia and enhance visual rehabilitation in keratoconus. Materials and methods A retrospective nonrandomized review of 8 eyes of 6 patients who underwent the Athens Protocol for progressive keratoconus. Each patient underwent topography-guided ablation followed by CXL procedure. Follow-up Follow-up was done on day 1, day 7, and then at 1, 3, 6, and 12 months. Results There was a rapid and significant improvement in uncorrected visual acuity and best-corrected visual acuity in 100% eyes, a reduction of keratometric values, and symmetry between vertical hemimeridians. Topographic evaluation showed a marked improvement in irregularity. There were no signs of keratoconic progression noted in any of the eyes on last follow-up. No adverse events were reported in any patient. Conclusion Simultaneous surface ablation + CXL seems to be a promising treatment capable of offering patients functional vision and halting progression of the disorder. Precis Simultaneous topography-guided custom ablation treatment and photorefractive keratectomy with CXL offers keratoconic patients intolerant to contact lenses both stabilization of the cornea and improved functional vision with spectacles correction. How to cite this article Karmona L, Sela T, Franco O, Shoshani A, Munzer G, Kaiserman I. Simultaneous Topography-guided Surface Ablation with Collagen Cross-linking for Keratoconus. Int J Kerat Ect Cor Dis 2016;5(2):71-76.