Topography-guided Photorefractive Keratectomy Research Articles

Combined photorefractive keratectomy and corneal collagen cross-linking for treatment of keratoconus: a 2-year follow-up study.

Background:Corneal collagen cross-linking (CXL) is considered an effective procedure for slowing down or eliminating the progression of keratoconus. New techniques, in combination with CXL, have been proposed to stop the evolution of keratoconus and improve the visual function.Objective:To evaluate the effectiveness of combined photorefractive keratectomy (PRK) with mitomycin-C (MMC) application and CXL in the management of grade 1–2 keratoconus over a 2-year follow-up.Methods:Fifteen eyes underwent topography-guided PRK with 0.02% MMC application immediately followed by standard CXL.Results:Best corrected visual acuity improved from 0.15 ± 0.11 logMAR to 0.08 ± 0.09 logMAR at 24 months (p < 0.0001) in treated eyes. Mean steepest meridian keratometry reduced from 48.79 ± 3.22 D at baseline to 46.16 ± 3.11 D at 24 months (p < 0.0001). Mean flattest meridian keratometry reduced from 45.18 ± 2.17 D preoperatively to 44.35 ± 2.19 D at 24 months (p < 0.0001).Conclusion:Simultaneous topography-guided PRK with MMC 0.02% application and standard CXL is a safe, promising and effective procedure in the treatment of mild and moderate keratoconus.

Concordance of keratoconus in monozygotic twins before and after combined corneal crosslinking/photorefractive keratectomy (Athens Protocol) using Scheimpflug and OCT tomography.

To describe the concordance of keratoconus (KC) expression in 2 pairs of monozygotic twins before and after a combined corneal crosslinking (CXL)/photorefractive keratectomy (PRK) procedure. Private ambulatory eye surgery unit. Retrospective interventional twin study. Two pairs of male monozygotic twins with KC were studied retrospectively. Improvement of flattest (K1) and steepest (K2) keratometry, index of height decentration (IHD), and corneal thickness at the thinnest point and corneal epithelial thickness measured by anterior segment optical coherence tomography and Scheimpflug tomography was compared between respective eyes of monozygotic twin siblings 1 to 5 years after the application of combined CXL and topography-guided PRK of part of the refractive error (the Athens Protocol). Significant improvement was noted in all the keratometric indices of all 8 eyes after the combined CXL/PRK procedure. The difference in K1, K2, IHD, corneal thickness at the thinnest point, and corneal epithelial thickness percentage improvement between the right eyes of each pair of twins was statistically significant 1 year and 5 years postoperatively (P < .05). Statistically significant discordance in the aforementioned parameters percentage improvement was similarly observed between the left eyes of each pair of twins (P < .05). Although a genetic predisposition in KC is well documented, the discordance in keratometric indices improvement after a CXL/PRK procedure between respective eyes of monozygotic twins suggests that environmental influences may contribute to the disease expression as well. Variable degree of synergy in a combined CXL/PRK procedure may also explain the aforementioned discordant improvement.

Assessment of the quality of information on treatment of keratoconus on YouTube

To evaluate the reliability, quality and effectiveness of YouTube videos addressing treatment of keratoconus. This is a retrospective, cross-sectional and register-based study. A YouTube search was performed using the keyword treatment of keratoconus, and the first 100 videos that came out were included in the study. The numbers of views, likes, dislikes, comments, daily viewing rate (number of views per day), uploaded source (physicians, public or private institution, health channel or patients), country of origin, video type (patient experience, scholarly information), and described treatment technique (contact lens, corneal cross-linking, intrastromal corneal ring, topography-guided photorefractive keratectomy, keratoplasty) were evaluated for all videos. They were also evaluated regarding their DISCERN, Journal of the American Medical Association (JAMA), global quality score (GQS) and usefulness score by two independent ophthalmologists. Of the top 100 videos, 83 videos met the criteria. The mean DISCERN, JAMA, GQS and usefulness score were 42.92 ± 18.14, 2.7 ± 0.73, 3.07 ± 1.25 and 2.99 ± 1.44, respectively. Of the 83 videos, 35(42.2%) had been uploaded by physicians, 19(22.9%) by patients, 15(18.1%) by health channel, and 14(16.9%) by institutions/private health institutions. In the correlation analysis, the four scoring systems showed a statistically significant and strong positive correlation with each other (p < 0.001). In addition, viewing rate DISCERN, GQS, usefulness scores, number of likes, dislikes and comments showed a statistically significant positive correlation. The content of YouTube videos regarding treatment of keratoconus is of generally good quality and is educational for patients. Increasing the number of videos uploaded by healthcare professionals will increase the quality, reliability and informative features of the videos.

New treatment algorithm for keratoconus and cataract: small-aperture IOL insertion with sequential topography-guided photorefractive keratectomy and simultaneous accelerated corneal crosslinking.

To describe a new treatment algorithm aimed at optimizing refractive outcomes for patients with keratoconus and cataract. Private practice in Sydney, Australia. Retrospective case series. This procedural approach involves cataract extraction with small-aperture intraocular lens (IOL) insertion, IC-8 IOL (AcuFocus, Inc.), followed by topography-guided photorefractive keratectomy (T-PRK) with simultaneous corneal crosslinking (CXL). Cataract surgery was performed with an initial 2.4 mm clear corneal incision enlarged to 3.5 mm to accommodate IC-8 IOL insertion. Once eyes demonstrated stable corneal tomography and refraction, T-PRK was performed using Schwind excimer laser (500 Hz) with the Vancouver custom topographical neutralization technique, aiming to achieve low myopia. CXL was performed immediately after T-PRK using Optolink hypotonic riboflavin with LIGHTLink-CXL (Lightmed) with 5.4 J total energy delivered at an 18 mw/cm2 irradiance. Outcomes of 4 eyes are reported with all achieving rigid gas-permeable (RGP) contact lens independence, improved corrected distance visual acuity (CDVA) and uncorrected distance visual acuity (UDVA), and regularization of corneal curvature with cone reduction. The mean CDVA improved from 0.43 preoperatively to 0.07 postoperatively (P = .00), and the mean UDVA improved from 0.81 preoperatively to 0.29 postoperatively (P = .04). Postoperative UNVA ranged from N.8 to N.12. This treatment algorithm demonstrates unique combination of existing corneal and cataract surgical procedures to achieve satisfactory refractive outcomes and RGP contact lens independence in patients with keratoconus and cataract.

Selective transepithelial ablation with simultaneous accelerated corneal crosslinking for corneal regularization of keratoconus: STARE-X protocol.

To evaluate the changes in refractive outcomes and corneal aberrations in central and paracentral keratoconus after selective transepithelial topography-guided photorefractive keratectomy combined with accelerated corneal crosslinking (STARE-X). Centro Polispecialistico Mediterraneo, Siena Crosslinking Center, and University of Messina, Italy. Prospective, interventional, multicentric study. Patients were subdivided into 2 groups: Group 1 with cone located within the central 3 mm zone (50 eyes) and Group 2 (50 eyes) with cone located outside the central 3 mm zone. Follow-up was 2 years at least for all eyes. Outcome parameters included uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA). Corneal tomography and corneal wavefront aberrations were assessed and compared before and 2 years after the treatment. 100 eyes of 100 patients underwent STARE-X protocol. At 2 years, UDVA and CDVA improved, and sphere, cylinder, and Kmax reduced after treatment in both groups (P < .001, respectively). Moreover, a statistically significant reduction was observed of total higher-order aberrations root main square (RMS), coma RMS, and spherical aberration RMS in both groups (P < .001, respectively). However, CDVA improved more in Group 1 than in Group 2 (P < .02). The STARE-X protocol demonstrated effective results in halting keratoconus progression and improving corneal regularity with a safe and effective profile. STARE-X improved both visual acuity and corneal aberration at 2 years. Longer follow-up studies are warranted to observe further long-term CXL flattening effect on the cone.

Estabilidade do Tratamento de Queratocone Combinado com Crosslinking Associado a Queratectomia Fotorrefrativa com Laser Excimer

Introduction: The purpose of this study is to evaluate the stability of crosslinking (CXL) treatment associated with photorefractive keratectomy (PRK) with excimer laser in patients with keratoconus, through comparison of keratometric and topographic parameters and functional results at 6 months postoperatively and at the last evaluation. Methods: Seventy-four eyes of 71 patients with established kerotoconus who had contact lens intolerance and/or disease progression were included. The eyes were submitted to CXL plus partial PRK and a residual stromal thickness of 325 μm in the end of the laser procedure was required. We compared uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), refractive sphere and cylinder, keratometric parameters (K1, K2, Kmax, average K) and minimum pachymetry at 6 months and at last evaluation. Results: The mean age was 32.12±9.73 years. We report the results at 6 months and last evaluation (occurred between 12 and 37 months postoperatively), mean 17.09±6.39 months. All parameters (K1, K2, average K, maximum K, K1 axis, spherical equivalent and minimum pachymetry) remained stable, except for BCVA which improved 0.05 logMAR (p<0.05). No patient lost more than two lines of Snellen chart and the greatest improvement was five lines. Conclusion: Our results suggest that accelerated CXL with topography-guided PRK in keratoconic eyes resulted in progressive BCVA improvement between 6 months and 12 to 37 months postoperatively. Keratometric and topographic values remained stable postoperatively, confirming the efficacy of the procedure in arresting progression of keratoconus.

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.

Simultaneous Topography-Guided PRK/CXL Versus Topography-Assisted PTK/CXL: 1-Year Prospective Outcomes in Keratoconic Eyes.

To compare 1-year visual and tomographic outcomes of topography-guided photorefractive keratectomy (TGPRK) and topography-assisted phototherapeutic keratectomy (TPTK) with corneal cross-linking (CXL). TGPRK and TPTK were performed in 72 eyes (68 patients) and 74 eyes (71 patients), respectively. Based on the TGPRK ablation plan, the eyes underwent TPTK where the theoretical minimum corneal thickness (MCT) after surgery was less than 400 µm. In the TGPRK group, the theoretical maximum ablation depth was 50 µm after epithelium removal. In TPTK, a decentered single-step PTK was performed only in the steepest anterior curvature zone and the stromal ablation depth was limited to 25 µm. After ablation, accelerated CXL was performed in the central 8-mm zone (9 mW/cm2 for 10 minutes in "epithelium-off" mode) in both TGPRK and TPTK. The visual acuity and tomography were assessed. Improvement in uncorrected (P = .73) and corrected (P = .66) distance visual acuity was similar between the two groups. However, TGPRK eyes had a greater decrease in keratometry, anterior defocus, and spherical aberration (P < .001) at the cost of greater ablation of tissue (P < .001). The median MCT decreased by 27 and 52.5 µm in the TPTK and TGPRK eyes, respectively. Both groups had similar decreases in anterior root mean square of lower (P = .10) and higher (P = .12) order aberrations. Both TGPRK and TPTK improved visual acuity in the keratoconic eyes at 1 year of follow-up. However, TPTK removed less volume of tissue. Further, it could be an alternative to TGPRK if the theoretical stromal ablation exceeds 50 µm in thin keratoconic corneas. [J Refract Surg. 2021;37(8):562-569.].

Comparison of safety and efficiency of corneal topography-guided photorefractive keratectomy and combined with crosslinking in myopic correction: An 18-month follow-up.

To compare the safety and efficiency of simple corneal topography-guided (T-CAT) photorefractive keratectomy (PRK) and T-CAT PRK combined with crosslinking (CXL) to correct myopia with borderline suspicious tomography.Eyes with suspicious tomography (not classified as forme fruste keratoconus) underwent PRK combined with CXL. The suspicious tomography showed irregular posterior corneal morphology or maximum elevation value of the central 6 mm zone of the posterior surface (MEL) >15 μm, or Belin/Ambrósio Enhanced Ectasia Index (BAD-D) was >1.6. The PRK group was generated and matched within 2 μm for MEL, 0.3 for BAD-D value, and 0.5 D for manifest refractive spherical equivalent (MRSE) compared with the PRK-CXL group.PRK-CXL exhibited a larger MRSE (0.09 ± 0.22 D vs −0.03 ± 0.24 D, P = .02) and a larger sphere (0.14 ± 0.22 D vs 0.01 ± 0.21 D, P = .002) compared with PRK alone at 18 months postoperatively. The magnitude change and relative change rate of stiffness parameter A1 in the PRK-CXL were smaller than in the PRK group (−15.72 ± 14.56 vs −19.95 ± 14.37, P = .04, for magnitude change and −0.16 ± 0.15 vs −0.20 ± 0.14, P = .02, for relative change rate). In the PRK-CXL and PRK groups, 4.8% and 6.9% of eyes suffered grade 0.5 haze at postoperative 18-month. No cases of ectasia were reported in either group.PRK in combination with prophylactic crosslinking showed comparable safety and efficacy, but higher biomechanical stability compared to PRK alone, thus, the additional CXL plays a measurable role in reducing the change in corneal biomechanical properties after PRK in suspicious eyes.

Topography-Guided Photorefractive Keratectomy for Postkeratoplasty Astigmatism: Long-Term Outcomes.

To evaluate the long-term efficacy and safety of topography-guided photorefractive keratectomy (TG-PRK) for postkeratoplasty refractive error correction. A retrospective interventional case series of 54 eyes of 50 patients who underwent previous corneal transplants. Unaided distance visual acuity (UDVA) and best corrected visual acuity (CDVA), manifest refraction, mean central keratometric value, mean keratometric astigmatism, and postoperative complications were reviewed. Final follow-up was at mean 31 (±17) months. Sixteen point seven percent of eyes underwent more than 1 surface ablation. Mean UDVA improved from 0.96 ± 0.06 logarithm of the minimum angle of resolution (LogMAR) preoperatively to 0.46 ± 0.05 LogMAR of resolution at the final follow-up (Bonferroni, P < 0.0001). Mean UDVA improved by 4.4 Snellen lines. Improvement in CDVA was not significant, although a significant improvement was noted when eyes with preoperative CDVA <20/40 were analyzed separately (t test, P = 0.005). Mean astigmatism improved from -4.4 ± 0.26 D preoperatively to -2.4 ± 0.26 D at the final follow-up (Bonferroni, P < 0.0001), whereas mean SEQ improved from -2.5 ± 0.39 D preoperatively to -1.1 ± 0.25 D (Bonferroni, P = 0.02). In total, 9% at the preoperative visit and 55% at the final visit had less than 2 D of astigmatism, respectively. Keratometric astigmatism decreased from 5.24 ± 0.36 D preoperatively to 2.98 ± 0.34 D at the final follow-up (t test, P < 0.0001). No eyes developed clinically significant haze, 14.8% developed regression, and 13% had a reduction of 2 or more CDVA lines. Postkeratoplasty topography-guided photorefractive keratectomy has good long-term efficacy and safety, resulting in significant UDVA, refractive, and keratometric improvement. Regression can occur after the first year of treatment, emphasizing the importance of long-term follow-up.

Стандартный кросслинкинг роговичного коллагена в сравнении с одномоментной топографически ориентированной фоторефракционной кератэктомией в сочетании с ускоренным кросслинкингом роговичного коллагена в лечении кератоконуса I-II стадии

Стандартный кросслинкинг роговичного коллагена в сравнении с одномоментной топографически ориентированной фоторефракционной кератэктомией в сочетании с ускоренным кросслинкингом роговичного коллагена в лечении кератоконуса I-II стадии

One-year visual and astigmatic outcomes of keratoconus patients following sequential crosslinking and topography-guided surface ablation: the TOPOLINK study.

To evaluate long-term visual and astigmatic outcomes of sequential corneal crosslinking (CXL) followed by topography-guided photorefractive keratectomy (PRK). Single-practice outpatient setting. Retrospective case review. This is a single-surgeon retrospective case review of eyes with keratoconus undergoing sequential CXL and then topography-guided PRK. Change in uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), topographic, refractive, and keratometric astigmatism was analyzed using power vector analyses at baseline, 6 months, and 12 months after topography-guided PRK. Changes in higher-order aberrations (HOAs), posterior astigmatism, spherical equivalent (SE), and central corneal thickness (CCT) were also analyzed. Correlations between age, time between CXL and PRK, sex, manifest SE, CCT, maximum and average keratometric values, and HOAs were evaluated for significance. Of the 62 eyes studied, regardless of refractive treatment, topography-guided PRK following CXL in patients with keratoconus improved CDVA (mean 20/30; 2-line improvement) and UDVA (mean 20/50; 4-line improvement). Over 12 months, visual acuity continued to improve across all eyes treated (P < .001). Overall, there were significant improvements in corneal astigmatism, maximum keratometry, mean keratometry, SE, posterior astigmatism, and total HOAs. No significant correlations were found between age, sex, time elapsed between CXL and PRK, and age at the time of either procedure on final visual acuity. Results of this study reinforced previous findings that topography-guided PRK in previously cross-linked keratoconus eyes proves to be an efficacious and safe method for improving visual acuity and reducing irregular corneal astigmatism, with continued improvement.

Changes in higher order aberrations after central corneal regularization - a comparative two-year analysis of a semi-automated topography-guided photorefractive keratectomy combined with corneal cross-linking

BackgroundThe optical quality in progressive keratoconus deteriorates due to ectasia and distortion of the corneal shape and optics. While corneal cross-linking (CXL) aims at stopping disease progression, “CXL-Plus” combines CXL with excimer laser ablation to improve visual function. Central Corneal Regularization (CCR) represents a therapeutic excimer laser modality specifically designed to smoothen the ectatic corneal shape and to reduce higher order aberrations (HOA). We set out to compare CXL-Plus, consisting of CXL combined with CCR, with CXL by itself for patients with progressive keratoconus.MethodsRetrospective 2-year matched group analysis of patients who either underwent CXL-Plus (n = 28) or CXL as a sole procedure (n = 28) for progressive keratoconus. Main outcome parameters were HOA, visual function and tomographic results 12 and 24 months postoperatively.ResultsAfter 12 months, the total HOA root mean square wavefront error was reduced from 0.79 ± 0.30 to 0.40 ± 0.19 μm (CXL-Plus; p < 0.0001) and changed from 0.71 ± 0.28 to 0.73 ± 0.36 μm (CXL; p = 0.814). Uncorrected distance visual acuity improved from 0.70 ± 0.35 to 0.36 ± 0.29 logMAR (CXL-Plus; p = 0.0002) and from 0.65 ± 0.39 to 0.46 ± 0.37 logMAR (CXL; p = 0.067), translating to gains of three or more lines in 50% (CXL-Plus) and 36% (CXL) of patients. The steepest keratometry value (Kmax) regressed by 5.84 D (CXL-Plus; p < 0.0001) and 0.66 D (CXL; p = 0.752). For none of the investigated parameters a statistically significant change could be shown between 12 and 24 months.ConclusionsCXL-Plus in the form of a CCR reduces HOA and Kmax more effectively than CXL as a sole procedure.

Visual outcomes of topography-guided photorefractive keratectomy for treatment of patients with irregular cornea

Visual outcomes of topography-guided photorefractive keratectomy for treatment of patients with irregular cornea

Combined corneal CXL and photorefractive keratectomy for treatment of keratoconus: a review

Keratoconus and iatrogenic keratectasia are the corneal ectatic disorders occurring due to biomechanical weakening of the cornea resulting in distorted images, myopia, and irregular astigmatism. Corneal collagen cross-linking (CXL) is performed to arrest keratoconus successfully. The main aim of this review is to discuss the safety and efficacy of the adjuvant therapies, such as the combination of CXL and photorefractive keratectomy (PRK) for the treatment of corneal ectatic disorders. A comprehensive literature search was performed using PubMed, MEDLINE, and Scopus using keywords 'collagen' 'keratoconus', 'keratectasia', 'collagen cross-linking', and 'photorefractive keratectomy'. Search results were restricted to clinical studies published in English. Corneal CXL effectively arrests the progression of keratoconus by enhancing corneal rigidity. However, functional vision is not improved by cross-linking. Combining CXL to refractive surgeries such as topography-guided PRK or transepithelial PRK is found to be a safe and effective method in providing corneal stability as well as significantly improving functional visual acuity with few minor complications. This combined technique also prevents regression of keratoconus and reduce the risk of keratectasia. CXL combined with PRK is a promising therapeutic approach in ophthalmology that can be successfully used to treat progressive keratoconus and other corneal ectatic disorders and to enhance visual acuity.

Simultaneous topography-guided photorefractive keratectomy with accelerated collagen cross-linking in the treatment of stage I keratoconus

Purpose: to evaluate the efficiency of simultaneous topography-guided photorefractive keratectomy (PRK) with accelerated collagen cross-linking in the treatment of stage I keratoconus.Material and methods. 38 patients (49 eyes) aged 18 to 44 with stage I keratoconus were treated with simultaneous topography-guided PRK combined with accelerated corneal collagen crosslinking. Along with standard ophthalmological testing, patients underwent aberrometry, confocal microscopy, optical coherence tomography of the cornea, imaging of the anterior eye section on a Scheimpflug analyzer, and examination of the biomechanical properties of the cornea. The follow-up period was 2 years.Results. Two years after surgery, uncorrected visual acuity which originally was 0.23 ± 0.03 showed a statistically significant increase and reached 0.72 ± 0.02; best corrected visual acuity improved from 0.44 ± 0.03 to 0.89 ± 0.02; the refractive power of the cornea fell from 45.03 ± 0.28 to 42.55 ± 0.31 D; the spherical component of refraction reduced from -2.00 ± 0.19 to -0.73 ± 0.09 D; the cylinder component reduced from 2.46 ± 0.14 to 0.79 ± 0.07 mm, the thinnest point of the cornea reduced from 486.30 ± 4.78 to 406.80 ± 6.51 μm. The highest order aberrations showed the following results: Coma index reduced from 0.27 ± 0.12 to 0.08 ± 0.07, Tilt reduced from 0.53 ± 0.11 to 0.10 ± 0,09, and Trefoil reduced from 0.13 ± 0.04 to 0.05 ± 0.02.Conclusion. The analysis of clinical and functional results, biomechanical properties and structures of the cornea confirmed the efficacy and safety of the combined treatment of patients with stage I keratoconus.

The impact of keratoconus treatment with the Athens Protocol (partial topography-guided photorefractive keratectomy combined with higher-fluence corneal collagen cross-linking) on quality of life: a long-term study.

PurposeThe aim of this study was to evaluate the health-related quality of life (HRQoL) before and after the management of keratoconus (KCN) with Combined Topography-Guided Transepithelial partial photorefractive keratectomy (PRK) and corneal Cross-Linking: the Athens Protocol.Patients and methodsThirty-four consecutive patients treated for progressive KCN were selected for retrospective telephone interview and individual questionnaire submission. A disease-specific HRQoL questionnaire was administered before and after the Athens Protocol intervention, using the following administrative questionnaires: National Eye Institute Visual Function Questionnaire (NEI VFQ) 25/39 and IVI-28. The disease grade was ranked according to the Amsler–Krumeich classification (KCN severity). Reliability of collected data was evaluated with Cronbach’s α test.ResultsPatients’ age ranged from 15 to 51 years at the time of the operation. Mean time before the operation during which the questionnaires were administered was 52±6 months. General visual acuity, psychological well-being, and driving ability showed significant improvement. Younger keratoconic patients tend to have more enhanced psychological status and to cope better with difficulties in everyday activities (prior to operation) than older patients.ConclusionThe Athens Protocol treatment has been proven to be beneficial to patients in a large number of aspects.

Management of progressive keratoconus with partial topography-guided PRK combined with refractive, customized CXL - a novel technique: the enhanced Athens protocol.

PurposeTo report a novel application of partial topography-guided photorefractive keratectomy combined with topographically customized, higher fluence, and variable pattern corneal cross-linking applied on the same day of the treatment of keratoconus.MethodsA topography-guided partial photorefractive keratectomy treatment of maximum 30 µm over the thinnest cone area was applied initially followed by a 7 mm, 50 µm phototherapeutic keratectomy treatment to address epithelial removal. 0.02% Mitomycin C was applied for 20 seconds and then the exposed stroma was soaked with 0.1% riboflavin solution for 5 minutes. The cornea was then treated with a customized, variable-pattern and 20 mW/cm2 fluence for a total of 5–10 J, and up to 15 J of energy was delivered with the KXL-II device employing an active tracker. The center of the pattern that received the 15 J was topography-matched with the thinnest area of the cone. Visual acuity, refractive error, cornea clarity, keratometry, topography, pachymetry with a multitude of modalities and endothelial cell density were evaluated over 36 months.ResultsKeratoconus was stabilized in all cases. The severity of keratoconus stage by Amsler– Krumeich criteria improved from an average of 3.2 (1–4) to 1.8 (0–3). Uncorrected distance visual acuity changed from preoperative 20/80 to 20/25 at 6 months. A maximum astigmatic reduction of 7.8 D (5.3–15.6), and a significant cornea surface normalization (an index of height decentration improvement from 0.155 [±0.065] to 0.045 [±0.042]) were achieved by 1 month and remained relatively stable for 36 months postoperatively. Two cases delayed full reepithelialization for up to 9 days.ConclusionThis paper introduces a novel technique in order to maximize the refractive normalization effect along with ectasia stabilization in young keratoconus patients. This may facilitate the use of less tissue ablation, in comparison to utilizing a homogeneous UV light beam for corneal cross-linking in Athens Protocol cases. It broadens the number of potential candidate cases that would have been limited to employ this technique due to tissue thickness limitations.

Topography-guided photo-refractive keratectomy followed by corneal collagen cross-linking for keratoconus

Background: KC is a bilateral, progressive, non-inflammatory corneal degeneration. Corneal deformation and thinning causes irregular astigmatism and leads to visual impairment. Aim of the work: this study aimed to evaluate simultaneous topography-guided partial PRK and CXL as a therapeutic intervention in patients with KC. Methodology: the present study was designed to evaluate simultaneous topography-guided partial PRK and CXL as a therapeutic intervention in patients with KC. It included 25 keratoconic eyes of 17 patients; 8 cases were bilateral and 9 cases were unilateral. All included cases underwent full history taking and ophthalmologic examinations for preoperative evaluation and postoperative assessment. Follow up was carried out at first postoperative day and at 1, 3 and 6 months post-operatively. Results: when comparing K1, K2, thinnest location and BCVA at 1, 3 and 6 months postoperatively to the corresponding values at first postoperative day, there was non-significant difference at any point of time. Conclusion: simultaneous topography-guided partial PRK and CXL as a therapeutic intervention in patients with keratoconus is an effective without significant complications; thus, it had a good efficacy, stability over time and safety.

Topography-guided photo-refractive keratectomy followed by corneal collagen cross-linking for keratoconus

Background: KC is a bilateral, progressive, non-inflammatory corneal degeneration. Corneal deformation and thinning causes irregular astigmatism and leads to visual impairment. Aim of the work: this study aimed to evaluate simultaneous topography-guided partial PRK and CXL as a therapeutic intervention in patients with KC. Methodology: the present study was designed to evaluate simultaneous topography-guided partial PRK and CXL as a therapeutic intervention in patients with KC. It included 25 keratoconic eyes of 17 patients; 8 cases were bilateral and 9 cases were unilateral. All included cases underwent full history taking and ophthalmologic examinations for preoperative evaluation and postoperative assessment. Follow up was carried out at first postoperative day and at 1, 3 and 6 months post-operatively. Results: when comparing K1, K2, thinnest location and BCVA at 1, 3 and 6 months postoperatively to the corresponding values at first postoperative day, there was non-significant difference at any point of time. Conclusion: simultaneous topography-guided partial PRK and CXL as a therapeutic intervention in patients with keratoconus is an effective without significant complications; thus, it had a good efficacy, stability over time and safety.