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Corneal tissue addition keratoplasty is a novel surgical procedure utilizing preserved allogenic femtosecond laser–shaped corneal tissue inlays to improve corneal topography and vision in patients with keratoconus and ectasia. Purpose: To report results of Corneal Tissue Addition Keratoplasty (CTAK) for keratoconus (KC) and ectasia after laser in situ keratomileusis. Setting: Cornea and refractive surgery practice. Design: Single center, prospective, open label clinical trial. Methods: 21 eyes of 18 patients underwent CTAK. A tissue inlay of preserved corneal tissue was cut to customized specifications with a femtosecond laser and placed in a laser-created channel in the host cornea. Postoperative uncorrected and corrected distance visual acuity (UDVA, CDVA), manifest refraction spherical equivalent (MRSE), topographic mean keratometry (Kmean), maximum keratometry (Kmax), and the point of maximum flattening (Kmaxflat) were measured. Results: Average UDVA improved from 1.21 ± 0.35 logMAR lines (LL) (20/327) to 0.61 ± 0.25 LL (20/82) (P <.001). Average CDVA improved from 0.62 ± 0.33 LL (20/82) to 0.34 ± 0.21 LL (20/43) (P =.002), and average MRSE improved from −6.25 ± 5.45 diopters (D) to −1.61 ± 3.33 D (P =.002). Individually, 20 eyes (95.2%) gained more than 2 lines of UDVA, with 10 eyes (47.6%) gaining more than 6 lines, and no eyes worsening. 12 eyes (57.1%) gained at least 2 lines of CDVA, with 1 eye worsening by more than 2 lines. At 6 months, average Kmean flattened by −8.44 D (P =.002), Kmax flattened by −6.91 D (P =.096), and mean Kmaxflat was −16.03 D. Conclusions: CTAK is a promising procedure to improve visual acuity and topography in patients with KC and ectasia. [ABSTRACT FROM AUTHOR]

Purpose: To assess anterior corneal higher-order aberrations (HOAs) after corneal crosslinking (CXL) and intrastromal corneal ring segments (Intacs) used adjunctively. Setting: Cornea and refractive surgery practice. Design: Prospective, randomized clinical trial. Methods: One hundred fifty-eight eyes of 150 patients were randomized into 2 groups: concurrent, Intacs and CXL during the same session (n = 81), or sequential, Intacs followed by CXL 3 months later (n = 77). Outcomes included changes in total, coma, trefoil, and spherical anterior corneal HOA 6 months after Intacs/CXL. The change in anterior corneal HOAs was correlated with the change in uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and topography indices of maximum keratometry (Kmax), maximum flattening keratometry (Kmaxflat), and inferior-superior (I-S) ratio. A subjective visual function questionnaire was also analyzed. Results: UDVA, CDVA, Kmax, I-S, and Kmaxflat all improved 6 months after treatment (UDVA = -0.22 +/- 0.34, P <.001; CDVA = -0.13 +/- 0.24, P <.001; Kmax = -3.1 +/- 3.0D, P <.001; I-S = -4.2 +/- 5.0 diopters [D], P <.001; Kmaxflat = -7.9 +/- 4.0 D, P <.001). Total anterior corneal HOA, vertical coma, and horizontal coma anterior corneal HOAs significantly improved by -1.05 +/- 0.93 [mu]m (P <.001), -1.53 +/- 1.18 [mu]m (P <.001), and -0.35 +/- 0.57 [mu]m (P <.001), respectively. Spherical anterior corneal HOAs increased by 0.24 +/- 0.70 [mu]m (P <.001) at 6 months after Intacs/CXL. The change in trefoil was not statistically significant (P trefoil0 =.06, P trefoil30 =.2). There were no significant differences between the changes in anterior corneal HOAs in the sequential and same-day Intacs/CXL groups. The change in total anterior corneal HOAs was correlated with Kmax, Kmaxflat, and the I-S ratio. There was no correlation between the change in anterior corneal HOAs and the change in visual acuity or visual function survey responses. Conclusions: Total, horizontal coma, and vertical coma anterior corneal HOAs improved after Intacs/CXL. Spherical anterior corneal HOAs increased postoperatively, and there was no change in trefoil. Improvement of anterior corneal HOAs did not correlate with visual acuity improvement or subjective visual satisfaction outcomes. [ABSTRACT FROM AUTHOR]

Purpose: To determine preoperative patient characteristics that may predict topography and visual acuity outcomes of corneal collagen crosslinking (CXL). Setting: Cornea and refractive surgery practice. Design: Cohort study. Methods: Crosslinking was performed in eyes with keratoconus or corneal ectasia. Multiple regression and odds ratio analyses were performed to determine independent predictors of changes in topography-derived maximum keratometry (K) and corrected distance visual acuity (CDVA) 1 year postoperatively. Preoperative characteristics included sex, age, uncorrected distance visual acuity (UDVA), CDVA, maximum keratometry (K), corneal thickness, corneal haze, disease group, and cone location. Postoperative improvement in maximum K was defined as flattening of 2.0 diopters (D) or more and worsening as steepening of 1.0 D or more. Improvement in CDVA was defined as a gain of 2 lines or more and worsening as a loss of 1 line or more. Results: The study comprised 104 eyes (66 keratoconus; 38 corneal ectasia). Eyes with a preoperative CDVA of 20/40 or worse were 5.9 times (95% confidence interval [CI], 2.2-6.4) more likely to improve 2 Snellen lines or more. Eyes with a maximum K of 55.0 D or more were 5.4 times (95% CI, 2.1-14.0) more likely to have topographic flattening of 2.0 D or more. No preoperative characteristics significantly predicted worsening of visual acuity or corneal topography. Conclusions: Patients with worse preoperative CDVA and higher K values, particularly with a CDVA of 20/40 or worse or a maximum K of 55.0 D or more, were most likely to have improvement after CXL. No preoperative characteristics were predictive of CXL failure. Financial Disclosure: Dr. Hersh is a medical monitor for Avedro, Inc. Dr. Greenstein has no financial or proprietary interest in any material or method mentioned. [Copyright &y& Elsevier]

Purpose: To assess subjective visual function after corneal collagen crosslinking (CXL). Setting: Cornea and refractive surgery subspecialty practice. Design: Prospective randomized controlled clinical trial. Methods: Patients completed a subjective questionnaire regarding visual symptoms administered preoperatively and 1 year after CXL. Patients ranked self-reported symptoms of photophobia, difficulty night driving, difficulty reading, diplopia, fluctuations in vision, glare, halo, starburst, dryness, pain, and foreign-body sensation on a scale from 1 to 5. Possible associations of symptoms with changes in corrected distance visual acuity (CDVA) and maximum keratometry were also analyzed. Results: One hundred seven eyes of 76 patients had CXL for keratoconus (n = 71) or ectasia (n = 36). The mean preoperative to 1-year postoperative changes in night driving (3.2 ± 1.5 [SD] to 2.8 ± 1.5), difficulty reading (3.1 ± 1.5 to 2.9 ± 1.3), diplopia (2.5 ± 1.3 to 2.1 ± 1.2), glare (3.1 ± 1.4 to 2.7 ± 1.2), halo (2.9 ± 1.4 to 2.5 ± 1.3), starbursts (2.6 ± 1.5 to 2.4 ± 1.4), and foreign-body sensation (1.8 ± 1.1 to 1.6 ± 0.9) were statistically significant. There were no associations between the change in any symptom and changes in CDVA. There was a weak association between the change in night driving, pain, and foreign-body sensations and the change in maximum keratometry. Conclusions: After CXL, patients noted subjective improvement in visual symptoms, specifically night driving, difficulty reading, diplopia, glare, halo, starbursts, and foreign-body sensation. These subjective outcomes corroborate quantitative clinical improvements seen after CXL. Financial Disclosure: Dr. Hersh is medical monitor for Avedro, Inc. No author has a financial or proprietary interest in any material or method mentioned. [ABSTRACT FROM AUTHOR]

Purpose: To determine changes in higher-order aberrations (HOAs) after corneal collagen crosslinking (CXL). Setting: Cornea and refractive surgery practice. Design: Prospective randomized controlled clinical trial. Methods: Corneal and ocular HOAs were measured and analyzed using the Pentacam device and Ladarwave aberrometer, respectively, at baseline and 12 months after CXL. Results: Ninety-six eyes (64 keratoconus, 32 ectasia) of 73 patients had CXL. A fellow-eye control group comprised 42 eyes. The mean preoperative total anterior corneal HOAs, total coma, 3rd-order coma, and vertical coma were 4.68 μm ± 2.33 (SD), 4.40 ± 2.32 μm, 4.36 ± 2.30 μm, and 4.04 ± 2.27 μm, respectively. At 1 year, the mean values decreased significantly to 4.27 ± 2.25 μm, 4.01 ± 2.29 μm, 3.96 ± 2.27 μm, and 3.66 ± 2.22 μm, respectively (all P<.001). There were no significant changes in posterior corneal HOAs. The mean preoperative total ocular HOAs, total coma, 3rd-order coma, trefoil, and spherical aberration were 2.80 ± 1.0 μm, 2.60 ± 1.03 μm, 2.57 ± 1.03 μm, 0.98 ± 0.46 μm, and 0.90 ± 0.42 μm, respectively. At 1 year, the mean values decreased significantly to 2.59 ± 1.06 μm, 2.42 ± 1.07 μm, 2.39 ± 1.07 μm, 0.88 ± 0.49 μm, and 0.83 ± 0.38 μm, respectively (all P=.01). After CXL, HOAs were significantly improved compared with the control group. Changes in HOAs were not statistically associated with an improvement in visual acuity or most subjective visual symptoms, however. Conclusion: Corneal and ocular HOAs decreased after CXL, suggesting an improvement in corneal shape. Financial Disclosure: Dr. Hersh is medical monitor for Avedro, Inc. No author has a financial or proprietary interest in any material or method mentioned. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate changes in corneal topography indices after corneal collagen crosslinking (CXL) in patients with keratoconus and corneal ectasia and analyze associations of these changes with visual acuity. Setting: Cornea and refractive surgery subspecialty practice. Design: Prospective randomized controlled clinical trial. Methods: Corneal collagen crosslinking was performed in eyes with keratoconus or ectasia. Quantitative descriptors of corneal topography were measured with the Pentacam topographer and included 7 indices: index of surface variance, index of vertical asymmetry, keratoconus index, central keratoconus index, minimum radius of curvature, index of height asymmetry, and index of height decentration. Follow-up was 1 year. Results: The study comprised 71 eyes, 49 with keratoconus and 22 with post-LASIK ectasia. In the entire patient cohort, there were significant improvements in the index of surface variance, index of vertical asymmetry, keratoconus index, and minimum radius of curvature at 1 year compared with baseline (all P<.001). There were no significant differences between the keratoconus and ectasia subgroups. Improvements in postoperative indices were not correlated with changes in corrected or uncorrected distance visual acuity. Conclusions: There were improvements in 4 of 7 topography indices 1 year after CXL, suggesting an overall improvement in corneal shape. However, no significant correlation was found between the changes in individual topography indices and changes in visual acuity after CXL. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. Additional disclosure is found in the footnotes. [ABSTRACT FROM AUTHOR]

Purpose: To determine the changes in corneal thickness over time after corneal collagen crosslinking (CXL) for keratoconus and corneal ectasia. Setting: Cornea and refractive surgery subspecialty practice. Design: Prospective randomized controlled clinical trial. Methods: Corneal thickness at the apex, thinnest point, and pupil center were measured using Scheimpflug imaging (Pentacam) at baseline and 1, 3, 6, and 12 months after CXL. The treatment group was compared with both a sham-procedure control group and a fellow-eye control group. Associations with clinical outcomes (uncorrected and corrected distance visual acuities and maximum keratometry) were analyzed. Results: The study comprised 82 eyes, 54 with keratoconus and 28 with ectasia after laser in situ keratomileusis. The mean preoperative thinnest pachymetry was 440.7 μm ± 52.9 (SD). After CXL, the cornea thinned at 1 month (mean change −23.8 ± 28.7 μm; P<.001) and from 1 to 3 months (mean change −7.2 ± 20.1 μm, P=.002), followed by a recovery of the corneal thickness between 3 months and 6 months (mean +20.5 ± 20.4 μm; P<.001). At 1 year, apex and pupil-center thicknesses returned to baseline (P=.11 and P=.06, respectively); however, the thinnest pachymetry remained slightly decreased from baseline to 12 months (mean change −6.6 ± 22.4 μm; P=.01). The recovery of corneal thickness was more rapid in ectasia than in keratoconus. There was no association between the degree of corneal thinning at 3 months and clinical outcomes after CXL. Conclusions: After CXL, the cornea thins and then recovers toward baseline thickness. The cause and implications of corneal thickness changes after CXL remain to be elucidated. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. Additional disclosure is found in the footnotes. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate 1-year outcomes of corneal collagen crosslinking (CXL) for treatment of keratoconus and corneal ectasia. Setting: Cornea and refractive surgery subspecialty practice. Design: Prospective randomized controlled clinical trial. Methods: Collagen crosslinking was performed in eyes with keratoconus or ectasia. The treatment group received standard CXL and the sham control group received riboflavin alone. Principal outcomes included uncorrected (UDVA) and corrected (CDVA) distance visual acuities, refraction, astigmatism, and topography-derived outcomes of maximum and average keratometry (K) value. Results: The UDVA improved significantly from 0.84 logMAR ± 0.34 (SD) (20/137) to 0.77 ± 0.37 logMAR (20/117) (P = .04) and the CDVA, from 0.35 ± 0.24 logMAR (20/45) to 0.23 ± 0.21 logMAR (20/34) (P<.001). Fifteen patients (21.1%) gained and 1 patient lost (1.4%) 2 or more Snellen lines of CDVA. The maximum K value decreased from baseline by 1.7 ± 3.9 diopters (D) (P<.001), 2.0 ± 4.4 D (P = .002), and 1.0 ± 2.5 D (P = .08) in the entire cohort, keratoconus subgroup, and ectasia subgroup, respectively. The maximum K value decreased by 2.0 D or more in 22 patients (31.0%) and increased by 2.0 D or more in 3 patients (4.2%). Conclusions: Collagen crosslinking was effective in improving UDVA, CDVA, the maximum K value, and the average K value. Keratoconus patients had more improvement in topographic measurements than patients with ectasia. Both CDVA and maximum K value worsened between baseline and 1 month, followed by improvement between 1, 3, and 6 months and stabilization thereafter. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. Additional disclosure is found in the footnotes. [Copyright &y& Elsevier]

Purpose: To determine the natural history of collagen crosslinking (CXL)–associated corneal haze measured by Scheimpflug imagery and slitlamp biomicroscopy in patients with keratoconus or ectasia after laser in situ keratomileusis. Setting: Cornea and refractive surgery subpecialty practice, United States. Design: Prospective randomized controlled clinical trial. Methods: The treatment group received ultraviolet-A/riboflavin CXL therapy. The control group received riboflavin alone without epithelial debridement. To objectively measure CXL-associated corneal haze, corneal densitometry using Scheimpflug imagery was measured and the changes in haze were analyzed over time. A similar analysis was performed using clinician-determined slitlamp haze. Correlation of CXL-associated corneal haze with postoperative outcomes was analyzed. Results: The mean preoperative corneal densitometry was 14.9 ± 1.93 (SD) (Pentacam Scheimpflug densitometry units). Densitometry peaked at 1 month (mean 23.4 ± 4.40; P<.001), with little change at 3 months (mean 22.4 ± 4.79; P = .06) and decreased between 3 months and 6 months (19.4 ± 4.48; P<.001) and between 6 months and 12 months. By 12 months, densitometry had not completely returned to baseline in the entire cohort (mean 17.0 ± 3.82; P<.001) and the keratoconus subgroup; however, it returned to baseline in the ectasia group (16.1 ± 2.41; P = .15). The postoperative course of slitlamp haze was similar to objective densitometry measurements. Increased haze, measured by densitometry, did not correlate with postoperative clinical outcomes. Conclusions: The time course of corneal haze after CXL was objectively quantified; it was greatest at 1 month, plateaued at 3 months, and was significantly decreased between 3 months and 12 months. Changes in haze did not correlate with postoperative clinical outcomes. Financial Disclosure: Drs. Greenstein and Fry and Ms. Bhatt have no financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes. [Copyright &y& Elsevier]

Purpose: Keratoconus is a progressive disease characterized by changes in corneal shape, resulting in loss of visual function. There remains a lack of comprehensive understanding regarding its underlying pathophysiology. This review aims to bridge this gap by exploring structural failures and inflammatory processes involved in the etiology and progression of keratoconus., Methods: A literature review was conducted using PubMed and Google Scholar databases, screening for articles published in English using the keyword combinations of "keratoconus" with "pathophysiology," "pathology," "metabolism," "inflammatory," "oxidative stress," "cytokines," "enzymes," "collagen," and "cornea." Articles published between January 1, 1970, and June 1, 2023, were queried and reviewed, with greater emphasis placed on more recent data. Fifty-six relevant studies were examined to develop a thorough review of the pathophysiological mechanisms at play in keratoconus., Results: Biomechanical structural failures in the cornea seem to be the primary militating factors in keratoconus etiology and progression. These include disruptions in the arrangement in the collagen lamellae, a decrease in collagen levels, a decrease in natural collagen crosslinking, and changes in lysosomal enzyme activity. Immunologic changes have also been identified in keratoconus, challenging the traditional view of the condition as noninflammatory. Elevated levels of proinflammatory cytokines like IL-1b, IL-6, IL-17, and TNF-α have been observed, along with increased apoptosis of keratocytes. Increased oxidative stress leads to the activation of collagenase and gelatinase enzymes., Conclusions: Keratoconus is a complex condition influenced by both structural defects and inflammatory processes. Understanding these mechanisms can inform clinical management and potentially lead to more effective treatments., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Abstract: In this report, we discuss contact lens (CL) fitting in a patient with a history of keratoconus (KC), before and after undergoing topography-guided photorefractive keratectomy (TG PRK). Before TG PRK, the patient failed multiple CL modalities and reported difficulty with his habitual CLs and inadequate spectacle-corrected visual acuity to perform his activities of daily living. In this case, a collaborative, comprehensive approach to visual management in a patient with KC was used, and after TG PRK was performed to improve his corneal contour and symmetry, our patient was fit with a standard soft CL and additionally had improved spectacle-corrected visual acuity., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2023 Contact Lens Association of Ophthalmologists.)

Purpose: To quantitate corneal haze and analyze the postoperative time course of corneal haze after transepithelial corneal collagen cross-linking (TECXL) in patients with keratoconus., Methods: Patients underwent TECXL and were randomized into 2 groups. One group received intraoperative riboflavin 0.10% every minute, and the second group received riboflavin 0.10% every 2 minutes during ultraviolet exposure. Scheimpflug densitometry was measured preoperatively, and at 1, 3, 6, and 12 months to assess the postoperative time course. Densitometry measurements were also correlated with visual acuity, pachymetry, and topography outcomes., Results: Fifty-nine eyes of 43 patients with keratoconus were analyzed. Preoperative mean corneal densitometry was 20.45 ± 2.79. Mean densitometry increased at 1 month (22.58 ± 3.79; P < 0.001), did not significantly change between 1 and 3 months (22.64 ± 3.83; P = 0.8), and significantly improved between 3 and 12 months postoperatively (mean6 21.59 ± 3.39; P = 0.002, mean12 20.80 ± 3.27; P = 0.002). There was no difference between preoperative and 1-year densitometry measurements (P = 0.21). There was no significant difference between the 1-minute and 2-minute subgroups. In addition, corneal densitometry at either 3 months or 1 year did not correlate with uncorrected distance visual acuity (P = 0.4), corrected distance visual acuity (P = 0.1), or maximum keratometry (P = 0.5), 1 year after corneal collagen cross-linking (CXL)., Conclusions: After TECXL, corneal haze increased slightly at 1 month, plateaued between 1 and 3 months, and returned to baseline between 3 and 12 months. In general, corneal haze in this study was substantially less than the haze previously reported for the standard cross-linking procedure. CXL-associated corneal haze did not correlate with the postoperative visual or topographic outcomes 1 year after CXL.