Evaluation of Changes in Visual Acuity, Contrast Sensitivity and Aberrations in Patients with Keratoconus after Corneal Collagen Cross-linking.
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SUBMITTER: Zarei-Ghanavati S
PROVIDER: S-EPMC5525493 | biostudies-other | 2017 Jul-Sep
REPOSITORIES: biostudies-other
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Project description:To evaluate the efficacy of collagen cross-linking (CXL) one year after treatment for keratoconus compared to no treatment by summarizing randomized controlled trials (RCTs) using a systematic review.Trials meeting the selection criteria were quality appraised, and the data were extracted by two independent authors. The outcome parameters included maximum keratometry (Kmax), corneal thickness at the thinnest point, best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), spherical equivalent (SE) refraction, and cylindrical refraction one year after CXL. We compared the changes in the above parameters with the control group.We identified five RCTs involving 289 eyes that met the eligibility criteria for this systematic review. The changes in BSCVA from baseline to one year exhibited a significant difference between the two groups. There was no statistically significant difference between the two groups for changes in corneal thickness and cylindrical refraction. We did not conduct a meta-analysis in Kmax, UCVA, and SE refraction because their I2 values were greater than 50%.According to the systematic review, CXL may be effective in halting the progression of keratoconus for one year under certain conditions, although evidence is limited due to the significant heterogeneity and paucity of RCTs.
| S-EPMC5485290 | biostudies-other
Project description:PurposeTo investigate patient risk factors and to look for potential causes of sterile infiltrates following an unexpected cluster of sterile keratitis after a routine collagen cross-linking (CXL) list.MethodsThe records of all 148 cases of CXL were reviewed retrospectively. The equipment and solutions used and our clinic's standard operating procedure for CXL were reviewed. An in-vitro experiment to explore the variation in ultraviolet A (UVA) irradiance from fluctuations in the working distance of the UVA lamp was conducted.ResultsThe four patients who developed sterile infiltrates had steeper maximum corneal curvatures (68.0±7.3?D) and thinner pachymetry (389.9±49.0??m) than the 144 who did not (57.0±8.2?D, P=0.05; 454.6±45.4??m, P=0.08). A corneal curvature of >60?Dand a pachymetry of <425??m were significant risk factors. All four affected cases obtained a complete resolution with topical antibiotics and steroids. The unaided VA and the maximum K improved from their pre-operative levels in three out of four patients. A 2-mm reduction in distance of the VEGA C.B.M. X-Linker from a treated surface increased irradiance to 3.5-3.7?mW/cm(2), which is above the threshold for endothelial toxicity.ConclusionPatients with thinner and steeper corneas are at an increased risk of developing sterile keratitis. The visual outcomes despite this complication are good.
| S-EPMC4274277 | biostudies-literature
Project description:IntroductionEpithelium-off cross-linking (epi-off CXL) has long been established as the gold standard treatment for progressive keratoconus. Several protocols for epithelium-on (epi-on) CXL have been proposed to help reduce post-operative pain and facilitate visual recovery, but there is no epi-on treatment approach that is currently approved in the United States. The hydrophilic and macromolecular characteristics of conventional epi-off riboflavin formulations may create clinical challenges for absorption through an intact epithelium. This study investigates the clinical efficacy of a dextran-free hypotonic riboflavin ophthalmic solution (Photrexa, Glaukos, Burlington, MA, USA), approved for epi-off CXL, in a novel epi-on CXL protocol.MethodsTwenty-five eyes of 17 patients were treated in this prospective, single-arm study using a hypotonic riboflavin formulation without dextran and low irradiance UVA (3mW/cm2) for epi-on CXL. Visual acuity, as well as refractive and keratometry outcomes, were observed over 12 months.ResultsAt 12 months, Kmax was stable with no clinically or statistically significant change from a mean pre-op of 55.4D to 55.9D (p=0.13). Uncorrected and best corrected logMAR visual acuity significantly improved from 0.77 to 0.62 and from 0.17 to 0.12, respectively. There were no significant adverse safety events.ConclusionPatients who underwent epi-on CXL with dextran-free hypotonic riboflavin demonstrated improvements in uncorrected and best corrected visual acuity with stable keratometry at 12 months post-operatively. The efficacy is consistent with other epi-on studies to date but remains lower than standard epi-off CXL. New technologies, including supplemental oxygen and transepithelial riboflavin ophthalmic solutions, are currently under clinical evaluation and may offer a path forward for epi-on CXL in the USA.
| S-EPMC8273905 | biostudies-literature
Project description:To investigate the effects of combined corneal wavefront-guided transepithelial photorefractive keratectomy (tPRK) and accelerated corneal collagen cross-linking (CXL) after intracorneal ring segment (ICRS) implantation in patients with moderate keratoconus.Medical records of 23 eyes of 23 patients undergoing combined tPRK and CXL after ICRS implantation were retrospectively analyzed. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), corneal indices based on Scheimpflug tomography, higher-order aberrations (HOAs), and corneal biomechanical properties were evaluated before and after ICRS implantation, and at 1, 3, and 6 months after combined tPRK and CXL.There were significant improvements in final logMAR UDVA and logMAR CDVA, and reductions in sphere, MRSE, and all corneal indices from baseline. Significant improvements in logMAR UDVA and reductions in sphere, MRSE, maximal keratometry, keratometry at the apex, mean keratometry, and keratoconus index were noted after ICRS implantation. After tPRK and CXL, significant improvements in logMAR UDVA and logMAR CDVA, and reductions in cylinder and all corneal indices were observed. There were significant improvements in final root mean square HOAs and coma aberrations from baseline, but no changes from baseline after ICRS implantation. Significant reductions in final radius and deformation amplitude from baseline were noted.Combined tPRK and accelerated CXL after ICRS implantation in moderate keratoconus appears to be a safe and effective treatment, providing an improvement in visual acuity, corneal indices, and HOAs.retrospectively registered (identification no. NCT03355430 ). Date registered: 28/11/2017.
| S-EPMC5746954 | biostudies-literature
Project description:PurposeTo present the case of a patient that underwent corneal crosslinking for progressive keratoconus and 18 months later revealed clinically significant corneal stromal haze.ObservationsA 20-year-old male presented with progressive visual loss OU for the past few years. His corrected distance visual acuity (CDVA) OD was 20/30 (-2.75 -1.75 @55) and OS 20/30 (-0.50 -1.75@110). Corneal topography revealed keratoconus OU and the patient underwent corneal crosslinking according to the Dresden Protocol. The postoperative regimen included combined tobramycin and dexamethasone qid along with lubrication until epithelium healed and then fluorometholone qid with weekly tapering. At 3 months postoperatively, his topography was stable and his corrected distance visual acuity (CDVA) was 20/25 OU. On slit lamp examination, only clinically insignificant stromal haze was observed. At 18 months postoperatively, the patient reported vision deterioration. On examination his CDVA was 20/25 in right eye, and 20/40 in his left eye. Deep stromal haze was revealed in his central cornea, more dense in his left eye. Corneal topography was stable and the CDVA loss was attributed to the notable deep stromal haze. The patient was treated with dexamethasone qid with biweekly tapering. 18 months after corneal crosslinking, the patient demonstrated clinically significant stromal haze, most prominent OS. He was treated with dexamethasone qid. One month later his CDVA OS gradually improved to 20/25, and stromal haze was still noted but less dense.Conclusions and importanceLate-onset deep corneal haze is a possible complication of corneal crosslinking in keratoconic patients.
| S-EPMC6411486 | biostudies-literature
Project description:Purpose:The purpose of this study was to compare the effects of transepithelial crosslinking (trans-CXL) versus epithelium-off crosslinking (epi-off CXL) for progressive keratoconus with respect to the development of higher order aberrations (HOAs) and their effects on visual acuity. Materials and methods:A total of 61 patients were randomized and examined preoperatively and 1, 3, 6, and 12 months postoperatively in an academic referral center. Total corneal HOAs were compared between the two treatment groups using mixed linear modeling. Types of HOAs (coma, trefoil, and spherical aberration) that differed between groups were entered in a multivariable analysis to test their effect on uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA). Results:The epi-off CXL group had more flattening in maximal keratometry compared to the trans-CXL group (P=0.02). UDVA did not differ significantly between the groups (P=0.59); however, CDVA was significantly more improved in the trans-CXL group (P=0.02). Horizontal trefoil improved more in the epi-off group compared to the trans-CXL group (P=0.04), whereas the other HOAs were virtually unchanged in both groups. Differences in changes in HOAs between the two groups had no effect on either UCVA (P=0.76) or CDVA (P=0.96). Conclusion:Although HOAs are clinically relevant determinants of vision quality in keratoconus patients, the change in total HOAs post treatment did not differ between the trans-CXL and epi-off CXL groups. Only horizontal trefoil differed significantly post treatment between the trans-CXL and epi-off CXL groups. However, this difference did not independently affect either UDVA or CDVA. Trans-CXL provides no benefit over epi-off CXL regarding visual relevant HOAs.
| S-EPMC5669787 | biostudies-literature
Project description:BackgroundThe aim of this study was to evaluate the visual acuity of adult zebrafish by assessing the optokinetic reflex. Using a modified commercially available optomotor device (OptoMotry®), virtual three-dimensional gratings of variable spatial frequency or contrast were presented to adult zebrafish. In a first experiment, visual acuity was evaluated by changing the spatial frequency at different angular velocities. Thereafter, contrast sensitivity was evaluated by changing the contrast level at different spatial frequencies.ResultsAt the different tested angular velocities (10, 15, 20, 25, and 30 d/s) and a contrast of 100%, visual acuity values ranged from 0.56 to 0.58 c/d. Contrast sensitivity measured at different spatial frequencies (0.011, 0.025, 0.5, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.55 c/d) with an angular velocity of 10 d/s and 25 d/s revealed an inverted U-shaped contrast sensitivity curve. The highest mean contrast sensitivity (±SD) values of 20.49 ± 4.13 and 25.24 ± 8.89 were found for a spatial frequency of 0.05 c/d (angular velocity 10 d/s) and 0.1 c/d (angular velocity 25 d/s), respectively.ConclusionsVisual acuity and contrast sensitivity measurements in adult zebrafish with the OptoMotry® device are feasible and reveal a remarkably higher VA compared to larval zebrafish and mice.
| S-EPMC3453526 | biostudies-literature
Project description:ObjectiveTo evaluate the efficacy of corneal collagen cross-linking (CXL) for the treatment of keratoconus.MethodsWe performed a literature search for randomized controlled trials that assessed the effect of CXL in slowing progression of keratoconus. The primary outcome measures included changes of topographic parameters, visual acuity, and refraction. Efficacy estimates were evaluated by weighted mean difference (WMD) and 95% confidence interval (CI) for absolute changes of the interested outcomes.ResultsSignificant decrease in mean keratometry value, maximum keratometry value and minimum keratometry value were demonstrated in the CXL group compared with the control group (WMD = -1.65; 95% CI: -2.51 to -0.80; P < 0.00001; WMD = -2.05; 95% CI: -3.10 to -1.00; P < 0.00001; WMD = -1.94; 95% CI: -2.63 to -1.26; P < 0.00001; respectively). Best spectacle-corrected visual acuity improved significantly in CXL group (WMD = -0.10; 95% CI: -0.15 to -0.05; P < 0.00001), whereas uncorrected visual acuity did not differ statistically. Manifest cylinder error decreased significantly in patients undergoing CXL procedure compared with control patients in sensitivity analysis (WMD = -0.388; 95% CI: -0.757 to -0. 019; P = 0.04). The changes in central corneal thickness and intraocular pressure were not statistically significant.ConclusionCXL may be an effective option in stabilizing keratoconus. Further long-term follow-up studies will be necessary to assess the persistence of CXL.
| S-EPMC4436191 | biostudies-literature
Project description:Previous studies investigating the effectiveness of conventional corneal collagen cross-linking (CXL) and transepithelial CXL in keratoconus treatment have reported conflicting outcomes. Therefore, we conducted a meta-analysis to compare the effectiveness of these treatments. We searched MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials for prospective randomized controlled trials (RCTs) with no restrictions. We included visual acuity (corrected distance visual acuity, uncorrected distance visual acuity) and corneal keratometry (K) as primary outcome parameters, and spherical equivalent, central corneal thickness (CCT), and endothelial cell density, as secondary parameters. We finally included seven reports (including six RCTs involving 305 participants and 344 eyes). Our analysis revealed significant postoperative differences in average K and CCT values between conventional and transepithelial CXL-treated patients [K: weighted mean difference (WMD) = 0.79, 95% confidence interval (CI) = 0.04-1.53, p = 0.04; CCT: WMD = 4.53, 95% CI = 0.42-8.64, p = 0.03]. In contrast, we did not find any significant differences in visual acuity, flattest K value, steepest K value, cylinder K value, apex K value, spherical equivalent, or endothelial cell density between groups. In conclusion, transepithelial CXL has a more protective influence on corneal thickness than conventional CXL, and results in lesser postoperative corneal flattening. Further investigation of the clinical outcomes of transepithelial CXL is required.
| S-EPMC5886478 | biostudies-literature
Project description:Purpose Most studies of visual development have concentrated on visual development of infants. Only a few studies have extended this to children and determined the point at which visual function becomes truly adult-like. Yet from a clinical and research perspective it is important to know this. This review paper is a discussion of the development of visual acuity and contrast sensitivity into childhood. Methods The literature on subjective (measured with preferential looking or psychophysical methods) and objective (visually-evoked potential) measures of visual acuity and contrast sensitivity was examined with particular emphasis on studies of children over the age of 5 years and those articles that compared different age groups and those that made a comparison with adults. Results Visual acuity was found to be fully mature between the ages of 5 and the mid teenage years, while contrast sensitivity was found to mature fully between the ages of 8 to 19 years. Thus, there is still no clear answer to the fundamental question of when these basic aspects of visual function mature, but it may be later than previously thought. Conclusions Further studies are needed to answer this basic question more precisely and objective measures, such as VEP, may be able to answer this question better than psychophysical methods.
| S-EPMC3972638 | biostudies-literature