Fibrocellular Contraction of a Lamellar Posterior Corneal Graft

Purpose: To report a case of progressive fibrotic contraction of the posterior lamellar graft after initially successful Descemet’s stripping automated endothelial keratoplasty (DSAEK). Methods: Retrospective report of clinical data and histopathological analysis of excised corneal tissue. Results: A 63-year-old woman underwent uncomplicated DSAEK in her left eye due to endothelial dystrophy. During the first months after surgery, her visual acuity was 0.3, and a semilunar contraction gradually appeared at the edge of the graft. Over the following months, the fibrotic changes progressed and visual acuity decreased, with no improvement after uncomplicated cataract surgery. A successful penetrating keratoplasty was performed, and the excised corneal button with an attached posterior lamellar graft was histologically examined. The affected part of the graft consisted of a thickened fibrocellular tissue positive for glycosaminoglycans and smooth muscle actin. Conclusions: The present case demonstrates asymmetric fibrotic contraction of a DSAEK graft

Early findings in a prospective randomised study on three cross-linking treatment protocols: interruption of the iontophoresis treatment protocol

Purpose To present the outcome of the interrupted iontophoresis-assisted treatment arm in an ongoing randomised clinical trial (NCT04427956).Methods A randomised clinical study of corneal cross-linking (CXL) using continuous UV-A irradiation at a rate of 9 mW/cm2 and three different types of riboflavin and riboflavin delivery mode: (1) iso-osmolar dextran-based riboflavin (epithelium-off), (2) hypo-osmolar dextran-free riboflavin (epithelium-off) and (3) iontophoresis-assisted delivery of riboflavin (epithelium-on) for the treatment of progressive keratoconus. Inclusion criteria were an increase in the maximum keratometry value (Kmax) of 1.0 dioptre over 12 months or 0.5 dioptre over 6 months. The primary outcome in evaluating treatment efficacy was Kmax. Recently presented stratified detection limits were used post hoc to confirm the enrolment of patients with truly progressive keratoconus and in the assessment of the need for re-CXL.Results Thirteen patients had been randomised to iontophoresis-assisted CXL when the treatment arm was interrupted; two patients dropped out. Of the remaining 11 patients, 7 were deemed as having truly progressive disease according to the more recent stratified detection limits. The disease continued to progress in three patients according to the original definition (increase in Kmax≥1 D), necessitating re-CXL with epithelium-off CXL. This progression was confirmed by post hoc analysis using the stratified detection limits for progression.Conclusions The iontophoresis-assisted CXL protocol failed to halt further disease progression in 27% of the patients. The failure rate increased to 38% when considering only the patients deemed to have truly progressive disease using the stratified detection limits

Photorefractive Keratectomy in Keratoconus

Purpose: To assess the efficacy and safety of topography-guided photorefractive keratectomy (PRK) for keratoconus and to estimate the subsequent risk of progression. Methods: This is a retrospective follow-up study. Between 1998 and 2013, 28 eyes of 23 patients (age 17-60) with grade 1-3 keratoconus received topography-guided PRK. Corrected-distance visual acuity (CDVA), keratometry, pachymetry, and corneal topography were assessed before, after 3 months, and at a late follow-up of a median of 7 years after the procedure. Postoperative complications including subsequent keratoplasty were noted. Results: Of the 28 eyes, 5 (18%) had undergone corneal transplantation at a median of 7 years (range 3-10) after PRK. Four eyes were not available for follow-up. In the remaining 19 eyes, CDVA was improved in 16 eyes (84.3%), reduced in 2 eyes (10.5%), and unchanged in 1 eye (5.2%). Thus, average CDVA had improved from 0.49 logMAR before PRK to 0.27 logMAR at 3 months, and to 0.24 at the long-term follow-up. The mean spherical equivalent was reduced from -6.2 to -3.7 dpt after 3 months and to -2.1 dpt at the late follow-up. Similarly, the mean cylinder was reduced from -4.2 to -3.0 dpt after 3 months and at the late follow-up. Conclusion: Topography-guided PRK in keratoconus may be effective for reducing myopia and astigmatism and may offer a temporary or permanent alternative to keratoplasty in contact lens-intolerant keratoconus. In the present study, we found a low risk of keratoconus progression after PRK

Association between keratoconus disease severity and repeatability in measurements of parameters for the assessment of progressive disease

Background Progressive keratoconus can lead to severely impaired vision, but there is currently no consensus on the definition of progressive disease. Errors in the measurement of the parameters commonly used to establish progressive disease were evaluated in an attempt to determine the limits at which a true change in the values can be detected. The possible association between measurement error and disease severity was also investigated to evaluate the need for limits based on disease severity. Methods Sixty-one eyes were studied in 61 patients with keratoconus. Four replicate measurements were made in each patient using a Scheimpflug-based tomographic system (denoted the PC) and an auto-keratometer (denoted the AK). The repeatability coefficient, i.e., the level below which differences between two measurements are found in 95% of paired observations, was calculated. Patients were further divided into three groups based on disease severity (parameter magnitude). Results Increasing magnitude of all the keratometric parameters investigated was significantly associated with increasing measurement errors, and thus worse repeatability. The maximum keratometry value (Kmax) was the least repeatable parameter (1.23 D, 95% CI 1.11–1.35 D) and showed the strongest association between parameter magnitude and measurement error. The repeatability coefficient ranged between 0.32 and 1.62 D, depending on disease severity. The most repeatable parameter was the flattest central keratometry value (K1), measured with the PC (0.51 D, 95% CI 0.46–0.56 D) and the AK (0.54 D, 95% CI 0.48–0.59 D). K1 showed the weakest association between parameter magnitude and measurement error. The repeatability coefficient for K1 ranged between 0.40 and 0.54 D when using the PC, and between 0.34 and 0.70 D when using the AK in the three groups. Conclusions The association between the magnitude of the keratometric parameters and their measurement errors suggests that limits should be based on disease severity to ensure reliable detection of progressive keratoconus. Further studies are, however, required