Nienke Soeters

Effective corneal collagen crosslinking in advanced cases of progressive keratoconus

Purpose To evaluate the 1‐year results of corneal collagen crosslinking (CXL) in mild to moderate cases and advanced cases of progressive keratoconus. Setting Department of Ophthalmology, University Medical Center Utrecht, the Netherlands. Design Retrospective cohort study. Methods Eyes with progressive keratoconus had CXL between January 2010 and April 2011. Patients were divided into 2 subgroups as follows: Group 1, mild to moderate keratoconus with a preoperative maximum keratometry (K) of less than 58.0 diopters (D), and Group 2, advanced keratoconus with a maximum K of 58.0 D or more. Visual acuity, refraction, and elevation‐based topography were evaluated at baseline and 12 months after CXL. Results The study comprised 53 eyes of 42 patients. In the overall group, progression was halted in 48 eyes (91%). The CXL‐induced corneal flattening occurred in 11 (42%) of 26 eyes in Group 1 and 20 (74%) of 27 eyes in Group 2. Five of 7 keratoconus indices improved 12 months after CXL. The failure rate was comparable in the subgroups (3 eyes in Group 1, 2 eyes in Group 2). No major complications occurred in either subgroup. Conclusions Stabilization after CXL was achieved in mild to moderate cases and advanced cases of progressive keratoconus. The amount of failure was comparable in the 2 subgroups. The CXL‐induced flattening was more pronounced in the advanced subgroup. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Corneal cross-linking for treatment of progressive keratoconus in various age groups.

PURPOSE To compare the effect of corneal cross-linking (CXL) for keratoconus in various age groups and to investigate the influence of the topographic cone location on the outcome of CXL. METHODS This cohort study included 95 patients (119 eyes) diagnosed as having progressive keratoconus who underwent epithelium-off standard protocol CXL from January 2010 through May 2012. For statistical analysis, patients were divided into three age groups: pediatric patients (< 18 years), adolescent patients (18 to 26 years), and adults (> 26 years). Visual acuity and refraction, topography, intraocular pressure, and endothelial cell counts were recorded preoperatively and postoperatively. RESULTS Topographic cones were located more centrally in pediatric corneas (0.85 ± 0.66 mm) compared to adolescent corneas (1.49 ± 0.76 mm, P = .002) and adult corneas (1.86 ± 0.99 mm, P < .001). Pediatric corneas flattened 1 year after CXL by a mean of 1.8 diopters (D), compared to 1.1 D in the other age groups. Central cones (0 to 1 mm) were steeper (62.3 ± 8.3 D) before treatment than peripheral cones (3 to 4 mm) (55.9 ± 8.9 D). One year after CXL, corrected distance visual acuity improved in all age groups, with the highest improvement in pediatric eyes (-0.23 ± 0.40 logMAR, P = .044). CONCLUSIONS Before CXL, cones of pediatric keratoconic corneas were located more centrally than in the two older age groups. After CXL, pediatric corneas showed more corneal flattening and more corrected distance visual acuity improvement. Pediatric CXL was equally safe compared to adolescent and adult CXL.

Corneal Cross-Linking for Pediatric Keratoconus: Long-Term Results.

Purpose: To assess the efficacy and safety of cross-linking in pediatric patients with keratoconus and to provide a systematic literature overview regarding this subject. Methods: In this prospective cohort, 54 eyes of 36 pediatric patients with keratoconus underwent standard epithelium-off cross-linking. Follow-up measurements taken up to 5 years after treatment were compared with baseline values. Logistic regression was used to identify the underlying cause in case of progression despite treatment. Finally, a systematic search was performed in PubMed and Embase, and data were extracted and summarized. Results: At all follow-up visits up to 5 years, maximum keratometry values improved significantly (mean change at 5 years −2.06 diopters (D), P = 0.01); moreover, average keratometry, uncorrected distance visual acuity, and corrected distance visual acuity improved at all follow-up times, though not always to the level of statistical significance. In 12 eyes (22%), keratoconus had progressed by ≥1.0 D by the last follow-up visit, despite corneal cross-linking. Cones that were more decentralized were identified as the underlying cause of disease progression. The systematic search yielded 17 unique articles: 10 articles on epithelium-off cross-linking, 2 on accelerated cross-linking, 2 on transepithelial cross-linking, 1 on both epithelium-off and transepithelial cross-linking, and 2 on transepithelial cross-linking with iontophoresis. Conclusions: Our long-term follow-up reveals that epithelium-off cross-linking is both apparently safe and effective when used to prevent keratoconus progression in pediatric patients. However, disease progression occurred in 22% of the treated eyes; this progression was attributed to a more decentralized cone location.

A multivariate analysis and statistical model for predicting visual acuity and keratometry one year after cross-linking for keratoconus.

PURPOSE To investigate putative prognostic factors for predicting visual acuity and keratometry 1 year following corneal cross-linking (CXL) for treating keratoconus. DESIGN Prospective cohort study. METHODS This study included all consecutively treated keratoconus patients (102 eyes) in 1 academic treatment center, with minimal 1-year follow-up following CXL. Primary treatment outcomes were corrected distance visual acuity (logMAR CDVA) and maximum keratometry (K(max)). Univariable analyses were performed to determine correlations between baseline parameters and follow-up measurements. Correlating factors (P ≤ .20) were then entered into a multivariable linear regression analysis, and a model for predicting CDVA and K(max) was created. RESULTS Atopic constitution, positive family history, and smoking were not independent factors affecting CXL outcomes. Multivariable analysis identified cone eccentricity as a major factor for predicting K(max) outcome (ß coefficient = 0.709, P = .02), whereas age, sex, and baseline keratometry were not independent contributors. Posttreatment visual acuity could be predicted based on pretreatment visual acuity (ß coefficient = -0.621, P < .01, R(2) = 0.45). Specifically, a low visual acuity predicts visual improvement. A prediction model for K(max) did not accurately estimate treatment outcomes (R(2) = 0.15). CONCLUSIONS Our results confirm the role of cone eccentricity with respect to the improvement of corneal curvature following CXL. Visual acuity outcome can be predicted accurately based on pretreatment visual acuity. Age, sex, and K(max) are debated as independent factors for predicting the outcome of treating keratoconus with CXL.

Effect of the eyelid speculum on pachymetry during corneal collagen crosslinking in keratoconus patients

Purpose To compare central corneal thickness (CCT) with and without using an eyelid speculum during corneal collagen crosslinking (CXL). Setting University Medical Center Utrecht, Utrecht, the Netherlands. Design Prospective nonrandomized comparative study. Methods Eyes with progressive keratoconus were treated by CXL and consecutively divided into 2 groups. In Group A, an eyelid speculum remained in place throughout the entire CXL procedure. In Group B, the eyelids remained closed during the 30‐minute riboflavin instillation. Intraoperative ultrasound pachymetry measurements were performed at different timepoints. The visual acuity, refraction, keratometry, pachymetry, and endothelium were evaluated 6 months after CXL. The main outcome measures were intraoperative CCT measurements and the clinical CXL effect after 6 months. Results Fifty‐two eyes (50 patients) were treated. After riboflavin instillation, a statistically significant difference in CCT reduction was found between the 2 groups (P < .001), with a mean CCT decrease of 62 &mgr;m ± 53 (SD) (13% ± 11%) in Group A and 11 ± 35 &mgr;m (2% ± 8%) in Group B. No statistically significant between‐group differences were found after epithelial removal or ultraviolet‐A (UVA) irradiation. Six months after CXL, no statistically significant between‐group difference was found in the visual acuity, refraction, keratometry, pachymetry, or endothelium. Conclusions Avoidance of an eyelid speculum during riboflavin instillation resulted in less CCT reduction during CXL. This finding could increase the chance of attaining the required pachymetry safety margin for applying UVA and thus decrease the chance of premature CXL treatment termination. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Corneal Crosslinking for Progressive Keratoconus in Four Children

The authors describe four children with progressive keratoconus treated by corneal crosslinking (CXL). The current CXL guidelines recommend treatment of patients 18 years and older. Nevertheless, keratoconus can rapidly progress in young teenagers. CXL could be a safe procedure to prevent a keratoplasty at a young age.

Scleral lens influence on corneal curvature and pachymetry in keratoconus patients

OBJECTIVES To investigate the influence of full scleral lenses on corneal curvature and pachymetry in keratoconus patients. METHODS In this intervention study, 20 eyes of 14 patients were measured by Scheimpflug imaging (Pentacam HR, Oculus) at two time points: directly and ≥1 week after scleral lens removal. Steep, flat and maximal keratometry (K(steep), K(flat) and K(max)) and optical pachymetry were analyzed. A generalized estimating equation analysis was performed to correct for paired eyes. RESULTS Directly after scleral lens removal, all three curvature parameters were significantly flatter compared to ≥1 week after scleral lens removal. Average K(steep) was 0.7 diopter (D) lower (P<0.001), average K(flat) was 0.5D lower (P=0.037) and average K(max) was 1.1D lower (P<0.001). Directly after scleral lens removal, average optical pachymetry was ±2.5% higher (P<0.001) compared to ≥1 week after scleral lens removal. CONCLUSIONS Although scleral lenses do not mechanically touch the cornea, curvature and pachymetry seem to be influenced by scleral lens wear in keratoconus patients. The duration of these changes remain unclear.

Scleral Lens Tolerance after Corneal Cross-linking for Keratoconus

Purpose Subjective and objective evaluation of scleral lens tolerance and fitting before and after corneal cross-linking (CXL) for progressive keratoconus. Methods In this prospective cohort, evaluations were made of 18 unilateral eyes in patients who underwent CXL and had been wearing scleral lenses before the procedure. All the patients gave informed consent; they were able to cooperate with the study, were eligible for CXL, had been wearing well-fitting scleral lenses for at least 3 months, and had no other active ocular disease. Data were collected before and 1 year after CXL. Outcome measures were changes in clinical and subjective scleral lens performance. The following components were studied: scleral lens corrected distance visual acuity, scleral lens specifications, scleral lens fit, wearing time, and subjective measures on visual analogue scale questionnaires (1 to 100 mm). Results There was no significant change in scleral lens corrected distance visual acuity (p = 0.632). Sixty-one percent of eyes needed a scleral lens fit and/or power change. Wearing time (median, 16 hours per day) and subjective tolerance were found to be stable. Conclusions Scleral lens tolerance after CXL appeared to be stable.

Higher-order aberrations 1 year after corneal collagen crosslinking for keratoconus and their independent effect on visual acuity.

Purpose To evaluate the effect of corneal collagen crosslinking (CXL) in progressive keratoconus patients on higher‐order aberrations (HOAs) and the effect of change in HOAs on visual acuity between baseline and 1 year after CXL. Setting Tertiary academic referral center, Utrecht, the Netherlands. Design Prospective cohort study. Methods This study included consecutive keratoconus patients who were treated with epithelium‐off CXL and followed for a minimum of 1 year. The following corneal HOAs were measured with Scheimpflug tomography (Pentacam HR type 70900): coma, trefoil, spherical aberration, and total corneal HOAs. A 2‐tailed paired‐samples t test was used to compare baseline and postoperative aberrations. Multivariable linear regression was applied to assess the independent effects of HOA subtypes on changes in uncorrected (UDVA) and corrected (CDVA) distance visual acuity. Results Overall, the degree of corneal HOAs in the patient cohort (N = 187) was relatively unchanged after CXL, with a mean change of −1.34% (P = .272). Horizontal coma contributed most to the total amount of HOAs but was virtually unchanged on average. The HOA subtype of spherical aberrations decreased significantly (−15.68%) (P < .001). There was no effect of the change in HOAs on the change in CDVA; however, there was a significant effect of the change in horizontal coma on the change in UDVA (P = .003; B −0.475). Conclusions Corneal HOAs in general were relatively unchanged from baseline to 1 year after CXL in eyes with progressive keratoconus. A change in horizontal coma had a strong and independent effect on UDVA. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned.

Standard and hypoosmolar corneal cross-linking in various pachymetry groups

Purpose To investigate the influence of corneal thickness on the outcome of corneal cross-linking (CXL) for progressive keratoconus. Methods In this cohort study, 72 unilateral eyes were treated by CXL and divided into three groups according to central corneal thickness (CCT) measured by ultrasound pachymetry after 30-minute riboflavin. Group 1 (CCT <400 &mgr;m) underwent hypoosmolar CXL; group 2 (CCT 400 to 460 &mgr;m) and group 3 (CCT >460 &mgr;m) underwent standard CXL. Visual acuity, refraction, topography, ultrasound and optical pachymetry, intraocular pressure, endothelial cell count, and complications were evaluated 1 year post-CXL. Results Ultrasound CCT after riboflavin instillation decreased significantly in groups 1 and 2 (−57 ± 44 &mgr;m and −39 ± 23 &mgr;m, respectively) and increased in group 3 (+15 ± 37 &mgr;m). One year post-CXL, maximal keratometry decreased significantly in group 2. Keratoconus progression was halted in 92% (group 1), 97% (group 2), and 86% (group 3). Optical pachymetry decreased significantly in all groups. Corrected distance visual acuity improved significantly in groups 1 and 3. No significant difference was found in visual acuity, keratometry, optical pachymetry, or endothelial cell density change between groups. Complication rates were comparable between the groups; there was no significant difference in CXL failure (p = 0.687) or corrected distance visual acuity loss (p = 0.617). Conclusions During CXL, corneas with CCT less than or equal to 460 &mgr;m seem to dehydrate faster than corneas with CCT greater than 460 &mgr;m. Both standard and hypoosmolar CXL are safe and effective treatments, with comparable amounts of stabilization after 1 year.