Pediatric Corneal Cross-linking: Comparison of Visual and Topographic Outcomes Between Conventional and Accelerated Treatment

Pediatric Keratoconus

Keratoconus is a common pediatric corneal disease, leading to vision impairment and amblyopia. Compared to its adult counterpart, pediatric keratoconus has an advanced presentation, rapid progression, higher incidence of complications such as corneal hydrops, and potential impact on the child's quality of life. It typically manifests during puberty and can evolve rapidly to more severe stages if left untreated. This rapid progression underscores the importance of early diagnosis through regular screening in pediatric populations and vigilant monitoring of pediatric keratoconus suspects. Concomitant ocular allergies, ocular anomalies, systemic diseases (eg. syndromes), and poor compliance with contact lenses might impede prompt intervention and frequently postpone rehabilitation. Corneal collagen crosslinking is a crucial intervention in the management of pediatric keratoconus because it strengthens the corneal microstructure and halts the disease's progression. When conservative measures fail, keratoplasty remains a viable option with generally favorable outcomes, though with unique challenges in post-operative care, including concerns related to sutures, long-term graft survival and need for repeated examinations under anesthesia. A multidisciplinary approach involving ophthalmologists, optometrists, pediatricians, and other healthcare professionals, focusing on early diagnosis and timely intervention, is essential for the comprehensive management of pediatric keratoconus and to mitigate its impact on children's lives.

Management of experimental trabeculectomy filtering blebs via crosslinking of the scleral flap inhibited vascularization

PURPOSE

The aim of this study was to evaluate whether UVA-light-activated riboflavin-induced collagen crosslinking (UVA-CXL) can maintain the function of filtering blebs after trabeculectomy (TRAB) in rabbits.

METHODS

Thirty-six healthy rabbits were randomized to one of the following groups with 12 rabbits in each group: Trabeculectomy group (TRAB group), trabeculectomy combined with CXL group (CXL group), and trabeculectomy combined with MMC group (MMC group). Six rabbits of each group were performed with intraocular pressure (IOP), optical coherence tomography (OCT), and OCT angiography (OCTA). Bleb structure was observed via hematoxylin & eosin (H&E) and Masson staining. Immunohistochemistry, proteomic study, western blot, and tensile test were performed between CXL group and the control. In vitro, cell viability was evaluated by CCK-8 and Calcein/PI staining. TRPV4 and VEGF-a expression levels were measured by Q-PCR. Ca2+ concentration was observed with Fluo-4 AM.

RESULTS

The IOP and bleb median survival day were significantly modified in CXL (5.92 ± 0.32 mmHg and 15.5 days) than TRAB group (7.50 ± 0.43 mmHg and 9 days). The bleb area and height increased. CXL inhibited vascularization, and vascularization peaked at postoperative day (POD) 14 and then decreased gradually. In proteomic analyses, Z disc, actin filament binding, and sarcomere organization were significantly enriched. CXL inhibited scleral stress‒strain in tensile tests. Compared with TRAB group, TRPV4 expression was significantly increased, but VEGF-a and TGF-β1 levels were reduced in the CXL group in western blot. Meanwhile, TRPV4 expression colocalized with CD31. In vitro, CXL inhibited HUVECs cell viability. After CXL, expression level of TRPV4 was increased and calcium influx was activated, but VEGF-a was decreased in HUVECs.

CONCLUSIONS

This study demonstrates that intraoperative UV-RF CXL can significantly improve the success rate of TRAB via inhibiting filtering bleb vascularization. CXL increased sclera stiffness, in turn, induced TRPV4 activation, thus contributing to vascular endothelial cells suppression.

Accelerated Corneal Cross-linking in Pediatric Patients with Progressive Keratoconus: 12-Month Follow-up Results

PURPOSE

To evaluate effectiveness and safety of accelerated corneal cross-linking (CXL) in the treatment of keratoconus in pediatric patients.

SETTING

Tertiary care hospital.

DESIGN

Retrospective observational study.

METHODS

In this study, case series of patients 18 years old or younger with progressive keratoconus who underwent accelerated CXL were observed. All consecutive patients underwent accelerated CXL with setting of 9 mW/cm2 for 10-minute Ultraviolet-A radiation, corresponding to a total dose of 5.4 J/cm2. Preoperative and 12-month postoperative data including uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (BDVA), keratometry (K) measurements, mean spherical, and cylindrical refraction were evaluated.

RESULTS

The group consisted of 28 eyes from 14 patients (10 males and 4 females). Mean age of the patients was 16.9 years (11-18 years). UDVA did not change significantly from 0.71 ± 0.54 to 0.65 ± 0.43 logMAR (P = 0.41). BDVA improved significantly from 0.30 ± 0.35 to 0.21 ± 0.34 (P = 0.006). The steep K-value decreased from 48.4 ± 4.3 to 48.0 ± 4.6 diopters, but there was no significant change in steep K-value (P = 0.35). There was no significant change in flat and mean K-value (P > 0.05). Mean spherical and cylindrical refraction were not significantly altered (P > 0.05). One patient with vernal keratoconjunctivitis showed sterile peripheral corneal infiltrates. Patient was treated with topical corticosteroids, antibiotics, and artificial tears.

CONCLUSION

The findings revealed that accelerated CXL is an effective and safe procedure that halts the progression of keratoconus in pediatric patients.

Diagnosis and management of keratoconus in the paediatric age group: a review of current evidence

The diagnosis and management of keratoconus in the paediatric age group presents additional challenges to those encountered in adults. The most significant of these, encountered in some young patients, are delayed presentation of unilateral disease, more advanced disease at diagnosis, difficulty in obtaining reliable corneal imaging, faster rates of disease progression and challenges in contact lens management. The stabilisation effect of corneal cross-linking (CXL), more extensively studied in adults with randomised trials and long-term follow-up, has been much less rigorously examined in children and adolescents. The high heterogeneity of published studies in younger patients, particularly in the choice of tomography parameters designated as primary outcome measures and the definitions of progression, indicates that improved standardisation for future studies on CXL will be necessary. There is no evidence that corneal transplant outcomes in young patients are poorer than those in adults. This review provides a current perspective on the optimal diagnosis and treatment of keratoconus in children and adolescents.

Three-year follow-up of accelerated versus standard corneal cross-linking in paediatric Keratoconus

PURPOSE

Standard corneal collagen cross-linking (S-CXL) is an effective treatment to arrest Keratoconus (KC) progression in children. Less is known on the long-term efficacy of accelerated CXL (A-CXL) in paediatric populations.

METHODS

A historical cohort analysis of paediatric patients (≤18 years) with KC who underwent S-CXL and A-CXL at two tertiary referral centres in Israel between 2010-2017. Preoperative and 3-year postoperative evaluation included changes in visual acuity (best spectacle corrected [BSCVA]) and uncorrected [UCVA]), refractive errors, and keratometric data.

RESULTS

Ninety-three eyes of 93 patients were analysed (A-CXL: n = 39; S-CXL: n = 54). Baseline characteristics were similar between groups. Both groups showed a significant improvement in visual acuity compared to baseline (S-CXL: 0.810-0.602 LogMAR UCVA; A-CXL: 0.890-0.306 LogMAR UCVA, p < 0.05 for both). Improvement in BSCVA and UCVA following A-CXL was non-inferior to S-CXL (< ± 0.2 LogMAR). Kmax decreased by a mean of 0.98 ± 5.56 dioptres following S-CXL (p = 0.02) and by 1.48 ± 8.4 dioptres following A-CXL (p = 0.015). Thinnest pachymetry decreased following both treatments (S-CXL: by 26.8 ± 40.7 µm, p = 0.001, A-CXL: by 10.2 ± 13.4 µm, p = 0.028), the difference between groups was within the non-inferiority margin (< ± 10 µm).

CONCLUSIONS

Paediatric patients followed for three years after A-CXL showed improved visual function, reduced corneal astigmatism and Kmax, and decreased thinnest corneal thickness. A-CXL was non-inferior to S-CXL at three years in terms of best-corrected and uncorrected visual acuity, thinnest pachymetry, and astigmatism. For Kmax, non-inferiority could not be concluded.

Long-term Safety and Efficacy of Corneal Collagen Crosslinking in a Pediatric Group With Progressive Keratoconus: A 7-year Follow-up

PURPOSE

To assess effectiveness and safety of corneal crosslinking (CXL) to reduce keratoconus (KC) progression and improve visual acuity among children with progressive KC and to analyze the use of 20% dextran-based (Dextran) and 1% hydroxypropyl methylcellulose-based (HPMC) riboflavin.

DESIGN

Prospective, clinical cohort study METHODS: Standard CXL (SCXL) was performed in 74 eyes (58 patients, 45 males, mean age 13.0 ± 2.1 years): 53 eyes with HPMC and 21 with Dextran. Examinations were performed at baseline, 3 and 6 months, and 1, 2, 3, 4, 5, and 7 years of follow-up, including uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), a complete ophthalmologic examination, anterior segment ocular coherence tomography, Scheimpflug corneal tomography, and specular microscopy.

RESULTS

UDVA and CDVA improved at all periods with statistically significant differences in CDVA at 1, 2, and 3 years. Compared with baseline, maximum K (Max K) reduced throughout the 7-year follow-up. Mean thinnest pachymetry (Th Pachy) decreased significantly at 3 months and remained low; in the Dextran group, the Th Pachy mean value returned to baseline 6 months postoperatively. After CXL, 1.5 diopter progression in max K was 1.4% to 14.6% of eyes; worsening was found at 4 to 7 years postoperatively.

CONCLUSION

SCXL reduced KC progression in children up to 7 years of follow-up and revealed improvement and stability of UDVA and CDVA in 82% of eyes. For visual acuity and KC stability, no statistically significant difference was observed between Dextran-HPMC. The HPMC group showed persistent cornea thinning, raising concerns about its use in SCXL.

Progression of Pediatric Keratoconus After Corneal Cross-Linking: A Systematic Review and Pooled Analysis

PURPOSE

Corneal collagen cross-linking (CXL) is an effective treatment to slow down keratoconus (KC) progression in adults. Several studies have also shown efficacious outcomes in pediatric populations, yet no systematic analysis has been performed and no accepted definition for progression is available in children after CXL. This study aimed to establish the most commonly used criteria for progression and to conduct a systematic review of the literature with pooled analysis to assess children's keratoconus progression after CXL.

METHODS

A systemic literature review combined with pooled analysis was performed on full-length studies of KC after CXL treatment in a pediatric population and the methods used to report progression were analyzed.

RESULTS

Thirty-seven studies (2078 eyes) were identified on the rates of KC progression after CXL. The most common method to report progression was increased Kmax, Kmean, or Ksteep by ≥1.0 diopter (78.3% of studies). Using these criteria, the mean pooled progression rate after epithelium-off CXL was 9.9% (95% confidence interval: 6.1% -14.6%, total pooled sample size: 1508 eyes) with high heterogeneity between studies [I 2 = 86.48% (95% confidence interval: 80.98 - 90.39), P < 0.0001].

CONCLUSIONS

When considering KC progression after CXL in children, with an increase in Kmax, Kmean, or Ksteep ≥ 1.0 diopter, the progression risk was roughly 10%. We encourage clear quantitative reporting of KC progression in future studies evaluating CXL efficacy in pediatric populations.

Long-term Effects of Riboflavin Ultraviolet-A-Induced CXL With Different Irradiances on the Biomechanics of In Vivo Rabbit Corneas

PURPOSE

To evaluate the long-term effects of ultraviolet-A corneal cross-linking (CXL) with different irrandiances on the biomechanical properties of rabbit corneas and the corresponding changes in stromal microstructure.

METHODS

The study involved the left eyes of 85 healthy white Japanese rabbits, randomly divided into five groups (n = 16 to 18 each). After removing the epithelium, the first four groups were exposed to riboflavin (0.22% concentration by volume) and ultraviolet-A (370 nm) at different CXL irradiations but with the same total dose (5.4 J/cm2). The four groups were defined as standard CXL (SCXL; 3 mW/cm2 for 30 minutes, n = 17), accelerated CXL1 (ACXL1; 9 mW/cm2 for 10 minutes, n = 16), accelerated CXL2 (ACXL2; 18 mW/cm2 for 5 minutes, n = 17), and accelerated CXL3 (ACXL3; 30 mW/cm2 for 3 minutes, n = 17). The control group (n = 18) was treated with riboflavin without ultraviolet-A exposure. Nine months after CXL, 10 corneas from each group were tested ex vivo under inflation, and the tangent modulus (Et) was estimated using an inverse analysis process. The remaining six to eight specimens in each group were examined by electron microscopy to determine the mean fibril diameter and interfibrillar spacing.

RESULTS

The SCXL and ACXL1 groups showed statistically significant differences in Et at all stresses (0.005, 0.010, and 0.015 MPa) analyzed compared to the control group (all P < .01), but the differences were non-significant in the ACXL3 group (P = 1.000, .785, and .679, respectively). For the ACXL2 group, there was no statistical difference in Et under the low stress of 0.005 MPa (P = .155), but the differences became significant at 0.010 and 0.015 MPa when compared with the control group (all P < .05).

CONCLUSIONS

CXL had a significant effect on corneal biomechanics in both standard and accelerated procedures. However, standard CXL was the most effective, and this effectiveness decreased gradually with increasing ultraviolet-A power intensity. [J Refract Surg. 2022;38(6):389-397.].

Comparison of Efficacy and Safety Between Standard, Accelerated Epithelium-Off and Transepithelial Corneal Collagen Crosslinking in Pediatric Keratoconus: A Meta-Analysis

Purpose

The purpose of the study is to compare the efficacy of standard epithelium-off CXL (SCXL), accelerated epithelium-off CXL (ACXL), and transepithelial crosslinking CXL (TECXL) for pediatric keratoconus.

Methods

A literature search on the efficacy of SCXL, ACXL, and TECXL [including accelerated TECXL (A-TECXL)] for keratoconus patients younger than 18 years was conducted using PubMed, Cochrane Library, ClinicalTrials.gov, and EMBASE up to 2021. Primary outcomes were changes in uncorrected visual acuity (UCVA) and maximum keratometry (Kmax) after CXL. Secondary outcomes were changes in best-corrected visual acuity (BCVA), mean refractive spherical equivalent (MRSE), and central corneal thickness (CCT). Estimations were analyzed by weighted mean difference (WMD) and 95% confidence interval (CI).

Results

A number of eleven identified studies enrolled 888 eyes (SCXL: 407 eyes; ACXL: 297 eyes; TECXL: 28 eyes; A-TECXL: 156 eyes). For pediatric keratoconus, except for a significant greater improvement in BCVA at 24-month follow-up in SCXL (WMD = –0.08, 95%CI: –0.14 to –0.01, p = 0.03, I² = 71%), no significant difference was observed in other outcomes between the SCXL and ACXL groups. SCXL seems to provide greater changes in UCVA (WMD = –0.24, 95% CI: –0.34 to –0.13, p < 0.00001, I² = 89%), BCVA (WMD = –0.09, 95% CI: –0.15 to –0.04, p = 0.0008, I² = 94%), and Kmax (WMD = –1.93, 95% CI: –3.02 to –0.85, p = 0.0005, I² = 0%) than A-TECXL, with higher incidence of adverse events.

Conclusion

For pediatric keratoconus, both SCXL and ACXL appear to be comparable in the efficacy of visual effects and keratometric outcomes; SCXL seems to provide greater changes in visual and pachymetric outcomes than A-TECXL.

Corneal Cross-Linking as Treatment in Pediatric Keratoconus: Comparison of Two Protocols

Introduction

Keratoconus is a progressive corneal disease commonly treated by collagen cross-linking (CXL). Accelerated protocols have recently become common. This study sought to compare the outcomes of accelerated and standard CXL in terms of visual acuity, keratometry, and tomographic parameters in pediatric population.

Methods

We retrospectively reviewed the files of pediatric patients who underwent standard and accelerated CXL for keratoconus in our hospital, between October 2014 and March 2018. Changes in uncorrected distance visual acuity (UCDVA), best corrected distance visual acuity (BCDVA), tomographic keratometry parameters (K_max, K_steep, K_flat, K_mean), and endothelial density count (EDC) were assessed before and at 6 and 12 months following treatment. The analysis included intergroup and intragroup comparisons.

Results

This study included 53 eyes (44 patients). Fourteen eyes were treated with standard CXL (S-CXL, 3 mW/cm², 30 min), while 39 underwent accelerated CXL (A-CXL, 9 mW/cm², 10 min). Intergroup comparison found insignificant differences between groups, with the exception of better results for UCDVA in the S-CXL group after 12 months (P = 0.03). In this study, there was no significant difference between the two protocols postoperatively in BCDVA, K_max, K_mean, pachymetry, or corneal astigmatism.

Conclusion

A-CXL is as safe and effective as S-CXL for stabilizing progressive keratoconus in pediatric population. Larger-sample-size studies with a longer follow-up time are required. Considering the long-term results of 9 mW A-CXL and its safety and efficacy profile, it should be preferred to S-CXL for reducing treatment time and improving patients' comfort.

Effect of Corneal Cross-linking versus Standard Care on Keratoconus Progression in Young Patients: The KERALINK Randomized Controlled Trial

PURPOSE

To examine the efficacy and safety of corneal cross-linking (CXL) for stabilization of progressive keratoconus.

DESIGN

Observer-masked, randomized, controlled, parallel-group superiority trial.

PARTICIPANTS

Sixty participants 10 to 16 years of age with progressive keratoconus, one eye of each deemed the study eye.

METHODS

The study eye was randomized to either CXL plus standard care or standard care alone, with spectacle or contact lens correction as necessary for vision.

MAIN OUTCOME MEASURES

The primary outcome was steep keratometry (K2) in the study eye as a measure of the steepness of the cornea at 18 months. Secondary outcomes included keratoconus progression defined as a 1.5-diopter (D) increase in K2, visual acuity, keratoconus apex corneal thickness, and quality of life.

RESULTS

Of 60 participants, 30 were randomized to CXL and standard care groups. Of these, 30 patients in the CXL group and 28 patients in the standard care group were analyzed. Mean K2 in the study eye 18 months after randomization was 49.7 D (standard deviation [SD], 3.8 D) in the CXL group and 53.4 D (SD, 5.8 D) in the standard care group. The adjusted mean difference in K2 in the study eye was -3.0 D (95% confidence interval [CI], -4.9 to -1.1 D; P = 0.002), favoring CXL. Adjusted differences between groups in uncorrected and corrected vision favored eyes receiving CXL: -0.31 logarithm of the minimum angle of resolution (logMAR; 95% CI, -0.50 to -0.11 logMAR; P = 0.002) and -0.51 logMAR (95% CI, -1.37 to 0.35 logMAR; P = 0.002). Keratoconus progression in the study eye occurred in 2 patients (7%) randomized to CXL compared with 12 patients (43%) randomized to standard care. The unadjusted odds ratio suggests that on average, patients in the CXL arm had 90% (odds ratio, 0.1; 95% CI, 0.02-0.48; P = 0.004) lower odds of experiencing progression compared with those receiving standard care.

CONCLUSIONS

CXL arrests progression of keratoconus in the majority of young patients. CXL should be considered as a first-line treatment in progressive disease. If the arrest of keratoconus progression induced by CXL is sustained in longer follow-up, particular benefit may be derived from avoiding a later requirement for contact lens wear or corneal transplantation.

Efficacy of Conventional Versus Accelerated Corneal Cross-linking in Pediatric Keratoconus: Two-Year Outcomes

PURPOSE

To compare the efficacy and safety of accelerated corneal cross-linking (CXL) with conventional CXL in pediatric patients with keratoconus.

METHODS

Consecutive patients with keratoconus received either accelerated CXL (9 mW/cm² irradiance for 10 minutes) or conventional CXL (3 mW/cm² irradiance) for 30 minutes. Visual acuities (uncorrected [UDVA] and corrected [CDVA] distance visual acuity, logMAR), spherical error, cylindrical error, spherical equivalent, and keratometric values were recorded. Follow-up measurements were compared with baseline values.

RESULTS

The study enrolled 48 eyes: 22 eyes had accelerated CXL (mean age: 16.0 ± 1.7 years) and 26 eyes had conventional CXL (mean age: 15.7 ± 1.6 years). Compared with preoperative values, all mean keratometric values significantly improved in the accelerated CXL group (flat [K1]: Δ = -0.64 D, P < .0001, steep [K2]: Δ = -0.63 D, P = .009 and Kmax: Δ = -0.55 D, P = .028), but no significant changes were observed in the mean UDVA and CDVA. In the conventional CXL group, all mean keratometric values and CDVA significantly improved (K1: Δ = -0.65 D, P = .017, K2: Δ = -0.87 D, P = .006, Kmax: Δ = -1.47 D, P = .011). No significant changes were observed in refractive error in either CXL group. There were no significant differences in the keratometric readings, visual acuities, or refractive error between the two groups at the 2-year follow-up.

CONCLUSIONS

Both conventional and accelerated CXL protocols appear to be effective in stabilizing keratoconus progression in pediatric patients. Improved CDVA was also observed in the conventional CXL group. Accelerated CXL, with its advantage of shorter treatment duration, may be an alternative in pediatric patients. [J Refract Surg. 2020;36(4):265-269.].

Three-year follow-up in advanced pediatric keratoconus: thin corneas may not have pachymetry properly assessed after crosslinking

AIM

To analyze the crosslinking (CXL) effects in pediatric keratoconus, and to identify the patients' corneal characteristics whose pachymetry could not be adequately evaluated by Scheimpflug method after procedure.

METHODS

Consecutive pediatric patients with progressive keratoconus underwent CXL were included. Best-corrected visual acuity (BCVA) and spheric equivalent (SE) were measured before and after CXL. After CXL, groups 1 and 2 were divided based on the posterior surface Pentacam quality specifications (QS): "OK" (Group 1) and "not OK" (Group 2). The mean (RmF and RmB) and minimum (RminF and RminB) radius of curvatures of the anterior and posterior corneal surfaces, and the thinnest pachymetry (Pmin) were measured preoperatively at 3, 6, 12, 24, and 36mo. Haze was annotated.

RESULTS

Twenty-six patients (14 men, mean age 14±1.8y) and median Kmax of 59.9 D initially and 61.4 D preoperatively were treated. BCVA was not different before and 24mo after CXL. Group 2 statistically differed to group 1 in that SE was more myopic before and with no difference 24mo after CXL; RmF and RmB were steeper and Pmin was thinner pre-surgically. Group 2, in which pachymetric changes could not be adequately evaluated after surgery, presented with significant RmF flattening, a shift to hyperopia, and more haze after CXL.

CONCLUSION

Patients whose pachymetry could not be adequately evaluated after CXL had steeper and thinner corneas before surgery. The predictive factors for impaired QS after CXL are RmF, RmB, and Pmin. In advanced keratoconus, alternative methods to analyze pachymetry and the posterior surface should be considered.

Accelerated and Standard Corneal Cross-Linking Protocols in Patients with Down Syndrome: A Non-inferiority Contralateral Randomized Trial

Introduction

To compare the results of an accelerated corneal cross-linking (CXL) protocol (9 mW/cm², 10 min) with the standard CXL protocol (3 mW/cm², 30 min) in patients with Down syndrome (DS) who have keratoconus (KC).

Methods

Twenty-seven 10- to 20-year-old patients with DS who had bilateral progressive KC were enrolled in a contralateral randomized trial and completed 2 years of follow-up examinations. Fellow eyes were randomly allocated to the accelerated CXL group or the standard CXL group. The main outcome measure was change in maximum keratometry (K_max) centered on the steepest point (zonal K_max − 3 mm) with a non-inferiority margin of 1.0 diopter (D). Vision and refraction tests, ophthalmic examinations, and corneal tomography were performed at baseline and at 6, 12, and 24 months after CXL. Failure was defined as an increase of ≥ 1.0 D in zonal K_max − 3 mm within a 12-month period.

Results

The mean age (± standard deviation) of the patients was 15.71 ± 2.40 years. The within-group change in zonal K_max − 3 mm was not significant after 2 years in either group, and within-group zonal K_max − 3 mm remained stable. At 2 years after CXL, the mean change in the zonal K_max − 3 mm was – 0.02 ± 0.81 D and – 0.31 ± 0.86 D in the accelerated CXL and standard CXL groups, respectively (P = 0.088). At 1 year of follow-up, three patients in the accelerated CXL group showed treatment failure (mean change in zonal K_max − 3 mm + 2.12 ± 0.11 D); no patients in the standard CXL group showed treatment failure. At 2 years of follow-up, these three patients showed a decrease of – 0.43 ± 0.18 D in zonal K_max − 3 mm from a baseline value of 55.11 ± 0.32 D. The 2-year trends of the inferior–superior asymmetry and vertical coma were statistically significantly different between the two groups, with the accelerated CXL protocol showing superiority in patients with higher baseline values.

Conclusion

In young patients with Down syndrome, the accelerated CXL protocol was able to halt disease progression and may be an alternative for the standard CXL protocol. In advanced KC, the efficacy of the accelerated approach was delayed and appeared later in the follow-up. In asymmetric cornea, the accelerated CXL resulted in centralization of the corneal cone.

Trial Registration

Iranian Registry of Clinical Trials, IRCT20100706004333N3

Electronic supplementary material

The online version of this article (10.1007/s40123-020-00303-4) contains supplementary material, which is available to authorized users.

Mechanical versus transepithelial phototherapeutic keratectomy epithelial removal followed by accelerated corneal crosslinking for pediatric keratoconus: Long-term results

PURPOSE

To compare the 36-month outcomes of mechanical or transepithelial phototherapeutic keratectomy (PTK) epithelial removal before accelerated corneal crosslinking (CXL) for pediatric keratoconus.

SETTING

Atatürk Training and Research Hospital, Ankara, Turkey.

DESIGN

Retrospective case series.

METHODS

Eyes that had accelerated CXL after mechanical (Group 1) or transepithelial PTK (Group 2) epithelial removal were evaluated preoperatively and 12, 24, and 36 months postoperatively. The uncorrected (UDVA) and corrected distance visual acuities, spherical equivalent (SE), manifest astigmatism, and corneal tomographic and aberrometric parameters were assessed.

RESULTS

The study included 40 eyes of 35 consecutive keratoconus patients younger than 18 years with a 36-month follow-up. Group 1 comprised 15 patients, and Group 2 comprised 20 patients. Both groups had a significant improvement in UDVA (P = .001 and P = .02, respectively) and a significant decrease in maximum keratometry (K) and thinnest corneal thickness (all P < .001) 36 months postoperatively. The improvements in maximum K, topographic astigmatism, and spherical aberration were greater in Group 2 than in Group 1 at 12 months (P = .03, P = .01, and P = .04, respectively). After 12 months, the outcomes in the 2 groups were more similar.

CONCLUSIONS

The initial visual and topographic outcomes of transepithelial PTK ablation were better than those of mechanical epithelium removal before accelerated CXL in pediatric patients with keratoconus. Over the long-term, the results were similar between the 2 groups.

Long-Term Stability With the Athens Protocol (Topography-Guided Partial PRK Combined With Cross-Linking) in Pediatric Patients With Keratoconus

PURPOSE

To evaluate the safety, efficacy, and stability of topography-guided partial PRK combined with corneal cross-linking (CXL) (the Athens Protocol [AP]) in pediatric patients with keratoconus over a 4-year follow-up period.

METHODS

This prospective study included 39 keratoconic eyes of 21 patients younger than 18 years with clinical and imaging evidence of keratoconus progression. Partial topography-guided excimer laser ablation in conjunction with high-fluence CXL was performed in all patients according to the AP. Uncorrected distance visual acuity, corrected distance visual acuity, refraction, keratometry, endothelial cell density, topography, and tomography using both Scheimpflug and optical coherence tomography (OCT) were evaluated for 4 years postoperatively.

RESULTS

At 4 years postoperative, there was significant improvement in mean uncorrected distance visual acuity from 0.51 ± 0.31 (decimal) to 0.65 ± 0.26 (decimal; P < 0.05). Mean corrected distance visual acuity improved from 0.71 ± 0.22 (decimal) preoperatively to 0.81 ± 0.19 (decimal; P < 0.05), respectively. Mean flat keratometry (K1) and mean steep keratometry (K2) readings reduced from 44.95 ± 3.71 D and 49.32 ± 5.05 D, respectively, preoperatively to 43.14 ± 2.95 D and 46.28 ± 4.87 D, respectively, (P < 0.05) at 4 years. The mean anterior maximum keratometry (Kmax) reading reduced from 56.81 ± 2.94 D preoperatively to 48.11 ± 3.17 D at 48 months. The mean index of height decentration was 0.105 ± 0.054 μm preoperatively and 0.049 ± 0.024 (P < 0.05) at 4 years postoperative. Mean preoperative corneal thickness at the thinnest point was 436.7 ± 42.6 μm preoperatively, 392.50 ± 45.68 μm at 12 months postoperative, and 418.42 ± 17.01 μm at 4-year follow-up. Late-onset deep corneal haze, a potential intrinsic complication of this technique in pediatric patients, was encountered in 2 cases at least 1 year after the procedure.

CONCLUSIONS

Long-term results of the AP seem to be safe and effective in pediatric patients, with marked improvement in visual function and keratometric symmetry indices.

Optimal management of pediatric keratoconus: challenges and solutions

Keratoconus (KC) shows several distinctive features in clinical appearance, disease progression, and treatment in children compared with adults. Therefore, diagnostic, clinical care, and therapeutic approaches are different. However, pediatric keratoconus is often undiagnosed and thus untreated in many cases. Once diagnosis has been made, compliance with treatment recommendations is often poor. Pediatric keratoconus also tends to have more rapid progression than in adults; therefore, early detection and treatment are paramount to prevent serious vision impairment, which can affect the child's development. This review of pediatric keratoconus discusses important issues such as worldwide epidemiology, clinical features in children compared to adults, and challenges in diagnosis and treatment and focuses on the most appropriate management strategies based on the best available current evidence.

Analysis of the Outcomes of Combined Cross-Linking with Intracorneal Ring Segment Implantation for the Treatment of Pediatric Keratoconus

PURPOSE

To analyze the visual and refractive outcomes of combined accelerated cross-linking with femtosecond laser intracorneal ring segment implantation for the treatment of pediatric keratoconus.

MATERIALS AND METHODS

This retrospective multicenter noncomparative clinical study included 63 eyes of 37 patients (age, 9-17 years) who underwent between August and September 2016 combined cross-linking with intracorneal ring segment implantation for keratoconus. Preoperative and postoperative (6, 12, and 18 months) uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA), subjective refractions, keratometry (K), and pachymetry measurements were compared.

RESULTS

The postoperative spherical equivalent refraction was within ±1 D, ±2 D, and ±3 D in 19 (30.2%), 27 (42.9%), and 37 (58.8%) eyes, respectively. Only 27 eyes achieved the attempted preoperative spherical equivalent refraction. The mean spherical equivalent refraction significantly improved from -6.01 ± 2.97 to -3.13 ± 2.78 D postoperatively (P < 0.0001). The mean K average reading significantly decreased from 48.75 ± 4.25 to 46.65 ± 3.89 D postoperatively (P < 0.0001). The mean postoperative myopic, astigmatic, and spherical equivalent corrections were -2.17 ± 2.19, -1.52 ± 2.03, and -2.93 ± 2.35 D, respectively. The mean UDVA and CDVA showed significant improvements (0.89 ± 0.33 to 0.40 ± 0.28, P < 0.0001; 0.35 ± 0.31 to 0.25 ± 0.24, P = 0.004; respectively) at 18 months postoperatively. Keratoconus progression, segment migration, and segment extrusion were seen in four (6.4%), one (1.6%), and three (4.7%) eyes, respectively, probably contributing to the lower mean postoperative CDVA.

CONCLUSION

Cross-linking plus is only partially effective for pediatric keratoconus. Despite some improvements in vision and keratometry measures, it resulted in complications such as keratoconus progression, segment extrusion, and segment migration that affected the vision in some patients. These findings suggest an assessment of standard epithelium-off collagen cross-linking as a sole procedure to treat pediatric keratoconus in future studies.