Accelerated versus standard corneal collagen cross-linking in pediatric keratoconus patients: 24 months follow-up results

Purpose

To compare the 24 month visual, refractive, topographic and aberrometric results of the accelerated and standard corneal collagen cross-linking (CXL) in pediatric keratoconus patients.

Improved contact lens fitting after corneal cross-linking in eyes with progressive keratoconus

ObjectivesThe study aimed to assess the possible effects of corneal cross-linking (CXL) on contact lens (CL) fitting in patients with progressive keratoconus who initially had CL intolerance.MethodsA retrospective review was performed of the medical records of patients who had stopped CL wear due to discomfort prior to CXL and who were fitted with CLs after CXL. All eyes were evaluated pre- and 1, 6, 12, 24 months postoperatively. Data collected included pre- and post-CXL refraction, corneal topographic data, uncorrected visual acuity, and best-corrected visual acuity (BCVA). CL comfort was evaluated using the Likert scale post-CXL.ResultsA total of 20 eyes from 14 patients were included in the study. Preoperative Kmax values significantly decreased by 2.8 D at 6 months and by 4.1 D at 12 months after CXL (p < 0.001 for both). CLs were prescribed on average 12 ± 2.5 months after CXL. The mean duration of successful CL wear was 10.4 ± 2.8 months during the follow-up period. Subjective CL comfort scores were satisfactory post-CXL.ConclusionCXL not only halts the progression of keratoconus but may also improve CL tolerance by providing a more regular shaped cornea in these patients. Ongoing corneal topographic changes in the late postoperative period after CXL may have a positive effect on CL fitting.     

Clinical evaluation of different types of contact lenses in keratoconus management

PurposeTo compare the clinical and topographical findings of the keratoconus patients according to the prescribed contact lens type and to investigate the effects of corneal collagen cross-linking (CXL) and cone location on lens selection.MethodsThe records of 301 eyes of 195 keratoconus patients who were prescribed contact lenses were analyzed retrospectively. The eyes were grouped according to the lens type: Soft toric contact lens (STCL), rigid gas-permeable contact lens (RGPCL), hybrid contact lens (HCL) and mini-scleral contact lens (MSCL). The history of having CXL, ophthalmological examination findings, and the topographical findings were compared between the groups. Brown-Forsythe, Chi-square, and post-hoc tests were used to compare the groups. Mann-Whitney U test was used for subgroup analysis. Comparison of the lens-corrected visual acuity (LCVA) and spectacle-corrected visual acuity (SCVA) levels was made with Wilcoxon signed-ranks test.ResultsThere was no significant difference between the groups regarding topographical cone location, CXL history, spherical refraction, and LCVA. The difference between spectacle-corrected visual acuity and LCVA was higher in RGPCL and MSCL groups than STCL group (p=0.01). Keratometry of RGPCL and MSCL groups were higher than STCL and HCL groups (p=0.01, p<0.001). In RGPCL group, eyes with central cones had a higher increase in visual acuity with contact lenses compared to eyes with paracentral cones (p=0.043). STCL and MSCL were mostly prescribed in mild and severe keratoconic eyes, respectively. In RGPCL group, the increase in visual acuity with contact lens was higher in eyes treated with CXL (p= <0.01).ConclusionsWhile STCL and HCL were mostly prescribed in mild keratoconus, RGPCL and MSCL were selected for moderate or advanced disease. If appropriately chosen, all types of contact lenses could result in a good visual acuity level. CXL history did not affect the prescribed lens type. Having central cone location and CXL history in RGPCL group improved visual acuity more efficiently.     

Diagnostic patterns in keratoconus

PurposeTo investigate the current patterns of diagnosis and referral in keratoconus.MethodsA retrospective chart review was performed of patients who had recently been diagnosed with keratoconus and attended dedicated clinics at Antwerp University Hospital, Belgium and Maria Middelares General Hospital, Ghent, Belgium between June 2013 and February 2018. Exclusion criteria included longstanding keratoconus diagnosis, reduced cognitive capabilities and prior surgical procedures (corneal crosslinking, penetrating keratoplasty or any type of refractive surgery).ResultsThree-hundred and ninety-nine patients (722 eyes) were included in this study. The mean age was 24.7 ± 6.5 years and the average maximal keratometry was 51 ± 5.2 D for the better eye and 58.4 ± 9.6 D for the worse eye. Upon diagnosis, 233 eyes (32.2 %) and 51 eyes (7.1 %) had a thinnest pachymetry <450 and <400 μm, respectively. At 6-month follow-up, 58 % of patients had been fitted with specialty contact lenses. During follow-up, 199 eyes (27.6 %) underwent corneal crosslinking. One patient underwent corneal graft surgery of his worse eye due to contact lens intolerance and insufficient visual acuity.ConclusionDespite advances in diagnostic tools, keratoconus is often diagnosed at a relatively late stage. Earlier detection of keratoconus would increase the overall clinical benefit of corneal crosslinking. Further research into screening strategies is required to develop cost-effective screening programs.     

Trans epithelial corneal collagen crosslinking for progressive keratoconus: 6 months follow up

PurposeTo evaluate keratoconus biomechanical changes after transepithelial corneal collagen cross linking (TE CXL) using riboflavin and ultraviolet A (UVA).SettingSecond University of Naples, Naples, Italy.DesignProspective non comparative case series study.MethodsPatients with progressive keratoconus were examined, before and during a 6 months follow up after TE CXL, with a Pentacam, an Ocular Response Analyzer and an IOLMaster.Best corrected visual acuity (BCVA), refraction, corneal thinnest point (CTP), keratometry readings at the keratoconus apex (K_max), axial eye length (AL), corneal volume (CV) anterior chamber volume (ACV), anterior chamber depth (ACD), corneal hysteresis (CH) and corneal resistance factor (CRF) were evaluated.ResultsThirty-six eyes of 36 patients with progressive keratoconus were analyzed. Six months after treatment there was a significant improvement in BCVA (p < 0.01), no significant changes in refraction (p = 0.57), CTP (p = 0.07), K_max (p = 0.88), AL (p = 0.07), CV (p = 0.38), ACV (p = 0.07), ACD (p = 0.7), CH (p = 0.1) and CRF (p = 0.3).ConclusionsAccording to our results TE CXL stabilizes most of the patients with progressive keratoconus, without affecting in negative way the corneal elasticity.     

Measure of keratoconus progression in patients with vernal keratoconjunctivitis using scanning slit topography

PurposeTo document topographic changes using Orbscan in patients with keratoconus and vernal keratoconjunctivitis over 1 year.Material and methodsRetrospective analysis of clinical and Orbscan data of 22 eyes of 11 patients with keratoconus and VKC with follow up over 1 year period was done. The parameters studied included patients demographics, clinical features, visual acuity, refraction and Orbscan IIz. The changes in various Orbscan parameters were studied over the 1-year period.ResultsMean age was 14 ± 4.1years. 20 eyes had clinical keratoconus, while 2 had forme fruste keratoconus. 8 eyes of 22 showed evident progression (>1 diopter change in mean simulated (sim) K over 12 months). There was no significant difference in the visual acuity or clinical features over follow up. In patients with progression, statistically significant change (p < 0.05) was found in posterior float curvature, sim K astigmatism and maximum astigmatism. Rest of the parameters did not show significant change. Among the patients without evident progression, none of the parameters showed significant change. On comparing the patients with clinical signs of keratoconus with those with only topographic signs of keratoconus, there was no difference between the two groups with respect to the rate of progression of keratoconus. Patients with both mixed type and pure palpebral type of VKC had comparable Orbscan parameters at baseline and 1 year follow up and similar progression rate of keratoconus.ConclusionSerial topographic analysis provides numerical information about various corneal parameters in patients with vernal keratoconjunctivitis and keratoconus.     

Progressive keratoconus in patients older than 48 years

PurposeTo report cases of progressive keratoconus (KC) in patients aged ≥48 years and the successful arrest of progression using corneal cross-linking (CXL) with riboflavin and ultraviolet-A light.ObservationsFive eyes from four patients with progressive KC aged 48, 48, 51 and 54 years are reported in this case series. All eyes were followed regularly after initial diagnosis. K_max was used as an indicator of progression and KC progressed at a rate of 1.4 diopters in 6 months and 14.6 diopters in 14 months. All patients eventually received CXL, and all were aged ≥50 years at the time of the procedure. One eye required two CXL procedures to successfully stabilize the patient’s cornea.ConclusionDespite the probability of KC progression strongly declining after the age of 40 years, it never becomes zero. It is therefore advisable to continue regular follow-up corneal tomography examinations in patients with KC, even in their fifth and sixth decades of life.     

Corneal cross-linking for Acanthamoeba keratitis in an orthokeratology patient after swimming in contaminated water

PurposeTo report a case of Acanthamoeba keratitis diagnosed using confocal microscopy in a patient corrected by orthokeratology and treated with corneal crosslinking (CXL) after failure to respond to medical treatment.MethodsAfter diagnosis, the patient was treated with several medications until CXL was applied during one 30-min session using ultraviolet A radiation and application of riboflavin. The clinical signs of the disease observed using slit-lamp biomicroscopy and confocal microscopy were evaluated and the visual acuity was measured during the course of the infection and treatment over a period of 30 months including 12 months of medical treatment, 9 months after cross-linking and amniotic membrane transplant and 9 months after penetrating keratoplasty and cataract extraction.ResultsIn this case, confocal microscopy facilitated early diagnosis of an Acanthamoeba infection even if other signs and symptoms might be confounding. CXL was more effective than aggressive medication against the microorganism. After CXL, the symptoms and the corneal appearance improved significantly but the ulcer did not heal completely. After amniotic membrane transplantation, the patient underwent penetrating keratoplasty (PK) with no rejection, and the visual function substantially improved over 9 months of follow-up.ConclusionsSwimming in contaminated water might represent a risk for orthokeratology patients. CXL was effective for treating Acanthamoeba keratitis in an orthokeratology patient to eliminate active and cystic forms of the microorganism. Confocal microscopy was useful to confirm the diagnosis in the presence of confounding clinical signs observed during a conventional slit-lamp examination. Both CXL and confocal microscopy are essential to the outcome of PK.     

Keratoconus presenting with bilateral simultaneous acute corneal hydrops

PurposeTo report a case of unknown keratoconus presenting with bilateral simultaneous acute corneal hydrops.MethodsCase report.ResultsA case of a 12-year-old male patient with Leber congenital amaurosis (LCA) presented with sudden whitening and lacrimation for 2 days in both eyes simultaneously. At the initial examination, there were bilateral acute corneal hydrops, enophthalmic eyes and roving nystagmus. Ultrasonography revealed clear crystalline lenses and attached retina. Initial management consisted of topical hypertonic solutions, steroids and artificial tears.ConclusionBilateral simultaneous acute corneal hydrops has not been reported before in the literature. It may be the presenting sign of keratoconus.     

Acute corneal hydrops: a case report including confocal and histopathological considerations.

This is a case report of corneal hydrops associated with keratoconus with a review of current literature pertaining to diagnosis, histopathology, and treatment options. A 30-year-old African American male presented to the University Eye Institute with acute unilateral pain, redness, and visual impairment. His symptoms, clinical presentation and past diagnosis of keratoconus confirmed his condition to be acute corneal hydrops (CH). The condition was closely followed utilizing topical treatment including hyper-osmotic (Muro 128) and non-steroidal anti-inflammatory agents (Acular and Voltaren). After 4 months, the patient's condition resolved but subsequent corneal scarring resulted. Corneal ectasia in patients with keratoconus may progress into acute rupture of the posterior limiting lamina (PLL) and the endothelium, resulting in CH, which may manifest as an area of edematous and opacified cornea lasting up to 4 months in duration. Acute complications such as CH seldom occur. Histopathology and confocal microscopy can be used to help visualize and understand CH on a cellular level. After regeneration of the corneal structures, central scarring may limit visual acuity and necessitate a corneal transplant.     

碳化二亚胺/羟基丁二酰亚胺交联改性胶原蛋白纤维制备及其性能

为解决由湿法纺丝工艺制备的牛肌腱胶原蛋白纤维力学性能差、遇水易溶解等问题,采用1-乙基-3-(3-二甲基丙基)碳化二亚胺盐酸盐/N-羟基丁二酰亚胺(EDC/NHS)对胶原蛋白纤维进行交联改性。探究了原位交联方式的最优交联时间和交联剂质量分数,并着重对比了原位交联与交联浴交联2种交联方式对胶原蛋白纤维性能的影响。结果表明:原位交联可显著改善胶原蛋白纤维的性能,最优的交联时间和交联剂质量分数分别为11 h、15%,此时纤维断裂强度可达1.44 cN/dtex左右,较纯胶原蛋白纤维提高了35.8%,较交联浴交联纤维提高了19.0%;与主要发生在纤维表面的交联浴交联相比,原位交联能够使纤维内部的微纤结构更加致密,性能得到更为显著的提升,由原位交联制备的胶原蛋白纤维性能优于交联浴交联制备的纤维。     

Longitudinal corneal tomographical changes in eyes of patients with unilateral and bilateral non-progressive keratoconus

AimTo evaluate the tomographic indices changes in keratoconic eyes which were classified as unilateral and bilateral non-progressive keratoconus according to the definition of Global Consensus on keratoconus and ectatic disease.MethodsFifty non-progressive fellow eyes of 50 keratoconus patients who underwent corneal cross-linking treatment for the other progressive eyes (group 1), 50 eyes of 50 keratoconus patients who were followed up as bilateral non-progressive keratoconus (group 2), and 50 eyes of 50 control subjects (group 3) were included in this retrospective study. Topographic, topometric, and Belin–Ambrósio Enhanced Ectasia Display-III indices were recorded at baseline and after six months.ResultsGroups were similar in terms of age and gender. The changes in topographic parameters and topometric indices were similar among the three groups (p > 0.05 for all values). The maximum pachymetric progression index (PPI_max), maximum Ambrósio relational thickness (ART_max), and final D significantly increased at sixth-months in group 1 (p < 0.001, p = 0.004, and p = 0.02 respectively) but did not change in groups 2 and 3 (p > 0.05 for all values). ART_max, PPI_max, and final D value changes indicated a statistically significant difference among the groups using the one-way ANOVA test (p = 0.03, p = 0.007, and p = 0.03 respectively). The Bonferroni posttest revealed that these values increased at a higher rate in group 1 than in group 2 (p = 0.03, p = 0.01, and p = 0.04 respectively) and group 3 (p = 0.04, p = 0.03, and p = 0.04, respectively).ConclusionsFellow eyes of keratoconus patients who have underwent CXL for their progressive eyes may be more prone to progress than the patients who have no progression in both eyes. Screening unilateral non-progressive patients more closely than those with bilateral non-progressive patients and evaluating the changes in final D, ART_max, and PPI_max values may be helpful in the follow up of non-progressive keratoconus.     

一种丙二酸衍生物的制备及其对胶原膜的改性应用

将丙二酸与N-羟基琥珀酰亚胺(NHS)在二环己基碳二亚胺(DCC)催化下反应得到丙二酸NHS酯。以丙二酸NHS酯为交联剂对胶原膜进行交联改性,考察不同交联剂浓度对胶原膜物理化学性能的影响,通过测试其变性温度、吸水率、酶解率和机械强度等,来表征交联前后膜性能的改变。结果表明:经过丙二酸NHS酯交联改性后的胶原膜热稳定性、形态稳定性增强,抵抗酶解的能力增加,机械强度有所提高。说明丙二酸NHS酯作为一种交联剂,可有效改善胶原膜的物理化学性能。     

The research progress on the molecular mechanism of corneal cross-linking in keratoconus treatment

Keratoconus (KC) is a corneal anomaly that is manifested in a limited cone-like bulge with corneal thinning. Many molecules in the cornea change during the development of KC, including various components of the extracellular matrix, cytokines, cell connection, and cell adhesion-related proteins. Several treatment options are available, with corneal cross-linking (CXL) being the treatment of choice for early KC. However, postoperative complications have been reported in some CXL patients, mainly caused by corneal epithelial resection. Despite the fact that some novel approaches have helped to reduce some of the initial post-operative issues, their effectiveness seems to be inferior to that of the original CXL. To keep effectiveness while avoiding these negative effects, it is necessary to study the mechanism of CXL in KC treatment at the molecular level. This article provides a review of the molecular mechanism of CXL in the treatment of KC from four aspects: enzyme activity, signal transduction pathway, corneal-related proteins, and other KC-related molecules, further confirming the feasibility of CXL treatment of KC, providing new ideas for improving CXL.     

Fluid filled scleral contact lens in pediatric patients: challenges and outcome

PurposeTo study the indications and the challenges while fitting scleral contact lens (ScCL) filled with fluid prior to lens insertion in pediatric patients.MethodsWe retrospectively reviewed charts of patients of 16 years or less who received ScCL (PROSE – Prosthetic Replacement of the Ocular Surface Ecosystem, Boston Foundation for Sight, Needham Heights, MA, USA) that were filled with fluid (Normal saline) before lens insertion during July 2006 to April 2010. The main goal of ScCL fitting was to improve vision in patients having keratoconus (KC) and improve the ocular microenvironment in ocular surface disease (OSD). Visual acuity before and after lens wear was noted.ResultsFluid-filled ScCL were dispensed to 15 patients (20 eyes). The indications for ScCL fitting were KC (n = 3 eyes), Stevens Johnson syndrome (SJS, n = 13 eyes), radiation keratopathy (n = 1 eye), combined KC and SJS (n = 1 eye) and KC and vernal keratoconjunctivitis (VKC, n = 2 eyes). Mean age of the patients was 12.85 years. The average daily lens wear was 9 h. The vision improved by 2 lines or more in 85% and dropped by 2 lines or more in 45% eyes after 4 h of lens wear due to tear debris collection. None of the patients had any complications. Patients were self sufficient inserting and removing ScCL. Two patients had broken lenses during the follow-up.ConclusionsScCL are useful for pediatric patients who have OSD, irregular astigmatism or the two coexisting; KC combined with VKC or SJS, helping to maintain the health of the ocular surface and improves vision in these patients.     

利用猪胶皮制作可食性胶元人造肠衣的研究

本文利用制革工业中的副产品猪胶皮研制可食性人造肠衣。经酸溶胀处理的猪胶皮破碎后可得到胶元蛋白糊状物,将固形物含量为4％左右的胶元蛋白糊状物均匀地涂布在支撑物上干燥后可得胶元蛋白膜。再用低于0.1％的乙二醛或戊二醛溶液对胶元蛋白膜进行交联处理或烟熏处理,可以提高膜的拉伸强度与热稳定性,经交联或烟熏处理后的胶元蛋白膜的超微结构发生了变化,碱性氨基酸含量下降,加热收缩率均低于25％,它具有与天然干肠衣相同的强度。     

Ultrasound biometry in the diagnosis of amblyopia in keratoconus.

Here, we describe a case in which A-scan ultrasound biometry was used to differentially diagnose the cause of reduced vision in a patient with keratoconus. A patient with keratoconus presented with reduced visual acuity in one eye, not improvable above 6/18 with specialist keratoconus contact lens fitting. This monocular amblyopia was attributed to previous anisometropic ametropia by the use of ultrasound biometry. The report demonstrates the usefulness of ultrasound biometry in the detection of amblyopia in circumstances in which a previous assessment of amblyopia is not possible. This information will impact upon decisions made for the future clinical management in this case, especially if vision deteriorates so that a corneal graft is required.     

Scleral contact lenses in the pediatric population—Indications and outcomes

PurposeTo report the use of a custom-designed, scleral contact lens (SL) in the treatment of pediatric patients.MethodsThe medical records of all patients under 15 years of age fitted with SL from March 2018 through February 2020 were retrospectively reviewed. Ophthalmic diagnosis, prior surgical intervention, lens wearing failures, and duration of lens use are reported.ResultsLenses were dispensed to 18 patients (24 eyes). Main indications for SL fitting were refractive error correction (n = 18: keratoconus (KCN), traumatic corneal scarring, corneal transplant status, and aphakia) and ocular surface protection and optimization (n = 6: neurotrophic keratitis and chronic blepharokeratoconjunctivitis). Patient age ranged from 16 months to 14 years (mean, 9.9 ± 3.5 years (mean ± standard deviation (SD)). Patients fitted for surface disease indications were significantly younger, 8.8 ± 2.5 years. The mean maximal keratometry reading in patients with keratoconus was 64.0 ± 12.6 diopters (D). In six eyes with advanced KCN (Kmax 71.8 ± 11.0 D) and three eyes with traumatic scarring, SL use obviated the need for keratoplasty. Fifteen patients (83 %) continued scleral lens wear with a mean follow-up period of 9.2 ± 7.4 months. Complications included one case of corneal graft rejection and one corneal abrasion associated with lens insertion.ConclusionsThe goals of SL fitting in pediatric patients are visual rehabilitation and ocular surface protection. Pediatric patients with advanced keratoconus and traumatic corneal scarring are most appreciative of the benefits of scleral lenses. The challenges associated with SL fitting and the training process did not preclude long-term SL wear.     

COLLAGEN CHARACTERISTICS OF PRONGHORN ANTELOPE AND SHEEP MUSCLE

Guanidine hydrochloride soluble intramuscular collagen (GSIC) obtained from purified longissimus intramuscular collagen of five yearling and five older doe antelope and from two lambs and two ewes varied with age but did not differ significantly (P < 0.05) between species. Gel-disc electrophoresis of denatured GSIC showed a lower percentage of α-chain and a higher percentage of β-component for antelope than for sheep. Total collagen content was lower in antelope than in sheep muscle. Therefore, the extreme tenderness in antelope muscle may result from a lack of intramuscular collagen rather than variation in collagen crosslinking.     

Acute corneal edema decades after penetrating keratoplasty for keratoconus in eyes wearing scleral contact lenses

PurposeTo report three cases of acute corneal edema occurring decades after penetrating keratoplasty (PK) for keratoconus in eyes wearing scleral contact lenses (ScCLs) with previously clear corneal grafts.MethodsRetrospective chart review of three ScCL wearers presenting for sudden onset pain and blurred vision. Data extracted included clinical presentation, year and reason for PK, ocular medications and comorbidities, contact lens wearing history, results of any ancillary testing available including corneal topography, anterior segment optical coherence tomography (OCT), and specular microscopy surrounding the event, treatment and outcomes of intervention. The number of PK eyes fit with ScCLs in the author’s practice was determined to estimate the prevalence of this event.ResultsThe three patients each had a longstanding PK for keratoconus performed between 33–35 years prior to presentation and recurrent ectasia. Each patient presented with an acute, painful eye and reduced vision either 3 days, 4 months or 9 years after refitting into ScCLs. Each eye had well demarcated focal microcystic epithelial and stromal edema within the graft and crossing the wound margin onto the host cornea. Although a definitive break or detachment of Descemet’s membrane was not visualized, the presentations suggest these were episodes of acute hydrops.ConclusionsLongstanding PKs with recurrent ectasia and acute focal edema suggestive of corneal hydrops is demonstrated in this case series of ScCL wearers. Although similar events have occurred as part of the natural history of post-PK corneas for keratoconus, the proximity of ScCL refitting to two of the events suggests some association.