Abnormal Rubbing and Keratectasia

The cellular responses of corneal fibroblasts to cyclic stretching loads

Mechanical signaling plays a crucial role in maintaining extracellular matrix (ECM) homeostasis in various structures. In this study, we investigated the responses of corneal fibroblasts to cyclic stretching loads using an in vitro cell culture system. Bovine corneal fibroblasts were cultured and subjected to equibiaxial cyclic strain of 15% for 72 h at a frequency of 0.25 Hz, with bovine skin fibroblasts used as a comparison. We explored various cellular behaviors, including morphological changes, cell proliferation, and metabolism in response to mechanical stretching loads. The expression of genes, protein secretion, and enzymatic activity for several major metalloproteinases was also determined through Q-PCR, Western blot, and gel zymography. Additionally, we investigated the involvement of mitogen-activated protein kinases (MAPKs) signaling pathways in the corneal fibroblasts when subjected to mechanical stimuli. Our findings revealed that, compared to skin fibroblasts, corneal fibroblasts were reluctant to morphological changes in response to a prolonged (72 h) and high-amplitude (15% of strain) cyclic stretching load. However, cyclic stretching loads stimulated the upregulation of MMP-2 expression in corneal fibroblasts via the MAPK signaling pathways involving extracellular signal-regulated kinase and p38. Together with a lack of upregulation in type I collagen expression, our results indicate the induction of the ECM degradation process in corneal fibroblasts in response to cyclic stretching. These findings emphasize the mechanoresponsive nature of corneal fibroblasts and shed light on the potential impact of intense mechanical stress on the cornea in both normal and pathological conditions such as keratoconus, providing valuable insights for understanding corneal mechanobiology.

Ocular surface inflammation and ectatic corneal disorders

PURPOSE OF REVIEW

Inflammatory mediators are a focus of recent corneal ectasia (CE) research and are a profound, modifiable contributor to CE in general and keratoconus (KC) in particular, opening a path to explore new methods of control. As advanced imaging technology and expanded population screening allow for earlier detection, the possibility of early intervention can profoundly change the prognosis of CE.

RECENT FINDINGS

Significant increases in the inflammatory mediators and immune components have been observed in the cornea, tear fluid, and blood of ectasia patients, while inflammation dampeners such as vitamin D and their receptors are reduced. Atopy and allergy have a strong association with KC, known to increase itch factors and stimulate eye rubbing, a risk factor in ectasia pathogenesis. Management of atopy or allergic conditions and topical anti-inflammatories has helped stabilize CE disease.

SUMMARY

Strategies such as monitoring inflammatory factors and using immune or inflammatory modulators, including managing subclinical inflammation, may be clinically beneficial in stabilizing the disease and improving outcomes. The detected factors are biomarkers, but as yet unproven to be sensitive or specific enough to be considered biomarkers for early detection of CE. The establishment of such biomarkers could improve the therapeutic outcome.

Non-canonical Wnt signaling in the eye

Wnt signaling comprises a group of complex signal transduction pathways that play critical roles in cell proliferation, differentiation, and apoptosis during development, as well as in stem cell maintenance and adult tissue homeostasis. Wnt pathways are classified into two major groups, canonical (β-catenin-dependent) or non-canonical (β-catenin-independent). Most previous studies in the eye have focused on canonical Wnt signaling, and the role of non-canonical signaling remains poorly understood. Additionally, the crosstalk between canonical and non-canonical Wnt signaling in the eye has hardly been explored. In this review, we present an overview of available data on ocular non-canonical Wnt signaling, including developmental and functional aspects in different eye compartments. We also discuss important changes of this signaling in various ocular conditions, such as keratoconus, aniridia-related keratopathy, diabetes, age-related macular degeneration, optic nerve damage, pathological angiogenesis, and abnormalities in the trabecular meshwork and conjunctival cells, and limbal stem cell deficiency.

Possible association of keratoconus progression with gender-affirming hormone therapy: A case report

Purpose

To present a case of keratoconus progression following gender-affirming hormone therapy.

Observations

A 28-year-old male-to-female transgender patient with potential past ocular history of subclinical keratoconus presented with subacute worsening myopia of both eyes (OU), 4 months after initiation of gender-affirming hormone therapy. A diagnosis of keratoconus was established based on slit-lamp exam and computerized corneal tomography. Notable indices were central corneal thinning and inferior steepening OU with maximum corneal curvatures of 58.3 D of the right eye (OD) and 77.7 D of the left eye (OS) and thinnest corneal thickness of 440 μm OD and 397 μm OS. After 8 months of continued hormone therapy, the patient's keratoconus continued to progress and thus corneal crosslinking was recommended and performed.

Conclusions

Keratoconus progression and relapse has been suggested to have an association with sex hormone changes. We report a case of keratoconus progression following gender-affirming hormone therapy in a transgender patient. Our findings continue to support a correlative relationship between sex hormones and corneal ectasia pathophysiology. Further studies are needed to determine causality and to investigate the utility of screening corneal structure prior to the initiation of gender-affirming hormone therapies.

Meta-Analysis of Keratoconus Transcriptomic Data Revealed Altered RNA Editing Levels Impacting Keratin Genomic Clusters

Introduction

Keratoconus (KC) is an ocular disorder with a multifactorial origin. Transcriptomic analyses (RNA-seq) revealed deregulations of coding (mRNA) and non-coding RNAs (ncRNAs) in KC, suggesting that mRNA-ncRNA co-regulations can promote the onset of KC. The present study investigates the modulation of RNA editing mediated by the adenosine deaminase acting on dsRNA (ADAR) enzyme in KC.

Materials

The level of ADAR-mediated RNA editing in KC and healthy corneas were determined by two indexes in two different sequencing datasets. REDIportal was used to localize known editing sites, whereas new putative sites were de novo identified in the most extended dataset only and their possible impact was evaluated. Western Blot analysis was used to measure the level of ADAR1 in the cornea from independent samples.

Results

KC was characterized by a statistically significant lower RNA-editing level compared to controls, resulting in a lower editing frequency, and less edited bases. The distribution of the editing sites along the human genome showed considerable differences between groups, particularly relevant in the chromosome 12 regions encoding for Keratin type II cluster. A total of 32 recoding sites were characterized, 17 representing novel sites. JUP, KRT17, KRT76, and KRT79 were edited with higher frequencies in KC than in controls, whereas BLCAP, COG3, KRT1, KRT75, and RRNAD1 were less edited. Both gene expression and protein levels of ADAR1 appeared not regulated between diseased and controls.

Conclusions

Our findings demonstrated an altered RNA-editing in KC possibly linked to the peculiar cellular conditions. The functional implications should be further investigated.

TFOS Lifestyle: Impact of lifestyle challenges on the ocular surface

Many factors in the domains of mental, physical, and social health have been associated with various ocular surface diseases, with most of the focus centered on aspects of dry eye disease (DED). Regarding mental health factors, several cross-sectional studies have noted associations between depression and anxiety, and medications used to treat these disorders, and DED symptoms. Sleep disorders (both involving quality and quantity of sleep) have also been associated with DED symptoms. Under the domain of physical health, several factors have been linked to meibomian gland abnormalities, including obesity and face mask wear. Cross-sectional studies have also linked chronic pain conditions, specifically migraine, chronic pain syndrome and fibromyalgia, to DED, principally focusing on DED symptoms. A systematic review and meta-analysis reviewed available data and concluded that various chronic pain conditions increased the risk of DED (variably defined), with odds ratios ranging from 1.60 to 2.16. However, heterogeneity was noted, highlighting the need for additional studies examining the impact of chronic pain on DED signs and subtype (evaporative versus aqueous deficient). With respect to societal factors, tobacco use has been most closely linked to tear instability, cocaine to decreased corneal sensitivity, and alcohol to tear film disturbances and DED symptoms.

Independent and interactive effects of eye rubbing and atopy on keratoconus

Purpose

To evaluate the independent and interactive effects of eye rubbing and atopy on keratoconus (KC) in central China.

Methods

A total of 330 KC patients and 330 controls were recruited in the case-control study. Eye rubbing and history of atopy were recorded through face-to-face interviews. The association between KC and eye rubbing, atopy, interactive effects of eye rubbing and atopy were analyzed by logistic regression, and the odds ratios (OR), relative excess risk due to interaction (RERI), attributable proportion (AP), synergy (S) index, and 95% confidence intervals (95% CI) were calculated.

Results

A total of 228 patients (69.09%) had an eye rubbing history, and 53 (16.06%) had an atopy history in the KC group, which were both higher than that in the control group (p<0.001). Eye rubbing and atopy were positively associated with KC in multivariate analysis, with ORs (95% CIs) of 15.11 (10.02, 22.80) and 5.30 (2.59, 10.84), respectively. Compared to non-eye rubbing and non-atopy eyes, the risk for eye rubbing coexisted with atopy was 52.31 (12.25, 223.35). No significant associations were found between KC and multiplicative interaction (p=0.608). The RERI, AP, and S values were 32.89 (-43.35, 109.14), 0.63 (0.05, 1.21), and 2.79 (0.56, 13.96), respectively, with no significant association between additive interaction and KC. No significant associations were found between eye rubbing, atopy and the severity of KC (p>0.05).

Conclusion

Eye rubbing and atopy were separately positively associated with KC, and there was a strong impact of coexistent eye rubbing and atopy on KC in China. Further multi-center and cohort study need to be conducted to explore the role of eye rubbing and atopy in the occurrence and development of KC.

Small Incision Lenticule Extraction (SMILE) for the Correction of High Myopia With Astigmatism

PURPOSE

To report the outcomes of small incision lenticule extraction (SMILE) for high myopia between -9.00 and -14.00 diopters (D).

METHODS

This was a prospective study of SMILE for high myopia using the VisuMax femtosecond laser (Carl Zeiss Meditec). Inclusion criteria were attempted spherical equivalent refraction (SEQ) between -9.00 and -14.00 D, cylinder up to 7.00 D, corrected distance visual acuity (CDVA) of 20/40 or better, age 21 years or older, and suitable for SMILE. The sub-lenticule thickness was 220 µm or greater, and the total uncut stromal thickness was 300 µm or greater. Patients were to be followed up for 1 year. Standard outcomes analysis was performed using 12-month data where available or 3-month data otherwise.

RESULTS

Of 187 eyes treated, data were available at 12 months for 181 eyes (96.8%) and 3 months for 4 eyes (2.1%), and 2 eyes (1.1%) were lost to follow-up. Mean attempted SEQ was -10.55 ± 1.00 D (range: -9.00 to -12.99 D). Mean cylinder was -1.19 ± 0.83 D (range: 0.00 to -4.00 D). Preoperative CDVA was 20/20 or better in 73% of eyes. Postoperative uncorrected distance visual acuity was 20/20 or better in 57% and 20/25 or better in 82% of eyes. Mean SEQ relative to target was -0.22 ± 0.48 D (range: -1.63 to +1.38 D), 66% ± 0.50 D and 93% ±1.00 D. Mean SEQ 12-month change was -0.08 ± 0.34 D (range: -1.75 to +0.88 D). There was loss of one line of CDVA in 4% of eyes, and no eyes lost two or more lines. Contrast sensitivity was unchanged. Patient satisfaction was 8 or more out of 10 in 94% and 6 or more in 99% of patients.

CONCLUSIONS

Outcomes of SMILE for myopia greater than -9.00 D at 3 to 12 months showed excellent efficacy, safety, stability, and predictability, with high patient satisfaction. [J Refract Surg. 2022;38(5):262-271.].

Results of Follow-up in Pediatric Keratoconus Treated With Intracorneal Ring Segments Implantation Alone or in Combination With Corneal Cross-linking

PURPOSE

To report visual and topographic outcomes of pediatric keratoconus with intracorneal ring segments (ICRS) implantation alone or in combination with accelerated corneal cross-linking (A-CXL).

METHODS

A descriptive, retrospective observational study was performed. Medical records of patients younger than 18 years at Fundación Oftalmológica Nacional in Bogotá, Colombia, were reviewed. Demographic data, follow-up time, preoperative and postoperative uncorrected (UCVA) and best corrected (BCVA) visual acuity, manifest refraction, and tomography were evaluated. SPSS software (version 22.0; SPSS, Inc) was used for analysis.

RESULTS

Twenty-six eyes of 19 patients with a mean age of 16.5 ± 1.8 years were analyzed, and 16 were boys (84.2%). Median follow-up time was 39.6 months (inter-quartile range [IQR] = 30). Fifteen patients (78.9%) had a history of allergic conjunctivitis. Sixteen eyes (61.5%) received ICRS implantation with A-CXL and 10 eyes (38.4%) received ICRS implantation only. Global results (including ICRS implantation with A-CXL and ICRS implantation only) were: (1) median UCVA of 0.90 logarithm of the minimum angle of resolution (logMAR) (IQR = 0.85) preoperatively improved to 0.54 logMAR (IQR = 0.70) postoperatively; (2) median BCVA of 0.43 logMAR (IQR = 0.39) preoperatively improved to 0.30 logMAR (IQR = 0.26) postoperatively; and (3) median spherical equivalent of -5.37 diopters (D) (IQR = -5.28) preoperatively improved to -4.12 D (IQR = -3.57) postoperatively. There was a reduction in half of the sphere and cylinder. The median maximum keratometry was 54.40 D (IQR = 7.4) preoperatively and 49.80 D (IQR = 5.3) postoperatively. The median asphericity was -1.18 (IQR = 0.70) preoperatively and changed to -0.75 (IQR = 0.68) postoperatively. No patient presented with complications before or after surgery.

CONCLUSIONS

ICRS implantation only or in combination with A-CXL induced visual and topographic improvement in patients with keratoconus, which was maintained throughout the follow-up time. It seems to be a safe procedure to delay or avoid corneal transplantation in the pediatric population. [J Pediatr Ophthalmol Strabismus. 2022;59(2):118-127.].

Distribution pattern of total corneal thickness in keratoconus versus normal eyes using an optical coherence tomography

Purpose:

To evaluate the total corneal thickness distribution pattern using a high-resolution spectral-domain optical coherence tomography (HR SD-OCT) for distinguishing normal eyes from keratoconus (KCN).

Methods:

One hundred and forty-four patients were enrolled in three groups (55 normal, 45 mild KCN, and 44 moderate-to-severe KCN eyes) in this prospective diagnostic test study. Total corneal thickness was measured in 8 semi-meridians using HR SD-OCT (Heidelberg Engineering, Heidelberg, Germany) in 5 and 7 mm zones. The central corneal thickness (CCT), corneal focal thinning (minimum thickness [Min], min minus median and maximum [Min-Med, Min-Max]), and asymmetry indices (inferior minus superior [I-S] and supranasal minus infratemporal [SN-IT]) were calculated. One-way analysis of variance and the area under the receiver operating characteristic curve (AUC) were used for the analysis.

Results:

Thinner CCT, lower Min thickness, more negative Min-Max, Min-Med, and greater I-S and SN-IT were found in KCN eyes compared to the control group (P < 0.001). The inferior and IT semi-meridians were the thinnest locations in KCN cases in the 5 mm central zone (P < 0.001). CCT followed by Min-Med had the highest discriminative ability for differentiating mild KCN (AUC, sensitivity and specificity: 0.822, 87.0%, 60.37% and 0.805, 82.93%, 66.0%, respectively) and moderate-to-severe KCN (0.902, 87.82%, 73.08% and 0.892, 85.37%, and 78.85%, respectively) from normal corneas.

Conclusion:

The inferior and IT sectors of the cornea with the largest thickness changes in the 5 mm zone are the most common thinning sites in keratoconic corneas, and CCT and Min-Med are the most sensitive indices for the diagnosis of KCN.

Corneal Scheimpflug topography values to distinguish between normal eyes, ocular allergy, and keratoconus in children

To identify and compare keratometric, corneal thickness, and elevation parameters and indices among healthy children, ocular allergy, and keratoconus using the OCULUS Pentacam Scheimpflug topography system. This study included healthy children, children with ocular allergy (OA) without keratoconus, and children with keratoconus (KC). The study design consisted of a prospective evaluation and review of medical records from a Brazilian ophthalmology department. The exclusion criteria were inability to undergo the ocular exam, other ocular diseases, contact lens wear, and topographic corneal ectasia. The effect of each corneal parameter was evaluated using univariate and multivariate logistic regression models adjusted for sex and age, and ROC curves were used to assess the ability each variable to discriminate among groups. A total of 182 subjects were included: healthy children (n = 99), children with OA (n = 32), and children with KC (n = 51). Groups differed in terms of sex, with more males in the OA group (73.2%) and the KC group (67.7%) than in the control group (40.9%). All corneal parameters studied differed significantly between the control and KC groups, and between the OA and KC groups; they also differed significantly between the three groups in terms of astigmatism, q-value, CCT, TP, BAD-D, and ARTmax values. We present the first study to describe and compare corneal tomographic parameters in healthy children, OA, and KC. Keratometry indices, ACD, ARTmax, AETP, and PETP were found to be the most useful for differentiating between healthy and KC children.IBR registry number: CAAE 54921916.9.0000.5404.

Association Between Keratoconus and Shoulder Dislocation: A Cross-Sectional Study

Introduction Few studies have highlighted the correlation between shoulder dislocation and keratoconus (KC). This study aimed to examine the association between KC and shoulder dislocation using patients with KC and matched controls. Methods This cross-sectional study was conducted at Jordan University Hospital. We included patients diagnosed with KC from Jordan University Hospital's Ophthalmology Department between 2015 and 2018. We also included age- and sex-matched controls recruited randomly from fitness centers and shopping malls. All participants had complete ophthalmic and orthopedic assessments. KC was diagnosed by clinical examination followed by Pentacam (Scheimpflug Images, Oculyzer, WaveLight, Alcon, USA) confirmation. Results A total of 238 patients, with a mean age of 29.53 (±11.20) years, were included in this study. They were 144 (60.5%) men and 94 (39.5%) women. Moreover, 120 (50.4%) had KC while 118 (49.6%) did not have KC. Only 11 (4.6%) patients had previous shoulder dislocation. We did not find a significant difference in the frequency of shoulder dislocation between patients with and without KC (p = 0.512). Conclusion This study provides further evidence on the lack of association between shoulder dislocation and KC, an association that was presumed due to shared collagen characteristics.

Five-Year Long-Term Results of Standard Collagen Cross-Linking Therapy in Patients with Keratoconus

Objectives:

We aimed to demonstrate the 5-year visual, topographic, and aberrometry long-term results of standard collagen cross-linking (CCL) treatment in keratoconus patients.

Materials and Methods:

The files and topographic measurements of patients who underwent standard CCL treatment for progressive keratoconus were retrospectively reviewed. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refraction values, and topographic values were evaluated.

Results:

Thirty-seven eyes of 27 patients were included in the study. The female to male ratio was 15 (56%)/12 (44%) and the mean age was 22.16±6.4 (12-39) years. The increase in UCVA and BCVA was statistically significant at postoperative 1-5 years (all p values <0.05). The changes in the spherical equivalent after CCL were not statistically significant (p>0.05), but the decrease in the manifest astigmatism values were significant after CCL at 3-5 years (p<0.05). Decrease in K2 (steep keratometry) and K apex values were statistically significant at 1-5 years (p<0.05). There was a significant decrease in the thinnest corneal thickness compared to the preoperative values up to 6 months and 1-4 years (p<0.05), but the change at 5 years was not significant (p=0.08). Post-CCL reductions in high-order aberrations and spherical aberrations were significant at postoperative 5 years and 3-5 years (p<0.05).

Conclusion:

In long-term follow-up, CCL treatment is seen to arrest keratoconus progression, increase vision, and improve visual quality by reducing higher-order aberrations and spherical aberrations. For these reasons, CCL treatment continues to be the first treatment modality in patients with progressive keratoconus.

Estimated Prevalence of Keratoconus in the United States From a Large Vision Insurance Database

PURPOSE

To estimate the prevalence of keratoconus in the United States using a large vision insurance database.

METHODS

We used data from the 2016 vision service plan (VSP) Global claims database to estimate the prevalence of keratoconus among enrollees by state. The VSP Global database includes cross-sectional de-identified claims data summarized by state of residence in predefined age and gender groups. Crude values of prevalence of keratoconus are provided in the VSP Global database. The open-source software package qGIS version 3.12 was used as the geographic information system for geospatial analysis.

RESULTS

The prevalence of keratoconus among VSP enrollees in the United States was estimated to be 0.15% with 95% confidence interval (CI) (0.15%, 0.15%). The prevalence of keratoconus was highest in Western states and among male population. The highest prevalence of keratoconus was in Colorado (0.51%; 95% CI 0.49%-0.52%), with particularly high prevalence for men in the age groups 18 to 39 years (0.90%; 95% CI 0.84%-0.95%) and 40 to 64 years (0.90%; 95% CI 0.85%-0.95%).

CONCLUSION

The average prevalence of keratoconus in the United States in 2016 may be higher than previously reported. Living in Western states and male sex were associated with high prevalence.

Clinical evaluation of meibomian gland dysfunction in patients with keratoconus

PURPOSE

To investigate the association of keratoconus (KC) with meibomian gland dysfunction (MGD) and to describe the epidemiological characteristics of MGD in this disease.

METHODS

In this observational study, 120 KC patients seen in the Department of Ophthalmology of the Complexo Hospitalario Universitario de Santiago de Compostela and 87 controls were analyzed. The Ocular surface disease index (OSDI) questionnaire was administered and several DED tests and an evaluation of the meibomian glands and lid margin were performed. MGD signs and DED tests were compared between the groups. Symptoms were further analyzed in patients and controls with and without MGD.

RESULTS

KC was significantly associated with MGD after adjusting for age and sex [adjusted odds ratio (ORa), 2.40]. The frequency of MGD in KC patients [59 (49.2%) KC patients and 25 (28.7%) controls had MGD] correlated with the severity of KC (r = 0.206) (P = 0.020). Mean OSDI score in KC patients with and without MGD was 31.1 ± 24.1 and 35.2 ± 26.0 (P = 0.326), and 17.2 ± 22.7 and 13.3 ± 14.1 in controls with and without it (P = 0.366). The most common MGD signs coincided in both groups. Staining with fluorescein (P = 0.000) and lissamine green (P = 0.019) was higher in KC patients, but no differences were detected with TBUT (P = 0.116) or the Schirmer test (P = 0.637). Hypersecretory MGD was the most prevalent variant in both groups.

CONCLUSIONS

MGD and DED are common in KC patients. MGD correlates with the severity of KC and is indistinguishable from MGD in patients without KC. No association was found with symptoms. Patients with KC should be screened for MGD because of its possible clinical implications. Further research is needed to clarify the role of MGD in KC patients.

The role of environment in the pathogenesis of keratoconus

PURPOSE OF REVIEW

This study was conducted to demonstrate the importance of the environment in keratoconus (KC) genesis.

RECENT FINDINGS

Genetic-related connective tissue disorders demonstrate the inconsistency of theories regarding KC pathogenesis since no corneal steepening was observed in the majority of these patients. Despite recent advances and decades of research into the genetics of KC, the identification of disease-causing KC genes has been frustrating. Variants found based on genome-wide and next-generation sequencing only seem to account for a small number of cases or play a limited role in KC pathogenesis.

SUMMARY

The literature shows that mechanical manipulation may be the common underlying factor or the indispensable act precipitating the cascade of events leading to permanent corneal deformation. Hence, ophthalmologists have the opportunity to increase patient awareness about eye manipulation repercussions and treatment for ocular surface disorders.

VIDEO ABSTRACT

http://links.lww.com/COOP/A42.

A Case-Cohort Study of Exfoliation Risk Factors and Literature Review

The purpose of the study is to evaluate the risk factors associated with exfoliation in a case-cohort setting and literature review. This single-center, prospective, case-cohort study was carried out from January 2010 to April 2020 on patients operated for cataract surgery by a single surgeon in Lebanon. Forty-nine consecutive patients with exfoliation syndrome (XFS) and 62 consecutive control patients were identified and further investigated for selected systemic (diabetes mellitus, systemic hypertension, asthma, or atopy) and ocular variables (baseline vision, severity of nuclear sclerosis, glaucoma, eye rubbing, history of dry eye, or allergic eye disease). The mean baseline Snellen visual acuity was 20/283 in XFS versus 20/145 in control cases (P = 0.012). XFS also demonstrated significantly denser nuclear sclerosis than controls (P = 0.00958). By univariate analysis, allergic conjunctivitis (15 [30.6%] vs. 2 [3.2%]; P < 0.001), dry eye (20 [40.8%] vs. 13 [21.0%]; P = 0.0133), and habitual rubbing of the eyes (33 [67.3%] vs. 19 [30.6%]; P < 0.001) were associated with the presence of XFS. Habitual ocular rubbing was closely associated with allergic conjunctivitis (odds ratio [OR] = 13.0; 95% confidence interval [CI]: 2.8–58.8; P = 0.032). After multivariable analysis, the following variables showed significant results: glaucoma (OR = 34.5; 95% CI: 4.4–250; P = 0.010), duration of surgery (OR = 5.6; 95% CI 2.43–12.9; P < 0.001), and habitual ocular rubbing (OR = 4.42; 95% CI: 1.97–9.90; P = 0.029). This study shows a novel potential correlation between eye rubbing and XFS in a Lebanese cohort. Chronic eye rubbing induces or may exacerbate preexistent zonular damage in subjects with XFS, hence the need to better manage concurrent ocular surface disorder in these patients.

Keratoconus in a child with partial trisomy 13

Background: Clinical studies suggest the importance of genetic components in the etiology of keratoconus. However, the contributing genes and variants remain elusive. We present a case of bilateral keratoconus in a child with partial trisomy 13, with a trisomic region spanning loci that have been associated with keratoconus.Materials and Methods: This is a single, retrospective case report of a child with a molecular diagnosis of partial trisomy 13, who was diagnosed with bilateral keratoconus for which at the age of 11 years, she underwent successive epithelium-off corneal cross-linking (CXL) procedures in both eyes, followed by temporary central tarsorrhaphy under general anesthesia.Results: Patient's molecular diagnosis was 70 Megabase trisomic region 13q14.11q34. Pre CXL pachymetry was 426 μm and 496 μm, maximum K values were 52.28 D and 55.45 D in right and left eyes, respectively; at last follow up (12 months post-op) these were 494 μm and 509 μm for pachymetry and maximum K values 50.50 D and 52.43 D in the right and left eyes, respectively. No signs of progression were detected.Conclusion: To the best of our knowledge, this is the first case report to document bilateral keratoconus in a child with partial trisomy 13, in whom successful epithelium-off CXL was achieved with general anesthesia. We emphasize the importance of screening, early diagnosis, and therapy of this treatable but rare cause of decreased vision in partial trisomy 13 patients.

Eye rubbing in the aetiology of keratoconus: a systematic review and meta-analysis

PURPOSE

Keratoconus is a potentially blinding condition that slowly deforms the cornea in young people. Despite the increasing prevalence of keratoconus, the exact aetiology of the condition is unknown. This first systematic review examines the evidence of eye rubbing and its association with keratoconus and presents the findings of the meta-analysis.

METHODS

Two independent reviewers searched the electronic databases for all potential articles published from 1st of January 1900 to 31st of July 2020 on eye rubbing and keratoconus. The researchers assessed the methodological quality of the studies using the Newcastle-Ottawa scale for observational studies. The assessment for statistical heterogeneity was estimated using chi-square and I-square (I²) tests. A p value of < 0.05 was considered as statistically significant and I² < 30% as homogenous. Begg funnel plot was used to interpret the asymmetry or small study effects.

RESULTS

Eight case-control studies were included in this systematic review. Two studies assessed eye rubbing without odds ratios and thus were excluded. The pooled odds ratios for the six remaining studies included in the meta-analysis was 6.46 (95% CI 4.12-10.1). The study results were heterogenous (I² = 71.69 [95% CI 35.14-87.88]). All the studies scored moderate quality methodology on the Newcastle-Ottawa scale. Begg funnel plot showed asymmetry supporting heterogeneity.

CONCLUSION

Eye rubbing showed consistent association with keratoconus. However, the current evidence is limited to only a small number of case-control studies which present as heterogeneous and of sub-optimal methodological quality. Additionally, the cause-effect temporal relationship cannot be determined. Further studies are needed to address this intricate relationship of eye rubbing and its induction, ongoing progression, and severity of keratoconus.

[Explantation of the CyPass implant in a case series of patients with corneal decompensation]

BACKGROUND

In microinvasive glaucoma surgery (MIGS) the CyPass microstent (Alcon Inc.) was implanted in the suprachoroidal space to increase the uveoscleral outflow, thereby lowering the intraocular pressure. Due to the excessive loss of corneal endothelial cells, the implant was withdrawn from the global market in August 2018.

METHODS

A loss of corneal endothelial cells was observed in 6 patients (8 eyes in total) with early to moderate primary open-angle glaucoma 3 years after CyPass implantation. One eye developed a bullous keratopathy. In all patients an implant migration in the anterior chamber compared to the original postoperative position was detected, with more than one ring of the CyPass implant being visible in the anterior chamber.

RESULTS

In all eight cases the CyPass implant was removed. The local therapy with cortisone eye drops in combination with a 5% sodium chloride solution did not improve chronic corneal edema in one patient. Therefore, a Descemet membrane endothelial keratoplasty (DMEK) was performed with postoperative improvement of visual acuity.

CONCLUSION

In patients with more than one visible ring of the CyPass implant in the anterior chamber and subsequent localized loss of corneal endothelial cells, CyPass trimming or removal is recommended to avoid the progression of generalized corneal endothelial cell reduction and the onset of refractory, chronic corneal edema.

Evaluating Retinal and Choroidal Perfusion Changes After Ocular Massage of Healthy Eyes Using Optical Coherence Tomography Angiography

Background and objectives: Ocular massage (OM) is used as a treatment option for acute retinal artery occlusion, under the assumption that it induces vessel dilatation and enhances perfusion. Since evidence of ocular perfusion alteration due to OM is lacking, we investigate the impact of OM on the hemodynamics of the posterior pole in healthy eyes in a noninvasive fashion by using optical coherence tomography angiography (OCTA). Materials and Methods: A prospective study was conducted on healthy volunteers, each of whom underwent measurements of intraocular pressure (IOP), central macular thickness (CMT), subfoveal choroidal thickness (SFCT), radial peripapillary capillary perfusion (RPCP), superficial capillary plexus perfusion (SCPP), deep capillary plexus perfusion (DCPP), choriocapillaris perfusion (CCP), Sattler’s layer perfusion (SLP) and Haller’s layer perfusion (HLP) before and after OM. OM was performed for 2 min, consisting of 10-s turns of compression and decompression of the globe. Results: A total of 21 eyes from 21 participants (median age 29) were included. After OM, IOP significantly declined (p < 0.001), while SFCT (p < 0.005), SCPP (p < 0.001), DCPP (p = 0.004) and CCP (p = 0.008) significantly increased. CMT, RPCP, SLP and HLP did not show any significant alteration due to OM. Changes in SCPP correlated positively with changes in CCP and vice versa. Conclusions: OCTA-based analysis in healthy adults following OM demonstrated a significant increase of retinal perfusion values, assumed to be due to failure of autoregulatory mechanisms. These findings may indicate a positive effect of OM as a treatment option for patients with acute retinal artery occlusion.

The Prevalence and Risk Factors for Keratoconus: A Systematic Review and Meta-Analysis

PURPOSE

This study was conducted to determine the prevalence and risk factors for keratoconus worldwide.

METHODS

In this meta-analysis, using a structured search strategy from 2 sources, 4 electronic databases (PubMed, Web of Science, Google Scholar, and Scopus) and the reference lists of the selected articles were searched from inception to June 2018 with no restrictions and filters. The outcome of the study was the prevalence of keratoconus and its risk factors, including eye rubbing, family history of keratoconus, atopy, allergy, asthma, eczema, diabetes type I and type II, and sex.

RESULTS

In this study, 3996 articles were retrieved, of which 29 were analyzed. These 29 articles included 7,158,241 participants from 15 countries. The prevalence of keratoconus in the whole population was 1.38 per 1000 population [95% confidence interval (CI): 1.14-1.62 per 1000]. The prevalence of keratoconus was 20.6 per 1000 (95% CI: 11.68-28.44 per 1000) in men and 18.33 per 1000 (95% CI: 8.66-28.00 per 1000) in women in studies reporting sex. The odds ratio of eye rubbing, family history of keratoconus, allergy, asthma, and eczema was 3.09 (95% CI: 2.17-4.00), 6.42 (95% CI: 2.59-10.24), 1.42 (95% CI: 1.06-1.79), 1.94 (95% CI: 1.30-2.58), and 2.95 (95% CI: 1.30-4.59), respectively.

CONCLUSIONS

The results of this study, as the most comprehensive meta-analysis of keratoconus prevalence and risk factors, showed that keratoconus had a low prevalence in the world and eye rubbing, family history of keratoconus, allergy, asthma, and eczema were the most important risk factors for keratoconus according to the available evidence.

Genetics vs chronic corneal mechanical trauma in the etiology of keratoconus

Both genetic and environmental factors have been considered to play a role in the etiology keratoconus. Eye rubbing, and more recently eye compression due to sleeping position, have been identified to be highly related to the condition, and are present in a high percentage of patients. Today, the predominant model is that these factors can provide the "second hit" necessary to generate the condition in a genetically susceptible individual. In addition, the extremely high prevalence in Arab populations, where endogamy could play a role, the high concordance rate in monozygotic twins, and the presence of family history of the condition between 5 and 23% of cases, support a genetic influence. Segregation analysis studies suggest that keratoconus is a complex non-Mendelian disease. Results from linkage analysis, next generation sequencing studies and genome-wide association studies also have suggested that genetic factors are involved in the condition. Recently, it has been proposed that mechanical trauma (i.e. eye rubbing or eye compression at night), is a sine quanon condition for the onset of keratoconus, and quite possibly its only cause. There are various arguments for and against this hypothesis. Indeed, it is possible, as initially suggested around 55 years ago, that the term "keratoconus" include diverse phenotypically similar conditions, which are actually of different etiology.

Effect of rigid gas permeable contact lens on keratoconus progression: a review

The prevalence of keratoconus is 1/2000 in the general population and is high in adolescents. Keratoconus is a progressive disease, which has a great impact on patients' quality of life and mental health. It can be managed by surgical and non-surgical means, rigid gas permeable (RGP) contact lens as its main non-surgical method is widely used in clinic. The efficacy of wearing RGP contact lens has been confirmed to some extent, but some studies have found that wearing RGP contact lens has adverse effects, which may promote disease progression. In this paper, the advantages and disadvantages of RGP contact lens in controlling keratoconus were reviewed to provide more suggestions and references for the clinical application of RGP contact lens.

[Refractive surgery for children with developmental delay : Indications, techniques and results]

Visual stimulation and communication with the surroundings are crucial factors for childhood development. In children with intellectual disability the developmental delay can be exacerbated by visual impairment leading to visual autism. Uncorrected refractive error is one of the leading causes of visual impairment and spectacles are the gold standard for treatment. For some children with developmental delay or intellectual disability, the fitting and wearing of spectacles can be impossible due to severe craniofacial malformations, poor neck control or involuntary head movements. In these cases, if wearing contact lenses is also impossible the refractive error remains untreated and the child visually impaired. In certain situations cornea-based laser refractive surgery or lens-based refractive surgery can treat these refractive errors to enable better unaided visual acuity and therefore enhanced stimulation and integration of these developmentally delayed children. This article describes and discusses the indications, technical aspects and results of refractive surgery for children with developmental delay and intellectual disability.

Familial association of keratoconus and granular corneal dystrophy: The familial case series

OBJECTIVE:

The aim of the present study was to evaluate the coexistence of bilateral keratoconus and granular corneal dystrophy (GCD) in the members of a family.

METHODS:

A total of 22 patients were examined in four generations of the family tree in this family screening study. Visual acuity test, biomicroscopic examination, and fundus examination were performed in all patients. The diagnosis of granular dystrophy was based on biomicroscopic examination findings. Corneal topography was performed on the patients diagnosed with granular dystrophy and other family members aged >5 years with normal examination findings. Corneal photographs were obtained from all patients with granular dystrophy except one case.

RESULTS:

Keratoconus or subclinical keratoconus was detected in seven cases. In addition, GCD type 1 was found in six of the seven cases. All patients diagnosed with keratoconus and granular dystrophy were females. On the other hand, there was no ophthalmologic problem in the men of the family tree. Although an autosomal dominant inheritance was found, the onset of the disease only in women suggests that there may be a variant expression.

CONCLUSION:

The present study showed an association of GCD and keratoconus in four generations of a family. More research is required to further explain this association.

Noncontact Meibography in Patients with Keratoconus

Purpose

To examine the morphological changes in the meibomian glands of patients with keratoconus as well as to study the relationship between these changes in the morphology and several tear film parameters.

Methods

Examination of the meibomian gland (MG) of 300 keratoconus patients presenting to the center using infrared noncontact meibography system (Sirius, CSO, Italy) between January 2017—January 2019. 100 eyes of healthy individuals were also enrolled as a control group. Tear breakup time (TBUT) test and Schirmer test II were evaluated. Subjective symptoms were also assessed using Ocular Surface Disease Index (OSDI).

Results

Mean age of keratoconus patients was 19 ± 12 years and 21 ± 14 years in control group. Average TBUT was 4.9 ± 2.1 sec. and average Schirmer test was 5.3 ± 2.2 mm which was significantly lower than control group (p=0.05). Meibomian gland dropout in the lower eyelid of the keratoconus group was as follows: grade 0 (no loss of meibomian glands): 100 eyes; grade 1 (gland dropout area <1/3 of the total meibomian glands): 85 eyes; grade 2 (gland dropout area 1/3 to 2/3): 68 eyes; and grade 3 (gland dropout >2/3): 47 eyes.

Conclusion

Keratoconus shows significant meibomian gland dropout and distortion that can be recorded by noncontact meibography. Sirius meibography is a simple, cost-effective method of evaluating meibomian gland dropout as a part of the routine refractive examination.

Comparison of Standard Versus Accelerated Corneal Collagen Cross-Linking for Keratoconus: A Meta-Analysis

Purpose

To systematically compare epithelial-off standard (SCXL) to accelerated corneal collagen cross-linking (ACXL) for the treatment of keratoconus.

Methods

PubMed, Embase, the Cochrane Library, and the US trial registry were searched for trials comparing SCXL and ACXL for keratoconus up to October 2017. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated. Primary outcomes were changes in uncorrected distance visual acuity, maximum keratometry (Kmax), and mean keratometry (mean K). Secondary outcomes were changes in corrected distance visual acuity, mean refractive spherical equivalent, central corneal thickness (CCT), and endothelial cell density (ECD).

Results

Eleven trials were included. For primary outcomes, SCXL showed a greater reduction in Kmax (SMD 0.32; 95% CI 0.16, 0.48) than ACXL. For secondary outcomes, the decrease in CCT (SMD 0.32; 95% CI 0.03, 0.61) and ECD (SMD 0.26; 95% CI 0.06, 0.46) was less with ACXL than with SCXL. For the other outcomes, there were no statistically significant differences.

Conclusions

SCXL has a greater effect in terms of reduction in Kmax than ACXL, while ACXL induces less reduction in CCT and ECD than SCXL. Further well-designed randomized controlled trials comparing ACXL and SCXL are indicated.

Transepithelial versus Epithelium off Crosslinking for Treating Keratoconus among Jordanians

Background:

The progression of keratoconus is stabilized with the help of corneal collagen cross-linking (CXL) supported through photosynthesized riboflavin.

Objective:

This study aims to compare the effectiveness of the transepithelial procedure and epithelium off procedure of corneal collagen crosslinking among keratoconus patients in Jordan.

Methods:

The study recruited 80 patients suffering from progressive keratoconus, from a tertiary care setting in Jordan. These participants were randomly divided into two groups; group 1 with 40 participants subjected to transepithelial (Corneal collagen cross-linking) CXL; and 40 participants in group 2 received conventional epithelium off CXL.

Results:

Improvement was observed in the mean contact lens, which corrected distance visual acuity (CDVA) from logMAR 0.332 ± 0.09 (group 1), 0.35 ± 0.09 (group 2) to 0.241 ± 0.07 (group 1), 0.21 ± 0.07 (group 2), respectively at the end of follow-up (12 months). The mean pachymetry improved from 429.81 ± 18.96 μm (group 1), 430.08 ± 17.05 μm (group 2) to 436.5 ± 15.49 μm (group 1), 436.44 ± 12.53 μm (group 2), respectively, after twelve months. Additionally, the mean Sim K astigmatism declined from 7.0 ± 2.0 (group 1), 6.73 ± 1.98 (group 2) to 5.97 ± 1.88 (group 1), 5.53 ± 0.08 (group 2) respectively at twelve months post-treatment. Majority of the patients in group 2 experienced more pain as compared to group 1 participants.

Conclusion:

The effectiveness of a cross-linking procedure related to keratometry readings and corneal thickness showed that conventional (epithelium off) CXL method is more effective than transepithelial CXL.

Secondary Angle Closure due to Crystalline Lens Dislocation in a Patient with Atopic Dermatitis and Chronic Eye Rubbing

Purpose

To report an unusual case of ectopia lentis and angle closure in a patient with chronic eye rubbing.

Methods

A 57-year-old male with a history of poorly controlled atopic dermatitis presented with right eye pain, decreased vision, and an intraocular pressure (IOP) of 55 mm Hg. He had no past history of ocular disease and no reported history of trauma. He did report a history of chronic eye rubbing.

Results

Best corrected visual acuity was hand motions. The examination revealed severe atopic keratoconjunctivitis in both eyes, microcystic corneal edema of the right eye, and 2+ nuclear sclerosis in both eyes. Gonioscopy showed no visible angle structures OD and an open angle OS. Topical and oral IOP-lowering medications and a laser iridotomy were unsuccessful at lowering IOP. He was taken to the operating room for a lensectomy and was found to have 9 clock hours of zonular dehiscence and a dislocated lens. After lensectomy, the IOP improved to 9 mm Hg on postoperative day 1. A follow-up examination at 2 weeks showed improved acuity to 20/150 with a pinhole and an IOP of 10 mm Hg. A dilated examination OS did not reveal significant phacodonesis, and the patient was referred for a possible sutured sulcus lens or anterior chamber intraocular lens.

Conclusions

It is important for the provider to consider ectopia lentis in the differential for patients with pupillary block angle closure. For patients with atopic disease, one should be aware that eye rubbing may be a cause of zonular dehiscence, even in the absence of reported trauma or prior intraocular surgery.

Altered tear inflammatory profile in Indian keratoconus patients - The 2015 Col Rangachari Award paper

Purpose:

Conventionally, keratoconus (KC) has been considered a noninflammatory corneal ectatic disorder. Recent evidence suggests a possible role of inflammation in the pathogenesis of KC. Hence, we analyzed the levels of inflammatory factors in the tear fluid of Indian KC patients.

Methods:

Tear fluid samples were collected from age- and sex-matched healthy controls and KC patients (with different grades). The levels of the inflammatory factors in tears were analyzed using cytometric bead array (Human Soluble Protein Flex Set System, BD Biosciences) for levels of interleukin-1α (IL-1α), IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-9, IL-10, IL-12p70, IL-23p40, IL-13, IL-17A, IL-17F, IL-21, interferon-α (IFNα), IFNγ, tumor necrosis factor-α, CCL2/monocyte chemotactic protein-1, CCL4/macrophage inflammatory protein-1β (MIP-1β), MIP-1α, CCL5/RANTES, CXCL10/IP10, ICAM1, CD62E, vascular endothelial growth factor and transforming growth factor β.

Results:

An increase in Kmax and Kmean, and a decrease in central corneal thickness was observed with increasing grades of KC. Tear analysis showed that most of the tear soluble factors, including cytokines, chemokines, growth factors and cell adhesion molecules were significantly elevated in the KC patients compared to the controls.

Conclusion:

Our findings suggest that inflammatory factors associated with KC may play a role in its pathogenesis. This opens the potential to explore anti-inflammatory strategies to either halt or delay the progression of KC.

In vivo confocal microscopy and tear cytokine analysis in post-LASIK ectasia

AIM

Corneal keratectasia is one of the complications associated with laser in situ keratomileusis (LASIK) that results in vision impairment. The pathogenesis of post-LASIK ectasia (PLE) remains underexplored. We report the tear cytokine profile and in vivo confocal microscopy (IVCM) findings in eyes with PLE.

METHODS

This retrospective study included age-matched 7 (14 eyes) post-LASIK controls (PLCs) and 6 (12 eyes) PLE subjects. Corneal topography was used to categorise the subjects into PLC and PLE groups. Ocular Surface Disease Index (OSDI) scores obtained were based on standard questionnaire and IVCM images were used to determine corneal dendritic cells density (DCD) and sub-basal nerve plexus morphology. Inflammatory cytokines/chemokines in the tears were quantified using flow cytometry based cytometric bead array.

RESULTS

Pentacam-based scores, OSDI scores and corneal DCD were significantly (p<0.05) higher in patients with PLE compared with PLC. Discomfort-related subscale of OSDI score exhibited a positive correlation with total corneal DCD in the PLE cohort. The fold difference of chemokine (C-C motif) ligand/monocyte chemotactic protein-1 (CCL2/MCP1) (3.4±0.6) was found to be significantly (p<0.05) higher in the PLE cohorts and a positive correlation between CCL2/MCP1 levels and total corneal DCD was also observed in the PLE cohort.

CONCLUSION

The current study found a significant difference in the tear film cytokine profile between normal and PLE eyes. Presence of increased corneal dendritic cells and altered tear cytokines suggests an ongoing inflammatory response in PLE.

Induction of MMP‑1 and ‑3 by cyclical mechanical stretch is mediated by IL‑6 in cultured fibroblasts of keratoconus

In order to understand the effect of mechanical stretch on corneal extracellular matrix remodeling, human keratoconus fibroblasts (HKCFBs) were subjected to cyclic stretch in vitro and the expression of matrix metalloproteinases (MMPs), tissue inhibitor of metalloproteinases (TIMPs), and inflammatory cytokines were evaluated. HKCFBs were seeded into a flexible membrane base and subjected to a cyclic stretch regimen of 10% equibiaxial stretch at a stretching frequency of 1 Hz for 6 h using a Flexcell tension unit. An antibody directed against interleukin‑6 (IL‑6 Ab) was used to investigate the roles of IL‑6 on mechanical stretch mediated regulation of MMP in HKCFBs. Culture supernatants were assayed using an enzyme‑linked immunosorbent assay for MMP‑1 and ‑3, TIMP‑1 and ‑2, and IL‑6. Total RNA from the cells was extracted, and quantitative polymerase chain reaction was used to determine mRNA for MMP‑1 and ‑3, TIMP‑1 and ‑2, and IL‑6. In stretched cells, levels of MMP‑1 and ‑3 demonstrated an increase compared with unstretched cells, but levels of TIMP‑1, and ‑2 revealed a decrease. Mechanical stretch significantly increased the mRNA expression and protein synthesis of IL‑6 compared with unstretched cells. IL‑6 induced MMP‑1 and ‑3 expression, whereas no significant effects were observed in levels of TIMP‑1 and ‑2 compared with the untreated control groups. Additionally, the IL‑6 Ab markedly inhibited the stretch‑induced increase in MMP‑1 and ‑3 in culture supernatants in a dose‑dependent manner. No significant differences in TIMP‑1 and ‑2 protein levels were detected between stretched cells treated with IL‑6 Ab and stretched cells without IL‑6 Ab treatment. These results indicate that cyclical mechanical stretch augments IL‑6 production and MMP expression, and reduces levels of TIMP in HKCFBs. Thus, it is suggested that IL‑6 mediates the stretch‑induced MMP expression.

Molecular and Histopathological Changes Associated with Keratoconus

Keratoconus (KC) is a corneal thinning disorder that leads to loss of visual acuity through ectasia, opacity, and irregular astigmatism. It is one of the leading indicators for corneal transplantation in the Western countries. KC usually starts at puberty and progresses until the third or fourth decade; however its progression differs among patients. In the keratoconic cornea, all layers except the endothelium have been shown to have histopathological structural changes. Despite numerous studies in the last several decades, the mechanisms of KC development and progression remain unclear. Both genetic and environmental factors may contribute to the pathogenesis of KC. Many previous articles have reviewed the genetic aspects of KC, but in this review we summarize the histopathological features of different layers of cornea and discuss the differentially expressed proteins in the KC-affected cornea. This summary will help emphasize the major molecular defects in KC and identify additional research areas related to KC, potentially opening up possibilities for novel methods of KC prevention and therapeutic intervention.

Signs and Symptoms of Dry Eye in Keratoconus Patients Before and After Intrastromal Corneal Rings Surgery

PURPOSE

Based on the relationship between keratoconus and dry eye, the aim of this study was to evaluate changes in signs and symptoms of dry eye in keratoconus patients before and after intrastromal corneal ring surgery.

METHODS

Fifteen keratoconus patients were enrolled in Fundación Jiménez-Díaz of Madrid and University Clinic of Optometry of the Universidad Complutense de Madrid (Madrid, Spain). Tear break up time (TBUT), Schirmer test without anesthesia, corneal staining, diadenosine tetraphosphate (Ap₄A) concentration, and ocular surface disease index (OSDI) were evaluated. Impression cytology combined with laser confocal microscopy was performed to evaluate goblet cell density, mucin cloud height (MCH), and cell layer thickness (CLT). All measurements were performed before (pre) surgery, 1 month (post) and 6 months after surgery (post6m).

RESULTS

We found no statistical differences in time in Schirmer test, TBUT, and corneal staining. OSDI scores were 44.96  ±  8.65, 26.30 ± 6.79, and 19.31 ± 4.28 for (pre), (post), and (post6m) surgery, respectively (p < 0.001). Impression cytology showed a decrease in cell density at (post6m) compared with presurgery (47.36 ± 35.15 cells/mm² and 84.88 ± 32.08 cells/mm², respectively, p = 0.04). At post6m, the MCH increased compared with presurgery values (13.97 ± 4.26 µm and 6.77 ± 2.51 µm, respectively, p < 0.001). There was a statistically significant increase in CLT in time. Ap₄A tear concentrations were lower post6m than presurgery (1.02  ±  0.65 and 2.56   ± 1.10  µM, respectively, p < 0.001).

CONCLUSION

Intrastromal corneal ring surgery induces changes improving dry eye symptoms but no changes were found in signs of dry eye after surgery in keratoconus patients except for the MCH that increases drastically. More studies are needed to clarify the reason of its improvement.

Eye rubbing type and prevalence including contact lens 'removal-relief' rubbing

BACKGROUND

Eye rubbing is commonly associated with keratoconus and may contribute to disease onset and progression. Verbal counselling to avoid rubbing may not be successful and adverse consequences of rubbing, which occurs on contact lens removal may be more serious. This study examines the prevalence of 'removal-relief' rubbing and its potential consequences.

METHODS

Rubbing histories were recorded for contact lens wearing normal and keratoconic patients as well as for normal non-contact lens wearers. Analogue scaled responses were used to identify and compare abnormal rubbing habits.

RESULTS

Contact lens wearing patients (both with and without keratoconus) reported significantly more rubbing before contact lens insertion (p < 0.05) compared to non-contact lens wearers. Eye rubbing after contact lens removal ('removal-relief' rubbing) was found to be significantly more prevalent among contact lens-wearing keratoconic patients compared to contact lens-wearing non-keratoconic patients (p < 0.001 in both cases).

CONCLUSIONS

Rubbing-related trauma occurring before contact lens insertion may predispose the cornea to wound healing activities and greater levels of adverse response to contact lens wear. Such adverse responses could predispose the cornea to greater trauma, which occurs in response to rubbing on removal of contact lenses. Strong counselling to avoid eye rubbing is often not an adequate form of management for a significant number of patients with keratoconus. Evidence of relapses indicates the need for better methods of counselling and for them to be repeated regularly. Apart from keratoconus, any other keratectasia, corneal disease or wound healing (including post-surgical) may increase susceptibility to corneal rubbing trauma. Such cases also appear to warrant counselling on avoidance of rubbing.

Corneal cross-linking treatment of keratoconus

Keratoconus as the most common cause of ectasia is one of the leading cause of corneal transplants worldwide. The current available therapies do not modify the underlying pathogenesis of the disease, and none of the available approaches but corneal transplant hinder the ongoing ectasia. Several studies document Crosslink defect between collagen fibrils in the pathogenesis of keratoconus. Collagen cross link is a relatively new approach that with the application of the riboflavin and ultraviolet A, new covalent bands reform. Subjective and objective results following this method seem to be promising. Endothelial damage besides other deep structural injury, which is the major concern of this technique have not yet been reported, when applying the standard method.

Lamellar changes in the keratoconic cornea

PURPOSE

The purpose of this study was to identify ultrastructural changes associated with ectasia and to determine the association between lamellar count and corneal thinning.

METHODS

Five surgically removed keratoconic corneal buttons and four, non-keratoconic, normal eye bank control corneas were processed for transmission electron microscopy using an established protocol, ensuring minimal tissue distortion. A sequence of overlapping digital images, spanning the full apical cone corneal thickness, was assembled. A seamless digital montage was printed at 5000× magnification. Lamellae were counted in the anterior-posterior orientation, along a linear line, using established criteria for identification of individual lamellae.

RESULTS

The stromal thickness estimated as a 95% confidence interval for the mean, CI (0.95), in the keratoconic corneas was 372 ± 62 μm, while in the normal cornea, it was 446 ± 89 μm. All keratoconic corneas showed ultrastructural evidence of lamellar splitting and a loss of interweaving anterior lamellae. In the keratoconic corneas, the median total linear stromal lamellar absolute count tangential to the corneal surface was 362, (25th percentile; 75th percentile) = (355; 365) lamellae and in the normal cornea, 246, (25th percentile; 75th percentile) = (239; 251). The linear lamellar density in the keratoconic corneas was estimated as CI (0.95) 117 ± 22 and 86 ±19 lamellae per 100 μm in the anterior and posterior portion of the stroma, respectively. In normal cornea, the linear lamellar density was estimated as CI (0.95) 51 ± 8 and 80 ± 20 lamellae per 100 μm. The mean difference of linear lamellar count between the anterior and the posterior portion of the cornea was estimated as CI (0.95) 31 ± 23 for keratoconic corneas and -29 ± 28 for the normal corneas.

CONCLUSIONS

The current morphometric analysis of ultrastructural changes suggests that ectasia and thinning in keratoconus is associated with lamellar splitting into multiple bundles of collagen fibrils and loss of anterior lamellae. These structural changes, possibly in addition to lateral shifting of lamellae due to the pressure gradient over the cornea, are a potential explanation to the central loss of mass.

Indications and techniques employed for keratoplasty in the Eastern province of Saudi Arabia: 6 years of experience

BACKGROUND AND OBJECTIVES

Keratoplasty services in Saudi Arabia have progressed steadily in the past few decades. We sought to identify the leading indications and types of keratoplasty performed in the Eastern Province of Saudi Arabia over a six-year period and to compare these indications with published data.

DESIGN AND SETTING

This was a retrospective descriptive analysis of the records of patients who underwent keratoplasty at four ophthalmology centers in the Eastern Province between 2008 and 2013.

PATIENTS AND METHODS

All keratoplasty procedures were included in the analysis. The primary surgical indication and type of surgery were identified for each case.

RESULTS

Keratoplasties included 570 penetrating keratoplasty, 217 deep lamellar keratoplasty, 80 triple procedures, 24 descemet stripping automated endothelial keratoplasty and 12 Boston keratoprosthesis implantations. The mean age of all patients was 28.8 years (range 14-72 years), and 58.9% of the patient were males. The lead.ing indication for keratoplasty was keratoconus 53.10%, bullous keratopathy 13.80%, corneal scarring 10.7%, regrafts 9.1%, and stromal dystrophies 4.9%.

CONCLUSIONS

In this study, the leading indications for keratoplasty were keratoconus, bullous keratopathy, corneal scarring, regrafts and stromal dystrophies. A significant increasing trend for descemet's stripping automated endothelial keratoplasty surgeries was observed in spite of the number of cases.

Keratoconus: an inflammatory disorder?

Keratoconus has been classically defined as a progressive, non-inflammatory condition, which produces a thinning and steepening of the cornea. Its pathophysiological mechanisms have been investigated for a long time. Both genetic and environmental factors have been associated with the disease. Recent studies have shown a significant role of proteolytic enzymes, cytokines, and free radicals; therefore, although keratoconus does not meet all the classic criteria for an inflammatory disease, the lack of inflammation has been questioned. The majority of studies in the tears of patients with keratoconus have found increased levels of interleukin-6 (IL-6), tumor necrosis factor-α(TNF-α), and matrix metalloproteinase (MMP)-9. Eye rubbing, a proven risk factor for keratoconus, has been also shown recently to increase the tear levels of MMP-13, IL-6, and TNF-α. In the tear fluid of patients with ocular rosacea, IL-1α and MMP-9 have been reported to be significantly elevated, and cases of inferior corneal thinning, resembling keratoconus, have been reported. We performed a literature review of published biochemical changes in keratoconus that would support that this could be, at least in part, an inflammatory condition.

The genetic and environmental factors for keratoconus

Keratoconus (KC) is the most common cornea ectatic disorder. It is characterized by a cone-shaped thin cornea leading to myopia, irregular astigmatism, and vision impairment. It affects all ethnic groups and both genders. Both environmental and genetic factors may contribute to its pathogenesis. This review is to summarize the current research development in KC epidemiology and genetic etiology. Environmental factors include but are not limited to eye rubbing, atopy, sun exposure, and geography. Genetic discoveries have been reviewed with evidence from family-based linkage analysis and fine mapping in linkage region, genome-wide association studies, and candidate genes analyses. A number of genes have been discovered at a relatively rapid pace. The detailed molecular mechanism underlying KC pathogenesis will significantly advance our understanding of KC and promote the development of potential therapies.

Corneal collagen crosslinking in keratoconus and other eye disease

Keratoconus is a condition characterized by biomechanical instability of the cornea, presenting in a progressive, asymmetric and bilateral way. Corneal collagen crosslinking (CXL) with riboflavin and Ultraviolet-A (UVA) is a new technique of corneal tissue strengthening that combines the use of riboflavin as a photo sensitizer and UVA irradiation. Studies showed that CXL was effective in halting the progression of keratoconus over a period of up to four years. The published studies also revealed a reduction of max K readings by more than 2 D, while the postoperative spherical equivalent (SEQ) was reduced by an average of more than 1 D and refractive cylinder decreased by about 1 D. The major indication for the use of CXL is to inhibit the progression of corneal ecstasies, such as keratoconus and pellucid marginal degeneration. CXL may also be effective in the treatment and prophylaxis of iatrogenic keratectasia, resulting from excessively aggressive photo ablation. This treatment has been used to treat infectious corneal ulcers with apparent favorable results. Most recent studies demonstrate the beneficial impact of CXL for iatrogenic ecstasies, pellucid marginal degeneration, infectious keratitis, bullous keratopathy and ulcerative keratitis. Several long-term and short-term complications of CXL have been studied and documented. The possibility of a secondary infection after the procedure exists because the patient is subject to epithelial debridement and the application of a soft contact lens. Formation of temporary corneal haze, permanent scars, endothelial damage, treatment failure, sterile infiltrates, bullous keratopathy and herpes reactivation are the other reported complications of this procedure.