The Enigma of Environmental Factors in Keratoconus

Identification of hub genes and molecular pathways in keratoconus by integrating bioinformatics and literature mining at the RNA level

OBJECTIVE

Keratoconus (KC) is a condition characterized by progressive corneal steepening and thinning. However, its pathophysiological mechanism remains vague. We mainly performed literature mining to extract bioinformatic and related data on KC at the RNA level. The objective of this study was to explore the potential pathological mechanisms of KC by identifying hub genes and key molecular pathways at the RNA level.

METHODS

We performed an exhaustive search of the PubMed database and identified studies that pertained to gene transcripts derived from diverse corneal layers in patients with KC. The identified differentially expressed genes were intersected, and overlapping genes were extracted for further analyses. Significantly enriched genes were screened using "Gene Ontology" (GO) and "Kyoto Encyclopedia of Genes and Genomes" (KEGG) analysis with the "Database for Annotation, Visualization, and Integrated Discovery" (DAVID) database. A protein-protein interaction (PPI) network was constructed for the significantly enriched genes using the STRING database. The PPI network was visualized using the Cytoscape software, and hub genes were screened via betweenness centrality values. Pathways that play a critical role in the pathophysiology of KC were discovered using the GO and KEGG analyses of the hub genes.

RESULTS

68 overlapping genes were obtained. Fifty genes were significantly enriched in 67 biological processes, and 16 genes were identified in 7 KEGG pathways. Moreover, 14 nodes and 32 edges were identified via the PPI network constructed using the STRING database. Multiple analyses identified 4 hub genes, 12 enriched biological processes, and 6 KEGG pathways. GO enrichment analysis showed that the hub genes are mainly involved in the positive regulation of apoptotic process, and KEGG analysis showed that the hub genes are primarily associated with the interleukin-17 (IL-17) and tumor necrosis factor (TNF) pathways. Overall, the matrix metalloproteinase 9, IL-6, estrogen receptor 1, and prostaglandin-endoperoxide synthase 2 were the potential important genes associated with KC.

CONCLUSION

Four genes, matrix metalloproteinase 9, IL-6, estrogen receptor 1, and prostaglandin endoperoxide synthase 2, as well as IL-17 and TNF pathways, are critical in the development of KC. Inflammation and apoptosis may contribute to the pathogenesis of KC.

No Evidence of Chronic Infection in a Metagenomic Sequencing Study of the Keratoconus Corneal Epithelium

Objectives: This study aims to assess the presence of pathogenic microorganisms in the corneal epithelial layer of keratoconus patients. Methods: DNA was extracted from corneal epithelial samples procured from ten individual keratoconus eyes and three healthy controls. Metagenomic next-generation sequencing (mNGS) was performed to detect ocular microbiota using an agnostic approach. Results: Metagenomic sequencing revealed a low microbial read count in corneal epithelial samples derived from both keratoconus eyes (average: 530) and controls (average: 622) without a statistically significant difference (p = 0.29). Proteobacteria were the predominant phylum in both keratoconus and control samples (relative abundance: 72% versus 79%, respectively). Conclusions: The overall low microbial read count and the lack of difference in the relative abundance of different microbial species between keratoconus and control samples do not support the hypothesis that a chronic corneal infection is implicated in the pathogenesis of keratoconus. These findings do not rule out the possibility that an acute infection may be involved in the disease process as an initiating event.

Bioinformatics analysis of signature genes related to cell death in keratoconus

Keratoconus is corneal disease in which the progression of conical dilation of cornea leads to reduced visual acuity and even corneal perforation. However, the etiology mechanism of keratoconus is still unclear. This study aims to identify the signature genes related to cell death in keratoconus and examine the function of these genes. A dataset of keratoconus from the GEO database was analysed to identify the differentially expressed genes (DEGs). A total of 3558 DEGs were screened from GSE151631. The results of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that they mainly involved in response to hypoxia, cell-cell adhesion, and IL-17 signaling pathway. Then, the cell death-related genes datasets were intersected with the above 3558 DEGs to obtain 70 ferroptosis-related DEGs (FDEGs), 32 autophagy-related DEGs (ADEGs), six pyroptosis-related DEGs (PDEGs), four disulfidptosis-related DEGs (DDEGs), and one cuproptosis-related DEGs (CDEGs). After using Least absolute shrinkage and selection operator (LASSO), Random Forest analysis, and receiver operating characteristic (ROC) curve analysis, one ferroptosis-related gene (TNFAIP3) and five autophagy-related genes (CDKN1A, HSPA5, MAPK8IP1, PPP1R15A, and VEGFA) were screened out. The expressions of the above six genes were significantly decreased in keratoconus and the area under the curve (AUC) values of these genes was 0.944, 0.893, 0.797, 0.726, 0.882 and 0.779 respectively. GSEA analysis showed that the above six genes mainly play an important role in allograft rejection, asthma, and circadian rhythm etc. In conclusion, the results of this study suggested that focusing on these genes and autoimmune diseases will be a beneficial perspective for the keratoconus etiology research.

Racial Variation in Visual Impairment of Patients With Keratoconus at Presentation

PURPOSE

This study aimed to investigate racial disparities in the severity of keratoconus (KCN) at presentation, their intersection with socioeconomic variables, and other factors associated with visual impairment.

METHODS

This retrospective cohort study examined medical records of 1989 patients (3978 treatment-naive eyes) with a diagnosis of KCN seen at Wilmer Eye Institute between 2013 and 2020. A multivariable regression model adjusting for age, sex, race, insurance type, KCN family history, atopy, smoking status, and vision correction method examined factors associated with visual impairment, defined as a best available visual acuity of worse than 20/40 in the better eye.

RESULTS

Demographically, Asian patients were the youngest (33.4 ± 14.0 years) ( P < 0.001), and Black patients had the highest median area deprivation index (ADI) of 37.0 [interquartile range (IQR): 21.0-60.5] ( P < 0.001). Multivariable analysis showed a higher risk of visual impairment for Black (OR 2.25, 95% CI, 1.71-2.95) versus White patients. Medicaid (OR 2.59, 95% CI, 1.75-3.83) and Medicare (OR 2.48, 95% CI, 1.51-4.07) were also associated with a higher odds of visual impairment compared with private insurance, and active smokers were more likely to have visual impairment than those with no prior smoking history (OR 2.17, 95% CI, 1.42-3.30). Eyes of Black patients had the highest maximum keratometry (Kmax) (56.0 ± 11.0D) ( P = 0.003) and the lowest thinnest pachymetry (463.2 ± 62.5 µm) ( P = 0.006) compared with eyes of other races.

CONCLUSIONS

Black race, government-funded insurance, and active smoking were significantly associated with increased odds of visual impairment in adjusted analyses. Black race was also associated with higher Kmax and lower thinnest pachymetry, suggesting that Black patients have more severe disease at presentation.

Keratoconus Management in the Community: A Survey of Optometrists

OBJECTIVES

Defining the patterns of practice and referral criteria of optometrists within New Zealand to investigate the diagnosis and management of keratoconus.

METHODS

Optometrists recruited through the New Zealand Association of Optometrists, Cornea and Contact Lens Society of New Zealand, and private practices were invited to complete an anonymous survey.

RESULTS

Responses were received from 168 optometrists (representing 20.0% of the optometrist population). Half (48%) of optometrists had ≥15 years of experience, and 22% prescribed soft contact lenses daily, whereas only 6.4% prescribed rigid gas-permeable (RGP) lenses daily. The main barriers to prescribing RGPs were experience with fitting, low market demand, and patient discomfort. When referring to an ophthalmologist, 41% reported referring on progression of corneal parameters, 27% on initial diagnosis, 21% at no set time, and 10% with a reduction in visual acuity. Most optometrists (64%) would refer for possible surgery when visual acuity dropped between 6/9 and 6/12. Optometrists with greater experience were more likely to prescribe RGP lenses and co-manage patients with ophthalmologists. Ownership of a corneal imaging unit suggested an increased likelihood of prescribing RGP lenses but did not alter referral patterns.

CONCLUSION

This survey provides an overview of current practice and highlights the importance of optometrists in the diagnosis and management of keratoconus. There was a significant discrepancy in keratoconus management, regarding optical correction modality and referral criteria for ophthalmology review. Further interdisciplinary work is required between optometry and ophthalmology to standardize referral guidelines and enhance visual outcomes.

Ethnicity, Progressive Keratoconus, and Outcomes after Corneal Cross-Linking in Southern Israel

PURPOSE

To assess clinical outcomes of corneal cross-linking (CXL) intervention in a population diagnosed with progressive keratoconus.

METHODS

This single-center retrospective cohort study included consecutive patients who underwent standard CXL or accelerated CXL for progressive keratoconus at a major teaching hospital in southern Israel between January 2015 and December 2019. Patients' medical files were reviewed, and pre-operative and post-operative data regarding demographics and clinical and tomographic characteristics were extracted and analyzed.

RESULTS

This study included 166 patients (representing 198 eyes), out of which 98 patients (123 eyes) were ethnically Bedouin, and 68 patients (75 eyes) were ethnically Jewish. Overall, 126 patients (144 eyes) had a follow-up of at least 12 months (16.84 ± 5.76). The mean patient age was 20.62 ± 7.1 years old. There were significant baseline differences between the two ethnic groups in best-corrected visual acuity (BCVA; p < 0.001), uncorrected visual acuity (UCVA; p < 0.001), mean keratometry (p = 0.028), and corneal thickness (p < 0.001). Significant changes in BCVA, UCVA, and pachymetry parameters within each group were found after 12 months. Negative binomial regression analysis showed a maximal keratometry below 55D (RR = 1.247, p < 0.001), and a standard CXL procedure (RR = 1.147, p = 0.041) are significantly related to the stability of KC after 12 months. However, the effect size of the origin of patients is negligible (RR = 1.047, p = 0.47).

CONCLUSIONS

In this study, the Bedouin population suffered from more progressive keratoconus when compared to the Jewish population. CXL was significantly effective in improving BCVA and UCVA in both groups after 12 months of follow-up. The effect size of the origin of patients on the stability of KC was found to be negligible.

Selective Modulation of the Keratoconic Stromal Microenvironment by FSH and LH

Keratoconus (KC) affects the corneal structure, with thinning and bulging outward into a conelike shape. Irregular astigmatism and decreased visual acuity appear during puberty and progress into the mid-30s, with unpredictable disease severity. The cause of KC is recognized as multifactorial, but remains poorly understood. Hormone imbalances are a significant modulator of the onset of KC. This study sought to investigate the role of gonadotropins, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) in KC, using a three-dimensional, self-assembled matrix in vitro model. Healthy corneal fibroblasts and human KC cells in the corneal stroma were isolated, cultured, and stimulated with stable vitamin C to promote extracellular matrix assembly. Cultures were further stimulated with 2.5 or 10 mIU/mL FSH and 5 or 35 mIU/mL LH. Samples were evaluated for cell proliferation and morphology via BrdU assay and imaging; protein expression was assessed via Western blot analysis. Proliferation was significantly greater in human KC cells compared to healthy corneal fibroblasts with LH stimulation, but no changes were found with FSH stimulation. Additionally, in sex hormone receptors, fibrotic markers, proteoglycans, and members of the gonadotropin signaling pathway were significantly changed, largely driven by exogenous LH. The impact of exogenous FSH/LH in the KC stromal microenvironment was demonstrated. These results highlight the need to further examine the role of FSH/LH in KC and in human corneal homeostasis.

Comparing Repeatability and Agreement between Commonly Used Corneal Imaging Devices in Keratoconus

SIGNIFICANCE

Keratometry and pachymetry are important for diagnosis and monitoring of keratoconus. Many corneal imaging units exist, but comparison to determine repeatability and agreement is paramount for adequate keratoconus management in primary and secondary care.

PURPOSE

This study aimed to evaluate the repeatability and agreement of a Placido disc-based videokeratoscope (Melbourne, Victoria, Australia) used in primary care with spectral-domain optical coherence tomography (Optopol Technology, Zawiercie, Poland) and Scheimpflug corneal tomography (Oculus, Wetzlar, Germany) in secondary care.

METHODS

This was a prospective single-center study where one eye was randomized to have central corneal thickness;thinnest corneal thickness (TCT); and maximum, mean, steep, and flat keratometry (Kmax, Kmean, Ksteep, and Kflat, respectively), measured with all three devices. Three measurements were completed per device to assess intraobserver repeatability.

RESULTS

A total of 110 eyes from 110 patients with keratoconus were analyzed. Repeatability was best with the Pentacam for central corneal thickness, Kmax, Kmean, Ksteep, and Kflat parameters (precision, 9.21, 0.8, 0.38, 0.52, and 0.58). The Medmont had better repeatability than the Revo with Kmax, Kmean, Ksteep, and Kflat (precision, 1.41,1.35,1.43, and 1.59). Revo had the best repeatability with TCT (precision, 3.81). The intraclass correlation coefficient was >0.94 for all parameters in all devices. Agreement was generally poor between devices. However, there was good agreement between Pentacam and Medmont Kflat measurements ( P > .05).

CONCLUSIONS

Repeatability of keratometry parameters with the Pentacam and Medmont was greater than the Revo, suggesting a lower threshold for detecting change in anterior corneal parameters. The Revo had the greatest repeatability for TCT, suggesting a lower threshold for detecting thinning in disease progression and corneal-crosslinking safety. There was poor agreement between devices, and it is not recommended for them to be used interchangably.

Keratoconus International Consortium (KIC)- advancing keratoconus research

CLINICAL RELEVANCE

The Keratoconus International Consortium (KIC) will allow better understanding of keratoconus.

BACKGROUND

Keratoconus is a disorder characterised by corneal elevation and thinning, leading to reduced vision. The current gaps in understanding of this disease will be discussed and the need for a multi-pronged and multi-centre engagement to enhance our understanding of keratoconus will be highlighted.

DESIGN

KIC has been established to address the gaps in our understanding of keratoconus with the aim of collecting baseline as well as longitudinal data on several fields.

PARTICIPANTS

Keratoconus and control (no corneal condition) subjects from different sites globally will be recruited in the study.

METHODS

KIC collects data using an online, secure database, which enables standardised data collection at member sites. Data fields collected include medical history, clinical features, quality of life and economic burden questionnaires and possible genetic sample collection from patients of different ethnicities across different geographical locations.

RESULTS

There are currently 40 Australian and international clinics or hospital departments who have joined the KIC. Baseline data has so far been collected on 1130 keratoconus patients and indicates a median age of 29.70 years with 61% being male. A total of 15.3% report a positive family history of keratoconus and 57.7% self-report a history of frequent eye rubbing.

CONCLUSION

The strength of this consortium is its international, collaborative design and use of a common data collection tool. Inclusion and analyses of cross-sectional and longitudinal data will help answer many questions that remain in keratoconus, including factors affecting progression and treatment outcomes.

Unravelling the Impact of Cyclic Mechanical Stretch in Keratoconus-A Transcriptomic Profiling Study

Biomechanical and molecular stresses may contribute to the pathogenesis of keratoconus (KC). We aimed to profile the transcriptomic changes in healthy primary human corneal (HCF) and KC-derived cells (HKC) combined with TGFβ1 treatment and cyclic mechanical stretch (CMS), mimicking the pathophysiological condition in KC. HCFs (n = 4) and HKCs (n = 4) were cultured in flexible-bottom collagen-coated 6-well plates treated with 0, 5, and 10 ng/mL of TGFβ1 with or without 15% CMS (1 cycle/s, 24 h) using a computer-controlled Flexcell FX-6000T Tension system. We used stranded total RNA-Seq to profile expression changes in 48 HCF/HKC samples (100 bp PE, 70-90 million reads per sample), followed by bioinformatics analysis using an established pipeline with Partek Flow software. A multi-factor ANOVA model, including KC, TGFβ1 treatment, and CMS, was used to identify differentially expressed genes (DEGs, |fold change| ≥ 1.5, FDR ≤ 0.1, CPM ≥ 10 in ≥1 sample) in HKCs (n = 24) vs. HCFs (n = 24) and those responsive to TGFβ1 and/or CMS. PANTHER classification system and the DAVID bioinformatics resources were used to identify significantly enriched pathways (FDR ≤ 0.05). Using multi-factorial ANOVA analyses, 479 DEGs were identified in HKCs vs. HCFs including TGFβ1 treatment and CMS as cofactors. Among these DEGs, 199 KC-altered genes were responsive to TGFβ1, thirteen were responsive to CMS, and six were responsive to TGFβ1 and CMS. Pathway analyses using PANTHER and DAVID indicated the enrichment of genes involved in numerous KC-relevant functions, including but not limited to degradation of extracellular matrix, inflammatory response, apoptotic processes, WNT signaling, collagen fibril organization, and cytoskeletal structure organization. TGFβ1-responsive KC DEGs were also enriched in these. CMS-responsive KC-altered genes such as OBSCN, CLU, HDAC5, AK4, ITGA10, and F2RL1 were identified. Some KC-altered genes, such as CLU and F2RL1, were identified to be responsive to both TGFβ1 and CMS. For the first time, our multi-factorial RNA-Seq study has identified many KC-relevant genes and pathways in HKCs with TGFβ1 treatment under CMS, suggesting a potential role of TGFβ1 and biomechanical stretch in KC development.

To what extent is pregnancy-induced keratoconus progression reversible? A case-report and literature review

PURPOSE

This report aims to present a case with pregnancy-induced keratoconus (KC) progression and recovery in topographical parameters after a period from delivery/breastfeeding.

METHODS

A 29-year-old woman with bilateral KC experienced progression in maximum keratometry (Kmax; from 47.6 to 48.2 D in the OD and from 53.7 to 55.2 D in the OS) and several Pentacam indices in both eyes.

RESULTS

The Belin ABCD progression score remained unchanged in the right eye (A0B2C0D0) but increased in the left eye (from A2B3C1D1 to A2B4C1D1) (Pentacam HR, Oculus Optikgeräte GmbH, Wetzlar, Germany) during pregnancy/breastfeeding. About 6-months after cessation of breastfeeding, Kmax improved to baseline values in both eyes. Although there were improvements in "A" and "B" scores, final ABCD stage remained higher than the baseline value in the left eye.

CONCLUSIONS

The current report shows asymmetrically bilateral progression of KC during pregnancy and early post-delivery period, which was followed by a partial recovery in Pentacam parameters after discontinuation of breastfeeding. These findings seem to confirm the postulated link between pregnancy and KC progression. On the other hand, in patients with KC, pregnancy-induced corneal alterations might recover after delivery/breastfeeding and clinician should wait for stabilization of corneal parameters to determine treatment strategy.

The Underlying Relationship between Keratoconus and Down Syndrome

Keratoconus (KC) is one of the most significant corneal disorders worldwide, characterized by the progressive thinning and cone-shaped protrusion of the cornea, which can lead to severe visual impairment. The prevalence of KC varies greatly by ethnic groups and geographic regions and has been observed to be higher in recent years. Although studies reveal a possible link between KC and genetics, hormonal disturbances, environmental factors, and specific comorbidities such as Down Syndrome (DS), the exact cause of KC remains unknown. The incidence of KC ranges from 0% to 71% in DS patients, implying that as the worldwide population of DS patients grows, the number of KC patients may continue to rise significantly. As a result, this review aims to shed more light on the underlying relationship between KC and DS by examining the genetics relating to the cornea, central corneal thickness (CCT), and mechanical forces on the cornea, such as vigorous eye rubbing. Furthermore, this review discusses KC diagnostic and treatment strategies that may help detect KC in DS patients, as well as the available DS mouse models that could be used in modeling KC in DS patients. In summary, this review will provide improved clinical knowledge of KC in DS patients and promote additional KC-related research in these patients to enhance their eyesight and provide suitable treatment targets.

Corneal Crosslinking: Present and Future

Keratoconus is a progressive corneal thinning disorder that can lead to vision loss. In the last 2 decades, corneal crosslinking (CXL) has emerged as an effective method to halt the progression of keratoconus and reduce the number of patients requiring keratoplasty. The procedure has been adopted globally and has evolved to become a part of combination treatments to regularize the cornea and improve visual outcomes. CXL has even been extrapolated in managing other ocular pathologies such as progressive myopia, infectious keratitis, and bullous keratopathy. This review aims to summarize the current role of CXL in keratoconus and its alternative uses, and provide insights into future developments in this fast-developing field.

Associations Between Keratoconus and the Level of Sex Hormones: A Cross-Sectional Study

Purpose

To analyze the level of sex hormone in relation to keratoconus (KC).

Methods

Sixty-two eyes of 62 patients (12 females, 50 males) classified as KC and 120 eyes of 120 patients (21 females, 99 males) with mild to moderate myopia and astigmatism were analyzed. Plasma samples were collected and analyzed using a chemiluminescence immunoassay to determine the concentrations of estriol (E₃), estradiol (E₂), progesterone (P), and testosterone (T). Corneal morphological parameters, such as the central corneal thickness (CCT), thinnest corneal thickness (TCT), and maximum simulated keratometry (K_max), were measured using Pentacam and Sirius.

Results

The mean age was 23.73 ± 5.16 years for patients with KC and 23.68 ± 6.10 years for patients treated with laser vision correction (LVC). Among the patients with KC, 12 were female (19.35%) and 50 were male (80.65%). The majority of patients with KC were between 20 and 30 years old. In female patients, the concentration of T in the KC group was significantly lower than that in the LVC group (0.86 ± 0.33 vs. 1.18 ± 0.58 nmol/L; P = 0.044). There were positive correlations between T, CCT (r = 0.395, P = 0.023) and TCT (r = 0.378, P = 0.030) in female patients. In male patients, E₂ was higher in the KC group than the LVC group (143.75 ± 34.82 vs. 124.80 ± 43.56 pmol/L; P = 0.013), while T was significantly lower (11.59 ± 2.85 vs. 13.58 ± 4.77 nmol/L; P = 0.026). A positive correlation was found between E₂ and K_max (r = 0.222, P = 0.007) in male patients.

Conclusions

Conclusively, our results showed that T level was reduced in both female and male KC plasma, while E₂ was increased in male KC plasma. Different levels of sex hormones are correlated with KC, which, may provide the basis of a new technique for screening and diagnosing KC with or without the assistance of current imaging techniques. Moreover, the correlations between sex hormone alterations and KC provide compelling insight into KC etiopathogenesis.

Increased epithelial backscatter: A novel finding in subclinical and clinical keratoconus

BACKGROUND

To assess alterations in backscatter from the corneal epithelium, anterior stroma and lens surface in eyes with subclinical, mild and moderate keratoconus (KC).

METHODS

In this single-centre, cross-sectional study involving 24 eyes with subclinical KC, 107 eyes with manifest KC (mild = 40 and moderate = 67 eyes) and 90 controls, line densitometry was performed with Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany) to obtain simultaneous backscatter values for the corneal epithelium, anterior stroma and anterior lens surface. Backscatter values and Pentacam parameters were used in subsequent statistical analyses.

RESULTS

Eyes with subclinical, mild and moderate KC had similar epithelial and stromal backscatter (P > 0.05) that was significantly increased compared with the controls (P < 0.05). Although anterior lens surface backscatter did not differ between the control and KC groups (P > 0.05), it was significantly higher in the mild and moderate KC groups than in the subclinical KC group (P < 0.05). In the KC group (n = 131) epithelial backscatter was strongly correlated with stromal backscatter (r = 0.911, P < 0.0001).

CONCLUSIONS

Increased epithelial backscatter and a strong correlation with anterior stromal backscatter in the KC groups were consistent with the epithelium-stroma interaction involved in KC pathogenesis. Single-point backscatter analysis can be used with point clouds to construct epithelial and stromal backscatter maps in Pentacam to aid the detection of KC as a novel feature.

Environmental Risk Factors Associated With the Need for Penetrating Keratoplasty in Patients With Keratoconus

Purpose To identify environmental risk factors associated with the need for penetrating keratoplasty (PKP) (full-thickness corneal transplantation) in patients with keratoconus in a Middle Eastern country. Methods This is a retrospective case-control study. This study included patients with keratoconus who underwent PKPor were waitlisted for PKP. Controls were patients diagnosed with keratoconus who did not reach a stage that necessitates PKP. Groups were matched by age and gender. Chi-square test was used to figure out the association between different risk factors including eye rubbing, vernal keratoconjunctivitis (VKC), smoking, paternal consanguinity, eye dryness, family history, asthma, eczema, and diabetes with the need for PKP. Results A total of 111 patients were included in this study, there were 48 (43.26%) men and 63 (56.75%) women. The case group included 42 subjects and the control group included 69 subjects. We found statistically significant differences between the two groups in relation to eye rubbing (p=0.0005), VKC (p=0.005), paternal consanguinity (p=0.02), and smoking rate (p=0.04), all being significant in the group in need of PKP. On the other hand, we did not find out a statistically significant difference between the two groups in relation to family history (p=0.31), dryness (p=0.58), asthma (p=0.15), eczema (p=0.28), or diabetes (p=0.29). Conclusion This study has identified several risk factors associated with the need for PKP in patients with keratoconus, part of which are modifiable. These findings can benefit clinicians in community counseling and give recommendations that can help in preventing or - at least - delaying the need for PKP surgery in keratoconus, such as smoking cessation, aggressive treatment of VKC disease, eye rubbing avoidance, as well as raising awareness regarding the potential risks of paternal consanguinity in this disease entity.