A review of corneal imaging methods for the early diagnosis of pre-clinical Keratoconus

Injectable hydrogels based on biopolymers for the treatment of ocular diseases

Injectable hydrogels based on biopolymers, fabricated utilizing diverse chemical and physical methodologies, exhibit exceptional physical, chemical, and biological properties. They have multifaceted applications encompassing wound healing, tissue regeneration, and across diverse scientific realms. This review critically evaluates their largely uncharted potential in ophthalmology, elucidating their diverse applications across an array of ocular diseases. These conditions include glaucoma, cataracts, corneal disorders (spanning from age-related degeneration to trauma, infections, and underlying chronic illnesses), retina-associated ailments (such as diabetic retinopathy, retinitis pigmentosa, and age-related macular degeneration (AMD)), eyelid abnormalities, and uveal melanoma (UM). This study provides a thorough analysis of applications of injectable hydrogels based on biopolymers across these ocular disorders. Injectable hydrogels based on biopolymers can be customized to have specific physical, chemical, and biological properties that make them suitable as drug delivery vehicles, tissue scaffolds, and sealants in the eye. For example, they can be engineered to have optimum viscosity to be injected intravitreally and sustain drug release to treat retinal diseases. Their porous structure and biocompatibility promote cellular infiltration to regenerate diseased corneal tissue. By accentuating their indispensable role in ocular disease treatment, this review strives to present innovative and targeted approaches in this domain, thereby advancing ocular therapeutics.

Multi-modal imaging for the detection of early keratoconus: a narrative review

Keratoconus is a common progressive corneal disorder that can be associated with significant ocular morbidity. Various corneal imaging techniques have been used for the diagnosis of established cases. However, in the early stages of the disease, which include subclinical keratoconus and forme fruste keratoconus, detection of such cases can be challenging. The importance of detecting such cases is very important because early intervention can halt disease progression, improve visual outcomes and prevent postrefractive surgery ectasia associated with performing corneal refractive procedures in such patients. This narrative review aimed to examine several established and evolving imaging techniques for the detection of early cases of keratoconus. The utilization of combinations of these techniques may further increase their diagnostic ability.

Binocular vision parameters and visual performance in bilateral keratoconus corrected with spectacles versus rigid gas-permeable contact lenses

PURPOSE

To analyze binocular vision of individuals aged 18 to 35 years diagnosed with keratoconus, utilizing spectacles and rigid gas-permeable (RGP) contact lenses. Research was led by the Universidad Autónoma de Aguascalientes, México and Fundación Universitaria del Área Andina Pereira, Colombia.

METHODS

A single center, prospective non-randomized, comparative, interventional, open-label study, in which the differences in binocular vision performance with both spectacles and RGP contact lenses was carried out from December 2018 to December 2019. Sampling was performed according to consecutive cases with keratoconus that met the inclusion criteria until the proposed sample size was reached.

RESULTS

Rigid gas-permeable (RGP) contact lenses notably enhanced distance and near visual acuity in keratoconus patients compared to spectacles. Visual alignment analysis shows exophoria at both distances and is slightly higher with RGP contact lenses. The difference was statistically significant (p<0.05), with 82.5 % presenting compensated phoria with spectacles and pnly 42.50% with RGP contact lenses. Stereoscopic vision improved while wearing RGP contact lenses (42.59 %), although accommodation and accommodative flexibility remained within normal ranges.

CONCLUSIONS

Patients with keratoconus fitted with RGP contact lenses have improved binocular vision skills such as visual acuity, stereopsis, and accommodative flexibility. However, even when the vergence and motor system is decompensated with respect to normal ranges, the range between break and recovery points for both fusional reserves and the near point of convergence (NPC) improves with the use of RGP contact lenses, giving indications of an adaptive condition of the motor system from the medium to the long term.

Deep learning prediction of steep and flat corneal curvature using fundus photography in post-COVID telemedicine era

Recently, fundus photography (FP) is being increasingly used. Corneal curvature is an essential factor in refractive errors and is associated with several pathological corneal conditions. As FP-based examination systems have already been widely distributed, it would be helpful for telemedicine to extract information such as corneal curvature using FP. This study aims to develop a deep learning model based on FP for corneal curvature prediction by categorizing corneas into steep, regular, and flat groups. The EfficientNetB0 architecture with transfer learning was used to learn FP patterns to predict flat, regular, and steep corneas. In validation, the model achieved a multiclass accuracy of 0.727, a Matthews correlation coefficient of 0.519, and an unweighted Cohen's κ of 0.590. The areas under the receiver operating characteristic curves for binary prediction of flat and steep corneas were 0.863 and 0.848, respectively. The optic nerve and its peripheral areas were the main focus of the model. The developed algorithm shows that FP can potentially be used as an imaging modality to estimate corneal curvature in the post-COVID-19 era, whereby patients may benefit from the detection of abnormal corneal curvatures using FP in the telemedicine setting.

The Level of Awareness of Keratoconus Among the General Population in Hail Region, Saudi Arabia

Background Keratoconus (KC) is a non-inflammatory corneal disease with an early onset in adulthood, leading to a reduction in visual acuity. This study aims to evaluate the level of awareness of keratoconus among the general population in the Hail region of Saudi Arabia. Methodology Data were collected through a pre-designed and pre-validated online questionnaire (Appendix) distributed via social media platforms. The questionnaire was divided into two sections. The first section included demographic profiles, while the second section inquired about knowledge and awareness regarding Keratoconus. The collected data was reviewed, coded, and inputted into IBM Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp. Statistical analyses were performed using the Pearson Chi-Square test, with statistical significance set at p<0.05. Results The total number of respondents was 550, among whom 40% were males and 60% were females. 79.6% of the participants were in the age range of 18-30 years. The level of education and a positive family history of KC showed significant associations with the level of knowledge about KC (p<0.05). The age group had a non-significant association (p=0.059), while gender had a significant association with the level of knowledge about keratoconus (p<0.05). Conclusion In conclusion, the overall awareness regarding KC progression, interventions, and the consequences of eye rubbing was limited among the participants. Specific efforts are crucial to enhance public awareness and understanding of KC, ensuring a more informed and proactive approach to eye health within the community.

Ocular condition prognosis in Keratoconus patients after corneal ring implantation using artificial neural networks

The common disorder, Keratoconus (KC), is distinguished by cumulative corneal slimming and steepening. The corneal ring implantation has become a successful surgical procedure to correct the KC patient's vision. The determination of suitable patients for the surgery alternative is among the paramount concerns of ophthalmologists. To reduce the burden on them and enhance the treatment, this research aims to previse the ocular condition of KC patients after the corneal ring implantation. It focuses on predicting post-surgical corneal topographic indices and visual characteristics. This study applied an efficacious artificial neural network approach to foretell the aforementioned ocular features of KC subjects 6 and 12 months after implanting KeraRing and MyoRing based on the accumulated data. The datasets are composed of sufficient numbers of corneal topographic maps and visual characteristics recorded from KC patients before and after implanting the rings. The visual characteristics under study are uncorrected visual acuity (UCVA), sphere (SPH), astigmatism (Ast), astigmatism orientation (Axe), and best corrected visual acuity (BCVA). In addition, the statistical data of multiple KC subjects were registered, including three effective indices of corneal topography (i.e., Ast, K-reading, and pachymetry) pre- and post-ring embedding. The outcomes represent the contribution of practical training of the introduced models to the estimation of ocular features of KC subjects following the implantation. The corneal topographic indices and visual characteristics were estimated with mean errors of 7.29% and 8.60%, respectively. Further, the errors of 6.82% and 7.65% were respectively realized for the visual characteristics and corneal topographic indices while assessing the predictions by the leave-one-out cross-validation (LOOCV) procedure. The results confirm the great potential of neural networks to guide ophthalmologists in choosing appropriate surgical candidates and their specific intracorneal rings by predicting post-implantation ocular features.

Vision-related quality of life among patients with keratoconus: a cross sectional study

Purpose

The present study aimed to evaluate the quality of life of keratoconus patients residing in Nablus city, Palestine. Furthermore, we investigated the possible correlation between Pentacam topographic indices and the quality of life of patients with keratoconus.

Methods

This cross-sectional study evaluated keratoconus patients at An-Najah University Hospital in 2019, diagnosed through clinical examination and corneal tomography. A control group was randomly selected from non-keratoconus patients with normal tomography. The NEI-VFQ-25 questionnaire was administered during face-to-face interviews to compare both groups. NEI-VFQ-25 assesses vision-related quality of life and is a validated tool.

Results

Keratoconus patients' quality of life is significantly impacted, mainly in near and distant vision, general vision, mental health, and social health, but not in general health, ocular pain, color vision, role difficulties, or dependency. Visual acuity is significantly affected in both eyes of keratoconus patients.

Conclusion

Patients with keratoconus exhibit a decreased quality of life related to vision, with physical, emotional, and social impairments demonstrated by the NEI-VFQ-25 when compared to controls. Since keratoconus patients are typically young adults in their productive years, understanding their concerns about their future is an important public health aspect that can aid in modifying their treatments. By addressing the specific needs of this patient population, healthcare providers can better support their long-term well-being and quality of life.

The prevalence of keratoconus in northern Poland: A cross-sectional study of patients from a primary healthcare practice

INTRODUCTION

Keratoconus is defined as central and/or paracentral corneal thinning and steepening with consequent irregular astigmatism. To date, no prospective study has reported its prevalence in Central Europe. This study aimed to evaluate the prevalence of keratoconus assessed with Scheimpflug imaging in a profile of general medicine practice in Poland.

METHODS

This cross-sectional study collected data by inviting all patients aged 10-80 years subscribed to a single general practitioner in the Elbląg area, Poland. Corneal measurements were performed using a rotating Scheimpflug corneal tomography system. Three masked examiners established the diagnosis of keratoconus in the right or left eye. Fleiss' kappa coefficient (κ) was used to qualitatively analyze the interexaminer agreement.

RESULTS

Of 1,705 patients invited to the study, 771 agreed to participate (45.2%). The mean age of the 728 patients (60.6% female and 39.4% male) with gradable images in at least one eye was 53.6 ± 16.5 years. All of the examiners classified the same four cases as keratoconus (0.549%, 549 per 100,000, 95% confidence interval 150 to 1,400 per 100,000), of which two were bilateral. Fleiss' kappa showed almost perfect agreement among the three examiners regarding the diagnostic decision (κ = 0.784, 95% confidence interval 0.750 to 0.817, p < 0.001). The keratoconus cases were all women (p = 0.106), aged 48, 69, 70, and 71 years old.

CONCLUSION

The prevalence of keratoconus in this area was higher than that previously demonstrated in many European countries. Underestimation of the prevalence has been postulated but never demonstrated.

Artificial intelligence-based stratification of demographic, ocular surface high-risk factors in progression of keratoconus

Purpose

The purpose of this study was to identify and analyze the clinical and ocular surface risk factors influencing the progression of keratoconus (KC) using an artificial intelligence (AI) model.

Methods

This was a prospective analysis in which 450 KC patients were included. We used the random forest (RF) classifier model from our previous study (which evaluated longitudinal changes in tomographic parameters to predict "progression" and "no progression") to classify these patients. Clinical and ocular surface risk factors were determined through a questionnaire, which included presence of eye rubbing, duration of indoor activity, usage of lubricants and immunomodulator topical medications, duration of computer use, hormonal disturbances, use of hand sanitizers, immunoglobulin E (IgE), and vitamins D and B12 from blood investigations. An AI model was then built to assess whether these risk factors were linked to the future progression versus no progression of KC. The area under the curve (AUC) and other metrics were evaluated.

Results

The tomographic AI model classified 322 eyes as progression and 128 eyes as no progression. Also, 76% of the cases that were classified as progression (from tomographic changes) were correctly predicted as progression and 67% of cases that were classified as no progression were predicted as no progression based on clinical risk factors at the first visit. IgE had the highest information gain, followed by presence of systemic allergies, vitamin D, and eye rubbing. The clinical risk factors AI model achieved an AUC of 0.812.

Conclusion

This study demonstrated the importance of using AI for risk stratification and profiling of patients based on clinical risk factors, which could impact the progression in KC eyes and help manage them better.

Biomechanical properties analysis of forme fruste keratoconus and subclinical keratoconus

PURPOSE

To analyze the biomechanical properties of the eye in patients with unilateral keratoconus with normal (forme fruste keratoconus [FFKC]) or abnormal topography (subclinical keratoconus [SKC]).

METHODS

This study included 153 eyes of 153 participants, including 95 eyes of patients with unilateral keratoconus, and 58 eyes of 58 healthy controls. Contralateral eyes with unilateral keratoconus were divided into two groups according to clinical manifestations and global consensus: FFKC (n = 30) and SKC (n = 65). The biomechanical characteristics were analyzed using non-parametric tests; further analysis thereof was performed after adjusting for confounding factors (i.e., intraocular pressure, age, and corneal thickness). Receiver operating characteristic curve (ROC) was used to analyze the ability of the biomechanical parameters to distinguish FFKC from SKC.

RESULTS

Statistically significant differences between the FFKC and SKC groups were found in 9 of the 18 corneal biomechanical parameters analyzed using non-parametric tests. After adjusting for confounding factors, the multivariate analysis still revealed significant statistical differences in A1-time (P = 0.017), integrated radius (IR) (P = 0.024), and tomographic and biomechanical index (TBI, P < 0.001) between the FFKC and SKC groups. Stiffness parameter at first applanation (SP-A1) (Area under ROC [AUROC] = 0.765) demonstrated the strongest distinguishing ability, except for TBI (AUROC = 0.858) and Corvis Biomechanical Index (AUROC = 0.849), however, there was no statistically significant difference in SP-A1 (P = 0.366) between FFKC and SKC.

CONCLUSIONS

Biomechanical parameters A1-time and IR have a high diversity between FFKC and SKC, besides TBI, and may reflect more subtle changes in corneal biomechanical properties (BPs) preceding SP-A1. The BPs of SKC are weaker than FFKC, which might be a basic and clue for the classification and diagnosis of the severity of early keratoconus in terms of biomechanics.

Visual Outcomes of Small-Incision Lenticule Extraction (SMILE) in Thin Corneas

We aimed to find out whether thin (≤500 μm) or normal (>500 μm, control) corneal thickness would impact efficacy and safety outcomes of small-incision lenticule extraction (SMILE). We retrospectively analyzed medical records of adult patients who had undergone SMILE. A total of 57 eyes were included in the “thin corneas” group and 180 eyes in the “control” group. At one month after surgery, rates of patients with uncorrected distance visual activity (UDVA) ≥ 0.8 were significantly higher in patients from the control group compared to the “thin corneas” group (87 vs. 71%, respectively p < 0.01), though rates were comparable at 3 months (87 vs. 76%, respectively, p > 0.05). SMILE had comparable safety in patients with thin and normal corneas. Procedure result predictability was comparable between groups. Regression analysis demonstrated that cap thickness impacted posterior corneal biomechanics, and the volume of removed tissue had a higher influence in patients with thin corneas. Moreover, an increase in cap thickness was associated with better final BCVA. Further study is needed for the evaluation of the impact of thin corneas on SMILE outcomes and planning. Our study also indicates that patients with thin corneas might require a different approach to nomogram calculation.

Childhood Vision Impairment and Refractive Error in Zimbabwe: A Hospital-based Retrospective Study

Background

The objective of this study was to determine the causes and distribution of vision impairment and refractive error among children in Zimbabwe.

Methods

A hospital-based retrospective cross-sectional study was conducted among children (3–16) who attended the Eye Institute, Harare, Zimbabwe, from January 2010 to December 2020. Patients' records were collated, and variables such as visual acuity, ocular morbidities, and vision impairment were analysed.

Results

During this time, 1038 children with mean age of 10.63 ± 3.54 years visited the facility. The majority of them were males (53.2%). Prior to treatment, 9.9% of the children had vision impairment which reduced to 3.5% after intervention. Uncorrected refractive error accounted for the majority of vision impairment (67.0%), followed by keratoconus (7.8%), corneal opacity/ulceration (6.8%), and amblyopia (6.8%), among other conditions. Astigmatism (60.6%) was the most prevalent type of refractive error followed by myopia (37.5%).

Conclusion

The prevalence of childhood vision impairment is higher than that found in similar hospital-based studies conducted in Africa. The most common reason for childhood vision impairment was uncorrected refractive error.

Repeatability of i.Profiler for measuring wavefront aberrations in healthy eyes

PURPOSE

To evaluate the repeatability of wavefront aberration measurements and the correlation between corneal aberration and pupil size in normal eyes using a wavefront-based autorefractor (i.Profiler^Plus; Carl Zeiss Vision, Germany).

METHODS

A prospective cross-sectional study. Wavefront aberrations, including spherical aberration (SA) (Z₄⁰), coma (Z₃^-1, Z₃¹), trefoil (Z₃^-3, Z₃³) and total higher-order aberrations (tHOA), were measured at different pupil diameters. The repeatability was evaluated using one-way ANOVA method, and statistical indicators including within-subject standard deviation (S_w), test-retest repeatability (TRT), and intra-class correlation coefficient (ICC). The correlations between corneal aberrations and pupil sizes were evaluated by Pearson correlation analysis.

RESULTS

A total of 96 healthy young volunteers were enrolled. Corneal and ocular higher-order aberrations (HOA) measured by i.Profiler showed S_w < 0.01 μm, TRT < 0.10 μm, ICC > 0.90. There was a linear positive correlation between the corneal HOA and pupil size. The correlation coefficient between SA and tHOA was the largest (r = 0.996, P < 0.001).

CONCLUSIONS

The measurements of wavefront aberrations by i.Profiler are highly repeatable. Corneal HOA was significantly dependent on pupil size. SA was the most influential aberration for visual quality in this study.

Keratoconus: An updated review

Keratoconus is a bilateral and asymmetric disease which results in progressive thinning and steeping of the cornea leading to irregular astigmatism and decreased visual acuity. Traditionally, the condition has been described as a noninflammatory disease; however, more recently it has been associated with ocular inflammation. Keratoconus normally develops in the second and third decades of life and progresses until the fourth decade. The condition affects all ethnicities and both sexes. The prevalence and incidence rates of keratoconus have been estimated to be between 0.2 and 4,790 per 100,000 persons and 1.5 and 25 cases per 100,000 persons/year, respectively, with highest rates typically occurring in 20- to 30-year-olds and Middle Eastern and Asian ethnicities. Progressive stromal thinning, rupture of the anterior limiting membrane, and subsequent ectasia of the central/paracentral cornea are the most commonly observed histopathological findings. A family history of keratoconus, eye rubbing, eczema, asthma, and allergy are risk factors for developing keratoconus. Detecting keratoconus in its earliest stages remains a challenge. Corneal topography is the primary diagnostic tool for keratoconus detection. In incipient cases, however, the use of a single parameter to diagnose keratoconus is insufficient, and in addition to corneal topography, corneal pachymetry and higher order aberration data are now commonly used. Keratoconus severity and progression may be classified based on morphological features and disease evolution, ocular signs, and index-based systems. Keratoconus treatment varies depending on disease severity and progression. Mild cases are typically treated with spectacles, moderate cases with contact lenses, while severe cases that cannot be managed with scleral contact lenses may require corneal surgery. Mild to moderate cases of progressive keratoconus may also be treated surgically, most commonly with corneal cross-linking. This article provides an updated review on the definition, epidemiology, histopathology, aetiology and pathogenesis, clinical features, detection, classification, and management and treatment strategies for keratoconus.

Anterior pituitary, sex hormones, and keratoconus: Beyond traditional targets

"The Diseases of the Horny-coat of The Eye", known today as keratoconus, is a progressive, multifactorial, non-inflammatory ectatic corneal disorder that is characterized by steepening (bulging) and thinning of the cornea, irregular astigmatism, myopia, and scarring that can cause devastating vision loss. The significant socioeconomic impact of the disease is immeasurable, as patients with keratoconus can have difficulties securing certain jobs or even joining the military. Despite the introduction of corneal crosslinking and improvements in scleral contact lens designs, corneal transplants remain the main surgical intervention for treating keratoconus refractory to medical therapy and visual rehabilitation. To-date, the etiology and pathogenesis of keratoconus remains unclear. Research studies have increased exponentially over the years, highlighting the clinical significance and international interest in this disease. Hormonal imbalances have been linked to keratoconus, both clinically and experimentally, with both sexes affected. However, it is unclear how (molecular/cellular signaling) or when (age/disease stage(s)) those hormones affect the keratoconic cornea. Previous studies have categorized the human cornea as an extragonadal tissue, showing modulation of the gonadotropins, specifically luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Studies herein provide new data (both in vitro and in vivo) to further delineate the role of hormones/gonadotropins in the keratoconus pathobiology, and propose the existence of a new axis named the Hypothalamic-Pituitary-Adrenal-Corneal (HPAC) axis.

Keratoconus Diagnostic and Treatment Algorithms Based on Machine-Learning Methods

The accurate diagnosis of keratoconus, especially in its early stages of development, allows one to utilise timely and proper treatment strategies for slowing the progression of the disease and provide visual rehabilitation. Various keratometry indices and classifications for quantifying the severity of keratoconus have been developed. Today, many of them involve the use of the latest methods of computer processing and data analysis. The main purpose of this work was to develop a machine-learning-based algorithm to precisely determine the stage of keratoconus, allowing optimal management of patients with this disease. A multicentre retrospective study was carried out to obtain a database of patients with keratoconus and to use machine-learning techniques such as principal component analysis and clustering. The created program allows for us to distinguish between a normal state; preclinical keratoconus; and stages 1, 2, 3 and 4 of the disease, with an accuracy in terms of the AUC of 0.95 to 1.00 based on keratotopographer readings, relative to the adapted Amsler–Krumeich algorithm. The predicted stage and additional diagnostic criteria were then used to create a standardised keratoconus management algorithm. We also developed a web-based interface for the algorithm, providing us the opportunity to use the software in a clinical environment.

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.

[Early diagnosis of keratoconus]

Keratoconus is morphologically associated with increasing deformation, thinning and scarring of the cornea. This functionally leads to refractive changes and visual deterioration. In the early stages there are often no clear clinical signs in the slit-lamp examination; however, confirming the diagnosis as early as possible is important in order to provide patients with an appropriate treatment. For the early diagnosis of keratoconus, various diagnostic devices have been introduced in recent years and decades. These include keratometry with reflection-based or elevation-based systems and optical coherence tomography. High-frequency ultrasound microscopy and corneal biomechanics can also be used to establish the diagnosis of keratoconus by the measurement of other parameters. The necessity and the available possibilities for early diagnosis of keratoconus are presented in more detail in this article.

Artificial Intelligence Efficiently Identifies Regional Differences in the Progression of Tomographic Parameters of Keratoconic Corneas

PURPOSE

To develop an artificial intelligence (AI) model to effectively assess local versus global progression of keratoconus using multiple tomographic parameters.

METHODS

This was a retrospective review of medical records of patients diagnosed as having keratoconus. A total of 1,884 Pentacam (Oculus Optikgeräte GmbH) scans of 366 eyes (296 patients) were analyzed. Based on an increase in maximum anterior curvature (Kmax), the eyes were classified as actual "progression" and "no progression." The corresponding changes in other Pentacam parameters were incorporated to train and cross-validate (five-fold) the AI models. Three AI models were trained (an increase in Kmax by A = 0.75 diopters [D], B = 1.00 D, and C = 1.25 D). The area under the curve (AUC), sensitivity, specificity, and classification accuracy, along with other metrics, were evaluated.

RESULTS

The AUC, sensitivity, specificity, and classification accuracy were 0.90, 85%, 82%, and 83%, respectively, for Model A; 0.91, 86%, 82%, and 88%, respectively, for Model B; and 0.93, 89%, 81%, and 91%, respectively, for Model C. All models also predicted that 60% to 62% of the actual progression eyes had concomitant progression-associated changes in the other Pentacam parameters (global progression). However, there was discordance between increase in Kmax and concomitant associated changes in the other parameters in 38.8% to 40% of the eyes (local progression).

CONCLUSIONS

The AI models identified the eyes where the increase in Kmax and corresponding progression-associated changes in the other parameters were in agreement. These eyes may require corneal cross-linking earlier than the rest. [J Refract Surg. 2021;37(4):240-248.].

Absence of the c.169+50delTAAACAG mutation of SOD1 gene in a sample of keratoconus patients in Brazilian population

OBJECTIVE

To determine the presence of the 7-bp deletion c.169+50delTAAACAG in intron 2 of Superoxide Dismutase-1 gene in keratoconic patients from the State of São Paulo, Brazil, which promotes splicing variations, resulting in non-functional Superoxide Dismutase-1 antioxidant proteins, which may damage the corneal structure.

RESULTS

A group of 35 keratoconic patients, from whom 35 peripheral blood samples and 58 samples of corneal fragments were evaluated, and a control group of 89 individuals, from whom 41 blood samples and 149 samples of corneal fragments were collected. After the amplification of DNA fragments by polymerase chain reaction, mutational screening analysis was performed by enzymatic digestion, followed by direct sequencing. The absence of the 7-bp c.169+50delTAAACAG mutation in intron 2 of Superoxide Dismutase-1 gene was detected in the analyzed subjects of the 2 groups, both in the cornea and peripheral blood samples. Then, according to our results, there is no involvement of c.169+50delTAAACAG deletion in the pathogenesis of keratoconus in this population, once it was not detected. But we emphasize that studies involving this deletion must be continued in an attempt to elucidate this issue.