A Case of Early Keratoconus Associated with Eye Rubbing in a Young Child.

INTRODUCTION: Keratoconus usually presents during puberty and is considered rare in young children. METHODS: Case report with clinical findings and computerized corneal tomography. RESULTS: We report the case of an 8-year-old girl with early bilateral keratoconus who presented with allergic conjunctivitis and persistent eye rubbing. Although our patient did not exhibit steep keratometry, early cones and inferotemporal thinnest corneal thicknesses were detected in both eyes using Scheimpflug imaging (Oculus GmbH Pentacam, Wetzlar, Germany). Belin/Ambrósio total D values were 1.85 on the right and 2.11 on the left. Improvement in best-corrected visual acuity was noted after treatment of allergic eye disease, and corneal tomographic findings remained stable 4 months after initial consult. CONCLUSION: This is a case of early diagnosed keratoconus in a young patient. Diagnosis of this condition in young children is challenging, as these patients are less likely to report visual complaints, and clinical examination is usually unremarkable. Keratoconus screening should be considered in children with atopy and eye rubbing behavior regardless of age, even in those with no other associated pathology and with negative family history.

The Proteins of Keratoconus: a Literature Review Exploring Their Contribution to the Pathophysiology of the Disease.

INTRODUCTION: Keratoconus (KC) is a complex, genetically heterogeneous multifactorial degenerative disorder characterized by corneal ectasia and thinning. Its incidence is approximately 1/2000-1/50,000 in the general population. KC is associated with moderate to high myopia and irregular astigmatism, resulting in severe visual impairment. KC structural abnormalities primarily relate to the weakening of the corneal collagen. Their understanding is crucial and could contribute to effective management of the disease, such as with the aid of corneal cross-linking (CXL). The present article critically reviews the proteins involved in the pathophysiology of KC, with particular emphasis on the characteristics of collagen that pertain to CXL. METHODS: PubMed, MEDLINE, Google Scholar and GeneCards databases were screened for relevant articles published in English between January 2006 and June 2018. Keyword combinations of the words "keratoconus," "risk factor(s)," "genetics," "genes," "genetic association(s)," "proteins", "collagen" and "cornea'' were used. In total, 272 articles were retrieved, reviewed and selected, with greater weight placed on more recently published evidence. Based on the reviewed literature, an attempt was made to tabulate the up- and down-regulation of genes involved in KC and their protein products and to delineate the mechanisms involved in CXL. RESULTS: A total of 117 proteins and protein classes have been implicated in the pathogenesis and pathophysiology of KC. These have been tabulated in seven distinct tables according to their gene coding, their biochemistry and their metabolic control. CONCLUSION: The pathogenesis and pathophysiology of KC remain enigmatic. Emerging evidence has improved our understanding of the molecular characteristics of KC and could further improve the success rate of CXL therapies.

A Modified Surgical Technique to Treat Strabismus in Complete Sixth Nerve Palsy.

INTRODUCTION: A lot of different techniques have been proposed in order to manage abduction limitation secondary to sixth nerve palsy; however, anterior segment ischemia remains a concern. The aim of this study was to evaluate the results of augmented vertical recti muscle transposition (VRT) with partial recession of medial rectus muscle (MR) for complete, chronic sixth nerve palsy, a new modified technique that could also minimize the risk for anterior segment ischemia (ASI). METHODS: In this nonrandomized 8-year (2009-2017) retrospective review, 20 patients with complete sixth nerve palsy and contracted MR were enrolled. All of them underwent augmented VRT and partial recession of the MR, following a new proposed surgical technique. Only the central part of the MR tendon and belly was recessed by 6.5 mm, leaving 1.5 mm of the upper pole and 1.5 mm of the lower pole of the muscle intact, preserving the circulation of two anterior ciliary arteries. RESULTS: Twenty patients with a mean age of 43 years (range 12-71), all unilateral cases, were enrolled in this study. The mean preoperative deviation was 64.25 ± 10.9 prism diopters (PD) base out (range 50 to 90). In 17 cases (88%), the postoperative deviation was within 10 PD of orthotropia. Two patients (10%) had residual esotropia (15 PD and 20 PD, respectively), and one patient (5%) had 10 PD of hypotropia. The mean preoperative abduction limitation of -5.9 improved to -3.1 (p < 0.0001). None of the cases presented with ASI (success rate 100%). CONCLUSION: Partial recession of the MR preserving the two anterior ciliary arteries (Kozeis modified technique) with augmented vertical recti muscle transposition is an effective procedure, with a high success rate and is probably less risky for ASI.

Genetic Aspects of Keratoconus: A Literature Review Exploring Potential Genetic Contributions and Possible Genetic Relationships with Comorbidities.

INTRODUCTION: Keratoconus (KC) is a complex, genetically heterogeneous, multifactorial degenerative disorder that is accompanied by corneal ectasia which usually progresses asymmetrically. With an incidence of approximately 1 per 2000 and 2 cases per 100,000 population presenting annually, KC follows an autosomal recessive or dominant pattern of inheritance and is, apparently, associated with genes that interact with environmental, genetic, and/or other factors. This is an important consideration in refractive surgery in the case of familial KC, given the association of KC with other genetic disorders and the imbalance between dizygotic twins. The present review attempts to identify the genetic loci contributing to the different KC clinical presentations and relate them to the common genetically determined comorbidities associated with KC. METHODS: The PubMed, MEDLINE, Google Scholar, and GeneCards databases were screened for KC-related articles published in English between January 2006 and November 2017. Keyword combinations of "keratoconus," "risk factor(s)," "genetics," "genes," "genetic association(s)," and "cornea" were used. In total, 217 articles were retrieved and analyzed, with greater weight placed on the more recent literature. Further bibliographic research based on the 217 articles revealed another 124 relevant articles that were included in this review. Using the reviewed literature, an attempt was made to correlate genes and genetic risk factors with KC characteristics and genetically related comorbidities associated with KC based on genome-wide association studies, family-based linkage analysis, and candidate-gene approaches. RESULTS: An association matrix between known KC-related genes and KC symptoms and/or clinical signs together with an association matrix between identified KC genes and genetically related KC comorbidities/syndromes were constructed. CONCLUSION: Twenty-four genes were identified as potential contributors to KC and 49 KC-related comorbidities/syndromes were found. More than 85% of the known KC-related genes are involved in glaucoma, Down syndrome, connective tissue disorders, endothelial dystrophy, posterior polymorphous corneal dystrophy, and cataract.