exudates and Keratoconus

Keratoconus is an ocular degeneration characterized by the thinning of corneal stroma that may lead to varying degrees of myopia and visual impairment. Genetic factors have been reported in the pathology of keratoconus where Asians have a higher incidence, earlier onset, and undergo earlier corneal grafts compared to Caucasians. The visual system homeobox 1 (VSX1) gene forms part of a paired-like homeodomain transcription factor which is responsible for ocular development. The gene was marked as a candidate in genetic studies of keratoconus in various populations. Single nucleotide polymorphisms (SNPs) in the VSX1 gene have been reported to be associated with keratoconus. The detection of the SNPs involves DNA amplification of the VSX1 gene followed by genomic sequencing. Thus, the objective of this study aims to establish sensitive and accurate screening protocols for the molecular characterization of VSX1 polymorphisms.. Keratoconic (n = 74) and control subjects (n = 96) were recruited based on clinical diagnostic tests and selection criteria. DNA extracted from the blood samples was used to genotype VSX1 polymorphisms. In-house designed primers and optimization of PCR conditions were carried out to amplify exons 1 and 3 of the VSX1 gene. PCR conditions including percentage GC content, melting temperatures, and differences in melting temperatures of primers were evaluated to produce sensitive and specific DNA amplifications.. Genotyping was successfully carried out in 4 exons of the VSX1 gene. Primer annealing temperatures were observed to be crucial in enhancing PCR sensitivity and specificity. Annealing temperatures were carefully evaluated to produce increased specificity, yet not allowing sensitivity to be compromised. In addition, exon 1 of the VSX1 gene was amplified using 2 different sets of primers to produce 2 smaller amplified products with absence of non-specific bands. DNA amplification of exons 1 and 3 consistently showed single band products which were successfully sequenced to yield reproducible data.. The use of in-house designed primers and optimized PCR conditions allowed sensitive and specific DNA amplifications that produced distinct single bands. The in-house designed primers and DNA amplification protocols established in this study provide an addition to the current repertoire of primers for accurate molecular characterization of VSX1 gene polymorphisms in keratoconus research.

Topics: DNA Primers; Eye Proteins; Genes, Homeobox; Genetic Testing; Homeodomain Proteins; Humans; Keratoconus; Malaysia; Nucleic Acid Amplification Techniques

To evaluate corneal thickness and volume in subclinical and clinical keratoconus in Asian population with the aim of discriminating between normal and ectatic cornea. Eyes were placed into one of the following three groups: normal, subclinical, and mild-moderate keratoconus. Pentacam Scheimpflug imaging (Oculus Inc., Wetzlar, Germany) was performed for each participant to record thinnest corneal thickness, central corneal thickness, corneal volume (CV), peripheral corneal thickness (PCT) and percentage thickness increase (PTI) at 2, 4, 6, and 8 mm. The data were exported to SPSS for statistical analysis. Subjects comprised 52 normal, 15 subclinical keratoconus, and 32 mild-moderate clinical keratoconus eyes. Our results indicated that corneal thickness (CT) distribution, PTI, and CV in normal eyes were significantly different compared with subclinical and clinical keratoconus (P < .05). Overall, subclinical group exhibited lower CT distribution and volume, and higher PTI in comparison with normal eyes. However, they showed higher CT distribution and volume, and lower PTI compared with keratoconus group. In addition, there was a smaller change in PCT and PTI from the thinnest point of the cornea to the periphery. The results of the present study indicate that CT parameters and CV were significantly different in normal versus subclinical group and in normal versus keratoconus group. These findings could help clinicians to better discriminate between normal and ectatic cornea.

Topics: Adolescent; Adult; Asian People; Cornea; Corneal Topography; Cross-Sectional Studies; Diagnosis, Differential; Female; Humans; Keratoconus; Malaysia; Male; Photography; Retrospective Studies; Young Adult

To assess changes in anterior segment parameters of keratoconus eyes at different stages of the disease in a sample of the Asian population.. Files of 32 patients (48 eyes) diagnosed as clinical keratoconus were assessed and the following parameters noted: central corneal thickness (CCT), thinnest corneal thickness (TCT), location of thinnest pachymetry, anterior chamber depth (ACD) at the centre from posterior corneal surface, ACD at 1, 2 and 3mm inferior-paracentral, ACD at thinnest pachymetry, anterior chamber volume (ACV) and anterior chamber angle (ACA). For analysis, keratoconus eyes were classified into 3 subgroups according to mean keratometry readings (mild: K≤47.0D, moderate: 47.0

Topics: Adolescent; Adult; Anterior Eye Segment; Comorbidity; Corneal Topography; Female; Humans; Keratoconus; Malaysia; Male; Refractive Errors; Retrospective Studies; Young Adult

To evaluate tears of newly diagnosed keratoconus patients attending the Optometry clinic in Malaysia and to compare this with tears of normal myopic subjects.. The ocular surface of newly diagnosed keratoconus patients were evaluated using tear break up time (TBUT) test, non invasive tear break up time test (NIBUT) and Schirmer test. Twenty keratoconus patients (40 eyes) and 40 normal subjects (80 eyes) participated in this study.. Significantly lower TBUT and NIBUT values were found in keratoconus patients than normal control subjects (p<0.05). Mean TBUT and NIBUT for keratoconus patients were 3.99±1.69s and 7.03±3.48s and for normal subjects were 7.24±4.39s and 13.67±10.81s respectively. However, no significant difference was detected in Schirmer test values. Mean values of Schirmer tests I and II for keratoconus patients were 20.52±10.66mm and 10.71±10.43mm and for normals were 23.83±11.34mm and 13.27±8.28mm accordingly.. It was concluded from this study that keratoconus patients have poor tear stability which need to be considered appropriately during management of the patients.

Topics: Humans; Keratoconus; Malaysia; Tears