Alterations In Corneal Thickness Research Articles

Association of Birth Weight with Central and Peripheral Corneal Thickness in Adulthood-Results from the Population-Based German Gutenberg Health Study.

Purpose: Low birth weight (BW) is associated with altered ocular geometry such as a steeper corneal shape in adulthood. However, it is unclear whether low birth weight affects corneal thickness development in the center or periphery in adulthood which may contribute to ocular disease. The purpose of this study was to investigate corneal thickness in former low birth weight individuals in adulthood. Methods: The German Gutenberg Health Study is a prospective, population-based study in which every participant (age range 40–80 years) was measured with Scheimpflug imaging (Pentacam HR, Oculus Optikgeräte GmbH, Wetzlar, Germany). BW was collected by self-reports. The relationship between birth weight and corneal thickness at different locations were assessed. Linear regression models were carried out including uni- and multivariable analyses with adjustment for age, sex, mean corneal radius, and white-to-white distance. Main outcome measures were corneal thickness at the apex, at the pupil center, and at the corneal periphery. Results: Overall, 5657 participants were successfully measured (3019 females, aged 56.0 ± 10.3 years). In multivariable analyses a lower BW was associated with a thinner corneal thickness at the apex (B = 1.71 µm/500 g, p < 0.001) and at the pupil (B = 1.69 µm/500 g, p < 0.001). These effects diminished towards the corneal periphery resulting in no differences in the perilimbal regions. Conclusion: The present study provides evidence that lower birth weight goes along with corneal thickness alterations even into adult ages of 40 to 80 years. Thinner measurements of the cornea were particularly found in the corneal center and diminished in the periphery. This indicates that there may be fetal origins affecting corneal thickness development particularly in the corneal center.

BCLA CLEAR - Orthokeratology

Orthokeratology (ortho-k) is the process of deliberately reshaping the anterior cornea by utilising specialty contact lenses to temporarily and reversibly reduce refractive error after lens removal. Modern ortho-k utilises reverse geometry lens designs, made with highly oxygen permeable rigid materials, worn overnight to reshape the anterior cornea and provide temporary correction of refractive error. More recently, ortho-k has been extensively used to slow the progression of myopia in children.This report reviews the practice of ortho-k, including its history, mechanisms of refractive and ocular changes, current use in the correction of myopia, astigmatism, hyperopia, and presbyopia, and standard of care. Suitable candidates for ortho-k are described, along with the fitting process, factors impacting success, and the potential options for using newer lens designs. Ocular changes associated with ortho-k, such as alterations in corneal thickness, development of microcysts, pigmented arcs, and fibrillary lines are reviewed. The safety of ortho-k is extensively reviewed, along with an overview of non-compliant behaviours and appropriate disinfection regimens. Finally, the role of ortho-k in myopia management for children is discussed in terms of efficacy, safety, and potential mechanisms of myopia control, including the impact of factors such as initial fitting age, baseline refractive error, the role of peripheral defocus, higher order aberrations, pupil size, and treatment zone size.

Ocular findings in Quarter Horses with hereditary equine regional dermal asthenia

To compare ocular structures of Quarter Horses homozygous for hereditary equine regional dermal asthenia (HERDA) with those of Quarter Horses not affected by HERDA (control horses) and to determine the frequency of new corneal ulcers for horses with and without HERDA during a 4-year period. Cohort study of ocular structures and retrospective case series of horses with and without HERDA. The cohort portion of the study involved 10 Quarter Horses with HERDA and 10 Quarter Horses without HERDA; the retrospective case series involved 28 horses with HERDA and 291 horses without HERDA. Ophthalmic examinations, Schirmer tear tests, tonometry, corneal pachymetry, histologic examinations, and scanning electron microscopy (SEM) were performed in cohorts of Quarter Horses with and without HERDA. Records were reviewed to determine the incidence of corneal ulcers in horses with and without HERDA during a 4-year period. Corneal thickness of horses with HERDA was significantly less than that of control horses, but tear production of horses with HERDA was significantly greater than that of control horses. Results of SEM revealed zones of disorganized, haphazardly arranged collagen fibrils in corneas of horses with HERDA that were not evident in corneas of control horses. The incidence of corneal ulcers was significantly greater for horses with HERDA than for horses without HERDA during the 4-year period. Alterations in corneal thickness, arrangement of collagen fibers, and incidence of corneal ulcers indicated that abnormalities in horses with HERDA were not limited to the skin.

Central Corneal Thickness Measurement in Clinical Practice

To determine if a single measurement of central corneal thickness (CCT) is an adequate sample to aid in glaucoma risk assessment in clinical practice. Central corneal thickness was measured by ultrasound pachymetry (mean of 15 measurements for each eye) on two separate occasions at least one month apart (range, 33 to 610 days). Eyes with a history of prior incisional surgery or corneal pathology were excluded. Ninety-eight eyes of 98 patients (43 male, 55 female) were enrolled. Mean age was 61.2 +/- 15.5 years. Mean inter-test period was 276 +/- 124 days. No significant difference in mean CCT was observed between the two visits (549 +/- 41 microm versus 548 +/- 42 microm, P = 0.4, two-tailed, paired t test). Measured CCT values differed by more than 20 microm in 20 eyes (20.4%), whereas CCT difference of at least 40 microm was seen in 5 eyes (5.1%). There was no correlation between the measured or absolute difference in CCT and IOP (r = -0.016, P > 0.43), inter-test time period (r = 0.072, P > 0.23), and glaucoma diagnosis. Central corneal thickness measurements in this study differed by at least 20 microm in 20% of eyes. This has important implications for risk assessment, management, and follow-up of patients with glaucoma and related disorders. Factors affecting CCT measurement, such as examiner error or true alterations in corneal thickness, require continued investigation.