Impact of classifying keratoconus location based on keratometry or pachymetry on progression parameters.

BACKGROUND: This study sought to assess the impact of classifying keratoconus location based on thinnest pachymetry or maximum keratometry (Kmax) on progression parameters after corneal crosslinking (CXL). METHODS: In this observational study, patients were followed up at one, three, six and 12 months after CXL. All patients underwent visual acuity, Scheimpflug tomography and slitlamp assessment at all follow-ups. Keratoconus was classified as central, paracentral and peripheral based on X and Y co-ordinates of either thinnest pachymetry (Group 1) or Kmax (Group 2). Progression parameters Kmax, ABCD grading, anterior, posterior and total wavefront (WF) aberrations were compared between the groups. RESULTS: Fifty-two eyes (43 patients) were classified into Groups 1 and 2: there were 82.8 per cent, 13.4 per cent, 3.8 per cent and 42.3 per cent, 38.4 per cent, 19.2 per cent central, paracentral and peripheral cones respectively. Central cones: Group 1: 'C' decreased after three months, Kmax, 'A', anterior and total WF decreased after six months. Group 2: Kmax, anterior and total WF decreased after three months, 'A' decreased at 12 months, whereas 'C' increased from three months. Paracentral cones: Group 1: no significant changes. Group 2: Kmax and 'A' decreased after six months, 'C' increased after three months. Peripheral cones: Group 1: no significant changes. Group 2: 'C' increased only at one month. CONCLUSION: Thinnest pachymetry and Kmax should not be used interchangeably when categorising keratoconus. Although keratoconus may have thin cornea centrally, the Kmax may not be central. For the majority of parameters considered for monitoring progression, changes were noticed earlier when the keratoconus was classified based on Kmax.

Corneal Cross-Linking: An Example of Photoinduced Polymerization as a Treatment Modality in Keratoconus.

The cornea is one of the principal refractive elements in the human eye and plays a crucial role in the process of vision. Keratoconus is the most common corneal dystrophy, found mostly among young adults. It is characterized by a reduced number of collagen cross-links in the corneal stroma, resulting in reduced biomechanical stability and an abnormal shape of the cornea. These changes lead to progressive myopia, corneal thinning, central scarring and irregular astigmatism, causing severely impaired vision. Hard contact lenses, photorefractive keratectomy or intracorneal rings are the most common treatment options for refractive error caused by keratoconus. However, these techniques do not treat the underlying cause of the corneal ectasia and therefore are not able to stop the progression of the disease. Riboflavin photoinduced polymerization of corneal collagen, also known as corneal cross-linking (CXL), has been introduced as the first therapy which, by stabilizing the structure of the cornea, prevents the progression of keratoconus. It stiffens the cornea using the photo-sensitizer riboflavin in combination with ultraviolet irradiation. This is a current review of the CXL procedure as a therapy for keratoconus, which relies on photoinduced polymerization of human tissue. We have focused on its biomechanical and physiological influences on the human cornea and have reviewed the previous and current biochemical theories behind cross-linking reactions in the cornea.

Giant cell arteritis incidence: analysis by season and year in mid-Atlantic United States.

BACKGROUND: Evaluate the incidence of biopsy-proven giant cell arteritis for seasonal or annual variability in the Mid-Atlantic United States. DESIGN: Retrospective chart review of all patients undergoing temporal artery biopsy from 1994 to 2011. PARTICIPANTS: The charts of 744 patients were reviewed, and 215 patients were diagnosed with giant cell arteritis based on positive temporal artery biopsy results. METHODS: All results between 1994 and 2011 were reviewed. Giant cell arteritis incidence data were evaluated by year, season and month for any trends or cyclic patterns. MAIN OUTCOME MEASURE: Incidence of biopsy-proven giant cell arteritis. RESULTS: The majority of patients were female (74%) and over the age of 60 (98.6%). The diagnosis of biopsy-proven giant cell arteritis was found in 215 of 744 (28.9%) patients. The incidence of biopsy-proven giant cell arteritis by year varied, with the peak incidence in 1996. The monthly incidence peaked in July and had a trough in October. However, Poisson regression analysis did not show any statistically significant trend over time or cyclic pattern to the incidence by year, season or month. CONCLUSIONS: The incidence of biopsy-proven giant cell arteritis in the population studied did not have any significant cyclic pattern over the last 17 years. The highest incidence by month was noted in July with a trough in October. However, this was not a significant pattern by month or season to support infectious or periodic environmental factors inciting giant cell arteritis.

[Leber's hereditary optic neuropathy--two case reports]. / Dziedziczna neuropatia nerwu wzrokowego Lebera--opis dwóch przypadków.

AIM: The aim of the article is to present 2 cases of LHON revealed in cousins (patients' mothers were sisters). MATERIAL AND METHODS: They were both diagnosed in the Molecular Medicine Faculty and Department of Ophthalmology, Medical University of Wroclaw. RESULTS: Three of the most popular mutations characteristic for Leber's hereditary optic neuropathy were negative in both patients. CONCLUSION: The patients might have some rare, wild or unidentified mutations. Leber's hereditary optic neuropathy, mtDNA, LHON.