Increased systemic oxidative stress in patients with keratoconus

Abstract

Purpose To establish the effect of systemic oxidative stress on the pathogenesis of keratoconus by measuring serum total oxidant status (TOS) and total antioxidant status (TAS) in patients with keratoconus. Methods Twenty-five patients with keratoconus (keratoconus group) and 25 age-sex-matched healthy subjects (control group) were enrolled in the study. Exclusion criteria were smoking habit, history of any other corneal pathology, systemic disease or inflammation, and current antioxidant or anti-inflammatory therapies. All participants underwent a detailed ophthalmological examination and corneal topography. Serum samples were obtained from all participants. Oxidative stress markers (TAS and TOS) were measured using a commercial kit and oxidative stress index (OSI) was calculated. Results The study comprised 25 patients with keratoconus (mean age of 26.4 ± 1.7 years) and 25 healthy control subjects (mean age of 26.6 ± 1.7 years) (P40.05). The serum TOS and OSI values were significantly higher in patients with keratoconus compared with those of the controls (P ¼ 0.036 and 0.037, respectively). However, serum TAS did not show significant difference between the keratoconus and control groups (P ¼ 0.497). Conclusions The higher levels of serum oxidant status and OSI in patients with keratoconus suggest that systemic oxidative stress might be involved in the pathogenesis of keratoconus.

Keratoconus: an inflammatory disorder?

“…112,113,119,120 Increasing evidence supports the fact that thinning and ectasia of the cornea are related to a degraded extracellular matrix involving inflammatory events (mainly increased levels of MMP-9, IL-6, and TNF-α) 10,[12][13][14]67,91 and increased oxidative stress. [143][144][145][146] However, the precise role of each of the identified molecular factors still needs to be defined in further studies.…”

“…However, more recently Toprak et al 145 found that serum total oxidant status and oxidative stress index values were significantly higher in patients with keratoconus compared with those of the controls, suggesting that systemic oxidative stress might be involved in the pathogenesis of the condition. The recent findings by Karaca et al 104 with regard to NLR, already mentioned, also seem to support a relationship between the progression of keratoconus and increased systemic inflammatory response.…”

Cytokine Expression in Keratoconus and its Corneal Microenvironment: A Systematic Review

“…Currently, KC is considered to be a multifactorial corneal disorder caused by the sophisticated interaction of several environmental (eye-rubbing, contact lens wear) and endogenous factors leading to systemic and corneal oxidative stress by hypersensitive response to oxidative stressors that involves mitochondrial dysfunction and mtDNA damage in genetically susceptible individuals. [3][4][5][6] Prolonged eye-rubbing alone is reported as an independent risk factor for the development of KC, with abundant clinical evidence that vigorous eye-rubbing can lead to de novo development of KC. 7,8 However, eye-rubbing without overt KC development will not be clinically recognized if the patient does not seek medical attention, and not all patients with KC will exhibit a history of eye-rubbing.…”

“…For example, systemic inflammation monitored via the neutrophil-tolymphocyte ratio was recently associated with progressive KC125 , and systemic oxidative stress has been reported in KC patients 3. Increased frequency of neutrophils indicates proinflammatory conditions, and neutrophils are associated with the activation of MMPs, which have been found to be elevated in KC 125.…”

Clinical Evidence of Decreased Iris Resistance in Patients With Keratoconus

“…In contrast, there are evidences substantiating the fact that weakening of the cornea might result from localized mechanical or oxidative stress. 9,10 Neodymium:yttrium-aluminum-garnet (Nd:YAG) laser peripheral iridotomy (LPI) is a routine procedure before the implantation of phakic intraocular lenses (PIOLs), which is usually performed 1 week before the surgery. Dark-brown thick irises, which are more common in the Asian population, may need a higher amount of energy to achieve patent LPI.…”