Electrophysiological effects of hyperbaric oxygen treatment on the healthy retina.

PURPOSE: The study aimed to investigate the electrophysiological effects of hyperbaric oxygen treatment (HBOT) on the retina after ten sessions in healthy eyes. METHODS: This prospective, interventional study evaluated forty eyes of twenty patients who were treated with HBOT of ten sessions with the diagnosis of an extraocular health problem. All patients underwent a complete ophthalmologic examination, including assessments of best-corrected visual acuity (BCVA), slit-lamp and pupil-dilated fundus examinations, full-field electroretinography (ffERG) measurements before and after HBOT within 24 h of the 10th session. The ffERG was recorded according to the International Society for Clinical Electrophysiology of Vision protocol using the RETI-port system. RESULTS: The mean age of patients was 40.5 years ranging from 20 to 59 years. Thirteen patients were administered HBOT for avascular necrosis, six patients for sudden hearing loss, and one patient for chronic osteomyelitis of the vertebra. BCVA acuity was 20/20 in all eyes. The mean spherical refractive was 0.56 dioptre (D), and the mean cylindrical refractive error was 0.75 D. Dark-adapted b-wave amplitude in 3.0 ERG was the only variable for the b-wave that showed a statistically significant decrease (p = 0.017). The amplitude of the a-waves in dark-adapted 10.0 ERG and light-adapted 3.0 ERG reduced significantly (p = 0.024, p = 0.025). The amplitude of N 1-P 1 in light-adapted 30 Hz Flicker ERG also demonstrated a statistically significant decrease (p = 0.011). Implicit times did not differ significantly in any of the ffERG data (p > 0.05). CONCLUSIONS: HBOT caused the deterioration of a-wave and b-wave amplitudes in ffERG after ten treatment sessions. The results showed that photoreceptors were adversely affected in the short term after HBOT treatment.

The effect of hyperbaric oxygen therapy on retina, choroidal thickness, and choroidal vascularity index.

PURPOSE: To determine the acute and cumulative effect of hyperbaric oxygen therapy (HBOT) on retina and choroid tissue in healthy eyes. MATERIAL AND METHODS: Thirty-five subjects who were planned to undergo HBOT for non-ophthalmologic indications comprised the population of this prospective study. Central macular thickness (CMT), retinal nerve fiber layer (RNFL), and choroidal thickness (CT) (3 points: subfoveal area, 500 µm nasal and fovea temporal) were measured using spectral-domain optical coherence tomography (SD-OCT) before HBOT and half an hour after the 1st and 20th sessions of HBOT. The subfoveal choroidal area was segmented using ImageJ software with the binarization technique on enhanced depth imaging (EDI) OCT images. Choroidal area (CA), luminal area (LA), and stromal area (SA) were calculated. Choroidal vascularity index (CVI) was determined as the ratio between LA and CA. RESULTS: The right eyes of 35 patients aged between 22 and 59 years were enrolled in the study. The mean CMT values of the patients were 259.36 ± 22.31 µm, 256.94 ± 22.72 µm, and 254.58 ± 23.02 µm before HBOT, after the 1st session, and after the 20th session, respectively. The change in CMT values before and after HBOT was statistically significant (p=0.001). When the patients' RNFL, CT, CA, SA, LA, and CVI changes before and after the HBOT were examined, no statistically significant difference was found (p>0.05). CONCLUSIONS: Our study jointly evaluates the effect of HBOT on the vascular and stromal components of the choroid and macula in healthy eyes. Due to its thinning effect on the macula, it can be preferred as an adjunctive and facilitating treatment option in addition to current treatments in patients with macular edema due to retinal vascular disorders.

Efficiency of Ozone Therapy in a Rat Model of Experimental Uveitis.

PURPOSE: To investigate efficiency of ozone therapy in uveitis. METHODS: A total of 24 albino Wistar rats were randomly assigned to four groups (n = 6); (a) control group; (b) sham group; (c) infliximab treatment group; (d) ozone therapy group. Vitreous haze scores of all groups were evaluated. Vitreous cytokine levels (TNF-α, IL-1, IL-6) measured by ELISA and eyes were enucleated for histopathologic examination. RESULTS: According to vitreous haze scores, there was statistically significant inflammation in Group (b) compared with Group (a), and there was less inflammation in infliximab and ozone groups compared with Group (b) (p < 0.05). Cytokine levels in infliximab and ozone groups were lower but not statistically significant when compared with Group (b) (p > 0.05). There was significantly less inflammation in histopathologic examination in treatment groups when compared with the sham group (p < 0.05). CONCLUSIONS: Clinical and histopathologic examination results indicate that systemic application of ozone may be efficient in the treatment of uveitis.

The efficacy of hyperbaric oxygen for the treatment of experimental uveitis induced in rabbits.

OBJECTIVE: The aim of the present study was to examine the efficacy of hyperbaric oxygen (HBO) therapy in the treatment of experimental uveitis induced in rabbits. It was hypothesized that HBO therapy improves the regression of experimental uveitis induced in rabbits. RESEARCH DESIGN AND METHODS: An experimental animal study was conducted on 48 rabbits (48 right eyes of these rabbits) to evaluate the effects of HBO therapy on endotoxin-induced acute anterior uveitis in rabbits. To induce acute anterior uveitis, Salmonella typhimurium lipopolysaccharide endotoxin (LPS) was intravitreally injected into the right eyes of the rabbits. The animals were randomly assigned to five groups. No treatment was given to the rabbits in Group A. Prednisolone acetate was topically administered to the rabbits in Group B. Methylprednisolone acetate was administered by anterior subtenon injection to the rabbits in Group C four hours after LPS application. HBO therapy was administered to the rabbits in Group D. Both HBO therapy and anterior subtenon injection of methylprednisolone therapy were administered to the rabbits in Group E. To compare the effects of the different therapies on the progression of endotoxin-induced uveitis, examinations including clinical scoring of anterior uveitis, microscopic examination of aspirated aqueous humor for inflammatory responses, and aqueous protein level assessment were performed once a day after LPS injection. RESULTS: There was a statistically significant difference between the control group (Group A) and other groups (Groups B-E) with respect to the number of inflammatory cells and protein levels in the aqueous one and three days after LPS injection (p < 0.05), indicating that the treatments resulted in less inflammation in Groups B-E compared to Group A. Moreover, there was no statistically significant difference between Groups B and C, Groups B and D, Groups B and E, Groups C and D, and Groups C and E with regard to the number of inflammatory cells in the aqueous at Day 1 after LPS injection (p > 0.05). In addition, Groups B and C and Groups B and D were comparable with regard to cell counts at Day 3 (p > 0.05), showing that HBO was comparable to corticosteroids in reducing inflammation. The differences between Groups B and E and Groups C and E were significant with regard to aqueous cell counts at Day 3 (p < 0.05), showing that HBO plus steroid was more effective than steroids alone. CONCLUSION: The intensity of ocular inflammation in the group receiving HBO therapy combined with anterior subtenon injection of methylprednisolone therapy was lower than in the other groups. We also demonstrated that HBO therapy was an effective therapeutic modality for the treatment of experimental uveitis induced in rabbits with an efficacy comparable to that of corticosteroids. Moreover, HBO plus steroid was superior to steroids alone in reducing inflammation.