Singlet oxygen formation during accelerated and hyperaccelerated corneal cross-linking: in vitro study

BACKGROUND: To evaluate the singlet oxygen (1 O2) production of oxygen assisted %0.1 riboflavin and ultraviolet-A (UVA) crosslinking therapy (with and without oxygen assistance), in combination with standard, accelerated and hyper-accelerated procedures via an important quantitive marker of 1 O2 which is the photo-oxidation of 1,3 diphenylisobenzofuran (DPBF). METHODS: %0.1 riboflavin-containing wells were irradiated with UVA light (365-nm wavelength) with or without 2-4-6-8 L/min oxygen flow assistance. Measurements of decrease in absorbance of DPBF were made in 30 mW (hyper-accelerated), 9 mW (accelerated), and 3 mW UV-A (standard) applications, and with additional 2-4-6-8 L/min oxygen flow in 30 mW and 2 L/min oxygen flow in 9 mW. A total of 8 different UV-A irradiance with and without oxygen supplementation groups were formed. RESULTS: 2 L/min oxygen assisted accelerated UV-A irradiance group has shown a greater decrease in DPBF absorbance compared to Dresden protocol. (p = 0.014) Also, Dresden protocol has shown a greater decrease in DPBF compared to all groups except accelerated crosslinking with 2 L/min oxygen. (p < 0.001) Oxygen assisted hyper-accelerated crosslinking groups were showed greater reduction in DPBF absorbance compared to standard crosslinking without oxygen groups. (p < 0.001). CONCLUSION: Oxygen supplementation may increase the singlet oxygen generation to the similar levels of Dresden Protocol’s in accelerated group. Also, more singlet oxygen generation with oxygen supplementation compared to standard UV-A application might be considered to be promising in terms of shortening the crosslinking therap

Choroidal and retinal vascular changes in retinal vein occlusion

Amaç: Bu çalışmada retinal ven tıkanıklığı (RVT) geçirmiş olgularda koroidal değişiklikleri değerlendirerek bu bulguların retinal vaskülarite ve diğer klinik özellikler ile ilişkisini incelemek amaçlanmıştır. Gereç ve Yöntem: Retinal ven tıkanıklığı nedeniyle takip edilen 64 olgu ve 34 sağlam kontrol olgusu çalışmaya dahil edildi. Çalışmaya dahil olan olguların optik koherens tomografi (OKT), EDI-OKT, optik koherens tomografi anjiyografi (OKT-A), rutin oftalmolojik muayene bulguları incelendi. Image J programı yardımıyla EDI-OKT üzerinden koroidal vasküler indeks (KVİ), Haller/Sattler oranı (H/S) ve OKT-A üzerinden koryokapillaris vaskülarite oranı (KVO) hesaplandı. Kontralateral gözler, hasta gözler ve kontrol gözlerinin KVİ, KVO ve H/S değerleri karşılaştırıldı. Bulgular: Hasta gözlerde hem kontralateral gruba hem de kontrol grubuna göre H/S oranının yüksek, KVO'nun ise düşük olduğu saptandı. (Hepsi için p<0,001) KVİ oranının RVT grubunda hem RVT kontralateral grubuna göre (p:0,001) hem de kontrol grubuna göre (p:<0,001) azalmış olduğu izlendi. Kontralateral grupta CVİ'nin kontrol grubuna göre daha düşük saptandı (p=0.035). Saptanabilen en önemli korelasyonlar görme keskinliği ile H/S oranı, KVİ ve KVO arasında idi. Sonuç: RVT olgularında yalnızca retinal vasküler değişiklikler değil KVI, H/S oranı ve KVO gibi parametrelerde de değişiklikler izlenmektedir. Bu değişiklikler ile klinik bulgular arasında ilişki olduğu görülmüştür. RVO'da koroidal değişiklikler ve klinik önemleri ile ilgili ileri çalışmalara gerek duyulmaktadır. Anahtar Kelimeler: Retinal Ven Tıkanıklığı, Koroidal Vasküler İndeks, Optik Koherens Tomografi Anjiyografi, Haller/Sattler Oranı, Koryokapillaris Vaskularite OranıPurpose: The aim of this study was to evaluate the choroidal changes and their relationship with retinal vasculature and clinical features of patients with retinal vein occlusion (RVO). Materials and Methods: Sixty four unilateral RVO cases and 34 healthy controls were included in the study. Optical coherence tomography (OCT), enhanced depth imaging optical coherence tomography (EDI-OCT), coherence tomography angiography (OCT-A) and routine ophthalmologic examination findings were evaluated. Choroidal vascular index (CVI), Haller/Sattler ratio (H/S) were calculated via the Image J software. Choriocapillaris vascularity ratio (CVR) was calculated via the Optovue OCT-A software. CVI, CVR and H/S ratio values of RVO eyes were compared with contralateral healthy (contralateral group) and control subject eyes (control group). Results: Compared to both contralateral and control groups, the H/S ratio was higher and the CVR was lower in the RVO eyes (p <0.001 for all). CVI was found to be decreased in the RVO group compared to the contralateral group (p: 0,001) and the control group (p: <0,001). The contralateral group also differed from the control group in terms of CVI (lower CVI in the contralateral group, p=0.035). The most prominent correlations were those between the visual acuity and H/S ratio, CVI and CVO. Conclusion: Choroidal parameters such as CVI, H/S ratio and CVR appear to be affected in RVO eyes. These changes appear to be related to clinical features of the diseased eyes. Further studies evaluating choroidal changes in RVO and their clinical implications are warranted. Keywords: Retinal Vein Occlusion, Choroidal Vascular Index, Choriocapillaris vascularity ratio, Haller/Sattler ratio, Optical Coherence Tomography Angiograph