Intravitreal Bevacizumab Alone or Combined with Macular Laser Photocoagulation for Recurrent or Persistent Macular Edema Secondary to Branch Retinal Vein Occlusion

Background. To evaluate the efficacy of intravitreal bevacizumab (IVB) injection with or without macular laser photocoagulation (MLP) for recurrent or persistent macular edema (ME) secondary to branch retinal vein occlusion (BRVO). Methods. Thirty-four eyes underwent IVB injection for ME secondary to BRVO as a primary treatment. Twenty of the 34 eyes experienced recurrent or persistent ME after the first IVB. Nine of the 20 eyes (Group 1) were retreated with IVB combined with MLP. The remaining 11 eyes (Group 2) were retreated with IVB alone. Results. In Group 1, the postoperative best corrected visual acuity (BCVA) improved compared with the preoperative value at all follow-up visits, although no statistically significant improvement was observed at 6 months. In contrast, BCVA significantly improved from 0.53 to 0.40 at 6 months (P<0.05) in Group 2. Conclusion. Combined therapy tended to have a smaller effect on visual acuity compared with IVB monotherapy

Estimation of Effective Day Length at Any Light Intensity Using Solar Radiation Data

The influence of day length on living creatures differs with the photosensitivity of the creature; however, the possible sunshine duration (N0) might be an inadequate index of the photoperiod for creatures with low light sensitivity. To address this issue, the authors tried to estimate the effective day length, i.e., the duration of the photoperiod that exceeds a certain threshold of light intensity. Continual global solar radiation observation data were gathered from the baseline surface radiation network (BSRN) of 18 sites from 2004 to 2007 and were converted to illuminance data using a luminous efficiency model. The monthly average of daily photoperiods exceeding each defined intensity (1 lx, 300 lx, … 20,000 lx) were calculated [defined as Ne(lux)]. The relationships between the monthly average of global solar radiation (Rs), N0, and Ne(lux) were investigated. At low light intensity (<500 lx), Ne(lux) were almost the same as N0. At high light intensity (>10,000 lx), Ne(lux) and Rs showed a logarithmic relationship. Using these relationships, empirical models were derived to estimate the effective day length at different light intensities. According to the validation of the model, the effective day length for any light intensity could be estimated with an accuracy of less than 11% of the mean absolute percentage error (MAPE) in the estimation of the monthly base photoperiod. Recently, a number of studies have provided support for a link between day length and some diseases. Our results will be useful in further assessing the relationships between day length and these diseases