Quantitative analysis of vector dose-dependent transgene expression. Mouse eyes were injected with 1 μL of a CMV LacZ vector at increasing concentrations of 1 × 107 vp/μL, 1 × 108 vp/μL and 1 × 109 vp/μL. Eyes were enucleated, processed for X-gal staining and measured for β-galactosidase activity levels. Transgene expression was determined by luminescence and reported as a fold increase relative to the control. Statistical analysis revealed no significant difference between the time points. However, activity levels were determined to be significantly different with the increase in viral vector dose suggesting that a dose-dependent relationship exists (2-way ANOVA; dose p < 0.05; time p > 0.05; interaction p>0.05). Error bars indicate standard error of the mean (SEM) and 4 mice were used for each time point of each vector dose.