ObjectiveTo observe aqueous cytomegalovirus (CMV) DNA load in patients with cytomegalovirus retinitis (CMVR) after allogeneic hematopoietic stem cell transplantation (Allo-HSCT), and to explore influencing factors for transient elevation of CMV-DNA load during the treatment. MethodsA retrospective study. From January 2016 to July 2020, 28 eyes of 19 patients with CMVR after Allo-HSCT diagnosed in the Department of Ophthalmology of Peking University People's Hospital were included in the study. Among them, there were 8 males with 12 eyes, 11 females with 16 eyes; the mean age was 28 years; 10 patients were unilateral and 9 patients were bilateral. During the course of treatment and follow-up, the blood CMV-DNA remained negative. All patients were treated with intravitreal injection of 60 mg/ml ganciclovir 0.05 ml (containing ganciclovir 3 mg), twice a week for two weeks in induction phase and weekly injection in maintenance phase. Aqueous humor sample was collected during injection of ganciclovir (IVG) and CMV-DNA load was determined by real-time quantitative polymerase chain reaction. Intravitreal treatment was terminated if aqueous CMV-DNA load turned negative after the fourth or later intravitreal injection. The patients were followed up every 2 weeks for at least 6 months. Serum CMV-DNA was negative in all patients during treatment and follow-up. All the eyes were divided into continuous decline group and non-continuous decline group depending on whether there was transient elevation of aqueous CMV-DNA load, and data between two groups were compared. Pearson linear regression analysis was used to analyze the correlation between aqueous CMV-DNA load and injection times or treatment duration. ResultsAt the end of treatment, the median number of IVG in the affected eye was 7 (4, 9). The results of correlation analysis showed that the aqueous humor CMV-DNA load of the affected eye was related to the number of treatments [R2=0.385, P＜0.000 1, B=－0.237 log10 copies/(ml · time)], and the duration of treatment [R2=0.394, P <0.000 1, B=－0.301 log10 copies/(ml · week)] were negatively correlated. Among the 28 eyes, 13 eyes (46.4%, 13/28) in the continuous decline group and 15 eyes (53.6%, 15/28) in the non-sustained decline group. Baseline visual acuity (t=－1.223), intraocular pressure (t=1.538), aqueous humor CMV-DNA load (t=－0.109), retinitis lesion area (Z=－0.308) in the continuous decline group and the non-continuous decline group), the number of quadrants involved (Z=－0.024) and whether the macula was involved (Z=－1.826), combined with anterior segment inflammation (Z =－0.499), combined with high intraocular pressure (Z=－1.342), terminal visual acuity (t =－0.845), intraocular pressure (t=－0.068), total IVG times (Z=0.907), age (Z=－0.832), gender composition (Z=－1.074), etc. The difference was not statistically significant (P＞0.05). ConclusionThe CMV-DNA load in aqueous humor decreases by about 50% every week during the treatment of CMVR eyes after Allo-HSCT; the transient increase in the CMV-DNA load in the aqueous humor during treatment does not affect the treatment process and clinical prognosis.