With modern cataract surgical techniques, the incidence of post-surgical cystoid macular edema (CME) has decreased to 0.1–2.35 % [9]. Several mechanisms may contribute to such macular edema, including the effects of vitreoretinal traction, light damage, production of prostaglandins and intraoperative complications [1, 10]. The rate of macular edema after cataract surgery is increased in the presence of diabetic retinopathy and uveitis [11, 12]. However, the two cases were notable for its unremarkable retinopathy and lack of history of diabetes or uveitis.
Jurecka et al. [13] found a positive statistical correlation between the real phacoemulsification time and the increase in macular retinal thickness after surgery. In the present cases, the real phacoemulsification time was not long, and the average power was low.
Cefuroxime toxicity may be one of the cause of macular edema and detachment. The recommended dose of intra-cameral cefuroxime injection is 0.1 ml of 10.0 mg/ml solution. The fact that excessive cefuroxime solution injections into the anterior chamber can cause early serous macular detachment and edema has been reported previously [3, 4]. The reported dose has been varied from 20 to 50 mg/ml. However, recently, Kontos et al. [14] reported a case with acute serous macular detachment and macular edema after a standard dose of subconjunctival cefuroxime injection in the phacoemulsification. Faure et al. [15] even reported a case occurred retinal toxicity the second day after surgery with a standard dose of intra-cameral cefuroxime injection in France. In the present two cases in China, early macular edema and extensive retinal detachment were found immediately the first day after surgery with a standard dose of intra-cameral cefuroxime injection at the end of the phacoemulsification. The visual loss was earlier in the present two cases than that of Faure et al. report. Though the visual loss time after surgery had little difference, the manifestations of these cases were similar. The interval time between the present two cases was about one month. No abnormality was found during the drug dilution process. Thus, we presume that the retina injury in the two cases may be also attributed to cefuroxime toxicity even under a use of a standard dose.
In these two cases, the location of the edema was unusual: Typically retinal edema was located in the outer plexiform layer. However, in these cases the outer plexiform layer appeared to be spared and the outer nuclear layer had large edema. There was extensive subretinal fluid without debris. These OCT characteristics were similar to the manifestation that has been identified in OCT of the retinal toxicity caused by excessive cefuroxime solution injections [3, 4], and might provide a marker for cefuroxime toxicity. The mechanism of this pattern of edema is unclear. The electroretinogram (ERG) results of animal experiments [16] and human clinical observation [15] prompted cefuroxime was toxic to retina, and may effect the Müller cell function. Previous study [3, 4] reported that fluorescein angiograms (FA) showed diffuse leakage without abnormal retinal perfusion in cefuroxime toxic eyes and indicated that the blood–retinal barrier at the retinal pigment epithelium (RPE) may be disrupted. It is a limitation that the FA was not obtained in the present two cases, but the SD-OCT images may suggest that the primary lesions were localized at the outer retinal and RPE.
Clear vitreous haze has been reported in ocular toxicity after intra-cameral injection of very high doses of cefuroxime during cataract surgery [4]. But, no sign of remarkable inflammation in the vitreous was found in the present cases. No abnormality in vitreous has also been reported by Buyukyildiz in two cases of retinal toxicity caused by 2 mg/0.1 ml cefuroxime intra-cameral injection [3]. The dose of cefuroxime injection was much higher in Delyfer et al. study [4] than the presented cases and Buyukyildiz et al. cases [3]. The different doses of cefuroxime injection during cataract surgery may lead to the different findings in vitreous.
Topical nonsteroidal anti-inflammatory drugs and corticosteroids have been reported to be effective and safe therapy for preventing post-surgical ocular inflammatory and macular edema [17–20]. Thus combination of nonsteroidal anti-inflammatory drugs and corticosteroids was applied in the present cases topically as routine anti-inflammation treatment after phacoemulsification. The SD-OCT image revealed a quick recovery from the macular edema without any special surgical intervention 1 week later. Delyfer et al. [4] also reported that retinal injury and visual dysfunction induced by intra-cameral excessive cefuroxime injection were able to recover to normal without surgery intervention after 6 weeks. The recovery time was shorter in the present cases than previous report. That may be due to the much lower concentration of cefuroxime solution used in the two cases. These results suggest that early macular edema with extensive serous retinal detachment which may be attributed to cefuroxime toxicity are restorable. Routine anti-inflammatory treatment is sufficient and do not require excessive interventions.