Discussion
RP is a common hereditary eye disease and most RP patients are complicated with cataract. The lens opacification often occurs in the central of posterior capsule or posterior polar cortex(3), which seriously affects the residual tubular vision. For patients with RP complicated with cataract, current studies have proved that most patients have improved visual acuity and visual field after surgery(4), and the effect is clear. Cataract surgery itself is safe and reliable, and does not lead to the occurrence and progress of other RP related complications. Therefore, it is suggested that RP complicated with cataract should be treated by surgery(5-7). The results of this study also showed that vision was improved in most patients, the operation effect was good, and the operation was safe and reliable.
Most studies have reported that the final postoperative vision of patients is closely related to the structure of macular area(8, 9). In this study, it was also found that the visual acuity of patients with relatively healthy macular before surgery was significantly improved, while the improvement in visual acuity of patients with significantly thinner macular was limited. This also suggests that for RP patients with cataract, preoperative OCT examination is very important for the prediction of postoperative vision(10).
Due to the common lens suspensory ligament relaxation in RP patients with cataract, it is necessary to pay attention to the prevention and treatment of capsule tear, suspensory ligament rupture and other related intraoperative complications. The capsule contraction of such patients is relatively rapid after surgery. The suspensory ligament relaxation tends to cause CCS and dislocation of the IOL(11). In this study, four cases of CCS occurred in patients without CTR implantation, and were treated with capsule loosening operation at six months after the cataract surgery. There was no CCS among CTR implanted patients. Bayyoud T, etc(12). reported that there were 52 eyes of RP with cataract surgery patients. Two cases of CCS happened in no implanted CTR group, while there no CCS occurred in implanted CTR group after a median follow-up of 26 months, and the incidence was 4%. It also suggested that CTR implantation can help to reduce the postoperative CCS in RP with cataract surgery. In addition, patients with RP complicated with cataract are relatively young in age, and posterior capsular opacity (PCO) occurs quickly, which requires timely treatment. CTR implantation also has certain effects on the prevention of PCO(12).
The results of this study showed that IOP was higher and corneal ECC was less after surgery. Though they were in normal range, it indicated that attention should be paied to the IOP and ECC in RP with cataract surgery. There were some reports on the occurrence of the postoperative macular edema in RP with cataract surgery(5, 12). However, it was not found in the current study. The occurrence of postoperative macular edema of cataract surgery associated with many factors. The visual acuity of RP patients was poor due to the severe retinopathy before surgery, and macular edema after surgery would further compromise the vision. Hence, it is crucial to carry out postoperative OCT examination regularly.