Corneal endothelial cell .loss after manual small incision cataract surgery and phacoemulsification at Muhimbili National Hospital, Dar es salaam.

Abstract

Background: Cataract is the world’s leading cause of blindness with around 20 million people bilaterally blind due to cataract1. The definitive treatment of cataract is surgical removal of the opacified lens which is aimed at restoring normal vision 3, 5. However, every cataract extraction even in experienced hands is associated with some endothelial cell damage. Endothelial cell loss if sufficiently severe can cause endothelial cell density to fall below the threshold level needed to maintain corneal transparency. This can lead to the development of late corneal decompensation which ultimately leads to poor visual outcome which has been reported to occur in about 1% of cataract extractions 7, 11, 27, 28, 29. Broad objective: To assess the corneal endothelial cell loss after manual small incision cataract surgery and phacoemulsification at Muhimbili National Hospital, Dar es Salaam. Methodology: A hospital based descriptive, prospective cohort study was conducted between April 2012 and January 2013. A total of 127adult patients with 131eyes who underwent cataract surgery at MNH were enrolled. Patients were examined whereby demographic data, pre and post operative corneal endothelial cell count as well as post operative visual acuity were recorded. Corneal endothelial cell count was determined by use of a TOPCON SP.2000P specular microscope. Results: All 131 eyes assessed by specular microscope had preoperative corneal endothelial cell count ranging from 1500 – 3000 cells/mm2 which decreased with increasing age (P<0.01). Eighty nine eyes (67.9%) underwent MSICS while 42 eyes (32.1%) underwent phacoemulsification with 84 eyes (64.1%) been for males and 47 eyes (35.9%) for females. Fifty four (60.7%) out of 89 eyes lost significant cornea endothelial cells on day 1 with average cell loss of 611.1 cells/mm2 while 33 eyes (37.1%) had a significant cell loss 1 month post MSICS. In the phacoemulsification group, 19 (45.2%) out of 42 eyes had a significant cornea endothelial cell loss on day 1 with an average endothelial cell loss of 552.6 cells/mm2 while 12 eyes (28.6%) lost cells 1 month post phacoemulsification. An accelerated decrease in corneal endothelial cell count in MSICS and phaco groups one month post cataract surgery 7 was also noted in 17 eyes (19.1%) in MSICS group and 3 eyes (7.14%) in phaco group. However, there was no statistically significant association between postoperative visual acuity and different levels of corneal endothelial count on first day and one month post cataract surgery with P values of 0.111 and 0.142 on first day, 0.716 and 0.213 after one month for MSICS and phacoemulsification respectively. Conclusion: The loss of cornea endothelial cells post cataract surgery at MNH is significant although not to an extent of causing cornea oedema. Recommendations 1. Emphasis on preoperative corneal endothelial cell evaluation should be done. 2. Further study is proposed to identify the factors responsible for corneal endothelial cell loss as well as long term follow up of post cataract surgery patients.