**7. Endophthalmitis post-penetrating keratoplasty**

Endophthalmitis following penetrating keratoplasty (PK) occurs at a slightly higher rate compared to other intraocular procedures. The incidence ranges from 0.2% to 0.4% [43, 44].

Risk factors include; large circumferential incision, wound dehiscence, suture abscess, and contaminated donor tissue [44]. In addition, chronic use of topical steroids which are known to decrease immune defense may increase the risk of endophthalmitis.

Symptoms are similar to other types of postoperative endophthalmitis. The causative agents are predominantly gram-positive bacteria (Streptococcus and Staphylococcus). On the other hand, gram-negative bacteria account for nearly 20% of cases.

The outcomes can be devastating with severe visual loss in 50% of cases and often a requirement of repeat keratoplasty [45].

Overall, the frequency of endophthalmitis in modern corneal transplant surgery is expected to decrease significantly with the advancement in lamellar keratoplasty. In a study conducted by Heinzelmann et al., it was apparent that the outcome of lamellar endothelial keratoplasty and Descemet membrane endothelial keratoplasty is superior to PK without serious complications, such as exogenous endophthalmitis [46].
