**6. Endophthalmitis following cataract surgery**

Over 90% of post-operative endophthalmitis develop as a complication of cataract surgery since it is the most common intraocular surgery performed by ophthalmologists worldwide (Figure 6). [3, 40] A century ago, the incidence of endophthalmitis after cataract operations was over 10% which has dramatically decreased since the advent of antibiotics and the uti‐ lization of aseptic techniques. During the era of extra capsular cataract extraction under im‐ proved hygiene conditions, the infection rate has fallen below 0.1% in the developed countries. [2] In the absence of prospective randomized case-controlled studies, the true inci‐ dence of endophthalmitis may be difficult to determine given its rare occurrence within a single center. [1-3] Recently, clinical features, microbiology and final visual outcome as well as the incidence of acute-onset post-operative endophthalmitis after cataract surgery have been reported from Saudi Arabia by Al-Mezaine et al, [12] from a single tertiary eye care center over a 10-year period. According to their retrospective series, the incidence of acuteonset endophthalmitis after cataract surgery was 0.068% and the most common presenting features were pain and poor red reflex. Staphylococcus species and Streptococcus species were the most common micro-organisms encountered. Visual outcomes were good in cases of endophthalmitis following phacoemulsification and in those caused by Staphylococcus epidermidis and worse in cases that were caused by Streptococcus species. Overall, clear corneal phacoemulsification had a 1.73-fold higher risk for acute endophthalmitis than ex‐ tra-capsular cataract extraction but the visual outcome was worse in post-extra capsular cat‐ aract extraction cases. In this series, the poor visual outcome was associated with more virulent organisms and delayed presentation. [12]

**Figure 6.** External photograph of a 65-years-old female who underwent uneventful cataract extraction along-with in‐ traocular lens implantation in her left eye. Two weeks later, she presented with painful left eye and complete loss of vision (a). She was found to have necrosis of her left corneal wound and extrusion of the implanted intra-ocular lens (b).

A review of the literature has provided a greater number of patients with risk factors for the development of endophthlamitis. [2, 3, 40] In a systematic review of the literature by Taban et al, [41] of 215 studies of 3,140,650 cataract extractions published between 1963 and 2003, a higher overall post-cataract endophthalmitis rate occurred between 2000 and 2003 (0.265%) as compared with between 1963 and 2000 (0.128%). The rate of endophthalmitis was higher with clear cornea incision (0.189%) versus scleral incision (0.079%) between 1992 and 2003. In another large population-based review of United States Medicare beneficiary claims be‐ tween 1994 and 2001 of 447,627 cataract operations, 1026 cases of presumed endophthalmitis were noted and an increased incidence was associated with the introduction of clear cornea incision. [42] The incidence of endophthalmitis was higher from 1998 to 2001 (2.5 per 1000) as compared with between 1994 and 1997 (1.8 per 1000), possibly reflecting the increasing use of clear corneal incisions during this time period. Some limitations to these larger stud‐ ies are their being retrospective in nature that may differ in methodology and definitions. In addition, decreased preoperative use of povidine-iodine and fewer administrations of subconjunctival injections at the end of surgery may have occurred as ophthalmologists con‐ verted from retro-bulbar or peri-bulbar anesthesia to topical anesthesia during this time period which may be confounding factors leading to an increased rate of endophthalmitis. [2, 3, 42]

Following intraocular surgery, leak-proof closure of the corneal incision is recommended to limit access of microorganisms to the anterior chamber. [43] Evidence indicates that with the clear corneal incision, in the absence of sutures, the wound appears to be loose allowing mi‐ croorganisms to enter into the eye and subsequent development of endophthalmitis. Type of wound closure may also be an important determinant of the endophthalmitis following PPV. [3, 44] As compared to the cataract surgery, the incidence of endophthalmitis following PPV is low and ranges between 0.03-0.05%. [3] However, even after PPV, the use of sutureless and minimal incision techniques have been found to be associated with higher inci‐ dence of post-operative endophthalmitis than standard closure technique.
