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Corneal localization of the ulcers was distributed as in 96(61.5%) patients central and in 60 (38.5%) peripheral. The diameter of the corneal ulceration was of 12mm in 24(15.4%), 3 4mm in 78(50.0%), 5 6mm in 24(15.4%), 7 8mm in 26(16.7%) patients, 4 (2.6%) patients had entire corneal involvement. Ulceration depth was less than 1/3 conreal thickness in 82(52.6%), between 1/3 to 2/3 in 60(38.5%) patients and over 2/3 in 14(9.0%) patients (Table 3).
Anterior chamber inflammation was absent in 42 (26.9%) patients. A 1+ to 2+ Tyndall effect with 1+ to 2+ cells was present in 64 (41%) patients, and severe anterior chamber inflammation (3+ to 4+ Tyndall effect and cells, with or without hypopyon) was present in 50 (32.1%) patients (Table 3). In 125 (80%) patients, bacteria were isolated from the corneal smears (Table 4). Sixtynine percent of isolated bacteria were Gram positive, most of them 75(60%) were staphylococcus aureus. Gram negative bacteria were isolated in 39(31%) patients. Most of them were pseudomonas and yersina. Infection with Gram negative organisms associated with severe anterior chamber inflammation (P=0.003) and depth more than 2/3 of cornea (P=0.001). All isolated bacteria were tested on currently used 10 antibiotics.
One hundred and fourteen (73.1%) patients were treated according to the standard protocol by using fortified antibiotic drops for Gram positive and Gram negative organisms. The remaining 42 (26.9%) patients who did not stay at hospital and had small infiltration were, treated by commercially available antibiotic fluoroquinolone (Moxifloxacin).
Table 1Demographic data of 156 patients with bacterial corneal ulcern（略）
Table 2Frequency of risk factors in bacterial corneal ulcern（略）
Table 3Clinical features of corneal ulcer（略）
Table 4Organisms isolated in bacterial corneal ulcers（略）
Figure 1Pre and post treatment visual status of patients（略）
Clinical Outcome Visual acuity on presentation ranged from 6/6 to no light perception. Mean visual acuity was 2.67 (SD 1.01). Forty percent of patients had good visual outcome with visual acuity same or better than the level at admission (Figure 1). Among the others 60% patients final outcome was poor. Complications of bacterial corneal ulcer were noted in 45 (28.8%) patients. Among them, glaucoma in 11 patients, endophthalmitis in 3 patients, anterior staphyloma in 3 patients and corneal perforation, descmetocele, cataract each develops in 3 (4.5%) patients. Where as one hundred and eleven (71.2%) patients had no severe complications, except scaring at the site of lesion. In our study statistical analysis revealed that poor visual outcome was correlated with history of ocular surface disease (P<0.01), large size and central localizations of the ulcer (P<0.01), and depth of infiltrate more than 1/3 corneal thickness (P<0.01).
DISCUSSION
Corneal infection is the leading cause of ocular morbidity and blindness worldwide. In the published reports, bacterial corneal ulcer has been found to be 13.0% to 29.3% of all cases of ulcerative corneal ulcer[6].
Of the remaining 240 patients with infective keratitis from April 2006 to March 2008 presenting at our department, bacterial corneal ulcer was diagnosed in 156 (65.0%) eyes. Although it is rare in the absence of a predisposing factor. Most of the cases of microbial keratitis were associated with ocular trauma. In this study 86 (55.0%) were associated with various types of ocular injuries. Vegetative trauma accounts 46 (29.5%) patients. Vajpayee et al reported 77.5% of cases of bacterial corneal ulcer occurred by trauma in low income countries, where a large number of population were concerned to agriculture. Moreover, the climate is mild and humid, and malnutrition is common[7] . Foreign body induced corneal ulcer was the second most common (24 cases,15.38%) predisposing factor in our study. Most of these patients had also history of foreign body removal by own or by other family members and followed by selfmedications.
Ocular surface disorders such as dry eye syndrome and eye lid pathologies and keratopathies accounted 17.3% of cases. Bourcier et al[2] reported 21% of cases of bacterial corneal ulcer were with ocular surface disorder. Contact lenses remained the least common cause of bacterial corneal ulcer in our study. In contrast Radford et al reported contact lenses had greatly increased the risk of bacterial keratitis which was estimated to be 1015 times higher with the use of extended wear disposable contact lenses. Many physiopathological effects of contact lenses wear have been reported. The most important of which is an induced hypoxia and hypercapinia of the cornea. In line with other studies[8,9] males (65.4%) were predominant in our study. The increased risk in males in our population was probably due to their more active involvement in out door activities, which subsequently increased their vulnerability to this blinding disease. The duration from the onset of symptoms to the presentation at our department ranged from 7 to 105 (mean 41） days. This delay presentation to tertiary center might be due to the fact that the patient already received the therapy from their nearest ophthalmologists or doctor and were referred when the ulcers did not respond. Xie et al[7] reported the first visit of 41.0% between 16 and 30 days.
In this study, the most common signs on slit lamp examination were epithelial defect, stromal infiltrate and suppuration presents in every case, while anterior chamber reaction and hypopyon was observed in 73% of patients. This is in accordance with another European study[2]. Older individuals were more frequently affected in this study, majority (61%) of patients were fifth or more decades. Age profile in our patients is comparable to Schaefer et al and Cohen et al study. In general older age, delay in referral, topical steroid treatment, past ocular surgery, poor vision at presentation, large size of ulcer[10], and central and deep ulcer are all major risk factors for evisceration and enucleation in patients with bacterial corneal ulcer. The situation in this study was not too different.
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