Microbial Keratitis in South India: Influence of Risk Factors,Climate, and Geographical Variation

Purpose: To determine the influence of risk factors, climate, and geographical variation on the microbial keratitis in South India. Methods: A retrospective analysis of all clinically diagnosed infective keratitis presenting between September 1999 and August 2002 was performed. A standardised form was filled out for each patient, documenting sociodemographic features and information pertaining to risk factors. Corneal scrapes were collected and subjected to culture and microscopy. Results: A total of 3,183 consecutive patients with infective keratitis were evaluated, of which 1,043 (32.77%) were found to be of bacterial aetiology, 1,095 (34.4%) were fungal, 33 (1.04%) were Acanthamoeba, 76 (2.39%) were both fungal and bacterial, and the remaining 936 (29.41%) were found to be culture negative. The predominant bacterial and fungal pathogens isolated were Streptococcus pneumoniae (35.95%) and Fusarium spp. (41.92%), respectively. Most of the patients (66.84%) with fungal keratitis were between 21 and 50 years old, and 60.21% of the patients with bacterial keratitis were older than 50 (p < 0.0001) (95% CI: 5.19–7.19). A majority of patients (64.75%) with fungal keratitis were agricultural workers (p < 0.0001) [odds ratio (OR): 1.4; 95% CI: 1.19–1.61], whereas bacterial keratitis occurred more commonly (57.62%) in nonagricultural workers (p < 0.0001) (OR: 2.88; 95% CI: 2.47–3.36). Corneal injury was identified in 2,256 (70.88%) patients, and it accounted for 92.15% in fungal keratitis (p < 0.0001) (OR: 7.7; 95% CI: 6.12–9.85) and 100% in Acanthamoeba keratitis. Injuries due to vegetative matter (61.28%) were identified as a significant cause for fungal keratitis (p < 0.0001) (OR: 23.6; 95% CI: 19.07–29.3) and due to mud (84.85%) for Acanthamoeba keratitis (p < 0.0001) (OR: 26.01; 95% CI: 3.3–6.7). Coexisting ocular diseases predisposing to bacterial keratitis accounted for 68.17% (p < 0.0001) (OR: 33.99; 95% CI: 27.37–42.21). The incidence of fungal keratitis was higher between June and September, and bacterial keratitis was less during this period. Conclusion: The risk of agricultural predominance and vegetative corneal injury in fungal keratitis and associated ocular diseases in bacterial keratitis increase susceptibility to corneal infection. A hot, windy climate makes fungal keratitis more frequent in tropical zones, whereas bacterial keratitis is independent of seasonal variation and frequent in temperate zones. Microbial pathogens show geographical variation in their prevalence. Thus, the spectrum of microbial keratitis varies with geographical location influenced by the local climate and occupational risk factors.     

Medical treatment for combined Fusarium and Acanthamoeba keratitis

Purpose: Acanthamoeba and fungal keratitis are rare ocular infections. We report cases of combined Fusarium and Acanthamoeba keratitis and the clinical course of medical treatment. Methods: We reviewed the medical records of patients treated for culture‐proven Acanthamoeba keratitis at a referral centre, during 2001?2006. Results: Eleven consecutive patients were treated for culture‐proven Acanthamoeba keratitis during the 5 years, two of whom had combined fungal infections. A 29‐year‐old man presented with ground‐glass corneal oedema and epitheliopathy caused by contact lens use. The other patient, a 7‐year‐old girl, had eye trauma that led to a feathery corneal infiltrate. Both cases were treated with topical 0.02% polyhexamethylene biguanide (PHMB), 0.1% propamidine, 1% clotrimazole and 5% natamycin. Therapeutic keratoplasty was not required in either case. Conclusions: Timely identification of the pathogen, with repeated culture and smear if necessary, as well as adequate dosage to prevent recurrence is highly recommended in order to preclude the need for therapeutic penetrating keratoplasty.     

Review of epidemiological features, microbiological diagnosis and treatment outcome of microbial keratitis: Experience of over a decade

Purpose:

To review the epidemiological characteristics, microbiological profile, and treatment outcome of patients with suspected microbial keratitis.

Materials and Methods:

Retrospective analysis of a non-comparative series from the database was done. All the patients presenting with corneal stromal infiltrate underwent standard microbiologic evaluation of their corneal scrapings, and smear and culture-guided antimicrobial therapy.

Results:

Out of 5897 suspected cases of microbial keratitis 3563 (60.4%) were culture-proven (bacterial – 1849, 51.9%; fungal – 1360, 38.2%; Acanthamoeba – 86, 2.4%; mixed – 268, 7.5%). Patients with agriculture-based activities were at 1.33 times (CI 1.16–1.51) greater risk of developing microbial keratitis and patients with ocular trauma were 5.33 times (CI 6.41–6.44) more likely to develop microbial keratitis. Potassium hydroxide with calcofluor white was most sensitive for detecting fungi (90.6%) and Acanthamoeba (84.0%) in corneal scrapings, however, Gram stain had a low sensitivity of 56.6% in detection of bacteria. Majority of the bacterial infections were caused by Staphylococcus epidermidis (42.3%) and Fusarium species (36.6%) was the leading cause of fungal infections. A significantly larger number of patients (691/1360, 50.8%) with fungal keratitis required surgical intervention compared to bacterial (799/1849, 43.2%) and Acanthamoeba (15/86, 17.4%) keratitis. Corneal healed scar was achieved in 75.5%, 64.8%, and 90.0% of patients with bacterial, fungal, and Acanthamoeba keratitis respectively.

Conclusions:

While diagnostic and treatment modalities are well in place the final outcome is suboptimal in fungal keratitis. With more effective treatment available for bacterial and Acanthamoeba keratitis, the treatment of fungal keratitis is truly a challenge.     

Acridine Orange Staining for Rapid Diagnosis of Acanthamoeba Keratitis

Acanthamoeba keratitis is uncommon, but one of the most severe infectious diseases of the cornea. Delayed diagnosis or misdiagnosis as bacterial or herpes simplex keratitis leads to extensive corneal inflammation and profound visual loss. Therefore, accurate and rapid diagnosis of Acanthamoeba keratitis is essential for successful treatment and good prognosis. We evaluated the usefulness of acridine orange staining from corneal scrapings and contact lens solutions for the rapid diagnosis of four consecutive cases of Acanthamoeba keratitis. Gram stain and culture on nonnutrient agar plates with Escherichia coli overlay were also made. Corneal scrapings stained with acridine orange revealed yellow-to-orange polygonal, cystic structures consistent with the appearance of Acanthamoeba among inflammatory cells and the corneal epithelial cells. The contact lens case solutions of two patients also showed numerous cysts with double wall. Some organisms from the third patient were identified as Acanthamoeba castellani and others as Acanthamoeba lugdunensis. Based on the acridine orange staining results in four cases of Acanthamoeba keratitis, this stain is recommended as a simple and reliable method for the rapid diagnosis of this disease.     

Bacteria commonly isolated from keratitis specimens retain antibiotic susceptibility to fluoroquinolones and gentamicin plus cephalothin

PURPOSE: Patients presenting with presumed infective keratitis were studied to determine predisposing factors, the current susceptibilities of the bacterial isolates to a range of relevant antibiotics, the success rate of topical antibiotic treatment of keratitis and predictors of failure of topical therapy. METHODS: Corneal scrapings taken from patients who presented between January 2002 and December 2003 to the Sydney Eye Hospital Emergency Department with keratitis were cultured. The minimum inhibitory concentration of selected antibiotics was determined for each bacterial isolate using an agar dilution technique. RESULTS: One hundred and twelve consecutive patients presented with corneal ulcers. Forty-seven of the 112 (42%) patients had a growth from the corneal scraping. Potential predisposing factors were identified in 64% of patients, most frequently contact lens wear (36% of patients). Coagulase-negative staphylococci were the most common species isolated. Other common organisms isolated include Pseudomonas aeruginosa, Corynebacterium spp., Staphylococcus aureus and Streptococcus spp. CONCLUSIONS: Most microorganisms isolated from patients with bacterial keratitis showed susceptibility to ciprofloxacin and aminoglycosides. Cephalothin plus aminoglycoside constituted an effective initial broad-spectrum antibiotic combination. The success rate of topical antibiotic treatment of corneal abscess is 89%. Predictors of failure include older age group, medium or large ulcer, culture-negative keratitis, hypopyon and poor visual acuity.     

Microbial keratitis following corneal transplantation

PURPOSE: To determine the predisposing risk factors and analyse the clinical and microbiological profiles of microbial keratitis following corneal transplantation. METHODS: A retrospective analysis was done of hospital records of all patients who presented with microbial keratitis in the corneal graft between July 2000 and June 2005 at the Corneal Unit of Royal Victorian Eye and Ear Hospital, Melbourne, Australia. RESULTS: Eighty-one episodes of infection were identified in 62 patients over a 5-year period. Thirteen patients had multiple episodes of infection. The mean age of the patients was 70 +/- 16 years (range: 22-92 years). The median time interval between the graft and infection was 17 months (range: 6 days to 385 months). Twenty-two (35%) episodes of primary infection were related to sutures. The associated predisposing risk factors were failed graft (40%), dry eye (18%), Herpes simplex keratitis (8%), and ocular surface disease (8%). Forty-seven (76%) cases were culture positive for bacteria. Ten cases were positive for Herpes simplex virus (HSV) during presentation. CONCLUSION: Failed graft is a long-term risk factor for graft infection in addition to ocular surface disease and H. simplex keratitis. All the predisposing risk factors increase the risk of recurrent graft infection.     

Infectious keratitis: an update on epidemiology,causative microorganisms,risk factors,and antimicrobial resistance

Corneal opacity is the 5th leading cause of blindness and visual impairment globally, affecting ~6 million of the world population. In addition, it is responsible for 1.5–2.0 million new cases of monocular blindness per year, highlighting an ongoing uncurbed burden on human health. Among all aetiologies such as infection, trauma, inflammation, degeneration and nutritional deficiency, infectious keratitis (IK) represents the leading cause of corneal blindness in both developed and developing countries, with an estimated incidence ranging from 2.5 to 799 per 100,000 population-year. IK can be caused by a wide range of microorganisms, including bacteria, fungi, virus, parasites and polymicrobial infection. Subject to the geographical and temporal variations, bacteria and fungi have been shown to be the most common causative microorganisms for corneal infection. Although viral and Acanthamoeba keratitis are less common, they represent important causes for corneal blindness in the developed countries. Contact lens wear, trauma, ocular surface diseases, lid diseases, and post-ocular surgery have been shown to be the major risk factors for IK. Broad-spectrum topical antimicrobial treatment is the current mainstay of treatment for IK, though its effectiveness is being challenged by the emergence of antimicrobial resistance, including multidrug resistance, in some parts of the world. In this review, we aim to provide an updated review on IK, encompassing the epidemiology, causative microorganisms, major risk factors and the impact of antimicrobial resistance.Subject terms: Corneal diseases, Epidemiology, Risk factors     

Acanthamoeba keratitis and contact lens wear

Acanthamoeba keratitis is a rare but serious complication of contact lens wear that may cause severe visual loss. The clinical picture is usually characterised by severe pain, sometimes disproportionate to the signs, with an early superficial keratitis that is often misdiagnosed as herpes simplex virus (HSV) keratitis. Advanced stages of the infection are usually characterised by central corneal epithelial loss and marked stromal opacification with subsequent loss of vision. In this paper, six cases of contact lens‐related Acanthamoeba keratitis that occurred in Australia and New Zealand over a three‐year period are described. Three of the patients were disposable soft lens wearers, two were hybrid lens wearers and one was a rigid gas permeable lens wearer. For all six cases, the risk factors for Acanthamoeba keratitis were contact lens wear with inappropriate or ineffective lens maintenance and exposure of the contact lenses to tap or other sources of water. All six patients responded well to medical therapy that involved topical use of appropriate therapeutic agents, most commonly polyhexamethylene biguanide and propamidine isethionate, although two of the patients also subsequently underwent deep lamellar keratoplasty due to residual corneal surface irregularity and stromal scarring. Despite the significant advances that have been made in the medical therapy of Acanthamoeba keratitis over the past 10 years, prevention remains the best treatment and patients who wear contact lenses must be thoroughly educated about the proper use and care of the lenses. In particular, exposure of the contact lenses to tap water or other sources of water should be avoided.     

Restriction enzyme analysis of mitochondrial DNA of Acanthamoeba strains isolated from corneal lesions

Although Acanthamoeba keratitis has been recognized as one of the important infectious diseases of the cornea, especially in contact lens wearers in recent years, its taxonomy has not been well established. We carried out mitochondrial DNA (mtDNA) analysis of the Acanthamoeba organisms isolated from corneal lesions in four eyes of three patients who had suffered from keratitis. The mtDNA was analyzed by restriction fragment length polymorphism (RFLP) using restriction enzymes BglII and EcoRI. The RFLP analyses revealed that the DNA phenotypes of the Acanthamoeba organisms were identical to those of the Ma strain in two patients and to the Castellani strain in one patient.     

Risk factors for perforation in microbial corneal ulcers in north India

AIM: To identify predisposing factors leading to corneal perforation in patients with microbial keratitis. METHOD: Two groups of 60 patients each, with perforated corneal ulcers and healed/healing corneal ulcers, respectively, were recruited in a case-control study conducted in northern India. The cases and controls were matched by age and time of presentation. A standardised proforma was used to identify potential predisposing factors for demographic, social, medical, ocular, and treatment history. All participants underwent a detailed ocular examination. Corneal scrapings were performed where relevant. RESULTS: The characteristics associated with corneal perforation in microbial keratitis were outdoor occupation (p = 0.005), illiteracy (p = 0.02), excessive alcohol use (p = 0.03), history of "something falling into eye" (p = 0.003), trauma with vegetable matter (p = 0.008), vision less than counting fingers at referral (p<0.001), central location of ulcer (p<0.001), lack of corneal vascularisation (p<0.001), delay in starting initial treatment (p<0.001), failure to start fortified antibiotics (p<0.001), and monotherapy with fluoroquinolones (p = 0.002). The lack of corneal vascularisation (OR 6.4, 95% CI 4.2 to 13.5), delay in starting initial treatment (OR 35.6, 95% CI 6.9 to 68.2), and failure to start fortified antibiotics (OR 19.9, 95% CI 2.7 to 64.7) retained significance on a logistic regression model. CONCLUSIONS: This study characterises microbial keratitis cases at increased risk of corneal perforation and reinforces the need for standardised referral and treatment protocols for patients with corneal ulcer on their first contact at primary care level in the developing world.     

Infectious Keratitis Following Corneal Crosslinking: A Systematic Review of Reported Cases: Management,Visual Outcome,and Treatment Proposed

Aim: To describe the infectious complications and the group of pathogens involved in the infection following corneal crosslinking, the visual outcome, and the treatment proposed. Methods: A Medline (National Library of Medicine, Bethesda, MD, USA) search from October 2000 to October 2013 was performed to identify all articles describing infectious keratitis following corneal crosslinking treatment. Nineteen articles were selected. Ten articles reported infectious complications of corneal crosslinking treatment were included. Nine articles were excluded, because seven described sterile keratitis, one article was in German, and one reported general complication without describing the infection complication. Results: A total number of infections reported included 10 eyes. The infectious keratitis was associated with bacteria in five eyes (50%): gram-positive bacteria in three eyes (30%) (staphylococcus epidermidis, S. aureus and streptococcus salivarius plus S. oralis, respectively) and gram-negative bacteria in two eyes (20%) (E. coli; P. aeruginosa); there was herpes virus in two eyes, fungus in two eyes (Fusarium and Microsporidia) (20%), and Acanthamoeba in one eye (10%). Conclusions: Only 10 cases of infectious keratitis following corneal crosslinking are published. The most virulent pathogens were Pseudomonas aeruginosa and Acanthamoeba. Less virulent organisms were Escherichia coli and S. epidermidis. Two cases of herpes keratitis were described, suggesting the possibility of systemic antiviral prophylaxis before corneal crosslinking treatment. The most common risk factor of infections identified was postoperative incorrect patient behavior.     

Microbial keratitis in South India: influence of risk factors, climate, and geographical variation

PURPOSE: To determine the influence of risk factors, climate, and geographical variation on the microbial keratitis in South India. METHODS: A retrospective analysis of all clinically diagnosed infective keratitis presenting between September 1999 and August 2002 was performed. A standardised form was filled out for each patient, documenting sociodemographic features and information pertaining to risk factors. Corneal scrapes were collected and subjected to culture and microscopy. RESULTS: A total of 3,183 consecutive patients with infective keratitis were evaluated, of which 1,043 (32.77%) were found to be of bacterial aetiology, 1,095 (34.4%) were fungal, 33 (1.04%) were Acanthamoeba, 76 (2.39%) were both fungal and bacterial, and the remaining 936 (29.41%) were found to be culture negative. The predominant bacterial and fungal pathogens isolated were Streptococcus pneumoniae (35.95%) and Fusarium spp. (41.92%), respectively. Most of the patients (66.84%) with fungal keratitis were between 21 and 50 years old, and 60.21% of the patients with bacterial keratitis were older than 50 (p < 0.0001) (95% CI: 5.19-7.19). A majority of patients (64.75%) with fungal keratitis were agricultural workers (p < 0.0001) [odds ratio (OR): 1.4; 95% CI: 1.19-1.61], whereas bacterial keratitis occurred more commonly (57.62%) in nonagricultural workers (p < 0.0001) (OR: 2.88; 95% CI: 2.47-3.36). Corneal injury was identified in 2,256 (70.88%) patients, and it accounted for 92.15% in fungal keratitis (p < 0.0001) (OR: 7.7; 95% CI: 6.12-9.85) and 100% in Acanthamoeba keratitis. Injuries due to vegetative matter (61.28%) were identified as a significant cause for fungal keratitis (p < 0.0001) (OR: 23.6; 95% CI: 19.07-29.3) and due to mud (84.85%) for Acanthamoeba keratitis (p < 0.0001) (OR: 26.01; 95% CI: 3.3-6.7). Coexisting ocular diseases predisposing to bacterial keratitis accounted for 68.17% (p < 0.0001) (OR: 33.99; 95% CI: 27.37-42.21). The incidence of fungal keratitis was higher between June and September, and bacterial keratitis was less during this period. CONCLUSION: The risk of agricultural predominance and vegetative corneal injury in fungal keratitis and associated ocular diseases in bacterial keratitis increase susceptibility to corneal infection. A hot, windy climate makes fungal keratitis more frequent in tropical zones, whereas bacterial keratitis is independent of seasonal variation and frequent in temperate zones. Microbial pathogens show geographical variation in their prevalence. Thus, the spectrum of microbial keratitis varies with geographical location influenced by the local climate and occupational risk factors.     

Fungal keratitis in far north Queensland,Australia

Background: Aboriginals and Torres Strait Islanders form a significant proportion of the population in far north Queensland and are at increased risk for many eye conditions. This study describes the pattern of fungal keratitis seen at Cairns Base Hospital, far north Queensland, Australia. Methods: A retrospective review of all cases of culture positive fungal keratitis presenting between 1998 and 2008. The records of 17 patients were reviewed for epidemiological, risk factor, microbiological, treatment and outcome data. Results: The study included 16 eyes from 16 patients. Five (31.25%) patients were of Aboriginal and Torres Strait Islander descent. Pre‐disposing factors were ocular trauma (n = 7) and contact lens wear (n = 3). No patients were on topical steroids at presentation. All patients grew filamentous fungi with Fusarium the most common isolate (50%). Aspergillus, Curvularia and Lasiodiplodia theobromae were the next most common accounting for two cases each. Two patients developed corneal perforations, whereas two required penetrating keratoplasty and one required evisceration. Eight patients had a visual acuity of 6/18 or better at presentation and this increased to 13 patients at final follow up. Conclusions: A significant proportion of the patients presenting to Cairns Base Hospital with fungal keratitis are Indigenous. The very high percentage of cases due to filamentous fungi is similar to other tropical regions of the world. The very low rates of Candida infection and steroid use prior to presentation are in contrast to studies from temperate areas such as Melbourne and Philadelphia.     

Moraxella keratitis: predisposing factors and clinical review of 95 cases

AIM: To analyse the clinical presentation, identify predisposing risk factors and evaluate the outcome of treatment of Moraxella keratitis. METHODS: A retrospective analysis was carried out of culture-proved cases of Moraxella keratitis from hospital records during a 10-year period (from December 1995 to November 2005) at the Corneal Unit of the Royal Victorian Eye and Ear Hospital, Melbourne, Australia. RESULTS: 95 episodes of Moraxella keratitis were identified in 92 patients. 3 (3.2%) patients had recurrent keratitis. The mean age of the patients was 70 (range 17-93) years. Multiple predisposing factors were identified in 23 (24%) eyes, including corneal graft (n = 15), previous herpes keratitis (n = 15) and eye lid diseases (n = 15). Adjunctive procedures were carried out in 42 eyes. These included botulinum toxin injection (n = 17), tarsorraphy (n = 12), penetrating keratoplasty (n = 8), enucleation (n = 3), tissue adhesive and bandage contact lens (n = 4), and conjunctival flap (n = 5). Polymicrobial infection was present in 17 eyes. Final visual acuity was counting finger or less in 25 (26%) eyes. CONCLUSIONS: Local ocular predisposing factors play a major role in Moraxella keratitis. This infection has a poor visual outcome attributable to both the nature of the infection and the predisposing factors.     

Microbial keratitis in Waikato, New Zealand

Background: Bacterial keratitis is a potentially sight‐threatening condition. This study is performed to identify the common causative organisms for bacterial keratitis in Waikato region and the antibiotic sensitivities to these organisms. Design: Retrospective, observational, case series. Participants: The microbiology records of all patients with bacterial keratitis who presented to the Ophthalmology department, Waikato Hospital, New Zealand between January 2003 and December 2007. Methods: The corneal scrape results were reviewed. Antibiotic sensitivity for the organism was tested following National Committee for Clinical Laboratory Standards (NCCLS) method. Main Outcome Measures: In vitro laboratory susceptibility testing of ocular isolates to various antibiotics. Results: A total of 265 scrapes were performed. Gram stain was positive in 35 (13.2%) eyes. Positive culture was seen in 174 (65.6%) scrapes; 78.2% were Gram‐positive and 20.2% were Gram‐negative organisms. Most common Gram‐positive organisms were coagulase‐negative Staphylococci (40.8%) and Staphylococcus aureus (11.5%). Most common Gram‐negative organisms were Moraxalla species (8.0%) and Pseudomonas aeroginosa (3.4%). Of the bacterial organisms 99% were sensitive to ciprofloxacin. All Gram‐negative organisms and 95.5% Gram‐positive organisms were sensitive to tobramycin; 96.6% Gram‐positive organisms and 98.3% Gram‐negative organisms were sensitive to cefuroxime. Conclusions: Our results are comparable to other regions in New Zealand but the incidence of coagulase‐negative Staphylococcus is much higher in this region compared with other New Zealand studies. It seems appropriate to start patients with corneal ulcers initially on fluoroquinolone monotherapy while awaiting culture results.     

Big-bubble deep anterior lamellar keratoplasty for post-keratitis and post-traumatic corneal stromal scars

Background: Evaluation of outcomes of big‐bubble deep anterior lamellar keratoplasty in cases with post‐keratitis and post‐traumatic corneal scars. Design: Interventional case series. Participants: Patients with corneal stromal scarring secondary to healed infectious keratitis or trauma were recruited from the Corneal Clinic of the M. M. Joshi Eye Institute, Karnataka, India between August 2007 and December 2009. Methods: All patients underwent big‐bubble deep anterior lamellar keratoplasty surgery. Main Outcome Measures: Best‐corrected visual acuity, as well as intra‐ and postoperative complications. Results: Big‐bubble deep anterior lamellar keratoplasty was performed in 36 patients (25 males, 11 females) with post‐infectious keratitis (n = 22) and post‐traumatic (n = 14) corneal stromal scars sparing the Descemet's membrane and endothelium. Mean age was 39.7 ± 11.3 years (range: 22–58 years). Although a big bubble was achieved in all eyes (100%), intraoperative perforation of the Descemet's membrane occurred in six eyes (16%) during stromal dissection. Two cases required conversion to penetrating keratoplasty. A double anterior chamber occurred in the immediate postoperative period in three cases (8.3%). Raised intraocular pressure was seen in one eye. Mean preoperative best‐corrected visual acuity (0.03 ± 0.04) improved significantly at the end of 6 months follow‐up postoperatively (0.43 ± 0.20; P < 0.01, Wilcoxon signed‐ranks test). Corneal stromal graft rejection was noted in two cases (5.5%) during the first 3 months after surgery. Graft failure occurred in two cases (5.5%). Conclusions: Deep anterior lamellar keratoplasty using the big‐bubble technique is a viable option in cases with post‐infectious keratitis and post‐traumatic corneal stromal scarring with normal Descemet's membrane and endothelium.     

Corneal complications following abuse of topical anesthetics

PURPOSE: To describe corneal complications in three patients following abuse of topical anesthetics. MATERIALS AND METHODS: We describe one case with bilateral corneal perforation, another with unilateral corneal perforation and a third case of chronic keratitis following excessive use of topical anesthetics. RESULTS: Two patients continued to instill topical anesthetic drops despite all recommendations to stop. The result was a bilateral corneal perforation in the first case and a large unilateral descemetocele in the second. The third patient who had chronic toxic keratitis discontinued the anesthetic drops and after the appropriate treatment the cornea returned to normal. Corneal grafting and conjunctival flaps were used to seal the corneal perforation but the long-term anatomical and functional results were very poor. CONCLUSIONS: The initial presentation of this rare clinical entity creates difficulties in reaching a correct diagnosis. A presumed acanthamoeba keratitis is the first choice among many similar conditions. Thus abuse of topical ocular anesthetic drops should be included in the differential diagnosis of cases of chronic keratitis as it may masquerade as acanthamoeba keratitis. A current or past history of psychiatric and mental disorders or psychoactive substance abuse is important in the diagnosis. Functional and anatomical results after appropriate treatment are usually poor. Psychiatric counselling is extremely helpful and is in fact mandatory in the management of these patients.     

A longitudinal study of trends in keratitis in Australia

PURPOSE: To analyze the changes in risk factors, corneal culture results, antibiotic resistance, treatment, and clinical outcomes of patients with keratitis presenting to a major public hospital in Australia over a 5-year period. METHODS: A retrospective audit of all patients who had a corneal scraping between October 1999 and September 2004 at the Princess Alexandra Hospital. Clinical information was gathered from medical records and smear and culture results from the local microbiology database. The trends over time in patient demographics, keratitis risk factors, corneal culture results, antibiotic resistance, treatment, and clinical outcomes were analyzed by using linear regression. By using a moving average, we analyzed differences in the rate of culture of each causative organism for each month of the year with linear regression from the month of highest presentation. The mean of maximum temperatures on the days of presentation between different groups of organisms was compared. RESULTS: The proportion of patients presenting with keratitis related to contact lens wear increased significantly (12%-29%; P = 0.04) and with keratitis related to ocular surgery decreased significantly (18%-8%; P = 0.009) through the study. Antibiotic resistance of cultured bacteria to cephalothin increased significantly (2%-12%; P = 0.02), whereas resistance to ciprofloxacin and gentamicin remained at a low level throughout the study. There was significant variation in the monthly recovery of Pseudomonas aeruginosa (P = 0.04) and fungi (P = 0.02), which were cultured more frequently in summer months, whereas Streptococcus pneumoniae (P = 0.04) was more common in winter months than in other times of the year. Treatment with fluoroquinolones increased significantly (14%-40%; P = 0.002) through the study, and the rate of good outcomes also increased significantly (42%-72%; P = 0.02). CONCLUSIONS: In this series, keratitis related to contact lens wear became more frequent, whereas keratitis related to prior ocular surgery became less frequent. Different organism groups showed significant seasonal variations in their presentation, and bacterial resistance to cephalothin increased significantly.