"Demodicosis" Mimicking PreSeptal Cellulitis: Severe Periocular and Facial Inflammation Caused by "Normal" Skin Flora.

Due to their relatively high prevalence and commensalism, the pathogenicity of Demodex mites has been debated. Recent data, however, show Demodex to be associated with skin and ocular surface diseases such as rosacea, blepharitis, and keratitis. Here the authors report the first known case, to the best of the their knowledge, of Demodex infestation mimicking preseptal cellulitis in an adult human. A 29-year-old male bilaterally blind from advanced retinopathy of prematurity presented with a 2-month history of right-greater-than-left upper eyelid and periocular/cheek swelling, redness, and ocular discharge that did not resolve with oral antibiotics or oral steroids. Based on MRI findings, biopsies of the right lacrimal gland, right orbital fat, and right upper eyelid preseptal skin were obtained which revealed marked intrafollicular Demodex mite density and budding yeasts in the upper eyelid skin. This case serves to alert clinicians to this entity that may not otherwise be usually considered in ophthalmic clinical practice.

Role of Topical 5-Fluorouracil in Demodex -Associated Blepharitis.

PURPOSE: The aim of this study was to report clinical observations suggesting the efficacy of topical 1% 5-fluorouracil (5-FU) in treating Demodex -associated blepharitis. METHODS: An observational retrospective review of 13 eyes from 13 individuals with conjunctival neoplastic lesions and concomitant Demodex lash infestation that received topical 1% 5-FU eye drops. Patients underwent slit-lamp examination at each follow-up visit. Clinical photographs of the lash line were obtained after treatment initiation. In a subset of patients, lashes were epilated bilaterally and microscopically analyzed for presence of Demodex mites before and after treatment initiation. RESULTS: The mean age of the population was 68 ± 14 years (range: 30-84 years) and 92% were male. In all 13 patients, a marked reduction in cylindrical dandruff was noted in the treated eye by slit-lamp examination after 2 cycles of 5-FU. There was complete resolution of cylindrical dandruff in 10 of 13 treated eyes compared with 0 resolution of cylindrical dandruff in untreated eyes ( P = 0.0001). In the 6 patients who received epilation, the lashes from the treated eye showed no Demodex , whereas lashes from the fellow untreated eye revealed persistent Demodex . CONCLUSIONS: Topical 1% 5-FU shows efficacy in treating Demodex -associated blepharitis. Further studies are indicated to reproduce our findings and evaluate the potential use of 5-FU as a treatment ingredient.

Impact of Acanthamoeba Keratitis on the Vision-Related Quality of Life of Contact Lens Wearers.

PURPOSE: The aim of this study was to determine the impact of Acanthamoeba keratitis (AK) caused by contact lens (CL) use on vision-related quality of life (VRQOL) and the sociodemographic factors and disease outcome associated with VRQOL. METHODS: Sixty-one CL-associated AK cases and 59 asymptomatic CL wearers (mean age ±SD 39.4 ± 16.5 vs. 45.5 ± 15.2 yrs, P = 0.04) were recruited from Moorfields Eye Hospital and Institute for Optometry, London. AK cases were surveyed during active disease and were stratified into "poor" and "good" outcomes based on clinical features. VRQOL was measured using Rasch-transformed scores from the Emotional, Mobility, and Reading domains of the 32-item Impact of Visual Impairment questionnaire. AK cases were compared with controls and "poor" outcomes compared with "good" with multivariable linear regression. Multivariable linear regression models were also used to identify the sociodemographic factors and disease outcome associated with VRQOL. RESULTS: AK was associated with significant and substantial reductions in all 3 evaluated domains of VRQOL (Reading -59.6%, Mobility -59.8%, and Emotional -66.2%) compared with controls, independent of sociodemographic factors. Patients with AK who experienced poor outcomes, those who were of British White race (compared with all other races) and female, had lower VRQOL scores across all domains. Patients with AK with lower incomes scored worse on Reading and Mobility domains, whereas those with lower education had poorer Emotional scores. CONCLUSIONS: AK has a considerable detrimental impact on VRQOL. Clinicians should consider the importance of referring patients with AK for rehabilitative support and counseling as part of active disease management.

PHILOPHTHALMUS HECHINGERI N. SP. (DIGENEA: PHILOPHTHALMIDAE), A HUMAN-INFECTING EYE FLUKE FROM THE ASIAN MUD SNAIL, BATILLARIA ATTRAMENTARIA.

Two cases of human philophthalmosis have been reported in Japan. Gravid flukes removed from the eyes of the patients were broken, but their morphological characteristics suggest that an unknown species of the genus Philophthalmus is involved as a pathogen for humans. The mitochondrial DNA barcode of the human eye fluke enabled us to discover its larval stage from the Japanese mud snail, Batillaria attramentaria. The discovered cercaria had previously been temporarily described as "Philophthalmid sp. I." In this study, we examined the infection status of B. attramentaria with Philophthalmid sp. I found on a muddy seashore of the Seto Inland Sea, Japan, and the resulting metacercariae were experimentally administered to Japanese quails to develop them into the gravid adult stage. The complete specimens of the adult and larval stages allowed us to describe a new species. Based on morphological and molecular analyses, Philophthalmus hechingeri n. sp. is proposed for the human-infecting eye fluke in Japan. The natural definitive hosts of the new species are unknown. However, the habitat of B. attramentaria suggests that shorebirds (seagulls, sandpipers, and plovers) might be the possible candidates.

Amoebicidal Activity of Poly-Epsilon-Lysine Functionalized Hydrogels.

Purpose: To determine the amoebicidal activity of functionalized poly-epsilon-lysine hydrogels (pɛK+) against Acanthamoeba castellanii. Methods: A. castellanii trophozoites and cysts were grown in the presence of pɛK solution (0-2.17 mM), pɛK or pɛK+ hydrogels, or commercial hydrogel contact lens (CL) for 24 hours or 7 days in PBS or Peptone-Yeast-Glucose (PYG) media (nutrient-deplete or nutrient-replete cultures, respectively). Toxicity was determined using propidium iodide and imaged using fluorescence microscopy. Ex vivo porcine corneas were inoculated with A. castellanii trophozoites ± pɛK, pɛK+ hydrogels or commercial hydrogel CL for 7 days. Corneal infection was assessed by periodic acid-Schiff staining and histologic analysis. Regrowth of A. castellanii from hydrogel lenses and corneal discs at 7 days was assessed using microscopy and enumeration. Results: The toxicity of pɛK+ hydrogels resulted in the death of 98.52% or 83.31% of the trophozoites at 24 hours or 7 days, respectively. The toxicity of pɛK+ hydrogels resulted in the death of 70.59% or 82.32% of the cysts in PBS at 24 hours or 7 days, respectively. Cysts exposed to pɛK+ hydrogels in PYG medium resulted in 75.37% and 87.14% death at 24 hours and 7 days. Ex vivo corneas infected with trophozoites and incubated with pɛK+ hydrogels showed the absence of A. castellanii in the stroma, with no regrowth from corneas or pɛK+ hydrogel, compared with infected-only corneas and those incubated in presence of commercial hydrogel CL. Conclusions: pɛK+ hydrogels demonstrated pronounced amoebicidal and cysticidal activity against A. castellanii. pɛK+ hydrogels have the potential for use as CLs that could minimize the risk of CL-associated Acanthamoeba keratitis.

Efficacy of Topical Ivermectin 1% in the Treatment of Demodex Blepharitis.

PURPOSE: The purpose of this study was to evaluate the efficacy of topical ivermectin 1% cream application on the eyelashes in combination with eyelid hygiene in the treatment of Demodex blepharitis. METHODS: One hundred two eyes of 102 patients with symptomatic Demodex blepharitis were divided into 2 groups according to the use of topical ivermectin in this retrospective case-control study. The ivermectin group (n = 51) applied topical ivermectin 1% cream on the eyelashes for 15 minutes once weekly, but the control group (n = 51) did not. In both groups, eyelid hygiene was performed once daily. The Standard Patient Evaluation of Eye Dryness (SPEED) symptom questionnaire score, Oxford staining score, eyelid debris, eyelid redness/swelling, and telangiectasia were assessed during the follow-up visits. RESULTS: The mean follow-up periods of the ivermectin and control groups were 15.1 ± 9.7 weeks and 14.8 ± 8.6 weeks, respectively. The SPEED score and eyelid debris grade were significantly improved in both groups during the follow-up, although the SPEED score and eyelid debris grade showed greater changes in the ivermectin group than in the control group. The Oxford staining score, eyelid redness/swelling grade, and telangiectasia grade were significantly improved only in the ivermectin group but not in the control group. CONCLUSIONS: In patients with Demodex blepharitis, the use of topical ivermectin 1% cream for 15 minutes once weekly in addition to eyelid hygiene had more significantly improved symptoms, ocular surface staining, eyelid debris, redness/swelling, and telangiectasia as compared with eyelid hygiene alone. These findings support the efficacy of topical ivermectin 1% cream application in the treatment of Demodex blepharitis.

Thelazia callipaeda in Slovakia - From sporadic cases to endemic areas.

Spirurid nematode Thelazia callipaeda, transmitted by the fruit fly Phortica variegata, is a causative agent of an ocular parasitic disease called also canine thelaziosis. Dogs, cats, and wild canids are considered the primary definitive hosts for the parasite, but humans may also serve as aberrant definitive hosts. For long decades the geographic range of T. callipaeda was strictly limited to the territory of Asia, but after the year 2000, the parasite began to spread rapidly through Europe. The first autochthonous infections of dogs and foxes in Slovakia were recorded in 2016. In the present study, the results of a whole-area surveillance for canine thelaziosis are reported. Altogether, 142 cases of infection caused by T. callipaeda were diagnosed by veterinarians in dogs between 2016 and the first quarter of 2021, and two cases of feline thelaziosis were recorded. The majority of the dogs showed mild ocular signs manifested by conjunctivitis; 8.5% of them suffered from more serious mucopurulent discharge, and in two dogs corneal ulceration was recorded. The screening revealed increasing trends in the occurrence of canine thelaziosis from both a temporal and spatial point of view and unambiguously confirms the endemic status of T. callipaeda in Slovakia with the prospect of its further expansion.

DISTRIBUTION AND DIVERSITY OF DIPLOSTOMIDS IN NEW ZEALAND.

Parasitism is one of the most common consumer strategies and contributes a large portion to biological diversity. Trematodes in the family Diplostomidae are common in freshwater ecosystems worldwide, often residing in the eyes or brain of fish and then infecting fish-eating birds as adults. As a result, some species have broad geographic distributions due to the bird host's motility. In contrast to the cosmopolitan nature of diplostomids, only a single species, Tylodelphys darbyi, has been identified in New Zealand to date, and only from the South Island. Tylodelphys darbyi has a 3-host life cycle consisting of an unidentified snail, a freshwater fish (Gobiomorphus cotidianus), and the Australasian crested grebe (Podiceps cristatus australis). To date, T. darbyi has been found in 2 locations, Lake Hayes, in the eyes of G. cotidianus, and Lake Wanaka, adults recovered from grebes. Considering the near ubiquity of the fish host in New Zealand, it is likely the bird, listed as nationally vulnerable, is the limiting factor in the range of T. darbyi. Up to 10 G. cotidianus were sampled from 10 mountain lakes known to have populations of grebe in the Otago and Canterbury regions of New Zealand's South Island. The eyes of all fish were examined and any metacercariae present were set aside for genetic analysis. In addition to expanding the known range of T. darbyi to at least 4 water bodies across the South Island, 2 new taxa of diplostomid were identified. A lens-infecting metacercariae clustered with Diplostomum spathaceum, while the metacercariae from the humor clustered with Diplostomum baeri.

Effect of ocular demodicosis on the stability of the tear film and the tear break up time.

The aim of the study was to analyze the correlation between the presence of Demodex mites in the hair follicles of patients' eyelashes and the stability and break up time of the tear film assessed with the Non-Invasive Tear Break Up Times (NIBUT) method. 319 patients were included in the study (195 women, 124 men). The patients were divided into two groups: those with Demodex infestation and without visible symptoms of eyelid or eye surface diseases, and asymptomatic non-infested patients. The NIBUT analysis was performed with a 5 M keratograph (oculus). Non-invasive tests were performed to identify the first and mean values of the tear break up time. The first and mean tear break up time in the Demodex-infested group was lower than in the non-infested subjects. The difference was a highly statistically significant. There was a significant correlation with the age of the patients for the first break up time. The first break up time in both eyes decreased with the age of the Demodex-infested and non-infested patients. The NIBUT analyses indicate the impact of Demodex mites on the tear film stability. This may suggest possible association of demodicosis with dry eye syndrome.

Clinical characteristics of Demodex-associated recurrent hordeola: an observational, comparative study.

Our study evaluated the association between Demodex infestation and recurrent hordeola and examined the clinical features associated with these eyelid lesions. This was an observational, comparative study. We reviewed 250 patients and divided them into the recurrent hordeolum (n = 153) and control (n = 97) groups. Demodex infestation was detected by epilating eyelashes around the lesion/s and viewing them under a light microscope. Patient medical records and photographs were retrospectively analyzed to identify the clinical characteristics of Demodex-associated recurrent hordeola. Demodex was detected in 91 (59.5%) and 17 (17.5%) patients in the recurrent hordeolum and control groups (p < 0.001), respectively. In the recurrent hordeolum group, Demodex mites were found in 74 (68.5%) and 17 (37.8%) of the adult and pediatric patients (p < 0.001), respectively. Among patients with recurrent hordeola, patients in their 20s were most likely to have concomitant Demodex infestation. Patients with Demodex infestations were also more likely to develop recurrent lesions within a shorter period of time from the primary incision and curettage. The most common presentation of Demodex-associated recurrent lesions was external hordeola (67%) (p = 0.002). Demodex infestation may cause recurrent hordeola in adults and children. These mites may play a greater role in the development of lesions in adult patients. The strongest association between Demodex infestation and recurrent lesions was seen in patients in their 20s. Our results suggest that if the hordeola recur within a short period of time with the clinical characteristics of external location of eyelid, multiple numbers of lesions, or anterior blepharitis, eyelash epilation should be performed to identify the presence of Demodex mites.

Ocular Dirofilariasis Case in Thailand Confirmed by Molecular Analysis to Be Caused by Dirofilaria immitis.

A rare ocular dirofilariasis case along with the clinical characteristics, treatment, and outcome is reported. A whitish roundworm (10.6 cm long and 0.5 mm width) emerged from the pterygium, a triangular tissue growth on the cornea of the eye, of a male patient. The worm had a rounded anterior part, mouth without lips, smooth cuticular surface, and short rounded posterior tail with spicules: these features suggested that it was a male Dirofilaria sp. Molecular identification confirmed that the worm belonged to Dirofilaria immitis. This is the first molecular confirmation that D. immitis is a causative agent of ocular dirofilariasis in Thailand: dirofilariasis is a newly emerging zoonotic disease. Physicians should be alert to zoonotic filarial worms and knowledgeable about treatment of this disease.

Collarette Elimination and Demodex Mite Eradication with Topical Lotilaner Ophthalmic Solution, 0.25.

Purpose: To evaluate the efficacy of topical lotilaner ophthalmic solution, 0.25%, in patients with Demodex blepharitis. Methods: Eighteen adults with Demodex blepharitis, defined as >10 collarettes on the upper lid and/or mite density of ≥1.5 mites per lash (upper and lower), were treated bid for 42 days with the topical lotilaner ophthalmic solution, 0.25%. Contact lens wear, artificial eyelashes, and lid structural abnormalities were among the exclusion criteria. No other antibacterial, antiparasitic, or anti-inflammatory treatment or lid hygiene products were permitted. One eye of each patient was selected for analysis and assessed on day 7, 14, 28, and 42. Collarettes were graded at each visit, and mite density was evaluated by microscopy at each visit except day 7. Outcome measures were collarette elimination (≤2 lashes with collarettes) and mite eradication (0 mites). Drop tolerability, adverse events, visual acuity, and slit-lamp biomicroscopy were assessed. Results: Collarette elimination was achieved in 13/18 participants (72.2%) by day 42. Mean collarette grade (upper lid) declined from 3.56 ± 0.17 to 0.28 ± 0.11. Mite eradication was achieved in 14/18 participants (77.8%) by day 42. Mean mite density decreased from 2.63 ± 0.39 to 0.12 ± 0.08 mites/lash. Participants reported good tolerability. Adverse events were mild and transient and did not result in treatment discontinuation. Conclusion: Six weeks of at-home topical therapy with the lotilaner ophthalmic solution, 0.25%, was effective in eliminating the most common objective signs of Demodex blepharitis, with a collarette elimination rate of 72% and mite eradication in 78% of eyes by day 42. ISRCTN registration #: 24398865.

Corneal Effects of Tea Tree Oil.

PURPOSE: The purpose of this study is to report a case of corneal epithelial defects resulting from topical treatment of blepharitis with tea tree oil (TTO). METHODS: A 44-year-old man with a 1 year history of blepharitis non-responsive to eyelid hygiene was found to have signs of Demodex infestation. He was treated with a topical, off-label 50% TTO solution. Shortly afterward, the patient complained of bilateral ocular discomfort. RESULTS: Slit-lamp examination revealed conjunctival injection and a corneal epithelial defect in both eyes. Treatment with lubricant, antibiotic, and steroid eye drops as well as bandage contact lenses was required to facilitate corneal healing. CONCLUSIONS: Topical use of off-label, 50% concentration TTO can result in corneal epithelial defects. Eye care professionals should remain aware of this risk and only use approved, low-concentration TTO products when treating Demodex-related blepharitis.

Zoonotic Thelazia californiensis in dogs from New Mexico, USA, and a review of North American cases in animals and humans.

Thelazia californiensis is a spirurid nematode found in the conjunctival sac of domestic and wild animals, including humans, across the western United States of America. Herein, we report two cases of thelaziosis by T. californiensis in dogs from New Mexico, United States, based on integrated morphological and molecular approaches. Nematode specimens collected from the conjunctiva of both dogs were identified as T. californiensis based on morphology. Our study substantially expands the knowledge on morphometry of this nematode species. Therefore, these data will be useful for accurate diagnosis of thelaziosis in domestic animals, wildlife and humans in North America, using classical, microscopy-based methods. We characterized for the first time the mitochondrial cytochrome c-oxidase subunit 1 (COI) and 12S genes of T. californiensis. While these markers support the validity of T. californiensis, they were not very informative for elucidating the phylogenetic relationships among Thelazia species. Nevertheless, the characterization of these diagnostic markers for T. californiensis will be useful for studies on the epidemiology, molecular xenomonitoring of fanniid vectors, and population genetics of this multi-host, zoonotic parasite.

Classification Criteria for Toxoplasmic Retinitis.

PURPOSE: To determine classification criteria for toxoplasmic retinitis. DESIGN: Machine learning of cases with toxoplasmic retinitis and 4 other infectious posterior uveitides / panuveitides. METHODS: Cases of infectious posterior uveitides / panuveitides were collected in an informatics-designed preliminary database, and a final database was constructed of cases achieving supermajority agreement on diagnosis, using formal consensus techniques. Cases were split into a training set and a validation set. Machine learning using multinomial logistic regression was used on the training set to determine a parsimonious set of criteria that minimized the misclassification rate among the infectious posterior uveitides / panuveitides. The resulting criteria were evaluated on the validation set. RESULTS: Eight hundred three cases of infectious posterior uveitides / panuveitides, including 174 cases of toxoplasmic retinitis, were evaluated by machine learning. Key criteria for toxoplasmic retinitis included focal or paucifocal necrotizing retinitis and either positive polymerase chain reaction assay for Toxoplasma gondii from an intraocular specimen or the characteristic clinical picture of a round or oval retinitis lesion proximal to a hyperpigmented and/or atrophic chorioretinal scar. Overall accuracy for infectious posterior uveitides / panuveitides was 92.1% in the training set and 93.3% (95% confidence interval 88.2, 96.3) in the validation set. The misclassification rates for toxoplasmic retinitis were 8.2% in the training set and 10% in the validation set. CONCLUSIONS: The criteria for toxoplasmic retinitis had a low misclassification rate and seemed to perform sufficiently well for use in clinical and translational research.

American Academy of Optometry Microbial Keratitis Think Tank.

SIGNIFICANCE: Think Tank 2019 affirmed that the rate of infection associated with contact lenses has not changed in several decades. Also, there is a trend toward more serious infections associated with Acanthamoeba and fungi. The growing use of contact lenses in children demands our attention with surveillance and case-control studies. PURPOSE: The American Academy of Optometry (AAO) gathered researchers and key opinion leaders from around the world to discuss contact lens-associated microbial keratitis at the 2019 AAO Annual Meeting. METHODS: Experts presented within four sessions. Session 1 covered the epidemiology of microbial keratitis, pathogenesis of Pseudomonas aeruginosa, and the role of lens care systems and storage cases in corneal disease. Session 2 covered nonbacterial forms of keratitis in contact lens wearers. Session 3 covered future needs, challenges, and research questions in relation to microbial keratitis in youth and myopia control, microbiome, antimicrobial surfaces, and genetic susceptibility. Session 4 covered compliance and communication imperatives. RESULTS: The absolute rate of microbial keratitis has remained very consistent for three decades despite new technologies, and extended wear significantly increases the risk. Improved oxygen delivery afforded by silicone hydrogel lenses has not impacted the rates, and although the introduction of daily disposable lenses has minimized the risk of severe disease, there is no consistent evidence that they have altered the overall rate of microbial keratitis. Overnight orthokeratology lenses may increase the risk of microbial keratitis, especially secondary to Acanthamoeba, in children. Compliance remains a concern and a significant risk factor for disease. New insights into host microbiome and genetic susceptibility may uncover new theories. More studies such as case-control designs suited for rare diseases and registries are needed. CONCLUSIONS: The first annual AAO Think Tank acknowledged that the risk of microbial keratitis has not decreased over decades, despite innovation. Important questions and research directions remain.

A Helminth Survey of Northern Bobwhite Quail (Colinus virginianus) and Passerines in the Rolling Plains Ecoregion of Texas.

The Northern bobwhite quail (Colinus virginianus) is a popular game bird that has been experiencing a well-documented decline throughout Texas since the 1960s. While much of this decline has been attributed to habitat loss and fragmentation, recent studies have identified other factors that may also contribute to decreasing quail populations. Parasites, in particular, have become increasingly recognized as possible stressors of quail, and some species, particularly the eyeworm (Oxyspirura petrowi) and cecal worm (Aulonocephalus pennula) are highly prevalent in Texas quails. Eyeworm infection has also been documented in some passerines, suggesting helminth infection may be shared between bird species. However, the lack of comprehensive helminth surveys has rendered the extent of shared infection between quail and passerines in the ecoregion unclear. Thus, helminth surveys were conducted on bobwhite, scaled quail (Callipepla squamata), Northern mockingbirds (Mimus polyglottos), curve-billed thrashers (Toxistoma curvirostre), and Northern cardinals (Cardinalis cardinalis) to contribute data to existing parasitological gaps for birds in the Rolling Plains ecoregion of Texas. Birds were trapped across 3 counties in the Texas Rolling Plains from March to October 2019. Necropsies were conducted on 54 individuals (36 quail and 18 passerines), and extracted helminths were microscopically identified. Nematode, cestode, and acanthocephalan helminths representing at least 10 helminth species were found. Specifically, A. pennula and O. petrowi had the highest prevalence, and O. petrowi was documented in all of the study species. This research adds to the body of knowledge regarding parasitic infections in quail and passerines of the Rolling Plains ecoregion and highlights the potential consequences of shared infection of eyeworms among these bird species.

Delayed diagnoses of Acanthamoeba keratitis at a tertiary care medical centre.

PURPOSE: To determine the prevalence and reasons for delays in diagnosis in patients with Acanthamoeba keratitis (AK) presenting to Wilmer Eye Institute, Baltimore, Maryland. METHODS: This retrospective study analysed all patients with culture-positive AK seen between 2012 and 2019 at a tertiary referral centre. Patient demographic information, clinical history, risk factors, symptom duration, referral patterns, slit lamp examination findings, visual acuity and need for surgery were collected. RESULTS: The study included 45 eyes of 43 patients. On average, patients were symptomatic for 52.6 days before culture collection. Thirty-one percent of patients were diagnosed within 28 days of symptom onset while 69% were diagnosed after 28 days. Before presentation to a tertiary care centre, 69% of patients were evaluated by an ophthalmologist outside of this institution and 27% were evaluated by a provider other than an ophthalmologist. AK was most commonly misdiagnosed as herpetic keratitis, occurring in 38% of patients. The strongest risk factor for AK was contact lens use. Only 11% of patients presented with the classic ring infiltrate and 82% had pain. Patients with an early versus late diagnosis had a mean Snellen visual acuity (VA) of 20/224 versus 20/296 at presentation (p = 0.33) and a mean Snellen VA of 20/91 versus 20/240 at final visit (p = 0.07). 11% of patients required a therapeutic penetrating keratoplasty. CONCLUSION: Delayed diagnosis of AK in our cohort occurred due to a misdiagnosis as herpetic keratitis, non-specific clinical signs including the lack of pain in a number of patients, and a delay in referral to a tertiary care centre. Any contact lens wearer with an atypical keratitis should be referred promptly for Acanthamoeba cultures.