Purpose
To compare clinical characteristics, microbiological profiles, treatment strategies, and outcomes between contact lens–associated (CL) and noncontact lens–associated (non-CL) fungal keratitis.
Design
Retrospective, comparative clinical cohort study.
Methods
A review of culture-proven fungal keratitis treated at a tertiary referral center between 2018 and 2025 was conducted. Cases were categorized as CL or non-CL–associated. Demographic, clinical, microbiological, treatment, and outcome data were analyzed and compared between groups.
Results
Thirty-seven eyes were included, comprising 16 CL and 21 non-CL cases. CL users presented earlier than non-CL patients (median 7 vs 14 days, P =.007) and had fewer associated ocular risk factors (31% vs 81%, P =.001). Baseline visual acuity and infiltrate size did not differ significantly between groups. Candida species were isolated in 21% cases, Fusarium in 16% and Aspergillus in 8%. Fusarium (19% vs 13%) and Candida (24% vs 19%) infections were slightly more frequent in non-CL cases. Overall, filamentous fungi were the predominant organism group. Topical voriconazole was the most frequently used antifungal agent (78%). All CL-associated cases resolved with medical therapy alone, with a median time to resolution of 38 days (IQR 22-58). In contrast, 76% of non-CL cases resolved medically (median 42 days, IQR 32-76), while 23% required therapeutic keratoplasty ( P =.04). Final visual acuity was comparable between groups (logMAR 0.2 vs 0.5, P =.56).
Conclusion
Contact lens–associated fungal keratitis is characterized by earlier presentation and fewer underlying ocular comorbidities, with favorable outcomes achieved through medical therapy alone. Despite similar microbiological profiles and treatment approaches, noncontact lens–associated fungal keratitis more frequently follows a complicated course requiring surgical intervention.
INTRODUCTION
Fungal keratitis is a vision-threatening corn-eal infection associated with substantial morbidity and often poor visual outcomes, even with the availability of effective antifungal drugs. Compared with bacterial keratitis, fungal keratitis is more frequently associated with delays in diagnosis, limited treatment options, and a higher need for surgical interventions. While it remains a leading cause of corneal blindness in tropical regions, its epidemiology in developed settings differs and is comparatively less well defined. , In the United States, fungal keratitis has historically accounted for a minority of microbial keratitis cases; however, shifts in epidemiologic patterns have been observed over time. Notable geographic variation exists, with higher prevalence reported in warmer and more humid regions of the country. , Additionally, contact lens wear has increasingly emerged as a significant risk factor in U.S. cohorts, raising concern about its growing role in the changing landscape of fungal keratitis. , Contact lens–associated fungal keratitis has drawn increasing attention, particularly following prior outbreaks and reports identifying a substantial proportion of affected contact lens wearers. , The aims of this study were to characterize the demographic, clinical, microbiological, and treatment features of fungal keratitis over an 8-year period at a tertiary referral center in the northeastern United States, and to cf contact lens–associated with non–contact lens–associated cases.
METHODS
STUDY DESIGN AND PATIENT SELECTION
A retrospective, comparative clinical cohort study was conducted at the University of Pittsburgh Medical Center, a tertiary referral center in Pennsylvania, United States. The study was approved by the University of Pittsburgh Institutional Review Board and was compliant with the Health Insurance Portability and Accountability Act (HIPAA). Medical records of patients diagnosed with microbial keratitis between January 1, 2018, and December 31, 2025, were reviewed. Patients with microbiologically confirmed fungal keratitis were included. Confirmation required a positive culture from corneal specimens obtained via scraping, biopsy, or tissue collected during therapeutic keratoplasty. Additional inclusion criteria were complete microbiological data and at least 1 documented follow-up visit. Cases were categorized as contact lens-associated (CL group) and noncontact lens-associated (non-CL group) fungal keratitis.
DATA COLLECTION
Baseline demographic variables included age, sex, laterality, and duration from symptom onset to presentation. Ocular risk factors, including trauma, prior corneal surgery, and compromised ocular surface disease, were recorded. Compromised ocular surface conditions included neurotrophic keratopathy, dry eye disease, lagophthalmos, and recurrent corneal erosions. Clinical characteristics at presentation included best-corrected visual acuity, infiltrate size, depth of stromal involvement, ulcer location, and associated findings such as hypopyon, corneal thinning, perforation, pigmentation, and posterior segment involvement. Infiltrate size was calculated as the geometric mean of the longest diameter and its perpendicular measurement. Ulcers within the central 5 mm of the cornea were categorized as “central” while the rest were labelled as “peripheral” ulcers. Patients who had ulcers that overlapped these areas were categorized as “both.”
Microbiological data collected included smear results, culture findings, and the presence of polymicrobial infection. Treatment-related variables comprised prior therapy, initial antimicrobial regimen, use of systemic medications, and adjunctive procedures, including intrastromal or intracameral drug administration. Given the 8-year study period, treatment decisions reflected the discretion of the treating physician and may have evolved over time with changes in clinical practice.
OUTCOME MEASURES
The primary outcome was the proportion of cases in each group that resolved with medical therapy alone vs those requiring surgical intervention. Secondary outcomes included time to resolution and final best-corrected visual acuity.
STATISTICAL ANALYSIS
Continuous variables were reported as medians and IQRs (IQR), and categorical variables as frequencies and percentages. Comparisons between the groups were performed using chi-square tests, Fisher-exact tests, or Mann-Whitney U tests as appropriate. A P -value <.05 was considered statistically significant. Statistical analyses were conducted using R-Studio Desktop Version 4.3.0 [R-Studio Team (2023). R-Studio: Integrated Development for R. R-Studio, PBC, Boston, MA URL http://www.rstudio.com/ ].
RESULTS
BASELINE CHARACTERISTICS
A total of 37 patients met the inclusion criteria, including 16 CL users and 21 non-CL users. Among the 16 CL users, poor CL hygiene practices were noted in 10 patients, including CL overwear, sleeping in lenses, and showering while wearing lenses. Fifteen patients wore soft CLs, including 3 bandage lenses, while 1 patient wore a scleral lens. The median age of the cohort was 53.0 years. CL users were younger than non-CL users (47.5 vs 55.0 years), although this difference did not reach statistical significance ( P =.18). Gender distribution was comparable between the 2 groups (male: 44% in the CL group vs 52% in the non-CL group, P =.60).
The median duration from symptom onset to presentation was significantly shorter in CL users compared with non-CL users (7 vs14 days, P =.007). Ocular risk factors unrelated to CL use were present in 59% of patients overall, with some individuals having more than 1 risk factor. The prevalence of these risk factors was significantly higher in the non-CL group (17/21; 81%) than in the CL group (5/16; 31%; P =.001). Prior ocular surgery was the most commonly identified risk factor in both groups. In the CL group, 3 patients had a history of ocular surgery, including 2 who had undergone PK and one who had undergone laser-assisted in situ keratomileusis (LASIK). In the non-CL group, 7 patients had a history of ocular surgery, including 4 with prior LASIK, one with both LASIK and endothelial keratoplasty, one with prior PK, and one with a history of radial keratotomy. Corneal surface compromise was identified in 7 patients across the cohort. In the CL group, 1 patient was post-LASIK, and one had neurotrophic keratopathy. In the non-CL group, 4 patients had neurotrophic keratopathy, and one had recurrent corneal erosion. One patient in each group had coexisting autoimmune disease (scleroderma in CL users, Sjogren’s disease in non-CL users). Prior antibiotic exposure was documented in 10 of 16 patients (62.5%) in the CL group and 21 of 21 patients (100%) in the non-CL group. Long-term antibiotic use was reported in 2 and 5 patients, respectively, with no significant difference between groups ( P =.81). Corticosteroid use was documented in 10 of 16 patients (62.5%) in the CL group and 11 of 21 patients (52.4%) in the non-CL group. Among these patients, 4 and 3, respectively, were receiving long-term corticosteroid therapy before the onset of infection ( P =.45). Baseline characteristics are summarized in Table 1 .
TABLE 1
Comparison of Demographic and Clinical Characteristics Between CL and Non-CL Users
| Parameters | Total | CL Users | Non-CL Users | P -Value |
|---|---|---|---|---|
| N = 37 | N = 16 | N = 21 | ||
| Age (y), median (IQR) | 53.0 (42.5-60.5) | 47.5 (38.5-55.8) | 55.0 (42.5-67.5) | .18 |
| Gender (n, %) | ||||
| Male | 18 (49) | 7 (44) | 11 (52) | .60 |
| Female | 19 (51) | 9 (56) | 10 (48) | |
| Duration from symptom onset to presentation (d), median (IQR) | 12 (7-21) | 7 (3-14) | 14 (12-37) | .007 |
| Visual acuity at presentation (logMAR), median (IQR) | 0.6 (0.2-1.8) | 0.4 (0.2-0.9) | 0.8 (0.3-2.4) | .29 |
| Ocular risk factor | ||||
| Present | 22 (59) | 5 (31) | 17 (81) | .001 |
| Surgery | 10 (27) | 3 (19) | 7 (33) | |
| Trauma | 8 (22) | 2 (13) | 6 (29) | |
| Compromised cornea | 7 (19) | 2 (13) | 5 (24) | |
| Systemic risk factor (n, %) | – | |||
| Sjogren’s disease | 1 (3) | 0 (0) | 1 (5) | |
| Myasthenia gravis | 1 (3) | 0 (0) | 1 (5) | |
| Scleroderma | 1 (3) | 1 (6) | 0 (0) | |
| Mean geometric size of infiltrate (mm), median (IQR) | 2.3 (1.5-3.1) | 2.4 (1.2-3.0) | 2.1 (1.5-3.5) | .92 |
| Location of corneal infiltrate (n, %) | ||||
| Central | 16 (43) | 9 (56) | 7 (33) | .12 |
| Peripheral | 15 (41) | 6 (38) | 9 (43) | |
| Both | 4 (11) | 0 (0) | 4 (19) | |
| N/A | 2 (5) | 1 (6) | 1 (5) | |
| Hypopyon (n, %) | 9 (24) | 3 (19) | 6 (29) | .49 |
| Pigmentation (n, %) | 2 (5) | 1 (6) | 1 (5) | – |
| Stromal thinning (n, %) | 5 (14) | 0 (0) | 5 (24) | .07 |
| Posterior segment involvement (n, %) | 1 (3) | 0 (0) | 1 (5) | – |
| Surgical interventions | ||||
| Intrastromal and/or intracameral | 2 (5) | 0 (0) | 2 (10) | .20 |
| antifungal injections | ||||
| TPK | 5 (14) | 0 (0) | 5 (24) | .04 |
| Optical PK | 4 (11) | 0 (0) | 4 (19) | .06 |
CL = contact lens; IQR = interquartile range, N/A = Not available, PK = penetrating keratoplasty, TPK = therapeutic penetrating keratoplasty.
CLINICAL CHARACTERISTICS
At presentation, median visual acuity was comparable between the 2 groups (0.4 logMAR in CL users vs 0.8 logMAR in non-CL users, P =.29). Mean geometric infiltrate size did not differ significantly (2.4 mm in CL users vs 2.1 mm in non-CL users, P =.92). Central corneal involvement was more common in CL users (56%) compared with non-CL users (33%), though this difference was not statistically significant ( P =.12). The prevalence of hypopyon did not differ significantly between CL users and non-CL users (19% vs 29%, P =.49). Stromal thinning was observed exclusively in the non-CL group (24%), demonstrating a trend toward statistical significance ( P =.07).
MICROBIOLOGICAL FEATURES
On smear examination, hyphal elements were the most frequent finding overall (43%), with similar rates among CL users (50%) and non-CL users (38%). Yeast forms were less commonly detected (14%) and more frequently observed in the non-CL group (19% vs 6%). On culture, Candida spp. were isolated in 21% of cases, Fusarium spp. in 16% and Aspergillus spp. in 8%, with filamentous fungi accounting for the majority of infections. Fusarium (19% vs 13%) and Candida (24% vs 19%) infections were slightly more frequent in non-CL cases. Bacterial co-infection was present in 16% of cases, most commonly involving coagulase-negative Staphylococcus . CL solution culture was performed in 1 patient and yielded fungal growth. CLs were cultured in 2 patients, 1 culture grew Diphtheroids and the other was negative. Microbiological findings are summarized in Table 2 .
TABLE 2
Comparison of Microbiological Results Between CL and Non-CL Users
| Microbiology | Total Number of Eyes, n (%) | CL Users | Non-CL Users | P -Value |
|---|---|---|---|---|
| N = 16, n (%) | N = 21, n (%) | |||
| Smear | ||||
| Hyphae | 16 (43) | 8 (50) | 8 (38) | .49 |
| Yeast | 5 (14) | 1 (6) | 4 (19) | |
| Negative | 16 (43) | 7 (44) | 9 (43) | |
| Culture | ||||
| Fusarium species | 6 (16) | 2 (13) | 4 (19) | .59 |
| Candida species | .71 | |||
| Candida albicans | 4 (11) | 1 (6) | 3 (14) | |
| Candida dubliniensis | 2 (5) | 2 (13) | 0 (0) | |
| Candida parapsilosis | 2 (5) | 0 (0) | 2 (10) | |
| Aspergillus species | .39 | |||
| Aspergillus flavus | 1 (3) | 1 (6) | 0 (0) | |
| Aspergillus fumigatus | 2 (5) | 1 (6) | 1 (5) | |
| Sterile mycelia | 4 (11) | 1 (6) | 3 (14) | .40 |
| Acremonium species | 3 (8) | 1 (6) | 2 (10) | .39 |
| Alternaria species | 2 (5) | 2 (13) | 0 (0) | .27 |
| Bipolaris species | 2 (5) | 1 (6) | 1 (5) | – |
| Scedosporium species | 2 (5) | 0 (0) | 2 (10) | .27 |
| Chrysonilia sitophila | 1 (3) | 0 (0) | 1 (5) | – |
| Coniochaeta mutabilis | 1 (3) | 1 (6) | 0 (0) | – |
| Curvularia species | 1 (3) | 1 (6) | 0 (0) | – |
| Exophiala species | 1 (3) | 0 (0) | 1 (5) | – |
| Exserohilum species | 1 (3) | 1 (6) | 0 (0) | – |
| Malbranchea species | 1 (3) | 1 (6) | 0 (0) | – |
| Rhodotorula mucilaginosa | 1 (3) | 0 (0) | 1 (5) | – |
| Co-infection with other organisms | .98 | |||
| Coagulase-negative staphylococcus a | 6 (16) | 2 (13) | 4 (19) | |
| Micrococcus spp. a | 1 (3) | 1 (6) | 0 (0) |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
