Purpose
This study investigated the clinical manifestation and risk factors associated with remission in filamentary keratitis.
Design
Retrospective, interventional, comparative case series.
Methods
We retrospectively reviewed the medical records of 116 patients with filamentary keratitis diagnosed and treated between January 2012 and December 2018. We investigated the 5 causative factors including brain lesion, dry eye syndrome, autoimmune disease, ocular surgery or injury, and other conditions; treatment methods and duration; and remission status, and analyzed the risk factors associated with remission.
Results
The mean age of the patients was 56.9 ± 19.1 years and the mean follow-up duration was 14.9 ± 22.8 months. The most common underlying condition associated with filamentary keratitis was identified as a brain lesion (36.2%), followed by dry eye syndrome (30.2%) and autoimmune disease (24.1%). A comparison of remission rates among the causative factors revealed that cases associated with brain lesions had significantly lower remission rates (33.3%) than those associated with other causative factors (>60%) ( P = .001). After adjustment for sex, age, diabetes mellitus, and hypertension, the treatment failure rate in patients affected by brain lesions was 6.602-fold higher than that associated without brain lesion ( P = .001). The treatment method–dependent differences in the remission rate were observed in brain lesion and dry eye syndrome ( P = .041 and P = .005, respectively).
Conclusions
The most common condition leading to filamentary keratitis was a brain lesion, followed by dry eye syndrome and autoimmune disease. The treatment failure rate was statistically significantly low only in patients with filamentary keratitis associated with brain lesions.
Highlights
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Filamentary keratitis is associated with various ocular conditions, including brain lesion, dry eye syndrome, and autoimmune diseases.
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Among the 5 categorized causative factors of filamentary keratitis (brain lesion, dry eye syndrome, autoimmune disease, ocular surgery or injury, and others), the most common cause was brain lesion.
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The remission rate of filamentary keratitis is the lowest in patients with brain lesion, with statistical significance ( P = .001).
Filamentary keratitis is an umbrella term for conditions in which filaments are attached to the cornea and, more rarely, conjunctival surface. Filaments are composed of degenerated epithelial cells and mucus, and they cause pain on eye movement, photophobia, watery eye, foreign body sensation, and blepharospasm. Filamentary keratitis may occur at any time on the ocular surface under an abnormal tear film condition, and known high-risk groups are patients with dry eye syndrome, autoimmune disease, exposure keratopathy, ocular surgery or injury, , prolonged eyelid closure, , superior limbic keratopathy, and brainstem lesions. , Filamentary keratitis is a chronic and recurrent disease, and successful treatment that avoids recurrence can be challenging. Conventional treatments include mechanical removal of filaments followed by the correction of underlying ocular diseases using preservative-free artificial tear supplements and punctal occlusion; reduction of inflammation using anti-inflammatory agents including steroids and cyclosporine; reduction of the viscosity of the mucinous component of the tear film using N-acetylcysteine eye drops; and, for mechanical protection, therapeutic contact lens. ,
At present, only limited reports of histologic analyses or treatment methods of filamentary keratitis are available. No in-depth research has been conducted to date to investigate etiology-dependent remission rates and factors influencing remission. We have addressed this research gap by investigating in detail the clinical features of patients with filamentary keratitis and remission-related factors.
Methods
The retrospective, interventional, comparative case series were carried out following the tenets of the Declaration of Helsinki and was approved by the institutional review board of Ewha Womans University Mokdong Hospital (IRB No.: EUMC 2019-10-010) and registered at the Clinical Research Information Service (CRiS No.: KCT0004866).
Data Collection
We retrospectively reviewed the medical records of 116 outpatients and inpatients with filamentary keratitis diagnosed and treated between January 2012 and December 2018 at Ewha Womans University Mokdong Hospital.
In all patients, slit-lamp microscopy was used for diagnosis after staining the ocular surface with a fluorescein eye stain strip. In cases where a slit-lamp microscope could not be used, a hand-held slit lamp (SL-15, Kowa Ophthalmic & Medical Equipment, Nagoya, Aichi, Japan; SLM-6M, Chongqing Kanghua Ruiming S&T Co, Ltd, Chongqing, China) was used.
We investigated the patient characteristics (sex, age, underlying diseases, history of ophthalmic diseases), causative factors for filamentary keratitis, treatment methods and duration, and remission status. We divided the patients into 3 age groups (<30, 30-59, ≥60 years) and categorized the conditions leading to filamentary keratitis into 5 causative factors, namely, brain lesion, dry eye syndrome, autoimmune disease, ocular surgery or injury, and other ophthalmic conditions. Autoimmune disease included Sjögren syndrome and graft-vs-host disease, and dry eye syndrome included cases not associated with these autoimmune diseases. To focus on the factors associated with recurrence of filaments, we excluded filamentary keratitis occurrence in epidemic keratoconjunctivitis because most of the cases showed episodic filaments on the ocular surface during the disease course and they did not recur. Patients who visited our clinic fewer than 4 times were also excluded.
Treatment Methods and Definition of Remission
In all patients, treatment was preceded by the removal of filaments with cotton swabs or forceps after using topical anesthetics. The treatment methods were classified into 5 groups: (1) bandage soft contact lens; (2) 5% or 10% N-acetylcysteine drops; (3) autologous serum eye drops; (4) conservative care (eye drops) for each underlying disease; and (5) combination therapy. Remission was defined as the disappearance of filaments after removing the bandage soft contact lens for those treated with the bandage soft contact lens and after ceasing the application of 5% or 10% N-acetylcysteine or autologous serum eye drops for those treated with the application of those eye drops. Treatment failure was defined as persistence of filaments despite treatment.
Statistical Analysis
For statistical analysis, we used SPSS Statistics 25.0 (SPSS Inc, Chicago, Illinois, USA), and Fisher exact test and the χ 2 test were used for comparing remission status among causative factors, locations of brain lesions, and treatment methods. In the event of statistically significant differences in remission status, we calculated the odds ratio using the logistic regression model, and P < .05 was set as the threshold for a statistically significant difference.
Results
The patients’ demographics, causative factors, and laterality are listed in Table 1 . The mean age of the patients was 56.9 ± 19.1 years (range: 6-92 years), and the mean follow-up period was 14.9 ± 22.8 months (range, 0-83 months). Analysis of the patients across all age groups revealed brain lesions (n = 42) as the most common cause, followed by dry eye syndrome (n = 35) and autoimmune disease (n = 28).
| Clinical Characteristics | N (%) |
|---|---|
| Age (mean ± SD, years) | 56.9 ± 19.1 |
| Follow-up duration (mean ± SD, months) | 14.9 ± 22.8 |
| Sex | |
| Female | 69 (59.5) |
| Male | 47 (40.5) |
| DM | |
| Yes | 12 (10.3) |
| No | 104 (89.7) |
| HTN | |
| Yes | 27 (23.3) |
| No | 89 (76.7) |
| Causative factors and laterality | Both/Right/Left |
| Brain lesion (n = 42) | 20 (47.6)/5 (11.9)/17 (40.5) |
| Dry eye syndrome (n = 35) | 8 (22.9)/9 (25.7)/18 (51.4) |
| Autoimmune disease (n = 28) | 12 (42.9)/7 (25.0)/9 (32.1) |
| Ocular surgery or injury (n = 6) | 2 (33.3)/2 (33.3)/2 (33.3) |
| Others (n = 5) | 1 (20.0)/2 (40.0)/2 (40.0) |
Patients were divided into 3 age groups: <30 years (n = 8), 30-59 years (n = 54), and ≥60 years (n = 54) ( Figure ). In the young and mid-aged group (<60 years), brain lesion was the most common; on the other hand, in the old-aged group (≥60 years), dry eye syndrome was the most common.
We also examined the locations of filaments that were available in 103 cases, depending on the causative factor. In all patients with a history of ocular surgery or injury (n = 3), filaments were found at suture sites (100%). For all other causative factors, the most common location of filaments was the interpalpebral zone ( Table 2 ).
| Causative Factors | Patients a | IP | Inf | Sup | Multi | Sut |
|---|---|---|---|---|---|---|
| Brain lesion | 38 | 26 (68.4) | 1 (2.6) | 6 (15.8) | 5 (13.2) | 0 (0.0) |
| Dry eye syndrome | 32 | 15 (46.9) | 8 (25.0) | 3 (9.4) | 6 (18.8) | 0 (0.0) |
| Autoimmune disease | 25 | 14 (56.0) | 9 (36.0) | 0 (0.0) | 2 (8.0) | 0 (0.0) |
| Ocular surgery or injury | 3 | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) | 3 (100.0) |
| Others | 5 | 3 (60.0) | 2 (40.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
| Total | 103 | 58 (56.3) | 20 (19.4) | 9 (8.7) | 13 (12.6) | 3 (2.9) |
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