Impairment of Lacrimal Secretion in the Unaffected Fellow Eye of Patients with Recurrent Unilateral Herpetic Keratitis

Emerging drugs for the treatment of herpetic keratitis

INTRODUCTION

Herpes simplex keratitis stands as a prominent factor contributing to infectious blindness among developed nations. On a global scale, over 60% of the population tests positive for herpes simplex virus type-1 (HSV-1). Despite these statistics, there is currently no vaccine available for the virus. Moreover, the conventional nucleoside drugs prescribed to patients are proving ineffective in addressing issues related to drug resistance, recurrence, latency, and the escalating risk of vision loss. Hence, it is imperative to continually explore all potential avenues to restrict the virus. This review article centers on the present treatment methods for HSV-1 keratitis (HSK), highlighting the ongoing clinical trials. It delves into the emerging drugs, their mode-of-action and future therapeutics.

AREAS COVERED

The review focuses on the significance of a variety of small molecules targeting HSV-1 lifecycle at multiple steps. Peer-reviewed articles and abstracts were searched in MEDLINE, PubMed, Embase, and clinical trial websites.

EXPERT OPINION

The exploration of small molecules that target specific pathways within the herpes lifecycle holds the potential for substantial impact on the antiviral pharmaceutical market. Simultaneously, the pursuit of disease-specific biomarkers has the capacity to usher in a transformative era in diagnostics within the field.

Structural and functional changes of binocular corneal innervation and ocular surface function after unilateral SMILE and tPRK

AIMS

To evaluate the bilateral changes in the sub-basal nerve plexus of the cornea and ocular surface function after unilateral small incision lenticule extraction (SMILE) and transepithelial photorefractive keratectomy (tPRK) procedures.

METHODS

34 patients were enrolled in the study and underwent unilateral SMILE (21 of 34 patients) or unilateral tPRK (13 of 34 patients). Complete ophthalmic examinations, tear film function tests and Cochet-Bonnet esthesiometry were conducted to assess the effects of the surgeries on the corneal nerves and tear function. Morphological changes were assessed using in vivo confocal microscopy to evaluate the corneal sub-basal nerve plexus and dendritic cells. ELISA was used to measure the tear neuromediators. Clinical and morphological data at each follow-up point were compared with preoperative baseline values.

RESULTS

All patients who underwent unilateral SMILE or tPRK procedures exhibited bilateral corneal nerve degenerative changes, decreased corneal sensitivity, worsening of dry eye symptoms and changes in bilateral tear neuromediators. In the SMILE group, bilateral corneal sensitivity was positively correlated with corneal nerve fibre length and negatively correlated with dendritic cell area. The dry eye severity was negatively correlated with corneal sensitivity. Tear levels of substance P and nerve growth factor were positively correlated with mean dendritic cell area and dry eye severity, but negatively correlated with corneal sensitivity. In the tPRK group, bilateral corneal sensitivity was positively correlated with corneal nerve fibre density.

CONCLUSIONS

Unilateral refractive surgery may bilaterally affect the morphology and function of corneal nerves and ocular surface status postoperatively.

Herpes simplex virus, varicella-zoster virus and cytomegalovirus keratitis: Facts for the clinician

Keratitis due to Herpes simplex virus (HSK), Varicella-Zoster virus (VZK) and Cytomegalovirus remains a frequent source of concern for many ophthalmologists. They are a frequent cause of emergency consultations at eye care centers and carry the risk of permanent loss of visual acuity or visual quality and/or chronic neurotrophic keratitis, resulting in a significant decrease in the quality of life. HSK and VZK can affect the corneal epithelium, stroma, or endothelium or a combination of layers. In contrast, most cases of CMV keratitis present as isolated endothelitis (CMVE), a clinical entity that has been described within the last 2 decades. These three types of viral keratitis are characterized by a high frequency of recurrences and each new episode increases the risk of sequelae. Hence, ophthalmologists must adapt the treatment to the clinical presentation of each recurrent episode in order to mitigate the immediate consequences of viral replication and the immune response on corneal transparency. In patients with frequent recurrences, preventive long-term antiviral treatment is strongly recommended. However, in some rare cases, continuous exposure to antivirals may promote the emergence of resistant viral strains, which can be difficult to manage. In the future, the introduction of new antiviral drugs, with differing modes of action compared to current medical therapy, could be an alternative until a truly effective preventive solution, such as a vaccine, is available.

Chitosan-Covered Calcium Phosphate Particles Co-Loaded with Superoxide Dismutase 1 and ACE Inhibitor: Development, Characterization and Effect on Intraocular Pressure

Improvement of the efficiency of drug penetration into the eye tissues is still an actual problem in ophthalmology. One of the most promising solutions is drug encapsulation in carriers capable of overcoming the cornea/sclera tissue barrier. Formulations on the base of antioxidant enzyme, superoxide dismutase 1 (SOD1), and an inhibitor of angiotensin-converting enzyme, enalaprilat, were prepared by simultaneous inclusion of both drugs into calcium phosphate (CaP) particles in situ with subsequent covering of the particles with 5 kDa chitosan. The formulations obtained were characterized by dynamic light scattering and scanning electron microscopy. Hybrid CaP-chitosan particles co-loaded with SOD1 and enalaprilat had a mean hydrodynamic diameter of 120-160 nm and ζ-potential +20 ± 1 mV. The percentage of the inclusion of SOD1 and enalaprilat in hybrid particles was 30% and 56%, respectively. The ability of SOD1 and enalaprilat to reduce intraocular pressure (IOP) was examined in vivo in normotensive Chinchilla rabbits. It was shown that topical instillations of SOD1/enalaprilat co-loaded hybrid particles were much more effective in decreasing IOP compared to free enzyme or free enalaprilat and even to the same particles that contained a single drug. Thus, the proposed formulations demonstrate potential as prospective therapeutic agents for the treatment of glaucoma.

Unilateral Herpetik Keratitli Hastalarda Kuru Göz Parametrelerinin Değerlendirilmesi

Amaç: Çalışmamızın amacı tek taraflı herpes simpleks virüs (HSV) keratiti olan hastalarda etkilenen ve etkilenmeyen gözler arasındaki gözyaşı parametrelerinin özellikle meibomian bezlerinin durumunun değerlendirilmesidir. Yöntem: Kliniğimizde tek taraflı HSV endoteliti ve HSV stromal keratiti tanılarıyla tedavi uygulanmış ve 3 aydan uzun süredir sakin dönemde seyreden hastaların muayeneleri ve gözyaşı filmi menisküsü yüksekliği (GFMY), alanı (GFMA), non-invazif gözyaşı kırılma zamanı (NIGKZ), schirmer testi, meibomian bezleri ekspressibilite gradeleri, drop-out dereceleri ve mikroyapısının değerlendirilmesini içeren gözyaşı parametreleri retrospektif olarak değerlendirildi. Bulgular: Hastalarımızın yaş ortalaması 58,0 (55,25-72,25) yıldı. Medyan NIGKZ etkilenen gözde 6,85 (4,62-17,0) sn. ve etkilenmemiş gözde 15,85 (10,47-17,15) sn. idi. Gruplar arasındaki değişim istatistiksel olarak anlamlı olmasa da, etkilenen gözde NIGKZ değerlerinin belirgin şekilde daha düşük olduğu gözlendi. Schirmer test değerleri, GFMY ve GFMA, etkilenen ve etkilenmeyen gözler arasında benzerdi. Etkilenen ve etkilenmeyen gözlerin meibomian bezi değerlendirmeleri, meibomian ekspresyonu ve bırakma dereceleri benzer dağılım gösterdi. Sonuç: Her iki gözde meibom bezlerinin hem morfolojik hem de mikroyapısal özelliklerinde benzer etkiler gözlemledik. Bu durum bize her iki gözde gelişen kuru göz hastalığının sadece nörosensoriyel anomalilerden değil meibomian bezlerdeki değişikliklerden de kaynaklanabileceğini düşündürmektedir.

Tear instability in the fellow eye of unilateral nasolacrimal obstruction and resolution with dacryocystorhinostomy

PURPOSE

To determine the effect of unilateral primary acquired nasolacrimal obstruction (PANDO) on ocular surface parameters in PANDOeyes and fellow eyes and changes in these parameters after dacryocystorhinostomy.

METHODS

Tear osmolarity, tear break-up time (TBUT), Schirmer's test, Meibomian gland score, and Lissamine Green staining of PANDO eyes and fellow eyes were measured preoperatively and postoperatively at Day 15, 1 month, and 3 months. Lacrimal irrigation and epiphora symptomatology were evaluated at all follow-up visits, and patients who did not meet surgical success criteria were excluded from the study.

RESULTS

Twenty-nine patients who underwent successful dacryocystorhinostomy surgery were included in the study. Preoperative and postoperative Day 15 Schirmer (p = .019, p = .001) and TBUT (p = .039, p = .043) were significantly lower in the fellow eye compared to PANDO eyes. The differences observed between PANDO eyes and fellow eyes in all other parameters were not significant (p > .05). Preoperatively PANDO eye parameters were normal, whereas TBUT (7.59 ± 5.39 s) and tear osmolarity (308.59 ± 17.32 mOsm/L) values of the fellow eye may be indicative of tear film instability. TBUT and tear osmolarity of the fellow eye showed significant improvement 3 months postoperatively compared to preoperative values (p = .010; p = .027 respectively).

CONCLUSION

Schirmer and TBUT values of the fellow eye were significantly lower than PANDO eyes preoperatively, one month after surgery there was no significant difference. TBUT and tear osmolarity of the fellow eyes may be indicative of tear instability preoperatively with improvement 3 months after dacryocystorhinostomy.

Reduced tear break-up time in the fellow eye of patients with unilateral primary acquired nasolacrimal duct obstruction

PURPOSE

To measure tear osmolarity, Schirmer I test and tear break-up time (TBUT) values in the obstructed and non-obstructed fellow eye of unilateral primary acquired nasolacrimal duct obstruction (PANDO) patients and compare them with healthy controls.

METHODS

In this prospective noninterventional study, the tear osmolarity, Schirmer I test, and TBUT values from unilateral PANDO eyes, fellow eyes, and control eyes of all subjects were measured.

RESULTS

The study included 114 eyes of 30 PANDO patients as well as 27 healthy controls. There was a significant difference between TBUT and Schirmer values of fellow eyes and PANDO eyes (p = 0,035; p = 0,001). There was no significant difference in any of the ocular surface parameters between PANDO eyes and control eyes (p > 0.05). When fellow eyes were compared to control eyes, there was a significant difference in TBUT (p = 0.046).

CONCLUSIONS

Decreased TBUT was exhibited by the fellow eye of unilateral PANDO patients, compared to the PANDO side and controls. Compensatory changes in PANDO eyes due to a decrease in the tear secretion reflex may lead to tear dysfunction of the fellow eye. Clinicians should assess tear stability in the fellow eye of PANDO patients as this could be leading to added symptomatic complaints.

Acyclovir-Resistant Herpes Simplex Virus 1 Keratitis: A Concerning and Emerging Clinical Challenge

PURPOSE

To describe the clinical and virological profiles of patients with herpes simplex keratitis (HSK) caused by acyclovir-resistant (ACV^R) strains of herpes simplex virus 1 (HSV-1).

DESIGN

Multicenter retrospective case series.

METHODS

HSV-1 resistance to ACV was confirmed using sequencing of genes encoding HSV-1 thymidine kinase (TK) and DNA polymerase (DNA pol). Data were collected on the number of HSK episodes before and after the diagnosis of resistance, ocular findings including the type of HSK, immune status of patients, antiviral treatments, and HSV-1 genotypic resistance profiles.

RESULTS

This study evaluated 18 HSK patients (13 male and 5 female, aged 66.8 ± 4.7 years) with ACV^R HSV-1-positive ocular samples. Genotypic resistance testing was performed because of frequent recurrences despite adequate antiviral prophylaxis (AVP) (n = 13, 72%), or poor response to suppressive antiviral therapy (n = 5, 28%). Resistance mutations were found in the TK (n = 15, 83%) or in the DNA pol gene (n = 3, 17%). Prior to the diagnosis of resistance, the duration of disease was 29.8 ± 20.4 years, with more than 10 HSK recurrences in 15 patients (83%). The number of recurrences between the first episode and the diagnosis of resistance was significantly lower in immunocompromised patients (n = 6, 33%) than in immunocompetent patients (n = 12; 67%) (11.5 ± 4.9 vs 16.4 ± 1.9, P = .05).

CONCLUSION

HSV-1 resistance to ACV must be suspected in HSK patients with recurrences despite AVP and/or in cases that respond poorly to a suppressive antiviral regimen. Immunocompromised patients and/or those with longstanding disease may be particularly at risk for developing resistance.

The Correlation between Matrix Metalloproteinase-9 Point-of-Care Immunoassay, Tear Film Osmolarity, and Ocular Surface Parameters

Background. Dry eye disease is a multifactorial disease that is difficult to diagnose due to multiple causative factors. The study aimed to evaluate the correlations between tear film matrix metalloproteinase-9 (MMP-9), tear film osmolarity, and ocular surface parameters in patients with dry eyes. Methods. We performed a retrospective chart review for patients diagnosed with dry eye and investigated if associations existed amongst noninvasive tear breakup time (NIBUT); corneal staining scores; and MMP-9 grade, tear film osmolarity, and Schirmer’s test I results. Results. Twenty-four eyes of 24 patients were enrolled in the current study. The grade of MMP-9 (0–4) was positively correlated with tear film osmolarity ( $p=0.027$ ). However, neither qualitative (positive or negative) nor quantitative (grade 0–4) measurements of MMP-9 correlated with any other ocular surface parameters. The osmolarity in the positive corneal staining group was significantly higher than that in the negative group (321.6 ± 19.261 and 299.89 ± 16.213, respectively; $p=0.018$ ). None of the other ocular surface parameters were correlated with tear film osmolarity. Conclusion. Tear film MMP-9 may be an indicator for tear film osmolarity, or vice-versa. Moreover, osmolarity may have a correlation with corneal staining in patients with dry eye. Tear film MMP-9 and osmolarity tests can be helpful and convenient evaluation tools for identifying inflammation in dry eye disease in clinical practice.

The Role of Neuropeptides in Pathogenesis of Dry Dye

Neuropeptides are known as important mediators between the nervous and immune systems. Recently, the role of the corneal nerve in the pathogenesis of various ocular surface diseases, including dry eye disease, has been highlighted. Neuropeptides are thought to be important factors in the pathogenesis of dry eye disease, as suggested by the well-known role between the nervous and immune systems, and several recently published studies have elucidated the previously unknown pathogenic mechanisms involved in the role of the neuropeptides secreted from the corneal nerves in dry eye disease. Here, we reviewed the emerging concept of neurogenic inflammation as one of the pathogenic mechanisms of dry eye disease, the recent results of related studies, and the direction of future research.

Altered Corneal Innervation and Ocular Surface Homeostasis in FHV-1-Exposed Cats: A Preliminary Study Suggesting Metaherpetic Disease

Metaherpetic disease is recognized in humans affected by herpes simplex virus-1 but is not reported in cats affected by feline herpesvirus-1 (FHV-1) despite the high prevalence of herpetic disease in this species and strong similarities in viral biology between alphaherpesviruses of humans and cats. This preliminary work evaluated cats naïve to FHV-1 (n = 9 cats, 18 eyes; control population) and cats naturally exposed to FHV-1 (n = 4 cats, 7 eyes), as confirmed by serologic testing and review of medical records. Antemortem assessment included clinical scoring, blink rate, corneal aesthesiometry, tear film breakup time (TFBUT), and Schirmer tear test-1 (STT-1) with or without the nasolacrimal reflex. Post-mortem assessment involved confocal microscopy of the corneas and evaluation of corneal nerves with ImageJ. Groups were compared with Student's t-tests and results are presented as mean ± standard deviation. Compared to control, herpetic cats had significantly higher (P ≤ 0.010) clinical scores (0.2 ± 0.4 vs. 4.6 ± 2.8) and response to nasolacrimal stimulation (7.8 ± 10.8% vs. 104.8 ± 151.1%), significantly lower (P < 0.001) corneal sensitivity (2.9 ± 0.6 cm vs. 1.4 ± 0.9 cm), STT-1 (20.8 ± 2.6 mm/min vs. 10.6 ± 6.0 mm/min), TFBUT (12.1 ± 2.0 s vs. 7.1 ± 2.9 s), and non-significantly lower blink rate (3.0 ± 1.5 blinks/min vs. 2.7 ± 0.5 blinks/min; P = 0.751). All parameters evaluated for corneal nerves (e.g., nerve fiber length, branching, occupancy) were notably but not significantly lower in herpetic vs. control cats (P ≥ 0.268). In sum, cats exposed to FHV-1 had signs suggestive of corneal hypoesthesia and quantitative/qualitative tear film deficiencies when compared to cats naïve to the virus. It is possible these are signs of metaherpetic disease as reported in other species.

Clinical features of cats with aqueous tear deficiency: a retrospective case series of 10 patients (17 eyes)

OBJECTIVES

The aim of this study was to describe the clinical findings, diagnostic test results and response to therapy of cats with Schirmer tear test 1 (STT-1) values below the reference interval.

METHODS

The medical records of three institutions were searched for cats with ocular surface disease and STT-1 values <9 mm/min, confirmed at two or more separate visits.

RESULTS

Ten cats (17 eyes) were included. The mean ± SD (range) age and STT-1 values in affected eye(s) were 6.1 ± 5.7 (0.2-16) years and 2.4 ± 3.1 (0-8) mm/min, respectively. Concurrent ocular surface disease was bilateral in 5/10 cats. Clinical signs included conjunctivitis (14/17 eyes), corneal ulceration (6/17 eyes), non-ulcerative keratitis (4/17 eyes), symblepharon (4/17 eyes), eosinophilic keratitis (3/17 eyes), corneal sequestrum (3/17 eyes), corneal fibrosis (2/17 eyes) and meibomitis (2/17 eyes). Management included: topically applied lacrimomimetics, antiviral drugs, corticosteroids or immunomodulatory drugs; orally administered famciclovir; or surgical procedures, in various combinations. Response to therapy (defined as an increase in STT-1 value of ⩾5 mm/min) was transient (seen at a single reassessment) in 65% of eyes and sustained (seen at ⩾2 consecutive reassessments) in 18% of eyes.

CONCLUSIONS AND RELEVANCE

Clinical features seen in cats with low STT-1 values are described, although the association between aqueous deficiency and the reported ocular changes is unknown at this time. We encourage clinicians to assess the tear film in cats with ocular surface disease, and initiate therapy with lacrimomimetics if STT-1 values are repeatedly below normal. Such information will further define aqueous tear deficiency in cats, providing a better understanding of disease prevalence, pathogenesis and treatment.

[Pathogenesis and epidemiology of neurotrophic keratopathy]

Neurotrophic keratopathy (NK) is a degenerative corneal disease that is based on an impairment of the corneal innervation. The damage to the sensory innervation, which is delivered through the 1st branch of the trigeminal nerve (ophthalmic nerve), can occur throughout the entire length of the nerve from the nucleus in the brainstem, e.g. caused by brain tumors, to the terminal nerve fibers in the cornea, caused for example by refractive corneal surgery (e. g. LASIK). Due to the loss of the sensory innervation, a reduced lacrimation and a reduction in the secretion of trophic factors occur. This in turn inhibits the regeneration potential of the corneal epithelium. In the most severe cases of the disease, the reduction or loss of lacrimation, together with the impaired regeneration potential of the epithelial cells, can lead to persistent epithelial defects, ulcers and corneal perforation. The NK has a prevalence of 5 or fewer individuals per 10,000 and is classified as a rare, i. e. orphan disease (ORPHA137596). A fundamental understanding of the pathogenesis and epidemiology of NK supports the early diagnosis and therefore the initiation of a specific treatment.

Pathogenesis of herpes simplex keratitis: The host cell response and ocular surface sequelae to infection and inflammation

Herpes simplex virus type 1 (HSV) keratitis is a leading cause of infectious blindness. Clinical disease occurs variably throughout the cornea from epithelium to endothelium and recurrent HSV stromal keratitis is associated with corneal scarring and neovascularization. HSV keratitis can be associated with ocular pain and subsequent neutrophic keratopathy. Host cell interactions with HSV trigger an inflammatory cascade responsible not only for clearance of virus but also for progressive corneal opacification due to inflammatory cell infiltrate, angiogenesis, and corneal nerve loss. Current antiviral therapies target viral replication to decrease disease duration, severity and recurrence, but there are limitations to these agents. Therapies directed towards viral entry into cells, protein synthesis, inflammatory cytokines and vascular endothelial growth factor pathways in animal models represent promising new approaches to the treatment of recurrent HSV keratitis.

Management of herpes simplex virus epithelial keratitis

PURPOSE OF REVIEW

To review recent advancements in the management of herpes simplex virus (HSV) epithelial keratitis.

RECENT FINDINGS

Trifluridine eye drop, acyclovir (ACV) ointment, ganciclovir gel, and oral ACV are still the main therapeutic agents. Cryopreserved amniotic membrane has been recently used as an adjuvant treatment. Resistance to ACV has become a concerning issue. The animal models of HSV vaccine are able to reduce HSV keratitis. New antivirals are under development.

SUMMARY

Current cases of HSV epithelial keratitis are manageable with available medications, but new advancements are required to decrease disease burden in the future. HSV vaccine can be revolutionary.

Central Connections of the Lacrimal Functional Unit

PURPOSE

To study the contribution of each eye to the reflex tear response, after unilateral and bilateral topical anesthesia.

METHOD

A closed-eye, modified Schirmer test was performed bilaterally in 8 normal subjects, in a controlled environment chamber set to 23°C, 45% relative humidity, and 0.08 m/s airflow. Eye drops were instilled into each eye 10 minutes before the Schirmer test. Experiments were as follows: 1) bilateral saline (control), 2) unilateral anesthesia (ipsilateral anesthetic; contralateral saline), and 3) bilateral anesthesia.

RESULTS

There was no difference in between-eye wetting lengths in the saline control eyes (P = 0.394) or the bilaterally anesthetized eyes (P = 0.171). The wetting length was reduced in both eyes after bilateral anesthesia compared with saline controls (P = 0.001; P ≤ 0.0005). After unilateral anesthesia, the wetting length was reduced in the anesthetized eye compared with its saline control by 51.4% (P ≤ 0.0005) and compared with its fellow, unanesthetized eye (P = 0.005). The fellow eye value was also reduced compared with its saline control (P = 0.06).

CONCLUSIONS

The wetting length was reduced by topical anesthesia, when instilled bilaterally and ipsilaterally. The latter response implies an ipsilateral, reflex sensory drive to lacrimal secretion. In the unanesthetized fellow eye, the reduction compared with its saline control was not quite significant. This implies a relative lack of central, sensory, reflex cross-innervation, although the possibility cannot entirely be ruled out. These results are relevant to the possibility of reflex lacrimal compensation from a normal fellow eye, in cases of unilateral corneal anesthesia.

Clinical impact of inflammation in dry eye disease: proceedings of the ODISSEY group meeting

Dry eye disease (DED) is a common, multifactorial ocular condition with major impact on vision and quality of life. It is now well recognized that the pathophysiology of chronic DED can include a cycle of inflammation involving both innate and adaptive immune responses. Recently, in vitro/in vivo models have been used to obtain a better understanding of DED‐related inflammatory processes at molecular/cellular levels although they do not truly reproduce the complex and chronic hallmarks of human DED. In clinical DED research, advanced techniques such as impression cytology, conjunctival biopsy, in vivo confocal microscopy and multiplex tear analyses have allowed an improved assessment of inflammation in DED patients. This was supported by the identification of reliable inflammatory markers including matrix metalloproteinase‐9, human leucocyte antigen‐DR or intercellular adhesion molecule‐1 in tears and impression cytology samples. One of the current therapeutic strategies focuses on breaking the inflammatory cycle perpetuating the ocular surface disease, and preclinical/clinical research has led to the development of promising anti‐inflammatory compounds. For instance, cyclosporine, already approved in the United States, has recently been authorized in Europe to treat DED associated with severe keratitis. In addition, other agents such as corticosteroids, doxycycline and essential fatty acids, through their anti‐inflammatory properties, show encouraging results. We now have a clearer understanding of the inflammatory processes involved in DED, and there is hope that the still emerging preclinical/clinical findings will be translated into new and highly effective therapies for patients in the near future.

Tear Osmolarity and Correlation With Ocular Surface Parameters in Patients With Dry Eye

PURPOSE

To analyze the distribution of tear film osmolarity in patients with dry eye and its association with other ocular surface parameters.

METHODS

Tear osmolarity and other quantitative dry eye parameters were obtained from patients with 1) clinically significant dry eye (significant symptoms and ocular surface staining, n = 131), 2) symptoms-only dry eye (significant symptoms but no significant ocular surface staining, n = 52), and 3) controls (no significant symptoms or staining, n = 42).

RESULTS

Tear osmolarity varied significantly across groups (P = 0.01), with patients with clinically significant dry eye having the highest tear osmolarity (312.0 ± 16.9 mOsm/L), control patients having the lowest tear osmolarity (305.6 ± 9.7 mOsm/L), and patients with symptoms-only dry eye falling in between (307.4 ± 5.6 mOsm/L). Patients with clinically significant dry eye also tended to have a greater intereye difference in osmolarity (12.0 ± 13.4) than did the individuals with symptoms-only dry eye (9.1 ± 12.4) and controls (9.0 ± 7.4) (P = 0.06). In multivariable regression models, higher tear osmolarity was associated with higher Ocular Surface Disease Index, discomfort subscore (P = 0.02), and higher corneal and conjunctival staining scores (P < 0.01 for both). Worse eye tear osmolarity was not correlated with the corresponding tear film breakup time or Schirmer test (P > 0.05 for both).

CONCLUSIONS

Individuals with symptomatic dry eye that is not yet clinically significant seem to have higher and more variable osmolarity measurements than controls, potentially indicating that changes in osmolarity precede clinical findings.

Feline dry eye syndrome of presumed neurogenic origin: a case report

Case summary

A 14-year-old female spayed Abyssinian cat, which about 1 year previously underwent thoracic limb amputation, radiotherapy and chemotherapy for an incompletely excised vaccine-related fibrosarcoma, was presented for evaluation of corneal opacity in the left eye (OS). The ocular surface of both eyes (OU) had a lackluster appearance and there was a stromal corneal ulcer OS. Results of corneal aesthesiometry, Schirmer tear test-1 (STT-1) and tear film breakup time revealed corneal hypoesthesia, and quantitative and qualitative tear film deficiency OU. Noxious olfactory stimulation caused increased lacrimation relative to standard STT-1 values suggesting an intact nasolacrimal reflex. Various lacrimostimulants were administered in succession; namely, 1% pilocarpine administered topically (15 days) or orally (19 days), and topically applied 0.03% tacrolimus (47 days). Pilocarpine, especially when given orally, was associated with notable increases in STT-1 values, but corneal ulceration remained/recurred regardless of administration route, and oral pilocarpine resulted in gastrointestinal upset. Tacrolimus was not effective. After 93 days, the cat became weak and lame and a low thyroxine concentration was detected in serum. The cat was euthanized and a necropsy performed. Both lacrimal glands were histologically normal, but chronic neutrophilic keratitis and reduced conjunctival goblet cell density were noted OU.

Relevance and novel information

The final diagnosis was dry eye syndrome (DES) of presumed neurogenic origin, associated with corneal hypoesthesia. This report reinforces the importance of conducting tearfilm testing in cats with ocular surface disease, as clinical signs of DES were different from those described in dogs.

Bilateral tear film alterations in patients with unilateral quiescent herpes simplex keratitis

PURPOSE

To evaluate bilateral tear function and corneal sensitivity in patients with unilateral quiescent herpes simplex keratitis (HSK) and determine the correlation between corneal sensitivity and tear secretion in both eyes.

METHODS

Thirty-five patients diagnosed with unilateral quiescent HSK and 35 heathy controls were included in this study. Bilateral tear osmolarity, Schirmer's test, the tear break-up time (TBUT) and corneal sensitivity were measured in all participants.

RESULTS

In the HSK group, both eyes demonstrated a significant increase in tear osmolarity, and a decrease in Schirmer's test and the TBUT compared with healthy controls (All p < 0.001). The bilateral tear osmolarity and Schirmer's test were similar, but the TBUT (4.9 ± 2.1 versus 7.4 ± 2.0 second; p < 0.001) and corneal sensitivity (35.1 ± 1.9 versus 54.3 ± 0.8 mm; p < 0.001) were significantly lower in the affected eyes. The bilateral tear osmolarity, Schirmer's test and the TBUT were significantly correlated with corneal sensitivity of the affected eye (All p < 0.001). When corneal sensitivity of the unaffected eye was treated as a control variable, tear osmolarity (R = -0.626, p < 0.001), Schirmer's test (R = 0.739, p < 0.001) and the TBUT (R = 0.691, p < 0.001) of the unaffected eyes were still significantly correlated with the corneal sensitivity of the affected eyes.

CONCLUSIONS

Unilateral quiescent HSK causes bilateral tear impairment, which depends on the loss of corneal sensitivity in the affected eye. In the affected eye with severe corneal sensitivity loss, bilateral dry eye occurred.

Do Unilateral Herpetic Stromal Keratitis and Neurotrophic Ulcers Cause Bilateral Dry Eye?

PURPOSE

To evaluate and compare the ocular surface condition in herpetic interstitial stromal keratitis and neurotrophic ulcer groups and their normal fellow eyes.

METHODS

In this observational, cross-sectional case-control study, 85 consecutive patients were included, including 56 cases of treated herpetic interstitial keratitis and 29 patients with neurotrophic ulcers. Fifty-six age- and sex-matched participants were also recruited from a normal population as the control group. We evaluated and scored the subjective and objective measures of dry eye for both eyes of all patients. Then, we compared the score of the groups with one another and also with the control group. The main outcome measures were the discomfort level, visual symptoms of dry eye, conjunctival injection, conjunctival staining, corneal staining, corneal tear signs of dry eye, meibomian gland dysfunction, tear break-up time, Schirmer test score with anesthesia, and tear osmolarity.

RESULTS

The normal fellow eye of the herpetic keratitis group had significantly higher discomfort levels (1.4 ± 0.9 vs. 1.3 ± 0.5, P = 0.003), visual symptoms (1.7 ± 0.8 vs. 1.3 ± 0.7, P = 0.002), tear break-up time (8.3 ± 3.2 vs. 12.1 ± 3.3 seconds, P = 0.003), Schirmer test scores (9.2 ± 3.9 vs. 12.9 ± 3 mm, P = 0.04), and tear osmolarity (9.2 ± 3.9 vs. 12.9 ± 3 mm, P = 0.003) in comparison with normal controls. The normal fellow eyes of the neurotrophic ulcer group had significantly worse values for discomfort level (1.9 ± 0.9 vs. 1.3 ± 0.5, P < 0.001), tear break-up time (7.9 ± 4 vs. 12.1 ± 3.3, P = 0.004), Schirmer test score (8.1 ± 3.9 vs. 12.9 ± 3, P = 0.005), and tear osmolarity (295 ± 9.2 vs. 292.7 ± 5.9, P = 0.02) compared with normal controls.

CONCLUSIONS

Both eyes of patients with neurotrophic ulcer and interstitial herpetic keratitis have a significantly poorer ocular surface condition compared with that of normal controls.

Tear film osmolarity and dry eye disease: a review of the literature

Objective

To evaluate the evidence in the peer-reviewed literature regarding the use of tear osmolarity as a physiological marker to diagnose, grade severity, and track therapeutic response in dry eye disease (DED). In addition, to review the evidence for the role of tear osmolarity in the pathophysiology of DED and ocular surface disease.

Methods

A literature review of all publications after the year 2000, which included the keywords “tear osmolarity”, was conducted. Relevant articles were graded according to quality of evidence and research, using the University of Michigan Practice Guideline and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) rating systems. Articles were further categorized by the nature of any reported financial support and by the overall impression they provided related to tear osmolarity.

Results

A total of 164 articles were identified as relevant to the search criteria, although some were editorials, and some were written in a foreign language. Of the total, it was possible to grade 159, and an overall impression was generated for 163. A positive impression of tear osmolarity in DED diagnosis was evident in 72% (117/163) of all articles, with a neutral impression in a further 21% (35/163); 7% had a negative impression. The percentage of positive impressions appeared independent of the quality of research; 73% (38/52) of articles graded high/moderate quality supported the use of tear film osmolarity measurement in DED diagnosis. Impressions were also independent of the source of financial support, with 72% (75/104) of independent studies positive.

Conclusion

The literature broadly supports the use of tear film osmolarity as an objective numerical measure for diagnosing, grading severity, and managing treatment of DED.

Diffusion tensor magnetic resonance imaging of trigeminal nerves in relapsing herpetic keratouveitis

Background

Corneal hypoesthesia is the landmark of HSV and VZV keratitis and can lead to neurotrophic keratitis. Diffusion tensor imaging (DTI) is a new magnetic resonance imaging (MRI) derived technique, which offers possibilities to study axonal architecture. We aimed at assessing the potential impact of recurrent HSV or VZV-related keratitis on the axonal architecture of trigeminal nerves using DTI.

Design

Prospective non-interventional study.

Participants

Twelve patients and 24 controls.

Methods

DTI using MRI of the trigeminal fibers and corneal esthesiometry using the Cochet-Bonnet esthesiometer were acquired for patients affected by unilateral and recurrent HSV or VZV-related keratitis (3 months after the last corneal inflammatory event), and control subjects with no history of ocular or neuronal disease affecting the trigeminal pathways.

Main Outcome Measures

Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were compared between the 2 eyes of both patients and controls, and correlated with corneal esthesiometry.

Results

FA was lower in the trigeminal fibers ipsilateral to the affected eye compared to the non-affected side (0.39±0.02 versus 0.46±0.04, P=0.03). This difference was more important than the intra-individual variability observed in controls. Concomitantly, the asymmetry in ADC results was significantly correlated with the loss of corneal sensitivity in the affected eye.

Conclusions

Corneal hypoesthesia related to HSV and VZV keratitis is associated with persistent modifications in the architecture and functionality of the trigeminal fibers. These results add further explanation to the pathogenesis of HSV and VZV-induced neurotrophic keratitis, which may occur despite an apparent quiescence of the disease.

Diagnosing the severity of dry eye: a clear and practical algorithm

Dry eye disease (DED) is a distressing ocular condition. Due to its multifactorial nature, clinical and biological signs of DED can be inconsistent and sometimes discordant with symptomatology. Consequently, no gold-standard model for determining DED severity exists. This can impact treatment decisions and complicate evaluation of disease progression, particularly within the stringent context of clinical trials. The multinational ODISSEY European Consensus Group is comprised of ophthalmologists who contend with ocular surface disease issues on a daily basis. This group convened to establish a clear and practical algorithm for evaluation and diagnosis of severe DED. Using a consensus-based approach, they assessed 14 commonly used DED severity criteria. The panel agreed that following confirmed DED diagnosis, just two criteria, symptom-based assessment and corneal fluorescein staining were sufficient to diagnose the presence of severe DED in the majority of patients. In the event of discordance between signs and symptoms, further evaluation using additional determinant criteria was recommended. This report presents the ODISSEY European Consensus Group recommended algorithm for DED evaluation, which facilitates diagnosis of severe disease even in the event of discordance between signs and symptoms. It is intended that this algorithm will be useful in a clinical and developmental setting.

Role of hyperosmolarity in the pathogenesis and management of dry eye disease: proceedings of the OCEAN group meeting

Dry eye disease (DED), a multifactorial disease of the tears and ocular surface, is common and has a significant impact on quality of life. Reduced aqueous tear flow and/or increased evaporation of the aqueous tear phase leads to tear hyperosmolarity, a key step in the vicious circle of DED pathology. Tear hyperosmolarity gives rise to morphological changes such as apoptosis of cells of the conjunctiva and cornea, and triggers inflammatory cascades that contribute to further cell death, including loss of mucin-producing goblet cells. This exacerbates tear film instability and drives the cycle of events that perpetuate the condition. Traditional approaches to counteracting tear hyperosmolarity in DED include use of hypotonic tear substitutes, which have relatively short persistence in the eye. More recent attempts to counteract tear hyperosmolarity in DED have included osmoprotectants, small organic molecules that are used in many cell types throughout the natural world to restore cell volume and stabilize protein function, allowing adaptation to hyperosmolarity. There is now an expanding pool of clinical data on the efficacy of DED therapies that include osmoprotectants such as erythritol, taurine, trehalose and L-carnitine. Osmoprotectants in DED may directly protect cells against hyperosmolarity and thereby promote exit from the vicious circle of DED physiopathology.

From pathogenic considerations to a simplified decision-making schema in dry eye disease

The modern definition of Dry Eye Disease (DED) combines objective findings, subjective symptoms and mechanistic considerations, among which hyperosmolarity and inflammation play a key role. Historically, DED were classified as due to either insufficient production or impaired stability of tears. There is now evidence that such a dichotomous classification does not fit with the reality of clinical practice, since any abnormality of the ocular surface can trigger disequilibrium in all the other components of tear dynamics. This results in a vicious circle with as many ways to enter as there are causes of destabilization of the ocular surface. Eventually, the patient develops a self-sustaining, and finally severe, DED. Based on these data, we propose a simplified decision-making schema with the goal of assisting ophthalmologists in daily practice in choosing the first line treatment for dry eye disease, and then, if necessary, adapting treatment for the long-term.