Clinical indicators of dry eye severity nursing outcome in intensive care unit*

Objective: to verify the extent of impairment of the clinical indicators of the nursing outcome Dry Eye Severity in patients admitted to the Intensive Care Unit. Method: cross-sectional, descriptive study developed with 206 patients. Based on the result listed, six indicators of the Classification of Nursing Results were evaluated with a questionnaire containing clinical variables and the Likert scale of the Classification of Nursing Results with constructed definitions, which varies from more impaired to non-impaired. The data were analyzed using descriptive and inferential statistics. Results: the decrease in lacrimal production and the presence of redness in the conjunctiva were more impaired. The other indicators were more frequent for the absence of impairment: incomplete eyelid closure 81% (167), excessive tearing 95.1%(196), excessive mucous secretion 78.7% (162) and decreased blinking mechanism 50.5% (104). The clinical characteristics of hospitalization for neurological disorders, invasive mechanical ventilation, chemosis, use of sedatives, vasoconstrictors, benzodiazepines, antibiotics and corticosteroids interfered in the impairment of the dry eye severity. Conclusion: the result indicators show that the clinical characteristics of patients in the intensive care unit interfere in the impairment and in the dry eyes severity. According to these results, the importance of assistance directed to the prevention of eye diseases is emphasized.


Introduction
Dry eye syndrome is defined as a multifactorial disease of the ocular surface characterized by loss of tear film homeostasis, with ocular symptoms, in which the instability and hyperosmolarity of the tear film, inflammation and damage of the ocular surface and neurosensory abnormalities have etiological significance (1) .
The most common risk factors for Dry Eye occurrence include: age over 60 years; female gender, especially those women receiving estrogen replacement therapy; wearing contact lenses; low humidity environment; systemic drugs (antihypertensives, diuretics, sedatives, neuromuscular blockers, benzodiazepines, anti-inflammatories, antihistamines, antibiotics, corticosteroids and vasoactive drugs) and autoimmune disorders (diabetes mellitus, sjögren syndrome, thyroid disease) (1)(2) . The diagnosis of ocular surface disease is based on the signs, symptoms and clinical history of the patient associated with some quantitative and qualitative tests (2) .

Dry Eye Workshop II (DEWS II) indicates that this
is a global problem, affecting more than 30 million people in the United States, and is one of the most frequent causes of demand for specialized eye care. In Asia and Europe, the prevalence of the syndrome, with and without symptoms, varies widely from 5% to 50% and its prevalence based only on signs is even more variable, reaching up to 75% in some populations (1) .
In Brazil, in the Intensive Care Unit (ICU), its occurrence becomes a concern. A previous cohort study indicates the presence of a global incidence of 53% of the outcome in patients hospitalized during the evaluated period (3) .
In these units, this problem becomes relevant, since patients admitted in this context are often in very critical health situations that increase the risk of developing ocular alterations. In addition, they are continuously exposed to environmental factors such as low temperature and humidity, which contribute to the occurrence of eye dryness and consequently Dry Eye (3) .
In this perspective, the adoption of a preventive approach and the implementation of eye care is very important for ICU patients; however, there is a prioritization of more urgent and complex care. The nursing team, responsible for comprehensive and systematized care, provides more time of assistance to these patients, by identifying risk factors and adopting preventive measures (4) .

This study is regulated by the Sistematização da
Assistência de Enfermagem -SAE (Systematization of Nursing Assistance), operated by the Nursing Process (NP) in five stages (historical, diagnostics, planning, implementation and evaluation of nursing) and guided by the NANDA International, Inc.(NANDA-I) classification systems (5) , Nursing Interventions Classification (NIC) (6) and Nursing Outcome Classification (NOC) (7) . It is based on the Nursing Diagnosis (ND) (00219) Risk of dry eyes of taxonomy of NANDA-I specified as "Susceptibility to eye discomfort or damage to the cornea and conjunctiva due to reduced amount or quality of tears to hydrate the eye, which can compromise health." (5) ; and, especially, in the Nursing Outcome (NO) (2110) Dry Eye Severity of the NOC taxonomy, defined as "severity of signs and symptoms of insufficient tears" (7)(8) .
The Nursing Outcome Dry Eye Severity offers to the nurses a complete set of data to guide decisions, establish goals and classify uniformly the assessment of the health status of patients and direct the provision of care (8) . The Likert-type scale scores correspond to each indicator; the measurement of the result establishes a baseline score and classify the result obtained after the intervention. This scale varies from a more impaired value (1) to a non-impaired one (5) (7) .
The NOC presents advantages such as reduced documentation time, better patient satisfaction and results, greater uniformity in the evaluation of the professional nurse and improved quality of care (9)(10) .  (12) .
The variables chosen as clinical characteristics were selected by the researchers based on the research that presented relationships between the elements of the phenomenon in their state-of-the-art (1)(2)(3)8) .
In order to avoid measurement biases, in the period prior to data collection, an eight hours training was carried out to two distinct teams: evaluators and  previously evaluated by observation of the researcher, records of medical records and use of specific materials already mentioned above.
After this intervention, the degree of impairment was evaluated by the NO Dry Eye Severity using an instrument with constitutive, operational definitions and operational magnitudes (8) in order to achieve greater accuracy in the evaluation and reduce the subjectivity of clinical judgment. It was used after prior authorization by the author of the instrument, as a tool for the analysis of the clinical indicators of choice for the study, as shown in Figure 1. The instrument of the NO Dry Eye Severity with the definitions constructed in a previous study (8) was submitted to content validation in two stages, the first by specialists and the second with a consensus group. indicator was considered when a score from 1 to 3

Decrease in tear production
(from severe to moderate impairment) was assigned, and not impaired when the indicators had a score of 4

Results
Of the 206 patients in the sample of this study, greater in the use of corticosteroids.

The occurrence of impairment of the indicator
Conjunctiva redness is 69% higher in the use of benzodiazepines and 62% higher in patients who use vasoconstrictors. The presence of impairment of the indicator Decrease in lacrimal production is 51% higher when antibiotics are used.

Discussion
Although Dry Eye is one of the most frequent ophthalmic conditions in the world, studies to evaluate its severity results in Intensive Care Unit need attention (8) .

Tears have lubricant and antimicrobial properties
that protect the ocular surface against dryness and eliminate particles and microorganisms. When a decrease in lacrimal production occurs, the person becomes vulnerable to external agents and prone to develop the dry eye (13) .
It is possible to measure this decrease from the Schirmer test, which is considered normal when the values are above 10mm/5min. A study carried out in ICU of a hospital in Turkey showed that the decrease in lacrimal production quantified by the Schirmer test of less than 10 mm/5 min was found in 70% of the sample and a score of less than 5 mm/5 min in 40% of patients (13) . In this study, we observed that ICU patients obtained the indicator severe Decrease in lacrimal production and moderately impaired (< 2mm and < 5 mm, respectively), since the frequencies were higher for scores 1 (23.3%) and 2 (27.2%).
The eyelid closure involves an active process of contraction of the orbicular muscle and inhibition of the upper eyelid lifting muscle. Incomplete eyelid closure is one of the main indicators with potential to trigger eye disorders, due to total or partial exposure of the eye surface and consequent excessive tear evaporation (14) .
In this study, if evaluated individually, it was found that the incomplete eyelid closure was absent (score  right eye and 24.3% in the left (increased involvement in 6.6% and 9.6%, respectively) (14) .
The use of IMV, according to the literature, may impair ocular homeostasis. There is a discussion about the use of this ventilatory device to cause an increase in intraocular pressure resulting in altered perfusion.
In addition, it triggers venous stasis that promotes fluid retention and consequent conjunctival edema (chemosis). All this succession of events related to IMV promotes the incomplete eyelid closure (15)(16) .
Patients using sedatives have the inability to completely close the eyelids by relaxing the oculomotor muscles. This inability leads to exposure of the conjunctiva and results in drying of the ocular surface. The degree of exposure is linked to the depth of sedation (17) . Other studies have also found associations between dry eye signs and corticosteroids, but plausible explanations for this association was not found (3,8) .
The conjunctiva redness results from the presence of dilated blood vessels on the ocular surface and is mainly triggered by insufficient lubrication of the eyes or their exposure to air with low humidity. In order to evaluate the problems involving the Dry Eye in ICU patients, a study identified that conjunctival hyperemia was the most frequently observed ocular problem, present in 56.25% of the patients analyzed (13) .
Similarly, the results of this study showed that the score 4 (conjunctival hyperemia) was the second most prevalent (32.5%) in detriment of the other indicators and, when statistically associated, it is possible to observe an association with the use of vasoconstrictors and benzodiazepines.
Medications such as vasoconstrictors that inhibit parasympathetic activity are strongly related to eye dryness because of reduce lacrimal production.
Benzodiazepines are related as a predisposing factor to hyperemia, although not directly. Acting as sedatives and promoting muscle relaxation by decelerating organic function, thus, incomplete eyelid closure promotes corneal exposure, evaporation of the tear film, dryness and consequent hyperemia, which indicates a process of acute inflammation (3) .
Regarding the indicator Excessive mucous secretion, it is discussed that the hyperactivity of the caliciform glands in the conjunctiva may lead to an excessive production of mucous secretion and is usually the result of a previous inflammatory state.
When present, the secretion is located on the ocular surface and its aspect is of whitish coloration in format of filaments or plates. A recent study found that the absence of ocular hyperemia (p<0.001), of mucous secretion (p<0.045) and the non-use of sedatives (p<0.025) were significantly associated with the absence of the Dry eye (3) .
In this study, this indicator was statistically associated with the use of invasive mechanical ventilation. It was discussed above that the use of IMV significantly alters the homeostasis of the eye by predisposing the appearance of conjunctival edema and successively the dry eye. Mucous secretion occurs in the last phase of this process of dryness caused by exposure as an inflammatory sign of the mucin-producing glands, which is a late sign of the phenomenon (16) .
The indicator Decreased blinking mechanism showed statistical significance with: hospitalization for neurological disorders, IMV, chemosis, sedatives, antibiotics, benzodiazepines and corticosteroids.
The blinking reflex periodically promotes uniform distribution of the tear over the entire eye surface. When it is diminished, the tear film ruptures occurs and the dryness protection mechanism fails.
Spontaneous and effective blinking of the eyes (5 to 10 blinks/second) prevents evaporation of the tear between blinks, eliminates foreign bodies, excludes visual stimuli and ensures the optical quality of the eye by spreading and distributing the tear film over the eye surface (18) .
The IMV and chemosis variables converge to the decrease in the blinking mechanism, as discussed above, the use of this ventilatory device promotes the accumulation of liquids in the conjunctiva that originates the chemosis (3) .
Regarding sedatives, the variable with a higher prevalence ratio, studies point out that, as in lagophthalmos, the loss of the blinking reflex is observed in patients with low level of consciousness and high depth of sedation level. Sedatives and muscle relaxants may suppress the act of blinking, preventing an adequate distribution of the tear on the ocular surface (19) . for a more assertive targeting of the impairment of the problems found.

Conclusion
This study allowed assessing the degree of ocular