Diagnosing the Severity of Dry Eye
Diagnosing the Severity of Dry Eye
Following extensive review of current knowledge, questionnaire results analysis and discussion, the ODISSEY European Consensus Group defined a two-step scoring algorithm for diagnosing severe DED (figure 2). The algorithm addresses the challenge of symptom and sign discordance in some cases of severe DED, and describes specific criteria relevant to evaluating DED severity in three different patient scenarios.
(Enlarge Image)
Figure 2.
Consensus derived scoring algorithm for severe DED diagnosis. DED, dry eye disease, TBUT, tear break-up time, sec, second, CFS, corneal fluorescein staining, OSDI, Ocular Surface Disease Index.
The first step of the scoring algorithm evaluates the minimum number of fundamental criteria required for severe DED diagnosis. It was recommended by the panel that just two criteria, a symptomatic assessment and an evaluation of ocular surface damage by CFS would be sufficient to adequately evaluate severity for the majority of patients. These two criteria are discussed below.
Symptomatology and CFS as the Primary Assessment Criteria. DED symptoms of ocular discomfort and visual disturbance can seriously impact patients' quality of life. The Food and Drug Administration (FDA) has emphasised the importance of patient-reported outcomes as clinical endpoints in ophthalmological trials, and a number of validated questionnaires have been developed to assess symptoms of dry eye. These tools are generally economically viable, correlate well with quality of life, have good sensitivity for DED diagnosis, and can be easily quantified. However, the panel also acknowledged that symptom assessments may not be easily reproducible, are not necessarily specific for DED, and their use may carry a risk of overtreatment. The Ocular Surface Disease Index (OSDI) is one of the most widely used questionnaires. The OSDI and similar tools have been shown to correlate moderately well with disease severity, and to a similar degree as corneal staining (eg, r=0.41 vs r=0.43, respectively). However, other studies show poor correlation. Nevertheless, it is generally accepted that an OSDI score of around 30 or over is necessary for diagnosis of severe DED.
CFS is a widely used diagnostic test useful for assessing the health of the cornea. CFS was considered by the panel to be the single most appropriate test of DED signs. It is easy to perform, inexpensive, reproducible and can correlate with visual acuity and disease severity. CFS requires a standardised assessment procedure; also no method of objective quantification is available. However, a score ≥3 on the Oxford Scheme generally indicates severe DED. It must also be remembered that CFS will stain all corneal damage non-specifically, irrespective of cause (eg, refractive laser surgery and drug toxicity). Ambiguous, asymmetrical and artefact staining patterns can also be an issue, as can sensitivity in mild disease (similar to all known markers of DED).
Following discussion, ODISSEY members decided that combined use of CFS and symptom-based assessment can provide a reliable 'frontline' diagnostic approach for evaluation of DED severity, and that an OSDI score ≥33 and CFS score ≥3 on the Oxford scheme is enough to clearly establish a diagnosis of severe DED in those patients whose signs and symptoms of disease associate well. Thus, it was recommended that these criteria should be adopted for Step 1 of the diagnostic algorithm (figure 2). However, in cases of discordance, it was recommended that further additional evaluations are needed in order to improve diagnostic specificity.
The panel agreed that when there is discordance between DED signs and symptoms, that is, when OSDI and CFS severity scorings are not in agreement, additional criteria are necessary to establish severe DED. Three possible outcomes after CFS and OSDI assessment in Step 1 were defined:
The disposition of each patient in Step 2 (ie, Scenario A, B, or C) determines the additional criteria recommended to further evaluate DED severity.
The clinical and biological signs were divided by the panel into two groups. Each criterion was labelled as either being 'determinant' or 'contributory' to diagnosis of severe DED. A summary of the issues discussed by the panel with regards to each criterion is outlined in Table 1 for criteria defined as determinant, and Table 2 for criteria defined as contributory.
Determinant Criteria. Eight of the criteria were classed as determinant to diagnosis of severe DED, and are listed in Table 1. The score cut-offs, or grading, which were considered by the panel to indicate severe disease are also presented. Regardless of the scenario (ie, A, B, or C), the presence of just one of these clinical criteria in addition to OSDI or corneal fluorescein staining (CSF) severe grading was accepted as diagnosis of severe DED.
Contributory Criteria. Contributory criteria are listed in Table 2 and include aberrometry, confocal microscopy, inflammatory markers and refractory to standard disease treatments. Although these criteria have been shown to play a potentially important role in DED diagnosis and severity evaluation (see and Table 2), they were categorised as 'contributory' by the panel as their validity is not yet well established, and they are not yet routinely evaluated in the clinical setting. Similarly, there exist no standardised methods for evaluating their outcome.
Other Contributory Factors. TBUT was considered by the panel to have a specialised role in the diagnosis and evaluation of DED. TBUT is a routine test for tear instability, and the panel agreed that it is essential for confirming/verifying diagnosis of dry eye in cases of a high symptomatology score with a negative or low CFS score (ie, Scenario C). However, the methodology is far from standardised (see Table 2), and the resulting wide variation in test performance can lead to misinterpretation of TBUT findings. The panel, therefore, added the caveat that TBUT must be regarded as a 'contributory' criterion in patient scenarios where CFS-determined ocular damage is high but symptom severity is low (ie, Scenario A), or if symptom severity is high but ocular damage is borderline (ie, Scenario B).
The hierarchy of determinant and contributory factors for each scenario, as determined by panel consensus is outlined in Table 3. The specific evaluation pathway for each scenario is discussed below and shown in figure 2.
Scenario A: OSDI<33 and CFS Score≥3. If the patient presents significant ocular damage determined by CFS, but symptom severity is relatively mild, the additional presence of one or more of the determinant factors listed in Table 3 is sufficient to establish severe DED diagnosis. The panel noted that in this scenario, diminished corneal sensitivity should also be considered as an additional determinant sign. The presence of deeply impaired corneal sensitivity plus a CFS score ≥3 would therefore be sufficient to establish severe DED in this clinical setting.
Scenario B: OSDI≥33 and CFS=grade 2. If symptom score is high, but CFS ocular signs do not quite meet the panel-defined level for severe DED, the panel determined that the presence of one of the additional determinant factors listed in Table 3 is sufficient to establish severe DED diagnosis. However, the algorithm for Scenario B is distinct from Scenario A in that corneal sensitivity is not considered as a determinant factor in this case. This is because the OSDI score already confirms adequate corneal sensitivity.
Scenario C: OSDI≥33 and CFS≤1. Scenario C represents major discordance between symptoms and CFS grading, and as such, requires particular attention. The panel recommended that if reported symptoms are severe, but there is no immediate correlation with clinical signs as assessed by CFS grade, the diagnosis of DED should be reconsidered (but not necessarily discarded). Use of the TBUT test in this scenario is, therefore, a prerequisite as a preliminary step (see figure 2) to evaluate tear film instability and confirm the original diagnosis of DED. A more comprehensive understanding of the patient case is also necessary (eg, use of an in-depth patient questionnaire to further determine quality of life, mood evaluation, etc.).
It is of note that filamentary keratitis is not considered as an additional determinant criteria in the case of Scenario C, as objective ocular symptoms determined by CFS have already been confirmed as mild (Table 3). Similar to Scenario B, corneal sensitivity testing is not required, as the OSDI score is satisfactory.
A Simplified and Practical Approach to Evaluating Ded Severity
Following extensive review of current knowledge, questionnaire results analysis and discussion, the ODISSEY European Consensus Group defined a two-step scoring algorithm for diagnosing severe DED (figure 2). The algorithm addresses the challenge of symptom and sign discordance in some cases of severe DED, and describes specific criteria relevant to evaluating DED severity in three different patient scenarios.
(Enlarge Image)
Figure 2.
Consensus derived scoring algorithm for severe DED diagnosis. DED, dry eye disease, TBUT, tear break-up time, sec, second, CFS, corneal fluorescein staining, OSDI, Ocular Surface Disease Index.
Step 1: Fundamentals of Severe DED Diagnosis
The first step of the scoring algorithm evaluates the minimum number of fundamental criteria required for severe DED diagnosis. It was recommended by the panel that just two criteria, a symptomatic assessment and an evaluation of ocular surface damage by CFS would be sufficient to adequately evaluate severity for the majority of patients. These two criteria are discussed below.
Symptomatology and CFS as the Primary Assessment Criteria. DED symptoms of ocular discomfort and visual disturbance can seriously impact patients' quality of life. The Food and Drug Administration (FDA) has emphasised the importance of patient-reported outcomes as clinical endpoints in ophthalmological trials, and a number of validated questionnaires have been developed to assess symptoms of dry eye. These tools are generally economically viable, correlate well with quality of life, have good sensitivity for DED diagnosis, and can be easily quantified. However, the panel also acknowledged that symptom assessments may not be easily reproducible, are not necessarily specific for DED, and their use may carry a risk of overtreatment. The Ocular Surface Disease Index (OSDI) is one of the most widely used questionnaires. The OSDI and similar tools have been shown to correlate moderately well with disease severity, and to a similar degree as corneal staining (eg, r=0.41 vs r=0.43, respectively). However, other studies show poor correlation. Nevertheless, it is generally accepted that an OSDI score of around 30 or over is necessary for diagnosis of severe DED.
CFS is a widely used diagnostic test useful for assessing the health of the cornea. CFS was considered by the panel to be the single most appropriate test of DED signs. It is easy to perform, inexpensive, reproducible and can correlate with visual acuity and disease severity. CFS requires a standardised assessment procedure; also no method of objective quantification is available. However, a score ≥3 on the Oxford Scheme generally indicates severe DED. It must also be remembered that CFS will stain all corneal damage non-specifically, irrespective of cause (eg, refractive laser surgery and drug toxicity). Ambiguous, asymmetrical and artefact staining patterns can also be an issue, as can sensitivity in mild disease (similar to all known markers of DED).
Following discussion, ODISSEY members decided that combined use of CFS and symptom-based assessment can provide a reliable 'frontline' diagnostic approach for evaluation of DED severity, and that an OSDI score ≥33 and CFS score ≥3 on the Oxford scheme is enough to clearly establish a diagnosis of severe DED in those patients whose signs and symptoms of disease associate well. Thus, it was recommended that these criteria should be adopted for Step 1 of the diagnostic algorithm (figure 2). However, in cases of discordance, it was recommended that further additional evaluations are needed in order to improve diagnostic specificity.
Step 2: Additional Criteria for Severe DED Diagnosis
The panel agreed that when there is discordance between DED signs and symptoms, that is, when OSDI and CFS severity scorings are not in agreement, additional criteria are necessary to establish severe DED. Three possible outcomes after CFS and OSDI assessment in Step 1 were defined:
Scenario A: if OSDI<33 and CFS≥3. Symptomatology is not indicative of severe disease despite severe ocular surface damage.
Scenario B: if OSDI≥33 and CFS=2. Symptomatology is severe, but ocular surface damage is borderline or inconclusive.
Scenario C: if OSDI≥33 and CFS≤1. Symptomatology is severe, but ocular surface damage is not particularly evident.
The disposition of each patient in Step 2 (ie, Scenario A, B, or C) determines the additional criteria recommended to further evaluate DED severity.
The clinical and biological signs were divided by the panel into two groups. Each criterion was labelled as either being 'determinant' or 'contributory' to diagnosis of severe DED. A summary of the issues discussed by the panel with regards to each criterion is outlined in Table 1 for criteria defined as determinant, and Table 2 for criteria defined as contributory.
Determinant Criteria. Eight of the criteria were classed as determinant to diagnosis of severe DED, and are listed in Table 1. The score cut-offs, or grading, which were considered by the panel to indicate severe disease are also presented. Regardless of the scenario (ie, A, B, or C), the presence of just one of these clinical criteria in addition to OSDI or corneal fluorescein staining (CSF) severe grading was accepted as diagnosis of severe DED.
Contributory Criteria. Contributory criteria are listed in Table 2 and include aberrometry, confocal microscopy, inflammatory markers and refractory to standard disease treatments. Although these criteria have been shown to play a potentially important role in DED diagnosis and severity evaluation (see and Table 2), they were categorised as 'contributory' by the panel as their validity is not yet well established, and they are not yet routinely evaluated in the clinical setting. Similarly, there exist no standardised methods for evaluating their outcome.
Other Contributory Factors. TBUT was considered by the panel to have a specialised role in the diagnosis and evaluation of DED. TBUT is a routine test for tear instability, and the panel agreed that it is essential for confirming/verifying diagnosis of dry eye in cases of a high symptomatology score with a negative or low CFS score (ie, Scenario C). However, the methodology is far from standardised (see Table 2), and the resulting wide variation in test performance can lead to misinterpretation of TBUT findings. The panel, therefore, added the caveat that TBUT must be regarded as a 'contributory' criterion in patient scenarios where CFS-determined ocular damage is high but symptom severity is low (ie, Scenario A), or if symptom severity is high but ocular damage is borderline (ie, Scenario B).
The hierarchy of determinant and contributory factors for each scenario, as determined by panel consensus is outlined in Table 3. The specific evaluation pathway for each scenario is discussed below and shown in figure 2.
Scenario A: OSDI<33 and CFS Score≥3. If the patient presents significant ocular damage determined by CFS, but symptom severity is relatively mild, the additional presence of one or more of the determinant factors listed in Table 3 is sufficient to establish severe DED diagnosis. The panel noted that in this scenario, diminished corneal sensitivity should also be considered as an additional determinant sign. The presence of deeply impaired corneal sensitivity plus a CFS score ≥3 would therefore be sufficient to establish severe DED in this clinical setting.
Scenario B: OSDI≥33 and CFS=grade 2. If symptom score is high, but CFS ocular signs do not quite meet the panel-defined level for severe DED, the panel determined that the presence of one of the additional determinant factors listed in Table 3 is sufficient to establish severe DED diagnosis. However, the algorithm for Scenario B is distinct from Scenario A in that corneal sensitivity is not considered as a determinant factor in this case. This is because the OSDI score already confirms adequate corneal sensitivity.
Scenario C: OSDI≥33 and CFS≤1. Scenario C represents major discordance between symptoms and CFS grading, and as such, requires particular attention. The panel recommended that if reported symptoms are severe, but there is no immediate correlation with clinical signs as assessed by CFS grade, the diagnosis of DED should be reconsidered (but not necessarily discarded). Use of the TBUT test in this scenario is, therefore, a prerequisite as a preliminary step (see figure 2) to evaluate tear film instability and confirm the original diagnosis of DED. A more comprehensive understanding of the patient case is also necessary (eg, use of an in-depth patient questionnaire to further determine quality of life, mood evaluation, etc.).
It is of note that filamentary keratitis is not considered as an additional determinant criteria in the case of Scenario C, as objective ocular symptoms determined by CFS have already been confirmed as mild (Table 3). Similar to Scenario B, corneal sensitivity testing is not required, as the OSDI score is satisfactory.
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