Table 10.
Staging the Severity of MGD-Related Ocular Surface Disease
| Severity Level |
||||||
|---|---|---|---|---|---|---|
| Level 0 Normal | Level 1 Subclinical | Level 2 Minimally Symptomatic | Level 3 Mildly Symptomatic | Level 4 Moderately Symptomatic | Level 5 Severely Symptomatic | |
| Symptom frequency and severity | No symptoms | Asymptomatic or occasional symptoms | Some of the time. | Half the time | Most of the time | All the time |
| Precipitated by environmental factors | Some limitation of activity | Frequent limitation of activity | Severe/disabling/constant | |||
| OSDI range (0–100) | 0 | 0–12 | 0–12 | 13–22 | 23–32 | 33–100 |
| TFBUT, s | ≥10 | <10 to ≥7 | <7 to ≥5 | <5 to ≥3 | <3 to ≥1 | <1 or instant breakup |
| Tear osmolarity, mOsM | Normal <308 | Normal <308 | Normal <308 | Mildly increased >308 to ≤313 | Moderately increased >314 to ≤317 | Markedly increased >317 |
| Conjunctival hyperemia | Nil | Minimal | Mild | Moderate | Marked | |
| CCLRU | Nil | Nil | CCLRU 1 | CCLRU 2 | CCLRU 3 | CCLRU 4 |
| Ocular surface staining | 0 | Nil | Minimal | Mild | Moderate | Severe |
| Oxford scale (0–15) | 0 | Nil | 0–3 | 4–6 | 7–10 | 11–15 |
| NEI Industry scale (0–33) | 0 | Nil | 0–7 | 8–14 | 15–23 | 24–33 |
| Schirmer score, mm | ≥10 | ≥10 | <10 to ≥7 | <7 to ≥5 | <5 to ≥3 | <3 |
| Treatment of MGD-related ocular surface disease | No treatment | No treatment | + Artificial tear substitutes | + Alternative AT selection | + Alternative AT selection | + Alternative AT selection |
| + Simple viscosity agents (preservatives allowable at low frequency of use) | + Immune modulation | + Gels and ointments | + Autologous serum | |||
| ± Punctal plugs | + Conserving spectacles | |||||
| ± Moisture conserving spectacles | + Surgical procedures | |||||
This should be read in conjunction with Table 9 which provides a staging scheme for MGD. Increasing MGD severity is perceived to lead to impaired spreading and stability of the tear film lipid layer, increased evaporative water loss, increased tear osmolarity, and ocular surface damage, which leads to conjunctival hyperemia and symptoms. These events are accompanied by inflammatory responses in the lids and on the ocular surface. Each measured parameter scales from least to most severe disease in five levels of severity. The numerical divisions are literature based, but require further validation. In an individual patient, it is unlikely that stages will lie in register for each parameter, but a global score can be generated by summing grades within the levels. Extensive MGD can be a cause of evaporative dry eye rather than aqueous-deficient dry eye. However, the Schirmer test is included in the battery of tests, to allow for the coinciding occurrence of both conditions. Treatment is based on symptoms, ocular surface damage and disturbed tear dynamics. For details, see the Report on Management and Therapy. Recommended treatments are additive at each level. At each clinical assessment, lack of response to treatment at the previous level moves treatment to the next level. ±, the decision to use this treatment is based on clinical judgement; +, treatment is recommended at this level. MGD, meibomian gland dysfunction; AT, artificial tears; CCLRU, Cornea and Contact Lens Research Unit (School of Optometry and Vision Science, University of New South Wales, Sydney, Australia); NEI, National Eye Institute; OSDI, Ocular Surface Disease Index.