The MGDRx Eyebag for MGD-Related Evaporative Dry Eye
The results demonstrate statistically significant improvements in meibomian gland dropout, TMH, osmolarity, conjunctival hyperaemia and staining in test eyes only (Table 1). Given that measurements were taken on two separate occasions, it was not possible to determine a natural history of the treatment approach. It is likely that the frequent and regular heating melted the abnormal meibum, clearing the obstruction within the meibomian gland, allowing the meibum to secrete on the eyelid margin. The increased quantity of meibum available may, therefore, help thicken and restore normal tear film lipid layer function such that evaporation of the underlying aqueous is prevented, tear film stability is improved, tear film osmolarity and ocular surface staining reduced and tear film meniscus height increased. This is supported by the significant positive correlation observed between lipid layer thickness and tear film stability. Furthermore, meibum quantity or evaporation rates have previously been shown to positively correlate with tear film stability.
Indeed, NITBUT (by 1.9±1.3 s) and tear film lipid layer thickness (by 1.1±0.8 grades) demonstrated a statistically significant increase following heat treatment. Although a recent study investigating the effect of warm moist air goggles in MGD patients found no statistically significant increase in tear film stability 10 min after use, Olson et al (2003) found an 80% increase in lipid layer thickness in MGD-related dry eye patients after 5 min into treatment with warm moist compress heated to 40°C for 30 min, and 66% increase 5 min after removal. Thus, it may be that improvements in tear film stability and lipid layer thickness in MGD patients can only be achieved where eyelid warming devices make contact with the eyelids.
Meibomian gland function also improved with the heated eyebag after the treatment period, where there were statistically significant improvements in meibum quality and expressibility in test eyes. However, the improvement in meibum quality compared to control eyes was only statistically significant between the lower eyelids. At baseline, meibum quality grade on the lower eyelid was significantly greater than the upper eyelid of test and control eyes, such that the upper eyelid was considered normal—thus, improvements in meibum quality may only have been detected in the lower eyelids owing to the limited resolution of the grading scale. Of interest was the statistically significant improvement in expressibility in control eyes (composite reduction of 0.35±0.81). The non-heated eyebag may have warmed the eyelids by insulating and preventing heat loss, which subsequently brought about an improvement in the abnormal meibum. The frequent application of the eyebag with the hands may have also massaged the eyelids to help clear the obstructed glands. Since the heated and non-heated eyebags were applied at the same time and duration, this massaging effect may have contributed at least in part to the greater improvement in expressibility observed in test eyes (composite reduction of 0.80±0.70). With respect to the semiquantitative nature of the grading scale, eyelids with 5, 6, or 7 expressible glands were recorded as 'grade 1'—thus, the improvements observed may have been underestimated.
Furthermore, a statistically significant improvement in ocular symptoms was also observed in test eyes only. Surprisingly, the improvement in ocular comfort scores was observed as early as the evening of treatment Day 1, suggesting that the eyebag produces an increase in ocular comfort for at least 12 h following single use. Although subjects still had raised ocular comfort at around 6 months after the trial, comfort was maintained best in those who continued treatment 1–8 times a month. It should be noted that subjects were not masked and, therefore, some placebo effect could be possible, although the effect was marked and occurred in all subjects.
Eyelid warming therapy associated with eyelid massage has been suggested to induce corneal deformation due to increases in corneal temperature, and with concurrent massaging, possible ectasia. Only one case of corneal deformation following such treatment has been reported, but the duration of treatment in this case was far longer (15 min twice a day for 7 weeks) than that prescribed herein. Transient visual degradation without changes in corneal topography has been observed after warm compresses (45°C) were applied every 2 min for 30 min without massage, but again the duration of treatment and peak temperature was sustained for longer than the present study and the treatment method is not typically advised to MGD patients. Therefore, it appears that corneal deformation and/or visual changes, may only occur following unusually long and intense treatment application durations and long-term therapy associated with eyelid rubbing.
Given there was no reduction in visual acuity and no change in corneal topography from baseline after the treatment period, the risk of corneal deformation with the MGDRx EyeBag, as prescribed, appears to be minimal. Further, there was a statistically significant improvement in ocular surface staining (particularly the cornea) and conjunctival hyperaemia in test eyes. Thus, when used based upon the treatment regimen prescribed herein, the MGDRx EyeBag may be considered a safe and effective eyelid warming device with a low risk of corneal deformation and visual changes, and results in improved comfort and tear film parameters involved in evaporative dry eye in patients with MGD.
Discussion
The results demonstrate statistically significant improvements in meibomian gland dropout, TMH, osmolarity, conjunctival hyperaemia and staining in test eyes only (Table 1). Given that measurements were taken on two separate occasions, it was not possible to determine a natural history of the treatment approach. It is likely that the frequent and regular heating melted the abnormal meibum, clearing the obstruction within the meibomian gland, allowing the meibum to secrete on the eyelid margin. The increased quantity of meibum available may, therefore, help thicken and restore normal tear film lipid layer function such that evaporation of the underlying aqueous is prevented, tear film stability is improved, tear film osmolarity and ocular surface staining reduced and tear film meniscus height increased. This is supported by the significant positive correlation observed between lipid layer thickness and tear film stability. Furthermore, meibum quantity or evaporation rates have previously been shown to positively correlate with tear film stability.
Indeed, NITBUT (by 1.9±1.3 s) and tear film lipid layer thickness (by 1.1±0.8 grades) demonstrated a statistically significant increase following heat treatment. Although a recent study investigating the effect of warm moist air goggles in MGD patients found no statistically significant increase in tear film stability 10 min after use, Olson et al (2003) found an 80% increase in lipid layer thickness in MGD-related dry eye patients after 5 min into treatment with warm moist compress heated to 40°C for 30 min, and 66% increase 5 min after removal. Thus, it may be that improvements in tear film stability and lipid layer thickness in MGD patients can only be achieved where eyelid warming devices make contact with the eyelids.
Meibomian gland function also improved with the heated eyebag after the treatment period, where there were statistically significant improvements in meibum quality and expressibility in test eyes. However, the improvement in meibum quality compared to control eyes was only statistically significant between the lower eyelids. At baseline, meibum quality grade on the lower eyelid was significantly greater than the upper eyelid of test and control eyes, such that the upper eyelid was considered normal—thus, improvements in meibum quality may only have been detected in the lower eyelids owing to the limited resolution of the grading scale. Of interest was the statistically significant improvement in expressibility in control eyes (composite reduction of 0.35±0.81). The non-heated eyebag may have warmed the eyelids by insulating and preventing heat loss, which subsequently brought about an improvement in the abnormal meibum. The frequent application of the eyebag with the hands may have also massaged the eyelids to help clear the obstructed glands. Since the heated and non-heated eyebags were applied at the same time and duration, this massaging effect may have contributed at least in part to the greater improvement in expressibility observed in test eyes (composite reduction of 0.80±0.70). With respect to the semiquantitative nature of the grading scale, eyelids with 5, 6, or 7 expressible glands were recorded as 'grade 1'—thus, the improvements observed may have been underestimated.
Furthermore, a statistically significant improvement in ocular symptoms was also observed in test eyes only. Surprisingly, the improvement in ocular comfort scores was observed as early as the evening of treatment Day 1, suggesting that the eyebag produces an increase in ocular comfort for at least 12 h following single use. Although subjects still had raised ocular comfort at around 6 months after the trial, comfort was maintained best in those who continued treatment 1–8 times a month. It should be noted that subjects were not masked and, therefore, some placebo effect could be possible, although the effect was marked and occurred in all subjects.
Eyelid warming therapy associated with eyelid massage has been suggested to induce corneal deformation due to increases in corneal temperature, and with concurrent massaging, possible ectasia. Only one case of corneal deformation following such treatment has been reported, but the duration of treatment in this case was far longer (15 min twice a day for 7 weeks) than that prescribed herein. Transient visual degradation without changes in corneal topography has been observed after warm compresses (45°C) were applied every 2 min for 30 min without massage, but again the duration of treatment and peak temperature was sustained for longer than the present study and the treatment method is not typically advised to MGD patients. Therefore, it appears that corneal deformation and/or visual changes, may only occur following unusually long and intense treatment application durations and long-term therapy associated with eyelid rubbing.
Given there was no reduction in visual acuity and no change in corneal topography from baseline after the treatment period, the risk of corneal deformation with the MGDRx EyeBag, as prescribed, appears to be minimal. Further, there was a statistically significant improvement in ocular surface staining (particularly the cornea) and conjunctival hyperaemia in test eyes. Thus, when used based upon the treatment regimen prescribed herein, the MGDRx EyeBag may be considered a safe and effective eyelid warming device with a low risk of corneal deformation and visual changes, and results in improved comfort and tear film parameters involved in evaporative dry eye in patients with MGD.
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