See the improvement with tailored treatment of dry eye disease

In our previous article (see “Eye health”, New Zealand Doctor, 17 August), we discussed the diagnosis of dry eye disease (DED) and its classification into evaporative dry eye (EDE) and aqueous-deficient dry eye (ADDE). It can be difficult to classify DED as either EDE or ADDE in GP practice because specialised equipment is required to make a definitive diagnosis, but treatment should be tailored to the type of DED.

The previous article discussed some practical diagnostic tests that can be carried out in general practice. As a rule of thumb, most DED patients will have EDE related to meibomian gland dysfunction (MGD). A study of 224 patients with DED found only 10 per cent were classified as having purely ADDE, whereas 86 per cent demonstrated signs of MGD.¹ Furthermore, of patients with significant ADDE, only 10 per cent are likely to have Sjögren syndrome.²

For all types of DED, managing modifiable risk factors is the first step in treatment. Computer use is strongly linked with DED.^3–6 Patients should be counselled on reducing computer screen time when possible, and on taking breaks and performing blinking exercises to reduce the drying effects of computer use on the ocular surface.

Air conditioning and environments with low humidity can also contribute significantly to DED.⁷ Increasing humidity by reducing air conditioning or using humidifiers can be beneficial. Using an oil-based eye drop, such as Systane Complete, can reduce the effects of adverse environments.⁸

Contact lens wear is another significant modifiable risk factor for DED.⁹ Dryness is reported in 40 per cent of people who wear contact lenses, and 25 per cent experience moderate to severe symptoms,^10,11 leading to decreased wearing times.¹² In fact, the tear film on top of the contact lens has been found to more closely resemble that found in patients with Sjögren syndrome than the normal tear film, in terms of stability and behaviour.¹³

If the DED patient wears contact lenses, referral to their optometrist is warranted to assess whether changing the lens material or modality (eg, from monthly to daily disposables) may be beneficial. The optometrist may also recommend reducing contact lens wear or taking a contact lens holiday to allow the ocular surface to stabilise.

Some medications, such as antihistamines, antidepressants, anxiolytics as well as isotretinoin, have been consistently linked with DED.¹⁴

The GP is in an ideal position to check whether medications can be altered to help a patient’s DED.

Warm compresses are very effective in the treatment of meibomian gland dysfunction, even in cases of severe gland dropout

Warm compresses use a heated material (eg, eye mask or wheat bag) that is placed on the closed eye for a period of time, followed by digital pressure on the upper and lower lids. Warm compresses are very effective in the treatment of MGD,^15–18 even in cases of severe gland dropout.¹⁵

Treatment should be between five and 10 minutes in duration, and performed a minimum of once, but preferably twice, each day.^{15,17,19–21} It takes at least two weeks to see an improvement in symptoms, and four to eight weeks to see improvements in clinical signs of dry eye.

Hot flannels are not effective as warm compresses unless the “bundle method” is used (see tinyurl.com/DED-WarmCompress for more information on this technique).¹⁸ If a wheat bag is used, it should be reheated after five minutes and placed on the eyes for another five minutes to ensure the required level of heat is maintained for long enough.²²

Omega-3 fatty acid supplements have been shown to be effective in treating DED^23,24 by improving meibomian gland expression, meibum quality, tear osmolarity and tear break-up time.²⁵ It is hypothesised that omega-3s target meibum by breaking it down from the more solid form found in MGD to a more normal, liquid form.^26,27

A 12-week course of oral omega-3 supplementation has been shown to have similar anti-inflammatory effects to a two-week course of a weak topical corticosteroid (fluorometholone 0.1 per cent). To achieve the desired clinical effect, a high daily dosage of eicosapentaenoic acid (EPA) 1000mg and docosahexaenoic acid (DHA) 500mg is recommended,^25,28 which is approximately two high-strength, 1000–1500mg fish oil capsules.

Doxycycline is a tetracycline antibiotic that has been shown to improve and restore the lipid properties of meibum.²⁹ It is thought to have both antibacterial and anti-inflammatory effects in MGD,^29,30 and to improve signs and symptoms of MGD, blepharitis and DED.^31–39

A wide variety of treatment periods and dosages are reported, varying from one to 16 weeks, and from 40mg to 400mg per day.^31–39 No clear evidence exists to support the use of a particular regimen and dosage at present. We typically prescribe 100mg per day for three months.

Azithromycin is a macrolide antibiotic with documented anti-inflammatory properties.^40,41 It has been shown to improve tear film stability in DED and to significantly improve clinical signs of MGD.^33,42,43

Similar to doxycycline, no clear dosage regimens can be extracted from the current evidence, but a recent randomised controlled trial reported a superior clinical response when compared with doxycycline.³⁵ We typically prefer azithromycin to doxycycline and prescribe 500mg for one day, then 250mg per day for four days.

ADDE is subdivided into Sjögren syndrome dry eye (SSDE) and non-Sjögren syndrome dry eye (NSDE). Patients with dry eye symptoms and a dry mouth should be investigated for Sjögren syndrome and may benefit from rheumatology specialist input.

Artificial tears are an effective treatment for dry eye and are indicated in both ADDE and EDE.⁴⁴ They are the main treatment GPs can offer patients with ADDE. A recent prospective, multicentre, double-masked, parallel-group, randomised controlled trial found that after six months of treatment with Systane eye drops (either Ultra or Complete) four times per day, 19 per cent of patients no longer fulfilled the diagnostic criteria for DED.⁴⁵

The authors state, “this relatively late onset, but sustained change…suggests that there may be more than a simple transient effect at play”.⁴⁵ This indicates that prolonged treatment with artificial tears has a sustained therapeutic effect on the ocular surface, likely caused by restoration of physiological homeostasis and stabilisation of the tear film.

Non-preserved drops are often preferred in patients using more than six drops per day, and GPs can submit a request for Special Authority to prescribe subsidised, non-preserved artificial tears (eg, Hylo-Fresh or Systane Unit Dose). This is especially important for patients with ADDE as they tend to require very frequent drop use, which can cause ocular surface disturbance if preserved drops are used.⁴⁶

Referral to a dry eye specialist (optometrist or ophthalmologist) for more advanced treatments (eg, LipiFlow, intense pulsed light, autologous serum eye drops, punctal plugs) is indicated if patients do not respond to the treatments outlined above.

Ryan Mahmoud is an optometrist and a dry eye and contact lens specialist at NVision Eyecare; Mo Ziaei is a senior lecturer at the University of Auckland and a cataract, cornea and anterior segment specialist at Greenlane Clinical Centre and Re:Vision Laser & Cataract, Auckland