Dry eye research review

Clinical trial of platelet-rich plasma injection for severe dry eye 

Avila, Marcel Y, Angela Igua, and Amparo Mora  

British Journal of Ophthalmology 103.5 (2019): 648-653 

This is a randomised, prospective intervention study that evaluated the effectiveness of platelet-rich plasma (PRP) injections in the treatment of severe, aqueous-deficient dry eye. PRP is a blood derivative that has previously been successfully used to treat ocular surface disorders such as persistent epithelial defects.

The study involved subjects with severe dry eye who had been diagnosed with Sjögren’s syndrome. Subjects were divided into two groups: The intervention group received injections of PRP directly into the lacrimal gland as well has hyaluronic acid, preservative free artificial tears, while the control group received the same artificial tear drops with the same frequency.

The intervention group showed a significant improvement in all outcome measures, compared to baseline and compared to the control group. Investigators also observed an increase of approximately 64% in lacrimal volume from baseline among Sjögren’s syndrome patients with severe lacrimal alteration. The control group showed no improvement in any of the outcomes measured. Study authors concluded that PRP injections are safe and effective in improving tear parameters and subjective comfort in severe dry eye.

The study shows much promise for PRP as a novel treatment of severe, aqueous deficient dry eye. Currently, treatments are only palliative. This makes an approach that attempts to regenerate lacrimal gland tissue very appealing.

The study had some limitations including a small sample size and a lack of subject and personnel blinding. Its use of invasive tests, namely Schirmer’s and fluorescein tear breakup time, is slightly outdated as there are less invasive and more accepted tests now available. Further studies with larger sample sizes, more robust designs and less invasive clinical tests are needed to validate the results. The longevity of the treatment’s effect is also not well documented at present.

 

The efficiency of Cyclosporine A-Eluting CLs for dry eye  

Choi, Jung Han, et al 

Current eye research 44.5 (2019): 486-496 

This study was carried out on rabbits to evaluate the effectiveness of Cyclosporine A (CsA)-eluting contact lenses (CLs) for the treatment of dry eye. Rabbits were fitted with CsA-laden hydrogel to investigate whether the CsA-CL achieved sustained release of CsA in vivo and in vitro.

In vitro results showed that CsA was gradually released from CsA-CL. The concentration of CsA was maintained within the therapeutic range for 48 hours. Penetration of the drug was documented in the cornea, conjunctiva and crystalline lens. In vivo results showed the CsA-CL was significantly superior in all in vivo measurements, such as tear volume and breakup time, compared to the control groups.

The authors concluded that the CsA-eluting CL had a sustained drug release and showed good ocular penetration. The newly designed CL also improved clinical parameters and increased conjunctival goblet cell density and reduced expression of inflammatory cytokines.

Silicone hydrogel CLs were not used in this study as they are not as effective at drug release as hydrogel materials. Although this is a limitation, the availability of a sustained drug release treatment would still be clinically advantageous should this product become commercially available.

The authors did not address the fact that contact lens wear has been linked with dry eye. This could mean that this novel treatment may be categorised as a short-term treatment option that replaces eye drops, as opposed to a long-term treatment option.

 

TearCare - a novel system of dry eye treatment 

Badawi, David 

Clinical ophthalmology (Auckland, NZ) 12 (2018): 683 

This is a prospective, randomised, parallel-group clinical trial. It evaluates the safety and effectiveness of the TearCare system in adult patients with clinically significant dry eye disease. Subjects were randomised to either the TearCare treatment group or a once-a-day warm compress group (WC).

TearCare is an in-office procedure, that is still not commercially available. Its single-use treatment kit consists of four electrothermal devices that are adhesively attached to the tarsal plate of each eyelid. The system delivers a controlled level of thermal energy across the eyelids at a consistent therapeutic temperature of 41°C to 45°C for 12 minutes. The procedure is followed by immediate manual expression of the meibomian glands.

Subjective improvement in symptoms was seen in both the TearCare and WC group. However, the TearCare group showed significantly more improvement in symptoms compared to the WC group. The TearCare group also showed significant improvements in objective measurements, including tear break up time and meibomian gland scores. This improvement was sustained through six months. The WC group showed no improvement in objective measurements.

The prolonged action of TearCare shows a lot of promise for clinical practice. Warm compresses have well-known compliance issues, so a one-off treatment has obvious clinical benefits.

The study has a few limitations: The control group participants were only asked to do warm compresses once a day, as opposed to the standard twice a day recommendation. They were also not instructed to do a massage of the lids following warm compress application. There was also no masking for investigators or subjects. These issues would need to be addressed in a study with a larger sample size to validate the results. Cost effectiveness evaluation as well as a comparison of efficacy with other treatment modalities such as the Lipiflow or intense pulsed Light (IPL) are keenly awaited.

Ryan Mahmoud is a therapeutically qualified optometrist based in Auckland, specialising in dry eye, myopia control and specialty contact lens fitting for corneal ectasias. He owns NVISION Eyecare, where he is principal optometrist.

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