Cornea: dry, and corneal collagen cross-linking

The new, broader definition of DED, widely promulgated already, was reviewed. According to Watson, one in five people suffer from DED and the results can be serious; significant discomfort, ocular inflammation, infection, and even st cell failure. Psychological effects such as depression, have also been reported, while physical factors are known to exacerbate the condition.The pathogenesis of DED is complex, a fact confirmed by the detailed ‘flow chart’ of the stages, cycles, and contributing factors Watson produced to illustrate its aetiology. DED involves aspects of a circular argument – DED damages the ocular surface, ocular surface disease worsens DED, and around it goes.An association with rosacea is accepted and Watson advised examining a patient in good light initially because its sometimes-subtle facial signs are easily missed. She advised the use of dilute sodium fluorescein stain and no lid manipulation when assessing the tear breakup time with a slit-lamp. However, manipulation is required later when assessing the everted lids for signs of follicles or papillae.{{quote-A:R-W:450-Q: To reduce tear evaporation, Watson suggested blinking fully and frequently, the use of wrap-around sunglasses, avoiding air-conditioning – especially heated environments – and, if necessary, goggles. }}The diagnosis of DED is equally complex but, significantly, tear film osmolality is now a core issue. Importantly, patient questionnaires, such as commonly used McMonnies, the Ocular Surface Disease Index [OSDI], and SPEED, have proved to be most useful, especially in light of the frustrating disconnect between signs and symptoms of the disease.Many objective tests also exist, including TBUT, Schirmer’s #1 test (no topical anaesthetic), vital staining, meibomian gland imaging (Watson uses the Oculus Keratograph 5M) and expressibility, tear film osmolarity (normal 302.2, DED 326.9 mOsm/L), and the presence of biomarkers such as MMP 9.However, impression cytology is no longer undertaken because it can cause a permanent defect at the point of contact. Palliative treatments include unpreserved lubricants (liquids, gels, and ointments), lubricant-lipid combinations, lubricant-osmoprotectant combinations, and simple solutions such as preservative-free saline or balanced salt solution.To reduce tear evaporation, Watson suggested blinking fully and frequently, the use of wrap-around sunglasses, avoiding air-conditioning – especially heated environments – and, if necessary, goggles. Furthermore, she advised the avoidance of allergens, including low-allergy cosmetics, shampoos, etc. and avoiding smoke and pollution sources.If necessary, the complete avoidance of periocular cosmetics was suggested. Other considerations include; the presence of blepharitis, the use of exacerbating systic medications (antihistamines, betablockers, anti-depressants, and anti-Parkinsons agents), and sleep apnoea – all of which are barriers to the optimisation of the patient’s ocular surface.Treatment suggestions, ranging from least to most serious, included; rovable punctal plugs (not intra-canalicular) after any blepharitis has been treated, topical cyclosporin, an altered diet, and the introduction of free fatty acids (e.g., omega-3) supplentation and oral pilocarpine – starting with 5 mg daily, up to a maximum of 4–6x daily.Additionally, if Schirmer Test results are ≤5 mm, or if filamentary keratitis is present, therapeutic soft CL such as silicone hydrogel lenses can be used. More serious treatments are autologous serum drops, and topical steroids, of which unit-dose preservative-free 0.5% prednisolone was mentioned.A new product that has been deed safe by the FDA, but is not yet TGA-approved, is lifitegrast (5%), an inhibitor of T-cell activation and cytokine release. However, some side-effects including blurred vision have been reported already.Suggested ancillary treatments were simple warm compresses or IR or hot-air devices. Beyond those are the IPL and LipiFlow approaches to treating the MGD underlying many cases.In question time, IPL was stated to be possibly destructive, doxycycline was described as a last resort treatment of meibomian glands that produce only toothpaste-like meibum, and the audience was referred to for a overview of rosacea trigger factors.Watson suggested a daily adult omega-3 dosage of 1g of EPA and 0.5g of DHA and half those for children. She also suggested the avoidance of non-steroidal anti-inflammatory (NSAID) drugs after any surgery as they tend to increase inflammation, are expensive, and patients generally do not like th.The use of intraductal probing of the meibomian gland orifices in cases of MGD was the only surgical option covered, but Watson said it required further clinical studies.

The Save Sight Institute’s Professor Stephanie Watson is a corneal and cataract specialist with appointments at the Sydney Eye Hospital, Prince of Wales Hospital, and Sydney Children’s Hospital. As head of the Ocular Repair Group she leads a research program focused on innovative solutions to restore sight and promote ocular health.


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