Are you a veterinary professional looking for valuable insights into the management of common corneal disorders? Look no further! In our recent webinar, titled "Ophthalmology: 'Get on the Case' An Interactive Case-Based Approach to the Management of a Range of Common Corneal Disorders," Dr. Emma Hancox addressed several pressing questions posed by participants. Here's a recap of the questions asked and Dr. Hancox's expert responses:

1. How far apart do you space antibiotic from Remend gel?

• Dr. Hancox advised applying the antibiotic before the Remend Corneal gel. The duration between applications depends on the antibiotic formulation, recommending 5-10 minutes for drops and at least 30 minutes for ointments.

2. Chloramphenicol 1% ointment vs. 0.5% drops?

• The 1% ointment is similar to the 0.5% drops but requires less frequent application due to its consistency and concentration. Dr. Hancox recommended applying drops 3-4 times daily and ointment twice daily for superficial ulcers.

• However, consideration should also be given to timing between drops - if you are using drops, then 5-10 minutes between is sufficient, but with an ointment, then ideally this is either applied last and/or at least 30 minutes is left before appyling anything else.

• Finally, it is also worth noting that an ointment is not ideal when it comes to deep/stromal/melting ulcers as the consistuents of an ointment can be associated with ganulomatous uveitis in these cases and often they require very frequent application e.g up to every 30-60 minutes which an ointment is not ideal for. In Dr. Hancox personal opinion, if she were to only stock one, her preference would be the drops.

3. Ideal concentration and molecular weight for HA products?

• Dr. Hancox suggested a concentration of HA above 0.3% and high molecular weight (>1.7MDa) for optimal effectiveness. She highlighted the Remend products, known for their high molecular weight.

4. Antibiotics for corneal ulcers apart from gentamycin?

• Dr. Hancox discouraged the use of topical antibiotics subconjunctivally or intra-palpebrally due to unestablished dosage and concentration.

5. Does acetylcysteine given parenterally or orally have the same effect as drops?

• Dr. Hancox clarified that oral or parenteral acetylcysteine does not yield the same effect as drops due to differences in tear film concentration.

6. Use of Stromease alongside Remend gel and antibiotics?

• Stromease is recommended alongside antibiotics and Remend gel, especially in at-risk breeds or advanced ulcer cases.

7. Usage of phenol for medical treatment?

• Unfortunately, the use of phenol for chemical cautery of SCCED ulcers is no longer recommended, although she appreciate that this method is still popular. Phenol carries a high risk of corneal melting, espeically if used in excessive amounts or not flushed properly afterwards. To her knowledge, they aren't any papers that provide a "success rate" with this method and information is rather anecdotal. Certainly, diamond burr or grid keratotomies are preferred due to the lower risk nature and improved control the clinician has.

8. References for RGTAs and clarification on Remend dry eye drops concentration?

• The Remend Corneal Gel has always been 0.75% HA. The Remend Dry Eye Lubricant drops are 0.4%

• With regards to the evidence for RGTAs, there many papers available online, it is often worth searching for RGTA and/or Cacicol which is the trade name of the human version of Clerapliq as well. However, a couple of the most interesting include: Martinez, Jessica A., Franck Chiappini, and Denis Barritault. "Case Reports for Topical Treatment of Corneal Ulcers with a New Matrix Therapy Agent or RGTA® in Dogs." Veterinary Sciences 6.4 (2019): 103, and also Brignole-Baudouin, F., et al. "RGTA-based matrix therapy in severe experimental corneal lesions: safety and efficacy studies." Journal francais d'ophtalmologie 36.9 (2013): 740-747. Finally, this paper goes more in depth to the mode of action of RGTAs which can be useful Barritault, Denis, et al. "RGTA® or ReGeneraTing Agents mimic heparan sulfate in regenerative medicine: from concept to curing patients." Glycoconjugate journal 34 (2017): 325-338.

9. Does chloramphenicol cause stinging upon application?

• Chloramphenicol stinging, in the human datasheet, mild stinging on application is listed as an uncommon side effect, however, due to the unlicenced nature in animals we do not have similar frequency reports in dogs or cats. However, in her time using Chloramphenicol drops, she have had no patients reacting to these drops and similarly it does not seem to be listed as an issue within the veterinary literature. That said, there is always some individual variability in this, and often patient's with superficial ulcers can react to any drop being applied due to exposed and damaged nerve endings, this is why she would always recommend some sort of analgesia as well.

10. Concerns about dry eye treatment refusal by owners and euthanasia?

• Regarding a refusal of dry eye treatment and possible euthanasia, this is a really difficult question to answer and will be very case/patient/owner dependant. It is interesting, that in one of the studies for the Remend Dry Eye drops, the cohort of patient's chosen were those who were NOT on immunemodulators e.g Optimmune and only receiving topical lubrication. In this setting, Remend did help to ameliorate some of the signs seen and the owners were happy with the results. However, this is not something that we recommend. I think euthanasia or even enucleation could be considered, particularly in the severe cases where topical lubrication and other interventions are not helping to relieve their symptoms - at the end of the day, Dry Eye is very uncomfortable for the patient, and leaves them at risk of further eye problems.

11. Efficacy of rose water for dry eyes and opportunities for online lectures?

• Rose water or rose extract is anecdotally used for soothing irritated eyes and reportedly has mild antiseptic and antiinflammatory properties - we actually have rose extract in our product Ocryl which is a daily cleaner, ideal for these ongoing Dry Eye patients. Whilst rose extract will do no harm, the benefits however are only limited to anecdotal reports with limited robust efficacy studies at present. Therefore, we can only recommend it as an adjunct to treatment and to help with daily hygiene, rather than a replacement for medicated drops.

• With regards to an online lecture for DVM students, please do email Dr Hancox.

12. Indications for oral doxycycline in corneal ulcer cases and alternatives for local anesthetics?

• Oral doxycycline is somewhat popular for corneal ulcers although current published evidence is somewhat lacking. The idea is that tetracyclines can exert an anti-collagenase effect, similar to that described for Stromease/serum in the management of melting or stromal ulcers. So in that sense, if you are using Stromease, there is no benefit to using oral doxycycline as well. The issue is that, unless there is active neovascularisation of the ulcer essentially delivering the oral doxycycline to the area, the tear film concentrations will be too low to be beneficical from oral dosing. Further to this, we need to be judicial in our perscribing of oral antibiotics and, when there is a licenced altnerative anti-collagenase, she don't see a need for oral doxycycline for corneal ulcers. With regards to local anaesthetics, alternatives can include tetracaine and oxybuprociane.

If you missed the webinar, you can catch it on demand HERE, free to watch thanks to TVM. For further inquiries, feel free to contact Dr. Emma Hancox at [email protected].

Stay tuned for more insightful webinars and updates in the field of veterinary ophthalmology!