Clive’s Corner Potpourri

Potpourri

1. Face mask-associated ocular issues

Some face masks interfere with the airflow around the eyes. If the top of the mask is not sealed properly, expired air is diverted upwards towards the eyes. If the mask is sealed but the seal is too high up on the cheeks, interference with lower-lid function can occur. This can all lead to ocular irritation, dryness and even keratopathy.

Patients should be instructed to take breaks from mask wear, use lubricants, and do blink exercises. Blink exercises are performed by pressing the index fingers just outside of the lateral canthi and then consciously blinking ten times without feeling muscle contraction with the finger.

It has also been suggested that face masks can predispose patients to ocular infection and postoperative or post-intravitreal injection endophthalmitis by redirecting her thanking me profusely for this advice. She had been to a physiotherapist who, over a one-month period, had treated her back and neck. This is what she said on the email: ‘All the ocular symptoms were relieved gradually as the spasm was worked out of my back and neck.’ airflow, together with microorganisms, towards the eyes.

Face masks can also cause artifacts on visual field testing either by directly blocking a part of the visual field or by fogging up the lens.

I also instruct patients having YAG to remove the mask or to tape it down at the top as it often causes fogging of the YAG contact lens.

2. Neck problems

Several months ago, I saw a patient (who is an optometrist with a PhD) with ocular discomfort and a foreign body feeling in the one eye. It had been going on for a few months. She had seen two other optometrists who could find no FB and nothing wrong. She was given Alrex drops plus lubricants, which helped little. I also could find no FB and no cause for the irritation. I then asked her about her neck, and she did indeed have neck spasms.

Now it is well known that neck spasms and other neck abnormalities can cause ocular pain (especially retrobulbar pain). But I never thought that ocular discomfort and FB feeling could be caused by neck issues. However, as I had no other treatment to offer her, I advised her to see her GP about her neck problem.

A few days ago, I received an email from her thanking me profusely for this advice. She had been to a physiotherapist who, over a one-month period, had treated her back and neck. This is what she said on the email: ‘All the ocular symptoms were relieved gradually as the spasm was worked out of my back and neck.’

3. Reverse pupil block

Broke the reverse pupil block ? IOL in the sulcus? Watch out for reverse pupil block (RPB). The mechanism for RPB is thought to be the passing of aqueous from the ciliary body via the choroid and angle into the AC. The IOL blocks the aqueous from going back through the pupil and pressure builds up in the AC. Another mechanism is thought to be the forming of a flap valve between the IOL and the posterior iris. This one-way valve lets fluid through anteriorly but blocks its flow posteriorly.

You can suspect RPB at the slit lamp if you see a deep AC, concavity of the iris, and iris transillumination defects.

Regardless of the mechanism, a peripheral iridotomy is usually curative.

RPB can also lead to pigment dispersion glaucoma and the UGH syndrome. Making a PI with the YAG laser or surgically during phaco should help to avoid these nasty consequences. RPB is more common in myopic eyes and post-vitrectomised eyes. Therefore, a surgical PI should definitely be cut if a sulcus IOL is to be placed in these eyes.

4. Azomid

Be careful when prescribing Azomid tablets! Azomid is the generic for Diamox – but it’s also the generic for the antibiotic azithromycin.

This should never have been allowed to happen and I don’t think that azithromycin is available as Azomid in South Africa. But if you google Azomid, you will find that it could refer to either one. To add to the ambiguity, the dosages are the same: 250 mg tablets.

Diamox has not been available in SA for several years now. Therefore, if I want to bring a very high pressure down rapidly I prescribe Azomid. But I always write ‘generic of Diamox’ in brackets just in case the pharmacist googles Azomid and thinks it’s the antibiotic.

Talking about rapid lowering of IOP, Combigan is probably the most efficient drop for this. Combigan is an alpha agonist (brimonidine) plus a beta blocker (Timolol). A prostaglandin analogue is great for long-term IOP control but takes several weeks to work.

5. Flu can cause neuroophthalmological anomalies

Covid-19 can cause conjunctivitis, retinitis and neuro-ophthalmological anomalies. But so can the common flu. The Canadian Journal of Ophthalmology March 2021 reported a case of a 38-year-old woman who presented with new onset left ptosis plus diplopia. Two days prior she had nasal congestion, cough, fever and myalgias. Examination revealed a pupil-sparing third nerve palsy. MRI showed a mild enlargement of the left oculomotor nerve. Nasopharyngeal swab was positive for influenza A. She was treated conservatively, and symptoms resolved within two weeks. They did not mention if a Covid PCR test was done on the nasopharyngeal swab.

6. Removing a corneal FB using a hair

The other day I saw a young man with a metallic corneal foreign body after grinding without safety goggles. He told me that he had tried to remove it himself but failed. I asked him how he tried to remove it. He said ‘with a hair’ ! He plucked a hair from his head and, holding it like dental floss, he rubbed the FB on the cornea in an effort to dislodge it. When he saw the surprised look on my face he explained that this was a common method for removing ocular FBs among welders, grinders and boilermakers. I confessed that I had never heard of this and that he was teaching me something new.

Photo credit: Syamsul Alam / Shutterstock.com

7. Lasik interface problems

I retired from Lasik/PRK surgery about two years ago. My stress levels took a big turn for the better after that. But even if you do not perform keratorefractive surgery, you obviously have to be familiar with ocular problems that can occur in these patients related to that surgery.

One of the issues that all ophthalmologists need to be aware of, is Lasik interface fluid collection. Years after Lasik, fluid can collect in the interface due to trauma, inflammation, increased IOP or endothelial insufficiency. Increased IOP may be missed in these patients because if you measure over the central cornea, the fluid may give a falsely low reading. Therefore, in these patients you should measure the IOP with an Icare or Tonopen on the corneal periphery.

Another issue to be aware of is that corneal epithelial healing may be delayed or problematic in these patients. This is because surface healing may be slower due to flap denervation and possible neurotrophic keratopathy. If cataract, glaucoma or retinal surgery is performed, extra care needs to be taken not to disturb the epithelium. Some vitreoretinal surgeons have a low threshold for debriding the corneal epithelium to improve intraoperative visualisation, so beware if the patient has had previous Lasik or PRK.

For further discussion and references on any of these topics, please email me at clivenovis@mweb.co.za. 

Dr Clive Novis Dip Optom, MBBCh(Wits), MMed(Wits), FCS(Ophth) clivenovis@mweb.co.za