QUIZ QUESTION MAY 2024

This patient was bothered by a yellow bulge on his right eye that was visible whenever he lifted his upper lid or looked to his left. The bulge was soft and could easily be depressed with a cotton bud. What is it? There are 3-4 important differential diagnoses for a bulge in this area. What are they?

This lesion is soft and is covered by smooth, normal conjunctiva. The diagnosis is therefore orbital fat prolapse. It is caused by a weakness in the orbital septum and tenon’s capsule, allowing orbital fat to migrate anteriorly in the subconjunctival space. It causes no functional problem but can be unsightly for patients.

To treat it, you need to cut open the conjunctiva and resect the prolapsed orbital fat (with care to control bleeding). I then suture the bulbar conjunctiva down onto the posterior sclera, to form a barricade that will prevent orbital fat from ever migrating anteriorly again.

I wanted to share this case because it is a relatively common problem that patients may ask you about. And there are a few important differential diagnoses that must be considered. I’ve explained each of these below.

Dermolipoma 

  • Congenital lesion (present at birth) but often not noticed until adulthood.
  • Due to surface ectoderm cells becoming entrapped within the mesoderm layer of the fetus. The mechanism is very similar to an “orbital dermoid”. 
  • The surface is NOT normal conjunctiva but is keratinised, like skin. Usually has tiny hairs.
  • Solid – cannot be indented with cotton bud.
  • Surgery is best avoided as it can be complicated by severe inflammation and scarring.

Dacryops

  • Fluid-filled cyst caused by an obstructed lacrimal gland duct
  • Translucent. Transilluminates.
  • Often slight bluish colour.
  • Should be resected intact by an orbital surgeon or else it is likely to recur.

Conjunctival lymphoma

  • A lymphoma (tumour of B cell or T cell white blood cells).
  • Can arise in the conjunctiva or can be an extension of an orbital lymphoma.
  • Salmon pink in colour.
  • Will not “bulge” forward, as lymphomas are soft and mould to the globe.
  • Overlying conjunctiva may be normal or abnormal, depending on whether lymphoma cells are invading the conjunctiva.
  • Requires biopsy, orbital and systemic imaging, and involvement of an oncologist.

QUIZ QUESTIONS NOVEMBER 2023

CASE 1

This is a slit lamp transillumination photo of a pseudophakic patient’s RIGHT eye. It shows a fold on their lens capsule. The direction of the fold is from their right temple towards their left cheek.

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The question:

can you predict what this patient will see when they look at a bright light with this eye?

The answer:

I dimmed the lights, held up a pen torch, and asked the patient to draw the pen torch as seen by their RIGHT eye. In doing this, the patient drew their subjective point spread function ie the patient drew the shape that a point source of light cast onto their retina. Their drawing is below (with my annotations).

Patient Drawing right eye streak of light perpendicular to crease fold dr nick andrew sight specialists southport

When looking at a point source of light, the right eye sees a linear streak that is perpendicular to the orientation of the capsule fold.

Their capsule fold runs from their RIGHT temple towards their left cheek, but they see a linear streak that runs from their LEFT temple towards their right cheek.

Discussion:

This is a nice example of what has been named the “Maddox Rod Effect”. That is, a crease on the posterior lens capsule will cause the patient to see a characteristic linear dysphotopsia that is perpendicular to the orientation of their capsular crease. This phenomenon occurs with a single crease, or with several parallel creases. The problem is eradicated by a YAG laser capsulotomy; however, sometimes this isn’t necessary, because the crease often disappears spontaneously as the capsular bag tightens around the lens.

The ”Maddox Rod Effect” is uncommon, but it’s a nice demonstration of optics and it’s worth knowing about. You’ll have patients report it occasionally and the crease is easy to overlook. Both the Maddox Rod Effect and positive pseudophakic dysphotopsia cause patients to see a bright line following cataract surgery. However,  pseudophakic dysphotopsia is seen in the patient’s peripheral vision, whereas the Maddox Rod Effect is seen in their central vision.

Given that awareness of the Maddox Rod Effect is relatively low, for several years I’ve been collecting clinical photographs and patient drawings of my cases. An excellent junior doctor recently presented these at the 2023 RANZCO Congress.

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Dr Malak Habib presenting my collection of cases at RANZCO Congress 2023

QUIZ QUESTIONS NOVEMBER 2023

CASE 2

This patient was referred to me with an inferiorly subluxated IOL.

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After considering all surgical options, I removed their subluxated IOL and sutured a 3-piece lens to the posterior surface of their iris.

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The questions:

  1. Why has this IOL subluxated? 
  2. Why did I decide to suture the lens to their iris? This is not an easy thing to do, therefore why didn’t I fixate the lens to their sclera instead, or implant a large anterior chamber IOL? 

Discussion:

This patient has severe pseudo-exfoliation syndrome, revealed by the florid PXF material at the pupil margin.

This patient’s existing lens wasn’t suitable for suture fixation, therefore I explanted it. Now I need to choose a technique for fixating a new lens into their eye!..

I sutured a new lens to their iris as this approach SPARES their drainage angle and SPARES their conjunctiva. This is important, because given the severe PXF, this eye is at high risk of needing glaucoma filtration surgery in the future. Especially after the stress and steroids of a lens exchange! :)

I want to spare this patient’s conjunctiva, as the patient will likely need it for future glaucoma surgeries.

I can iris-suture an IOL without even touching the patient’s conjunctiva, or their drainage angle. It’s an elegant approach. IOLs fixated to the iris have also been shown to be incredibly well tolerated by the eye, even though it seems counterintuitive.

Below were my alternative IOL options:

  • Fixate the lens to the sclera. I like doing this, but it disturbs the conjunctiva no matter what technique I use.
  • Implant a large anterior chamber IOL. These lenses require a 6mm corneal incision and corneal sutures (with resultant astigmatism). More importantly, they have a high rate of corneal endothelial cell failure and glaucoma. They are easy and fast to implant, but given the complication rate, I only use them in patients who are frail with limited life expectancy.

I’m very fortunate to have been formally trained in the techniques for lens exchanges. This gives me lots of treatment options when planning a patient’s surgery. Given the multitude of surgical techniques, each with its own advantages and limitations, I now find IOL exchanges and secondary IOLs one of the most interesting and complex areas of my work.

QUIZ QUESTION JULY 2023

What abnormality is shown in the RIGHT eye anterior segment OCT?

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The right eye OCT shows angle recession.

This patient reports having blunt trauma to the eye as a young boy.
The right eye has superotemporal iridodialysis and 270 degrees of angle recession.
Fortunately, he does not have elevated eye pressures, glare, or lens subluxation.

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Extensive angle recession confers a LIFELONG risk of elevated eye pressures.

  • Interestingly, eye pressure tends to rise either within 6 months of injury, or after 8-10 years (ie it is bimodal).
  • The tear of the ciliary body does not affect aqueous drainage itself, but the degree of angle recession correlates closely with the hydrodynamic trauma suffered to the trabecular meshwork at the time of the injury.
  • It is generally accepted that a patient needs 180 degrees of angle recession to be at risk of elevated pressures, but this is variable.
  • The mechanism of angle recession is that during blunt trauma, the globe is compressed in an anterior to posterior fashion. This forces aqueous into the angle, expanding the corneoscleral ring and deepening the anterior chamber. This shears through the ciliary muscle causing the iris root to fall posteriorly.
  • Angle recession will always be accompanied by a hyphema, due to rupture of the capillaries within the ciliary muscle. Most patients will also have bleeding from the iris sphincter pupillae muscle (traumatic mydriasis).
  • It’s not too often that you see an anterior segment OCT in angle recession, which is why I wanted to share this case!