Last, and certainly not least, is the unknown role of genetics in determining which child will or will not get aphakic or pseudophakic glaucoma. The aphakic glaucoma does not always seem to segregate in families with heritable cataract, but sometimes it does. The fact that aphakic glaucoma is usually bilateral also supports a genetic theory. Many genes are known to be involved in both cataract and glaucoma, PAX6 being perhaps a paradigm. The complex interaction of gene mutations and polymorphisms continues to be unravelled.
Many of the answers to these questions will lie in research. Some of this work will occur at the basic science bench and the ocular histopathology laboratory. Some will look like that done by Swamy and colleagues (see page 1627)
There is value to retrospective case series. For example, their 20‐year study adds to our recognition that younger age and smaller eyes are at greater risk for the development of glaucoma following cataract surgery. Studies like this will be strongest if the definitions are rigorous. For example. Swamy and co‐workers did not measure corneal diameter and did not measure central corneal thickness, the latter being elevated in many cases of aphakia.4
Ultimately, prospective comparative studies would yield the most power, but they are very hard to do and quite expensive. The challenges are many. Not all aphakic glaucoma is the same; there are early closed angle forms, those induced by postoperative inflammation or steroid use, and the more classic “open angle” late‐onset variety. The late average age of onset requires that the studies be conducted over years, if not decades. The variable onset of cataract, the different morphologies, and the variation of surgical technique (which also evolve over time) necessitate large sample sizes, long‐term funding, and above all investigator persistence and patience.
So what is a paediatric ophthalmologist/cataract surgeon to do? First and foremost, screening must be part of the long term follow‐up care of aphakic children. Their risk for glaucoma appears to be lifelong. I recommend that intraocular pressure be measured at least annually even if sedation or anaesthesia is required. Such procedures also allow for careful measurements, corneal pachymetry and photodocumentation of the optic nerve. Portable techniques will eventually be available to include nerve‐fibre analysis on the supine patient. Normal controls will be essential. If a child is not compliant with awake tonometry, virtually every outpatient visit should include proxy measurements for glaucoma such as refraction (or over refraction) to look for increasing axial length, slit‐lamp examination looking for corneal oedema and, if possible, a view of the optic nerve. These can often be accomplished outside the academic centres with a bit of patience and without pharmacological dilation of the pupil. I recommend outpatient visits no less than every 6 months.
Second, we must continue research not only into the pathophysiological basis of aphakic glaucoma but also into the most effective ways to screen, measure, and treat the disease. Although we should continue retrospective studies, prospective randomised trials with rigorous inclusion criteria and detailed data collection offer the best hope but at the highest cost. Multicentre collaborative approaches in partnership with academic facilities where these children tend to congregate and countries such as India and Saudi Arabia, where the incidence may be higher due to the higher incidence of cataract, will be essential. It may be many years before this story has an ending, but the wait will well be worth it all.