By: Annabel Groot, resident ophthalmologist
Starting in 2013, we collected a large amount of data on 58 children with congenital anophthalmia and microphthalmia during outpatient visits at AmsterdamUMC (formerly VUmc). A large portion of that data has now been analyzed: vision, eye abnormalities, other physical abnormalities, genetic background, and changes in eye measurements over the years. We will briefly summarize the key findings.
Features
• Most of the children had one affected eye, but 1 in 4 had it in both eyes. Microphthalmia is more common than anophthalmia: in the group with unilateral affected eyes, approximately 75% had microphthalmia and 25% had anophthalmia.
• In the monocular group, 9 out of 10 children have good vision according to WHO standards. One in 10, however, does not see well: this is due to brain abnormalities, strabismus, or nystagmus (shaking eyes). This contrasts with the bilateral group, where 93% are visually impaired or blind.
• 50% also have abnormalities in other organs. These can range from harmless to more serious. Examples include a small extra ear, abnormalities of the brain or heart, or slower mental or motor development compared to other children. It is therefore important to have these children examined by a geneticist or pediatrician as well.
• Of the 47 blood samples analyzed, a genetic cause was identified in 12 children. The most common was the SOX2 mutation, which leads to bilateral anophthalmia.
Serious characteristics
• Compared to the other normal eye, eyes with anophthalmia and severe microphthalmia (in which there is barely any eye structure) have an axial length of only 15% (compared to the normal eye).
– a horizontal palpebral fissure of only 58% (compared to the normal side).• There was a strong correlation between the horizontal palpebral fissure and the size of the eye. The smaller the eye, the smaller the palpebral fissure. And the larger the eye, the larger the palpebral fissure. In cases of mild microphthalmia, the difference compared to the normal side is therefore often not that great.
• Some eyes continue to grow despite their abnormality: this was the case for about half of the eyes. This can influence treatment decisions: an eye that stops growing is more likely to be considered for treatment.
• Based on these data, unilateral anophthalmia/microphthalmia is considered severe if the affected eye is 0–45% the size of the normal eye, moderate at 45–75%, and mild at >75%.
• We have strived to treat severely affected children as quickly as possible (within a few weeks) using conformers that mimic the growth of a normal eye. In our experience, treatment for moderate cases is often advisable for symmetry, and treatment was typically started within a few months. For mild cases, treatment may be performed for cosmetic reasons, but this is not always necessary and can potentially be done at a later age.
• In cases of bilateral anophthalmia/microphthalmia, there is no “normal” side, and treatment with conformers can be considered once it has been ruled out that the eye has any vision. Symmetry is then determined based on the larger side.
With these results, we have established a rough classification system that allows us to distinguish between children who require immediate treatment and those for whom treatment is less urgent. This requires measuring the horizontal palpebral fissure and the size of both eyes. It is important that, in addition to the ophthalmologist and ocularist, other specialists be involved as well: among others, a clinical geneticist or pediatrician to assess other abnormalities, and a low-vision specialist if vision is insufficient.
Thank you to the parents and children for their permission
We would like to express our sincere thanks to all parents and children for their permission to use the data anonymously. This allows us to share our experiences and knowledge with the rest of the world, and conversely, to learn from specialists abroad who, in turn, share their experiences with us. The research is still ongoing and will focus in the coming period on, among other things, the development of the eye socket and the analysis of the conformers used, conducted by ocularist Jelmer Remmers.
