Hand-held optical coherence tomography imaging in children with anterior segment dysgenesis.

In this study, we investigated the potential of hand-held optical coherence tomography (HH-OCT; Fig. 1) to improve diagnosis in anterior segments (AS) by visualizing the anterior and posterior eye structures without general anaesthetic (GA) or sedation. Patients were prospectively recruited from paediatric clinics at the Leicester Royal Infirmary (Table 1). The AS OCT findings allowed diagnosis of iridocorneal endothelial syndrome (ICE) because of endothelium irregularity and the absence of iridocorneal adhesions and embryotoxon. Optical coherence tomography (OCT) at the age of 6 years showed an irregular corneal structure with pericentral corneal thickening on the affected side (Fig. 3). An iridocorneal adhesion began at the thickest part of corneal endothelium and entered into the pupillary part of the iris. Typical contraction folds of the iris were missing (Fig. 3B). The anterior angle in the affected right eye (RE) was open and the iris root appeared thinner (Fig. 3C) than in the left eye (LE) (Fig. 3E) and healthy control (Fig. 3I). On the unaffected side, in the patient with transparent cornea, cup diameter and cup depth were smaller as compared to the control. On OCT (Fig. 4), aniridia was visualized by a missing central part of the iris. A small flat hypoplastic iris stump was detected 360° around the anterior chamber. The patient had clearly defined scleral spurs (Fig. 4B, dotted arrow). Posterior examination showed severe foveal hypoplasia with continuation of retinal nerve fibre layer (RNFL), ganglion cell, inner nuclear and inner plexiform layers in the fovea bilaterally (Fig. 4E). A horizontal tomogram through the centre of the coloboma (Fig. 5E) showed the optic nerve (ON) with a significantly larger distance between the edges of RPE. Optic nerve (ON) cup diameter and depth in the affected eye were larger and nasal and temporal RNFL were thinner than in the fellow/control eye. Foveal pit was also larger in the unaffected eye (Fig. 5F). Anterior OCT assessment enabled the pathology of the cornea to be determined in 4 of 6 patients that was not found clinically. In case 2, OCT findings dictated the necessity of long follow-up of this patient as ICE is slowly progressive condition with extension of the endothelial membrane over the angle and high risk of subsequent glaucoma (Chandran et al. 2015). Lai et al. (2013) described good visualization of the structures of the angle with swept-source OCT and showed that it is possible to use OCT for risk assessment of adult angle-closure glaucoma (Lai et al. 2013; Radhakrishnan & Yarovoy 2014; Sharma et al. 2014). We also found the OCT to be a useful technique in the assessment of the iridocorneal structure in case 6 with PCG, who had a large iridocorneal angle with insertion of the iris root in front of the Schlemm canal on OCT. To our knowledge, there are no data describing angle structure using OCT in patients with PCG. In PCG, patients often have some corneal opacification and Haab's striae (Patil et al. 2015). Abnormal iris insertion with the iris root starting in front of the Schlemm canal was clearly visualized on OCT. This indicates that OCT can be helpful in selecting the best surgical techniques using goniotomy and trabeculotomy if angle structure is preserved and drainage devices in severe angle dysgenesis. Optical coherence tomography (OCT) findings in cases 4 and 5 indicate that subclinical maldevelopment can be present in retinal structures in clinically unaffected eyes. Important clinically relevant information helping diagnosis and management can be obtained non-invasively without GA or sedation with anterior and posterior OCT to assist diagnosis and management of anterior segment dysgenesis (ASDs) especially PCG.