Ultrasound B-scan in pediatric glaucoma

Ruling out secondary causes of glaucoma preoperatively

Pediatric glaucomas can present with various signs most common of which are enlarged eyeballs or buphthalmos and corneal haziness due to epithelial corneal edema. However, a varied number of clinical conditions such as congenital hereditary endothelial dystrophy, mucopolysaccharidosis, and obstetric birth trauma can mimic these features and mislead us to the diagnosis of buphthalmos.^[9-11] Furthermore, there could be associated secondary cause of the increase in intraocular pressure (IOP) causing enlargement of globes which the clinicians need to be aware of and attempt to diagnose before subjecting the child to examination under anesthesia. In one such clinical scenario, a 1-year-old boy was referred to glaucoma services of our tertiary care center, being diagnosed as right eye primary congenital glaucoma based on large eye with high IOP. On performing an ultrasound B-scan, which we routinely perform in all congenital and infantile glaucoma at first presentation, a heterogeneous retinal lesion with calcifications and high reflective echoes in the vitreous was noted which was suggestive of retinoblastoma [Figure 2]. Retinoblastoma, being the most common intraocular malignancy in childhood, can have different types of clinical presentations including leukocoria, strabismus, proptosis, anterior chamber inflammatory signs, and secondary glaucoma.^[10] Although leukocoria and strabismus are usually the most common clinical presentation,^[11] retinoblastoma can also present as buphthalmos with increased corneal diameter and high IOP.^[12,13] Tumor on B-scan presents as a heterogeneous mass arising from the retina, obliterating the vitreous cavity with attachment of the mass to the posterior wall of the globe. These tumors usually demonstrate high internal reflectivity although the amount of reflectivity depends on the amount of calcification. Calcification can be seen in about 50–80% of cases of retinoblastoma^[14,15] but if present confirms the diagnosis. Ultrasound in this case helped in the diagnosis of the condition of the child even before subjecting them to examination under anesthesia. The child was then referred to oculoplastic services and treated appropriately.

Close

Figure 2:

Ultrasound B-scan showing a heterogeneous retinal lesion with calcifications and high reflective echoes in the vitreous suggestive of retinoblastoma (yellow circle).

Export to PPT

Diagnosing associated posterior segment pathologies

Surgical interventions in patients with Sturge-Weber syndrome (SWS) can be associated with increased risks of serious intra and post-operative complications such as choroidal effusions and suprachoroidal hemorrhages. The possibility of these complications increases when SWS is also associated with choroidal hemangioma which is present in around 20–70% of the cases.^[16] Pre-operative ultrasound B-scan in patients with SWS can reveal an underlying choroidal hemangioma in the form of increased choroidal thickness [Figure 3] before taking up any surgical intervention, to alert the surgeon about the possibility of serious and sight-threatening complications during and after surgery, and helps to plan and take appropriate measures to prevent them. Kaushik et al.^[17] reported perioperative use of oral propranolol in a dosage of 2 mg/kg body weight in patients with choroidal hemangiomas to minimize the complications.

Close

Figure 3:

Ultrasound B-scan in a patient with Sturge-Weber syndrome with an underlying choroidal hemangioma in the form of increased choroidal thickness (yellow line).

Export to PPT

Diagnosing and following up on post-operative complications

Choroidal detachments can occur as a sequel to any intraocular surgery more commonly with glaucoma surgeries. They can be serous or hemorrhagic. Clinically, choroidal detachments appear as smooth and dome shaped elevations and can be single or multiple. In children where clinical examination cannot be adequate due to poor cooperation, ultrasound B-scan plays a very important role in not only diagnosing but also helping in differentiating the type of choroidal detachment, and monitoring the response to treatment. Ultrasonographically, choroidal detachments appear as smooth and dome like elevations that usually do not extend beyond the equator. The space behind the membrane is echoluscent in serous choroidal detachments [Figure 4a] or can have multiple moderate to high reflective dot like echoes in case of hemorrhagic choroidal detachments [Figure 4b]. Serial ultrasound examinations can help in detecting the resolution of choroidal detachment and clot lysis in hemorrhagic choroidal detachments which helps in planning the timing for drainage. Change in the contour of the choroidal detachment from convex to concave indicates that the hemorrhage or the detachment is resolving [Figures 5a-d]. It also helps to evaluate associated retinal complications if any.

Close

Figure 4:

(a) Ultrasound B-scan showing smooth and dome like elevations not extending beyond the equator with echoluscent space behind the membrane in serous choroidal detachment (yellow arrow). (b) Multiple moderate-to-high reflective dot like echoes are seen in hemorrhagic choroidal detachment (yellow arrow).

Export to PPT

Close

Figure 5:

(a-d) Series of ultrasound B-scan pictures showing change in the contour of the choroidal detachment from convex to concave indicating that the hemorrhage or the detachment is resolving (yellow arrows).

Export to PPT

Measurement of axial length to monitor progression in eyes with congenital glaucoma

Careful follow-up is very essential for pediatric glaucoma especially post-surgery. As children may not cooperate for IOP measurement at every visit and frequent anesthesia is not possible, detection of progression of glaucoma by means of other cues plays a very important role. Serial axial length measurement by ultrasonography as a means of glaucoma progression detection has been advocated by many authors.^[18-20] The difficulty in monitoring only with IOP is not appropriate as the eyeball can enlarge in size as a response to elevated IOP, which may intern result in normal IOP and miss progression. Any abnormal or abrupt change in the axial length beyond that expected for age should raise the suspicion of elevated IOP.

Post-glaucoma drainage implant surgery follow-up

Lloyd et al.^[21] initially described the echographic evaluation of the filtering blebs post-glaucoma drainage device. As evaluating the filtering blebs postoperatively may not be feasible in every case especially in pediatric glaucoma, ultrasound can aid as a useful adjunct. Fluid around the implant within the bleb is seen on B-scan ultrasound as echoluscent area surrounding the plate which is an echogenic structure [Figure 6]. Although the amount of IOP may not be determined by bleb morphology, the presence of fluid around the implant indicates a functioning tube without any blockage. Serial ultrasonography can help in follow-up of the patient’s post-drainage device implantation. For example, in a 6-year-old kid, who is a case of medically uncontrolled glaucoma in pseudophakia, a non-valved Aurolab Aqueous Drainage device was implanted. At 1-week post-operative visit, ultrasound B-scan detected a hypoechoic bleb devoid of any fluid [Figure 7a]. At week 6 post-operative visit, a large echoluscent fluid filled reservoir with central hyperechogenicity indicating implant surrounded by fluid reservoir was noted confirming that the ligature has opened up [Figure 7b]. At 2-month post-operative visit, the IOP was low at 2 mm Hg and B-scan ultrasonography revealed kissing choroidal detachment [Figure 7c] Due to non-resolving choroidal detachment on serial ultrasonography, the child was taken up for tube ligature. Post-tube ligature B-scan revealed that choroidal detachment was resolved and fluid around the implant was noted [Figure 7d]. Ultrasound B-scan played a very important role at every stage in the diagnosis and follow-up of this complication in this patient.

Close

Figure 6:

Echoluscent area surrounding the plate which is an echogenic structure indicating the fluid around the implant within the bleb along with the horizontal and vertical measurements (green and pink lines) of the bleb on B-scan ultrasound.

Export to PPT

Close

Figure 7:

(a) Ultrasound B-scan showing a hypoechoic bleb devoid of any fluid (yellow circle) seen at 1-week post-operative visit off AADI implantation. (b) Ultrasound B-scan showing a large echoluscent fluid filled reservoir with the central hyperechogenicity (yellow circle) \indicating implant surrounded by fluid reservoir was noted confirming that the ligature has opened up at week 6 post-operative visit. (c) At 2-month post-operative visit, B-scan ultrasonography revealed kissing choroidal detachment. (d) Post-tube ligature B-scan revealed that choroidal detachment was resolved and fluid around the implant was noted.

Export to PPT

Baig et al.^[22] in their retrospective case series evaluated the cases in which B-scan ultrasonography was performed in assessing the glaucoma drainage device patency and function placed in refractory pediatric glaucomas. They found it to be very useful especially in cases where the tube tip was not visualized due to opaque corneas, when IOP was elevated and when the bleb was not visualized. Alonzo et al.^[23] reported a case of 18-month-old girl with primary congenital glaucoma with multiple previous surgeries including Ahmed glaucoma valve implantation who presented with sudden increase in the size of the eye. She was diagnosed with increasing buphthalmos and was started on AGM until B-scan ultrasonography revealed a fluid filled reservoir pushing the globe forward. She subsequently underwent cyst removal with AGV replacement.

To conclude, Ultrasound B-scan is a simple, easily available, and cost-effective modality that has the potential to greatly reduce the number of examinations under anesthesia in children and serve as a useful adjunct to clinical examination.