Optical coherence tomography of the Ex-PRESS miniature glaucoma implant

Imaging of filtering blebs after implantation of the Ex-PRESS shunt with the use of the Visante optical coherence tomography

AIM

To analyze the features of the filtering blebs following implantation of the Ex-PRESS glaucoma device (model P-50) with the aid of the Visante anterior segment optical coherence tomography (AS-OCT).

METHODS

Five patients with open angle glaucomas were included in the study. They all underwent implantation of the Ex-PRESS device under a scleral flap. The surgical procedure was augmented with the use of mitomycin C subconjunctivally. The filtering blebs were analyzed with the Visante AS-OCT with the scans taken along the axis of the implantation of the glaucoma device.

RESULTS

All filtering blebs were graded as diffuse functioning. The morphological characteristics of the blebs were similar to those of the trabeculectomy. However the use of the Ex-PRESS implant tend to form a characteristic episcleral lake at the site of the plate of the implant.

CONCLUSION

The use of the Ex-PRESS implant produces filtering blebs similar to those of the trabeculectomy with the formation of a characteristic episcleral lake at the site of the plate of the implant.

Ultrasound evaluation of glaucoma drainage devices in children

This study evaluated B-scan ultrasound as a technique for assessing glaucoma drainage device (GDD) patency/function in refractory pediatric glaucoma. We retrospectively evaluated 70 eyes of 52 patients after Ahmed (n = 40 eyes), Baerveldt (n = 27 eyes) and Molteno (n = 5 eyes) GDD implantation; 2 eyes each had 2 GDDs. Median age was 6.5 years. Glaucoma diagnoses included primary congenital glaucoma (n = 19) and secondary glaucoma associated with aphakia (n = 16), aniridia (n = 5), Peters anomaly (n = 3), uveitis (n = 2), and other conditions (n = 7). B-scan ultrasound evaluation proved helpful to clinical assessment when the GDD tube was not seen because of opaque corneas (n = 20 eyes), the bleb was not visualized (n = 21 eyes), or IOP was elevated (n = 28 eyes). Ultrasound findings suggesting a nonpatent or malfunctioning GDD were further confirmed by subsequent intraoperative bleb needling (n = 2 eyes) and GDD revision (n = 7 eyes). B-scan ultrasound evaluation can serve as a useful adjunct in evaluating GDD patency/function in selected eyes with refractory pediatric glaucoma and may aid in clinical management.

Anterior segment optical coherence tomography imaging of conjunctival filtering blebs after glaucoma surgery

Time domain (TD) and spectral domain (SD) optical coherence tomography (OCT) are cross-sectional, noncontact, high-resolution diagnostic modalities for posterior and anterior segment (AS) imaging. The AS-OCT provides tomographic imaging of the cornea, iris, lens, and anterior chamber (AC) angle in several ophthalmic diseases. In glaucoma, AS-OCT is utilized to evaluate the morphology of AS structures involved in the pathogenesis of the disease, to obtain morphometric measures of the AC, to evaluate the suitability for laser or surgical approaches, and to assess modifications after treatment. In patients undergoing surgery, AS-OCT is crucial in the evaluation of the filtering bleb functionality, permitting a combined qualitative and quantitative analysis. In this field, AS-OCT may help clinicians in distinguishing between functioning and nonfunctioning blebs by classifying their macroscopic morphology, describing bleb-wall features, bleb cavity, and scleral opening. This information is critical in recognizing signs of filtration failure earlier than the clinical approach and in planning the appropriate timing for management procedures in failing blebs. In this review, we summarize the applications of AS-OCT in the conjunctival bleb assessment.

Application of anterior segment optical coherence tomography in glaucoma

Optical coherence tomography (OCT) is a cross-sectional, three-dimensional, high-resolution imaging modality that uses low coherence interferometry to achieve axial resolution in the range of 3-20 μm. Two OCT platforms have been developed: time domain (TD-OCT) and spectral (or Fourier) domain (SD/FD-OCT). Visante anterior segment OCT (Carl Zeiss Meditec) is a TD-OCT widely used for anterior segment imaging. The SD-OCT systems with both posterior and anterior segment imaging capabilities include the RTVue, iVue (Optovue), the Cirrus (Carl Zeiss Meditec), and the Spectralis (Heidelberg Engineering, Inc.). Each of the SD-OCTs has a wavelength in the range of 820-879 nm. Anterior segment OCT is a non-contact method providing high resolution tomographic cross-sectional imaging of anterior segment structures. Anterior segment OCT provides qualitative and quantitative assessment of the anterior segment structures important to the pathogenesis and the anatomical variations of glaucoma, and the approach to and success of treatment. We summarize the clinical applications of anterior segment OCT in glaucoma.

Fourier Domain Optical Coherence Tomography integrated into a slit lamp; a novel technique combining anterior and posterior segment OCT

PURPOSE

Fourier Domain Optical Coherence Tomography (FD-OCT) provides high resolution cross-sectional images of the retina and the anterior segment. It has become an important tool in ophthalmology in the examination, diagnosis, and treatment of important and common diseases. Present OCT imaging systems are stand-alone devices. The aim of this paper is to show the quality of images made with a prototype of a Fourier Domain (FD-) OCT imaging system (SLSCAN-1) integrated into a slit lamp.

METHODS

Different representative pathologies of the posterior and anterior segment were observed with the slit lamp and simultaneously scanned with a prototype of the slit lamp-integrated FD-OCT system. The clinical interpretation of posterior segment images made with the prototype were compared to those obtained with a stand-alone FD-system (3D-OCT-1000 Mark II, Topcon).

RESULTS

Images made with the slit lamp-integrated FD-OCT were of sufficient quality to allow for a correct interpretation of the observed pathological conditions. Conclusions based on the images of the posterior segment of the prototype were identical to the conclusions based on the images of a stand-alone FD-system (3D-OCT-1000 Mark II, Topcon). In addition to the images of the posterior segment, images could be made of the anterior segment. The OCT system did not interfere with the normal functionality of the slit lamp.

CONCLUSION

The slit lamp-integrated FD-OCT system provided high quality images of both the anterior and the posterior segment. Scans made with the slit lamp-integrated FD-OCT system could be of use in clinical practice.