Infrared angiography of the anterior ocular segment

Optical coherence tomography angiography application to pigmented iris: Could a new index quantify blood flow?

PURPOSE

To assess the blood flow and vascular visibility of irises in relation to pigmentation and pupil size, using an anterior segment optical coherence tomography angiography (OCTA).

MATERIALS AND METHODS

This is a cross-sectional study. OCTA images were acquired in the nasal and temporal quadrants from a cohort of 30 healthy subjects in photopic (miosis) and scotopic (mydriasis) conditions. Patients were divided according to iris color (less pigmented: group L vs more pigmented: group D). Vascular parameters (vessel density (VD), vessel length density (VLD), fractal dimension (FD)) were applied and compared among groups L and D, location and different pupil status. A novel vascular index called Luminance Index (LI) was developed and applied in order to quantify vascular flow and evaluate its variation in photopic and scotopic conditions. Multivariable analyses were performed to evaluate possible predictors of VD and LI.

RESULTS

No differences were found for all vascular measurements (VD, VDL, FD, LI) between nasal and temporal quadrants. All vascular measurements were higher in group L than in group D (p < 0.05), except for LI and FD in photopic condition. In group L, all vascular parameters increased (p < 0.001) after dark adaptation. In group D, only LI increased after dark adaptation (p < 0.001). Pigmentation and iris thickness were significantly associated with VD in scotopic and photopic conditions, and with LI only in scotopic condition.

CONCLUSIONS

Pigmentation still remains a major issue for vascular visibility. Quantitative and qualitative vascular changes follow pupil size variation. LI could be a new surrogate to quantify blood flow.

Anterior Segment Scleral Fluorescein Angiography in the Evaluation of Ciliary Body Neoplasm: Two Case Reports

Introduction

Anterior segment tumors can be difficult to detect until tumor growth is substantial enough to cause local signs or symptoms. Earlier detection may result in improved outcomes, particularly the ability to option for globe-conserving therapy. Multiple diagnostic modalities such as ultrasound or optical coherence tomography exist to aid for earlier detection of ciliary body tumors, but they also have limitations. Here we describe the potential for scleral angiography as an adjunctive modality to assist in evaluating anterior segment ciliary body tumors.

Case Presentations

A 61-year-old Caucasian male and a 57-year-old Hispanic female presented for ciliary body tumor evaluation. The Caucasian male notably had abnormal scleral, episcleral, and conjunctival vessels in the affected eye. Scleral angiography was performed in both cases with the abnormal vasculature highlighted in the Caucasian male. The Hispanic female did not demonstrate abnormal scleral angiographic patterns. Notably, the Caucasian male also had regions of abnormal scleral angiography arising in locations of otherwise normal appearing sclera. Both patients had the affected eyes enucleated. Histology of the enucleated eyes demonstrated a ciliary body melanoma in the Caucasian male associated with abnormal vascular and tumor infiltration of the scleral bed. The Hispanic female had a pigmented ciliary body adenoma without involvement of the scleral bed.

Conclusion

With limited sample size, scleral angiography has the potential to detect abnormal scleral vascular patterns in otherwise normal appearing sclera in cases of ciliary body tumor with scleral vascular invasion.

Fluorescein gonioangiography of the normal canine eye using a dSLR camera adaptor

The purpose of this study was to describe fluorescein gonioangiography (FGA) of the normal canine eye using a digital single lens reflex (dSLR) camera adaptor. Dogs were anesthetized using intravenous propofol. Imaging was performed using a Lovac Barkan goniolens, dSLR camera, dSLR camera adaptor, camera lens, and accessory flash. Twelve dogs with a mean age of 2.0 +/- 0.8 years were imaged. No characteristic angiographic phases were observed. Leakage from the peri-limbal capillary network was a common finding and occurred 7.7 +/- 2.2 s post injection in 9 (75%) dogs. In 3 (25%) dogs, filling of the circumferential ciliary artery was observed 10.3 +/- 2.8 s post injection. Dye leakage within the iris base and into the aqueous humor was demonstrated in 4 (33%) and 6 dogs (50%) respectively. No adverse events were noted. This study demonstrates FGA findings in normal canine eyes using a cost effective dSLR camera adaptor.

Anterior segment angiography of the normal canine eye: a comparison between indocyanine green and sodium fluorescein

The objective of this study was to assess and compare indocyanine green (IG) and sodium fluorescein (SF) angiographic findings in the normal canine anterior segment using a digital single lens reflex (dSLR) camera adaptor. Images were obtained from 10 brown-eyed Beagles, free of ocular and systemic disease. All animals received butorphanol (0.2 mg/kg IM), maropitant citrate (1.0 mg/kg SC) and diphenhydramine (2.0 mg/kg SC) 20 min prior to propofol (4 mg/kg IV bolus, 0.2 mg/kg/min continuous rate infusion). Standard color imaging was performed prior to the administration of 0.25% IG (1 mg/kg IV). Imaging was performed using a full spectrum dSLR camera, dSLR camera adaptor, camera lens (Canon 60 mm f/2.8 Macro) and an accessory flash. Images were obtained at a rate of 1/s immediately following IG bolus for 30 s, then at 1, 2, 3, 4 and 5 min. Ten minutes later, 10% SF (20 mg/kg IV) was administered. Imaging was repeated using the same adaptor system and imaging sequence protocol. Arterial, capillary and venous phases were identified during anterior segment IG angiography (ASIGA) and their time sequences were recorded. ASIGA offered improved visualization of the iris vasculature in heavily pigmented eyes compared to anterior segment SF angiography (ASSFA), since visualization of the vascular pattern during ASSFA was not possible due to pigment masking. Leakage of SF was noted in a total of six eyes. The use of IG and SF was not associated with any observed adverse events. The adaptor described here provides a cost-effective alternative to existing imaging systems.

Novel molecular imaging approach for subclinical detection of iritis and evaluation of therapeutic success

There is an urgent need for early diagnosis in medicine, whereupon effective treatments could prevent irreversible tissue damage. Acute anterior chamber inflammation is the most common form of uveitis and a major cause of vision loss. The proximity of the iris vasculature to the light-permeable cornea and its involvement in ocular inflammation make it an ideal target for noninvasive molecular imaging. To accomplish this, carboxylated fluorescent microspheres (MSs) were conjugated with recombinant P-selectin glycoprotein ligand-1 and systemically injected in endotoxin-induced uveitic animals. MS adhesion in the microcirculation of the anterior and posterior chamber was visualized by intravital microscopy and scanning laser ophthalmoscopy. In iritic animals, significantly higher numbers of recombinant P-selectin glycoprotein ligand-1-conjugated MSs adhered to the endothelium (P = 0.03) matching the increase in leukocyte adhesion. Conjugated MSs specifically interacted with firmly adhering leukocytes, allowing quantification of the endogenous immune response. Topical eye drop treatment with dexamethasone (P < 0.01) or cyclosporine A (P < 0.01) significantly lowered MS adhesion in iris vessels. Surprisingly, topical dexamethasone significantly reduced MS interaction in the fundus vessels (P < 0.01), while cyclosporine A did not. In vivo MS accumulation preceded clinical signs of anterior uveitis and leukocyte adhesion in iris vasculature. This work introduces noninvasive subclinical detection of endothelial injury in the iris vasculature, providing a unique opportunity for quantifying vascular injury and immune response in vivo.

A case of primary B-cell type non-Hodgkin lymphoma originating in the iris

PURPOSE

To report a case of primary malignant B-cell type non-Hodgkin lymphoma originating in the iris.

DESIGN

Interventional case report.

METHODS

An 83-year-old woman presented with anterior uveitis resulting from primary malignant lymphoma in the iris. Ultrasound biomicroscopy and indocyanine green angiography using a scanning laser ophthalmoscope showed abnormalities in the iris. Diagnostic biopsy of the iris revealed B-cell type non-Hodgkin lymphoma.

RESULT

The patient was treated with radiotherapy, and the tumorous lesion resolved.

CONCLUSION

Primary lymphoma localized in the iris only is rare. In this case, diagnostic biopsy and radiotherapy of the iris lymphoma provided good results.

Indocyanine green angiography in chorioretinal diseases: indications and interpretation: an evidence-based update

TOPIC/PURPOSE: To assess the clinical usefulness and relevance of indocyanine green angiography (ICG) in the investigation of chorioretinal disorders and assess specifically in what conditions it may add useful information to that obtained using standard fluorescein angiography.

CLINICAL RELEVANCE

Many publications on ICG have appeared in recent years touting its use in ophthalmology. These publications have led to increasing use of this technique and to its application in numerous retinal diseases in which the fluorescein angiographic findings have been thoroughly described.

METHODS/LITERATURE REVIEWED

During this systematic literature review, we identified and reviewed a total of 376 articles, from among which we selected 92 that we considered most relevant to our purpose of evaluating published evidence as to the efficacy of ICG. We excluded many articles with weak study designs and those that simply duplicated previously published information. Our literature search used PubMed and was confined to articles in English or that included an English abstract.

RESULTS

Our systematic review suggests that ICG has relatively few specific indications for use as justified by previously published peer-reviewed studies. In keeping with the requirements for this Journal's evidence-based articles, we have divided our clinical recommendations for the use of ICG into three categories: (A) strongly recommended and supported by strong evidence; (B) recommended with moderately strong supporting evidence; (C) not recommended at present because supported only by anecdotal or group consensus evidence. We highly recommended ICG for (1) identification of polypoidal choroidal vasculopathy, (2) occult choroidal neovascularization, (3) neovascularization associated with pigment epithelial detachments, and (4) recurrent choroidal neovascular membranes. These are all conditions in which ICG contributes to the identification of lesions that may be treatable. We recommend ICG with some enthusiasm for identifying feeder vessels in age-related macular degeneration, choroidal neovascular membranes, chronic central serous retinopathy, multiple evanescent white dot syndrome, vasculitis, acute multifocal placoid pigment epitheliopathy, Vogt-Koyanagi-Harada syndrome, macular lesions associated with angioid streaks, and birdshot retinopathy. In all these conditions, ICG may help establish a diagnosis and provide some useful guidance for therapy. At present, we do not recommend ICG for scleritis and posterior scleritis, drusen differentiation, Behçet's disease, or sarcoidosis, because it has not been demonstrated to add useful clinical information.

CONCLUSIONS

ICG, although now a well established technique, has clear advantage over fluorescein angiography in relatively few chorioretinal disorders. It has, however, contributed to the understanding of pathologic processes in many ocular diseases. As yet, no published randomized controlled clinical trials show any benefit to the use of ICG in the management of any specific ocular disease.

Anterior segment indocyanine green angiography in pterygium surgery with conjunctival autograft transplantation

PURPOSE

To assess indocyanine green angiography (ICGA) as a method for monitoring autograft perfusion after pterygium excision with limbal-conjunctival autograft transplantation (LCAT) and to compare ICGA with anterior segment fluorescein angiography (ASFA).

DESIGN

Nonrandomized prospective interventional case series.

METHODS

Twelve eyes of 11 patients with primary pterygium treated by excision and limbal-conjunctival autograft transplantation were studied in a clinical practice. Anterior segment fluorescein angiography and ICGA findings for autograft vascularization after pterygium surgery were compared in 12 eyes of the 11 patients. Graft perfusion was monitored for 1 month with ASFA and ICGA, on days 1,7, and 30 post-surgery.

RESULTS

With ASFA no graft perfusion was observed by postoperative day 30; only five grafts were isofluorescent with some vascularization, while the remaining seven grafts were hypofluorescent without any vascularization. In contrast, ICGA showed that, on postoperative day 1, all 12 grafts were hypofluorescent with multiple hyperfluorescent foci at the graft margin in the late phase and that, by postoperative day 7, 10 grafts were hypofluorescent and appeared to be perfused, originating from the episcleral vascular bed. On day 30, ICGA demonstrated isofluorescent grafts in 10 eyes with some conjunctival and episcleral vascular patterns on the graft itself, including the conjunctiva adjacent to the graft. By this stage, perfusion of the graft was complete.

CONCLUSION

Indocyanine green angiography is useful for monitoring graft perfusion after LCAT in pterygium surgery. Further studies are needed to identify the implications of graft perfusion for therapy following LCAT in patients with pterygium.

Evidence-based recommendations for the diagnosis and treatment of neovascular glaucoma

PURPOSE

To succinctly update information on the pathogenesis, etiology, diagnosis, and treatment of neovascular glaucoma based on a systematic review of available literature and to provide summary recommendations rated for their importance to clinical outcome.

CLINICAL RELEVANCE

Neovascular glaucoma is a devastating ocular disease that often results in loss of vision. The current standard of care includes retinal ablation and control of increased intraocular pressure with medical and surgical therapy. LITERATURE REVIEW METHODOLOGY: The authors conducted a MEDLINE literature search of articles published in English from 1966 to the present. Each article reviewed was rated as to the strength of evidence it provided, and summary ratings for the strength of evidence supporting clinical recommendations were generated.

RESULTS

Level A (most important to patient outcome) recommendations for the diagnosis of neovascular glaucoma include a high index of suspicion, a full ocular examination including undilated gonioscopy, and pupil examination. In regard to treatment, Level A recommendations include treatment of the underlying disease origin, complete panretinal photocoagulation (if retinal ischemia is a factor), and medical control of both elevated intraocular pressure and inflammation. Level B recommendations (moderately important to patient outcome) encompass glaucoma surgery to control intraocular pressure when medical therapy is unsuccessful, although the ideal surgical procedure is unknown. Currently, trabeculectomy with antimetabolite therapy, aqueous shunt implants, and diode laser cyclophotocoagulation are the preferred surgical treatment options.

CONCLUSIONS

The current literature on neovascular glaucoma has few articles that provide strong evidence in support of therapy recommendations (level I). Future research studies are needed to address areas in which the current evidence is moderately strong (level II) or weak, consisting only of a consensus of expert opinion (level III). Whenever practicable, these studies should be prospective, randomized clinical trials.

Evaluation of hemodynamic changes in the ophthalmic artery with color Doppler ultrasonography after strabismus surgery

PURPOSE

To investigate the blood flow changes in ophthalmic artery with color Doppler ultrasonography after strabismus surgery.

METHODS

Twenty eyes of 19 patients who underwent recession or resection surgery on two horizontal rectus muscles in 1 eye were examined using color Doppler ultrasonography preoperatively and 1 week and 1 month postoperatively. Measurements from both eyes of 16 age- and sex-matched normal subjects served as control data. The systolic maximum velocity, mean velocity, end-diastolic velocity, pulsatility index, and resistance index of the ophthalmic artery were determined. The Mann-Whitney U test was performed for comparison of the control and study group preoperatively for any hemodynamic parameter. Statistical comparison of the preoperative and postoperative measures in the study group was performed with Friedman's two-way analysis of variance.

RESULTS

No difference (P>.05) was observed preoperatively between the study and control groups for any hemodynamic parameter in the ophthalmic artery. Although the ophthalmic artery showed a slight increase in systolic maximum velocity 1 month postoperatively, there were no statistically significant differences (P>.05) in velocities or resistance in the ophthalmic artery at any interval.

CONCLUSION

Two horizontal rectus muscle operations in a previously unoperated eye do not cause significant hemodynamic changes in the ophthalmic artery. However, further studies are needed to obtain more information about the effect of multiple vertical rectus muscle operations on the blood flow parameters of the ophthalmic artery.

The scanning laser ophthalmoscope

The imaging of the fundus of the eye poses two major technical challenges. First, it is necessary for both the illuminating and reflected beams to pass through the same aperture, the iris. In some commonly used instruments this leads to the use of levels of illumination close to the maximum tolerable by a patient. Second, in order to visualize the different structures present in the various layers of the fundus it is necessary to perform tomographic imaging. The scanning laser ophthalmoscope provides an answer to these particular problems. By scanning the fundus with a narrow laser beam most of the area of the iris is then available for the reflected light and so the intensity of the illuminating beam can be kept low, making it more acceptable for patients. The use of confocal imaging allows 3D images to be produced. In this short review the performance of the instrument will be discussed and its application to a number of clinical problems in ophthalmology considered. Finally there will be a brief description of other instrumentation currently under development.

Disorders of perfusion of the anterior segment of the eye

BACKGROUND

We have investigated the vascular perfusion of a wide variety of conditions of the anterior segment using fluorescein angiography.

METHODS

The conditions were classified and findings reported according to the system set out below. Patients underwent full ocular examination. Fluorescein angiography of the anterior segment was carried out when indicated to investigate iris atrophy and neovascularisation. Specular microscopy of the corneal endothelium was used to detect changes in this tissue.

RESULTS

The hypoperfusion was variable in degree and accompanied by varying degrees of iris hypoplasia and atrophy with neovascularisation. The degree of neovascularisation depended upon its rapidity of development, the pre-existing state of vascular perfusion and the underlying pathological condition.

CONCLUSIONS

Hypoperfusion with resultant ischaemia and neovascularisation is common in conditions of the anterior segment. An understanding of the changes is valuable in treating many conditions affecting the anterior segment. The changes observed may also occur elsewhere in the physical system and may be a significant part of the ageing process, either as scattered, disparate processes or as part of a general disease process.