Evidence-based Canadian guidelines for tele-retina screening for diabetic retinopathy: recommendations from the Canadian Retina Research Network (CR2N) Tele-Retina Steering Committee

OBJECTIVE

The purpose of this report is to develop a consensus for Canadian national guidelines specific to a tele-medicine approach to screening for diabetic retinopathy (DR) using evidence-based and clinical data.

METHODS

Canadian Tele-Screening Grading Scales for DR and diabetic macular edema (DME) were created primarily based on severity grading scales outlined by the International Clinical Diabetic Retinopathy Disease Severity Scale (ICDR) and the Scottish DR Grading Scheme 2007. Other grading scales used in international screening programs and the clinical expertise of the Canadian Retina Research Network members and retina specialists nationwide were also used in the creation of the guidelines.

RESULTS

National Tele-Screening Guidelines for DR and DME with and without optical coherence tomography (OCT) images are proposed. These outline a diagnosis and management algorithm for patients presenting with different stages of DR and/or DME. General guidelines detailing the requirements for imaged retina fields, image quality, quality control, and follow-up care and the role of visual acuity, pupil dilation, OCT, ultra-wide-field imaging, and artificial intelligence are discussed.

CONCLUSIONS

Tele-retina screening can help to address the need for timely and effective screening for DR, whose prevalence continues to rise. A standardized and evidence-based national approach to DR tele-screening has been proposed, based on DR/DME grading using two 45° image fields or a single widefield or ultra-wide-field image, preferable use of OCT imaging, and a focus on local quality control measures.

Stage specificity of novel growth factor expression during development of proliferative vitreoretinopathy

OBJECTIVE

To compare the relative levels of connective tissue growth factor (CTGF), platelet-derived growth factor alpha (PDGF-AA), and hepatocyte growth factor (HGF) in glial and retinal pigment epithelial (RPE) cells of epiretinal membranes from proliferative vitreoretinopathy (PVR).

METHODS

A total of 37 PVR membranes, of various stages, underwent fluorescent immunohistochemisty and confocal laser scanning microscopy to localize CTGF, HGF, and PDGF-AA in RPE and glial cells.

RESULTS

Numerous RPE, and relatively fewer glial cells, were found in all stages of PVR. CTGF immunoreactivity increased from early to late stage PVR and was principally expressed by RPE cells in early stage, and by glial cells in late stage PVR. HGF, expressed by both RPE and glial cells, was principally expressed in mid-stage PVR. PDGF-AA, expressed by both cell types, demonstrated a uniform level of staining throughout all stages of PVR.

CONCLUSIONS

RPE and glial cells contribute to the expression of CTGF, HGF, and PDGF-AA during PVR, but with specific developmental patterns. PDGF-AA is expressed uniformly throughout all stages of PVR, while HGF expression peaks during mid stage, and CTGF expression is highest during late stage PVR. These results allow for the development of stage-specific therapeutics for PVR that may allow targeting of the early proliferative and/or the late tractional stages of PVR.

Pegaptanib for neovascular age-related macular degeneration

(1) Neovascular (wet) age-related macular degeneration (AMD) results from the growth of abnormal blood vessels under the retina (choroidal neovascularization). Sudden and permanent vision loss occurs as these vessels grow, leak, bleed, and scar. (2) A human protein, vascular endothelial growth factor (VEGF), is implicated in the development of wet AMD. Pegaptanib attaches to VEGF and blocks its action. (3) In two concurrent, high quality studies using identical research methods, pegaptanib demonstrated a therapeutic advantage over placebo for the prevention of vision loss due to neovascular AMD. (4) Pegaptanib is injected into the eye every six weeks. This carries the risk of endophthalmitis (intraocular infection), lens damage (if accidentally penetrated), and retinal detachment. Systemic side-effects have not been associated with pegaptanib.

Vitreous leptin levels in retinal disease

BACKGROUND/AIMS

The purpose of this study was to investigate the relationship between vitreous leptin levels and retinal diseases.

METHODS

Levels of vitreous leptin were evaluated in proliferative diabetic retinopathy (PDR) and a variety of other retinopathies including: macular disease, neovascular maculopathies, primary retinal detachments, and vascular occlusive disease.

RESULTS

In patients with PDR (N=7), the average vitreous level of leptin (37.4 ng/ml) was significantly higher than that in patients with PVR (<1.0 ng/ml, P<0.05). Vitreous leptin level in patients with PVR or macular disease (N=18), with or without diabetes, was not significantly different from the control subjects who had retinal detachment only (N=7).

CONCLUSION

The results show that the leptin level in vitreous taps is elevated in PDR. We suggest that leptin plays an active role in PDR.

Polypoidal choroidal vasculopathy masquerading as central serous chorioretinopathy

OBJECTIVE

To differentiate polypoidal choroidal vasculopathy (PCV) from central serous chorioretinopathy (CSC).

DESIGN

A retrospective, observational case series.

PARTICIPANTS

Thirteen patients originally diagnosed with CSC proved to have PCV after more extensive evaluation and follow-up.

METHODS

A clinical and angiographic review of patients with manifestations of CSC, including macular detachment.

MAIN OUTCOME MEASURES

Demographic data, funduscopic examination, and fluorescein and indocyanine green (ICG) angiographic findings.

RESULTS

Thirteen patients initially suspected of having CSC were ultimately diagnosed as having PCV. These eyes had exudative macular detachments secondary to a small caliber, polypoidal choroidal vascular abnormality or so-called polypoidal choroidal neovascularization. The clinical manifestations in the fundus varied. They included multiple, variably sized serous pigment epithelial detachments, neurosensory retinal detachment, lipid deposition, patchy atrophy of the pigment epithelium and indistinct staining from decompensation of the posterior blood-retinal barrier on fluorescein angiography. In reality, the suspected PEDs proved to be polypoidal lesions of PCV when imaged with ICG angiography.

CONCLUSIONS

The clinical diagnosis of CSC or PCV generally poses little challenge to the experienced retinal specialist. However, in CSC with persistent and/or recurrent exudation, a myriad of retinal pigment epithelial changes may evolve that make it difficult to differentiate these two entities. In such patients, ICG angiography is useful in differentiating CSC from PCV. An accurate clinical diagnosis is important since each of these entities, CSC and PCV, may differ in terms of their risk factors, natural course, and visual prognosis.

Polypoidal choroidal vasculopathy and neovascularized age-related macular degeneration

OBJECTIVE

To determine the nature and frequency of polypoidal choroidal vasculopathy (PCV) in a series of patients suspected of having neovascularized age-related macular degeneration (AMD).

METHODS

A prospective analysis of 167 consecutive, newly diagnosed patients aged 55 years or older with presumed neovascularized AMD was performed. All patients were examined with fundus biomicroscopy as well as fluorescein and indocyanine green angiography.

RESULTS

Choroidal neovascularization secondary to AMD was diagnosed in 154 (92.2%) of 167 patients; 13 (7.8%) patients had PCV. The patients affected by PCV were younger than those with AMD (P = .01). Peripapillary choroidal neovascularization was seen in 3 (1.9%) of 154 patients with AMD and 3 (23.1%) of 13 patients with PCV (P = .006). Significant drusen were present in 63 (70%) of 90 fellow eyes with unilateral AMD compared with only 1 (16.7%) of 6 eyes with PCV (P = .02). Only 5 patients with AMD (3.2%) were nonwhite compared with 3 patients with PCV (23.1%) (P = .02).

CONCLUSIONS

A measurable number of elderly patients with findings suggestive of neovascularized AMD and serosanguineous macular manifestations will instead have PCV. Polypoidal choroidal vasculopathy can occur in any sex or race, but is more commonly seen in the peripapillary area, without associated drusen, and in nonwhite patients. It is important to differentiate AMD from PCV because there are significant differences in the demographic risk profile, natural course, visual prognosis, and management of these patients.

A microendoscopic test card for ophthalmic endoscopes

Ophthalmic endoscopes allow examination of intraocular structures when traditional surgical microscopic visualization is limited or impossible. Periodic evaluation of the optical precision of these instruments is essential to ensure optimal intraoperative performance. A test card has been developed to aid in the calibration of ophthalmic endoscopes. Its 5 test targets assess white balance and fiberoptic bundle integrity, focus and resolution, orientation, color fidelity, and angle of view.

Releasable "U" suture for trabeculectomy surgery

Overfiltration after glaucoma surgery can lead to significant complications. Tight suturing of the trabeculectomy flap reduces this problem but can lead to higher pressure and poor drainage of aqueous. Releasable sutures often leave irritating exposed suture ends. We describe a simple two-arm releasable suture technique that leaves no exposed suture ends until one arm of the suture is removed. Good control of postoperative pressure with few complications was achieved in 28 cases using this technique, which allows manipulation at the slit lamp of the trabeculectomy flap, obviating laser lysis of the sutures.