David R. Chow

Use of telemedicine in screening for diabetic retinopathy

BACKGROUND A diabetic retinopathy screening program was introduced in September 2000 at a university-affiliated hospital in Montreal to meet the demands of an overburdened health care system. In this article we describe our initial experience with this program. METHODS A Canon CR6-45NM nonmydriatic 45 degrees camera was installed in the outpatient endocrinology clinic of the hospital. All patients who visited the clinic between September 2000 and January 2001 agreed to participate in the program. For each patient, a short questionnaire (age, sex, type of diabetes mellitus, time since diagnosis, prior retinal laser therapy and presence of end-organ involvement) was filled in. Subsequently at least two photographs were obtained of each eye. The photographs were sent via the hospital intranet to a retinal specialist within the hospital. The specialist reviewed the images unchanged and sent a report (grading of the level of diabetic retinopathy, presence or absence of macular hard exudates, quality of the images obtained and follow-up recommendations) via the hospital intranet to the endocrinology service. If the images were judged to be of poor quality and could not be read by the retina specialist, the patient was asked to see his or her regular ophthalmologist. RESULTS Images of 830 eyes of 415 patients (211 men and 204 women with a mean age of 57.5 years) were obtained. Most (83.6%) had type 2 diabetes. The average duration of disease was 13.3 years. Macular hard exudates were observed in 50 eyes (6.0%). Nonproliferative diabetic retinopathy was noted in 117 eyes (14.1%) and proliferative diabetic retinopathy in 15 eyes (1.8%). Unexpected findings included epiretinal membranes (in three eyes), macular holes (in two), bilateral cotton-wool spots (in one patient) and central retinal vein occlusion (in one eye). Overall, 10% of the patients were referred to a retina specialist based on the screening photographs. The main difficulty encountered with the screening program was image inconsistency. Overall, 35% of the images graded were felt to be of poor quality, the most common reason being poor exposure (84.4%). The quality of the images improved significantly over the study period (p < 0.01). Images obtained from patients aged 65 years or more were consistently poorer than those obtained from patients less than 65 years of age (p < 0.001). INTERPRETATION Despite the imperfections of such a system, our experience was favourable, allowing us to screen large numbers of patients in a cost-effective, reliable manner.

Ultrasound biomicroscopy of sclerotomy sites: the effect of vitreous shaving around sclerotomy sites during pars plana vitrectomy.

Purpose To study the difference in the amount of vitreous incarceration between conventional pars plana vitrectomy (PPV) and PPV with vitreous shaving around sclerotomy sites. Methods A dynamic in vivo examination using ultrasound biomicroscopy (UBM) was performed on the sclerotomy sites of 22 eyes after PPV. Patients were divided into two groups. In the study group (n = 11), the vitreous was completely shaved from the internal initial sclerotomy by cotton-tip depressed vitrectomy under coaxial illumination. In the control group (n = 11), no vitreous shaving was performed. Results Vitreous incarceration into sclerotomy sites was significantly less in the study group compared with the control group (P <0.001). No difference was seen among the three sclerotomy sites regarding vitreous incarceration within individual eyes. No difference was seen between eyes operated by right- and left-handed surgeons. Conclusions Vitreous shaving of sclerotomy sites using depressed vitrectomy significantly reduces vitreous incarceration. This may reduce the rate of sclerotomy-related complications following PPV in selected cases.

A genetic approach to stratification of risk for age-related macular degeneration

The genetic determinants of age-related macular degeneration (AMD) are reviewed and a novel approach to risk determination based upon inherited genetic polymorphisms and smoking history is presented. Although AMD was long thought to have primarily an environmental etiology, genetic variation is now known to account for the majority of the disease risk, with variations in the genes of the complement pathways playing a prominent role. Independent and validated clinical studies have implicated the C3 gene and its regulator, complement factor H (1q31.1), complement component 2 (6q21.33), and complement factor B (6q21.33). Subtle variations in complement activity increase the risk of symptomatic macular inflammation with age. A second group of AMD-associated genetic markers may aggravate complement-mediated inflammation by permitting retinal oxidative damage. Variation within the chromosomal site (10q26) coding a mitochondrial-associated protein (age-related maculopathy susceptibility 2) and an independent variation within the mitochondrial genome itself (A4917G) suggest a contributing pathophysiological role of retinal oxidative stress. A genetic panel of disease-susceptibility markers and smoking history can identify a group of individuals with greater than 65% lifetime risk of AMD. The introduction of genetic marker testing into clinical practice may identify patients with early disease who may be aided by presymptomatic monitoring or inclusion into trials of newer prophylactic agents.

Management of optic disk pit-associated macular detachment with tisseel fibrin sealant.

BACKGROUND Optic disk pit-associated macular detachment is a challenging condition to treat. Many surgical methods have been used to treat this condition with varying degrees of success. METHODS We managed optic disk pit-associated macular detachment in three cases with pars plana vitrectomy, fluid-air exchange, drainage of subretinal fluid through the optic disk pit, application of Tisseel fibrin sealant (Baxter Healthcare Corporation, CA) to the optic disk pit, C3F8 gas injection, and postoperative prone positioning. RESULTS All three patients maintained flat maculae and had improved vision. Patient 3 had postoperative macular hole formation. This was managed successfully with pars plana vitrectomy, internal limiting membrane peeling, fluid-air exchange, and C3F8 gas injection. CONCLUSION Our case series suggest that Tisseel fibrin sealant in conjunction with pars plana vitrectomy can be used successfully for management of optic pit disk-associated macular detachments.

Subconjunctival Lidocaine before Laser Treatment : A Randomized Trial

PURPOSE The aim of the study was to determine whether subconjunctival anesthesia is effective at reducing pain associated with laser retinopexy. DESIGN This was a single-center, prospective, patient-masked, randomized, controlled trial. PARTICIPANTS In the primary study group, 65 patients were recruited. Thirty-two patients (32 eyes) received anesthetic injection, and 33 patients (33 eyes) received the sham injection. The crossover study group consisted of 28 patients (56 eyes). METHODS Between February 2008 and April 2008, all patients who were consecutively booked to undergo panretinal photocoagulation (PRP) or peripheral laser retinopexy (PLR) were invited to participate in the study. Patients were randomized to receive subconjunctival lidocaine injection or a sham injection before their intended laser retinal treatment. These patients were defined as our primary study group. Patients who required a second laser treatment received the opposite injection in a masked fashion before laser retinal treatment. These patients were defined as our crossover group. Patients in both the primary study group and the crossover group were masked to the treatment given. After the laser treatment, patients completed a pain questionnaire. MAIN OUTCOME MEASURES The primary outcome was incidence of pain. The secondary outcome was severity of pain. RESULTS Primary study group: In the anesthetic treatment group, 19 patients (59%) experienced pain compared with 32 patients (97%) in the sham treatment group (P<0.001). Among the patients who did experience pain, the average pain score was 3.6 in the anesthetic treatment group and 4.1 in the sham treatment group (P=0.55). Crossover study group: In the anesthetic treatment group, 12 patients (43%) experienced pain compared with 28 patients (100%) in the sham treatment group (P<0.001). In patients who did experience pain, the average pain score was 3.3 in the anesthetic treatment group and 4.6 in the sham treatment group. Twenty patients (71%) preferred anesthetic to sham treatments, 1 patient (4%) preferred sham over anesthetic, and 7 patients (25%) thought both laser treatments were the same. CONCLUSIONS Subconjunctival 2% lidocaine significantly reduces the incidence of pain in patients who receive PRP or PLR.

Optical coherence tomography-based positioning regimen for macular hole surgery.

Purpose: To evaluate an optical coherence tomography (OCT)–based positioning regimen for patients undergoing macular hole surgery. Method: We reviewed the medical records of all patients in our practice who underwent macular hole repair, instituting a modified OCT-based positioning regimen from November 1, 2011 through July 31, 2013. The regimen consisted of prone positioning at the conclusion of surgery with daily OCT imaging until the hole was confirmed closed at which point positioning was halted. Clinical data that were collected and recorded included visual acuities, stage of hole, size of hole, chronicity, preoperative and postoperative OCT imaging, and length of follow-up. Results: We identified 33 patients (35 eyes) with a mean baseline visual acuity of 20/220, a mean hole size of 465 &mgr;m. The mean final (postoperative) visual acuity was 20/135 with a mean follow-up of 7.7 months. Six patients (17%) in our study were diagnosed with myopic degeneration. Thirteen patients (37%) were found to have chronic (≥12 months) holes, and 19 (54%) were found to have large holes (>400 &mgr;m). Overall, 28 eyes (80%) had persistent closure of macular holes with an OCT-based positioning regimen. In the absence of high risk factors, such as myopic degeneration, chronic or large holes, the closure rate was 92%. In the presence of 2 or 3 of these risk factors, the closure rate was 85% and 74%, respectively. Conclusion: The presence of 2 or 3 high risk factors, such as myopic degeneration, chronic holes (≥12 months), or large holes (>400 &mgr;m) can compromise outcomes resulting in reopening after apparent early closure. Based on the presence of these risk factors, a modified postoperative positioning regimen can be used to obtain complete and persistent closure.

Use of Evicel Fibrin Sealant in Optic Disc Pit-Associated Macular Detachment

Optic disc pit is a rare congenital anomaly of the optic nerve. Retinal detachment is a common complication with poor outcomes. Many surgical alternatives have been described for the treatment of this condition, producing variable results. Herein, the authors describe four cases of optic disc pit-associated macular detachment managed with pars plana vitrectomy, fluid-air exchange, drainage of subretinal fluid through the optic disc pit, temporal peripapillary laser, and application of Evicel fibrin sealant (human) (Ethicon, Bridgewater, NJ) over the optic disc head. Case 1 showed stable visual acuity and improvement of subretinal fluid. Cases 2 and 3 showed visual acuity and subretinal fluid improvements. At the 1-week follow-up visit, Case 4 showed almost total subretinal fluid absorption. The sealant invariably disappeared between 1 and 2 weeks and was tolerated by all patients. This case series suggests that Evicel fibrin sealant may be considered as an adjunctive option in the surgical treatment of optic disc pit-associated maculopathy. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:358-363.].

Optical coherence tomography angiography in chorioretinal disorders

Optical coherence tomography angiography (OCTA) is a novel imaging modality that incorporates blood motion contrast to create angiograms of the retinal vasculature in a noninvasive manner, without the use of dye. It is a safe procedure and can be repeated as frequently as desired. The use of OCTA for delineation of choroidal neovascular membranes, for the study of microvascular abnormalities in diabetic patients, to assess nonperfused areas in retinal occlusions and vascular changes in macular telangiectasia are some of the potential OCTA applications. However, it is not free of drawbacks. Major limitations include the small field of view and its great sensitivity to movement. As a result, it is prone to motion artifacts, leading to poor-quality images. The scope of the body literature regarding this new modality rapidly increases as we learn how to better use this technology. Our objective is to point overall aspects of OCTA, including its limitations and review some of its initial reports on chorioretinal diseases.

Optical Coherence Tomography Angiography of Chorioretinal Diseases.

Fluorescein angiography (FA) and indocyanine green angiography (ICGA) have been the gold standard for the evaluation of retinal and choroidal vasculature in the last three decades and have revolutionized the diagnosis of retinal and choroidal vascular diseases. The advantage of these imaging modalities lies in their ability to document retinal and choroidal vasculature through the dynamic assessment of contrast transit over time in the intravascular and extravascular spaces. However, disadvantages include the absence of depth resolution, blurring of details by contrast leakage, and the inability to selectively evaluate different levels of the retinal and choroidal microvasculature. In addition, these angiographic methods require intravenous dye, which may cause adverse reactions such as nausea, vomiting, and rarely, anaphylaxis. Optical coherence tomography angiography (OCTA) is a noninvasive imaging technique that, in contrast to dye-based angiography, is faster and depth-resolved, allowing in some cases for more precise evaluation of the vascular plexuses of the retina and choroid. The method has been demonstrated in the assessment of various vascular diseases such as venous occlusions, diabetic retinopathy, macular neovascularization, and others. Limitations of this imaging modality include a small registered field of view and the inability to visualize leakage and dye transit over time. It is also subject to a variety of artifacts, including those generated by blinking and eye movement during image acquisition. However, more than an alternative for FA and ICGA, OCTA is bringing new insights to our understanding of retinal and choroidal vascular structure and is changing fundamental paradigms in the clinical management of pathologic conditions. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:848-861.].

Resolution of bilateral multifocal subretinal cysticercosis without significant inflammatory sequelae

Cysticercosis is caused by Cysticercus cellulosae, the most common platyhelminth infesting the human eye. 1 C. cellulosae is the larval stage of the tapeworm Taenia solium. The adult worm lives in the intestine, whereas the larva can exist in various tissues, including the eye. Humans are usually infected following the ingestion of undercooked meat containing viable larvae. Although humans are usually the final hosts, ocular involvement is more typical when humans act as the intermediate hosts. The eye is the most common site of organ involvement following infection by Cysticercosis (13% to 46% of cases).1·2 Within the eye the subretinal space is most often involved;3 the organism has also been noted in the anterior chamber,4 vitreous,4•5 subconjunctival space,4 eyelids,6 orbit? and, rarely, optic nerve canal.8 Clinically most patients present with a unilateral unifocal subretinal lobulated cystic lesion. In most cases surgical intervention is performed to remove the organism from the subretinal space to prevent the severe inflammatory sequelae often associated with the death of the organism. We present a case of bilateral multifocal subretinal cysticercosis that resolved without significant inflammatory sequelae after a short course of systemic prednisone therapy.