Decrease in Anti-VEGF Injections After Post-injection Endophthalmitis in Patients With Neovascular Age-Related Macular Degeneration

Introduction: To evaluate the effect of antivascular endothelial growth factor (anti-VEGF)-related endophthalmitis on intravitreal injection (IVI) frequency in patients with neovascular age-related macular degeneration (nAMD). Methods: A retrospective chart review was performed of all cases of post IVI endophthalmitis that occurred in Edmonton, Alberta, Canada, between 2012 and 2019. Contralateral eyes affected by nAMD but without endophthalmitis served as a control group. The main outcome measures were the frequency of anti-VEGF injections, visual acuity, and activity of choroidal neovascularization before and after endophthalmitis. Results: Seventeen eyes met the inclusion criteria, 2 (12%) of which never resumed IVI after endophthalmitis because of the quiescence of disease. Post-endophthalmitis eyes received IVI less frequently in the 1 year after endophthalmitis (mean 0.52 ± 0.42 IVI/month) than those that received IVI 1 year before endophthalmitis (1.09 ± 0.36 IVI/month) (P = .001). The 17 contralateral eyes also received anti-VEGF injections less frequently after endophthalmitis than before (P = .001). There was no significant change in optical coherence tomography markers of disease activity in cases or controls. Conclusions: In patients with nAMD, endophthalmitis resolution is associated with a decrease in anti-VEGF injection frequency. The same decrease in anti-VEGF injection frequency is also seen in contralateral eyes unaffected by endophthalmitis. Markers of disease activity remain unchanged in both eyes, suggesting disease quiescence despite reduced IVI frequency.

Immediately sequential bilateral cataract surgery (ISBCS) adapted protocol during COVID-19: quality-improvement initiative

OBJECTIVE

To describe the steps, hurdles, and recommendations for implementation of the immediately sequential bilateral cataract surgery (ISBCS) evidence-based protocol at a high-volume Canadian tertiary care centre.

DESIGN

Quality-improvement study.

PARTICIPANTS

A total of 406 patients who underwent ISBCS from July 2020 to December 2020. Patients were selected based on specific inclusion and exclusion criteria including psychosocial factors, refractive error and consent. This initiative impacted staff at all levels involved with cataract surgery.

METHODS

The Model of Improvement framework was used and involved numerous discussions with multidisciplinary teams of ophthalmologists, nursing and support staff, management, pharmacists, and medical device reprocessing teams. This initiative was created and refined via a thorough review of the literature and current best practices. It was implemented in July 2020 after a nursing "huddle." Any adverse outcomes and overall impact were collected from various levels of staff involved.

RESULTS

Each eye was treated as a separate surgery with a double time-out per bilateral case. Additional measures were taken to ensure different lot numbers for medications, equipment, and materials. This practice increased surgical volume by approximately 25% and reduced the number of patient visits by 50%, reducing potential COVID-19 exposure.

CONCLUSIONS

The resulting protocol from our study may be useful to other centres wishing to integrate ISBCS as one example of successful implementation. Of the 406 cases of ISBCS performed, we report zero cases of toxic anterior segment syndrome or endophthalmitis. In times of decreased elective surgeries, ISBCS is a safe and effective option to supplement surgical volume and provide significant patient benefits.

Detecting Glaucoma in Rural Kenya: Results From a Teleglaucoma Pilot Project in Nyamira, Kenya

PRECIS

A teleglaucoma (TG) case-finding model was used in Kenya. Of the patients, 3.46% had definite glaucoma and 4.12% were glaucoma suspects. Most cases were of moderate to advanced stage and referred for further assessment.

PURPOSE

The aim was to evaluate glaucoma prevalence in a high-risk population using a TG model.

METHODS

Patients aged 35 or over were referred to the TG program from the outpatient diabetic and hypertensive clinics at Nyamira District Hospital (NDH) and from community awareness programs. Comprehensive ophthalmic examination included structured history, visual acuity, intraocular pressure, central corneal thickness, stereoptic nerve, and macular images. A glaucoma specialist provided diagnosis and management recommendation through virtual consultation. Glaucoma diagnosis and staging were based on at least 1 eye meeting the optic nerve criteria as specified by the Canadian glaucoma guidelines.

RESULTS

In all, 1206 participants were seen and 19 of these could not complete the examination. Of 1187 patients, 56% were women and the mean age was 56.60±12.36 years. Of the patients, 11.8% had images that were ungradable in at least 1 eye. The prevalence of glaucoma and glaucoma suspects was 3.46% (n=42) and 4.12% (n=50), respectively. The proportion of patients with early, moderate, advanced, and absolute glaucoma was 2.4%, 33.3%, 52.4%, and 2.4%, respectively. Other diagnoses (pathology in at least 1 eye) included cataract in 13.2%, diabetic retinopathy in 1.48%, and optic atrophy in 1.98%. Of the patients, 28.2% were referred to the Innovation Eye Centre, Kisii, for further assessment.

CONCLUSION

A structured TG program detected glaucoma in 3.46% of a rural Kenyan population. Timely patient referral was also initiated.

Distinguishing Central Serous Chorioretinopathy From Neovascular Age-Related Macular Degeneration: A Prospective Study

Purpose:

This article identifies clinical features that differentiate central serous chorioretinopathy (CSR) from neovascular age-related macular degeneration (nAMD) and uses this information to develop a diagnostic tool.

Methods:

A prospective observational study was conducted of patients with a new diagnosis of CSR, nAMD, or indeterminate presentation. All patients underwent clinical assessment, axial length measurement, enhanced-depth imaging–optical coherence tomography, and intravenous fluorescein angiography. A final consensus diagnosis was derived following review of these factors.

Results:

A total of 56 eyes of 56 patients were enrolled (CSR = 34; nAMD = 22). The subfoveal choroidal thickness was greater in the CSR group (421 ± 106 µm) than the nAMD group (219 ± 91 µm, P < .001). The following odds ratio of CSR reached statistical significance: age 70 and younger (72.00, 95% CI: 11.99-432.50), subfoveal choroidal thickness greater than or equal to 300 µm (33.92, 95% CI: 4.06-283.18), dome-shaped neurosensory detachment (13.24, 95% CI: 3.22-54.45), retinal pigment epithelial changes (0.31, 95% CI: 0.10-0.97), subretinal hyperreflective material (0.11, 95% CI: 0.03-0.42), and fibrovascular pigment epithelial detachment (0.05, 95% CI: 0.01-0.47). A stepwise CSR vs nAMD clinical decision-making algorithm is proposed.

Conclusions:

Choroidal thickness is increased in CSR when compared with nAMD. The presented odds ratios and the CSR vs nAMD clinical decision-making tool can be applied to distinguish CSR from nAMD.

Rate of retinal tear and detachment after neodymium:YAG capsulotomy

PURPOSE

To determine the rate of retinal tear and retinal detachment (RD) after neodymium:YAG (Nd:YAG) laser capsulotomy for posterior capsule opacification (PCO) after cataract surgery.

SETTING

Province-wide outpatient and hospital settings, Alberta, Canada.

DESIGN

Database study.

METHODS

Eleven years of billing records data were collected to assess the rate of retinal tear and/or RD after Nd:YAG laser capsulotomy. A period of 90 days from Nd:YAG was considered the at-risk period, although statistics for 10 years of data were included in the study. Risk was calculated as a rate (%) of retinal tear or RD after Nd:YAG laser capsulotomy.

RESULTS

The study comprised 92 654 discrete billing records yielding 73 586 ocular procedures for the analysis of the rate of retinal tear and/or RD after Nd:YAG laser capsulotomy. There were 67 287 Nd:YAG capsulotomies for PCO performed during the study. The 90-day risk for retinal tear after Nd:YAG was 0.21%; 720 retinal tears occurred in the study population at some point after the procedure. The rate of RD was 0.60%, with 2219 RDs occurring at some point after Nd:YAG capsulotomy. The cumulative risk for retinal tear or detachment at 3, 6, 9, and 12 months was 0.21%, 0.30%, 0.36%, and 0.43% and 0.60%, 0.96%, 1.19%, and 1.39%, respectively. The rates of retinal tear and detachment varied significantly between age categories.

CONCLUSIONS

There was an increased risk for RD in the first 5 months after Nd:YAG, with a return to a baseline plateau thereafter. As such, the rate of retinal tear after Nd:YAG capsulotomy at 5 months was 0.29%, whereas the rate of RD was 0.87%.

Optimizing preoperative requirements for outpatient cataract surgery at the Royal Alexandra Hospital

OBJECTIVE

To evaluate preoperative testing for cataract surgery, implement stakeholder-driven change, and increase the number of patients who arrived for surgery with complete preoperative requirements, for the purpose of delivering safe, high-quality, and cost-effective care for patients.

DESIGN

Quality improvement.

PARTICIPANTS

Cataract surgery patients, health care staff in Ophthalmology Day Surgery, an Ophthalmology improvement team, the Clinical Section Heads of Ophthalmology and Anaesthesia, Quality Consultants, and members of the Quality Council participated in this study.

METHODS

A lean quality improvement approach was used to define and build understanding of the problem. Between July and November 2016, a chart-based reporting system captured all patients who arrived for cataract surgery with expired or incomplete preoperative requirements. A cost analysis was completed, and evidence was reviewed to ensure alignment with best practice preoperative recommendations.

RESULTS

On average, 25% (619/2451 over a 17-week period) of patients per day arrived at the Ophthalmology Day Surgery for cataract surgery with incomplete and/or expired physical history forms and ECGs. An improvement team worked to implement a radical improvement idea and relied on an existing questionnaire to ensure patient safety preoperatively.

CONCLUSIONS

Based on the literature, best practice guidelines, and a cost analysis, it was decided that patients undergoing routine cataract surgery in Edmonton Zone Hospitals under regional anaesthesia would no longer require physician history and physicals and ECGs. Elimination of the preoperative requirements for all but select high-risk patients meant that 100% of patients who arrived for cataract surgery would not have outstanding presurgery requirements.

Prospective randomized controlled trial of phaco-trabectome versus phaco-trabeculectomy in patients with open angle glaucoma

OBJECTIVE

To compare the efficacy and safety of ab interno trabeculectomy with the Trabectome combined with cataract surgery (phaco-AIT) versus Trabeculectomy with mitomycin C combined with cataract surgery (phaco-Trab) in open-angle glaucoma.

METHODS

A prospective randomized controlled trial with a single surgeon and surgical center was undertaken. Patients were recruited from July 2009 to October 2014. Primary outcomes were mean intraocular pressure (IOP) at 6 months and surgical complications. Secondary outcomes were mean IOP at 12 months, achievement of target IOP, number of glaucoma medications, and rate of secondary surgery.

RESULTS

The trial was ended early before achieving our intended sample size due to difficulties in recruitment and lack of clinical equipoise over time. Nineteen patients were enrolled, 10 phaco-AIT and 9 phaco-Trab. Baseline IOP was 20.0 ± 5.3 in phaco-AIT and 23.1 ± 6.4 mm Hg in phaco-Trab (p = 0.22). IOP decreased to 17.5 ± 3.8 and 16.0 ± 6.0 mm Hg at 6 months (p = 0.54), and 16.8 ± 2.7 and 17.1 ± 5.0 mm Hg at 1 year (p = 0.57), respectively. Mean number of glaucoma medications at baseline was 1.8 ± 1.3 in phaco-AIT and 1.4 ± 1.1 in phaco-Trab (p = 0.59). Mean number of glaucoma medications decreased to 0.78 ± 1.39 and 0.38 ± 0.74 at 6 months (p = 0.68), and 0.44 ± 0.88 and 0.75 ± 0.89 at 1 year (p = 0.41), respectively. Mild and moderate complications were seen in both treatment groups, but severe complications were seen only in phaco-Trab. One secondary glaucoma procedure was required in the phaco-AIT group.

CONCLUSIONS

Phaco-AIT achieved similar IOP lowering at 6 and 12 months compared with phaco-Trab with a similar number of glaucoma medications required at 1 year, and no serious complications were identified in the Phaco-AIT group.

Comparative analysis of the safety and efficacy of intracameral cefuroxime, moxifloxacin and vancomycin at the end of cataract surgery: a meta-analysis

BACKGROUND

Current practice methods are unclear as to the most safe and effective prophylactic pharmacotherapy and method of delivery to reduce postoperative endophthalmitis occurrence.

METHODS

A systematic review and meta-analysis using Meta-analysis of Observational Studies in Epidemiology guidelines was performed to compare the efficacy of intracameral cefuroxime, moxifloxacin and vancomycin in preventing postphacoemulsification cataract surgery endophthalmitis. A safety analysis of intracameral antibiotics was concurrently performed.

DATA SOURCES

BIOSIS Previews, CINAHL, ClinicalTrials.gov, Cochrane Library, Dissertations & Theses, EMBASE, PubMed, ScienceDirect and Scopus were searched from inception to January 2017. Data were pooled using a random effects model. All articles were individually reviewed and data were extracted by two independent reviewers. Funnel plot, risk of bias and quality of evidence analyses were performed.

RESULTS

Seventeen studies with over 900 000 eyes were included, which favoured the use of intracameral antibiotics at the end of cataract surgery (OR 0.20; 95% CI 0.13 to 0.32; P<0.00001). The average weighted postoperative endophthalmitis incidence rates with intracameral cefuroxime, moxifloxacin and vancomycin were 0.0332%, 0.0153% and 0.0106%, respectively. Secondary analyses showed no difference in efficacy between intracameral plus topical antibiotics versus intracameral alone (P>0.3). Most studies had low to moderate risk of bias. The safety analysis showed minimal toxicity for moxifloxacin. Dosing errors led to the majority of toxicities with cefuroxime. Although rare, vancomycin was associated with toxic retinal events.

CONCLUSION

Intracameral cefuroxime and moxifloxacin reduced endophthalmitis rates compared with controls with minimal or no toxicity events at standard doses. Additionally, intracameral antibiotics alone may be as effective as intracameral plus topical antibiotics.

Phaco-trabectome versus phaco-iStent in patients with open-angle glaucoma

OBJECTIVE

To investigate efficacy and safety of phaco-trabectome (PT) versus phaco-iStent (Pi) for intraocular pressure (IOP) control in open-angle glaucoma (OAG).

DESIGN

Retrospective comparative case series.

PARTICIPANTS

A total of 70 eyes of 55 patients with OAG underwent either PT surgery by a single surgeon or Pi (insertion of 2 stents) by another surgeon in Canada between January 2010 and December 2012.

METHODS

The medical records of consecutive adult patients who underwent either PT or Pi surgery were reviewed. All patients who satisfied both the inclusion and exclusion criteria were included in the outcomes analyses. IOP reduction, reduction in glaucoma medication, safety profile, and best-corrected visual acuity were evaluated.

RESULTS

Thirty-six eyes of 30 patients had PT and 34 eyes of 25 patients had Pi. Baseline IOP was higher in the PT group (20.92 ± 5.07 mm Hg) than in the Pi group (17.47 ± 4.87 mm Hg; p = 0.026). At 12 months there was no significant difference between groups in relative reduction of mean IOP (PT -5.09 ± 5.73, 24% relative reduction vs. Pi -3.84 ± 3.80, 22% relative reduction; p = 0.331) or glaucoma medication use (PT -0.49 ± 1.17 vs. Pi -0.26 ± 0.73; p = 0.168) from baseline. However, Pi had significantly fewer individual complications (PT 20 vs. Pi 5; p < 0.0001) throughout the postoperative period.

CONCLUSION

At 12 months of follow-up, both techniques significantly lowered IOP, but fewer complications were observed in the Pi group.

Improving diabetic retinopathy screening in Africa: patient satisfaction with teleophthalmology versus ophthalmologist-based screening

Purpose:

To assess patient preference for diabetic retinopathy (DR) screening with teleophthalmology or face-to-face ophthalmologist evaluation in Nairobi, Kenya.

Materials and Methods:

Fifty seven diabetic patients from a one-stop multidisciplinary diabetic clinic (consisting of a diabetologist, nurse educator, foot specialist, nutritionist, ophthalmologist, and neurologist) in Nairobi, Kenya were included if they had undergone both a teleophthalmology (stereoscopic digital retinal photographs graded by an ophthalmologist remotely) and a traditional clinical screening exam (face to face examination). A structured questionnaire with a 5-point Likert scale was developed in both English and Swahili. The questionnaire was administered over the telephone. Ten questions were used to compare patient experience and preferences between teleophthalmology and a traditional clinical examination for DR. A mean score >3.25 on the Likert scale was considered favourable.

Results:

Successfully telephone contact was possible for 26 (58% male, 42% females) of the 57 patients. The mean ages of the male and female patients were 52.4 and 46.5 years respectively. Patients were satisfied with their teleophthalmology examination (mean 4.15 ± 0.97). Patients preferred the teleophthalmology option for future screenings (mean 3.42 ± 1.52). This preference was driven primarily by convenience, reduced examination time, and being able to visualize their own retina.

Conclusion:

In this study, diabetic patients preferred a teleophthalmology based screening over a traditional ophthalmologist-based screening. The use of teleophthalmology in Africa warrants further study and has the potential to become the screening model of choice. Cost effectiveness in comparison to an ophthalmologist-based screening also requires evaluation.

Surgeons' perception of fluoroscopic radiation hazards to vision

Exposure to ionizing radiation, such as that used in fluoroscopy, can lead to cataracts. This is relevant in orthopedic surgery as fluoroscopic procedures are commonly performed. In this study, we determined perceived level of: (1) personal risk, (2) awareness of risk for cataract formation due to ionizing radiation exposure, (3) awareness of occupational dose limits for ophthalmologic radiation exposure, (4) current radioprotective practices amongst orthopedic surgeons. Canadian Orthopaedic Association members were asked to participate and 264 responses (23%) were received. Many respondents believed that they were at least at moderate risk for cataract formation due to occupational radiation exposure (n = 107; 41%). Fifty-nine respondents (22%) indicated that they lacked sufficient knowledge to estimate risk and almost half (n = 120; 45%) reported having minimal awareness that ionizing radiation may contribute to cataractogenesis; almost 75% (n = 197) reported having minimal awareness that dose limits exist. The association between perceived risk and awareness was significant (P<.001). There is an information deficit among orthopedic surgeons regarding awareness of either the potential cataractogenesis risk due to radiation exposure or the dose limits.

Retention of the Boston keratoprosthesis type 1: multicenter study results

OBJECTIVE

To report the retention rate of the Boston keratoprosthesis type 1 and to identify risk factors for keratoprosthesis loss.

DESIGN

Cohort study.

PARTICIPANTS

A total of 300 eyes of 300 patients who underwent implantation of the Boston keratoprosthesis type I device between January 2003 and July 2008 by 19 surgeons at 18 medical centers.

METHODS

Forms reporting preoperative, intraoperative, and postoperative parameters were prospectively collected and subsequently analyzed at a central data collection site.

MAIN OUTCOME MEASURES

Keratoprosthesis retention.

RESULTS

A total cumulative number of 422 life-years of device implantation are included in this analysis. The average duration of follow-up was 17.1 ± 14.8 months, with a range of 1 week to >6.1 years. Ninety-three percent of the 300 Boston keratoprosthesis implants were retained at their last follow-up, corresponding to a retention time of 396 patient-years or 1.42 years/keratoprosthesis. The probability of retention after 1 year and 2 years was 94% and 89%, respectively. During the study period, 21 (7%) eyes failed to retain the device; the reasons for keratoprosthesis loss include sterile keratolysis (9), fungal infections (8), dense retroprosthetic membranes (3), and bacterial endophthalmitis (1). Multivariate analysis demonstrated 3 independent risk factors for keratoprosthesis loss: autoimmune cause (hazard ratio [HR], 11.94; 95% confidence interval [CI], 3.31-43.11), ocular surface exposure requiring a concomitant tarsorrhaphy (HR, 3.43; 95% CI, 1.05-11.22), and number of prior failed penetrating keratoplasties (HR, 1.64; 95% CI, 1.18-2.28).

CONCLUSIONS

The Boston keratoprosthesis type 1 seems to be a viable option for eyes that are not candidates for penetrating keratoplasty (PK). Ocular surface disease due to an autoimmune cause demonstrated the lowest retention rate.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Ocular microbiology trends in Edmonton, Alberta: a 10-year review

OBJECTIVE

Methicillin-resistant Staphylococcus aureus (MRSA) has been recognized as an increasingly common cause of nosocomial infections since the 1980s.(1) Reports of ocular infections due to MRSA are composed primarily of case reports. But a recent report from the United States suggests that ocular infections due to MRSA are about to become more common than methicillin-sensitive S. aureus (MSSA).(2) However, this observation is not consistent with anecdotal experience at the University of Alberta. The purpose of this study is to evaluate the ocular microbiology trends in a tertiary care eye center in Canada.

METHODS

Cross-sectional study using a computer search of the DynaLIFE(DX) Diagnostic Laboratory Services database for all positive ocular microbiology cultures and in vitro antibiotic susceptibilities performed in the Edmonton area.

RESULTS

Over a 10-year period, between 2000 and 2010, 6.4% of S. aureus isolates were MRSA; there were 2030 MSSA and 129 MRSA isolates, including 46 MSSA and 4 MRSA isolates from deep eye cultures. The prevalence of MRSA over the total number of S. aureus isolates, regardless of specimen source, steadily increased in the 10-year period, from 0.5% in 2002 to 12.6% in 2010. Gram-positive cocci were the most common organisms to cause ocular infections (82.6%). In vitro susceptibility of ocular MSSA and MRSA samples demonstrated 100% sensitivity to vancomycin.

CONCLUSIONS

The prevalence of MRSA ocular infections, although still uncommon, appears to be increasing in Edmonton, Alberta.

The prevalence of diabetic retinopathy as identified by teleophthalmology in rural Alberta

OBJECTIVE

The purpose of this study was to assess the prevalence of diabetic retinopathy (DR) as identified by teleophthalmology in a sample population of people with diabetes living in rural Alberta and to identify the risks and benefits of a teleophthalmology program for these patients.

DESIGN

Retrospective consecutive case series.

PARTICIPANTS

Three hundred ninety-four diabetic patients (788 eyes).

METHODS

Medical histories were obtained, following which patients underwent visual acuity and intraocular pressure measurements and stereoscopic, 7-field, digital retinal photography. Images were graded by ophthalmologists in Edmonton, Alta., according to a modified Early Treatment Diabetic Retinopathy Study scoring template. Diagnosis, treatment, and follow-up recommendations were communicated to local health care providers and data were collected for review.

RESULTS

Three hundred ninety-four patients (788 eyes) were assessed via 593 teleophthalmology visits over the 3-year period. DR was identified in 27.2% of patients (2.3% with proliferative DR and 24.9% with nonproliferative DR). A variety of other diagnoses, independent of DR, were also made. Recommendations for follow-up teleophthalmology and in-person referral were completed in 76.8% and 87.3% of patients, respectively, although many were completed later than was recommended. Teleophthalmology saved approximately 450 round trips from Edson to the nearest urban centre (Edmonton) over the 2-year period, equating to approximately 1900 hours and 180 000 km of driving.

CONCLUSIONS

Teleophthalmology can effectively identify DR while reducing travel time and distance for patients with diabetes living in a rural community. However, many patients did not follow up or attend referral appointments in a timely fashion, underscoring the need for ongoing quality assessment.

Visual acuity after intravitreal triamcinolone for diabetic macular edema refractory to laser treatment: a meta-analysis

OBJECTIVE

To quantify the effect on visual acuity of intravitreal triamcinolone for the treatment of laser-refractory diabetic macular edema (DME).

STUDY DESIGN

Meta-analysis of eligible studies identified by searching MEDLINE, EMBASE, the Cochrane Library, and Google.

PARTICIPANTS

7 randomized controlled trials and 3 cohort studies.

METHODS

A search of the literature between 1950 and September 2008 identified 540 articles. Studies that evaluated the efficacy of triamcinolone for the treatment of DME refractory to laser photocoagulation, reported visual acuity data, and compared the intervention with an appropriate control group were included. Exclusion criteria were studies of non-DME, triamcinolone used as an adjunct to another treatment, and triamcinolone delivery other than intravitreally.

RESULTS

Using a random-effects model, there was a statistically significant summary mean difference in visual acuity of -0.313 logarithm of the minimum angle of resolution (logMAR) units (95% CI -0.551, -0.074) after 1 month of follow-up. This difference declined to -0.125 logMAR units (95% CI -0.181, -0.070) by 3 months and to -0.043 logMAR units (95% CI -0.090, 0.003) by 6 months. No evidence of publication bias was present. There was a high level of heterogeneity in this group of studies (meta-analysis of 1-month follow-up data: Q-statistic = 21.987, p< 0.001), attributable primarily to study design.

CONCLUSIONS

These meta-analyses demonstrate that intravitreal triamcinolone results in a temporary improvement of visual acuity in patients with laser-refractory DME, with a peak benefit of approximately 3 lines of visual acuity 1 month postinjection.

Web-Based Grading of Compressed Stereoscopic Digital Photography versus Standard Slide Film Photography for the Diagnosis of Diabetic Retinopathy

PURPOSE

To evaluate the ability of Joint Photographic Experts Group (JPEG) compressed, stereoscopic, digital photography to identify clinical levels of diabetic retinopathy, detect clinically significant macular edema (CSME), and make appropriate referral recommendations as compared with Early Treatment Diabetic Retinopathy Study (ETDRS) standard film photography.

DESIGN

Prospective, clinic-based, comparative photographic format validation study.

PARTICIPANTS

Two hundred four eyes from 102 consecutive, new, diabetic patients with a median duration of diabetes of 12.5 years were enrolled and analyzed.

METHODS

After pupillary dilation, a trained ophthalmic photographer obtained 2 sets of images: standard ETDRS, stereoscopic 7-field 35-mm film photographs and high-resolution, digital images of the same 7 standard fields (stereoscopic images of fields 1 and 2). Two masked readers graded both sets of images. The 35-mm film photographs were graded by hand using a written template. Digital photographs were compressed, uploaded to a web site, and graded by a web-based, computer-assisted ETDRS algorithm. The ETDRS level of diabetic retinopathy, presence of retinal thickening, and referral recommendation based on these 2 diagnoses were recorded and compared.

MAIN OUTCOME MEASURES

The presence of CSME, ETDRS level of diabetic retinopathy, and referral threshold diabetic retinopathy.

RESULTS

Film and compressed digital grading levels were compared using a simplified ETDRS categorization scheme. Film and digital gradings were highly correlated with exact agreements for level of diabetic retinopathy, CSME, and referral thresholds >87% and kappa levels >0.71. McNemar's testing found no statistically significant difference between compressed digital images and film when comparing referral thresholds (defined as the presence of CSME and/or ETDRS level > or = 61; P = 0.76).

CONCLUSIONS

A modified ETDRS protocol (stereoscopic images of fields 1 and 2 only) with 16:1 JPEG image compression and computer-assisted ETDRS grading algorithm has excellent reproducibility when compared to standard ETDRS stereoscopic slide-film photography. An internet-based teleophthalmology system can correctly and reliably (kappa = 0.78) identify patients requiring referral for CSME and proliferative diabetic retinopathy (PDR; ETDRS level > or = 61).

Benefits of stereopsis when identifying clinically significant macular edema via teleophthalmology

BACKGROUND

The need to incorporate stereopsis into a teleophthalmology system is controversial. Detection of hard exudate in the macula is suggested by some as an adequate surrogate for direct observation of retinal thickening. This study was designed to determine how accurate the detection of hard exudate is as a surrogate for stereoscopic detection of clinically significant macular edema (CSME).

METHODS

120 patients with diabetes underwent clinical retinal examination with contact-lens biomicroscopy by a retinal specialist. The presence or absence of CSME was recorded. On the same day as clinical grading, 30 degrees stereoscopic digital photographs of the macula were captured. At least 2 months after clinical examination, the digital images were viewed by masked graders for the presence or absence of hard exudate and retinal thickening.

RESULTS

207 eyes of 106 patients had complete data sets for both diagnostic modalities. The sensitivity of hard exudate (93.9%) in predicting the presence of CSME was similar to that of direct stereoscopic observation of retinal thickening (90.9%), with p = 0.5. On the other hand, digital stereopsis was significantly more specific (92.9%) than was hard exudate (81.6%) in predicting the presence of CSME (p < 0.001). This difference was maintained even when controlling for image quality.

INTERPRETATION

Although the presence of hard exudate within the macula is a sensitive surrogate marker for CSME, it is less specific than stereoscopic evaluation. Any American Telemedicine Association category 3 teleophthalmology system that utilizes hard exudate as a surrogate marker for CSME may refer patients unnecessarily for clinical evaluation.

A likelihood approach to estimating sensitivity and specificity for binocular data: application in ophthalmology

Binocular data typically arise in ophthalmology where pairs of eyes are evaluated, through some diagnostic procedure, for the presence of certain diseases or pathologies. Treating eyes as independent and adopting the usual approach in estimating the sensitivity and specificity of a diagnostic test ignores the correlation between eyes. This may consequently yield incorrect estimates, especially of the standard errors. The paper proposes a likelihood-based method of accounting for the correlations between eyes and estimating sensitivity and specificity using a model for binocular or paired binary outcomes. Estimation of model parameters via maximum likelihood is outlined and approximate tests are provided. The efficiency of the estimates is assessed in a simulation study. An extension of the methodology to the case of several diagnostic tests, or the same test measured on several occasions, which arises in multi-reader studies, is given. A further extension to the case of multiple diseases is outlined as well. Data from a study on diabetic retinopathy are analysed to illustrate the methodology.

JPEG compression of stereoscopic digital images for the diagnosis of diabetic retinopathy via teleophthalmology

BACKGROUND

Canada's vast size and remote rural communities represent a significant hurdle for successful monitoring and evaluation of diabetic retinopathy. Teleophthalmology may provide a solution to overcome this problem. We investigated the application of Joint Photographic Experts Group (PEG) compression to digital retinal images to determine whether JPEG compression could reduce file sizes while maintaining sufficient quality and detail to accurately diagnose diabetic retinopathy.

METHODS

All 20 patients with type 2 diabetes mellitus assessed at a 1-day teleophthalmology clinic in northern Alberta were enrolled in the study. Following pupil dilation, seven 30 degrees fields of each fundus were digitally photographed at a resolution of 2008 x 3040 pixels and saved in uncompressed tagged image file format (TIFF). The files were compressed approximately 55x and 113x their original size using JPEG compression. A reviewer in Edmonton randomly viewed all original TIFF images along with the compressed JPEG images in a masked fashion for image quality and for specific diabetic retinal pathology in accordance with Early Treatment Diabetic Retinopathy Study standards. The level of diabetic retinopathy and recommendations for clinical follow-up were also recorded. Exact agreement and weighted kappa statistics, a measure of reproducibility, were calculated.

RESULTS

Exact agreement between the compressed JPEG images and the TIFF images was high (75% to 100%) for all measured variables at both compression levels. Reproducibility was good to excellent at both compression levels for the identification of diabetic retinal abnormalities (K = 0.45-1), diagnosis of level of retinopathy (kappa = 0.73-1) and recommended follow-up (kappa = 0.64-1).

INTERPRETATION

The application of JPEG compression at ratios of 55:1 and 113:1 did not significantly interfere with the identification of specific diabetic retinal pathology, diagnosis of level of retinopathy or recommended follow-up. These results indicate that JPEG compression at ratios as high as 113:1 has the potential to reduce storage requirements without interfering with the accurate and reproducible teleophthalmologic diagnosis of diabetic retinopathy. This pilot project demonstrates the potential for JPEG compression within a digital teleophthalmology viewing system.

High-resolution stereoscopic digital fundus photography versus contact lens biomicroscopy for the detection of clinically significant macular edema

PURPOSE

The purpose of this study was to compare high-resolution stereoscopic digital photography to contact lens biomicroscopy (CLBM) for the diagnosis of clinically significant macular edema.

STUDY DESIGN

Comparative, prospective, observational case series.

PARTICIPANTS

One hundred twenty diabetic patients.

METHODS

Patients underwent clinical retinal examination with CLBM by a retinal specialist. On the same day as clinical grading, patients received high-resolution stereoscopic digital imaging of the macula. The stereoscopic digital images were viewed using liquid crystal shutter goggles at least 2 months after clinical examination by a single masked grader for the presence or absence of diabetic retinopathy.

MAIN OUTCOME MEASURES

Presence or absence of the Early Treatment of Diabetic Retinopathy Study criteria for clinically significant macular edema (CSME) overall, CSME 1, CSME 2, CSME 3, macular edema, microaneurysms, intraretinal hemorrhage, and hard exudate.

RESULTS

Two hundred seven eyes of 105 patients had complete data sets from both diagnostic modalities. Exact agreement was high for all identified pathologic conditions: CSME overall, 83.6%; CSME 1, 83.6%; CSME 2, 96.1%; CSME 3, 88.5%; macular edema, 75.0%; microaneurysms, 77.9%; intraretinal hemorrhage, 83.7%; and hard exudate, 73.1%. Sensitivity ranged from 50.0% (CSME 2) to 90.6% (CSME overall). Specificity ranged from 90.0% (macular edema) to 99.0% (CSME 2).

CONCLUSIONS

High-resolution stereoscopic digital photography is both sensitive and specific when identifying CSME and correlates well with the accepted standard of CLBM for the diagnosis of CSME.

Identification of diabetic retinopathy by stereoscopic digital imaging via teleophthalmology: a comparison to slide film

BACKGROUND

Diabetic retinopathy is a leading cause of vision loss in North America. We compared mydriatic seven-field stereoscopic digital imaging to 100 ASA slide film photography for the identification of diabetic retinopathy via teleophthalmology.

METHODS

Patients from a northern Alberta community with diabetes mellitus diagnosed by a physician were asked to participate in a teleophthalmology pilot project. Patients were enrolled at four different times between October 1999 and June 2000. Seven 30 degree fields of the retina were photographed with both slide film and digital imaging (resolution 2008 x 3040 pixels) through a dilated pupil. Slide film was developed and reviewed in a masked fashion by a retinal specialist. Digital images for each patient were transmitted by satellite to Edmonton and analysed a minimum of 2 months after the original slide film. Retinal abnormalities were graded with the use of the Early Treatment Diabetic Retinopathy Study extension of the modified Airlie House classification. We calculated the sensitivity and specificity of digital imaging for the identification of features of diabetic retinopathy as seen on slide film. Pearson's correlation coefficient was also calculated.

RESULTS

A total of 121 patients (241 eyes), of whom 114 (94.2%) had non-insulin-dependent diabetes, participated in the study. The average duration of diabetes was 8.5 years. Of the 121 patients 57 (47.1%) had diabetic retinopathy, 12 (9.9%) had clinically significant macular edema and 2 (1.6%) had neovascularization. Pearson's correlation coefficient for the presence of retinopathy between slide film and stereoscopic digital imaging was 0.92 for microaneurysms, 0.80 for hemorrhages, 0.45 for intraretinal microvascular abnormalities, 0.32 for venous beading, 1.00 for neovascularization of the disc, 1.00 for neovascularization elsewhere in the retina and 0.97 for clinically significant macular edema (p < 0.001). The correlation between the two techniques for severe nonproliferative diabetic retinopathy (NPDR) was 0.86 and for high-risk proliferative diabetic retinopathy 1.00 (p < 0.001).

INTERPRETATION

Stereoscopic digital imaging has a high level of correlation with slide film for the identification of most features of diabetic retinopathy, including microaneurysms, hemorrhage, severe NPDR, high-risk proliferative diabetic retinopathy and clinically significant macular edema.

Tele-ophthalmology via stereoscopic digital imaging: a pilot project

Diabetic eye disease is present in remote communities across Canada. A pilot study was designed to assess the feasibility of stereoscopic digital imaging to identify levels of diabetic retinopathy via teleophthalmology. Diabetic patients were assessed for diabetic retinopathy by seven field stereoscopic digital imaging through a dilated pupil. Images were transferred by satellite to a tertiary eye center for review by a retinal specialist. Images were viewed stereoscopically on a video monitor, with grading of all images using a modified Early Treatment Diabetic Retinopathy Study (ETDRS) classification. Patients found to have treatable diabetic retinopathy were transferred to a tertiary eye center for assessment and treatment by a retinal specialist. One hundred patients (199 eyes) had stereoscopic digital imaging of the retina. Microaneurysms were identified in 70 eyes, hard exudates in 31 eyes. Two eyes were identified with neovascularization of the disc (NVD) and 15 eyes with clinically significant macular edema (CSME). All eyes identified by stereoscopic digital imaging with treatable disease were confirmed by clinical examination with contact lens biomicroscopy. Stereoscopic digital imaging of the retina enables the identification of diabetic retinopathy. Further research is needed to delineate the sensitivity and specificity of stereoscopic digital imaging when compared to slide film and clinical examination.