From the Department of Ophthalmology, Rush University Medical Center, Chicago, Illinois.
Presented at the American Society of Retina Specialists Annual Meeting, October 2008, Maui, Hawaii.
The authors have no financial or proprietary interest in the materials presented herein.
Supported by a grant from Optomap, Optos PLC, Dunfermline, Scotland.
The authors thank Pamela Hulvey and Kisung Woo for their help with retinal photography.
Address correspondence to Mathew W. MacCumber MD, PhD, Department of Ophthalmology, Rush University Medical Center, 1725 West Harrison Street, Suite 915, Chicago, IL 60612.
Cytomegalovirus (CMV), a double-stranded DNA virus of the Herpesviridae family, can cause retinal inflammation and uveitis in neonates and immunocompromised individuals. CMV retinitis is the most common ocular opportunistic infection in patients with acquired immune deficiency syndrome (AIDS).1,2 In healthy individuals, infection typically runs a flu-like benign course; however, CMV can be a major cause of morbidity in immunocompromised patients.
The diagnosis of CMV retinitis is primarily a clinical diagnosis, and fundus examination is the most common method for diagnosis.2 When assessing disease progression or response to therapy, important clinical characteristics are the size of the lesion and the appearance of its borders. Both of these characteristics can be evaluated and recorded with fundus photography. Previous photographs are necessary for accurate comparison and determination of changes in size or appearance. Currently, the standard of care for CMV retinitis includes periodic retinal examination with documentation with fundus photography to assess whether there has been progression in active lesions or whether new activity is seen in quiescent lesions.
The current conventional fundus photography system consists of a specialized low-power microscope with an attached camera. The normal field of view obtained with the current system ranges from 30° to 60°. A montage of photographs is taken to encompass up to 140° of the retina, and the photographs are combined to create a composite photograph. Often, lesions that are peripheral to this field of view cannot be photographed or are incompletely recorded.
The Optomap ultra-wide–field fundus photography system (Optos PLC, Dunfermline, Scotland) is a novel technology that allows imaging of up to 200° of the retina.3 It can provide documentation of peripheral pathology without montage, can detect peripheral angiographic pathology while obtaining macular views, and can potentially delineate autofluorescence and subretinal fluid. This digital system also allows for easy storage of the images and convenient comparison. The system is now being used by several centers for diagnosis and follow-up of posterior segment disease,4–9 but its usefulness in the management of inflammatory posterior segment disease has not been assessed. Moreover, no formal studies have compared the new ultra-wide–field system with the conventional montage photography system.
The current study compared the Optomap imaging system, a novel ultra-wide–field fundus imaging system, with conventional 45° nine-field fundus photography in the diagnosis and monitoring of patients with CMV retinitis.
Patients and Methods
This prospective, single-arm study was approved by the Rush University Medical Center institutional review board. Patients who were observed at the Rush University Medical Center for AIDS and CMV retinitis underwent conventional nine-field fundus photography with montage and Optomap ultra-wide–field imaging on the same day (Figs. 1 and 2). The conventional nine-field fundus photography followed a protocol as previously defined.10 Eye steering to maximize peripheral retinal views was not used for either imaging technique. Outcome measures included retinal area imaged, mean CMV retinitis lesion area imaged, and patient satisfaction, including perceived time required for photography, comfort, and preference of technique. Fundus montage photographs were created manually for the areas of retinitis and then scanned into a digital format (digital fundus photography was not permitted by protocol at the time of this study).
Figure 1. (A) Conventional Fundus Photography with Montage. (B) Optomap (Optos PLC, Dunfermline, Scotland) Ultra-Wide–Field Imaging of the Same Patient. The Ganciclovir Implant Is More Visible in This Image than in the Conventional Montage.
Figure 2. (A) Conventional Fundus Photography with Montage. (B) Optomap (Optos PLC, Dunfermline, Scotland) Ultra-Wide–Field Imaging of the Same Patient.
Image set analysis was performed with the ImageJ image processing program (National Institutes of Health software; available at rsbweb.nih.gov/ij). The total retinal area and CMV retinitis lesion area were compared between the two systems using the formula (Optomap area/montage area – 1) for each patient eye. Mean and standard deviation for these ratios were then calculated. Patients with CMV retinitis too peripheral to be visualized with either system, those with excessive scarring outside the area of CMV retinitis, and those with marked eyelid artifact on ultra-wide–field imaging were excluded.
Most study subjects completed a post-imaging patient satisfaction survey. Two additional subjects with AIDS and peripheral retinal pathology were included. The parameters for the survey included (1) perceived difference in imaging time required between conventional fundus photography and ultra-wide–field imaging and (2) perceived comfort and preference between conventional fundus photography and ultra-wide–field imaging.
A total of 19 eyes from 12 patients with CMV retinitis were imaged with both modalities. Three eyes were excluded because CMV retinitis was too peripheral to be visualized with either system. Three eyes were excluded because of excessive scarring as a result of retinal detachment repair or panretinal photocoagulation for proliferative diabetic retinopathy outside the area of CMV retinitis that obscured the borders of CMV retinitis. One eye was excluded because of marked eyelid artifact in the ultra-wide–field image (an early patient in the study for whom an earlier generation of the Optomap was used). Thus, 12 of the original 19 eyes imaged were included in the study.
Optomap ultra-wide–field imaging captured 48.3% greater total retinal area than standard fundus photography. Furthermore, ultra-wide–field imaging captured 40.0% more of the CMV retinitis lesion area than standard fundus photography (Table). Conventional photography did not capture the CMV lesions in two eyes. These differences were not statistically significant. The two imaging modalities were identical in detecting posterior lesions. Picture quality in the presence of media haze was comparable for conventional and Optomap images.
Table: Ratio of Optomap to Conventional Total and Lesion Areas
A total of 12 patients with AIDS completed the satisfaction survey. Ten patients had CMV retinitis in at least one eye. Two patients had another ocular disease (one with a history of syphilitic retinopathy and one with peripheral atrophy). Most patients (92%) perceived standard photography as taking too long, whereas 42% found Optomap ultra-wide–field imaging to take too long (Fig. 3A). Most patients (58%) found ultra-wide–field imaging more comfortable, whereas 42% found no difference in comfort. Overall, approximately 75% of patients preferred ultra-wide–field imaging to standard photography (Fig. 3B).
Figure 3. (A) Perceived Imaging Time Requirement for Conventional Fundus Photography and Ultra-Wide–Field Imaging. (B) Comfort and Preference for Conventional Fundus Photography and Ultra-Wide–Field Imaging.
CMV retinitis is a necrotizing viral infection that is relentlessly progressive in the setting of severe immune suppression, leading to blindness if not treated with appropriate antiviral drugs.1 A standard definition of retinitis progression is advancement of a lesion border by 750 μm or development of a new CMV lesion.2 Fundus examination with photography is an effective method used to document the activity or progression of CMV retinitis. Often, CMV retinitis lesions are found in the retinal periphery and they may not be photographed with standard fundus photography.
In comparing ultra-wide–field imaging versus standard fundus montage photography, we found that ultra-wide–field imaging captured a mean of 48.3% greater total retinal area and 40.0% greater CMV retinitis lesion area than standard fundus montage photography. Standard photography missed peripheral CMV lesions in two eyes. The wider imaging capability is seen in Figures 1 and 2. Although this difference was not statistically significant, these results suggest that ultra-wide imaging provides similar if not more accurate monitoring of peripheral CMV lesions. In addition, the increased peripheral imaging may also help to assess disease progression and response to therapy in other peripheral retinal conditions, such as diabetic retinopathy.9 Standard nine-field fundus and Optomap imaging followed protocols that did not include the maximum possible views of the periphery obtainable by some experienced photographers.
Although the number of patients surveyed was small, most patients perceived conventional photography to take too long, found ultra-wide–field imaging more comfortable, and preferred the ultra-wide–field imaging technique to standard photography. These patient satisfaction findings can be attributed to the multiple flash photographs required to obtain nine images, whereas ultra-wide–field imaging requires a single flash. The flashes may cause temporary discomfort and inconvenience as a result of photophobia.
Limitations of this study include the small sample size and imaging artifact. The performance of Optomap imaging for anterior lesions can decline as a result of decreased image quality and resolution with eccentricity.6 Eyelash artifact, particularly when imaging the inferior periphery, was seen in our study and has been reported previously.7 These artifacts were greatest early in our study and decreased with time, system improvements, and photography experience. In addition, the protocols used did not maximize conventional or Optomap imaging of the periphery through eye steering, and this may have added bias to the results.
Optomap ultra-wide–field imaging tended to capture a greater area of total retina and peripheral CMV retinitis lesions than conventional fundus montage photography. However, these results were not statistically significant. Patients tended to prefer ultra-wide–field imaging over standard photography because of the perceived decreased time requirement and increased comfort of use.
- Weinberg DV, Holbrook JT, Hubbard LD, et al. Clinician versus reading center assessment of cytomegalovirus retinitis lesion size. Ophthalmology. 2005;112:559–566. doi:10.1016/j.ophtha.2004.11.027 [CrossRef]
- Holbrook JT, Meinert CL, Van Natta ML, et al. Photographic measures of cytomegalovirus retinitis as surrogates for visual outcomes in treated patients. Arch Ophthalmol. 2001;119:554–563.
- Optos web page. Available at: www.optos.com.
- Manivannan A, Plskova J, Farrow A, et al. Ultra-wide-field fluorescein angiography of the ocular fundus. Am J Ophthalmol. 2005;140:525–527. doi:10.1016/j.ajo.2005.02.055 [CrossRef]
- Anderson L, Friberg TR, Singh J. Ultrawide-angle retinal imaging and retinal detachment. Semin Ophthalmol. 2007;22:43–47. doi:10.1080/08820530601162867 [CrossRef]
- Win PH, Young TA. Optos Panoramic200A fluorescein angiography for proliferative diabetic retinopathy with asteroid hyalosis. Semin Ophthalmol. 2007;22:67–69. doi:10.1080/08820530701331644 [CrossRef]
- Mackenzie PJ, Russell M, Ma PE, et al. Sensitivity and specificity of the Optos Optomap for detecting peripheral retinal lesions. Retina. 2007;27:1119–1124. doi:10.1097/IAE.0b013e3180592b5c [CrossRef]
- Dunphy RW, Wentzolf JN, Subramanian M, et al. Structural features anterior to the retina represented in panoramic scanning laser fundus images. Ophthalmic Surg Lasers Imaging. 2008;39:160–163. doi:10.3928/15428877-20080301-07 [CrossRef]
- Friberg TR, Gupta A, Yu J, et al. Ultrawide angle fluorescein angiographic imaging: a comparison to conventional digital acquisition systems. Opthalmic Surg Lasers Imaging. 2008;39:304–311. doi:10.3928/15428877-20080701-06 [CrossRef]
- Fundus Photograph Reading Center, University of Wisconsin–Madison. Protocol for grading cytomegalovirus (CMV) retinitis from fundus photographs: studies of the Ocular Complications of AIDS (SOCA) Research Group. Available at: eyephoto.ophth.wisc.edu/ResearchAreas/AIDS/NTIS_ALT/html.
Ratio of Optomap to Conventional Total and Lesion Areas
|Optomap/Conventional Total Area||Optomap/Conventional Lesion Area|
|1.651||Lesion not visible with conventional photography|
|1.574||Lesion not visible with conventional photography|