Gaps in Glaucoma care: A systematic review of monoscopic disc photos to screen for glaucoma

Methodological quality of the review: Medium confidence

Authors: Paula Anne Newman-Casey, Angela J. Verkade, Gale Oren, and Alan L. Robin.

Geographical coverage: USA, Australia

Sector: Glaucoma

Sub-sector: Glaucoma care

Equity focus:  No

Review type: Other review

Quantitative synthesis method:  Narrative review

Qualitative synthesis method: Not applicable

Background:

Glaucoma continues to be the third leading cause of blindness in the United States despite proven treatments that can minimize vision loss, indicating that our medical interventions are not impacting disease burden for many Americans in a meaningful way. Glaucoma is also the second leading cause of blindness worldwide and this progression poses a serious economic burden. In order to address this gap in glaucoma care, there is a need to develop and implement improved methods for glaucoma screening. is one important arena in which our system for delivering glaucoma care is limiting our impact on the societal burden of vision-threatening disease. A more efficient, sensitive and specific screening process is necessary to facilitate the early diagnosis and treatment of primary open angle glaucoma.

Objectives:

This review aims to gather and analyze the effectiveness of screening for glaucoma using non-stereoscopic disc photos.

Main findings:

Six studies were identified that met all of the inclusion and exclusion criteria.

1. Mydriatic photographs with standard fundus camera and telemedicine protocol versus standard clinical exam: There was 87% agreement between the ophthalmologist evaluating the participant in-person and the tele-ophthalmologist for making the diagnosis of glaucoma suspect. The tele-ophthalmology protocol was 64% sensitive and 95% specific for the diagnosis of glaucoma suspect.
2. Mydriatic photographs with direct ophthalmoscope with custom digital video camera versus clinical exam: Of the 21 gradable images, the sensitivity for correctly identifying glaucoma suspects was 50% and the specificity was 100% compared to clinical exam.
3. Non-mydriatic photographs with a portable fundus camera versus clinical exam: The sensitivity to detect glaucoma based on age, sex, family history status and vertical cup-to-disc ratio >0.5 as identified by non-mydriatic, non-stereoscopic fundus photos was 67.4%, and the specificity to correctly identify disease was 93.6% compared to full examination by a glaucoma specialist. The test characteristics were essentially unchanged (sensitivity 69.8%, specificity 94.2%) when glaucoma status was determined by dilated fundus examination by a glaucoma specialist along with age, sex and family history of glaucoma. The glaucoma specialist reading the fundus images correctly classified 87.9% of those with glaucoma using monoscopic photos compared to full examination. When the grader was also given results from Humphrey Frequency Doubling Technology (FDT) testing, the correctly classified images increased to 93.9%, the sensitivity to detect glaucoma increased to 83.7%, and the specificity increased to 96.8%.
4. Mydriatic photographs with a portable fundus camera versus standard stereoscopic disc photos: The three ophthalmologists who were grading the photographs had a mean sensitivity of 73.7% (range 67%–87%) and specificity to correctly identify disease of 74.7% (range 68%–79%).
5. Stereoscopic versus monoscopic disc photographs compared to clinical exam: Under monoscopic viewing, 57% (146/256) of images were classified correctly whereas under stereoscopic viewing, 73% (186/256) of images were classified correctly. Though the statistical significance of this difference between the two viewing modalities was not reported, the author notes that this difference is clinically relevant.
6. Stereoscopic versus monoscopic disc photographs compared to clinical exam: Of photos of discs with known glaucoma, 81%±8% of stereoscopic photos were correctly classified and 76%±10% of monoscopic photos were correctly classified (p=0.37). Of photos of discs known not to have glaucoma, 83%±4% of stereoscopic photos were correctly classified and 78%±8% of monoscopic photos were correctly classified (p=0.44). There was no statistically significant difference between monoscopic and stereoscopic viewing conditions and the ability of the glaucoma specialist to correctly classify glaucomatous status based on disc photos.

Methodology: 

Inclusion criteria: evaluation of single-field, monoscopic photographs for the screening and diagnosis of glaucoma in comparison to standard diagnosis via stereoscopic disc photographs or clinical exam.

Exclusion criteria: any study in which all patients were not screened with both an imaging protocol and a gold standard exam. The gold standard was defined as either a clinical exam by an ophthalmologist or stereoscopic disc photographs evaluated by an ophthalmologist. outline of search:

This study used a systematic approach to searching the published literature using Pubmed and Embase. Final searches were conducted on June 27, 2014. Two searches were run on each database, the first including terms and medical subject headlines (MeSH) mapping to “telemedicine” and “glaucoma,” and the second search including terms mapping to “non-stereoscopic” and “glaucoma.” Articles chosen were restricted to the English language and only included published articles; abstracts were excluded.

Two independent researchers (PANC and AJV) evaluated the titles and agreed upon reading 77 abstracts of these references to determine their eligibility based on pre-determined inclusion criteria. After the criteria were applied, the two researchers screened the abstracts and determined that 29 full-length papers should be screened further. The references of the 29 papers were screened to ensure that the original search criteria had not missed any relevant citations, and no new relevant citations were found. (including population, intervention, study design (for example, RCTs and Quasi-experimental studies), outcomes and contexts), (including main databases and time period of search, data collection and synthesis).

Applicability/external validity:

The review focuses on studies from USA and Australia where the health service available for glaucoma is very high. The results of this study might be different in other settings. Despite this, the authors acknowledged that further research is needed to validate the use of monoscopic non-mydriatic photos taken with portable fundus cameras in identifying individuals at high-risk for glaucoma, both in the controlled setting of an eye clinic and in the real-world setting of a population-based study.

Geographic focus:

The review was focused specifically on high-income countries USA and Australia.

Summary of quality assessment:

Medium confidence was attributed in the conclusions of the review as the authors included published studies only in the review. In addition, the authors did conduct a thorough search of the literature to ensure that all relevant studies were included in the review. These limitations may impact on the overall findings of the review.