Measuring Outcomes in Low Vision

Educational Objectives

The goal of this program is to improve assessment of low vision. After hearing and assimilating this program, the clinician will be better able to:

1. Assess visual acuity and patient-reported outcomes in patients with low vision.

Summary

Definitions: blind — no perception of light; legally blind — per the World Health Organization, visual acuity ≤20/200 or visual field ≤20° in the better eye; low vision (LV) — can use residual vision with, eg, magnification, text enhancement; ultra-low vision (ULV) — limited vision (for, eg, motion, light perception); functional vision — ability to use vision for daily function

Quantitative visual acuity assessment: Berkeley Rudimentary Vision Test (Bailey et al [2012]) — quantifies vision when individuals can only identify grating or black or white cards; Freiburg Visual Acuity and Contrast Test (Bach [1996]) — a freely available, computerized LV test

Perimetry: microperimetry — uses scanning laser ophthalmoscopy to assess retina location at time of stimulus presentation; ensures retesting of the same point; often inappropriate for patients with very LV; kinetic perimetry — appropriate for patients with very LV; requires a talented and experienced technician

Retinal images: optical coherence tomography allows measurement of retinal thickness and identification of biomarkers of disease progression; fundus autofluorescence detects areas of atrophy and the transition zone; adaptive optics (AO) allows imaging of the retina at single-cell resolution; functional AO uses different wavelengths to differently stimulate photoreceptors; patients with poor vision may find fixation difficult

Measuring functional vision: studies assessing mobility use standardized, real-life obstacles (eg, black and white) and biomotion trackers; however, using black-and-white contrast renders the situation unreal

Measuring patient-reported outcomes (PROs): include ULV Visual Functioning Questionnaire, Impact of Vision Impairment-Very LV, and the National Eye Institute Visual Function Questionnaire (inquires about, eg, nighttime vision, dark adaptation, peripheral vision loss)

Newer tools: full-field stimulus threshold testing (Roman et al [2022]) evaluates full-field perception of light; multiluminance mobility testing (Chung et al [2018]) assesses mobility in a laboratory-based setting

Challenges: IRDs have varying phenotypes; PRO measures may not be appropriate for patients who are elderly or have other health conditions; rare diseases have small cohorts; outcome measures require space (may be costly) and should meet regulatory requirements

Importance of advocacy: Foundation Fighting Blindness and support groups, including Retina International and Choroideremia Foundation, ensure relevance of outcome measures for commercialization of treatments

Patient perspectives on emerging therapies: Mack et al (2023) found that, while 92% of surveyed individuals with IRDs indicated acceptance for gene therapy, only 28% claimed to have good knowledge of therapy

Readings

Acton JH, Greenstein VC. Fundus-driven perimetry (microperimetry) compared to conventional static automated perimetry: similarities, differences, and clinical applications. Can J Ophthalmol. 2013;48(5):358-63. doi:10.1016/j.jcjo.2013.03.021; Britten-Jones AC, McGuinness MB, Chen FK, et al. A multinational survey of potential participant perspectives on ocular gene therapy. Gene Ther. 2024;31(5-6):314-323. doi:10.1038/s41434-024-00450-4; Chung DC, McCague S, Yu ZF, et al. Novel mobility test to assess functional vision in patients with inherited retinal dystrophies. Clin Exp Ophthalmol. 2018;46(3):247-259. doi:10.1111/ceo.13022; Mack HG, Britten-Jones AC, McGuinness MB, et al. Survey of perspectives of people with inherited retinal diseases on ocular gene therapy in Australia. Gene Ther. 2023;30(3-4):336-346. doi:10.1038/s41434-022-00364-z; Şahlı E, İdil A. A common approach to low vision: examination and rehabilitation of the patient with low vision. Turk J Ophthalmol. 2019;49(2):89-98. doi:10.4274/tjo.galenos.2018.65928.

Disclosures

For this program, members of the faculty and planning committee reported nothing relevant to disclose.

Acknowledgements

Dr. Ayton was recorded at The Johns Hopkins Retinal Degeneration and Visual Electrophysiology Conference, held September 15-16, 2023, in Baltimore, MD, and presented by Johns Hopkins University School of Medicine. For more information about upcoming CME activities from this presenter, please visit https://hopkinscme.cloud-cme.com. Audio Digest thanks the speakers and presenters for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0.50 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0.50 CE contact hours.

Lecture ID:

OP622303

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.