Optic Nerve Head Shape as a Predictor of the Formation of Acquired Pits of the Optic Nerve (APONs)

Acquired pits of the optic nerve (APONs) are an area of focal loss of neural tissue associated with a discrete area of depression/excavation within the optic cup at the level of the lamina cribrosa. It is commonly associated with glaucoma and can be seen on the optic disc when examining the back of a patient's eye. It causes a characteristic visual field defect in the central 5-10 degrees of vision which has a significant impact of a patient's daily activities. There is no treatment to restore vision once it has formed.

Previous studies suggest mechanical stress across this part of the eye may have role in the formation of APONs. The investigators therefore hypothesise that if a patient has a more elliptical shaped optic disc, which would have more irregular mechanical stress across it, it may have a higher risk of an APON forming.

Patients with glaucoma attending the ophthalmology department at University Hospital of Wales have regular photographs taken of the optic nerve/optic disc as part of their routine clinical care in order to monitor the condition. The research team, who are all practicing ophthalmologists in the department, will review anonymised photographs to find optic discs with APONs, and another group with glaucoma but no APONs to use as a control. The research team will then measure the dimensions of the optic disc to determine if APONs are more common in optic discs with a more elliptical shape. The patients' clinical notes will then need to be accessed to collect data on the age, sex and diagnosis. This data will be anonymised using ID numbers once collected.

The final outcomes of the study will the average measured dimensions of the optic disc in each group, and the position that the APON occurs.

Study Overview

• Status: Completed
• Conditions: Glaucoma
• Intervention / Treatment: Other: No intervention. Purely observation

• Study Type: Observational
• Enrollment (Actual): 91

Contacts and Locations

Study Locations

• United Kingdom
  • Cardiff, United Kingdom, CF14 4XW
    • University Hospital of Wales

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 50 years to 110 years (Adult, Older Adult)
• Accepts Healthy Volunteers: N/A
• Genders Eligible for Study: All

• Sampling Method: Non-Probability Sample

Study Population

Patients under the care of University Hospital of Wales Ophthalmology Department with optic nerve head photographs taken as part of routine clinical care for monitoring of glaucoma.

Description

Inclusion Criteria:

• Documented diagnosis of primary open angle glaucoma (POAG) or normal tension glaucoma (NTG)
• Under the care of the ophthalmology department at University Hospital of Wales
• Available optic disc photograph
• Presence of an APON for disease group, no APON for control group

Exclusion Criteria:

• No documented diagnosis of POAG/NTG
• Other form of glaucoma - e.g. traumatic glaucoma/juvenile glaucoma
• Poor photograph quality
• Optic disc tilted so that the margin is obscured and cannot be demarcated
• Coexisting disc pathology, e.g. congenital optic disc pit

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Retrospective

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
APON; Retrospective review of routine clinical images from patients with an acquired pit of the optic nerve (APON), and a documented diagnosis of primary open angle glaucoma or normal tension glaucoma	Other: No intervention. Purely observation; Retrospective image analysis of the shape of the optic nerve head in both groups
No APON control; Retrospective review of routine clinical images from patients with NO acquired pit of the optic nerve (APON), and a documented diagnosis of primary open angle glaucoma or normal tension glaucoma	Other: No intervention. Purely observation; Retrospective image analysis of the shape of the optic nerve head in both groups

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Optic disc radius ratio	Comparison of the ratio of the maximum/minimum optic disc radius for optic discs with APONs and optic discs with glaucoma but no APON.	6 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The percentile rank of the disc radius at the position of the APON	The percentile rank of the disc radius at the position of the APON	6 months

Collaborators and Investigators

• Sponsor: Cardiff and Vale University Health Board

Study record dates

Study Major Dates

• Study Start (Actual): December 1, 2020
• Primary Completion (Actual): January 25, 2021
• Study Completion (Actual): January 25, 2021

Study Registration Dates

• First Submitted: October 26, 2020
• First Submitted That Met QC Criteria: October 29, 2020
• First Posted (Actual): October 30, 2020

Study Record Updates

• Last Update Posted (Actual): February 18, 2021
• Last Update Submitted That Met QC Criteria: February 17, 2021
• Last Verified: October 1, 2020

More Information

Terms related to this study

• Keywords: Glaucoma
• Additional Relevant MeSH Terms: Eye Diseases; Ocular Hypertension; Glaucoma
• Other Study ID Numbers: 7943

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No