ISNT Rule in Normal Population

October 8, 2022 updated by: Amr Mohamed Sayed, Assiut University

Is the ISNT Rule Still a Rule : a Study to Determine Prevalence of the ISNT Rule and Its Variants in the Normal Population

This study sought to determine the percentage of normal eyes that followed the ISNT rule by retinal nerve fiber layer (RNFL) and neuroretinal rim thickness measurements using optical coherence tomography (OCT) , and secondarily, whether alternative rules may be more applicable or easily generalized.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Glaucoma is a disease of the optic nerve, which results in structural optic nerve head (ONH) damage and functional visual field (VF) loss. It has increased as a cause of global blindness from 4.4% in 1990 to 6.3% in 2010. Its global prevalence is also increasing from 3.54% or 64.3 million people in 2013 to a projected 111.8 million people by 2040. Detection of structural ONH damage is critical for early diagnosis, because ONH changes usually precede VF loss. Two cornerstone elements of the ONH and peripapillary examination are stereo disc photography and optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness measurements. By analyzing the neuroretinal rim in disc photos of normal subjects, Jonas et al found that the rim width typically exhibited a specific pattern of the inferior (I) rim being the widest, followed by the superior (S) rim, then the nasal (N) rim, and then the temporal (T) rim being the thinnest. This specific neuroretinal rim pattern was later coined by Elliot Werner as the "ISNT rule." Because neuroretinal rim loss is a hallmark feature of glaucoma, patients who deviate from the ISNT rule may need to be watched more closely for glaucoma. The RNFL, on the other hand, has also been shown in histological studies in normal, non-glaucomatous eyes to exhibit a similar pattern of the inferior quadrant being the thickest, followed by the superior, nasal, then temporal quadrant. Since RNFL thinning, particularly in the superior and inferior quadrants, is also a characteristic structural change in glaucoma, deviation from the ISNT rule for RNFL thickness may also be an early indicator of glaucomatous structural change. Therefore, many investigators have sought to determine whether the ISNT rule, either applied to the neuroretinal rim disc photos or to RNFL thickness measurements, is useful in the diagnosis of glaucoma or not. However, the optic disc photo ISNT rule studies are conflicting, with some finding the ISNT rule and its variants clinically useful, while others have not. In contrast, RNFL ISNT rule studies based on OCT findings are in uniform agreement, stating that the ISNT rule and its variants were not helpful in the diagnosis of glaucoma. Some have hypothesized that the ISNT rule is not easily generalizable to the individual, because the initial studies were derived from mean values. Therefore, some of the limitations of the ISNT rule may stem from the fact that it is unclear what percentage of individual normal eyes follow the ISNT rule. Other limitations may arise from the fact that perhaps other rules may be more common in the normal population.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Anticipated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
116

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

14 years to 76 years (Adult, Older Adult)

Accepts Healthy Volunteers

N/A

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

Normal population

Description

Inclusion Criteria:

  • a normal eye examination without ocular diseases except for cataracts
  • best corrected vision of > 6/12
  • a normal VF test result defined by a pattern standard deviation value of > 5% compared to age matched controls in the perimeter's normative database and a glaucoma hemifield test within normal limits
  • a spherical equivalent of between -5 and +5 diopters.

Exclusion Criteria:

  • unreliable VF testing with > 33% fixation losses, > 20% false positives, or > 20% false negatives.
  • any history of ocular hypertension or intraocular pressures > 21mmHg at the time of the visit;
  • inter-eye cup-to-disc ratio (CDR) asymmetry of > 0.2;CDR of > 0.4
  • history of a neurologic disease or systemic medication that could produce VF defects.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Cohort
  • Time Perspectives: Cross-Sectional

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
ISNT rule prevalence in normal population
Time Frame: Baseline
the percentage of normal eyes that followed the ISNT rule by retinal nerve fiber layer and neuroretinal rim thickness measurements using (OCT)
Baseline

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
variants of ISNT rule
Time Frame: Baseline
whether alternative rules may be more applicable or easily generalized than the ISNT rule like IS,IST, TSINT rule .
Baseline

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Assiut University

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Abd-Elnasser A Mohamed, PhD, Assiut university

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Anticipated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 1, 2022

Primary Completion (Anticipated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
December 30, 2023

Study Completion (Anticipated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 30, 2023

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
October 9, 2021

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 8, 2022

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
October 12, 2022

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
October 12, 2022

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
October 8, 2022

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
October 1, 2022

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • ISNT rule

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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