Correlation of Scheimpflug Densitometry Measurements of Corneal Haze With Disability Glare

April 5, 2022 updated by: University Hospitals Cleveland Medical Center
Disability glare is described as "halos" or "starbursts" around bright sources of light that can cause discomfort and reduce vision. The cornea is the clear "window" at the front of the eye, but certain conditions such as a previous infection can leave a scar. Corneal scars can cause disability glare by scattering and spreading incoming light instead of allowing it to focus on the back of the eye (retina) to get a crisp image. In this study, the corneal scar will be analyzed using a new device that measures scar density (Pentacam), and a relationship with disability glare will be made. This can help us further understand disability glare and make better decisions in the future on when to treat these scars to help patients see better.

Study Overview

Status

Withdrawn

Conditions

Detailed Description

Disability glare is a phenomenon commonly described as starbursts and halos that results in difficulty seeing clearly in the presence of bright "blinding" light. It can appear as if a veil of light is cast over the world outside. Optically, this occurs when incoming light is scattered in the eye instead of being focused on the retina. This is called straylight, and it diffusely illuminates the retina which causes desensitization of the photoreceptors and reduces the contrast of the retinal image (Lombardo & Lombardo, 2010). The main sources of scatter in the human eye are opacities in the clear ocular media, primarily due to diffusion and loss of transparency in the cornea and lens, as well as within the retina. While the lens is the largest contributor to light scatter (especially with cataract formation and aging), opacification of the cornea (e.g. scars or haze) can similarly cause intraocular light scattering, resulting in disability glare and decreased contrast sensitivity (Fan-Paul et al., 2002).

Due to the subjective nature of disability glare and contrast sensitivity, it is fairly difficult to develop a reliable objective way to measure and quantify this phenomenon. One of the most commonly used clinical tests for disability glare is the Brightness Acuity Tester (BAT), which is described as an ice cream scooper 60 mm in diameter with a 12 mm hole in the center. With the patient viewing a visual acuity chart through the hole, a uniform luminance at three different settings-high (white sand beach), medium (clear day), low (overhead lighting)-is used to induce glare and simulate the various real-life conditions. The drop in visual acuity with the various glare settings is used as a measure of disability glare. The BAT test has been found to be a reliable predictor of outdoor visual acuity (clinically validated for use in measuring disability glare secondary to cataracts), is ubiquitously available, and is easy to administer. To further and more accurately reflect real life situations, it can be used in conjunction with a contrast sensitivity chart rather than the regular black-on-white Snellen letter chart (Aslam et al., 2007). Contrast sensitivity can be tested using letter-based charts (e.g. Pelli-Robson letter sensitivity chart) that consist of letters of the same size but with decreasing contrast, or contrast gratings, which are based on sinusoidal waves of light (e.g. Vistech MCT-8000 or FACT).

Opacification of the cornea in the form of scars or haze is a natural response to a wide array of pathological insults (e.g. infection, degeneration, corneal dystrophies) and can result in light scatter and glare. Measurement of corneal haze was previously crudely performed via standard slit-lamp examination and human measurement. Recently, an automated, non-invasive, and objective method to measure corneal scar density was introduced using Scheimpflug imaging. This Pentacam device (Oculus Optikgerate GmbH, Wetzlar, Germany) consists of a rotating camera that captures images of the cornea at an angle, and analysis of these anterior segment images can be employed to quantify scattered light in various diameters and depths of the cornea. The generated maps of the amount of scatter in different regions of the cornea are called corneal densitometry maps, and they are displayed along with maps of corneal topography (elevation) and pachymetry (thickness). Normative values for Scheimpflug densitometry have recently been established (Dhubhghaill et al., 2013). Measurements have also been obtained after various surgical procedures to analyze their impact on corneal clarity. This includes analysis of corneas after refractive surgery such as LASIK (Cennamo et al., 2011; Fares et al., 2012) and PRK (Takacs et al., 2011), as well as various forms of corneal transplantation (Koh et al., 2012; Bhatt et al., 2012; Arnalich-Montiel et al., 2013; Ivarsen & Hjortdal, 2013) and collagen cross-linking (Gutierrez et al., 2012; Greenstein et al., 2010). Furthermore, it has been used to characterize pathological conditions including infectious keratitis (Otri et al., 2012; Orucoglu et al., 2014) and congenital corneal opacities (Elfein et al., 2013). However, no functional correlation has been made with these anatomical maps, and the relationship between scattered light as measured by densitometry and its effect on visual function such as contrast sensitivity and disability glare has not been well-characterized.

Study Type

Observational

Contacts and Locations

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

Study Locations

  • United States
    • Ohio
      • Cleveland, Ohio, United States, 44106
        • University Hospitals Case Medical Center

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

Ages Eligible for Study

18 years and older (ADULT, OLDER_ADULT)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

This will be a prospective study in which all eligible and willing patients will undergo the same workup. The expected duration is 1 year, and the trial will be stopped once the needed number of subjects has been enrolled. Testing will be performed on the day of the routine clinical visit and will only extend the appointment by less than 30 minutes.

All patients receiving ophthalmological care at University Hospitals (both at the main Case Medical Center site and the satellite offices at Westlake and Landerbrook) who meet the inclusion and exclusion criteria would be eligible for this study. Subjects will be identified who have an isolated corneal scar in one eye and otherwise healthy eyes with no clinical evidence of lens or retinal pathology. Patients will be enrolled between September 6, 2014 and September 5, 2015, with the goal of recruiting at least 80-100 subjects.

Description

Inclusion Criteria:

  • Age 18 years or greater
  • Presence of corneal scar in one eye
  • No clinical evidence of any other intraocular pathology

Exclusion Criteria:

  • Clinical evidence of other ocular pathology (e.g. cataracts)
  • Pediatric patients less than 18 years old
  • Bilateral corneal pathology
  • Presence of active corneal inflammation/infection
  • Presence of degenerative corneal disease
  • History of prior corneal surgery (e.g. corneal graft)

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

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Disability glare
Time Frame: 1 year
BAT measurements of disability glare
1 year
Visual quality
Time Frame: 1 year
NEI-VFQ25 questionnaire on functional visual quality
1 year
Contrast sensitivity
Time Frame: 1 year
Vistech contrast grating test
1 year
Visual acuity
Time Frame: 1 year
Visual acuity measured by Snellen chart
1 year

Collaborators and Investigators

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

Sponsor

University Hospitals Cleveland Medical Center

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

September 1, 2014

Primary Completion (ANTICIPATED)

September 1, 2014

Study Registration Dates

First Submitted

September 17, 2014

First Submitted That Met QC Criteria

September 17, 2014

First Posted (ESTIMATE)

September 19, 2014

Study Record Updates

Last Update Posted (ACTUAL)

April 13, 2022

Last Update Submitted That Met QC Criteria

April 5, 2022

Last Verified

April 1, 2022

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • IRB 04-14-30

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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