Glare Test Research Articles

Visual Function Before and After Photorefractive Keratectomy for Myopia

To date, Snellen visual acuity and postoperative refraction have been used to evaluate the results of photorefractive keratectomy. However, other parameters, such as contrast sensitivity function and glare, may be affected by refractive surgery and lead to unsatisfactory visual performance. This prospective study is aimed at evaluating the effect of photorefractive keratectomy on contrast sensitivity function and glare. Static contrast sensitivity function, dynamic contrast sensitivity function, and glare sensitivity were evaluated in 22 myopic eyes before as well as 1, 3, and 6 months after photorefractive keratectomy. The eyes tested were divided into three groups, according to the amount of myopia: group I, from -4.00 to -8.00 diopters (D); group II, from -8.25 to -11.00 D; group III, from -11.25 to -20.00 D. Both static and dynamic contrast sensitivity function at the intermediate spatial frequencies were altered at 1 month after photorefractive keratectomy, with a trend toward recovery at 3 and 6 months postoperatively. Glare sensitivity was not significantly affected by surgery. Contrast sensitivity function and glare testing may show abnormalities in the presence of optimal visual and refractive results. These tests may result especially important for the evaluation of new refractive surgical procedures.

Long-term Results for Glare and Contrast Sensitivity in Patients with Diffractive, Multifocal Intraocular Lenses

OBJECTIVE: To test the long-term findings for glare and contrast sensitivity in patients with diffractive multifocal intraocular lenses. STUDY DESIGN: Measurements were done using the Mesoptometer II under standardized contrast level and brightness illumination settings (0.032 and 0.1 cd/m 2 brightness illumination for testing contrast sensitivity; 0.1 cd/m 2 brightness illumination and glare of 0.35 lux for glare testing). Furthermore the patients were tested on their ability to fulfil the requirements of the German Ophthalmological Society (DOG) for mesopic vision to obtain a driver's licence. PATIENTS: 40 patients with multifocal intraocular lenses (MIOL), aged 59.3 ± 9.1 years, were examined 2 years after lens implantation (3M815LE and 3M825LE) and compared to results of a control-group of 40 patients with monofocal IOLs. RESULTS: There were no significant differences testing contrast sensitivity. Patients with monofocals, however, reached significantly better results than patients with multifocals ( P < 0.01) when tested for visual acuity under low contrast conditions and glare sensitivity. 70% of MIOL-patients and 56% of monofocalpatients failed to meet the minimum requirements for driver's licence. CONCLUSIONS: Both patient groups showed decreased values for glare and contrast sensitivity when tested 2 years after cataract surgery.

Relative Sensitivity of Clinical Tests to Hydrophilic Lens- Induced Corneal Thickness Changes

The relative sensitivity of the van den Berg Straylightmeter, slitlamp biomicroscopy, a modified optical pachometer, Bailey-Lovie logMAR visual acuity (VA), and two glare tests (The Brightness Acuity Tester used with 10% contrast VA and Pelli-Robson contrast sensitivity) to hydrophilic contact lens-induced edema was assessed in 19 subjects (mean age 25.9 +/- 4.5 years). After baseline assessments, subjects wore thick hydrogel lenses on one eye which was patched tightly for 3 h. Assessments were repeated at frequent intervals after lens removal to assess recovery. None of the pachometer measurements returned to baseline within the 2-h monitoring period, although the majority were within 2% of baseline corneal thickness. The average time for the Straylightmeter scores to recover to baseline values after the lens removal was 90 min, which was similar to the time when visible edema at the slitlamp disappeared. The average time for return to baseline of logMAR VA and the two glare tests was consistently two to three times shorter than the time for the Straylightmeter score. The Straylightmeter therefore provided assessments of corneal edema similar to slitlamp examination and was more sensitive than VA or glare testing.

Experimental study of small intraocular lenses using an eye model

Contrast and glare tests were performed on small intraocular lenses (IOLs) using a new eye model, which was based on and about the same size as the Gullstrand eye model. Lenses with a small optic diameter were inserted and retinal images were observed under the operating microscope. Contrast and glare disability tests were done using the MCT-8000 contrast tester and the Miller-Nadler glare tester. No effect on contrast sensitivity attributable to glare was observed, but under severe glare light conditions a faint reflection around the circumference of the optic was found. Questionnaires from patients implanted with small optic IOLs confirmed that this phenomenon was similar to their symptoms.

Evaluating Visual Function in Cataract

This paper reviews recent research on the evaluation of visual function in cataract. Visual impairment in cataract is principally caused by increased intraocular forward light scatter. It is assumed that visual acuity (VA) measurements assess the impact of narrow angle light scatter. This also makes the measurement of high spatial frequency contrast sensitivity (CS) unnecessary. However, VA measurements alone are an inadequate assessment of visual impairment in some patients with cataract. In addition, it is suggested that a measurement of wide-angle light scatter is required. This can be evaluated directly using the van den Berg Straylightmeter, or indirectly using low spatial frequency CS or disability glare (DG) tests. The following are discussed: (1) the relative usefulness of these tests; (2) how they can be incorporated into the decision as to when to extract a cataract; and (3) the importance of considering binocular visual function.

Glare and Contrast Sensitivity With Cataracts-Reply

In Reply. —We wish to clarify and correct several misunderstandings of our article. Our conclusion that and decreased visual acuity account for little of this was based on our findings detailed in the subsections entitled Glare Tests, Contrast Sensitivity Tests, and PSC and Nuclear Opacity Subgroups. In these subsections we described the persistence of the effect of cataract, even after accounting for the effects of age and visual acuity on visual function. We shared Dr Marmor's concern that the glare disability and contrast sensitivity loss affecting cataract patients might be highly correlated with visual acuity loss. That is why we adjusted (but not corrected) our contrast sensitivity and glare data for acuity differences by using multiple regression techniques, as indicated in the Data Analysis section. In other words, even after accounting for the effect of reduced visual acuity, glare and contrast deficits remained. Dr Marmor's statement that a

Contrast sensitivity and glare in cataract using the Pelli-Robson chart.

There is a need for a convenient, clinically applicable test of glare disability which can be used in the preoperative evaluation of patients with cataract. In this study, contrast sensitivity (using the Pelli-Robson letter chart), near vision, and visual acuity were compared, with and without the introduction of a glare source in 70 patients with cataract, 15 with intraocular lenses, and 19 controls. A disposable pen torch was shone at the pupillary margin to induce glare. Contrast sensitivity demonstrated the most marked reduction during glare testing. Cortical cataracts were most affected followed by posterior subcapsular opacities. The glare disability was significantly less in pseudophakic patients and was absent from patients with non-cataractous phakic eyes. Glare testing with a disposable pen torch and a Pelli-Robson contrast sensitivity letter chart provides a rapid test of glare disability which can be easily incorporated into the clinical appraisal of patients with cataract.

Relationship between postoperative pupil size and disability glare

A group of 40 postoperative cataract patients had Miller-Nadler glare testing performed before and after midpupillary pharmacologic dilation. The results indicated that pupillary enlargement is associated with increased glare disability. For that reason it is essential to maintain normal pupil shape and function after cataract surgery, a difficult task in cases with miotic pupils.

The effect of early cataracts on glare and contrast sensitivity. A pilot study.

To establish the effect of cataracts on glare and contrast sensitivity, we graded type and amount of lens opacity in 110 subjects who underwent two glare tests (Brightness Acuity Tester and Berkeley glare test) and two contrast sensitivity tests (a sine-wave test and Pelli-Robson chart). Twenty-seven subjects (25%) had clear lenses (mean visual acuity of 20/20) and 83 subjects (75%) had early lens opacities (mean visual acuity of 20/40) in otherwise normal eyes. Multiple regression techniques were used to control for the effects of age and visual acuity. Glare test scores were significantly lower for nearly all patients with lens opacities than for patients with clear lenses and were the lowest for patients with lenses with posterior subcapsular opacity. Contrast sensitivity scores were lower for all patients with lens opacities than for patients with clear lenses at high frequencies only; all lens opacity groups scores similarly with each other. These results indicate reduced visual function among patients with cataracts whose visual acuity is only minimally impaired.

Comparison of Two Glare Measurement Methods through Light Scattering Modeling

Two methods used for evaluation of glare in patients with opacities of the ocular media are compared. One is a low contrast letter test and the other is a direct light scattering meter. Theoretical expressions for the measures obtained from the two different glare tests are derived in terms of the point spread function. Measurements on healthy test persons wearing diffusive glasses with known light scattering properties were in good agreement with the theory. Data from 26 cataractous eyes are presented and discussed in light of the theory.

Glare testing in pseudophakes with posterior capsule opacification.

We measured Snellen visual acuity under standard and glare conditions using the Allergan Humphrey 570 autorefractor in 46 pseudophakes (46 eyes) undergoing Neodymium-YAG laser posterior capsulotomy before and after treatment. All the patients studied had a best corrected vision of at least 6/12 but complained of visual disability and had clinically observable posterior capsule opacification. The patients did not have other known causes of glare disability. Following posterior capsulotomy, 30 (65%) patients showed an improvement in standard Snellen visual acuity and 44 (97%) an improvement in Snellen visual acuity under glare conditions. This difference was statistically significant (p < 0.001). Of the 16 patients whose standard Snellen visual acuity did not improve after posterior capsulotomy, 14 showed a reduction in glare disability. Glare testing was clinically useful in evaluating pseudophakes with posterior capsule opacification who complained of visual disability in spite of good Snellen visual acuity under standard testing conditions.

A New Test for the Evaluation of Disability Glare

We describe a new glare test that uses low contrast letters and a variable surround glare source. The test is easy to administer clinically and all test targets, luminance levels, glare geometry, and viewing conditions are well controlled. We found the most useful index of disability glare to be the difference in visual acuity scores for the low contrast chart in the no-glare and high-glare conditions and refer to this as the disability glare index (DGI). We tested a group of normal subjects who were divided into younger (age 15 to 41 years) and older (age 50 to 82 years) groups. The mean DGI value for the older group (10.2 +/- 4.8) was significantly higher than that for the younger group (2.3 +/- 1.9). The DGI is a better discriminator between the two groups than either high or low contrast visual acuity. We attribute the significantly higher DGI values in the older group to increased intraocular light scatter. We find DGI is poorly correlated with high contrast visual acuity (r = 0.33). Our findings suggest that this test of disability glare is sensitive to relatively modest changes in the ocular media. It is a potentially useful tool in detection and assessment of subtle media disturbances and in monitoring changes in the ocular media over a period of time.

Evaluation of a Clinical Glare Test Based on Estimation of Intraocular Light Scatter

A glare test based on psychophysical estimation of intraocular light scatter and using a flickering, annular glare source was evaluated. The parameters determining the accuracy of the test were studied. In particular the influence of background light and flicker frequency were investigated and optimum values for best accuracy were found. Based on these findings a versatile and simple apparatus was constructed. Forty patients with various degrees of cataract were investigated in a clinical study. Patients, who subjectively experience severe glare problems, indeed show high glare values as measured with the apparatus. No obvious relation between visual acuity and glare score was found. In comparison with glare tests using a stationary glare source the use of a flickering glare source is advantageous in terms of sensitivity and accuracy.

Excimer Laser Photorefractive Keratectomy for Myopia: Six-Month Results

Six eyes of six patients with myopia between -4.00 and -8.00 diopters underwent 193 nm Argon/fluoride excimer laser photorefractive keratectomy as part of a Phase II-A FDA Study. Six months after surgery, four of the six eyes had a spherical equivalent refraction within +/- 1.00 D; five eyes saw 22/30 or better without correction. All corneas demonstrated a faint reticulated subepithelial haze most visible by sclerotic scatter illumination. There were no episodes of delayed epithelial healing or recurrent erosions, and patients had no loss of contrast sensitivity, visual acuity under glare testing, or corneal sensation at the 3-month or 6-month visit. In this limited clinical trial, the excimer laser was capable of changing the refractive power of the cornea for correction of myopia. Long-term follow up of these patients will be necessary to determine the safety and efficacy of the procedure.

Survey of the clinical use of glare and contrast sensitivity testing

In August 1988, we surveyed a random 10% sample of the members of the American Society of Cataract and Refractive Surgery about their use of contrast sensitivity and glare testing. Of 396 surveys mailed, 214 were returned for a response rate of 54.3%. Thirty-six percent of respondents used glare testing alone; 5.6% used contrast sensitivity testing alone; 23.4% used both test modalities; 35% used neither. The most common uses of glare and contrast sensitivity testing were to evaluate visual function in patients who have cataracts, secondary cataracts, and/or intraocular lens problems.

Glare and Contrast Sensitivity for Clinicians

Visual acuity and visual fields are the most commonly used measures of vision, but clinicians and visual scientists have become increasingly aware of their limitations. The authors of this monograph have brought together information about two other parameters by which vision can be assessed: the contrast sensitivity function and the related effects of glare. Basic scientists, optometrists, and ophthalmologists approach these subjects from different perspectives in their reviews. "... useful to anyone with an interest in visual function testing." The book is well illustrated, with generous use of color plates. A glossary is appended to allow translation of what is necessarily a complex terminology. The editors are obviously enthusiastic about their topics, but take pains to point out that contrast sensitivity or glare testing should not be used as an excuse to perform marginal surgery, and even allow critical evaluation of their own glare-testing device. Several of the contributors point out

Glare-Test und Gegenlichtvisus bei Kataraktpatienten

Cataract patients and healthy subjects have been examined with the Miller-Nadler Glare-Tester to prove if the results of the glare test show any correlation between the glare disability score and the outdoor visual acuity facing sun. The outdoor vision of cataract patients with a high glare disability score was clearly impaired compared with their indoor vision. Healthy eyes with a normal glare disability score did not show any impairment of visual acuity facing sun. The results of the glare disability examination can therefore be used as a reference for the decision of a cataract operation.

Contrast Sensitivity and Glare Testing in the Evaluation of Anterior Segment Disease

Contrast Sensitivity and Glare Testing in the Evaluation of Anterior Segment Disease

A new glare test based on low contrast letters — Evaluation in cataract patients

A new simple glare test was designed and evaluated regarding clinical usefulness and reproducibility. The ability to recognize letters of equal size and varying contrast was determined with the absence and presence of glare sources above and below the letters. Ten patients with cataract, visual acuity of at least 0.3 and glare problems, and three age matched controls were tested, as well as one patient with glare complaints and exophoria, one with lens subluxation and one with cataract and no glare problem. The test was found to be cheap and simple to produce and useful for clinical testing. Normal eyes had no detectable reduction of letter contrast sensibility with glare. All cataractous eyes had a letter contrast sensitivity without glare that was well below that of the controls and under glare conditions they all had a drop in visual function that was unrelated to their visual acuity. The reproducibility was of a magnitude similar to that of other low contrast letter tests. Our conclusion is that this test will be a valuable tool in the evaluation of cataract patients providing information not only about glare-induced visual loss but also about contrast sensitivity, separating eyes with increased intraocular light scattering from normal eyes.

A sensitive disability glare test for assessing cataract

A sensitive disability glare test for assessing cataract