Threshold Amsler Grid Testing Research Articles

Scleral gas permeable contact lenses as a possible way of visual rehabilitation of patients with age-related macular degeneration

Low visual acuity, loss of the central visual field, metamorphopsia, distortion of lines and decreased contrast sensitivity cause reduced quality of vision in patients with age-related macular degeneration (AMD). Currently existing methods of visual rehabilitation for patients with AMD, such as telescopic intraocular and scleral lenses, are functionally and cosmetically unacceptable. The use of intraocular telescopic lenses is limited by the high risk of postoperative complications, low functional parameters, as well as by difficult ophthalmoscopy and lasting adaptation of patients. Telescopic scleral lenses have а low resolution, contain impermeable to oxygen parts and require wearing special switching glasses. However, scleral lenses have potential in developing an optimal method for vision correction in patients with AMD due to the presence of following advantages: wide optical zone, gas permeability, correction of refractive astigmatism in presbyopic patients and alleviation of dry eye symptoms. In conclusion, further clinical researches are required to develop a method for improving the quality of vision in patients with AMD by using scleral lenses with an objective test for evaluating the effectiveness of correction – the 3D computer-automated threshold Amsler grid test (3D-CTAG).

Quantifying Visual Dysfunction and the Response to Surgery in Macular Pucker

To measure the effects of macular pucker (MP) on macular structure and quantify function by measuring visual acuity (VA), contrast sensitivity (CS), and distortions. The effects of surgery were quantitatively evaluated using these measures. Prospective, comparative case series. Fifty-three patients with unilateral MP and normal fellow eyes: 24 operated MP subjects, 17 unoperated controls, and 12 reproducibility subjects. Posterior vitreous detachment was diagnosed by ultrasound and ellipsoid zone disruption (EZD) was determined by OCT, which also measured macular thickness and volume. Vision was assessed, bymeasuring VA (logMAR) and CS (Freiburg acuity contrast testing: Weber index, %W). A visual distortions index (%DI) was calculated using 3-dimensional threshold Amsler grid testing. Comparisons to controls were performed before surgery and at 1, 3, 6, and 12 months after vitrectomy/membrane peel without chromodissection. Posterior vitreous detachment (ultrasound), EZD (OCT), macular thickness and volume (OCT), VA (logMAR), CS (%W), distortions (%DI). Posterior vitreous detachment was present in 90% of MP eyes, but only 50% of fellow eyes (P< 0.001). All structural and functional indices were worse (28% to 5-fold) in the 24 operated MP eyes than the 17 unoperated MP eyes (P < 0.001). Before surgery, EZD was present in 33% of operated MP eyes but none of the unoperated MP eyes (P < 0.02). The macula was thicker (514±85 μm vs. 257±59 μm; P < 0.001) with greater volume (3.22±0.56 μl vs. 2.14±0.22 μl; P < 0.001) in operated MP eyes than normal fellow eyes. Before surgery, MP eyes had VA = 0.53 logMAR (Snellen equivalent, 20/67) vs. controls = 0.21 (20/32); P < 0.001; CS was 8.61±5.36 %W vs. controls = 3.71±1.47 %W (P < 0.001); and distortions were 7.61±12.6 %DI vs. controls = 0.13±0.61 %DI (P < 0.001). EZD was associated with worse VA (P < 0.01) and CS (P < 0.03) before and after surgery. Each outcome measure improved progressively at 1, 3, 6, and 12 months after surgery, but only %DI and macular volume normalized. These quantitative measures characterize the impact of MP on macular structure and function. All indices improved after surgery, but only distortions and macular volume normalized. Contrast sensitivity measurements and quantification of distortions can objectively assess visual dysfunction in MP and may be useful outcome measures of therapy.

Efficacy of conservative treatment in patients with dry form of age-related macular degeneration

To evaluate the efficacy of conservative treatment in dry AMD patients by means of 3D computer-automated threshold Amsler grid testing (3D-CTAG; Fink & Sadun, 2004). The study included 90 patients (180 eyes) with dry AMD divided into three groups. Group 1 (n = 30) was prescribed Vitrum Vision forte, 1 tablet b.i.d., group 2 (n = 30)--Vitrum Vision forte, 1 tablet b.i.d. and Vitrum Cardio Omega-3, 1 capsule b.i.d. Group 3 (n = 30), the controls, received Taurine 250 mg, 1 tablet b.i.d. Besides standard ophthalmic examination, all patients underwent 3D-CTAG before and after the treatment. The number of defects per eye (ND) and volume lost relative to the hill-of-vision (VLRH) were chosen as evaluation criteria. After 3 months of treatment ND decreased from 0.33 ± 0.02 to 0.22 ± 0.01 in group 1 (p < 0.01) and from 0.33 ± 0.02 to 0.2 ± 0.01 in group 2 (p < 0.01); VLRH decreased from 0.32 ± 0.02% to 0.15 ± 0.01% out of 693,000 [deg2%] in group 1 (p < 0.01) and from 0.32 ± 0.03% to 0.15 ± 0.01% out of 693,000 [deg2%] in group 2 (p < 0.01). In the controls both indices increased: ND from 0.32 ± 0.02 to 0.37 ± 0.02 and VLRH from 0.35 ± 0.24% to 0.49 ± 0.03% out of 693,000 [deg2%] (p < 0.01). The positive effect of Vitrum Vision forte in combination with Vitrum Cardio Omega-3 on macular function is comparable to that of monotherapy with Vitrum Vision forte. The maximum effect was achieved in patients with small scotomas (VLRH < 1.5% out of 693,000 [deg2%]).

Detecting recurrence of macular edema in patients with wet AMD after anti‐VEGF treatment using 3D‐CTAG test

AbstractPurpose To detect recurrence of macular edema inwet AMD patients after anti‐VEGF treatment using 3D‐Computer‐automated Threshold Amsler Grid testing (3D‐CTAG; Fink &amp;Sadun, 2004).Methods Wet AMD patients (n=10, 11 eyes) 6 months after 3 injections of Ranibizumab (Lucentis, Novartis). Group #1(n=5, 6 eyes): norecurrence. Group #2 (n=5, 5 eyes): recurrence confirmed by OCT. Indices: # of VF defects per eye (ND); lowest perceivable contrast level (CL); VF volume lost relative to hill‐of‐vision (VLRH); lost area grade (LAG): [scotoma area at lowest tested contrast sensitivity level/scotoma area at highest tested contrast sensitivity level]×scotoma depth (%).Results Group #1:Visus=0,43±0,18logMAR; ND=0,67±1,2; CL=10±7,04%; VLRH=2,1±3,97%; LAG=150,92±341,35%. Group #2:Visus=0,51±0,49logMAR; ND=1,4±0,55; CL=38,8±12,03%; VLRH=15,18±10,56%; LAG=32,13±20,13%.Conclusion In group #2 3D‐CTAG revealed scotomas typical for macular edema: VLRH=15,18±10,56% compared to 2,1±3,97% (p=0,05) in group #1 and LAG=32,13±20,13% compared to 150,92±341,35% (p=0,05) in group #1. Observed functional disorders show that 3‐fold injection of Ranibizumab, adopted as the standard, appears to be insufficient in 45,45% of the cases. 3D‐CTAG may be an effective method for self‐monitoring the recurrence of macular edema in wet AMD patients. Commercial interest

Method for comparative evaluation of therapeutic efficacy in dry AMD patients using 3D‐CTAG

AbstractPurpose Evaluation of therapeutic efficacy in dry AMD patients using 3DComputer‐automated Threshold Amsler Grid testing (3D‐CTAG; Fink &amp;Sadun, 2004).Methods Dry AMD patients (n=87, 174 eyes). Group#1 (n=29): 200 mg Docosahexaenoic Acid (DHA) and 300 mg Eicosapentaenoic Acid (EPA). Group #2 (n=29): Lutein (12 mg) and Zeaxanthin (0,5 mg). Controls (n=29). 3D‐CTAG testing after 3 months of treatment.Indices: number of VF defects per eye (ND),lowest perceivablecontrast level (CL), absolute volume lost (AVL), VF volume lost relative to hill‐of‐vision (VLRH).Results Group#1: ND=0,31±0,54 (before) down to 0,16±0,37(after treatment); CL=12,31±8,03% down to 10,9±7,21%; VLRH=1,2±1,14% down to 0,26±0,52%.Group#2: ND=0,29±0,5 down to 0,21±0,41; CL=11,72±12,79% down to 9,66±10,2%; VLRH=1,01±0,88% down to 0,68±1,14%. Controls: ND=0,29±0,5 up to 0,34±0,51; CL=13,79±8,65% up to 14,38±10,38%; VLRH=0,93±0,9% up to 1,22±1,21%.Conclusion We demonstrated with 3D‐CTAG a decrease of VLRH of 0,94% (p=0,01) in group#1 after 3 months DHA/EPA treatment compared to 0,33% (p=0,05) in group#2, and an increase of VLRH of 0,29% (p=0,01) in the controls. This seems to indicate that DHA/EPA treatment of dry AMD may be more effective than Lutein‐Zeaxanthin therapy. Commercial interest

Distinguishing wet from dry age-related macular degeneration using three-dimensional computer-automated threshold Amsler grid testing

Background/aimsWith the increased efficacy of current therapy for wet age-related macular degeneration (AMD), better ways to detect wet AMD are needed. This study was designed to test the ability of...

Novel 3D Computer-Automated Threshold Amsler Grid Visual Field Testing of Scotomas in Patients with Glaucoma

Three-dimensional (3D) computer-automated threshold Amsler grid testing was used to identify and characterize scotomas typical of glaucoma. The 3D test exhibits a grid on a computer screen at a preselected grayscale and angular resolution, and allows patients to trace those areas on the grid that are missing in their visual field using a touch screen. Eleven eyes in patients with an established diagnosis of glaucoma were examined according to the above protocol. A total of 23 eyes from normal subjects were used as controls. The 5-minute test required that patients repeatedly outline scotomas on a touch screen with varied displays of contrast while maintaining their gaze on a central fixation marker. A 3D depiction of the visual field defects was then obtained that was further characterized by the location, shape, extent, depth, and slope of the scotomas. In this pilot study, the 3D depiction of visual field loss demonstrated paracentral, superior and inferior altitudinal, and nasal step defects consistent with glaucomatous damage. The 3D depiction showed a shape, extent, depth, and slope that are consistent with the severity of damage. The 3D test identified and characterized scotomas typical of glaucoma. The test provides several advantages over conventional perimetry including additional information through 3D depiction of scotomas with the addition of contrast sensitivity and a higher angular/spatial resolution. Improved patient compliance and reliability through shorter testing time and potential interactive accessibility and distribution over the Internet further characterize the test.

Quantitative analysis of central visual field defects in macular edema using three-dimensional computer-automated threshold Amsler grid testing

To evaluate the central visual field (CVF) with specialized Amsler grid testing methods that include contrast sensitivity evaluation, in an attempt to detect abnormalities not identified with standard methods and to define new patterns of CVF deficits in two different diseases. 3D computer-automated threshold Amsler grid testing (3D-CTAG) was performed at five levels of contrast in one eye of 37 patients with diabetic macular edema (DME, n = 16) and exudative age-related macular degeneration (AMD, n = 21). 3D-CTAG abnormalities were detected in six patients (16%) who had no abnormalities with conventional Amsler grid testing. DME patients had more foci of CVF deficits (3.56 +/- 2.92 defects/eye), than AMD patients (1.24 +/- 0.89 defects/eye; P < 0.0002). The shape of the 3D-CTAG abnormality in DME was an inverted cone, while the deficits in AMD were always cylindrical. All eyes showed significant increases in CVF deficit surface area at minimum contrast levels when compared to maximum contrast (295% greater with DME, P < 0.02 and 150% greater with AMD, P < 0.03). 3D-CTAG detected CVF abnormalities not identified with conventional Amsler grid testing in 16% of subjects. Low-contrast conditions elicited a larger defect in both DME (3-fold) and AMD (1.5-fold). DME and AMD have unique 3D-CTAG profiles, enabling diagnostic discrimination. Measuring CVF defects with 3D-CTAG can quantitatively index disease severity and may be useful in longitudinal studies of the natural history of disease, as well as providing a quantitative outcome measure of the response to therapy.

Characterizing ethambutol‐induced optic neuropathy with a 3D computer‐automated threshold Amsler grid test

Characterizing ethambutol‐induced optic neuropathy with a 3D computer‐automated threshold Amsler grid test

Early detection of glaucoma by means of a novel 3D computer-automated visual field test

Purpose:A recently devised 3D computer-automated threshold Amsler grid test was used to identify early and distinctive defects in people with suspected glaucoma. Further, the location, shape and depth of these...

SCOTOMAS OF AGE-RELATED MACULAR DEGENERATION DETECTED AND CHARACTERIZED BY MEANS OF A NOVEL THREE-DIMENSIONAL COMPUTER-AUTOMATED VISUAL FIELD TEST

We used the recently devised three-dimensional computer-based threshold Amsler grid test to acquire and identify typical patterns of visual field defects (scotomas) caused by age-related macular degeneration (AMD). Patients with AMD traced on a computer touch screen the borders of those areas on an Amsler grid that were missing from their field of vision. Scotomas were repeatedly outlined and recorded at different grid contrast levels. The resulting three-dimensional "hole" in the central 25 degrees of the visual field was further characterized by its slope, location, shape, and depth. The results were compared with fundus photographs and fluorescein angiograms. Twenty-five patients and 41 eyes were examined. The three-dimensional depictions consistently demonstrated central scotomas with "scallop"-shaped borders and steplike patterns, with either steep slopes or a combination of steep and shallow slopes. The steep slopes corresponded to nonexudative AMD, while the shallow slopes indicated exudative AMD. The three-dimensional computer-automated threshold Amsler grid test may demonstrate characteristic scotoma patterns in patients with AMD that conform to the respective fluorescein angiograms. The test shows promise as an effective tool in accurately evaluating, characterizing, and monitoring scotomas in patients with AMD. It may have the potential as a screening tool for the early diagnosis of AMD.

Validity and Interpretation of Amsler Grid Reports

To compare the reports of scotomas and metamorphosia in standard and threshold Amsler grid testing with the location and extent of scotomas in the macular region as determined by standard and threshold fundus perimetry. Fundus perimetry determined the existence, size, and retinal location of macular scotomas. Amsler grid testing was performed with the scanning laser ophthalmoscope and the TA-300 system (Stereo Optical, Chicago, Ill). All testing was done at both standard and threshold light conditions. Fifty-five patients with vision loss in the macular region and 10 normally sighted subjects. Nearly half of the standard and threshold scotomas were not detected by Amsler grid testing. For scotomas of 6 degrees or less in diameter, 77% of standard and 87% of threshold scotomas were not detected by Amsler grid testing. Of the eyes with central scotomas involving the fovea, 66% used an eccentric preferred retinal locus for fixating the center of the grid. Finally, more than half of the distortion reported in Amsler grids was at the retinal area that corresponded to the scotoma area, not a nonscotoma retinal area. Amsler grid reports have poor validity and cannot be accurately interpreted for use in the clinical diagnosis of retinal defects.

Threshold Amsler grid testing in diabetic retinopathy

The Amsler grid is a suprathreshold target used to assess the central 10 degrees of the visual field; thus, it may fail to detect relative central scotomas. Low luminance conditions can be created by viewing the white grid on a black background through two cross-polarizing filters that vary light transmission and change the procedure to a threshold Amsler grid (TAG) test, thereby increasing its sensitivity. A total of 26 patients with diabetic retinopathy were tested by standard Amsler grid, TAG, and tangent screen. Four scotomas were detected by Amsler grid testing; each of these scotomas expanded in size on retesting with the TAG. TAG testing revealed 22 scotomas more than five times the number seen with conventional Amsler grid testing; tangent-screen examination confirmed 9 of these defects. In many cases, fundus photography and fluorescein angiography revealed pathology that correlated with the scotomas detected only by TAG testing. It thus appears that the TAG test is a rapid, high-yield, and sensitive means of assessing the central visual field in patients with diabetic retinopathy.

Threshold Amsler Grid Testing in Maculopathies

The Amsler grid is a suprathreshold target and thus may fail to detect relative scotomas. If the grid is viewed through two cross-polarizing filters creating low luminance conditions (threshold Amsler grid testing) the test is far more sensitive. Ten patients with disorders of the macula with normal standard white Amsler grid testing were studied with three other Amsler grid tests. Of the 15 involved eyes, 12 had visual field defects present with threshold Amsler grid testing. Tangent screen examination showed defects in 10 of these 12 eyes. The two red grids used were not as sensitive as the threshold grid. Three eyes had metamorphopsia with the white grid which became the site of a visual field defect with threshold testing. Threshold Amsler grid testing is a rapid and sensitive technique for the evaluation of the central 10° of visual field in patients with maculopathies.

Threshold Amsler grid testing. Cross-polarizing lenses enhance yield.

The Amsler grid is a commonly used test for evaluation of the 10 degrees of visual field surrounding fixation. The Amsler grid is a suprathreshold stimulus and thus may not detect relative scotomas. Therefore, we had ten patients with optic neuropathies view the grid through cross-polarizing filters that created low luminance conditions in which the grid was barely perceptible. The patients were also surveyed with a 2-m tangent screen protocol and threshold automated perimetry. The threshold Amsler grid technique increased both the number of defects found and the total area of these defects by approximately a factor of 5. Two thirds of the defects found were confirmed by one of the other screening techniques. Threshold Amsler grid testing is a rapid, inexpensive, and sensitive technique for the evaluation of the central 10 degrees of the visual field.