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Color and contrast-specific perimetry to probe retinal ganglion cell subtype vulnerability · Glaucoma, Vision & Longevity: Supplements & Science

• 0:00
  SPEAKER_00: Introduction.
• 0:01
  SPEAKER_00: Vision relies on many kinds of retinal ganglion cells, RGCs, each tuned to different color or contrast signals.
• 0:07
  SPEAKER_00: Standard visual field tests use white-on-white, achromatic stimuli and measure overall sensitivity, but early or selective damage in diseases like glaucoma can hide behind normal full field results.
• 0:19
  SPEAKER_00: Specialized perimetry tests now probe specific pathways by using color or temporal contrast stimuli.
• 0:26
  SPEAKER_00: For example, blue-on-yellow perimetry, short wavelength automated perimetry, swap, presents a bright blue target on a yellow background to isolate the short wavelength, blue cone pathway and its small but stratified RGCs.
• 0:40
  SPEAKER_00: Similarly, red-green, chromatic tests aim at the long, medium wavelength cone pathways, parvocellular system, and flicker temporal tests like frequency doubling perimetry or high-frequency flicker, stress the large parasol, magnocellular RGCs.
• 0:55
  SPEAKER_00: By dissecting vision in this way, clinicians hope to catch damage in specific RGC subtypes earlier or more precisely than with white-on-white testing.
• 1:05
  SPEAKER_00: This article reviews these color and contrast-specific perimetry methods and how they relate to glaucoma and optic nerve disease.
• 1:13
  SPEAKER_00: We discuss what blue-yellow and red-green perimetry can reveal about pathway dysfunction, how flicker perimetry examines temporal contrast processing, and how these functional losses map onto structural imaging, OCT, and blood flow metrics, OCT angiography.
• 1:30
  SPEAKER_00: We also consider evidence on whether such targeted tests predict later decline on standard fields and suggest practical testing protocols that maximize diagnostic insight without overly straining patients.
• 1:42
  SPEAKER_00: Color and contrast-specific perimetry, blue-yellow swap.
• 1:46
  SPEAKER_00: Perimetry blonde yellow perimetry swap is a well-known color test.
• 1:50
  SPEAKER_00: It uses a large, narrow band blue stimulus, around 440 nanometers, presented on a bright yellow background.
• 1:58
  SPEAKER_00: The high luminance yellow field adapts the red and green cones so that the remaining pathway, the short wavelength, blue cones, and their small bastratified RGCs, respond mainly.
• 2:08
  SPEAKER_00: In effect, swap isolates the blue cone channel.
• 2:11
  SPEAKER_00: Early glaucoma often affects these small basstratified cells, so swap can reveal field loss sooner than conventional testing.
• 2:19
  SPEAKER_00: Indeed, studies report swap can detect visual field defects in glaucoma suspects or early glaucoma eyes before standard perimetry shows losses, suggesting higher sensitivity for early damage.
• 2:32
  SPEAKER_00: For example, one study found swap deficits strongly correlated with retinal nerve fiber thinning in the inferior quadrant in glaucoma patients, indicating swap loss matches structural damage.
• 2:45
  SPEAKER_00: However, swap has practical limitations.
• 2:48
  SPEAKER_00: It is sensitive to lens opacity, cataracts make results unreliable, and generally requires longer testing to overcome adaptation effects.
• 2:56
  SPEAKER_00: Clinically, swap often uses a CETA-swap algorithm to shorten time, but patients may still fatigue easily.
• 3:04
  SPEAKER_00: In research, swap fields have shown greater mean deficits than white-on-white fields in glaucoma suspects, but reproducibility can be an issue.
• 3:12
  SPEAKER_00: Another swap-based approach measures pupil responses, pupillography, to blue versus yellow stimuli, reflecting melanopsin ganglion cell function.
• 3:22
  SPEAKER_00: One study found blue light pupillary tests detected early loss slightly better than yellow light stimuli in mild glaucoma, hinting that blue pathway testing may reveal early damage.
• 3:33
  SPEAKER_00: Given swap strengths and weaknesses, it is mainly used when clinicians suspect early glaucoma or optic neuropathy, despite normal standard fields.
• 3:42
  SPEAKER_00: Many glaucoma specialists run a blue-on-yellow Swedish interactive threshold algorithm, Ceta SWAP, in suspicious cases.
• 3:49
  SPEAKER_00: Red-green parvocellular perimetry.
• 3:52
  SPEAKER_00: The red-green pathway, parvocellular system, carries high-resolution and color opponent signals and can also be tested psychophysically.
• 4:00
  SPEAKER_00: In practice, isolating this channel requires careful design, often using isoluminant red versus green stimuli.
• 4:07
  SPEAKER_00: There is no widely used commercial red-green perimetry, but research tests have shown interesting findings.
• 4:14
  SPEAKER_00: For example, studies using red-green opponency testing have found that in some glaucomatous eyes, the parvocellular pathway is as vulnerable or even more vulnerable than the acromatic pathway.
• 4:26
  SPEAKER_00: One classic study found that a subset of early glaucoma eyes had larger losses for red-green color contrast than for white-on-white vision.
• 4:34
  SPEAKER_00: This suggests that parvocellular LM cone ganglion cells can be selectively damaged.
• 4:41
  SPEAKER_00: In that study, red-green contrast thresholds in some patients were unexpectedly worse than predicted by overall sensitivity, implying a departure from the usual assumption that large magnocellular fibers would show equal or greater loss.
• 4:55
  SPEAKER_00: Because true isoluminant red-green perimetry is complex, some clinics have tried simpler variants.
• 5:01
  SPEAKER_00: For instance, a green-on-yellow test using a green target on yellow background mimics a red-green contrast test with the yellow background suppressing blue cones.
• 5:12
  SPEAKER_00: A recent study showed that green-on-yellow fields agreed well with traditional blue-on-yellow fields, with similar sensitivity and specificity for glaucoma detection.
• 5:22
  SPEAKER_00: In practice, this means clinicians can probe parvocellular function by switching stimulus wavelength, but with current equipment, this is uncommon.
• 5:31
  SPEAKER_00: However, it highlights that color opponent deficits, both red-green, and blue-yellow, provide complementary information.
• 5:38
  SPEAKER_00: Swap tests the conia cellular S-cone root, and a green-yellow test probes the LM parvo route.
• 5:45
  SPEAKER_00: Temporal flicker, contrast perimetry.
• 5:48
  SPEAKER_00: Temporal contrast sensitivity, the ability to detect rapid flicker or motion, is largely carried by the magnocellular, M-cell pathway.
• 5:56
  SPEAKER_00: Tests that measure flicker perception, flicker perimetry, or that exploit the frequency doubling illusion both stress these fast pathways.
• 6:04
  SPEAKER_00: In flicker perimetry, patients detect light-dark alternations at various frequencies and contrasts.
• 6:11
  SPEAKER_00: In frequency doubling technology, FT perimetry, a grading flickers at high rate, e.g.
• 6:16
  SPEAKER_00: 25 Hz, creating an illusion of doubled spatial frequency.
• 6:20
  SPEAKER_00: This preferentially stimulates the parasol M ganglion cells in the retina.
• 6:25
  SPEAKER_00: Studies have shown that glaucoma affects high-frequency flicker sensitivity.
• 6:29
  SPEAKER_00: Early work by Tyler reported that many glaucoma patients and ocular hypertensives had deficits for rapid flicker.
• 6:37
  SPEAKER_00: Later reviews noted that aging also reduces high-frequency flicker vision, but even after accounting for age, glaucoma patients show a robust reduction in flicker sensitivity.
• 6:47
  SPEAKER_00: Notably, critical flicker fusion, CFF perimetry, which finds the highest refresh rate a person can detect, has been found superior to standard white-on-white perimetry in detecting glaucomatous damage.
• 7:00
  SPEAKER_00: In other words, testing how fast a light can flicker before blending into steady light can reveal loss of function that normal fields miss.
• 7:09
  SPEAKER_00: FDT perimetry is already used clinically as a glaucoma screen.
• 7:13
  SPEAKER_00: Correlation studies show that FDT results align moderately with structural loss.
• 7:19
  SPEAKER_00: One analysis found FDT sensitivity and OCT measured RNFL thickness were significantly correlated, Spearman Arbor 0.65, across all glaucoma patients.
• 7:29
  SPEAKER_00: In practice, FDT is quick, a screening test takes a few minutes per eye, and has demonstrated good early detection ability.
• 7:36
  SPEAKER_00: More recent matrix FDT devices use full thresholding and can track progression.
• 7:41
  SPEAKER_00: A prospective study followed ocular hypertensive glaucoma suspect eyes for three years with matrix FDT and conventional perimetry.
• 7:50
  SPEAKER_00: It found that more eyes developed visual field defects on FDT 8.2%.
• 7:57
  SPEAKER_00: Importantly, the study concluded that FDT often detected defects that were not evident on SAP at the same visits.
• 8:03
  SPEAKER_00: In summary, temporal contrast tests, Flicker, CFF, FDT, are sensitive to early glaucoma and provide a complementary view of vision loss.
• 8:12
  SPEAKER_00: Mapping functional loss to structure, OCT-OCT angio.
• 8:16
  SPEAKER_00: Structural OCT imaging of the retina and optic nerve has revolutionized glaucoma care.
• 8:21
  SPEAKER_00: Retinal nerve fiber layer, RNFL, thickness, and the ganglion cell complex, GCC, in the macula, ganglion cell plus interplexiform layers, are closely linked to functional loss.
• 8:32
  SPEAKER_00: Studies comparing color perimetry to OCT measures show consistent structure-function matches.
• 8:38
  SPEAKER_00: For example, in eyes with glaucoma, the retinal nerve fiber layer thickness correlated significantly with swap results, especially in the inferior quadrant, and overall RNFL thinning paralleled decreases in blue-yellow sensitivity.
• 8:52
  SPEAKER_00: In one series, average RNFL thickness had a stronger correlation with swap mean deviation, R.39 p equals 0.001, than with white-on-white perimetry.
• 9:03
  SPEAKER_00: This suggests that loss picked up in the swap blue pathway, testing aligns with measurable nerve fiber loss.
• 9:10
  SPEAKER_00: Similarly, FDT loss has been linked to thinning of RNFL, affirming that parasite's damage shows up in OCT structure.
• 9:17
  SPEAKER_00: Optical coherence tomography and geography, OCTA, provides maps of blood vessel density beneath the retina and around the optic nerve.
• 9:25
  SPEAKER_00: Glaucoma affects retinal blood flow.
• 9:27
  SPEAKER_00: Many studies show reduced capillary density in glaucomatous eyes.
• 9:32
  SPEAKER_00: In fact, wide field vessel density measured in the RNFL layer, peripapillary OCTA, was just as diagnostic for glaucoma as RNFL thickness itself.
• 9:42
  SPEAKER_00: For distinguishing glaucoma from healthy eyes, one study found whole image RNFL vessel density gave an AUC of Tajero.94, similar to the AUC equal.92 for average RNFL thickness.
• 9:54
  SPEAKER_00: In other words, both structural loss and vascular loss are telling a similar story.
• 9:58
  SPEAKER_00: However, macular vessel density and fluency in the inner retina seems less predictive than macular thickness.
• 10:05
  SPEAKER_00: One large study found GCIPL thickness outperformed macular OCTA vessel density for separating glaucoma eyes from normals.
• 10:13
  SPEAKER_00: Clinicians can combine these findings.
• 10:15
  SPEAKER_00: Focal field losses on specific color perimetry often correspond to focal thinning or perfusion drop on imaging.
• 10:21
  SPEAKER_00: For example, an inferior arcuate defect on swap usually matches superior RNFL thinning on OCT.
• 10:28
  SPEAKER_00: OCTA can add further detail.
• 10:30
  SPEAKER_00: Areas of capillary dropout often align with the most damaged sectors of the nerve.
• 10:35
  SPEAKER_00: Overall, targeted perimetry abnormalities flag regions to scrutinize on OCT.
• 10:41
  SPEAKER_00: Predicting standard field decline.
• 10:43
  SPEAKER_00: A key question is whether these specialized tests can predict future loss on conventional white-on-white fields.
• 10:49
  SPEAKER_00: If so, they would be especially useful in glaucoma suspects.
• 10:53
  SPEAKER_00: The evidence is mixed.
• 10:55
  SPEAKER_00: Several long-term studies have looked at whether SWAP or FDT lead SAP in conversion to glaucoma.
• 11:02
  SPEAKER_00: One five-year study in ocular hypertension found that SWAP preceded SAP conversion in about 37% of cases, was simultaneous in 29%, and failed to convert in 34%.
• 11:13
  SPEAKER_00: In practice, the authors concluded that swap and SAP flag different subsets of early glaucoma, so using both can improve detection.
• 11:20
  SPEAKER_00: Another much larger Dutch study, 7 to 10 year follow-up of 400 eyes, found that swap almost never led SAP.
• 11:28
  SPEAKER_00: Only two out of 24 eyes showed swap conversion earlier, whereas SAP was equal or earlier in the rest.
• 11:35
  SPEAKER_00: The authors concluded SWAP did not generally predict SAP defects, and that SAP remained at least as sensitive for conversion.
• 11:44
  SPEAKER_00: These results suggest that SWAP can catch some early cases, especially in the short term, but it is not a guaranteed early warning in most eyes.
• 11:52
  SPEAKER_00: For flicker perimetry, the data is a bit more promising.
• 11:56
  SPEAKER_00: In the Prospective Matrix FDT study, new visual field defects appeared on FDT slightly more often than on SAP, 8.0%, 6.2% of eyes over 3.4 years.
• 12:07
  SPEAKER_00: The authors noted that FDT did detect some defects not yet seen on SAP.
• 12:11
  SPEAKER_00: In other words, FDT caught a few cases a bit earlier.
• 12:14
  SPEAKER_00: On the other hand, long-term predictive studies of frequency doubling perimetry are limited.
• 12:20
  SPEAKER_00: One small analysis suggested that rapid worsening on FDT perimetry was associated with faster SAP decline, but this is not yet definitive.
• 12:29
  SPEAKER_00: In summary, targeted color and flicker tests can sometimes signal trouble before standard fields.
• 12:35
  SPEAKER_00: Swap may uncover some early losses, especially in the short term, but it does not consistently outrun SAP in all patients.
• 12:43
  SPEAKER_00: FDT might reveal a modest number of earlier defects.
• 12:46
  SPEAKER_00: Therefore, these tests are best seen as complementary.
• 12:49
  SPEAKER_00: If a targeted test becomes abnormal, it raises concern even if white-on-white is still normal.
• 12:55
  SPEAKER_00: But a normal color flicker test does not guarantee stability.
• 12:59
  SPEAKER_00: Longitudinal studies suggest that both approaches should be used when possible, and field changes confirmed over multiple tests.
• 13:08
  SPEAKER_00: Practical testing protocols.
• 13:10
  SPEAKER_00: Because these specialized tests can be lengthy or fatiguing, protocols must balance thoroughness with patient comfort.
• 13:17
  SPEAKER_00: Key strategies include limiting the number of tests per visit, using faster algorithms, and tailoring the field scope.
• 13:24
  SPEAKER_00: In practice, examiners often alternate tests across visits to avoid overloading patients.
• 13:29
  SPEAKER_00: For instance, one eye's swap or FDT test might be done on one day and the other on a separate day.
• 13:36
  SPEAKER_00: Even then, clinicians usually limit sessions to two fields, either two eyes on one type of test or one eye on two modalities, and recommend waiting at least a week before retesting the same eye on a different test.
• 13:49
  SPEAKER_00: This spacing helps avoid confusion from fatigue or learning effects.
• 13:53
  SPEAKER_00: Modern perimeters offer faster algorithms, e.g., CETA strategies, that can be used for color perimetry, having test time.
• 14:01
  SPEAKER_00: Whenever possible, using a threshold strategy rather than a full threshold template reduces test duration.
• 14:08
  SPEAKER_00: Limiting the test area can also help.
• 14:10
  SPEAKER_00: If a patient has a known deficit, e.g., superior defect, focusing additional colored stimuli in that region will save time versus retesting the whole field.
• 14:20
  SPEAKER_00: Larger stimulus sizes, Goldman size V, are often used in swap or flicker tests to improve reliability and speed.
• 14:28
  SPEAKER_00: Patient factors matter too.
• 14:30
  SPEAKER_00: Good lens clarity is essential for color tests.
• 14:32
  SPEAKER_00: Cataract can invalidate swap up, so many protocols require lens grading or exclude advanced cataracts.
• 14:39
  SPEAKER_00: Patients should be well rested and alert.
• 14:41
  SPEAKER_00: Scheduling these exams at times of day when the patient is attentive can reduce fatigue.
• 14:46
  SPEAKER_00: In some, an effective protocol might look like.
• 14:50
  SPEAKER_00: Baseline, white-on-white perimetry and OCT.
• 14:53
  SPEAKER_00: If suspicious or borderline, schedule a color or flicker perimetry using CETA or short exam mode.
• 14:59
  SPEAKER_00: Perform no more than two fields per visit, and allow a week between different tests for one eye.
• 15:05
  SPEAKER_00: If a targeted test shows a suspect defect, follow with OCT, OCTA imaging of that region, or more focused perimetry at the next appointment.
• 15:14
  SPEAKER_00: For screening or busy clinics, it may be practical to alternate specialized tests, for example, do swap one year, FDT the next, rather than all tests every year.
• 15:24
  SPEAKER_00: The goal is to gather pathway-specific data without doubling clinic visits or overwhelming the patient.
• 15:30
  SPEAKER_00: Conclusion.
• 15:31
  SPEAKER_00: Color-specific, blue-yellow, red-green, and contrast-specific flicker perimetry enrich our view of visual function by probing the parvocellular, coniocellular, and magnocellular RGC pathways separately.
• 15:44
  SPEAKER_00: Blue-yellow swap tests the S-cone bistratified pathway and often reveals early glaucomatous loss correlating with RNFL thinning.
• 15:52
  SPEAKER_00: Red-green testing, less commonly used clinically, can expose LM-cone midget pay deficits.
• 15:59
  SPEAKER_00: Studies have found cases where red-green color vision declines were unexpectedly worse than acromatic losses.
• 16:05
  SPEAKER_00: Temporal flicker perimetry targets the parasol M cell system and has proven sensitive for incipient glaucoma, sometimes outperforming standard tests.
• 16:14
  SPEAKER_00: Structural OCT and OCTA provide an anatomical map to match these functional findings.
• 16:20
  SPEAKER_00: Regions of color-specific field loss tend to coincide with thinning of the corresponding retinal layers and with microvascular dropout.
• 16:29
  SPEAKER_00: While color and flicker tests may predict some impending white-on-white field loss, their performance is not perfectly consistent.
• 16:37
  SPEAKER_00: Some long-term studies found swap rarely preceded standard field loss, whereas flicker perimetry showed a slight lead in many cases.
• 16:46
  SPEAKER_00: In practice, using these tests judiciously, spacing them out, focusing on areas of concern, and confirming any deficits allows clinicians to capture early or pathway-specific damage without excessive testing burden.
• 17:00
  SPEAKER_00: Incorporating color and contrast perimetry alongside structural OCT-OCTA offers a multimodal approach.
• 17:07
  SPEAKER_00: For patients, this means problems might be detected by tests of color or flicker vision even if standard vision still seems normal.
• 17:15
  SPEAKER_00: For clinicians, the challenge is selecting the right test for each case and managing the added testing time.
• 17:21
  SPEAKER_00: By following protocols that limit fatigue and redundancy, one can gain the specificity of these tests while keeping exams practical.
• 17:29
  SPEAKER_00: In the end, swap, red-green contrast tests, and flicker perimetry are tools, and like all tools, they work best when used as part of an overall diagnostic strategy that includes imaging and regular follow-up.
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  SPEAKER_00: You can find the full article at visualfieldtest.com.
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  SPEAKER_00: Thanks for listening.
• 19:49
  SPEAKER_00: To check your visual field, click the link at the bottom of this article or visit visualfieldtest.com.