Visual Psychophysics in Diabetic Retinopathy |
77 |
was no difference in CS function between diabetics without retinopathy and controls, whereas Ghafour et al. [71], using the same test, found that diabetics without retinopathy were abnormal at 3.2 and 6.3 c/deg. Using the Vision Contrast Test System in patients with little or no retinopathy, Trick et al. [69] found reduced mean CS at each spatial frequencies when compared to controls; however, a post hoc analysis yielded no statistical difference between the groups. Sokol et al. studied separately insulinand non-insulin- dependent diabetes mellitus (IDDM and NIDDM) patients and found that patients with IDDM and no DR had normal CS function, whereas patients with NIDDM, normal VA, and no DR had abnormal CS at high spatial frequencies. If background retinopathy was present, abnormal CS at all spatial frequencies was found [73]. Della Sala et al. [72], using the Cambridge low-contrast sensitivity charts, showed abnormal CS in 9 of 22 patients without diabetic retinopathy and in only 6 of 20 patients with background retinopathy (Table 2). Therefore, the contrast sensitivity losses in IDDM and NIDDM patients may not be similar, and further studies are needed to substantiate this hypothesis. Contrast sensitivity testing, as color vision testing, shows significant changes in diabetics and there is some correlation with glycemic control, although prospective studies are required to assess this relationship over a longer time period. Although both tests show similar patterns in diabetics, direct comparisons of the two tests seem to indicate the CS function test as more sensitive and specific.
MACULAR RECOVERY FUNCTION (NYCTOMETRY)
Macular recovery function (nyctometry) is a dynamic measure of the initial 2-min course of macular recovery function following preadaptation to a strong uniform illumination of a large area of the retina. It is a standardized technique, which lasts only 6.5 min. It quantifies not only the dark adaptation of the cone system but also the macular sensitivity to glare [79]. Gliem and Schulze reported a progressive reduction in macular recovery related to deterioration of DR [80]. Midena et al. [79] showed, in a well-defined series of patients, that reduced nyctometry is directly and strongly related to the progression of retinal (functional and anatomical) derangement due to diabetes mellitus. Different authors suggested, but never definitively proved, that nyctometry can be used to predict the progression of background DR to proliferative DR. They suggested the use of nyctometry as a screening method in selecting patients at high risk for proliferative DR [81–83]. Verrotti et al. [84] found altered nyctometry in microalbuminuric diabetic children vs. normoalbuminuric and normal controls. Reported values were independent of both the level and the fluctuations of glycemia. However, Lauritzen et al. [85] found improved performance of nyctometry in the first year in patients on a intensive insulin regimen. In two separate studies, Andersen et al. [86] and Frost-Larsen et al. [87] found significant improvement in macular recovery function in newly diagnosed juvenile diabetics after a 10-day period of superregulation in the biostator. This indicates that in metabolic dysregulation, the results of nyctometry are reversible to a certain extent provided the reduced values of nyctometry are mainly due to functional changes in the retina [83].
In CSME, 1 week after macular laser photocoagulation, nyctometry was shown to decrease significantly, followed by slow improvement toward the initial value [76].
Table 2. Studies which have investigated contrast sensitivity in patients with diabetic retinopathy
Principal |
|
|
|
|
|
|
investigator/ |
Types |
|
Age in years: |
|
|
|
year of publication |
of study |
Sample size |
mean/range |
DR status and VA |
Nature of stimulus |
Conclusions |
|
|
|
|
|
|
|
Ghafour et al. [71] |
Case-control Cases-93 |
Cases-47 (27–70) |
42-No DR |
Arden grating test |
Diabetic pts without DR |
|
|
|
Controls-80 |
Controls-46 (24–68) |
22-Background DR |
|
have increased thresh- |
|
|
|
|
29-PDR |
|
olds at the higher spatial |
|
|
|
|
VA: 6/5 to 6/36 |
|
frequencies. Significative |
|
|
|
|
|
|
difference CS threshold |
|
|
|
|
|
|
found between each |
|
|
|
|
|
|
group (controls-no |
|
|
|
|
|
|
DR-background-PDR) |
Hyvärinen et al. |
Case-control Cases-19 |
Cases-32 (19–59) |
5-Micro±hemorrhages |
Sinusoidal grating |
CS seems to correlate better |
|
[3] |
|
Controls-from |
|
but normal vision |
(cathode-ray- |
with DR status then with |
|
|
Virsu et al. |
|
(20/20) |
display) |
VA. Diabetic pts without |
|
|
[127] |
|
5-bDR |
|
DR has no significant |
|
|
|
|
6-PDR |
|
reduction of CS in com- |
|
|
|
|
3-PDR + central cataract |
|
parison to normal sub- |
|
|
|
|
|
|
jects. In the third group |
|
|
|
|
|
|
(cataract) CS was better |
|
|
|
|
|
|
than expected |
Regan and Neiman |
Case-control Cases-15 |
Cases-49 (24–75) |
6-VA ³6/7.5 or better |
Regan chart |
Diabetic pts had significa- |
|
[128] |
|
Controls-40 |
|
9-VA <6/7.5 |
|
tive CS loss |
Sokol et al. [73] |
Case-control Cases-64 |
– |
31-IDDM and no DR; |
Sinusoidal grating |
Pts with NIDDM, normal |
|
|
|
Controls-117 |
|
VA: 20/25 or better |
(microproces- |
VA and no DR had |
|
|
|
|
33-NIDDM and no |
sor-controlled |
abnormal CS at high |
|
|
|
|
(n = 16) or back- |
video system) |
spatial frequencies. Pts |
|
|
|
|
ground (n = 17) DR; |
|
with NIDDM and bDR |
|
|
|
|
VA: 20/30 or better |
|
had abnormal CS at all |
|
|
|
|
|
|
spatial frequencies. Pts |
|
|
|
|
|
|
with IDDM and no DR |
|
|
|
|
|
|
had normal CS |
Della Sala et al. |
Case-control |
Cases-42 |
Cases-12–75 |
22-No DR |
Cambridge |
Diabetic pts showed |
[72] |
|
Controls-84 |
Controls-14–68 |
19-bDR |
low-contrast |
decreased CS |
|
|
|
|
1-PDR |
sensitivity |
|
|
|
|
|
VA: 1.0 or better |
charts |
|
Trick et al. [69] |
Case-control |
Cases-57 |
No DR-36.9 ± 11.1 |
37-No DR |
Vistech VCTS |
All diabetic pts showed |
|
|
Controls-35 |
bDR-37.9 ± 8.6 |
20-bDR |
6500 distance |
decreased CS, par- |
|
|
|
Controls-33.3 ± 9.3 |
18-NIDDM |
chart |
ticularly with mid-spatial |
|
|
|
|
39-IDDM |
|
frequency gratings. |
|
|
|
|
VA: 20/30 or better |
|
No difference between |
|
|
|
|
|
|
IDDM and NIDDM pts |
Khosla et al. [129] |
Case-control |
Cases-38 eyes |
No DR-50.0 ± 11.8 |
22 (eyes)-No DR |
Cambridge low- |
Significant decreased CS in |
|
|
(22 pts) |
bDR-47.1 ± 10.3 |
16-bDR |
contrast sensi- |
the retinopathy group. |
|
|
Controls-20 |
Controls-47.2 ± 13.5 |
VA: 6/6 |
tivity charts |
No significant difference |
|
|
eyes (10 |
|
|
|
in CS between non retin- |
|
|
pts) |
|
|
|
opathy group and normal |
|
|
|
|
|
|
subjects |
Midena et al. [76] |
Prospective |
30 Diabetic |
55 (40–70) |
Minimalto mild-bDR |
Arden grating test |
CS improved after photo- |
|
non com- |
pts |
|
CSME |
|
coagulation, with a sig- |
|
parative |
|
|
VA: 1.0 |
|
nificant difference after |
|
study |
|
|
|
|
3 months, but did not |
|
|
|
|
|
|
reach normal values |
Bangstad et al. |
Case-control |
Cases-30 pts |
Micro-albuminuria |
Micro-albuminuria |
Vistech VCTS |
Micro-albuminuric pts |
[130] |
|
with micro- |
group: 19 (14–29) |
group: |
6500 distance |
showed worse CS at |
|
|
albuminuria |
Normo-albuminuria |
12 pts-No DR |
chart |
middle and high spatial |
|
|
Controls-27 |
group: 19 (14–24) |
18 pts-bDR |
|
frequencies, but signifi- |
|
|
pts with |
|
Normo-albuminuria |
|
cantly only for 18 cpd |
|
|
normo- |
|
group: |
|
|
|
|
albuminuria |
|
12 pts-no DR |
|
|
|
|
|
|
15 pts-bDR |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
(continued) |
Table 2. (continued)
Principal |
|
|
|
|
|
|
investigator/ |
Types |
|
Age in years: |
|
|
|
year of publication |
of study |
Sample size |
mean/range |
DR status and VA |
Nature of stimulus |
Conclusions |
|
|
|
|
|
|
|
Arend et al. [75] |
Case-control |
Cases-20 pts |
Cases-42 ± 12 |
6-No DR |
CSV-1000 (Vector |
Diabetic pts had signifi- |
|
|
Controls- |
|
8-Only microaneurisms |
vision; Dayton, |
cantly lower CS at 6 and |
|
|
Normal |
|
4-Mild retinopathy |
OH) |
12 c/deg than control |
|
|
subjects |
|
1-Severe retinopathy |
|
subjects. Foveal avascu- |
|
|
from data- |
|
1-PDR |
|
lar zone and perifoveal |
|
|
base (arch |
|
VA: 20/25 or better |
|
intercapillary area cor- |
|
|
ophth |
|
|
|
related significantly with |
|
|
75;610) |
|
|
|
CS at 12 cpd |
De Marco [131] |
Case-control Cases-66 |
Cases: |
No DR |
Conel CST auto- |
No difference was found |
|
|
|
IDDM |
30–10 ± 1.22 years |
VA: 1.0 or better |
matic (Roma, |
between diabetic aretino- |
|
|
Controls-66 |
36–16.07 ± 2.3 |
|
ITA) (sinusoi- |
patic pts and controls. |
|
|
|
years |
|
dal gratings) |
CS was not correlated |
|
|
|
Controls: |
|
|
with sexual maturity or |
|
|
|
30–9.93 ± 2.02 |
|
|
duration of diabetes |
|
|
|
years |
|
|
|
|
|
|
36–17 ± 3.16 years |
|
|
|
Verrotti et al. |
Case-control |
Cases-40 + 20 |
Cases-16.9 ± 4.9 |
20-No DR |
CSV-1000 (Vector |
Diabetic pts showed a sig- |
[132] |
|
Controls-20 |
Controls-16.9 ± 4.6 |
30-bDR |
vision; Dayton, |
nificative decrease of |
|
|
|
|
10-Preproliferative/PDR |
OH) |
CS at 12 and 18 c/deg; |
|
|
|
|
|
|
preproliferative and PDR |
|
|
|
|
|
|
pts had decreased CS at |
|
|
|
|
|
|
all frequencies, and sig- |
|
|
|
|
|
|
nificative lower than CS |
|
|
|
|
|
|
of aretinopathic pts |
Mackie et al. [133] |
Case-control |
Cases-90 |
Cases: |
VA: 0.3 or better |
Pelli–Robson |
There was a progressive |
|
|
|
Controls-50 |
Young pts- |
|
chart |
reduction of CS thresh- |
|
|
|
|
33.2 ± 7.9 |
|
|
old through the five |
|
|
|
|
Older pts- |
|
|
groups of diabetic pts (no |
|
|
|
|
65.5 ± 8.2 |
|
|
DR, bDR, PPR, treated |
|
|
|
|
Controls: |
|
|
retinopathy, treated mac- |
|
|
|
|
Young pts- |
|
|
ulopathy), significative |
|
|
|
|
30.8 ± 7.9 |
|
|
between groups in which |
|
|
|
|
Older pts- |
|
|
there was a difference |
|
|
|
|
66.6 ± 10.1 |
|
|
of at least two adjacent |
|
|
|
|
|
|
|
degrees of retinopathy. |
|
|
|
|
|
|
|
No significative differ- |
|
|
|
|
|
|
|
ence was found between |
|
|
|
|
|
|
|
controls and aretino- |
|
|
|
|
|
|
|
pathic pts |
|
Lövestam-Adrian |
Case control |
Cases-20 |
Cases-32 (15–27) |
Cases-Treated PDR or |
Precision Vision |
Pts treated with panretinal |
|
et al. [134] |
|
Controls-19 |
Controls-30 (20–42) |
severe NPDR; VA: |
chart (Preisler |
photocoagulation had |
|
|
|
|
|
0.9 (0.4–1.0) |
instrument AB, |
significative higher |
|
|
|
|
|
Controls-No DR or non |
Illinois, USA) |
contrast threshold than |
|
|
|
|
|
treated mild bDR; |
|
untreated diabetic pts |
|
|
|
|
|
VA: 1.0 (0.5–1.0) |
|
|
|
Talwar et al. [77] |
Prospective |
14 Eyes with |
47–60 years |
CSME |
Cambridge low- |
The CS improved signifi- |
|
|
noncom- |
untreated |
|
VA: 0.49 (1.0–0.1) |
contrast sensi- |
cantly after photocoagu- |
|
|
parative |
CSME |
|
|
tivity charts |
lation treatment |
|
|
study |
|
|
|
|
|
|
Stavrou et al. |
Case-control |
Cases-20 pts |
Cases-62.67 ± 11.21 |
12-No/minimum DR |
Pelli–Robson |
CS was lower in diabetic |
|
[135] |
|
Controls- |
Controls-67.36 ± 7.35 |
4-Mild DR |
chart |
pts than CS of controls, |
|
|
|
24 pts |
|
4-Moderate/severe DR |
|
but significative differ- |
|
|
|
|
|
VA: 6/9.5 or better |
|
ence was observed only |
|
|
|
|
|
8 Pts had macular |
|
between no/minimum |
|
|
|
|
|
edema |
|
DR group and controls. |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
(continued) |
|
Table 2. (continued)
Principal |
|
|
|
|
|
|
investigator/ |
Types |
|
Age in years: |
|
|
|
year of publication |
of study |
Sample size |
mean/range |
DR status and VA |
Nature of stimulus |
Conclusions |
|
|
|
|
|
|
|
|
|
|
|
|
|
Presence/absence of |
|
|
|
|
|
|
macular edema was |
|
|
|
|
|
|
correlated to decreased |
|
|
|
|
|
|
CS, but there was no |
|
|
|
|
|
|
significative difference |
|
|
|
|
|
|
between the two groups |
Farahvash et al. |
Prospective |
17 Diabetic |
– |
26 Eyes-diffuse macu- |
Metrovision with |
CS had a significative |
[78] |
noncom- |
pts (34 |
|
lar edema |
a high resolu- |
improved after photoco- |
|
parative |
eyes) |
|
8 Eyes-focal macular |
tion cathodic |
agulation treatment only |
|
study |
|
|
edema |
ray tube stimu- |
in the frequency of 6.4 |
|
|
|
|
VA pre-treatment: 0.21 |
lator |
cpd |
|
|
|
|
VA post-treatment: 0.24 |
|
|
|
|
|
|
|
|
|
Pts patients; VA visual acuity; CS contrast sensitivity; DR diabetic retinopathy; bDR background diabetic retinopathy; PDR proliferative diabetic retinopathy; CSME clinically significant diabetic macular edema; IDDM insulin-dependent diabetes mellitus; NIDDM non insulin-dependent diabetes mellitus; cpd cycles per degree