Available via license: CC BY-NC-ND 4.0
Content may be subject to copyright.
ACTA CHIRURGICA LATVIENSIS • 2015 (15/1)
46
SUMMARY:
Introduction.Retrospective study were made to find out the correlation between visual field functional and optic nerve disc structural
damage of patients with glaucoma in early and late stage of disease.
Aim of the study. The aim of the present research was to characterize the relationships between visual field functional and optic
nerve disc structural damage of patients with glaucoma in different stage of disease and create the basis of correlation.
Material and methods. Together 94 patients (137 eyes) were analyzed from Pauls Stradins clinical university hospital ophthalmology
clinic, whom during years 2010 – 2012 were made computerized visual field at least more than 3 times and optical coherence
tomography (OCT) research in one day. Following data as retinal nerve fiber layer scan with OCT of optic nerve disc and visual
field were analyzed. Patients were divided into two groups according to the vision field functional damage severity. First group -
patients in moderate stage of glaucoma, but second – in late stage of disease. From visual field examination was rated numerical
corrected/pattern deviation map from age related norm values and compared with OCT Spectralis optic nerve retinal nerve fiber layer
measurements using Garway – Heath map.
Results. The average age of patients were 73.94 years ± 6.95 years. Glaucoma in moderate stage was diagnosed in 96 (70.1%) of
patients eyes, but in late stage – 41 (29.9%) eyes. In moderate stage the positive correlation was found in 72.9%% (70/96), but in
27.1% the correlation was not found with one of the diagnostic methods. (p<0.01). Looking trough out the results in moderate stage
of disease the structural damage was recognized in 91.66% (88/96) cases, but functional visual field loss in 81.25% (78/96) cases.
In severe stage of glaucoma the positive correlation between the diagnostic methods was in 92.68% (38/41), but in 7.32% (3/41)
the OCT didn’t show the damage as wide as visual field. (p<0.18).
Conclusion. Correlation between functional changes diagnosed by OCT RNFL scan and structural damage shown by computerized
perimetry data seems to depend on the stage of glaucoma.
Key words: glaucoma, visual field functional damage, optic nerve disc structural damage, optical coherence tomography retinal
nerve fiber layer scan, computerized perimetry
ORIGINAL ARTICLE
Correlation Between Visual Field Functional
and Optic Nerve Disc Structural Damage
of Patients With Glaucoma
Eriks Elksnis*,** Ilze Lace*
*Riga Stradins University, Riga, Latvia
**Department of Ophthalmology, Pauls Stradins Clinical University hospital, Riga, Latvia
AIM OF THE STUDY
The aim of the present research was to characterize the
relationships between visual field functional and optic
nerve disc structural damage of patients with glaucoma
in different stage of disease and create the basis of
correlation.
MATERIAL AND METHODS
In this retrospective study, wich was conducted in Pauls
Stradins Clinicac University Hospital, Ophthalomogy
clinic, together 94 patients with before diagnosed
glaucoma were analyzed, whom during years 2010
– 2012 were made computerized visual field and
OCT spectralis optic disc retinal nerve fiber layer scan
researches in the same day. Patients were divided
into two groups according to visual field damage
criteria from American Academy of Ophthalmology
ICD-9 glaucoma staging. First group of patients,
who had moderate-stage of glaucoma (optic nerve
disc abnormalities consistent with glaucoma and
glaucomatous visual field abnormalities in one hemi
field, second group consisted of patients with severe-
stage of glaucoma, advanced-stage glaucoma, end-stage
glaucoma (optic nerve abnormalities consistent with
INTRODUCTION
Functional loss in glaucoma is usually insidious and
starts peripherally, leaving patients asymptomatic in the
early stages of the disease. Currently, we do not have
any clinically applicable direct way to measure neuronal
loss in glaucoma and we use, instead, different surrogate
measures to estimate the functional and structural loss
in this disease. It is a paramount importance to have
sensitive and specific tests to detect subtle optic nerve
and/or visual field changes both for early diagnosis of
the disease and for monitoring it. Optic disc and visual
field assessments are a complex task, that have become
an integral part of glaucoma management. Until
recently, most studies have relied on subjective and
nonquantitative ways to assess structural damage. With
the advantage of automated imaging techniques, we
have, for the first time, the capability to reliably quantify
structural loss in glaucoma. (10) It is fair to say that these
new structural tests as optical coherence tomography
(OCT) and functional tests as automated perimetry are
allowing us to reexamine the nature and the strength of
structure – function correlation in glaucoma.
10.1515/chilat-2016-0009
Unauthenticated
Download Date | 5/16/16 3:02 PM
ACTA CHIRURGICA LATVIENSIS • 2015 (15/1)
47
glaucoma and glaucomatous visual field abnormalities
in both hemi fields. (9)
To assess functional damage, the numerical corrected/
pattern deviation map according to age related norm
values from the glaucoma hemifield test of computerized
visual field were rated, which is highly believed the
single most useful statistical analysis for glaucoma
diagnostics and monitoring. (1) To differentiate the
glaucomatous visual field damage from normal visual
field, only deviation of -5dB or greater from age related-
normal sensitivity, wich is quite unusual-and therefore
statistically significant, was accepted for further analysis.
(3) To measure the damage of optic disc the optical
coherence tomography (OCT spectralis) retinal nerve
fiber layer (RNFL) scan and analyses were overlooked.
(Table 1. Table 2.)
To evaluate the structure-function relationship the
Garway-Heath dot map was used as an example of
topographic map for correlating areas of visual field to
the optic disc. (11)
In Pauls Stradins Clinical University Hospital,
ophthalmology clinic for glaucoma diagnostics generally
30-2 point system of glaucoma hemifield visual field is
used, which measure visual sensitivity at 76 locations,
but Garway-Heath map is designed for 24-2 visual field
point test, which consists of 54 test points, which are
the most central test locations and subset of those in the
30-2 test pattern. Essentially a 24-2 test is just a 30-2
with all of the outer ring of test points removed, except
for the nasal-most two. (2)
All the comparison of data named before consisted of
3 steps:
1. Modification of the visual field 30-2 pattern test
analyses to 24-2 pattern test.
2. Finding out statistically significant (-5 dB or more)
visual field damage points.
3. Converting the appropriate visual field areas to
OCT retinal nerve fiber layer scan test according to
Garway-Heath dott map.
Data were analyzed using SPSS statistical program
version 21.0 and Microsoft Office Excel 2007. The
obtained results were compared using χ square method
correlation test. The p value < 0.05 was accepted as
statistically valid.
RESULTS
As mentioned before 94 glaucoma patients (137 eyes)
with different stage according to damage of the visual
field were included in the study. The average age of
patients was 73.94 years ± 6.95 years. 62.5% females,
37.5% males. Glaucoma in moderate stage was
diagnosed in 96 (70.1%) of patients eyes, but in late/
severe stage – 41 (29.9%) eyes. In moderate stage of
glaucoma the positive and statistically proved correlation
between functional and structural damage was found
in 72.9%% (70/96) of cases, but in 27.1% (26/96) the
damage was not found with one of diagnostic methods.
(Table 3.) (p<0.01 χ square method). Looking trough out
the results in moderate stage of disease the structural
damage was recognized by OCT in 91.66% (88/96)
eyes, but functional visual field loss in 81.25% (78/96)
eyes. (Table 4.) In late stage of glaucoma patients the
positive correlation between the diagnostic methods
was found in 92.68% (38/41) eyes, but in 7.32% (3/41)
the OCT didn’t show the damage as wide as visual field.
(Table 5.) Unfortunately the correlation between those
two diagnostic tests in the late stage of the disease was
not statistically proved. (p<0.18 by χ square method).
DISCUSSION
There is no discussion that structure and function are
correlated in glaucoma and both are important for
making diagnosis of the disease and/or for monitoring
it. Studies that examined in grater details the structure-
function relationship in glaucoma patients have
produced variable results. (5; 7) The strength of the
relationship seems to depend strongly on the stage of
the disease, as well as on the techniques used to measure
the structure and function. (8) It is frequently believed
that optic disc changes and, particularly, RNFL changes
often occur before detectable visual field loss. According
to our results optic disc examination is more useful at
earlier stages in glaucoma.
As the disease progresses, and in end-stage glaucoma,
visual field examinations become increasingly important
in monitoring glaucoma, since often in advanced
glaucoma the tests measuring structure do not have
any dynamic range left to allow for meaningful clinical
decisions. (6) In individuals with well-established
glaucoma, there is often disconnection between
structural and functional progression, due in part of
limitations in our ability determine progression with
current clinical measures.
There are a number of limitations in the assessment
of the relationship between structure and function
in glaucoma: (1) problems related to variability of
functional and structural measures; (2) the fact that
stimulus size in automated perimetry is typically
uniform across the visual field, leading to a mismatch
between stimulus size and the respective field size,
which increases with eccentricity; (3) the debate as to
whether there is selective loss of certain subpopulations
of retinal ganglion cells in glaucoma; (4) problems with
background luminance in automated perimetry; and (5)
peripheral optical defocus due to peripheral refractive
errors. (4)
It is only fairly to say that there is no irreplaceable
diagnostic method for glaucoma diagnostics and
monitoring. The computerized visual field, OCT optic
nerve disc retinal nerve fiber layer scan compliments
each other.
CONCLUSION
Correlation between functional changes diagnosed
by OCT RNFL scan and structural damage shown by
computerized perimetry data seems to depend on the
stage of glaucoma. Optic disc examination with OCT
retinal nerve fiber layer scan is more useful at earlier
stages in glaucoma, but in advanced disease the visual
field become more important for monitoring glaucoma.
Unauthenticated
Download Date | 5/16/16 3:02 PM
ACTA CHIRURGICA LATVIENSIS • 2015 (15/1)
48
Table 1. OCT RNFL scan of moderate stage glaucoma.
From Ophthalmology department of Pauls Stradins clinical university hospital.
Table 2. OCT RNFL scan for severe stage glaucoma.
From Ophthalmology department of Pauls Stradins clinical university hospital.
TS
57
(129)
NS
71
(102)
N
74
(72)
RNFL Thickness [ųm]
300
240
180
120
60
0
0 45
TMP SUP NAS
position [0]
INF TMP
90 135 180 225 270 315 360
NI
66
(103)
TI
56
(134)
T
61
(69)
G
65
(94)
NS
29
(102)
TS
35
(128)
T
45
(69)
RNFL Thickness [ųm]
300
240
180
120
60
0
0 45
TMP SUP NAS
position [0]
INF TMP
90 135 180 225 270 315 360
TI
67
(134)
NI
47
(103)
N
33
(72)
G
42
(94)
Unauthenticated
Download Date | 5/16/16 3:02 PM
ACTA CHIRURGICA LATVIENSIS • 2015 (15/1)
49
Conflict of interest: None
REFERENCES
1. Anders Heijl, Vincent Michael Patella, Boel
Bengtsson. The field analyzer primer 4th edition,
Effective perimetry 2012, Chapter 1: The essentials
of perimetry: 6.
2. Anders Heijl, Vincent Michael Patella, Boel
Bengtsson. The field analyzer primer 4th edition,
Effective perimetry 2012, Chapter 4: Choosing a
test: 29.
3. Anders Heijl, Vincent Michael Patella, Boel
Bengtsson. The field analyzer primer 4th edition,
Effective perimetry 2012, Chapter 5: STATPAC
Analysis of Single Fields: 47.
4. Anderson RS. The psychophysics of glaucoma:
improving the structure/function relationship. Prog
Retin Eye Res 2006; 25(1): 79-97.
5. Artes PH, Chauhan BC. Longitudinal changes in the
visual field and optic disc in glaucoma. Prog Retin
Eye Res 2005; 24(3):333-354.
6. Blumenthal EZ, et al. Correlating structure with
function in end-stage glaucoma. Ophthalmic Surg
Lasers Imaging 2006; 37(3):218-223.
7. Garway-Heath DF, et al. Relationship between
electrophysiological, psychophysical, and
anatomical measurements in glaucoma. Invest
Ophthalmol Vis Sci 2002; 43(7):2213-2220.
8. Girkin CA. Relationship between structure of
optic nerve/nerve fiber layer and functional
measurements in glaucoma. Curr Opin Ophthalmol
2004; 15(2):96-101.
9. Ronald L Fellman, MD, OCS, Cynthia G Mattox,
MD, Kim M Ross, OCS, CPS, Academy Coding
Specialist, Sue ViccHrilli, COT, OCS, Academy
Coding Executive. Eye Net Magazine/October
2011/Know the Glaucoma Staging Codes.
10. Tarek M Shaarawy, Mark B Sherwood, Roger A
Hitchings, Jonathan G Crowston. Glaucoma vol.
one, Medical diagnosis & therapy 2009, Section 3,
Chapter 20, Structure and Function Relationships
in Glaucoma: 251.
11. Tarek M Shaarawy, Mark B Sherwood, Roger A
Hitchings, Jonathan G Crowston. Glaucoma vol.
one, Medical diagnosis & therapy 2009, Section 3,
Chapter 20, Structure and Function Relationships
in Glaucoma: 253-254.
Address:
Eriks Elksnis
Department of Ophthalmology,
Pauls Stradins clinical university hospital
Pilsonu 13, Riga, Latvia LV 1003
e-mail: eriks.elksnis@inbox.lv
Table 3. Sternght of function-structure in
moderate stage of glaucoma
Table 4. Moderate stage of glaucoma
Table 5. Strenght of function-structure in severe
stage of glaucoma
Unauthenticated
Download Date | 5/16/16 3:02 PM
