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NR 4-6/2007
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Macular
microcirculation blood flow changes after conventional surgery
for rhegmatogenous retinal detachment
Zmiany w mikrokrążeniu
plamki po konwencjonalnej operacji odwarstwienia siatkówki
Agnieszka Kubicka-Trząska, Alina
Górniak-Bednarz
Department of Ophthalmology, Clinic of Ophthalmology and Ocular
Oncology,
Medical College, Jagiellonian University, Kraków, Poland
Head: Ass. Prof. Bożena Romanowska-Dixon, MD, PhD |
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| Summary: |
Purpose: To assess the
macular microcirculation blood flow in patients after
conventional surgery for rhegmatogenous retinal
detachment (RRD)with Doppler laser scanning (HRF –
Heidelberg retinal flowmeter).
Material and methods: Thirty patients (13 males and 17
females) in age: 28 – 68 years, mean age: 58.7 years
with unilateral RRD without macular involvement were
included in a prospective study. According to the type
of buckling procedure the patients were divided into 3
groups: I – encircling band (8 cases), II – encircling
band with radial or circumferential buckling (12 cases),
III – radial or circumferential buckling (10 cases). In
all patients the macular blood flow was measured with
Heidelberg retina flowmeter (HRF) before and 4 weeks
after scleral buckling procedures. Control group
consists of the fellow eyes.
Results: At the baseline examination in a group of eyes
with RRD the mean values of macular blood flow were
significantly lower comparing to fellow eyes and reached
respectively: 298.4 ± 79.2 AU and 435.6 ± 121.0 AU
(p=0.001) and correlated with the extent of RRD
(p<0.05).
Four weeks after surgery eyes that underwent the
buckling procedures showed the elevation of macular
blood flow as compared to the baseline values (p=0.001),
however they remain slightly lower as compared to fellow
eyes. The macular microcirculation blood flow changes
were not influenced by the type of scleral buckling
(p=0.2).
Conclusions: In the eyes with rhegmatogenous retinal
detachment without macular involvement the mean macular
microcirculation blood flows were lower as compared to
fellow eyes. Different buckling procedures for
rhegmatogenous retinal detachment influence the macular
blood flow, causing its improvement as compared to the
preoperative status but they remain lower comparing to
fellow eyes. |
| Słowa kluczowe: |
Odwarstwienie siatkówki,
procedura opasania twardówki, badanie Dopplerowskie,
mikrokrążenie plamkowe. |
| Key words: |
Rhegmatogenous retinal
detachment, scleral buckling procedures, Doppler laser
scanning, macular microcirculation blood flow. |
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Conventional retinal surgery
involves the creation of inward indentation of the sclera.
Scleral buckling procedures are the methods of treatment for the
most of uncomplicated rhegmatogenous retinal detachments (RRD).
In some cases however in spite of a good anatomic success, even
in patients without macular involvement, the deterioration of
macular function after scleral buckling procedures has been
noted. There are some evidences that the pathogenesis of these
abnormalities is associated with the disturbances of retinal and
choroidal circulation after RRD conventional surgery (1-5).
There are many methods of measurement of the ocular blood flow:
colour Doppler ultrasonography, Doppler velocimetry, the laser
speckle method, pulsatile ocular blood flow technique and
videofluorescence angiography (1-6). However, the evaluation of
the macular microcirculation by these techniques is difficult.
Heidelberg retina flowmeter (HRF), which combines the technique
of laser Doppler flowmetry with laser scanning technology, can
measure the blood flow within the macular region.
There are many publication about the haemodynamic parameters
changes in the ophthalmic artery, short posterior ciliary
arteries, long posterior ciliary arteries, central artery of the
retina and choroid in patients before and after scleral buckling
procedures for RRD (1-5,7-11). But we found only two studies
about the evaluation of retinal microcirculation blood flow
using Doppler laser scanning in patients with RRD who underwent
the conventional retinal surgery (12,13).
The aim of this study was to assess the behavior of macular
microcirculation blood flow in patients before and after
conventional surgery for RRD without macular involvement using
Heidelberg retina flowmeter.
Material and methods
Thirty patients with unilateral RRD without macular
involvement, who underwent uncomplicated scleral buckling
procedures, were included in a prospective study. There were 13
males and 17 females, aged from 28 – 68 years, mean age: 51.7
yrs ± 15.3. The entry criteria for the study were RRD localized
to the periphery of the fundus, not involving the macula and
clear optic media. Patients presenting eye diseases: glaucoma,
diabetic retinopathy, retinal vasculitis and uveitis and
systemic disorders such as systemic hypertension and diabetes
were excluded. The duration of RRD was from 4 days to one month;
the mean time of duration of the symptoms was: 19.6 days.
The diagnosis of RRD was established based on a standard
ophthalmic examination which included: best corrected visual
acuity, intraocular pressure measurement, anterior segment
examination and indirect ophthalmoscopy using a +90 D lens.
The best corrected visual acuity in the affected eyes ranged
from 1.0 to 0.6 and in the fellow eyes: 1.0 to 0.5. Refraction
of the affected eyes ranged from 0.0 D to -10.0 D and in the
fellow eyes from 0.0 D to -8.0 D. The intraocular pressure in
the affected eyes was: 10.7 ± 2.8 mmHg and in the fellow eyes:
13.2 ± 1.8 mmHg. Six patients had pseudophakia and two aphakia
in the affected eye. The extent of RRD ranged from 3 clock hours
to 8 clock hours (mean: 4.5 clock hours). In all cases the
retinal breaks were identified; there was a single retinal break
in 18 eyes and in 12 eyes, the number of retinal breaks ranged
from 2 to 4. In 14 eyes with high myopia the peripheral
vitreo-retinal degenerations (lattice and snail-track
degenerations) were present. In both pre- and postoperative
examinations no pathology within the macula was detected in 26
eyes, while 4 of them demonstrated the presence of discrete
pigment mottling.
According to the type of buckling procedure the patients were
divided into 3 groups: I – encircling band (8 cases), II –
encircling band with radial or circumferential buckling (12
cases), III – radial or circumferential buckling (10 cases). In
all cases surgery was performed under local anaesthesia. Scleral
buckling procedures included transscleral cryotherapy of the
retinal breaks and co-existing retinal degenerations, then in
local buckling a silicone sponge No. 504, No. 506, No. 507
(MIRA, Inc., USA) was used. In encircling procedure, a silicone
band No. 240 (MIRA Inc., USA) was used. The extent of the
explants was consistent with the size and location of retinal
breaks and co-existing peripheral degenerations. Subretinal
fluid was drained externally in 17 patients. There were no
intraoperative complications. At the end of the surgery indirect
ophthalmoscopy revealed retinal reattachment.
The tissue blood flow in the macular area was measured using a
scanning laser flowmeter (Heidelberg retina flowmeter,
Heidelberg, Germany). The measurement area included a zone of 10
x 2.5°, that equals to 2.8 x 0.7 mm. During each measurement the
foveola was located in the central part of the scanned area
Measurements were performed at least three times for the macular
area. The macular blood flow was measured before surgery and 4
weeks postoperatively.
The results of microcirculation blood flow were presented in
arbitrary units – AU. The calculation of macular capillary blood
flow was performed with AFFPIA program (automatic full-field
perfusion image analyzer). The differences in macular blood flow
between affected and contralateral eyes were statistically
analyzed using a unpaired t-Student test for independent trials.
Correlations between macular blood flow and clinical factors
such as age, duration and extent of RRD were determined by
multiple regression analysis. In order to evaluate the influence
of surgical factors: type of buckling procedure and drainage of
subretinal fluid, unpaired t-Student test was used. A
probability value of less than 0.05 was considered to be
statistically significant for all statistical analysis.
Control group consists of the fellow eyes, which showed no
pathology within the macular region.
Results
At the baseline examination in a group of eyes with RRD the
mean values of macular blood flow were significantly lower
comparing to the fellow eyes and reached respectively: 298.4 ±
79.2 AU and 435.6 ± 121.0 AU (p=0.001).
We noted that the preoperative macular blood flow had a
significant correlation with the extent of RRD (p<0.05); the
more extent area of RRD the lower macular blood flow was
detected. No significant correlation was found according to the
duration of RRD, refraction, number of retinal breaks and
patient’s age.
Four weeks after surgery eyes that underwent the buckling
procedures showed elevation of macular blood flow comparing to
the preoperative values (p=0.001), however they remain lower as
compared to the fellow eyes, but the difference did not reach a
statistically significant level (p=0.1).
After surgery the visual acuity was maintained at baseline
levels in 18 cases, improved in 8 (by 1-3 lines on Snellen
charts), and deteriorated in 4 patients (by 1 to 2 lines). In
eyes with postoperative visual acuity changes we did not find a
correlation between the level of visual acuity and the values of
macular blood flow.
There was no statistically significant difference between the
rates of macular blood flow in three groups of patients
classified according to the type of buckling procedure, however
the postoperative values of macular blood flows were lower in
cases underwent encircling procedures alone or with additional
local buckling
The drainage of subretinal fluid had no influence on macular
microcirculation blood flow 4 weeks after surgery.
Discussion
Based on literature it has been known that RRD without macular
involvement and various scleral buckling procedures influence
the ocular blood flow. Reduction of the blood flow in the
central retinal artery, main branches of the central retinal
artery, the ophthalmic artery, choroid after conventional
surgery for retinal detachment has been presented in many
publications (1-5,7,9,10). However there is scant information
about the evaluation of the macular microcirculation blood flow
in patients with RRD. It has been known that in some cases, in
spite of good anatomical results of RRD surgery, the vision
might be affected. It is postulated that this complication may
be associated with haemodynamic changes in ocular circulation
followed by RRD conventional surgery. Compression on the
peripheral vasculature by indentation caused by the scleral
buckle or encircling element might be responsible for the
alterations in ocular blood supply (5,7,10,14).
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Ohkubo using fluorescein
angiography presented signs of reduced retinal perfusion in
regions of reattached retina that was indented by scleral
buckling (14).
Studies in which the laser Doppler method was used showed that
pulsatile retinal arterial blood flows in eyes that underwent
RRD surgery were altered, and on average 50% were lower as
compared to the fellow eyes (15).
Using bidirectional laser Doppler, Ogasawara et al. reported
that in patients after the RRD surgery the blood flow rates in
the major temporal retinal arteries were on average 50% lower in
treated eyes than in the contralateral eyes (9).
Regillo et al. using colour Doppler imaging indicated that
scleral buckling with encircling elements decreased average
blood flow velocity in the central retinal artery by 35% and
50%, one day and one week postoperatively, respectively (7).
Nagahara et al. analyzed the effects of scleral buckling and
encircling procedures on retinochoroidal circulation within the
macula using the laser speckle method (1). The investigators
reported that foveal blood flow was normal before and after
surgery, however decreased blood velocity in the choroid and
retina on buckled area were noted. The data obtained from the
foveal region using the laser speckle method was assumed to be
affected only by choroidal circulation because the area was free
from retinal capillaries and the measuring depth was about 1mm.
The measuring depth by the HRF is 300 μm and the measured area
is 2.8 x 0.7 mm thus the contribution of the foveola in this
method is extremely small (12).
In our group of patients using HRF technique we noticed
reduction in the macular blood flow before surgery in the
affected eyes. The same observations were published by other
investigators. Eshita et al. in a group of 28 patients with
unilateral RRD demonstrated that the mean blood flow in macular
area before surgery was lower as compared to the fellow eyes
(12). The same results were demonstrated by Sanabary; in 20
cases with unilateral RRD the retinal blood flow was
significantly lower in detached eyes than in healthy,
contralateral eyes (13).
Four weeks after surgery in our group of patients we observed
improvement in the macular blood flow as compared to baseline
rates, however it remained slightly lower as compared to the
fellow eyes. This observation suggests that scleral buckling
procedures improve abnormal microcirculation in the macular area
in the patients with RRD. This finding is consistent with a
report by Eshita et al.; the authors demonstrated the
normalization of the preoperative reduction of the macular blood
flow one month after surgery (12). In another paper, the
analysis of the macular blood flow and perfusion with HRF before
and two weeks after surgery, revealed that different buckling
procedures can reduce retinal blood flow by about 13-20% (13).
The discrepancy between the postoperative retinal blood flow in
our study and the results presented in a study by Sanabary might
be associated with different time of follow-up periods.
We found the significant correlation between the degree of
disturbances of the retinal microcirculation in the macular area
and the extent of RRD, whereas no correlation was detected with
age, number of retinal breaks and duration of RRD. The same
results were presented by Eshita et al.; the authors showed that
the preoperative a/f ratio (affected to fellow eye macular blood
flow ratio) had a significant correlation only with extent of
RRD (12). As presented in our study and also in literature the
type of buckling procedure may influence the postoperative rates
of macular blood flows. The rates of macular microcirculation
blood flows were lower in patients who underwent encircling
procedures. This observation might be associated with 360o of
extent of scleral encircling band and the more extensive area of
compression on the peripheral vasculature as compared to local
bucklings which results in more alterations in ocular blood
supply in these cases. The results of our study showed that the
drainage of subretinal fluid did not influence the values of
macular microcirculation after surgery. The same observations
were published by others (12).
Conclusion
Based on results of our study in eyes with RRD without macular
involvement the mean macular blood flows before surgery were
lower as compared to the fellow eyes. Different buckling
procedures for RRD change the macular blood flow, causing its
improvement as compared to the preoperative status, but they
remain lower comparing to the contralateral eyes.
References:
1. Nagahara M., Tamaki Y., Araie M., Eguchi S.: Effects of
scleral buckling and encircling procedures on human optic nerve
head and retinochoroidal circulation. Br J Ophthalmol 2000, 84,
31-36.
2. Yokota H., Mori F., Nagaoka T., Sugawara R., Yoshida A.:
Pulsatile ocular blond flow: changes associated with scleral
buckling procedures. Jpn J Ophthalmol 2005, 49(2), 162-165.
3. Ito Y., Sasoh M., Ido M., Osawa S., Wakitani Y., Uji Y.:
Effects of scleral buckling without encircling procedures on
retrobulbar hemodynamics as measured by color Doppler imaging.
Arch Ophthalmol 2005, 123(7), 950-953.
4. Raczyńska K., Grabowska A., Zdybel E., Studniarek M.,
Dembicka H., Klawiter-Rydz M.: Przepływ naczyniowy u chorych z
odwarstwieniem siatkówki w kolorowej ultrasonografii
dopplerowskiej. Klin Oczna 2003, 105(1-2), 24-26.
5. Hanioglu-Kargi S., Yazar Z., Ziraman I., Guesel E.: Effects
of scleral buckling on the retrobulbar haemodynamic changes. Eye
2000, 14, 165-171.
6. Satoh Y.: Retinal circulation in rhegmatogenous retinal
detachment demonstrated by videofluorescence angiography and
image analysis. Acta Soc Ophthalmol Jpn 1989, 93, 1002-1008.
7. Regillo C.D., Sergott R.C., Brown G.C.: Successful scleral
buckling procedures decrease central retinal artery blood flow
velocity. Ophthalmology 1993, 100(7), 1044-1049.
8. Jukic T., Katusic D., Cikara I., Kordic R., Sikic J.,
Vukojevic N., Saric B.: Ocular blood flow parameters in patients
with rhegmatogenous retinal detachment. Coll. Antropol. 2005,
29(1), 75-79.
9. Ogasawara H., Feke G.T., Yoshida A., Milbocker M.T., Weiter
J.J., McMeel J.W.: Retinal blood flow alterations associated
with scleral buckling and encircling procedures. Br J Ophthalmol
1992, 76, 275-279.
10. Santos L., Capeans C., Gonzales F., Lorenzo J., Codesito J.,
Salorio M.S.: Ocular blood flow velocity reduction after
buckling surgery. Graefes Arch Clin Exp Ophthalmol 1994, 232,
666-669.
11. Vetrugno M., Gigante G., Cardia L.: The choroidal
circulation after retinal detachment surgery. Clin Hemorheol
Microcirc 1999, 21, 349-352.
12. Eshita T., Shinoda K., Kimura L., Kitamura S., Ishida S.,
Inoue M., Mashina Y., Katsura H., Oguchi Y.: Retinal blood flow
in the macular area before and after scleral buckling procedures
for rhegmatogenous retinal detachment without macular
involvement. Jpn J Ophthalmol 2004, 48, 358-363.
13. Sanabary Z.E.: Study of retinal blood flow after different
buckling procedures. Bull Egyptian Ophthalmol Soc 2000, 93(4),
387- 391.
14. Ohkubo H.: Fluorescein angiographic findings in the detached
and reattached retina. Jpn J Ophthalmol 1988, 32, 423-428.
15. Yoshida A., Hirokawa H., Ishiko S., Ogasawara H.: Ocular
circulatory changes following scleral buckling procedures. Br J
Ophthalmol 1992, 76, 529-531.
XXVIII Sympozjon Retinologiczny, PTO, Poznań
12-14.04.2007 r.
Praca wpłynęła do Redakcji 19.02.2007 r. (929)
Zakwalifikowano do druk 25.03.2007 r.Adres do
korespondencji (Reprint requests to):
Agnieszka Kubicka-Trząska MD
Lea Street 244/7
30-133 Kraków
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