Loupe Magnification for Small Incision Cataract Surgery - an Alternative to Microscope Magnification ?

ORIGINAL ARTICLE
J Nepal Med Assoc 2008;47(172):210-4
Loupe Magnification for Small Incision Cataract Surgery - an Alternative
to Microscope Magnification?
Singh SK,1 Winter I,2 Hennig A3
1Medical Director, Biratnagar Eye Hospital, Biratnagar, Nepal, 2Vitreoretinal Consultant, Biratnagar Eye Hospital, Biratnagar, 3Pro-
gramme Director, Sagarmatha Chaudhary Eye Hospital, Lahan, Nepal
AbStRACt
A Prospective randomized controlled study was conducted to compare outcome of Small Incision
Cataract Surgery (SICS) using microscope or loupe magnification.
Two hundred fifty one patient with mature cataract were randomly allocated to SICS-Fishhook
Technique with either microscope (127 eyes) or loupe (124 eyes) magnification. Intra- and
postoperative complications and immediate visual outcome were analyzed.
Nearly two third (microscope 65% and magnifying loupe 62.9%) of all patients had good visual
outcome on first postoperative day. Poor outcome (<6/60) was recorded in 8% (microscope group)
and 7% (magnifying loupe group). Mean visual acuity with Snellen was 0.39 (SD 0.2) in microscope
group and 0.38 (SD 0.2) in magnifying loupe group. Intra operative complications were comparable
in both groups. Mean surgery time with loupe magnification was significantly shorter.
Comparatively equivalent good surgical outcome was achieved with loupe as well as with microscope
magnification. However performing SICS with loupe magnification is significantly faster. Small
incision cataract surgery with loupe magnification is safe and effective procedure for cataract surgery
so it can play a role in reducing cataract blindness in developing countries of the world.
Key words: loupe, magnification, microscopic, cataract, surgery
INtRODUCtION
Cataract is the leading cause of blindness in the world
procedures with in-the-bag intraocular lens insertion.
causing more than 18 million bilateral blindness.
High volume SICS has become an accepted surgical
1-3 Most
of these blind people reside in developing countries.
technique with good visual outcome to deal with the
4
Ophthalmologists working in rural areas of a developing
cataract backlog in developing countries.5-7 Microscope
country face a Herculean task to deal with huge backlog
magnification is nowadays widely used for cataract
of cataract blindness.
surgery, whereas few centres use high quality prism
loupes to perform high volume SICS.6,8 This is the first
With the changes in cataract surgical techniques
study to determine whether loupe magnification is an
during the last decade’s surgeons require a higher
alternative to microscope magnification for performing
magnification to perform good quality extracapsular
SICS.
Correspondence:
Dr. Sanjay Kumar Singh
Biratnagar Eye Hospital, Biratnagar, Nepal.
Phone: +9777-21-533660
Email: sanjay.nepal@gmail.com
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Singh et al. Loupe Magnification for small Incision Cataract Surgery-an Alternative to microscope magnification?
MAtERIAL AND MEtHODS
was done and superior equator of the nucleus was
lifted from the capsular bag. Following the injection of
A prospective hospital based randomized study was
viscoelastics behind the lens nucleus into capsular bag
conducted at Biratnagar Eye Hospital (BEH), Nepal, for
the lens nucleus could then be delivered with fish hook
a period of one month (13 March 2007 to 12 April
technique. With a Simcoe cannula the remaining cortex
2007). Verbal consent was taken from the patients.
was aspirated. PMMA posterior chamber intraocular
lens was implanted and anterior chamber was filled with
Mature senile cataracts (white or brown) were included
ringer lactate solution. The operation was completed
for this study. All patients underwent slit lamp
with an intracameral injection of cefuroxime. The
examination. Immature cataract, complicated cataract,
surgical time was measured from the preparation of
congenital cataract, developmental cataract and
the sclerocorneal incision to the end of the intracameral
cataract associated with other diseases were excluded
cefuroxime injection.
from this study.
Study variables included surgeon’s time, intraoperative
Patients with mature senile cataracts were divided into
and postoperative complications and postoperative
two groups before receiving retrobulbar anaesthesia.
uncorrected visual acuity on first postoperative day.
Randomization was done with the help of random
Postoperative uncorrected visual acuity was taken with
number tables. Patients with odd numbers were selected
Snellen chart at a 6 meters distance and for the purpose
for microscope magnification and even numbers were
of calculation was converted into decimel figure.
selected for loupe magnification. All patients were
operated by a single surgeon (SKS).
RESULtS
As the operating surgeon was the only ophthalmologist
Two hundred fifty one patients consented for the study,
available at BEH at the time of this study, masking
127 were operated under microscope (Group A) and
did not seem practical. All cases were operated and
124 with magnifying loupe (Group B).
examined in the postoperative period by him. However,
the visual acuity recording person was not aware of the
Baseline characteristics were similar in both groups. In
study and masking could be achieved.
group A 83.5% (106 out of 127) had vision of hand
movement while the remaining patients had visual
A hand-held Auto Refract Keratometer (NIKON
acuity of 0.03. In group B 80% (99 out of 124) had
Retinomax K plus 2) was used for keratometry and A
vision of hand movement and remaining had visual
Scan ultrasound machine (Nidek ECHO scan US 800)
acuity of 0.03.
for the purpose of axial length measurement. The
power of the intra ocular Lens was calculated with the
Mean intraocular lens power was similar in both
modified SRK II formula.
groups. Patients from group A had 22.25 D (SD 1.24)
and from group B had 22.29 D (SD 1.29). Posterior
After pupil dilatation with Tropicamide and Phenylephrine
capsule rupture with vitreous loss occurred in four
eye drops a retrobulbar injection was given in sitting
patients from group A and one patient from group B.
position and the patient requested to press the eye ball
Inadvertent intracapsular cataract extraction occurred
with the palm of the right hand to soften the eyeball.
in one patient from group A. All patients with posterior
Preoperative povidone iodine 10% solution was used
capsule rupture and intracapsular cataract extraction
for disinfection of the periocular skin area.
underwent anterior vitrectomy and had intraocular lens
implantation. In group B, one patient had premature
The surgeon performed the operation in either sitting
entry and another had wound gap and one suture was
position on two tables with microscope or standing
applied in both these patients to secure the wound.
position on three tables with a magnifying loupe. Part of
the surgical steps such as fornix based conjunctival flap
Mean time spent by the surgeon per surgery was 4
and cauterization of bleeding vessels were performed
minute 29 seconds in group A and 3 minute 50 seconds
by an operation theatre assistant in order to help
in group B. In group A 28.3% patients and in group
optimizing the surgical time.
B 68.5% patients had surgery time of less than four
minutes (P value <0.00003).
Carl Zeiss microscope (OPMI -1 FR) or high quality Carl
Zeiss Prism loupe with 5 times magnification and 300
Postoperative complications were noticed among
mm working distance in combination with a halogen
nine patients in group A and six patients in group B.
Spot light were used for the purpose of magnification.
One patient each from both group had to undergo
Frown shaped scleral incision, sclerocorneal tunnel,
surgical revision on second postoperative day for
anterior chamber entry and linear capsulotomy were
PCIOL repositioning. Hyphaema (4 patients), increased
made with a 3 mm diamond keratome. Hydrodissection
anterior chamber reactions (2 patients), corneal edema
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Singh et al. Loupe Magnification for small Incision Cataract Surgery-an Alternative to microscope magnification?
(2 patients), air bubble in anterior chamber (1 patients),
Surgeries with magnifying loupe were performed
posterior capsule opacification (1 patient) and retinitis
in standing position whereas with microscope the
pigmentosa (1 patient) were responsible for poor visual
sitting position was more practical. It is easier for the
acuity on first postoperative day in the group A. In group
operating surgeon and the assistant likewise to move
B hyphaema (1 patient), corneal edema (4 patients)
from one table to another in standing position. Lesser
and age related macular degeneration (1 patient) were
magnification, flexibility in judging intraocular structures
responsible for poor visual outcome. All patients but
from different angles during surgery, and probably lower
retinitis pigmentosa (1 patient) and age related macular
number of posterior capsule rupture with vitreous loss
degeneration (1 patient) recovered with good outcome
resulted in a shorter mean surgical time with magnifying
at the time of discharge.
loupe (3 minute 50 seconds) compared to microscope
(4 minute 29 seconds). Change in head posture of
Postoperatively uncorrected visual acuity was measured
patient during surgery requires vertical and horizontal
on the first postoperative day at 7 a.m. immediately
adjustment of optical part of the microscope to remain
after removal of the eye pad. In both groups nearly two
in good focus of the operation site whereas with the
third (group A 65% and group B 62.9%) of patients
magnifying loupe the surgeon can adjust immediately
had good visual outcome (6/6-6/18) (P value 0.3669).
by just moving his head as required. These results in
Mean visual acuity was 0.39 (SD 0.2) in group A and
a shorter time needed for focus adjustment with loupe
0.38 (SD 0.2) in group B. Poor outcome (Unaided visual
magnification. Venkatesh et al from a high volume set
acuity <6/60) was noticed in 8% patients from group
up of SICS at Aravind Eye Hospital reported less than
A and 7% patients from group B.
4 minutes surgical time per case with microscope.7 In
DISCUSSION
this prospective study, twelve surgeries per hour could

be performed with microscope whereas up to eighteen
Preoperatively nearly all patients were blind in both
surgeries per hour could be performed with magnifying
groups (group A 97% blind and group B 98% blind).
loupe. Ruit et al reported 8-10 cases per hour with
On day one postoperatively, 92% of patients had
microscope using single long table.10
uncorrected visual acuity better than 6/60 in group A
A good quality operating microscope is expensive
and 93% in group B. Similarly both groups (microscope
equipment for many private eye clinics and eye units
65% vs. magnifying loupe 63%) had comparable good
in this part of the world. Compared to Zeiss operating
visual outcome better than 6/18 (P value 0.3669). Only
microscope, Zeiss magnifying loupe is much cheaper,
one patient from both groups had poor visual acuity at
easy to transport and almost maintenance free.
the time of discharge.
However an external high quality light source is needed
Hennig et al in their prospective study achieved good
to work with the Zeiss magnifying loupe. Cost of the
visual outcome in 76.8% operated cases with loupe
Zeiss magnifying loupe used for this surgery was Euro
magnification at the time of discharge.8 Another study
700 and the one halogen illumination (Hanalaux) used
of small incision cataract surgery with microscope
for this surgery has a price of Euro 1500. This adds up
showed that only 47.9% of eyes obtained uncorrected
to Euro 2200 for equipping a surgeon during SICS with
visual acuity of 6/18 or better at 6 weeks.9
magnifying loupe. However good quality light sources
manufactured in India may be bought cheaper and
Intraoperative complications were comparable in
will decrease the total cost involved for surgery with
both groups. There were five cases of intraoperative
magnifying loupe. In comparison OPMI-1 FR used for
complications in group A vs. three cases in group B. Four
this study was purchased for Euro 7200. Introduction
posterior capsule breaks with vitreous loss occurred in
of high quality Zeiss magnifying loupe in the operation
the group A whereas only one in the group B.
theatre of eye units for small incision cataract surgery
will increase the efficacy of ophthalmic surgeons
Surgical time included all surgical steps performed by
without compromising the surgical quality and without
the surgeon during the surgery. It did not include the
increasing the cost.
time taken by ophthalmic paramedics for the preparation
of operating eyes. With magnifying loupe, surgeries
Blind people living in hilly and mountainous areas have
were performed on three tables and with microscope
difficulties in accessing eye care services because of
surgeries were performed on two tables. While surgeon
difficult terrain.11 Surgical eye camps are therefore still
was carrying out surgery on one patient, ophthalmic
common and acceptable means of reducing the burden
paramedics cleaned the periocular area, draped the eye,
of cataract blindness in these communities.12 It is always
prepared the conjunctival flap and cauterized the bleeding
a difficult task to carry a portable microscope and
vessels of other patients. More patients from the group
generator along with other necessary instruments and
B (68.5%) had mean surgical time less than 4 minutes
disposables for cataract surgery to these areas. Surgery
compared to 28.3% in group A (P value<0.00003).
with high quality Zeiss magnifying loupe could be an
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Singh et al. Loupe Magnification for small Incision Cataract Surgery-an Alternative to microscope magnification?
excellent and reliable replacement for cataract surgery
In plains areas of Nepal all eye hospitals have increased
with operating microscope on cataract blind patients in
number of patients in the busy periods (October to
remote hilly areas and in other remote places.
March). Introduction of loupe magnification will help to
raise the number of cataract surgeries performed by
In past times a magnifying loupe was used to improve
these hospitals. Improved efficiency of cataract surgeons
the visibility and safety during intracapsular cataract
with higher surgical output from these hospitals may
extraction procedures. With the shift to extracapsular
help in adjusting the fee structure of cataract surgeries,
cataract extractions operating microscope was used
thus making it more affordable to the poorer people in
routinely for the purpose of magnification. In developing
need living in developing part of the world.
countries where largest numbers of cataract blind
patients live, ophthalmic surgeons are trained to operate
CONCLUSION
with microscope during their residency and fellowship
programs and instinctively believe that cataract
Small incision cataract surgeries were performed faster
surgeries done under microscopic magnification yield
with equally good visual outcome and comparative
a better outcome. Findings of this study clearly show
complication rate under high quality magnifying loupe
that for small incision cataract surgeries, high quality
magnification. In developing countries where cataract
magnifying loupe is as effective as the good operating
blindness is a major cause of avoidable blindness, small
microscope and at the same time surgeries can be
incision cataract surgery with high quality magnifying
performed faster. In a high volume surgical set up,
loupe could be an appropriate and more universal skill
introduction of high quality loupe magnification instead
for the reduction of cataract blindness. A high quality
of microscope magnification will increase the numbers
magnifying loupe is a good alternative to the operating
of cataract surgeries without increasing the number of
microscope and provides similar surgical outcome with
cataract surgeons.
increased output.
table 1. baseline characteristics
Microscope (Group A)
Magnifying loupe (Group b)
P value
Age (Mean +/- SD)
62.4 ( SD 11.9) yrs
62.7 ( SD 11.7) yrs
Male
48%
47%
0.4364
VA (HM or worse)
83.5%
80%
0.2389
Mean VA (remaining patients)
0.03 (SD 0.02)
0.03 (SD 0.05)
table 2. Intraoperative findings
Microscope (Group A)
Magnifying loupe (Group b)
Mean IOL power
22.25 D (SD 1.24)
22.29 D (SD 1.29)
Intraoperative complications
PCR + vitreous loss: 4
PCR + vitreous loss: 1
ICCE: 1
Premature entry: 1
Wound gap: 1
Mean surgery time >4 min
71.7%
31.5%
P value <0.00003
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