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The Effect of Texturing the Intraocular Lens Edge on Postoperative Glare Symptoms
A Randomized, Prospective, Double-Masked Study
Will R. Meacock, FRCOphth;
David J. Spalton, FRCS, FRCOphth;
Saarg Khan, MB, BS
Arch Ophthalmol. 2002;120:1294-1298.
ABSTRACT
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Objective To determine whether texturing the optic edge of the intraocular lens
reduces photic symptoms in patients with square-edged acrylic intraocular
lense implants.
Methods Sixty patients underwent routine phacoemulsification performed by a
single surgeon and were prospectively randomized to receive either the standard
AcrySof MA30 intraocular lens (Alcon Laboratories, Ft Worth, Tex) (group 1)
or an MA30 intraocular lens with a textured optic edge (group 2). Patients
were seen at 1 month by an independent observer who was masked to treatment
groups. A questionnaire on photic symptoms was completed, and attempts were
made to elicit symptoms under mesopic and photopic conditions.
Results At 1 month postoperatively, 20 (67%) of 30 patients in group 1 noticed
symptoms compared with 4 (13%) of 30 patients in group 2 (P<.001). The mean duration of symptoms was 3.5 weeks in group 1
and 1 week in group 2 (P = .01). By provocative testing
under photopic conditions, symptoms could be elicited in 26 patients (87%)
in group 1 and 6 (20%) in group 2. No patients in either group were symptomatic
at 3 months postoperatively. Under mesopic conditions, symptoms could be elicited
in 27 patients (90%) in group 1 and 11 (37%) in group 2. There was no relationship
between the incidence of symptoms and the degree of intraocular lens–rhexis
contact.
Conclusion Photic phenomena can be significantly reduced by texturing the edge
of a square-edged profile AcrySof intraocular lens.
INTRODUCTION
POSTOPERATIVE GLARE phenomena after surgical treatment for cataract
were first reported by Masket et al.1 They
found that 45% of patients with ovoid (5.0 mm x 6.0 mm) 1-piece all–polymethyl
methacrylate (PMMA) intraocular lenses (IOLs) described photic glare symptoms
compared with 22% of patients with round (5.5 mm) PMMA IOLs. The optics of
these 2 IOLs were studied using scatterometry, which measures the amount of
light reflected off materials, and ray tracing analysis, which determines
the fate of bundles of light rays passing through the IOL. Results showed
that the thickened edge of the ovoid optic was associated with increased light
scattering.
Posterior capsule opacification has been shown to be significantly reduced
by IOLs with a square-edged profile,2-4 but
in some patients, this has been associated with postoperative glare phenomena.
Symptoms have been reported with square-edged acrylic (AcrySof; Alcon Laboratories,
Ft Worth, Tex) and silicone IOLs.5-6 Symptoms
are most commonly noticed in the first few weeks after surgical treatment,
usually in conditions of mesopic illumination when there is a peripheral light
source from overhead or the temporal side. Using ray-tracing techniques, Holladay
et al7 have shown that these symptoms are due
to internal light scattering from the IOL edge onto the retina. In most patients,
these symptoms resolve over a period of a few weeks, probably due to fibrosis
of the rhexis edge around the IOL. In some patients, symptoms persist, possibly
due to a larger pupillary diameter in younger patients, a more posteriorly
positioned IOL with a greater space between the IOL and the iris in myopic
eyes, or from failure of the rhexis edge to adequately opacify with AcrySof
IOLs.8 On occasion, symptoms have been intractable,
and it has been necessary to explant the IOL.9 After
it is replaced by a rounded-edged IOL, symptoms have resolved, providing circumstantial
evidence that a square-edged optic is the cause of the symptoms.
Recently, a variation of the AcrySof IOL has been developed in which
the optic has a textured edge. On examination, this has a frosted appearance.
The aim of this prospective, randomized study was to determine whether texturing
the square edge of an AcrySof IOL reduces postoperative photic glare phenomena.
METHODS
Following approval from the hospital ethics committee and informed consent,
patients were recruited from October 1999 through March 2000. All patients
were seen preoperatively by the same clinician (W.R.M.). Inclusion criteria
were the presence of senile cataract in an otherwise normal eye in patients
older than 60 years. Exclusion criteria were a history of any previous ocular
disease, intraocular surgery, laser treatment, diabetes requiring medical
control, glaucoma, previous uveitis, or posterior segment abnormalities that
would preclude a postoperative visual acuity of 20/40 or better.
All patients underwent phacoemulsification with continuous curvilinear
capsulorrhexis, performed by a single surgeon (D.J.S.) using peribulbar anesthesia.
The surgical technique and medication were standardized. A temporal clear
corneal section was made, and the anterior chamber was re-formed with Healon
(Pharmacia, Uppsala, Sweden). A continuous curvilinear capsulorrhexis of approximately
5 mm was performed so that the anterior capsule flap lay on the implant optic.
The nucleus was removed by a phaco-chop technique, and soft lens material
was removed by irrigation-aspiration with balanced salt solution (Alcon Laboratories)
containing vancomycin hydrochloride (concentration, 20 mg/L) and epinephrine
bitartrate (1:100 000; 1 mL/L). No attempt was made to remove lens epithelial
cells by polishing the anterior capsule. The bag was re-formed with Healon
and the section enlarged to 3.5 mm. Preoperatively, patients were randomized
to receive either a 5.5-mm, 3-piece AcrySof IOL manufactured via the old process
(MA30BM) (group 1) or a 5.5-mm, 3-piece AcrySof IOL manufactured with the
new process, resulting in a textured optic edge (designated for this study
as MA30BT) (group 2) (Figure 1).
The material and geometry of both IOLs were otherwise identical. The IOLs
were inserted in the bag, and Healon was removed by irrigation aspiration
with balanced salt solution. If there were any surgical complications, such
as capsulorrhexis rim tear, zonular dehiscence, posterior capsule rupture,
or vitreous loss, the patient was excluded from the study and replaced. Postoperatively,
all patients used Maxitrol drops (neomycin sulfate, polymyxin B sulfate, and
dexamethasone 0.1%; Alcon Laboratories) 4 times a day for 1 month. No nonsteroidal
anti-inflammatory preparation was used preoperatively, perioperatively, or
postoperatively. Postoperatively, all IOLs were confirmed to have in-the-bag
placement.
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Figure 1. Scanning electron photomicrographs
of an intraocular lens with a textured edge (A) and a lens of the same design
but with a smooth edge (B).
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At 1 month postoperatively, all patients were assessed by an ophthalmologist
(W.R.M. or S.K.) who was masked to which group the patients had been assigned.
Pelli-Robson contrast sensitivity and ETDRS (Early Treatment of Diabetic Retinopathy
Study) visual acuity were measured. All patients completed a questionnaire
to determine the following: (1) presence of symptoms, (2) their postoperative
duration, (3) the time of day they were most noticeable, (4) the relationship
to the direction of light that induced them, (5) their impact on daily activities,
and (6) the pattern of glare experienced, with reference to a sheet illustrating
the various forms of glare phenomena (Figure
2). Patients were then examined under both photopic and mesopic
conditions to provoke the symptoms. With the patient looking in the primary
position at all times, a penlight was moved in an arc toward the peripheral
visual field. The visual field was divided into 8 segments, and patients were
asked to describe the presence and type of glare with reference to the pattern
sheet. If symptoms were elicited in any sector, the test was regarded as positive.
Following pupillary dilatation, slitlamp biomicroscopy was performed to determine
the degree of IOL-rhexis contact and the presence of vertical striae through
the center of the posterior capsule. Pupil diameter was not measured in the
study. Patients with symptoms still present at 1 month postoperatively were
reassessed at 3 months postoperatively using the same protocol.
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Figure 2. Patterns of photic glare.
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The Fisher exact test was used to analyze the proportion of patients
with symptoms, the impact of symptoms on the patients, and the type of photic
phenomena under mesopic and photopic conditions. An unpaired t test was used to compare the duration of symptoms and the means of
visual acuity and contrast sensitivity data.
RESULTS
Of 60 patients, 30 were allocated to each group. All patients in group
1 (untextured IOL) were available for postoperative assessment at 1 month
and 3 months, when necessary. In group 2, (textured-edged IOL) 1 patient failed
to attend the 1-month assessment because of illness. The mean age was 76 years
in group 1 (range, 65-83 years) and 74 years in group 2 (range, 60-86 years).
There was no difference between the 2 groups in age and sex distribution.
At 1 month postoperatively, the mean ETDRS visual acuity was 0.02 for
group 1 and 0.00 for group 2 (P = .70). Mean Pelli-Robson
contrast sensitivity was 1.48 and 1.51 for groups 1 and 2, respectively (P = .30).
At 1 month postoperatively, 20 patients (67%) in group 1 experienced
photic glare symptoms compared with 4 (13%) in group 2 (P<.001; relative risk, 5.00; 95% confidence interval, 1.9-12.9).
The mean duration of symptoms was 3.5 weeks for patients in group 1 and 1
week in group 2 (P = .01). No patients in either
group had symptoms at 3 months postoperatively. The symptomatic patients in
both groups noticed the photic phenomena more commonly from peripherally directed
light, particularly from overhead light. In group 1, patients tended to experience
symptoms more commonly at night (Figure 3). In group 1, the symptoms had no impact in 6 (30%) of 20 patients,
13 patients (65%) were aware of them, and in 1 patient (5%) they were a nuisance.
In group 2, symptoms had no impact in 3 (75%) of 4 patients, and 1 patient
(25%) was aware of them (Figure 4).
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Figure 3. The time of day when photic phenomena
were noticed by symptomatic patients with textured-edged or smooth-edged intraocular
lenses (IOLs).
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Figure 4. The impact of symptoms on patients
with photic phenomena. IOL indicates intraocular lens.
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With provocative testing under photopic conditions it was possible to
elicit symptoms in 26 patients (87%) in group 1 and 6 patients (20%) in group
2 (P<.001)
(Figure 5A).
Under mesopic conditions, photic phenomena were elicited in
27 patients (90%) in group 1 and in 11 patients (37%) in group 2
(Figure 5B). Flare
(Figure 2, patterns 7-11) was the most commonly elicited glare pattern
in group 1 under both light conditions. In group 2, there was no pattern bias.
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Figure 5. Patterns of elicited photic glare
phenomena under photopic (A) and mesopic (B) conditions. IOL indicates intraocular
lens.
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The relationship between the number of quadrants of IOL–rhexis
contact and the presence of symptoms is given in Table 1. At 1 month postoperatively, the incidence of symptoms did
not increase in those patients with more optic edge exposure (P = .25). There was no relationship between the presence of vertical
striae in the posterior capsule and the incidence of photic symptoms.
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Photic Glare Symptoms and IOL–Rhexis Contact in Patients With
Smooth-Edged or Textured-Edged IOLs
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COMMENT
The excellent visual outcome from modern phacoemulsification can be
impaired by the unwanted images produced by photic glare phenomena, and because
of the increasingly high expectations of patients, the phenomena need to be
eliminated. Several features related to the design of IOLs have been associated
with photic glare phenomena. Apple et al10 reported
a case of a pilot who had monocular glare symptoms at night after the implantation
of a 6-mm round PMMA lens with 4 positioning holes around the optic edge.
Symptoms were abolished by an IOL exchange. In a separate report, Landry11 indicated that IOL positioning holes were responsible
for the unwanted photic images, and such observations have led to their subsequent
removal from the majority of implants in the manufacturing process. In the
late 1980s and early 1990s, IOLs with 5.0 mm x 6.0 mm ovoid optics,
constructed from round PMMA IOLs with the opposing sides truncated, were popular,
but if the implant was positioned horizontally, patients experienced glare
symptoms from superiorly located light sources, such as room lights and the
sun. The reports of glare phenomena with ovoid IOLs has since made them unpopular.12-13
Mamalis and Spencer14 recently reported
the results of a physician survey concerning the explantation of foldable
IOLs. This survey reported that visual aberrations or optical phenomena were
reported by 24% of patients with 3-piece monofocal silicone lenses, 27% of
patients with 1-piece plate haptic silicone lenses, and 28% of patients with
3-piece acrylic lenses. A square edge is, therefore, not the only requirement
for an IOL lens to produce photic phenomena. Tester et al15 conducted
a telephone questionnaire to investigate the incidence of unwanted light images
with different IOLs. They surveyed patients with 6 IOL types: AcrySof 5.5-mm
(MA30) and 6.0-mm (MA60) IOLs, the Allergan SI-40 (Allergan, Inc, Irvine,
Calif), the Staar/Chiron plate haptic lens (Staar Surgical Co, Monrovia, Calif,
and Chiron Corporation, Emeryville, Calif), and 2 PMMA IOLs (5.5 mm and 6.0
mm) and compared them with 50 controls with presbyopia. Patients were contacted
between 6 and 12 months after surgical treatment for cataract to identify
whether they were experiencing glare phenomena. Those with symptoms were asked
to describe the pattern, the light conditions under which they occurred, and
the effect they had on vision. Interestingly, the rates of glare and sensitivity
symptoms in patients with AcrySof or SI-40 IOLs were similar to those of the
controls. However, patients with IOLs had more unwanted images than did controls.
Patients with AcrySof and SI-40 IOLs reported the highest incidence of unwanted
images (MA30, 30%; MA60, 35%; SI-40, 24%; compared with the control group,
4%). The SI-40 lenses have, in some cases, been successful in reducing photic
symptoms after IOL exchange of an AcrySof lens. The authors could not explain
the incidence of photic symptoms among patients with SI-40 IOLs in this survey.
Similar rates of symptoms in the AcrySof and PMMA 5.5-mm and 6.0-mm optic
IOL groups suggest that optic diameter is not particularly important in causing
symptoms. Overall, this paper shows that light-induced symptoms are common
in both patients with presbyopia and patients with pseudophakia. It is difficult
to identify their precise cause, and it is uncommon for them to be bothersome.
Our study investigated photic phenomena in 2 square-edged 5.5-mm 3-piece
AcrySof IOLs, one with a smooth optic edge and the second with a textured
edge. We have shown that patients who received the textured implant had a
statistically significant reduction in the incidence, duration, and severity
of edge glare symptoms. From Holladay's study using ray tracing in round-edged
and square-edged IOLs,7 the most likely explanation
for this result is that light reflected off the internal IOL edge surface
is more scattered by the textured-edged lens, and a focused internal image
is not created. It was important to take into account the effect of IOL-rhexis
contact on the incidence of symptoms in both groups of patients. The capsule
on the anterior surface of the IOL optic undergoes fibrotic changes (anterior
capsule opacification [ACO]) in the early postoperative period. This decreases
the transparency of the anterior capsule and will increase the dispersion
of light entering the eye, with the potential to reduce glare. In a histological
study, the rate of ACO was found to be dependent on the type of implant.8 Silicone plate haptic IOLs produced high ACO scores,
whereas 3-piece acrylic optic/PMMA haptic IOLs produced little ACO. Increased
ACO might be beneficial in preventing photic symptoms, although it could lead
to IOL decentration if the forces on the IOL are asymmetrical. The low rate
of ACO with acrylic IOLs has the potential therefore to make these IOLs more
susceptible to photic glare phenomena. In our study, Table 1 shows that there was no relationship between the number
of quadrants covered by the rhexis and the presence of symptoms. This is not
surprising because by 1 month postoperatively, when the patients were first
questioned, ACO would have had little time to develop.
No statistical differences in visual acuity or contrast sensitivity
were detected between the 2 lens groups. Despite the high incidence of elicited
symptoms with the smooth square-edged IOLs, only 1 patient reported any difficulties
in daily visual tasks due to the presence of photic images, and none of the
patients reported symptoms beyond 3 months postoperatively. This is not surprising
given the relatively small group of patients studied and the fact that photic
symptoms tend to be reported by younger patients with a high degree of critical
awareness. This study has shown, however, that texturing the optic edge surface
is very successful in reducing postoperative photic symptoms and has the potential
to improve the quality of vision for patients.
AUTHOR INFORMATION
Submitted for publication August 15, 2001; final revision received June
11, 2002; accepted June 14, 2002.
This study was presented at the annual meeting of the European Society
of Cataract and Refractive Surgery, Brussels, Belgium, September 6, 2000.
Corresponding author: David J. Spalton, FRCS, FRCOphth, Department
of Ophthalmology, St Thomas Hospital, Lambeth Palace Road, London SE1 7EH,
England.
From the Department of Ophthalmology, St Thomas Hospital, London, England.
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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES
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