WHEN THE RK CUTS CROSSED THE LIMBUS

COVER FOCUS
WHEN THE RK CUTS
CROSSED THE LIMBUS
A MICS IOL with an aberration-free design addressed this patient’s particular needs.
BY ROBERTO BELLUCCI, MD; AND ANGELA PANICO, MD
Getting to Know the Patient
A 61-year-old man presented with decreased vision, especially for distance. He had undergone RK many years ago to
correct an unknown degree of myopia. He had been highly
satisfied with the results of the RK, and, for many years, he
had been spectacle independent. Now, however, he needed
positive spectacle lenses with increasing frequency.
The patient’s distance BCVA with refraction of
2.00 D sphere was 0.34 logMAR in his right eye, and
his distance BCVA with refraction of 2.50 D sphere
was 0.32 logMAR in his left. He was also presbyopic,
with 2.00 D add needed for near vision in each eye.
Slit-lamp examination after pupil dilation revealed
12-incision bilateral RKs with no transverse cuts. The
cuts unfortunately crossed the limbus, leaving little
room for cataract surgery incisions. The lenses showed
bilateral cortical cataracts. Fundus examination, IOP,
and ocular motility were unremarkable in both eyes.
Corneal tomography (Figure 1) showed a small central
area of significant flattening, with the lowest keratometry
(K) readings of about 32.00 to 33.00 D. Astigmatism was
1.83 X 160° OD and 2.56 X 19° OS. The area of corneal
flattening was inferiorly decentered in the patient’s right
eye, with a huge degree of coma aberration that was not
perceived by the patient. Pupil diameter was 2.16 mm OD
and 1.88 mm OS, a possible explanation for the relatively
good visual acuity the patient achieved with spherical
spectacle lenses despite the impaired corneal shape.
A
B
Figure 1. Corneal tomography in the patient’s right (A) and left (B)
eyes showed a small central area of significant flattening.
In our experience, the central
part of the cornea after RK
is flatter than is measured
either by automated refraction or by corneal topography.1,2 Therefore, we find it
necessary to remeasure the
post-RK patient’s visual acuity, looking for the maximum positive lenses. In the specific
case described in Getting to Know the Patient, the results in
the patient’s right and left eyes were 4.00 and 4.25 D sphere,
66 CATARACT & REFRACTIVE SURGERY TODAY EUROPE | JUNE 2016
respectively. With these lenses, the patient’s distance BCVA
was the same as with his (lower) distance correction, and his
near BCVA was the same as with his near vision correction.
With our examinations completed, we identified three
preoperative concerns in this case:
• No. 1: Existing RK with incisions crossing the corneal limbus;
• No. 2: Multifocal corneas in both eyes; and
• No. 3: High astigmatism and coma in the right eye,
apparently not disturbing the patient’s vision.
Given these concerns, what surgical approach would be
best, and which IOL?
Eye
Length (mm)
K readings (D)
Calculated and Chosen IOL Powers (D)
IOLMaster
IOLMaster
SRK-T
ASCRS
Implanted
OD
25.59
36.02 – 37.71
22.00
24.38
25.50
OS
25.63
30.65 – 36.53
25.50
28.55
30.00
Abbreviations: K = keratometry; ASCRS = American Society of Cataract and Refractive Surgery online IOL power calculator for eyes
after refractive surgery
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TABLE 1. CALCULATED AND CHOSEN IOL POWERS
Figure 3. The corneal incision is placed between two of the
RK cuts.
Figure 2. The Incise IOL, an aberration-free spherical lens.
PREOPERATIVE PLANNING: THREE DECISIONS
When planning surgery in this case, we had to make three
key decisions.
Decision No. 1: Not to employ laser-assisted cataract
surgery (LACS). Although successful LACS after RK has
been described in the literature,3-5 the fear of creating
capsulotomy bridges prompted us to prefer microincision
cataract surgery (MICS), a procedure that requires an incision of only 1.8 mm.6
Decision No. 2: Choice of IOL. We decided to use a spherical IOL because the patient had always used spherical spectacle
lenses with reported good distance BCVA before the cataract
developed. We selected the Incise MICS IOL (Bausch + Lomb;
Figure 2) for several reasons:
• The need to implant the IOL through a sub–2-mm
incision, even considering the high dioptric power probably required;
Figure 4. IOL implantation between two RK cuts was
accomplished without opening the incisions.
JUNE 2016 | CATARACT & REFRACTIVE SURGERY TODAY EUROPE 67
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CASE RECAP
WHO
61-year-old man with decreased vision,
especially for distance, who had undergone 12-incision bilateral RKs in which
the cuts crossed the limbus; he now
presented with cortical cataracts, a
small central area of significant corneal
flattening, astigmatism, and a large
degree of coma aberration that was not
perceived by him
WHAT
Decide how to (1) plan surgery given
that the existing RK incisions crossed
the corneal limbus, leaving not much
room for cataract surgery incisions,
and (2) select an IOL to provide the
patient with the best vision despite his
compromised corneas
HOW
A MICS technique requiring
an incision of only 1.8 mm and
implantation of a spherical IOL that is
compatible with MICS
• The aberration-free design of this IOL, which makes it
perfect for use in eyes with compromised corneas;
• The subjective irrelevance of the corneal astigmatism,
which allowed us to select a spherical IOL;
• The high Abbe number of this IOL, with good color
vision results to be expected;
• The low rate of posterior capsular opacification we have
experienced with this IOL; and
• The ease of explantation should either eye require IOL
exchange.
The Incise IOL is made of a hydrophilic acrylic material
with 22% hydration; it is rigid and has a good square posterior edge. This lens is popular in Italy in conjunction with
MICS, as it can be implanted through a 1.6-mm incision with
a wound-assisted technique or through a 1.8-mm incision
with in-wound implantation through a 1.5-mm injector.7
Decision No. 3: IOL power calculation. We used the
calculation sheets provided by the IOLMaster (Carl Zeiss
Meditec) and by the American Society of Cataract and
Refractive Surgery (ASCRS) online IOL calculator for eyes
after refractive surgery (Table 1). After considering the
patient’s multifocal cornea, the central corneal flattening
within the circumference measured by the IOLMaster, and
the preoperative refraction, we selected powers of 25.50 and
30.00 D for the patient’s right and left eyes, respectively, with
68 CATARACT & REFRACTIVE SURGERY TODAY EUROPE | JUNE 2016
the purpose of providing some pseudoaccommodation. If
the IOL power proved to be too high, we would have the
ability to exchange the IOLs if the patient could not tolerate the mild myopia; if it proved to be precisely right, the
patient could be spectacle-free for a number of years.
SURGERY
Surgery in the patient’s left eye took place in August
2015 and was uneventful. We were able to place the 2-mm
incision between two radial cuts without opening them
(Figure 3) and to implant the lens without problems
(Figure 4). After surgery, we immediately noted good distance and near UCVA (0.12 and 0.14 logMAR, respectively),
even though the autorefractor now indicated a refraction of
-2.00 -3.00 X 170°.
Surgery in the second eye was performed using the
planned IOL power, again with good postoperative distance
and near UCVA (0.08 logMAR and 0.01 logMAR, with -1.75 D
myopia measured by automated refraction, respectively).
The patient is now spectacle independent. His multifocal cornea provides the amount of pseudoaccommodation
required for near vision: a further indication that corneal
topography still must be backed up by clinical assessment,
despite the precision of the machines now available.
LESSONS LEARNED
Careful planning, considering not only the objective
technical data but also the patient’s history and subjective
preferences, was an important basis for the success of surgery in this case. So too was the availability of an IOL with an
aberration-free profile that is suitable for MICS implantation.
We recommend use of the Incise IOL for any patient after
RK or other forms of corneal refractive surgery. n
1. BellucciR, PalamaraA. Automatedrefractionineyeswithradialkeratotomy[inItalian]. Boll Oculist (Rome). 1994;73(Suppl3):63-67.
2. SeitzB, Langenbucher A. Intraocular lenspower calculationineyesafter corneal refractivesurgery. J Refract Surg.
2000;16(3):349-361.
3. WhitmanJ. Victusfemtolaser capsulotomyinpost RKcataract surgery. ‬ https://www.youtube.com/
watch?v=muoFf0dvD2c. AccessedMay11, 2016. ‬
4. JonesJ. Catalysfemtosecondlasercataractsurgery. https://www.youtube.com/watch?v=qX4kLGq1HS4. AccessedMay11, 2016.
5. WongS. LenSxlasercataractsurgerytechnique5-14-12. https://www.youtube.com/watch?v=jptn-bx8qQk. AccessedMay11, 2016.
6. AlióJL, ElkadyB, OrtizD. Corneal optical qualityfollowingsub1.8mmmicro-incisioncataract surgeryvs. 2.2mmminiincisioncoaxial phacoemulsification. Middle East Afr J Ophthalmol. 2010;17(1):94-99.
7. vonSonnleithner C, BergholzR, GonnermannJ, KlamannMK, TorunN, BertelmannE. Clinical resultsandhigher-order
aberrationsafter 1.4-mmbiaxial cataract surgeryandimplantationof anewasphericintraocular lens. Ophthalmic Res.
2015;53(1):8-14.
Roberto Bellucci, MD
Chief Ophthalmic Surgeon, Unità Locale Socio Sanitaria No. 20,
Verona, Italy
n [email protected]
n Financial disclosure: Consultant (Bausch + Lomb)
n
Angela Panico, MD
Ophthalmic Surgeon, Unità Locale Socio Sanitaria No. 20,
Verona, Italy
n [email protected]
n Financial interest: None acknowledged
n